'A-600/9-75-003
SCIENTIFIC SEMINAR
ON
AUTOMOTIVE
POLLUTANTS
FEBRUARY 10-12, 1975
THOMAS JEFFERSON
MEMORIAL AUDITORIUM
WASHINGTON, D. C.
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DISCLAIMER
This report has been reviewed by the Office of Research and
Development. Mention of trade names or commercial products
does not constitute endorsement or recommendation for use.
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BpA-.600/9-r
******
12,
February 10"
Thomas
U.S. Environmental Protection Agency
Region 5 Ubrary (PL-12J)
77 West Jackson Blvd., 12th Floor
Chicago, IL 60604-3590
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INTRODUCTION
On February 10-12, 1975 the Scientific Seminar on Automotive Pollutants
was held in the Thomas Jefferson Memorial Auditorium at the U. S. Department
of Agriculture in Washington, D. C. The purpose of the Seminar was to continue
to assemble information on the health effects and atmospheric chemistry of
air pollutants, primarly NOx but also CO and HC, from automobiles, by
offering the scientific community and other interested persons this forum as
an opportunity to present the most recent research knowledge.
This is a compilation of the papers presented at that seminar.
PEOTSCTIOH
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TABLE OF CONTENTS
o
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CO
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Section 1 Executive Summary
Section 2 Seminar Participants
Section 3 Monday
a. Honorable Russell E. Train
Dr. Herbert L. Wiser
Dr. Wilson K. Talley
b. Dr. James Pitts
University of California
Riverside
c. Mr. John Redmond
National Academy o| Sciences
d. Dr. Carl Shy
University of North Carolina
e. Mr. Louis Lombardo
Public Interest Campaign
f. Dr. Billings Brown
g. Dr. Harold McFarland
Gulf Oil Corportation
h. Dr. Richard Ehrlich
Illinois Institute of
Technology Research, Inc.
i. Dr. Donald Gardner
Experimental Biology Lab
EPA
Dr. James F enters
Illinois Institute of
Technology Research , Inc.
Introduction
Air Pollutants &
Public Health: Old
Problems & New
Horizons for NOx Control
NAS Report to the Senate
Committee on Public
Works - NOx Health Effects
Health Rationale for the
Existing Nitrogen Oxide
Emission Standards
A Case for Auto Emission
Control
The Rediculousness
of Present NOx Standards
Health Effects of NO2
& NO2 in Combination
With Other Pollutants
Interaction Between
NO2 Exposure &
Respiratory Infection
Time/Dose Response
for NO2 Exposure in
an Infectivity Model
System
Immunologic Response
During Exposure
to NO2
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k. Dr. Jean French
Human Studies Lab.
EPA
1. Dr. Samuel Epstein
Case Western Reserve
University
m. Dr. Daniel Menzel
Duke University
Recent Epidemiologic
Studies with Respect
to Nitrogen Oxide
Nitros amines
Implications of the
Molecular Mechanisms of
NO2 Intoxications to
Public Health
Section 4
Tuesday
a. Dr. John Knelson
Human Studies Lab.
EPA
b. Dr. Richard Stewart
Medical College of
Wisconsin
c. Dr. Edward Radford
Johns Hopkins University
d. Dr. Steven Horvath
University of California
e. Dr. Daniel Menzel
Duke University
f. Dr. Russell P. Sherwin
University of Southern
California
g. Dr. A. P. Altshuller
EPA
h. Dr. Basil Dimitriades
EPA
i. Dr. James Mahoney
Environmental Research &
Technology, Inc.
Health Effects of
Oxidants and Carbon
Monoxide
Carboxyhemoglobin
Trends in Chicago
Blood Donors
Recent Studies of
CO in Relation to
Heart Disease
Influence of CO on
the Working Capacity
of Man
New Pathways of
Sulfate and Nitrate
Transport in the Lungs
NO2
Aerometric Data
Analysis
Chamber Studies
National Academy of
Sciences Viewpoint
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j. Dr. R.A. Rasmussen
Washington State University
k. Dr. Thomas Hecht
Systems Applications, Inc.
1. Dr. Bernard Weinstock
Ford Motor Campany
Recent Field Studies
Modeling Evidence
Recent Advances in
Smog Chemistry
Prediction of Future
Urban CO Concentrations
Section 5
Wednesday
a. Dr. John Kinosian
California Air Resources
Board
b. Dr. James Edinger
University of California
Berkeley
c. Dr. Bruce Bailey
Texaco, Inc.
d. Dr. John Heuss
General Motors Corp.
e. Dr. Thomas Graedel
Dr. Beat Kleiner
f. Dr. Chet Spicer
Batelle Columbus
Labs
Ambient Air Quality
Trends in the Los Angeles
Basin
Los Angeles
Reactive Pollutants
Program - LARPP
Oxidant - HC-NOx
Relationships from
Aerometic Data -
L.A. Studies
Smog Chamber
Simulation of Los
Angeles Atmosphere
Chemical Kenetic
& Data Analytic
Studies of the Photo-
chemistry of the
Troposphere
Non-Regulated
Photochemical
Pollutants from
NOx, Nitric Acid, and
Nitrates
g. Dr. William Lonneman
PAN Levels
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SECTION 1
EXECUTIVE SUMMARY
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h. Dr. R. A. Saunders Commentary
Naval Research Lab Concerning a Rainwater
Analysis
i. Dr. Alan Bandy Studies of the
Old Dominion University Importance of Biogenic
Hydrocarbon Emissions
to the Photochemical
Oxidant Formation in
Tidewater, Virginia
Section 6 Appendix
a. Cover Letters
b. Federal Register Notice of Seminar
c. GM Comments
d. Mr. Louis Lombardo
Public Interest Campaign
e. Comments/Coordinating Research Council
f. Correspondence from
American Public Health Association
g. Notice of Seminar
h. Paper: Clarence M. Ditlow III
i. Conclusions - Environmental Research & Technology, Inc.
j. Questions - Compton/Rasmus sen
k. Health Effects Critique
1. Summary of Seminar
m. Address List of Speakers
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON. D.C. 20460
February 21, 1975
OFFICE OF
RESEARCH AND DEVELOPMENT
SUBJECT: Executive Summary of the Scientific Seminar on Automotive
Pollutants, February 10, 11, and 12, 1975
FROM: Herbert L. Wiser
Deputy Assistant Administrator for Environmental Sciences
Office of Research and Development (RD-682)
TO: The Administrator
THRU: AX
The attached executive summary of the Scientific Seminar on
Automotive Pollutants, which you opened February 10, 1975, is
provided for your information. It contains conclusions relevant
to standard setting which v/ere stated or derived from presentations
and discussions at the seminar.
An assemblage of almost all scientific papers presented will
be provided in a few days. A set of transcripts has Keen presented
to one of your staff.
Attachment
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EXECUTIVE SUMMARY |
*
SCIENTIFIC SEMINAR ON AUTOMOTIVE POLLUTANTS i
\
February 10-12, 1975 j
Washington, D.C. i
INTRODUCTION
» !
Evidence presented at this seminar contains some recent scientific •;
t
thinking which may have a bearing on administrative decision-making. i
For the most part, the papers presented and discussed on the health
effects of automotive pollutants were related to nitrogen oxides and ;
carbon monoxide, with one paper on the effects of ozone. It does not,
however, represent an exhaustive review of all extant data on the NOx
(,
problem, nor the CO and oxidant problems. Opinions of scientists >
presenting papers related to health effects at this seminar are
summarized in the attached table.
The detailed involvement of NOx in the oxidant-and ^-forming
processes is extremely complex and has been at issue. The problem
arises from the facts that (a) NOx is precursor of several photochemically
formed pollutants, namely: Oxidant (03), N02> toxic nitrates, and
visibility-reducing nitrates, and (b) control of NOx does not have the
same effect -- quantitatively or even directionally -- upon the various
pollutants that arise from NOx. Furthermore, precursor emissions in a
city cause pollution problems not only within the city, but also, after
transport, to distant non-urban areas located downwind; in these non-
urban oxidant situations the NOx involvement is not necessarily the
same as in the urban oxidant case.
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The oxid.-.nt and N02 navo b°en studied extensively and ar?
now subject to control regulations. The nitrates are not regulated
in any way riow, but concern for their adverse effects and their
identified formation in polluted atmospheres is growing.
The scientific evidence and viewpoints presented at the seminar
pertained mostly to the role of iiOx in the urban_ oxidant and urban K
problems. However, discussions were also included on the roles of
the anthropogenic and natural emissions in the non-urban oxidant problem.
on other (than oxidant and NC^) problems caused by NOx, and on methods
for calculating emission control requirements for inert pollutants (CO).
While most of the evidence and viewpoints discussed were directly
addressed to the question of the role of NOx, several presentations
were on subjects of general interest but only peripherally relevant
to the theme of the seminar.
PRINCIPAL SCIENTIFIC CONCLUSIONS
A. Health Effects
1) NOx: Regarding the delay of relaxation of the NOx standard,
two fundamental considerations must be recognized. First, any
basis for a decision of this nature must take into account the
recent recognition that short-tern, peak exposures play an
important role in the appearance of adverse health effects, and
must consider both stationary and mobile sources. Data and/or
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comments to this effect v/ere offered by eight speakers, whose
names appear on the attached table. While it appears necessary
to continue existing control of long-term exposures, these
health considerations point to the need for a complementary
strategy to define and limit short-term exposures,
The second fundamental consideration which surfaced refers
to the fact that EPA is confronted with indications that N0£
transformation products, for which standards have not been set,
may be associated with adverse health effects. Among the speakers
who addressed this point were Drs. Pitts, French, and Epstein,
In the absence of fully definitive data to assess the health
impact of increasing these products by increasing NO? emissions,
and to further assess short-term exposure, Dr, Shy advised that
it would be prudent to maintain the mobile source NOx standards
within the range 0.4 to 2.0 grams per mile at least until more
precise data can be obtained. A selected value within this range
would, of course, depend in part on the existing and anticipated
degree of stationary source NOx control. Mr. Ditlow presented
a written statement that in EPA's recent analysis of the con-
sequences of relaxing the NOx standard to 3.1 g/mi, short-term
exposures were not considered and, therefore, the analysis may
have underestimated the seriousness of the U.S. urban NOx problem.
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SPEAKERS OPINIONS REGARDING STANDARDS-
NOx
W-ints More
S t r i ni.cn t
Str>nd~irds
Supports
Present
Standard
Short-tenn
Standard
Dor.' t Won i
An/
Stantlj.'ri
Pilts (University of California - Riverside)
Td {National Ac .".deny of Sciences)
!,,' (University of ,. .rih Carol in^J
Lor,baruo (Public Interest C.j.iipa 15:1 ) -
Broim (Private Citizen)
'Icr^.-larJ IG_H' Gil I jr;, JT. t ion)
-r 1 i cl> (Illinois ! n: L i tu ti- of 1 echr.ol Of)y , Inc.)
Gardner (Environmental ProtecLior. Ago:icy - rtT
Feit-irs (illt'r._i-J Institute of Ti i-lir.oloiiy Research, Inc. )
E;jst in (J.i'jC V.'SUi'M f',e-.erv.; Un i veT'. i t y)
M_'n:-el (Di-.l-e University)
Shen/in (University <"if t j I i f<-,rn i,i - L.A.)
CO
Knel.on (£nvi ronT.er.: ;i 1 Protection Agency - ^Tp)
Sti.--.jrt (.VJir.jl Coli.'iie 01 V/l'.coiis i n )
".o: ford (Joliij h'o,ji(i;i'j Univi'i'ji
Ho."/ulh (jn i vor-j i ty of f\il i I ori, ia )
Knc'li.on (Environmental Protection A<;t.nc/ - ",TP)
-These opinions were deduced by staff fro-r. :hc papers given or fro,-, ,i-v«ers g v.-n to questions from the floor.
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2) CO: Data presented on CO generally suggest that the current
standard is adequate. (Drs. Stewart, Knelson, Radford, and Horvath)
3) Oxia'ants: Although health information on oxidants v/as
.limited to a presentation by Dr. Knelson, it appeared th^t
increased exposure to this pollutant above that currently
allowable is undesirable.
Role of NQx in the Oxidant and N02 ^Problems
Drastic but uncoordinated control of HC and NOx emissions
will not necessarily achieve the oxidant standard. This, in turn,
means that in order to achieve the air quality standard for oxidant,
it would be almost imperative that control of HC and NOx be
coordinated so as to achieve an optimally low HC-to-NOx ratio.
One main conclusion drawn from the presentations and discussions
is that oxidant concentrations exceeding the standard can form
from some combinations of extremely low HC and NOx concentrations,
comparable to those encountered in non-urban areas currently.
Such a conclusion appears to be supported by the field data, smog
chamber data, and modeling data.
Based on this conclusion, a rational control strategy for
achievement of the air quality standards in urban areas has been
agreed almost by concensus* to be as follows: Degree of KOx
control required should be equal to but not exceed the degree
of control needed to achieve th? air quality standard for NC^.**
Degree of HC control then required should be that needed for
achievement of the oxidant standard.
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It is reasonably certain that such a strategy will succeed in solving
the urban problems of fi02 and oxidant. Hov;sver, the strategy does
have limitations that should be recognized. Such limitations are:
1. The strategy may not be the most effective one
for control of non-urban pollution problems.
2. The strategy may not be the most effective one for
control of NOx - derived pollutants other than 03
and N02.
Revisions of this strategy to remove these limitations must await
generation of new evidence on (a) sources of non-urban oxidant.
(b) adverse effects of NOx - derived pollutants other than 03 and
N02, and (c) the dependence of such pollutants on their precursors.
*The HAS, in disagreement with this strategy, favors more stringent
control of NOx. However, the NAS justification is in part based
on concern for the non-urban oxidant problem. Considering the
urban problem alone, the evidence is overwhelmingly in favor of
the strategy recommended here.
**Such KOx control requirements were calculated by EPA-OA',-,1? recently.
Results showed that a light duty vehicle NOx emission standard
of 3.1-g/mile, soupled witn use of "maxinrizer1 stationary source
control technology and the new-source perforrancc standards, will
achieve and maintain the u'-.QS for N02 everywhere in U.S. except
in Los Angeles and Chicago.
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SYNOPSIS Of PRESENTATIOiiS
A. Health Effects
During the over/lev/ presentation and discussion on NC'<, several
general but nevertheless important conclusions emerged. First, in
considering the health implications of nit
recognized that multiple chemical and physical interactions and
meteorological conditions combine to produ
•ogen dioxide, it must be
:e a complex of nitrogenous
compounds, in addition to other pollutants, for which standards have
not been established. These nitrogenous compounds, having adverse
health implications, may include peroxyacetyl nitrate, other nitrates,
nitrites, nitric and nitrous acids, in addition to MO and flO^, Dr.
Epstein suggested that nitrosamines, which have carcinogenic properties,
may also be linked to NOx transformation processes. In the Los
Angeles basin, it has been estimated that. 50 percent of the suspended
aerosols are of secondary origin, that is, they are the result of
atmospheric transformation processes. During transformation or
conversion processes, aerosol particles of submicron dimensions are
generated. Particles in this size range are most significant to
visibility degradation and to adverse health effects. Tracer studies
show that these pollutants nay drift from region to region as shewn
by Dr. Pitts.
It was noted that stationary as well as mobile sources contribute
to nitrc^n oxide loading in th? at:;;csphero. It was estimated that
in the Los Angeles basin, if the current i;0x control program for
mobile sources is carried out into 1930 or the early 80's, stationary
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8
sources then will contribute as much to fJOx loading as will mobile
emissions (Pitts). Coal combustion in stationary sources represents
a significant contribution to total NOx emissions.
Based on single, 10 to 45 minute exposures to 'J02 of humans
t
in the laboratory, it was calculated that an adverse response
as indicated by significantly increased airway resistance could
be expected with single, 1-hour maximum N02 exposures of 0.40
to 1.33 ppm, meaning that these individuals had increased difficulty
moving air through the lung passages. Susceptible populations
could be expected to respond to the lower end of the range, or
at approximately 0.40 to 0.50 ppm. Animal and human data suggest
that resistance to respiratory infections may be impaired and
lung damage may occur with repeated, short-term exposures to 0.15
to 0.50 ppm H02- Susceptible individuals would likely be affected
at approximately 0.15 to 0.30 ppm NO?. (Shy).
Based on protecting susceptible individuals and providing a
margin of safety of approximately 2, a maximum allowable one-time
one-hour N02 exposure can therefore be projected as in the range
0.20 to 0.34 ppm. An analogous projection may be made for maximum
allowable repeated, short-term exposures as 0.03 to 0.20 ppm.
It should be recognized that these estimates are solely for N02
and do not include the potential for adverse effects which may
be associated with N02 transformation products. (Shy)
. To achieve the above exposure limits for short-term N02
concentrations, an NOx emission standard in the range of 0.4 to
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9
2.0 grans per mile has been projected. Dr. Shy indicated that there
is no reason to believe that an NOx emission standard above 2.0
grams per mile would achieve the indicated range of exposure limits.
The exact emission standard required to insure that 1-hour ambient
concentrations do not exceed 0.20 to 0.34 ppm would be determined
in part by the extent to which stationary source NOx is controlled.
Mr. Ditlow pointed out that a recent EPA analysis of the impact
of relaxing the statutory mobile source NOx standard to 3.1 grams
per mile is based upon the current ambient air quality NOo standard.
Since the ambient standard is given only as an annual average,
considerations of potential short-term peak exposure were not included,
and therefore this assessment of the IIO? situation may have underestimated
the seriousness of the NOx problem in U.S. cities.--
While the absence of adequate measurement methods for NOx do
not fully permit the precise quantitative results which are needed
for epidemiological studies, these studies can and do provide at
least qualitative indications of human response to nitrogen oxides.
Such measurement difficulties do not exist in controlled laboratory
studies.
There was consistent evidence fro:?, both animal and epidemiologic
studies that exposure to NO;? can alter the body's defense mechanisms,
which can result in an increase in susceptibility to infectious
disease. There was evidence that these? alterations are of long
duration. It is possible that short-term intermittent exposure may
be as toxic as continuous exposure. (Sherwin, Gardner)
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10
Additional data presented indicate that adverse health effects
may result from exposure to NOx transformation products such as
suspended particulate nitrates and nitric acid. Epidemiologic
studies have shown a significant association, of increased exa-
cerbation of asthma with suspended nitrates, This was substantiated
in an jn yitro lung model showing that increased histamine, a known
'broncho-constrictor, is released with exposure to ammonium nitrate
or ammonium sulfate, components of suspended fine particulates.(Menzel}
Another health effect mentioned, which may result from exposure to
either N0£ alone or in combination with other atmospheric pollutants,
was that of chronic respiratory disease; i.e, chronic bronchitis
or emphysema. (French)
Mr. Lombardo requested that EPA consider the history of mobile
source pollution control action and that EPA not relax the current
mobile emission standards. Dr. Brown presented a case for abolishing
the NOx standards on the ground that NOx is not a proven health
offender and that therefore benefits from KOx control are not com-
mensurate with fuel penalties and other economic costs. The technical
basis for Dr. Brown's assertions is soine;vrrat unclear, however, Dr.
HcFarland reported changes in pulmonary function in r.onkeys with
long-term exposure to 6-8 ppm tify; but these data appeared to be
somewhat out of the mainstream of the other c*t2 presented.
The CO studies presented showed that exposures to CO manifest
then-selves in a variety of responses. In controlled, human studies
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11
of exposure to CO resulting in c^rbo.'.y-err.cnlobin levels of approxi-
mately 4.5 to 5.0:i, a marked reduction occurred in both the capability
' t
for physical work and in mental vigilance. Animal studies on the
effects of CO showed a decrement in cardiovascular performance as
measured by EKG changes. Population studies indicated that a
decrease in carboxyhemoglobin levels from 1970 to 1974 was compatible
with a decrease in ambient CO measurements in the community studies.
(Horvath, Knelson, Stewart)
The data presented on health effects from ozone was based
primarily on controlled exposure studies in humans. These studies
looked at certain physiological parameters before and after exposure
to 0.4 ppm of ozone for four hours. A highly statistically signi-
ficant decrement was observed in the Ability of hu:':;an white blood
cells to engulf known doses of bacteria. Significantly increased
chromatid breaks were observed, as were significant decreases in
pulmonary function. All of these functions returned to normal
levels 4 weeks after exposure. (ICnelson)
B. The Role of NOx in the Oxidant and NOp Problems
The main question of interest, regarding the role of NOx, is
. "how are oxidant and N02 related to the NOx (and HC) precursors, or
what effect would control of NOx (and of i.'C) have on ambient
oxidant and i.'Op"? Studies addressed to this question were numerous
and, '\Tsed on the investigative rppro':;:h used, can be categorized
into three types: Aerr.netric Data Analysis Studio, Smog Chamber
Studies, and Modeling SIndies.
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12
1} Aerorcetric Studies: EPA studies (Altshuller) of early and
recent aerometric data from the CAMP network resulted in "upper
limit" curves (for each CAX? city separately) relating oxidant to
t
the HC precursor. Such curves, obviously, do not define the role of
NOx, but can be and have been used to check the validity of oxidant-
precursor relationships obtained from s^r.og chamber and modeling
studies. Most significantly, the Altshuller analysis suggested that
oxidant concentrations exceeding the standard could be formed from
extremely low hydrocarbon levels, comparable to those encountered in
non-urban atmospheres currently.
Washington State University studies (Rasmussen) indicated
that in some non-urban areas, elevated oxidant concentrations could
be a result of combined effects fro:n natural HC and anthropogenic
NOx emissions. Dr. Rasmussen's interpretation of the evidence
available was also that although natural sources can cause significant
oxidant accumulations, when such accumulation exceeds 0.08 ppm-03
then anthropogenic emissions can be said to be the cause.
Studies of Los Angeles data by the California Air Resources
Board (Kinosian) revealed air quality trends suggesting oxidant
reduction (in DOLA) as a result of HC reduction and NOx increase.
Mr. Kinosian expressed the viewpoint ti^i; in parallel with HC
control, control of NOx in LA is needed rainly to achieve
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13 \
the air quality standard for N02> but also to reduce
concentrations of toxic and visibility-reducing nitraces (in LA),
and to alleviate possible oxidant problems caused by (transported)
NOx in distant dov.'nwind" areas.
* *
A Texaco statistical analysis of all aerometric data taken in
the CAMP and other cities was interpret:! by the investigator,
Mr. Bailey, to suggest that (a) control of HC and NOx emissions to
as low levels as possible is counterproductive to the oxidant
control, (b) control of NOx beyond the present, degree is not. needed
except, in the Los Angeles basin, and (c) achievement of the oxidant
standard of O.CS ppin-03 is not possible since it requires reduction
of ambient HC concentration to below the background level.
Based on the NAS report to U.S. Senate Committee of Public
Works (Sept. 1974), Dr. Mahoney's presentation, and-'Dr. Midy's
written testimony, the NAS viewpoint appears to be that although
an auto emission standard of 0.4 g "Ox/mile is too stringent for
meeting the air quality standard for N0^:. it nevertheless should
not be relaxed. The NAS conclusions are based mainly on the
suspicion that the increase in NOx emissions in recent years
caused elevated oxidant concentrations in areas dov/nvnnd from the
source areas. The NAS, nevertheless, recor—.snds that irr.plementation
of the 0.4-g NOx/mile standard be delayed by 1-2 years, pending
completion of ongoing studies.
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A Bell Telephone Co. study (Graedc*!, Kleiner) of New Jersey
.and Pennsylvania data shoved that air quality on Sundays is as
bad as or worse than on workdays, in spite of the lower emission
rates on Sundays. The investigators offered tentative explanations
r
and concluded that the EPA-recommended control to reduce the
•
6-9 a.m. concentrations of precursors rnay not insure oxidant
reduction.*
Battelle (Spicer) and EPA (Lonneman) studies of urban and
non-urban atmospheres identified and measured several ,NOx-derived
pollutants, other than 63 and N02- The data raised the issue of
adverse effects from and need for control of such pollutants.
Finally, Dr. Bandy {Old Dominion University) reported that
in some rural sites in Virginia, naturally emitted terpones may
comprise as much as 10* of the total nan-methane 11C during spring;
the terpene contribution drops to zero during the "Sjnog season.
Reports were also made on the status of the Los Angeles Reactive
Pollutant (LARP) study (Edinger) and on a Naval Research Laboratory
study (Sanders) of air pollutants found in rain v;at:?r. Dr. Saunders
interpreted his results to suggest thnt natural emissions may
contribute to air pollution problems in a major v;ay.
*The Bel] Telephone consents suggest misinterpretation of the EPA-
recommended control strategy. The EPA rccc:r..r.endation is based on
an empirical correlation between 6-9 a.r.u concentrations of precursors
and maximum oxidant concentrations prr.t.rring Is tor in the day.
Because of the empirical nature of this correlation, reduction of
the 6-9 a.iii. pi ocursor concentrat'lors should be rccc.'i.J.'ished through
uniform emission control, mainl;. initu] di'jnul -rrnssicri patterns cciistari
The difference in emission patterns between Sundays r.nd workdays
explains, partly a: least, the difference in air qi;alicy, but it dees
not invalidate the EPA recommendation.
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2) Smog Chamber Studies: EPA (Diinitru'des) and General Motors
(Heuss) reported smog chamber data depicting the dependence of
oxidant and.t;02 on hydrocarbons and fiOx. In spite of so'ie
differences in resi.1 cs between the two studies, there was agreement
t
that hOx ar.d liC roles in oxidant- and ^--fon^ation are such
that uncoordinated control of HC and NOx is an ineffective strategy
to air quality improvement. A r;orc effective control strategy is
to control NOx as much as --no mora than — necessary in order to
achieve the KAQS for ?;C>2> and to control HC as much as necessary in
order to achieve the NAQS for oxidant. Nevertheless, smog chamber
data should bs looked at with some reservations since real atmospheric
conditions cannot be and are not fully reproducible in smog chambers.
Ford Motor Co. (Weinstock) surgesLc-cl that smog chamber data
should be viewed with caution as they way reflect extraneous effects
from contaminated charnbar walls. Dr. V.'einstock als'o discussed
methods for calculating emission control requirements for inert
pollutants.
3) Modeling Studies: Systems Applications, Inc., (Hacht) suggested
an NOx role similar to that depicted i-.y the smog chab-er studies.
This is to be expected, however, since the validation of photochemical
models presently available have bsen l^sc-d on sr;;og chamber data. The
models also suoqest that elevated 0? concentrations can form from
"' "" ^
extremely low HC and NOx concentration...
A Bell TO!"phone Co. study (Graecel-Kleiner) resulted in a model
capable of r-?.king reasonable predictions of certain air quality
characteristics. No evidence, hov/ever, v/as presented regarding the
role of NOx in air quality.
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SECTION 2
SEMINAR PARTICIPANTS
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Seminar Participants
Dr. A. P. Altshuller
Dr. Bruce Baily
Dr. Alan Bandy
Dr. Basil Dimitriades
Dr. Clarence M. Ditlow III
Dr. James Edinger
Dr. Samuel Epstein
Dr. James Fenters
Dr. Jean French
Dr. Donald Gardner
Dr. Thomas Graedel
Dr. Thomas Hecht
Dr. Jon Heuss
Dr. Steven Horvath
Dr. John Kino si an
Dr. Beat Kliner
Dr. John Knelson
Mr. Louis Lombardo
Dr. William Lonneman
Dr. James Mahoney
Dr. Daniel Menzel
Dr. Harold McFarland
Dr. James Pitts
Dr. Edward Radford
Dr. R. A. Rasmussen
Mr. John Redmond
Dr. R. A. Saunders
Dr. Russell P. Sherwin
Dr. Carl Shy
Dr. Chet Spicer
Dr. Richard Stewart
The affiliations and addresses of the above speakers appear in Section 6m
of this document.
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SECTION 3
MONDAY
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A. HONORABLE RUSSELL E. TRAIN
DR. HERBERT L. WISER
DR. WILSON K. TALLEY
INTRODUCTION
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HONORABLE RUSSELL S. TRAIN
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OPENING STATEMENT OF THE HONORABLE RUSSELL E. TRAIN
ADMINISTRATOR, ENVIRONMENTAL PROTECTION AGENCY
AT THE
t
SCIENTIFIC SEMINAR ON AUTOMOTIVE POLLUTANTS
WASHINGTON, D. C. - FEBRUARY 10, 1975 .
l"'am delighted to have this opportunity to open officially this seminar,
Scientific Seminar on Automotive Pollutants. The seminar is a vital part of
the information-gathering process in which EPA is engaged at the present
time to assist it in arriving at sound and effective policies with respect
to the control of auto emissions.
As you know, as Administrator, I must soon act on the one-year suspension
-application cf the industry. Beyond this, we must, as a'society, address
the need for a longer-range strategy which takes into appropriate account,
air quality and the protection of public health, technology and both economic
and energy costs.
For the past three weeks, we have been conducting a formal hearing on
auto emission issues with primary emphasis on matters of technology.
Today, inthis scientific seminar, we shift the focus to air quality, par-
ticularly as it relates to human health effects and the atmospheric chemistry of
automotive emissions.
In this regard, we will be especially interested in nitrogen oxide, carbon
monoxide, and hydorcarbons bccai;se of information recently generated in
this area.
Likewise, it is my intention in the immediate future to reconvene our
formed hearing panel to receive further testimony on the sulfate issue.
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Let us be entirely clear that while there are ahostof other factors which
should be considered in the development of a comprehensive auto pollution
control policy, the key issue of central concern must be for the protection
of public health; and there is no valid question whatsoever but that automotive
pollutants can have a significant adverse impact on human health.
Let me just inject at this point, a matter which I was discussing with
one of the members of the audience just before coming up here; and that is
-.that I am. really very deeply concerned about the course of recent judicial
decisions in this whole area of health effects and I am speaking particularly
of the Reserve Mining Case, involving the asbestos from taconite tailings
in Lake Superior, and the Ethyl Company Case involving lead emissions and
. low-lead regulations.
It seems to me that the trend in those cases is to place an almost
impossible burden of proof on EPA in establishing an endangerment to health;
and it is almost as if we were expected to produce a body count, so to speak,
before we were able, to the satisfaction of the courts, to establish a danger
to health.
It is ray feeling that if those decisions remain unmodified, that the ability
of the agency to carry out its responsibilities for the protection of public
health in these and related areas, is very substantially impared.
I raise this because I would hope that som'e of the participants in the
course of this seminar, over the next several days, will address this issue of
the scientific, determination of health risk.
It is a tough issue; it is one that I can understand the difficulites of
addressing in the courts; but it is an exceedingly important one, particularly
when there are multiple sources of pollutants; andil is particularly difficult
to maintain the burden of proof when there arc multiple sources and the
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court requires that the impact on the specific individual must be causally
traced to a particular one among a multiple number of sources.
I take this opportunity to -welcome those who are taking part in this
symposium. We are grateful to you for your participation. We need your
help. We must have the best and most recent scientific data upon which to
base policy decisions.
We need objective scientific guidance, not only for immediate regulatory
decisions, but also to help us anticipate v/hat obstacles and problems may
arise from so-called new pollutants, or even from the synergistic effects
of new control technology and of existing factors already part of the environment.
Now my closing paragraph says I am particularly pleased now to turn
the program over to Dr. Wilson Talley. I think that I should turn at this
point to Dr. Herbert Wiser. He will introduce Dr. T alley, the new Assistant
-.Admifti3lralor..for Research find Development., -as soon as he co'/aes in.
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DR. HERBERT L. WISER
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DR. HERBERT L. WISER
DEPUTY ASSISTANT ADMINISTRATOR FOR'ENVIRONMENTAL SCIENCES
ENVIRONMENTAL PROTECTION AGENCY
FEBRUARY 10, 1975
Thank you, Mr. Train, for your keynote remarks with regard to this
symposium.
I would like to make some administrative announcements before the actual
scientific part of the seminar begins, We will attempt to follow the agenda
as closely as possible. Changes will be announced daily.
We are'very pleased to have alarge number of papers presented in this
symposium; and originally what was to be a two-day meeting, has turned
into at least a three-day meeting. Therefore, the time constraints will
be quite tight.
Questions and discussions from the audience after every paper, are
welcome, but will be limited to approximately ten minutes. Please give
your name and affiliation before commenting from the floor.
For convenience, we have two microphones situated about halfway up each
aisle, for those who want to participate in the discussion. Anyone not
appearing on the program, who would like to give an oral presentation,
please notify me and we will try to arrange it.
In most cases, time permitting, these additional presentations will be
made at the end of every session.
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For convenience, we are having the Ace-Federal Reporters take notes
of the papers presented. Complete copies of the proceedings of this seminar
v/ill be available from Ace-Federal Reporters. Order forms will be avail-
able shortly, either from the reporter at the front of the auditorium or
at the receptionist's desk outside the auditorium.
As you know, the speakers were notified of this meeting only a few weeks
ago and, therefore, there was insufficient time to prepare reprints.
.Let 23 e. emphasize that this is .a scientific seminar to consider the facts
concerning the health effects and atmospheric costs of auto emissions.
I hope the discussions from the floor will limit themselves to these scientific
facts.
Before I introduce the first speaker, 1 would like to give you a feeling
as to how the program has been put together. Today, and half of the day
tomorrow, we will be concerned with the health effects ox auto pollutants;
today, primarily with the nitrogen oxides; and tomorrow morning, primarily
v/ith carbon monoxide.
There may be one or two papers in each -session out of place, primarily
because the speaker on such short notice could not arrange his schedule
to come at the right time.
Tuesday afternoon and all day Wednesday v/ill be devoted to the atmos-
pheric chemistry and reactions of the air pollutants.
I would like to announce (1 hope most of you have the blue folder with
today's program) that one paper will be added at the end of this morning's
session. It is a paper by Dr. Billings Brown, a chemist, being given
as a private citizen. The paper will be presented by Dr. Paul Brown; and
the subject is The Case Against Is Ox Standards.
Iv/ould now like to introduce- the new Assistant Administrator for
Research and D.'veinp.nent o; tho Envlronnieiiua Protection Agency,
Dr. V/nson T-alley.
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DR. WILSON K. TALLEY
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DR. WILSON K. TALLEY
ASSISTANT ADMINISTRATOR FOR RESEARCH AND DEVELOPMENT
ENVIRONMENTAL PROTECTION AGENCY
FEBRUARY 10, 1975
I am pleased to welcome you to the Scientific Seminar on Automotive
Pollutants. We have come together here to fill a very special need, that
is the need for the very latest research information to contribute to the
EPA's hearings on Suspension of the 1977 Model Year Standards for Auto-
motive Emissions.
More specifically, the purpose of this seminar is to provide a scientific
forum for both the presentation and discussion of recent research on the
health effects and atmospheric characteristics and processes of auto emissions,
paTlicxilurly NO;: and carbon monoxide.
The seminar emphasizes NOx because it participates in a complex manner
with photochemical oxidant formation and with hydrocarbons. We are including
carbon monoxide because it is a significant auto emission and is the subject
of some very recent health effects research.
A necessarily related theme of the seminar is the atmospheric chemistry
and physics of auto pollutants. The interest here, of course, is in that
aspect of the NOx chemistry pertaining to the role of NOx and photochemical
air pollution problems, With such problems, the oxidants and the NOx
problems are well recognized and control strategies are being developed.
Other problems, such as those from the toxic and visibilit}' reducing nitrates,
are much less understood. Therefore, any information on the role of NOx
in such problems, and more specifically on the impact that increase or-
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decrease of NOx emissions would have on urban and non-urban air quality,
is precisely what we hope to discuss in this seminar.
It is understood, of course, that since NOx is not the sole precursor of
the photochemical pollutants, the role of NOx must be of necessity examined
in conjunction with the role of hydrocarbons.
We are aware that many papers will be heard in these three days, that
they represent preliminary opinions. This seminar is a research in pro-
gressive type meetings, bringing together some of the very latest research
on very complex issues.
Our exchange of information and exposure to each other's views are the
keys to this meeting, and we need many more like it. We, therefore, hope
and expect and will encourage discussion.
I would like to announce at this time that issues related to atmospheric
]ovclr. and-,ad"£rn3 .health effect:: of sulfato emissions from, automobiles will
be discussed at a continuation of the suspension hearings that were recessed
last Friday, and will begin again February 18.
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B. DR. JAMES PITTS
AIR POLLUTANTS & PUBLIC HEALTH:
OLD PROBLEMS & NEW HORIZONS FOR
NOx CONTROL
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"Air Pollutants and Public Health: Old Problems
and New Horizons for NOX Control"
by
James N. Pitts, Jr., Ph.D., Director,
Statewide Air Pollution Research Center
University of California, Riverside
presented at the
EPA SCIENTIFIC SEMINAR ON AUTOMOTIVE POLLUTANTS
Washington, D. C.
February 10-12, 1975
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"Air Pollutants and Public Health: Old Problems
and New Horizons for NOV Control"
A
James N. Pitts, Jr., Ph.D.
Introduction
Dr. Wiser asked me to lead off this three-day seminar with an "overview"
of the problem, including some indication of where we were, where we are nov.,
and perhaps where we should be in this complex and highly relevant area of
atmospheric chemistry and its relationship to the control of automotive pol-
lutants, particularly oxides of nitrogen (NOX). I shall try to do this
(although I'm not sure how this can be accomplished in the prescribed twenty
minutes), but with the very clear understanding that the real "pros" in
health effects will be lecturing this afternoon and tomorrow morning, and
many expert atmospheric chemists will be speaking tomorrow afternoon and
Wednesday. Details and other points of view will be given in depth then.
Today, I can only illustrate what I personally consider to be some of
the highlights of this very important problem. Admittedly, I speak with a
certain amount of personal interest, because I live at the eastern end of
California's South Coast Air Basin (SCAB). My comments will be set in the
context of Mr. Train's opening remarks, stressing the prime need to consider
public health and welfare in all deliberations and actions. I should add
that the views I express are not necessarily those of the University of Cali-
fornia.
We shall begin with a "statement of the problem," and then discuss the
t
nature and magnitude of some of the chemical and physical effects relevant
to atmospheric chemistry, health effects, and the NO control issue. I will
A
use the South Coast Air Basin as a prime example, because the characteristics
of gas-to-particle conversion processes, such as S09 to sulfate and NO to
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nitrate aerosols, as well as the accompanying formation of ozone,that occur
in photochemical smog, have been examined in detail in mission-oriented
programs funded by California's Air Resources Board (ARB), the EPA, NSF-RANN,
and other groups such as the Coordinating Research Council.
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Statement of the Problem
Figure 1 illustrates the nature of the "beast," photochemical smog--
it is not a photograph of southern California, as you might expect, but of
San Jose, California, September 10, 1971. This picture was taken on a flight
conducted as a part of a joint research program on monitoring ambient pollu-
tant levels in "3-D"—vertically as well as horizontally. It was carried
out by a joint NASA-Ames, UC Statewide Air Pollution Research Center (SAPRC)
team that I was privileged to be a part of.
We flew this mission in a Cessna 401, going in and out of that polluted
air mass. Visibility was "zilch" when we dipped below the inversion. Indeed,
it seemed to us that it must have been an airline pilot who wrote the popular
song, "Do You Know The Way To San Jose?"
This photograph clearly illustrates that when one deals with the atmos-
pheric chemistry or health effects of smog, one is involved with an incredibly
complex heterogeneous mixture—one must think heterogeneous!
Among the questions we must ask are: "What are the gas-to-gas, gas-to-
liquid, gas-to-solid, liquid-to-liquid, liquid-to-sol id, and sol id-to-solid
interactions that occur" and "What are their effects on man and his environ-
ment, including agricultural crops and food production?" We must ask not
only "What are the mechanisms of the interactions?" but also "What are the
pollutant levels and what are their possible health effects—alone and
synergistically?"
p
The next figure, taken from a recent article by Mr. Larry Pryor in
the Los Angeles Times, illustrates transport of a polluted air mass across
the South Coast Air Basin. These are results of a study conducted by
Metronics, Inc., and funded by the ARB. Fluorescent tracers were released
at several points in the west and southwest, and their transport across the
Basin was determined from the number of tracer particles collected at spe-
cific receptor sites. It is significant that in one day some of the tracer
material introduced into the stack of a fossil fuel power plant in Long
o
Beach wound up far across the Basin, over 70 miles east of the source.
This Metronics study, along with recent extensive 3-D airborne monitor-
ing studies by Meteorology Research, Inc. (funded by the ARB and the EPA)
and the Los Angeles Reactive Pollutant Program (LARPP) study, clearly proves
*
that transport of pollutants emitted in the western end of the Basin can
impact on cities far to the east on a time scale much less than some have
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San
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predominant trajectory
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believed. Also, ARB-funded studies, including those under the ACHEX
(Characterization of Aerosols in California) cooperative program and that
of Dr. Cahill's team at the University of California in Davis, show that
under conditions of high levels of photochemical oxidant, the rate of
oxidation of sulfur dioxide to sulfate particles may be as fast as 5 to 10
percent per hour! While this is a fascinating subject, in view of the time
limitation and thrust of this seminar, I will not comment further on studies
of SCL-sulfate conversions.
Furthermore, as we shall see in more detail later, under these "smoggy"
conditions, oxides of nitrogen, NO, and NOo emitted in the western or central
part of the Basin will be substantially oxidized while being transported in
an easterly direction to Pomona, San Bernardino, etc. Thus, on a "bad" day,
high ambient levels of nitrate aerosols are formed in a series of complex,
secondary processes concurrently with high levels of ozone.
I want to stress today, since we are focusing on alternate NO control
A
strategies, how important it is to understand the atmospheric transformation
of gaseous NO to particulate nitrate, which includes as intermediate steps
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the possible formation of nitrous and nitric acids, organic nitrates such
as the PAN family, etc. It is also important to measure (ideally concur-
rently) the ambient levels of these species, as well as the nitrate and
sulfate particulate loadings at various stations across any air basin in the U.S.
suffering from elevated levels of photochemical smog.
In this context, let me restress a major conclusion from the ACHEX
study; by the time a polluted air parcel moves across the SCAB, under condi-
tions conducive to intense photochemical smog formation, nitrate aerosols
(probably mostly in the form of ammonium nitrate) form a very substantial
contribution to the particulate loading. Furthermore, most of this secondary
aerosol falls in the submicron size, respirable range, where it has maximum
effect in reducing visibility and affords maximum penetration into our lungs.
As I stated earlier, I do not know the health effects of ammonium
nitrate aerosols; they will be discussed later today. However, one major
conclusion is clear: in areas suffering from significant photochemical smog,
control of oxides of nitrogen will certainly reduce ambient levels of NOp,
PAN, nitric acid, and other such gas phase organic and inorganic pollutants,
as well as the nitrate aerosols which, to repeat for emphasis, seriously
reduce visibility and which may have significant health effects on man.
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Moving on, I would like to raise a question often asked by legislators
and the public—one that is relevant to the role of NO in control of
y\
oxidant: "How effective have the past and present control strategies been
to reduce oxidant in California?"
The most recent Los Angeles Air Pollution Control District (LAAPCD)
Digest, dated January 1975, stated "Los Angeles County air quality continued
an improving trend in 1974." On the other hand, only a few days later,
front-page headlines in the Los Angeles Times, February 3, stated,"LA Air
Quality Declines," and the article, by Mr. Larry Pryor (based on ARB aero-
metric data), goes on to say, "Air quality in LA Basin got worse in 1974."
I am not simply trying to illustrate a conflict of views, but I want to
indicate that perhaps one might reach different conclusions, depending upon
where (and how) one looks at the air quality—whether it's in downtown LA or
whether it's in Pasadena or suburban areas to the east. This is a point
relevant to later talks on the effects of NO reductions on oxidant levels
A
in the "central city," and downwind in the suburbs and ultimately the rural
areas. For example, the oxidant situation over a number of years in San
•*•
Bernardino, California (at the eastern end of the SCAB), is shown in Figure
3, which is taken from an article by Mr. William Greenburg in the San
Bernardino Sun-Telegram and based on data from the San Bernardino Air Pollu-
te
tion Control District. The graph shows the number of hours in which the
oxidant readings were greater than 0.2 ppm--our First-Stage Alert in Cali-
fornia.
The value of 296 hours over the California First-Stage Alert in 1970
dropped dramatically to a low of 60 hours in 1972, then in 1974 rose to 396--
the worst in the past 12 years.
I want to stress, however, we must be very careful to consider meteoro-
logical effects, including long-range transport of 03 and its precursors, on
ambient 0^ levels before making overly positive statements that the oxidant
problem in-a given air basin is getting better or worse with time. Dr. John
Kinosian, of the ARB, may be speaking about this point tomorrow.
Some Aspects of the Chemistry of Photochemical Smog Formation and Its
Relevance to NOX Control Strategies
1) Atmospheric Chemistry and Smog Chamber Studies
So much for the "statement of the problem." Now let's briefly
review some highlights of the chemistry of the NOx-HC-air system. Detailed
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treatments are given elsewhere.
Figure 4 presents the broad features of photochemical smog formation
in a typical chamber experiment. The hydrocarbon, propylene, is steadily
oxidized to products, including PAN and aldehydes. Nitric oxide (NO) is
rapidly converted to N02, and 03 begins to form after an initial induction
period, the duration of which is largely controlled by the initial NO con-
centration. Figure 5 shows that most of these features also occur in a
polluted urban environment. It is the goal of atmospheric scientists to
explain, in detail, the shapes of curves such as those in Figures 4 and 5
and then to translate this knowledge into technically sound control strate-
gies. To date, from the point of view of NO and HC control strategies,
/\
considerable emphasis has been placed on these phenomena.
However, I want to restress here that a multitude of other toxic, or
possibly toxic, gases and aerosols are formed concurrently with ozone. A
very complex mixture is produced! Furthermore, in contrast to ozone and
NOg, we do not have primary air quality standards for these compounds, which
include nitrous acid, nitric acid, PAN and other organic nitrates, particu-
late nitrate, etc.
Thus, it is extremely important that when v/e look at NO control
A
strategies, we do not focus solely on reducing ozone or N02. Instead, we
must examine the impact of either increasing or relaxing the degree of NO
A
control on the entire spectrum of species that might in one way or the other
have significant effects on our health.
18
Traditionally, smog chambers have been employed to elucidate in part
the chemical and physical transformations occurring in photochemical smog
formation, and data generated in smog chamber experiments have formed the
19-21
bases for various control strategies. Now, to be somewhat specific
and to introduce some of the current research by our SAPRC "team" (who,
incidentally, do the real work ... I just talk about it at seminars), I
want to briefly illustrate the utility of smog chamber data for control
strategy formulation. (Dr. Dimitriades will be talking about chamber
studies in much more detail later.)
22
Figure 6 shows a diagram of our SAPRC evacuable chamber. It is
about 13 feet .long and 5 feet in diameter, with fused silica windows and
a White cell-type multiple pass optical system for long-path infrared
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CONCENTRATION (ppm)
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TEMPERATURE CONTROL MANIFOLD
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spectroscopy. Design and construction of the SAPRC chamber facility was
originally funded by the ARB; currently, air pollution research is supported
by the ARB, EPA, and NSF-RANN. A photograph of this chamber is given in
Figure 7.
With this particular chamber, one can obtain data useful for modeling
studies, which are taken under precisely controlled conditions and under
realistic ambient concentration levels. However* I would caution all
physical scientists and medical researchers alike that there is no such
thing as a truly "clean smog chamber." One always has wall effects, to a
greater or lesser degree, which are unavoidable. Just as in the real world,
we can't get entirely away from wall effects, even in our evacuable chamber.
This is a major problem in the "chamber game," but it's the only game we
have to play at the present time.
It has become more and more important to recognize that in smog
chamber studies one should use light sources that will emit, and windows
that will fully transmit, a faithful simulation of solar ultraviolet radia-
tion, particularly in the region from 2950 to 3200 ft, since several important
smog reactions occur in that short wavelength actinic region. If one only
uses fluorescent black light irradiation or chambers with certain windows
that cut off transmission at, say 3100 to 3200 A, one may not observe
certain photochemical processes which, in fact, are significant in the real
polluted troposphere.
23
For this reason, we designed and constructed a solar simulator with
a 25,000-wattshort-arc, high-pressure Xenon lamp as the source. A diagram
of the simulator is given in Figure 8. It delivers a collimated, uniform
light beam about 5 feet in diameter. There is no time for further details,
but I will note that with this system and the fused silica chamber windows,
we are actually energy-rich in the short actinic UV. Thus, essentially, we
have a "true sun."
While Figure 4 shows typical time-concentration profiles, for a single
hydrocarbon one cannot model relationships between ozone dosage and the reac-
tive hydrocarbon*/NO ratio in real or simulated atmospheres. Other papers
/\
will be treating this important question in detail, so I will only show one
figure displaying our latest results. These studies were conducted in our
second chamber—an all-glass reactor with "black" fluorescent lights. It is
*Reactive hydrocarbons are defined as all non-methane hydrocarbons (NMHC).
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PUMP
OPTICAL INTEGRATOR
SECONDARY MIRROR
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However, the case of real, immediate interest is neither HC or NO control
X
filled with air containing NO and a complex mixture of hydrocarbons designed
A
to mimic those present in actual polluted atmospheres. A photograph of this
particular chamber is shown in Figure 9.
24
The experimental results from this chamber, shown in Figure 10,
illustrate some of the problems associated with developing control strate-
gies with the hydrocarbon-NO -ozone system. It is a classic case of "I've
A
got good news and bad news." This is evident from examining these curves,
which are plots of 6-hour maximum ozone levels (values after 6 hours of
irradiation) vs. initial NO concentration—at several concentrations of
J\
this surrogate mixture of hydrocarbons. One can see that as one lowers the
initial NMHC concentration while holding a constant initial NO level, the
A
ozone levels always decrease. Clearly, strict control of reactive hydro-
carbons is crucial for the reduction of ambient 0.,. However, if one main-
tains a constant initial hydrocarbon level and reduces the initial NO , and
A
if one is on the high NO side of the maxima (where most current ambient
A
levels in the SCAB occur), we see that NO reduction results in an increase
X
in maximum 6-hour ozone levels, or ozone dosage.
However, the case of real, immediate intere:
alone, but what trade-offs are involved in simultaneous reductions in HC and NO
X
levels. Thus, for example, we have very recently been applying these chamber
data to this question in connection with the NO retrofit control program for
25
1966-70 light-duty vehicles in California's SCAB. From this study, we have
concluded that for the specific reductions in HC and NO emissions which are
A
expected from the complete implementation of this program, of the order of 5%
each, np_ increase, and indeed a decrease of up to 5%, in maximum ozone levels
should occur in the SCAB in 1975. The most significant decrease is likely to
occur in the downwind receptor areas. Perhaps even more importantly, as dis-
cussed above, the reduction in NO due to the retrofit program also will result
X
in reduced ambient levels of toxic, gas-phase nitrogenous compounds, such as
the PAN's, as well as of nitrate aerosols.
Finally, while the effects of this particular retrofit program are rela-
tively small, as the Technical Advisory Committee to California's Assembly
Transportation Committee recently noted, "Progress in improving air quality
further will be accomplished by the combined effects of a number of well-planned
cost-effective" programs ,.. each of modest impact but significant*in the aggregate."
2) Alternate Approaches to Control Strategies
To move to another aspect of oxidant control strategies, I would like to
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SIX-HOUR OZONE (ppm)
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8
make a suggestion, which is relevant to the example just cited and which I
believe merits some consideration, hopefully by you, Mr. Train, and your staff.
?fi
Basically, it is this. It has been my opinion that we should not focus
simply on control strategies designed strictly to meet the provisions of the
1970 Clean Air Act, permitting no more than one day per year of oxidant to
exceed 0.08 ppm. It is absolutely essential that along with the overall imple-
mentation plan, we also develop and implement short-term control programs
designed specifically to reduce significantly the days of high oxidant concen-
trations and dosages—the really dangerous days that, for example, are all too
coranon in the SCAB. Thus, recently a number of medical researchers have stated
that their prime immediate concern is reducing the cumulative dosage and fre-
quency of short-term peak maxima, e.g., over 0.3 and 0.4 ppm, of 0.,.
In this context, the question posed is "What controls would be necessary
to reduce ozone levels in Pasadena or Pomona to no more than one day per year
of over, say, 0.2 ppm?" Or, at an even higher priority, "What would it take
to arrive at no more than one day per year over 0.3 ppm of 03 anywhere in the
South Coast Air Basin?"
In short, we should have, along with our overall strategy designed to
reach the Clean Air Act goal of no more than one day per year over 0.08 ppm
oxidant, some short-term, achievable control strategies designed to reduce
significantly the medically dangerous days with high oxidrnt values.
3) 6as-to~Particle Conversion Processes in Photochemical Smog
Figure 11 again shows the real world situation and illustrates what
I mean when I talk about particulates. The photograph, taken by Dr. Edgar R.
Stephens in Riverside, California, March 16, 1972, shows what photochemical
smog looks like on bad days. The total oxidant reached 0.4 ppm (a Second-
Stage Alert) later that day.
It is interesting that in the winter months and early spring, when 03
levels are significantly below the maxima of summer and fall, the eastern and
southeastern portions of the Basin are often subject to relatively high levels
of PAN, and, in this particular air parcel, there was a high concentration of
this toxic compound. This picture, and that of San Jose (Figure 1), illus-
trate clearly why people in California are very concerned about particulates.
In this regard, let.me quote some of the conclusions derived.from a
preliminary draft of the very important ACHEX report. I mentioned earlier
that this was a field research program funded by the California ARB. The
-------
-------
program was managed, and the final report prepared by Dr. George Hidy, of
the Rockwell International Science Center, with a distinguished list of co-
workers. It was a highly complex cooperative program of research involving
a number of laboratories—industrial, agency, and university. I should add
parenthetically that I was not involved personally with this program. It
represents a first-class, monumental effort, and I am pleased the preliminary
draft of the first summary has been released by the ARB. I quote as follows:
"An analysis and interpretation of observations taken between 1971 and
1973 show the great importance of haze formation as a secondary process in
urban air resulting from chemical reactions of S07 to produce sulfate, NO
£• A
to produce nitrate, and hydrocarbon vapors to produce organic particulates.
"These conversion processes are enhanced in the polluted atmosphere by
photochemically related reactions and involve ammonia and water in the air.
The conversion of these constituents results in aerosol particle growth in
the range of size most significant for visibility degradation and health
hazard.
"The data analysis suggests that generally more than half" -- now this
is the crucial point -- "generally more than half of the aerosols sampled
over the Los Angeles area is of a secondary origin."
They go on to say, "To achieve the existing ambient air quality
standards for aerosols in the South Coast Air Bain, controls on SOX, NOX,
and certain hydrocarbon vapor emissions will be required.
"Arguments are presented that identify SO emissions mainly with
A
stationary sources, while NO and hydrocarbon emissions are linked primarily
A
to transportation sources." I should add, however, that since this came out,
a detailed emissions study of NO emissions in the SCAB has been released.
A
It was carried out by the KVB Company, under ARB auspices. It makes the
point that there are also substantial contributions from stationary sources
in the LA Basin. Indeed, they state that if the NOV control programs on
A
automobiles are carried out as currently scheduled, by the early 1980's
stationary sources will contribute as much to the NO burden in the Basin
• A
as will automotive emissions. Thus, it is very important to keep a balanced
view as to the relative, and absolute, contributions from these two types of
sources, as well as area sources.
The ACHEtf report concludes that, "In the western portions of-the Los
Angeles Basin, visibility is degraded largely by stationary sources. In the
central area, there is roughly an equal source contribution to visibility
-------
10
reduction. On the eastern side, primary emissions and transportation sources
are deduced to be largely responsible for poor visibility." Please remember
that poor visibility also implies particles in the size range that will also
have maximum impact on public health.
Let me give you one last comment relating to some of the aerosol con-
centrations they observed in their studies.
"During the period of the studies (July-October 1972 and 1973), the
conditions in the South Coast Air Basin were by far the most severe with the
heaviest aerosol concentrations in the central and eastern parts of the Basin.
In moderate to heavy photochemical smog, as measured by hourly average oxi-
dant concentrations exceeding 0.30 ppm, individuals may experience total
loadings in excess of 250 micrograms per cubic meter aerosols, over two-hour
periods. Similar mass concentrations over 24-hour periods also have been
observed.
"Accompanying such levels, sulfate and nitrate concentrations as high
as 71 micrograms per cubic meter of sulfate and 247 micrograms per cubic
meter of nitrate in two-hour periods were observed."
I might add that at that particular station, the 24-hour average for
the study period was reported to be 19.2 micrograms per cubic meter of
nitrate aerosols.
Finally, I would make one more comment. That is, in addition to looking
at nitrate particles, may I stress the importance of trying to identify and
measure levels of such inorganic and organic nitrogenous compounds as nitrous
acid, nitric acid, PAN, ethyl nitrate, etc., in irradiated simulated atmos-
pheres and in actual ambient air.
In this regard, we now have at the SAPRC, a Fourier-type infrared
spectrometer, funded by NSF-RANN and the State of California. It is mated
to the evacuable chamber so that we can look for such gaseous compounds, not
only in simulated atmospheres in the chamber, but also in ambient air, while
simultaneously carrying out detailed analyses of particulates. The diagram
27 28
of the apparatus and some typical spectra ' for a propylene-NO -air system
A
are shown in Figures 12, 13, and 14. Note the presence of such compounds as
MONO, HON02, PAN, ethyl nitrate, etc. While this run was not done under
actual ambient conditions, the results strongly suggest the urgent need for
such studies.
Dr. Wiser, when you phoned me recently, you also asked me to comment
on the oxidant measurement controversy. Unfortunately, my assigned 20
-------
EVACUABLE
ENVIRONMENTAL
CHAMBER
In Situ
MULTIPLE
REFLECTION
OPTICS
EOCOM 7101
FOURIER
SPECTROMETER
TAPE DECK and
CONTROLLER
-------
NO -6.2ppm
PHOTOLYSIS OF; N0z-3.8ppm
C3Hg- 7.8 ppm
60 meters PATHLENGTH
0.125 cm"1 RESOLUTION
MONO
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-------
NO
PHOTOLYSIS = N02
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3.8 ppm
7-8 PPm
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(cm ')
-------
140 i-
120 -
or
55 100
LU
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>: 60
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40
20
0
NUMBER OF DAYS IN 1973 FOR WHICH THE
MAXIMUM OXIDANT HOURLY AVERAGE >0.20 ppm
LOS ANGELES
PASADENA
POMONA
AZUSA
RIVERSIDE
SAN BERNARDINO
PRESENT METHOD
( DATA AS REPORTED )
Q
LA APCD METHOD
/RIVERSIDE, SAN BERNARDINO\
\DATA x 5/7
/
ARB METHOD
/LOS ANGELES DOWNTOWN, PASA-
V DENA, AZUSA, POMONA DATA x 7/5
b
-------
11
minutes are up. However, if any of you in the audient want me to comment on
this, please do so in the question-and-answer period, because Herb is going
to throw me off now!
Thank you.
Discussion
Dr. Wiser: I will open the floor to discussion. Please identify your-
self.
Mr. Lombardo: Louis Lombardo, Public Interest Campaign.
Dr. Pitts, when you also addressed this question of the oxidant
measurement controversy between LA County and the ARB, I would also appre-
ciate it if you would comment on the question of whether or not there was
any public participation in the review of that controversy.
Dr. Pitts: I will comment on it now.
Here is the origin of the controversy. Up until last June, if you had
asked me, "As a parcel of smoggy air moves from west to east, are oxidant
levels getting higher?" my answer would have been, "Yes." This would have
been in conformity with the following statement in a recent National Academy
29
of Sciences report.
"Thus, over a period of hours the mass of smog-laden air from downtown
Los Angeles experiences a growth in ozone concentration as it travels east-
ward so that a shift in maximum ozone concentrations eastward should be
expected, and has been confirmed by measurements.. The shift in ozone concen-
trations to the east also has been enhanced by the growth in urbanization in
that region, which causes increases in local hydrocarbon and NO emissions."
J\
In short, based on the monitoring data taken across the entire air basin,
it was generally believed that as the Los Angeles urban plume moved to the
east, ozone levels increased. Typical data for downtown LA, Pasadena, Azusa,
Pomona, Riverside, and San Bernardino are shown in Figure 15a. This shows the
number of days in 1973 for which the maximum hourly average of oxidant was
30
greater than 0.20 ppm.
It Was not until June 1974 that it was generally learned that the
calibration procedure of the ARB (employing the 2% neutral buffered KI [NBKI]
differed significantly from that used by the LAAPCD and that in parallel runs
in ambient air. the ARB obtained ambient oxidant values consistently about
30-35 percent higher than the LAAPCD. Unfortunately, stations in
-------
12
Los Angeles County, such as downtown LA, Pasadena, Azusa, and Pomona, used
the LAAPCD techniques, and in Riverside and San Bernardino Counties oxidant
levels were determined by the ARB method. (The latter is similar to the EPA
reference method, which employs 1% neutral buffered KI solution for calibra-
tion.) Now let's see what happens to these data if one puts all stations in
LA, Riverside, and San Bernardino Counties on one consistent data base.
First, let's assume the LAAPCD method is correct and lower the Riverside
and San Bernardino values accordingly—the results are shown in Figure 15b.
The results are interesting! They show that if one reduces the River-
side and San Bernardino oxidant data to be consfstent with the LAAPCD values,
the number of days when 0.20 ppm oxidant for one hour was exceeded in 1973
was greater in Pasadena, Azusa, and Pomona than in Riverside and San Bernar-
dino.
Now, let's assume the ARB 2% NBKI calibration method is correct. We
leave Riverside and San Bernardino data unchanged and increase the Los
Angeles, Pasadena, Azusa, and Pomona levels by a factor of 1.4. In Figure
15c, one again sees a complete reversal of the so-called "eastern maximum"
trend. Indeed, this is true for aerometric data for all years up to, and
including, 1973. (I should add, however, it may not be true for 1974.
Dr. Kinosian may also speak to this point.) Clearly, it is extremely impor-
tant that one has a consistent set of measurements across an entire air
basin, regardless of political jurisdictions!
The EPA is also involved with this problem--indeed, we are all involved.
To repeat, it is crucial that control strategies, health-alert levels,
emergency action plans, etc., all be based on an accurate and consistent set
of monitoring procedures.
As an example of the type of problem that can arise when there is not
a consistent monitoring program across political jurisdictions, we recently
had a case where the Kaiser Steel Company in Fontana was going into a partial
shutdown because the oxidant level exceeded 0.40 ppm, a Second-Stage Alert.
Actually, if the plant had been located a few miles away in LA County,
instead of the oxidant being 0.40 ppm, it would have been read as 0.28 ppm
oxidant--and no Second-Stage Alert would have been called.
We also have commonly experienced cases where school children were called
indoors becaus'e of first^stage alerts in Riverside and San Bernardino Counties,
but where a short distance away in LA County, they were allowed to exercise
outside as no alert was called.
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13
I'm not saying which agency is right or wrong in this debate, but only
want to stress the need for a consistent approach. This has been well
recognized by the ARB and the'LAAPCD, and a special ARB Study Committee has
been examining the matter. All that can be said at this time is that many
aspects of the 0, calibration problem are still perplexing, to say the least.
I believe it is urgent, Mr. Train, that the EPA, the ARB, the LAAPCD, the
National Bureau of Standards, and other interested and involved organizations,
such as the SAPRC, get together very soon to look at this monitoring problem
and devise a rational program for clarifying and resolving the present
discrepancies. As Ben Franklin once said, "We must all hang together in
this matter, or most assuredly we shall all hang separately."
Finally, I should add that the problem isn't just confined to oxidant.
Recently, I learned that a substantial number of instruments used to cali-
brate field instruments monitoring NO and N(L are, in turn, calibrated by a
gas-phase titration with a "standard" ozone stream. Unfortunately, the
latter is calibrated against neutral buffered KI so that if the KI technique
is wrong by, say, 20 percent, one's NO and NO- measurements will be off by
20 percent. (I should note that this consistency problem apparently does
not arise with totally EPA-supervised monitoring programs.)
In short, it is a very difficult task to measure accurately many air
pollutants at low ambient levels and in such complex mixtures, but we must
all use a consistent approach.
Did I answer your question?
Mr. Lombardo: Participation?
Dr. Pitts: It was an enterprising reporter, named William Greenburg,
of the San Bernardino Sun-Telegram, who broke this story. There was then a
great deal of public discussion and participation. Indeed, as I said
earlier, the ARB set up a Special Committee to examine the problem, and they
should make their final report soon. Unfortunately, it appears that their
report also will be highly controversial I
In short, I can assure you that the public was alerted, because the
problem was well covered in the press.
Thank you.
Dr. Wiser: Thank you, Jim, for an excellent overview into the purpose
of this meeting.
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14
REFERENCES
1. H. R. Gloria, G. Bradburn, R. F. Reinisch, J. N. Pitts, Jr., J. V. Behar,
L. Zafonte. "Airborne Survey of Major Air Basins in California," J. Air
Pollut. Cont. Assoc., 24_, 645 (1974).
2. L. Pryor. "Polluted Air Moves Far, Wind Pattern Variable, Study Finds,"
The Los Angeles Times, August 28, 1974.
3. L. M. Vaughan and A. R. Stankunas. "Field Study of Air Pollution Trans-
port in the South Coast Air Basin," Tech. Rept. No. 197, Metronics Asso-
ciates, Inc., Palo Alto, California, July 1974.
4. D. L. Blumenthal, W. H. White, R. L. Peace, and P. B."Smith. "Determina-
tion of the Feasibility of the Long Range Transport of Ozone or Ozone
Precursors," Meteorology Research, Inc., EPA Contract No. 68-02-1462,
November 1974. [Prepared for Environmental Protection Agency, Office
of Air and Waste Management, Office of Air Quality Planning and
Standards, EPA-450/3-74-061.]
5. "Characterization of Aerosols in California (ACHEX). Interim Report for
Phase I Covering the Period October 25, 1971 to April 1, 1973."
Submitted to the Air Resources Board, State of California, in partial
completion of research under ARB Contract No. 358. Prepared by G. M.
Hidy et al., Rockwell International Science Center, Vol. 1, Summary,
September 30, 1974.
6. Los Angeles County Air Pollution Control District Digest. "High Smog
Levels Absent in "1974, First Year Without .50 ppm Ozone," Vol. V, No. 1,
January 1975.
7. L. Pryor. "L.A. Air Quality Declines," The Los Angeles Times, February 3,
1975.
8. W. Greenburg. "Smog Season Worst on Record in S.B.," San Bernardino
Sun-Telegram, October 5, 1974. [Statistics compiled by San Bernardino
County Air Pollution Control District, Mel Zeldin, Meteorologist.]
9. P. A. Leighton, Photochemistry of Air Pollution, Academic Press, New
York, 1961.
10. J. N. Pitts, Jr. "Photochemical Air Pollution: Singlet Molecular Oxygen
as an Environmental Oxidant," in Advances in Environmental Science and
Technology, Vol. 1, J. N. Pitts, Jr., and R. L. Metcalf, eds., John
Wiley and Sons, Inc., New York, pp. 289-337, 1969.
11. C. S. Tuesday, ed., Chemical Reactions in Urban Atmospheres, American
Elsevier, New York, 1971.
12. J. G. Calvert. "Interactions of Air Pollutants," in Proc. Conf. Health
Effects of Air Pollutants, National Academy of Sciences, pp. 19-101,
October 3-5, 1973.
-------
13. K. L. Demerjian, J. A. Kerr, and J. G. Calvert. "The Mechanisms of
Photochemical Smog Formation," in Advances in Environmental Science and
Technology. Vol. 4, J. N. Pitts, Jr., and R. L. Metcalf, eds., Wiley
Interscience, New York, pp. 1-262, 1974.
14. J. N. Pitts, Jr., and B. J. Finlayson. "Mechanisms of Photochemical Air
Pollution," Angewandte Chemie, 87_, 18, 1975.
15. J. N. Pitts, Jr., A. C. Lloyd, and J. L. Sprung. "Chemical Reactions in
Urban Atmospheres and Their Application to Air Pollution Control Strate-
gies," Proc. Intern. Symp. Environmental Measurements, Geneva, Switzer-
land, October 2-4, 1973.
16. J. N. Pitts, Jr., K. L. Darnall, J. N. McAfee, J. W. Peters, J. P. Smith,
and A. M. Winer. Unpublished data, 1975.
17. "Air Quality Criteria for Photochemical Oxidants," USDHEW, National Air
Pollution Control Administration, Washington, D.C., AP-63, March 1970.
18. A. P. Altshuller and J. J. Bufalini. Environ. Sci. & Technol., 5, 39
(1971).
19. B. Dimitriades. "Effect of Hydrocarbon and Nitrogen Oxides on Photo-
chemical Smog Formation," Environ. Sci. & Techno!., 6_, 253 (1972).
20. W. J. Hamming and J. E. Dickinson. "Control of Photochemical Smog by
Alteration in Initial Reactant Ratios," J. Air Pollut. Cont. Assoc., 16,
317 (1966).
21. "A Critique of the 1975-76 Automobile Emission Standards for Hydrocarbons
and Oxides of Nitrogen," Committee on Motor Vehicle Emissions, National
Academy of Sciences, May 1973.
22. J. N. Pitts, Jr., P. J. Bekowies, G. J. Doyle, J. M. McAfee, and A. M.
Winer. ."An Environmental Chamber - Solar Simulator Facility for the
Study of Atmospheric Photochemistry," to be submitted to Environ. Sci.
& Technol. (1975).
23. J. H. Beauchene, P. J. Bekowies, J. M. McAfee, A. M. Winer, L. Zafonte,
and J. N. Pitts, Jr. "A Novel 20-KW Solar Simulator Designed for Air
Pollution Research," Proceedings of Seventh Conference on Space Simula-
tion (NASA Special Pub!. 336), Paper No. 66, pp. 811-825, November 12-14,
1973.
24. J. N. Pitts, Jr., A. M. Winer, K. R. Darnall, G. J. Doyle, and J. M.
McAfee. "Chemical Consequences of Air Quality Standards and of Control
Implementation Programs: Role of Hydrocarbons, Oxides of Nitrogen, and
Aged Smog in the Production of Photochemical Oxidant," Final Rept.,
California Air Resources Board, Contract No. 3-017, June 30, 1974.
25. K. R. Darnall, A. M. Winer, and J. N. Pitts, Jr. [In preparation, 1975]
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16
26. J. N. Pitts, Jr. Remarks before Subcommittee on Air and Water Pollution
of the U. S. Senate Committee on Public Works, Riverside, California,
November 16, 1973.
27. J. M. McAfee, J. N. Pitts, Jr., and A. M. Winer. "In-Situ Long-Path
Infrared Spectroscopy of Photochemical Air Pollutants in an Environ-
mental Chamber," Pacific Conference on Chemistry and Spectroscopy,
San Francisco, California, October 16-18, 1974.
28. A. M. Winer, J. M. McAfee, and J. N. Pitts, Jr. "Application of Long-
Path Infrared Spectroscopy in Studies of Photochemical Air Pollutants
at Ambient Concentrations," Twenty-Sixth Pittsburgh Conference on
Analytical Chemistry and Applied Spectroscopy, Cleveland, Ohio, March
3-7, 1975.
29. Air Quality and Automobile Emission Control, A Report by the Coordinating
Committee on Air Quality Studies, National Academy of Sciences, National
Academy of Engineering, Vol. 3, The Relationship of Emissions to Ambient
Air Quality, September 1974.
30. J. N. Pitts, Jr., J. L. Sprung, M. Poe, M. Carpelan, and A. C. Lloyd.
"Corrected South Coast Air Basin Oxidant Data: Some Conclusions and
Implications," [In preparation, 1975],
31. J. N. Pitts, Jr., J. M. McAfee, W. Long, and A. M. Winer. "A Long-Path
Infrared Spectroscopic Investigation of the 2% Neutral Buffered Potas-
sium Iodide Method for Ozone," to be published in Environ. Sci. &
Technol. (1975).
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FIGURE CAPTIONS
Figure 1. View of photochemical smog above San Jose, California, September 10,
1971, taken from Cessna 401-A aircraft used for air pollution
sampling in a joint NASA-Ames, UC-SAPRC study.
Figure 2. Tracer test summary, August 3-4, 1973, Long Beach source—elevated
to simulate industrial pollutants. Contours represent an effective
average concentration of tracer material from a normalized source
14
of 5 X 10 particles, released 0900-1500 hours, PST, on August 3
from a power plant stack. (Metronics Associates, Inc., Technical
Report No. 197, July 1974.3)
Figure 3. Number of hours per year for which the hourly average oxidant
concentration equaled or exceeded 0.20 ppm at San Bernardino air
monitoring station. (Data from San Bernardino County Air Pollution
Control District.)
Figure 4. Results of a typical smog chamber experiment, SAPRC's evacuable
chamber. Irradiation of a propylene-NO-NO^ mixture in the air.
Initial experimental conditions—0.5 ppm propylene, 0.42 ppm NO,
and 0.05 ppm NO^ in 760 torr of highly purified air.
Figure 5. Diurnal variation of NO, N02, and 03 concentrations in Los Angeles,
California, July 19, 1965.17
Figure 6. Schematic diagram of SAPRC's evacuable chamber at the University
of California, Riverside.
Figure 7. Photograph of SAPRC's evacuable chamber at the University of Cali-
fornia, Riverside.
Figure 8. Schematic diagram of the SAPRC's solar simulator, with 25-KW Xenon
short-arc source.
*
Figure 9. Photograph of SAPRC's 6000-liter, all-glass smog chamber.
-------
Figure 10. Six-hour ozone as a function of initial NO concentration for
A
four levels of initial non-methane hydrocarbons. Data obtained
in SAPRC's all-glass chamber.
Figure 11. View of photochemical smog, Riverside, California, March 16, 1972,
in which the maximum hourly oxidant concentration was 0.4 ppm.
[Photograph by Dr. Edgar R. Stephens, SAPRC.]
Figure 12. Schematic diagram of SAPRC's evacuable chamber and Fourier
interferometer with in-situ long-path optical system.
Figures 13 and 14. Results of in-situ long-path length Fourier interferometry
in SAPRC's evacuable chamber. Spectra obtained during photolysis
of propylene-NO -air system, showing presence of nitrous (MONO)
^ M
and nitric (HN03) acids, peroxyacetyl nitrate (CH3COON02), and
ethyl nitrate (C2H5ON02).
Figure 15. Number of days in 1973 in which the hourly average oxidant con-
centration equaled or exceeded 0.20 ppm at six air monitoring
stations in the South Coast Air Basin: (a) data as reported-
Los Angeles, Pasadena, Azusa, Pomona reported by Los Angeles
County APCD; Riverside reported by Riverside County APCD; San
Bernardino reported by San Bernardino County APCD; (b) non-LAAPCD
data multiplied by 5/7 to convert to LAAPCD scale; (c) LAAPCD data
multiplied by 7/5 to convert to ARB/EPA scale.
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C. MR. JOHN REDMOND
NAS REPORT TO THE SENATE COMMITTEE
ON PUBLIC WORKS - NOx HEALTH EFFECTS
-------
The report that I will summarize this morning was prepared as a
part of a task accepted by the Academy for the U.S. Senate Committee on
Public Works. The entire report on health effects has been published by the U.S.
Govt. Printing Office, as Air Quality and Automobile Emission Control,
a report by the Coordinating Committee on Air Quality Studies, NAS, NAE,
Volume 2, Health Effects of Air Pollutants. Serial No. 93-24, GPO
price: $4.35.
This report was prepared by a task force on health effects of nitrogen
oxides of the Panel on Nitrogen Oxides of the Committee on Medical and
Biological Effects of Environmental Pollutants.
The report consists of a summary which is an attempt to answer five
paragraphs of questions posed by the Committee on Public Works. This is
followed by 120 pages of documentation and discussion of the data on which
the answers were based.
Health effects of air pollutants are studied in animal models,
controlled laboratory exposure of humans and epidemiolr^ic investigation.
Animal studies have assessed pathologic, microbiologic and physiologic
effects of acute and chronic exposures to different concentrations of the
pollutant.
E. Summary of Experimental Animal Studies
The studies that have been cited document severe pulmonary disease
in animals that have been exposed acutely (for less than 24 hr) to very
3
high concentrations of nitrogen dioxide, 6.6 mg/m (3.5 ppm) or greater.
3
Mortality occurs when the concentration exceeds about 75 mg/m (40 ppm).
-------
-2-
Physiologic and pathologic abnormalities appear at concentrations above
3
9.4 mg/m (5 ppm) . Abnormalities in pulmonary microbial defense mechanisms
appear to be the most sensitive indicator of nitrogen dioxide-induced
3
injury; dysfunction occurs in mice after a 2-hr exposure to 6.6 mg/m
(3.5 ppm). Because these concentrations are much above ambient, their
relevance to daily environmental exposures is minimal.
More prolonged exposure to nitrogen dioxide causes minor, not life-
threatening abnormalities in mice, the most susceptible animal species,
3
at concentrations of 0.94 mg/m (0.5 ppm) or greater. All animal species
that have been studied (mice, rats, guinea pigs, dogs, and monkeys), can
survive exposures of a year or more to nitrogen dioxide concentrations of
0.94 mg/m (0.5 ppm) or greater. Some animal species, such as dogs and
guinea pigs, appear to be inordinately resistant to the lethal effects of
nitrogen dioxide; these animals withstand continuous exposures of a year or
3
more to 9.4 and 28 mg/m (5 and 15 ppm).
Before summarizing the pathophysiologic effects of prolonged exposure
to nitrogen dioxide, we should emphasize that these investigations have
3
used normal animals and that concentrations below 0.94 mg/m (0.5 ppm) have
only rarely been studied. The available evidence demonstrates that contin-
3
uous exposure to nitrogen dioxide at 0.94 mg/m (0.5 ppm) causes minor,
not life-threatening, and sometimes self-limiting pathologic abnormalities
of ciliary loss, alveolar cell disruption, and obstruction of respiratory
bronchioles in mice and rats. Exposure to higher concentrations of nitrogen
dioxide results in more severe cellular and structural damage, which in
the rat and rabbit resembles emphysema.
-------
A variety of physiologic alterations (tachypnea, increases in airway
resistance, decreases in tidal volume and in static compliance) occur in
rodents and in nonhuman primates after prolonged exposure to nitrogen
3
dioxide at 9.4 mg/m (5.0 ppm) or higher. More serious abnormalities in
pulmonary function, such as decreases in blood oxygenation, occur in
i
rabbits after continuous exposure to 1.5 mg/m (8.0 ppm). These physiologic
data are relatively incomplete, in that measurements of small airway
function and of the effect of exercise have not been reported. These two
kinds of test measurement may be more sensitive indicators of pollutant-
induced dysfunction than the presently used physiologic measurements.
3
Prolonged exposure to nitrogen dioxide at 0.94 mg/m (0.5 ppm) and
higher diminishes murine ability to resist pulmonary bacterial and viral
infection. At higher exposures, 9.4 mg/m (5.0 ppm), similar results
have been reported for hamsters and nonhuman primates. These deficits in
microbial resistance have in some instances been associated with pneumonia
and death. Immunologic deficits unassociated with overt infection have been
3
observed after prolonged exposures to 1.8 mg/m (1.0 ppm). At present,
these investigations of the combined effect of nitrogen dioxide and infection
have provided the most sensitive indications of potentially significant
pollutant-induced damage.
A few studies are available in which animals have been exposed to a
mixture of pollutants, including nitrogen dioxide. Combinations of
nitrogen dioxide with carbon monoxide, ozone, or sulfur dioxide have usually
resulted in an additive or indifferent effect. Synergism has, with one
exception of uncertain significance, not been reported, and to our knowledge
antagonism has never been reported.
-------
-4-
o
In summary, continuous exposure to nitrogen dioxide at 0.94 mg/m
(0.5 ppm) causes minor abnormalities in pulmonary histology, physiologic
function, and antimicrobial defense mechanisms. Although there is no
experimental evidence that continuous exposure to lower concentrations of
nitrogen dioxide impairs any of these, definitive information is not
available.
Few studies of controlled exposure to human volunteers have been
reported. There have been brief (less than 1 hr) exposure to 0.5 - 5.0 ppm
nitrogen dioxide. These have demonstrated abnormalities of airway resist-
ance, compliance and arterial blood oxygenation after exposures to
1.5 - 5.0 ppm for 10 - 30 minutes.
The most complete epidemiologic studies of nitrogen dioxide were
the ones carried out in various communities in and around Chattanooga.
According to these data, exposure to nitrogen dioxide may increase human
susceptibility to respiratory infection. These findings have been con-
firmed in part by investigations in the Soviet Union. More continuing
epidemiologic studies are badly needed. Evaluation of the present air
quality standard of 0.05 ppm shows that it is consistent with the available
epidemiologic studies.
The disease condition implicated in the epidemiologic studies is an
increase in susceptibility to respiratory infection. From present
information, individuals with chronic respiratory disease, asthma, and viral
and bacterial pulmonary infections appear to have unusual sensitivity to
pollutants. The very young may also have an increased susceptibility to
pollutant damage.
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—S—
In conclusion, the report states that there are interrelations of
all the air pollutants to each other. They probably act biologically as
a group. As regards the present health standard for nitrogen dioxide,
the available data, including the most recently reported at the time of
the preparation of this report, indicate that the standard of 0.05 ppm
per year does afford reasonable protection from the risk of nitrogen
dioxide pollution in healthy, as well as inordinately susceptible,
individuals. Because brief, as well as continuous, exposure to nitrogen
dioxide has biological effects, a short-term hourly standard would seem
advisable.
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D. DR. CARL SHY
HEALTH RATIONALE FOR THE EXISTING
NITROGEN OXIDE EMISSION STANDARDS
-------
HEALTH RATIONALE FOR THE
EXISTING MOBILE SOURCE EMISSION STANDARD FOR NITROGEN OXIDES
Presented at the Public Hearing on Mobile Source Emission Standard
Washington, D.C., February 10-12, 1975
by
Carl M. Shy, M.D.
Institute for Environmental Studies
University of North Carolina at Chapel Hill
Chapel Hill, N.C. 27514
February 3, 1975
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INTRODUCTION
I am Carl Shy, a physician and research investigator on the human health
effects of air pollution. Presently I am Director of the Institite for Environmental
Studies at the University of North Carolina in Chapel Hill. I am a member of the
Panel on Nitrogen Oxides of the National Research Council - National Academy of Science
While employed by the U.S. Environmental Protection Agency, I conducted epidemiologic
studies on the health hazards of human exposure to nitrogen oxides and was involved in
writing the air quality criteria for nitrogen oxides. As a member of the aforementione
Panel on Nitrogen Oxides, I have been engaged in a scientific review and evaluation of
the health effects of nitrogen oxides.
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SUMMARY
In my presentation today, I will summarize the health evidence for maintaining a
trict motor vehicle emission standard for nitrogen oxides. I will argue that, to
rotect against the adverse health effects of short-term exposures to nitrogen dioxide,
one-hour exposure limit of 375 to 630 ug/m3 (0.20 to 0.34 ppm) is necessary. This
Kposure limit provides only a moderate margin of safety, that is from 50 to 100% below
lie threshold concentration at which adverse health effects may be anticipated. To
:hleve a one-hour exposure limit of 375 to 630 ug/m^, exhaust emissions for nitrogen
cides from motor vehicles should be limited maximally to 0.4 grams per mile or
Lnimally to 2.0 grams per mile. This range of emission control is a function of the
igree of concommitant control over nitrogen oxide emissions from stationary sources.
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EVIDENCE FOR ADVERSE HEALTH EFFECTS OF ONE-TIME NOX EXPOSURES
We have biomedical data that demonstrate adverse effects associated with
one-time short-term exposures and with repeated short-term exposures to NO?* In Table
1, I have cited three human studies which reveal significantly increased airway
resistance produced by one-time NO- exposures of 1300 to 3760 ug/m^ (0.7 to 2.0 ppm)
for 10 to 45 minutes.
Table 1. One-Time Exposures to
Causing Increased Airway Resistance in Humans
N02 Concentration Equivalent 1-hr. N0£ Concentration*
ug/m3 (ppm) Exposure Reference _ ug/m3 (ppm) _
1320-3760 (0.7-2.0) 10 min Suzuki (1) 742-2112 (0.39-1.12)
3000-3760 (1.6-2.0) 10-15 min. von Nieding 1685-2458 (0.90-1.31)
(2)
2820 (1.5) 45 min. Rokaw (3) 2518 (1.34)
*Based on Larsen's model (4) and assuming the maximum standard geometric deviation as
measured at CAMP sites. From this model, the ratio of N02 concentrations at 10 min.,
15 min., and 45 min. to the 1-hour concentration is 1.78, 1.53 and 1.12 respectively
The far right column of Table 1 shows the maximum 1-hour NOj concentration which
could be expected in the ambient atmosphere in association with the concentration and
averaging time given in the first two columns, assuming a standard geometric deviation
equivalent to the maximum value obtained at sites of the Continuous Air Monitoring
Program (CAMP). These distributions are calculated according to Larsen's model (4).
-------
Under these assumptions concerning the time-distribution of maximum N0£ concentrations,
an adverse human response as manifested by significantly increased airway resistance
would be expected from one-time nynHimnn one-hour NO^ exposures of 750 to 2500 ug/m3
(0.40-1.33 ppm). If we make the further assumption that the more susceptible and
reactive individuals in the population are likely to be affected at the lower end of
this range of concentrations, we could reasonably conclude that the one-hour N(>2
:oncentration at which earliest effects are likely to occur in susceptible populations
ipon one-time exposures is 750 to 950 ug/m3 (0.40-0.50 ppm).
EVIDENCE FOR ADVERSE HEALTH EFFECTS OF REPEATED
SHORT-TERM 1TCL. EXPOSURES
jL
Both human and animal data provide evidence for impairment of the body's resistance
o respiratory infections and for lung damange. These data are summarized in Table 2.
Table 2. Repeated Exposures to N02
Causing Impaired Resistance to Respiratory Infections
And/Or Tissue Damage in the Lung
Source of N0£ Concentration Duration of
Data ug/m3 (ppm) Exposure Reference
Humans 282-940 (0.15-0.50) 2-3hrs x 6 mos Shy, Pear Iman (5-7)
Mice 940 (0.50) 6 hr/d, 5 d/wk Ehrlich (8,9)
x 4-12 wks
Mice 564-940 (0.3-0.5) 6 mos. Chen (10)
Mice 940 (0.5) 3 mos. Freeman (11)
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-3-
In the above experimental studies on mice, the lowest N02 concentration causing
lung damage or impaired resistance to respiratory infections was not determined. The
stated concentrations (564-940 ug/m3) are the lowest non-zero exposures employed by
the investigators. Thus it is entirely possible that repeated exposures to short-
term N(>2 concentrations as low as 280 to 560 ug/m3 (0.15 to 0.30 ppm) could produce
in animals the earliest onset of the adverse responses definitely found at concentra-
tions of 560 to 940 ug/m3 (0.30-0.50 ppm). This conclusion is supported by the
results of the Chattanooga studies (5-7) in which significantly increased rates of
respiratory disease in children and adults were associated with long term N02 exposure!
of 150 to 282 ug/m3 (0.08 to 0.15 ppm) or with repeated 2-3 hour exposures of 282 to
940 ug/m3 (0.15-0.50 ppm).
These converging sources of evidence suggest that the threshold concentration for
adverse health effects associated with repeated short-term exposures to NC>2 is 282 to
940 ug/m3 (0.15 to 0.50 ppm), and that the more susceptible individuals in the popula-
tion are likely to react at the lower end of the range, namely, 282 to 560 ug/m-*
(0.15 to 0.30 ppm).
MARGINS OF SAFETY
The national primary standard for air pollutants requires that a margin of safety
be considered to provide a difference between highest allowable human exposures and
the effects-threshold. The range of allowable exposures based on a 50 percent or 100
percent (2-fold) margin of safety is given in Table 3 for one-time and repeated short-
term exposures to N0~.
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-4-
Table 3. Effects-Thresholds and Margins of Safety
for Human Exposure to Short-Term N0« Concentrations
O
Averaging Effects - Threshold Max. Allowable Exposure ug/m' (ppm)
Time ug/m3 (ppm) At Stated Margin of Safety
50% 100%
One-time, 1-hr. 750-950 (0.4-0.5) 500-630 (0.27-0.34) 375-475(0.2-0.25)
Repeated, 2-3 hrs. 280-560 (0.15-0.30) 188-373 (0.10-0.20) 140-280(0.08-0.15)
A margin of safety ranging from 50 to 100 percent would conform to safety margins
existing for other primary air quality standards (12). Thus, a maximum allowable
one-time exposure to N0~ for one-hour may reasonably be established at concentrations
between 375 and 630 ug/m3 (0.20-0.34 ppm). Using similar reasoning, maximum allowable
repeated exposures to N02 for 2 to 3 hours may be considered at concentrations between
140 and 373 ug/m3 (0.08-0.20 ppm).
While these judgments are based on moderately conservative estimates of the
threshold concentration for adverse responses in susceptible segments of the population,
they do not take into account the potential for further ill effects due to transforma-
tion products of N02 in the atmosphere. These transformation products include nitrate
salts, and nitrous and nitric acid aerosols. Studies recently completed by the
Environmental Protection Agency have associated airborne nitrates with aggravation of
asthma, even in neighborhoods where the primary ambient air quality standard was not
exceeded (13). Specific nitrate compounds such as peroxyacetyl nitrate are known to
be biologically reactive in atmospheres with concentrations of ozone, N02 and other
pollutants below the national primary standard. These considerations of the potential
biological effects of the atmospheric transformation products of N02 suggest that a
100 percent margin of safety below a moderately conservative estimate of the N0~
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—5—
effects-threshold is very desirable and defensible.
To achieve the above suggested maximum allowable exposure limits for short-
term N(>2 concentrations, we require an NOX emission standard for motor vehicles in
the range of 0.4 to 2.0 grains per mile (14). The precise NOX emission standard
required to assure that one-hour ambient concentrations do not exceed 375 to 630
ug/m^ (0.20 to 0.34 ppm) will be determined, in part, by the magnitude of NOX control
from stationary sources. However there is no reason to believe that an NOx emission
standard above 2.0 grams per mile will possibly achieve the above exposure limits (14)
In conclusion, based on my best judgment concerning the adverse human health
effects of short-term NOo exposures, I recommend a mobile source emission standard
for NOX in the range of 0.4 to 2.0 grams per mile.
Carl M. Shy, M.
February 3, 1975
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REFERENCES
1. Suzuki T and Ishikawa K. Research of effect of smog on human body. Research
and report on air pollution prevention, No 2, 199-221, 1965 (Quoted from Abe, M:
Effects of mixed N02 - S02 gas on human pulmonary functions: Effects of air
pollution on the human body. Bull of the Tokyo Med and Dent. Univ. 14:415-433,
1967).
2. von Nieding, G., H.M. Wagner, H. Krekeler, V. Smidt and K. Muysers.
Absorption of N02 in Low Concentrations in the Respiratory Tract and Its Acute
Clean Air Congress of the International Union of Air Pollution Prevention
Associations, Washington, D.C., December 6-11, 1970.
3. Rokaw, S.N., H.E. Swarm, Jr., R.L. Keenan, and J.R. Phillips. Human
Exposures to single pollutants: N02: in a controlled environment facility.
Presented at the Ninth Air Pollution Medical Research Conference, Denver,
Colorado, 24 July, 1968. (Unpublished)
4. Larsen, R.I. A Mathematical Model for Relating Air Quality Measurements
to Air Quality Standards. Environmental Protection Agency, Office of Air
Programs. Washington, D.C.: U.S. Government Printing Office, 1971. 56 pp.
5. Shy, C.M., J.P. Creason, M.E. Pearlman, K.E. McClain, F.B. Benson and M.M.
Young. The Chattanooga School Study: Effects of Community Exposure to Nitrogen
Dioxide. II. Incidence of Acute Respiratory Illness. J. Air Poll. Contr. Assoc.
^0(9):582-588, September 1970.
6. Shy, C.M. Human Health Consequences of Nitrogen Dioxide: A Review. In
Proceedings of the Conference on Health Effects of Air Pollutants. Assembly of
Life Sciences, National Academy of Sciences - National Research Council, October
3-5, 1973. Committee Print prepared for the Committee on Public Works, United
States Senate, November 1973, Serial No 93-15, pp. 363-405.
7. Pearlman, M.E., J.F. Finklea, J.P. Creason, C.M. Shy, M.M. Young and R.J.
Horton. Nitrogen Dioxide and Lower Respiratory Illness. Pediatrics 47(2);391-
398, February 1971.
8. Ehrlich, R. and M.C. Henry. Chronic Toxicity of Nitrogen Dioxide: I. Effects
on Resistance to Bacterial Pneumonia. Arch. Environ. Health l/7_: 860-865, 1968.
9. Ehrlich, R. Effect of Nitrogen Dioxide on Resistance to Respiratory
Infection. Bacteriol. Rev. _30:604-614, 1966.
10. Chen, C., T. Nakajima, and S. Kusumoto. On the chronic bronchitis of the
mice produced by exposure of 0.3-0.5 ppm N02 gas. J. Japan. Soc. Air Pollut.
7:194, 1972. (in Japanese)
11. Freeman, G., S.C. Crane, R.J. Stephens, and N.J. Furiosi. Environmental
factors in emphysema and a model system with N02. Yale J. Biol. Med. 40:566-575,
1968.
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12. Finklea, J.F. Conceptual basis for establishing standards. In Proceedings
of the Conference on Health Effects of Air Pollutants. Assembly of Life
Sciences, National Academy of Sciences - National Research Council, October 3-5,
1973. Committee Print prepared for the Committee on Public Works, United States
Senate, November 1973, Serial No 93-15, pp. 619-667.
13. Summary Report on Atmospheric Nitrates. U.S. Environmental Protection
Agency, National Environmental Research Center, Research Triangle Park, N.C.,
July 31, 1974.
14. Personal communication from John F. Finklea, Director, National Environmental
Research Center, Research Triangle Park, N.C., February, 1975.
-------
E. MR. LOUIS LOMBARDO
A CASE FOR AUTO EMISSION CONTROL
-------
Copies of this paper were unavailable for printing. Copies of the
transcript of this portion of the seminar are available for purchase from:
Ace-Federal Reporters, Inc.
415 2nd Street, N. E.
Washington, D. C. 20002
(202) 547-6222
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F. DR. BILLINGS BROWN
THE REDICULOUSNESS OF PRESENT
NOx STANDARDS
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THE RIDICULOUSNESS OF PRESENT NOx STANDARDS
Billings Brown,
SUMMARY
The available data on the ill effects of \0x have beer:
reviewed. There is little justification for any NOx air quality
or emission standards, and still less for the stringent standards
imposed by the Congress an^' supported by the EirA . The Direct cost
of this mistake is four billion Collars in excessive oil imports.
f-ome of the error could be rectified by relieving the starv^rds
an^ adjusting emission controls on post-1969 automobile engines
to save one million barrels per day in oil imports.
INTRODUCTION
Many volumes have been written on both sides of the fuel
economy versus automobile nitrogen oxides (NOx) emission contro-
versy since passage of the Clean Air Act and the peaking out of
domestic crude oil production, both of which occured in 1970.
Gasoline sufficiency and reduced NOx in urban areas will soon be
in titanic and mortal collision. I:intend to show that the too
stringent NOx air quality and automobile emission standards are
based upon flimsy data at best and fraudulent interpretation of
data at worst, politicians seeking to appease special interest
groups have evidently been duped by testimony of scientists
seeking to please their Federal funding agencies. I write as
one taxpayer who has examined the available literature on this
important subject.
HEALTH EFFECTS OF NOx
NTOx effects on health are presumed to be both direct, by
increased airway resistance or increased susceptibility to
infections; and indirect, by contributing to photochemical
smog.
Direct Effects
Even in the NOx capitol city (Los Angeles), concentrations
never exceed a few tenths part per million. California recom-
mended a one hour air quality standard of 0.25 ppm(l). Yet,prior
to 1969, no human health studies for NOx had been reported for
concentrations less than 1 ppm (2). To fill this gap, the EPA
-------
conducted a 6 month epidemiological study in Chattanooga,
Tennessee in 1963-9 (3,4). Because of proximity to a TNT
plant, NOx concentrations (6 month mean values) were higher
than in most U.S. cities and varied f rom Q.JO'43 ppm to 0.167
ppm (corrected values). Yet there was found to be no disc-
ernible difference (less than 1%) in forced expiratory volume
(a measure of airway resistance) between students living in
areas of highest and lowest NOx concentrations (Figure 4 of
Reference 3). The authors claimed a statistical difference,
but although statistics can sometimes hide results they cannot
produce a difference where none exists in the data. The authors
(4) also claimed an increase in respiratory disease in the
high NOx areas but this difference was slight (18%) and could
just as well be the result of the protocols of the study(7).
The EPA claims of health effects were questioned by
Eckardt (5). His valid misgivings were simply brushed aside in
Shy's response (6) without an answer. The validity of the study
was questioned Irter by Heuss (1) in a critical review. Heuss
correctly pointed out that "the NOx (air quality) standard is
based on (this) single epiderniological study by Shy". Their
questions were again brushed aside without answer, this time
by Earth (7).
NOx in Photochemical Smog
NOx is supposed to react with hydrocarbons to form photo-
chemical smog. This phenomenon is found only in Los Angeles. It
depends upon warm,stagnant,humid air; sunshine; and a very
crowde^ automobile population. These conditions are not duplic-
ated elsewhere in this country.
Most of the imagined evidence for blaming NOx for Los
Angeles smog is certainly due to Haagen-Smit, who while at
Cal Tech in 1951 incorrectly blamed XOx when he developed his
theory of photochemical smog (8). He later admitted " I had
guesse^ right....It (smog) wasn't my field...(9). But Haagen-
Smit soon mar'e smog chemistry not only his field but his life's
work. In 1955 he trie0' to support his guesses with experiments
(10). ris results were at first negative. Undaunted by facts, he
resorte^ to cheating (his verb) "to convince the politicians."(11).
To obtain positive results, he finally had to use conditions at
least 30 times worse than the worst Los Angeles smog (12). That
the atmospheric reactions between NOx and hydrocarbons cannot be
extrapolate^ to 1 pp:r. ;0x levels was not known to Haagen-bmit at
that time, but was well known to EPA in 1970 (13).
Haagen-.-jmt's success eventually brought him in 1969 to
national prominence as chairman of President Nixon's Task Force
on Pollution. Here he was in an excellent position to persuade
Senator KXiskie (oerhaos indirectly) to include NOx as a grievous
pollutant in his C,lean air act of 1970.
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CCNCLUSIONS
(1) Engine pollution controls reduce NCx emissions slightly
while reducing fuel economy considerable and increasing CC
emissions greatly.
(2) There is no evidence to support the conclusion that NOx
is dangerous to health.
(3) Relaxing NOx standards will save one million barrels of
gasoline per' day and four billion dollars per year in imports.
(4) Relaxing NOx standards will reduce CO emissions and thus
save lives.
^EFERENCEi-
1. J.M.Heuss.G.J.Nebel,J.M.Colucci, APCA Journal 21(9)535(1971)
2. P.K.Kueller, F.Hitchcock, AFCA Journal 19(9)670(1969)
3. C.F.Shy et al, APCA Journal 20(8)539(1970)
4. C.Mohy et al, APCA Journal 20(9)572(1970)
5. R.E.Eckardt, APCA Journal 20(12)832(1970)
6. C.F.Shy, APCA Journal 20(12)832(1970)
7. D.Jr, .Barth et al, APCA Journal 21(9)544(1971)
8. A .J.naagen-fimit, Ind .Eng.Chem. 44(6)1342(1952)
9. Christian Science Monitor, August 16,1973
10. A.J.Haagen-Smit,M.M.Fox, Ind.Eng.Chem.48(9)1484(1956)
11. A.J.Haagen-Smit,personal communication, February 20,1970
12. A .J .Kaapen-Smit.C .E.Bradley,Ind.Eng.Chem.45(9)2086(1953)
13. A .P.Altshuller.J.J.Bufalini,Environ.Sci.Tech. 5(1)39(1971),
14. W.A .Glasson,C .S .Tuesday,Environ.Sci.Tech.4(1)37(1970)
15. C.M.Shy, This Seminar, February 10,1975
16. T.R.Hauser,C.M.Shy,Environ.Sci.Tech.6(10)890(1972)
17. W.L.Faith, Chem.Eng.Prog. 62(10)41(1966)
18. W.L .Faith, Chem.Eng.News ,Dec.24,1973
19. National Academy of Sciences Report,Sept.1974,vol.3,p.126
20. Federal Register,June 5,1973,p.14762; cf various news
releases by Ruckleshaus and Fri, summer 1973
21. C.LaPointe,Automotive Eng.81(11)46(1973)
22. U.S.News and World Report,Jan.27,1975,p.61
23. EPA Environmental News,March 14,1974
24. R.Chaves,Automotive News,Feb.4,1974
25. Personal communication,Eric 0-Stork to Senator Moss,Nov.21,1974
26. Control Techniques for Carbon Monoxide....From Mobile Sources
27. Science,Sept. 1974
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Several times during 1973, the EPA admitted that "NOx is
not the widespread pollution problem once thought, and that a
90 percent cut in auto emissions of NOx from 1971 levels will
not be needed" (20). These pronouncements have not been
implemented by a relaxing of the standards.
THE COST
This NOx fraud is costing us four billion dollars per
year, and ranks with the biggest frauds of all time. Automobile
NOx emission standards requiring controls since 1969 result in
a miles-per-gallon loss on 1974 models of between 20 and 50
percent, EPA plaintive cries to the contrary (21). A 33 percent
reduction in fuel consumption by the existing post-1969 auto
fleet will save one million barrels per day of imported oil (22).
RELIEF IS AVAILABLE TODAY
The EPA has warned that tampering with pollution control
devices designed to reduce NOx might cause a loss in fuel
economy (23) and certainly would not give an increase. This
supposition is also false information, as a detailed study of
the EPA test methods and modification techniques will show (24).
These details were not presented in (23)t Evidently EPA zealots
rigger1 the tests to guarantee negative results. No conscientious
mechanic would have attempted to increase fuel ecomomy by using
the methods alleged by EPA.
I have personally adjusted dozens of engines using only a
screwdriver, always with a significant (usually 30 to 50 percent)
increase in fuel economy, even though Stork (25) says it is
unlikely. My own 1970 Valiant was improved from 13 to 18 miles
per gallon in city driving, and from 19 to 23 miles per gallon
in freeway driving. Recently I tampered with a neighbor's 1974
Maverick to increase its highway economy from 13 to 20 miles per
gallon. Any backyard mechanic can do what I have done to increase
mileagei advance vacuum ignition timing (by bypassing the heat
contjcolled valve), advance basic timing if required, lean the
catouretor idle mixture, and disable the exhaust gas recirculation
valve.
Eliminating the NOx controls will cause only a 6 percent
increase in NOx, but will result in up to a 90 percent decrease
in carbon monoxide (CO). The reason for this well known .opposite
behavior of the two pollutants is the inherent design of the
internal combustion enginei a lean air/fuel ratio burns the fuel
more completely (Decreases CO) but the higher temperature increas-.
formation of \Gx (26). This CO reduction will be welcomed by
residents OF many larpe cities, and will materially reduce the
4,000 Deaths per year attributed^ AS to auto emissions (27) which
should logically be attributed to the specific killer (CO).
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Nobody to my knowledge has given the slightest thought as
to whether Haggen-Smit might have been incorrect, guessed wrong
or was downright dishonest.
Glasson and Tuesday (14) reported smog experiments in
1969 that are contrary to Haagen-Hmit's results and instead
support Faith's calculations(lS).
NOx CONTROLS ARE TOO STRINGENT
Shy (15) defended a mobile source emission standard "in
the range of 0.4 to 2.0 grams per mile." However, he based his
defense solely on his own 1969 Chattanooga studies (3,4). Shy
failed to mention his later correction paper (16) which-. ' shows
that the NOx concentration at School 1 (which had heavily
influenced his conclusions) was in error by 35 percent.
If meaningfully cleaner £ir had beenachieved through NOx
emission reductions, perhaps the price paid would not have been
too much,, but there has been only microscopic redeeming social
value obtained. Larry Faith, an engineer who has been active in
Los Angeles pollution control for over 20 years, has said con-
sistently that NOx control cannot be justified (17),and that
removing all NOx emission controls would increase the number of
smoggy days in the Los Angeles air basin only from 210 to 225
per year (18). Los Angeles is the only location that might
possibly have an NOx problem.
The National Academy of Sciences (NAS) study £19) concluded
that "the current Federal statutory NOx automobile emission
standard of 0.4 grams per mile may be somewhat stringent for
meeting the the Federal ambient air quality standard for NOx in
Los Angeles....The existing analyses relating NOx emissions to
subsequent oxidant formation are considered inadequate. It is
not certain, based on available evidence, that the Federal ambient
air qualitystandard for oxidant of 0.08 ppm would be met in all
large cities.... if the.... emission standard of 0.4 g/mi were
relaxed."
The first NAS conclusion certainly is justified, as the
emission standard of 0.4 g/mi represents an accumulated margin
of safety of over 500 percent even when based on Shy's Chattanooga
results (which give an'" additional margin of safety) .
The second NAS conclusion is concerned with the statutory
air quality standard for oxidant, as there is no evidence at all
that photochemical smog exists in any city other than Los Angeles,
hence there is no evidence that anybody's health has been or will
be degraded except possibly in Los Angeles.
My own conclusion, strengthened after conversations with
several EPA officials, is that there is no justification for any
NOx air quality standard. The Chattanooga study was^merely
window dressing to ijustify a Congressional blunder in the Clean
Air Act of 1970.
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G. DR. HAROLD MCFARLAND
HEALTH EFFECTS OF NO2 & NO2 IN COMBINATION
WITH OTHER POLLUTANTS
-------
HEALTH EFFECTS OF NO2 AND NO2 IN COMBINATION WITH OTHER POLLUTANTS
* H. N. MacFarland
** N. K. Weaver
*** W. M. Busey
Presented at the Scientific Seminar on Automotive Pollutants,
Washington, D. C. February 10-12, 1975
Present Addresses:
Director of Toxicology, Medical Department, Gulf Oil
Corporation, Pittsburgh, Pa. 15Z30
Director, Division of Medicine and Biological Science,
American Petroleum Institute, Washington, D. C. 20006
* * * Pathologist, Experimental Pathology Laboratories, Inc.
Herndon, Va. 22070
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IEALTH EFFECTS OF NO2 AND NOZ IN COMBINATION WITH OTHER POLLUTANTS
H. N. MacFarland, N. K. Weaver and W. M. Busey
Design of Investigation
The studies to be described in this paper were under-
taken to determine whether or not synergistic effects between certain
common air pollutants could be detected in primates under conditions
of chronic exposure. The investigations have been previously reported
in abstract form in Ann. intern. Med. 74, 840 (1971); the full report
is in preparation. The pollutants examined included three gases,
sulfur dioxide, nitrogen dioxide and carbon monoxide, and two solids
disseminated as aerosols, calcium sulfate and lead chlorobromide.
These materials and the concentrations employed are shown in Slide 1.
Not only were the effects of these five agents determined
singly, but also the gas-gas and gas-particulate mixtures received
examination.
The species selected was the cynamolgus monkey
(Macaca fascicularis); juvenile animals weighing 2. 5 - 3. 5 kg. were
employed. Twenty groups, each consisting of 9 monkeys, were assigned
at random to 20 exposure chambers. There was one control group and
19 exposed groups. The complement in each chamber consisted of 5
males and 4 females, or vice versa. The animals were housed in
individual cages and disposed in a 3 x 3 array in a single layer in the
chambers.
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AGENTS EXAMINED AND CONCENTRATIONS USED
Sulfur dioxide
Nitrogen dioxide
Carbon monoxide
Calcium sulfate
Lead chlorobromide
SO2
N02
CO
CaSO4
PbClBr
0. 5 & 10. 0 ppm
0. 5 & 7. 5 ppm
20. 0 & 67. 5 ppm
10 mg/m3
(MMD = 1. 84/«)
0. 6 mg/m3
(MMD = 0.98/0
SLIDE 1
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-2-
The chambers were of stainless steel and glass con-
struction and had a volume of about 6. 5 cu. m. They were operated
dynamically at a flow rate slightly over 1 cu. m. /min. Agents were
introduced into the inlet pipe, just upstream from its point of entry
at the top of the chamber. Sampling probes used to obtain samples
of the atmospheres for analysis were located above the layer of
animals.
All animals used in the study were subjected to a
rigorous screening procedure before acceptance. The tests employed
were derived from a more comprehensive battery of tests utilized in
the scheduled examination of the animals throughout the course of the
study. These procedures are listed on the following slides (Slides 2-6).
Animals accepted for study were placed in the exposure
chambers for a pre-exposure period of 10 weeks. They breathed a
carefully purified and conditioned air which was the basic air supply
to the chambers. For the first 2 weeks, no tests were performed; the
animals were allowed to become acclimated to the chamber situation.
This was followed by a 8-week period in which some 5 sets of determina-
tions of base-line values for all parameters were conducted.
At this point, exposure to the selected agent or combina-
tion of agents commenced. The animals were exposed around-the-clock,
24 hours per day, except for two quarter-hour periods daily when the
chambers were cleaned and the food supply replenished. Drinking water
was available at all times in the chambers. Exposures were carried on
-------
HEMATOLOGICAL DETERMINATIONS
Variable Abbreviations Units of Measurement
Hematocrit Hct. %
Hemoglobin Hgb. gm. %
Total erythrocyte counts RBC xl06/cmm
Total leukocyte counts WBC xl03/cmm
SLIDE 2
-------
SERUM BIOCHEMICAL DETERMINATIONS
Variable
Blood glucose
Serum albumin
Serum sodium
Serum calcium
transaminase
Serum glutamic-pyruvic
transaminase
Serum lactic acid
dehydrogenase
Abbreviations
se Glu.
litrogen BUN
i bilirubin
i protein
nin
isium K
im Na
•ides Cl
3n dioxide CO2
um Ca
mic-oxaloacetic SCOT
Units of Measurement
mg. %
mg. %
mg. %
gm. %
gm. %
mEq/1
mEq/1
mEq/1
mEq/1
mg. %
K units
SGPT
LDH
Serum alkaline phosphatase ALK. PO4
RF units
WROB units
K. A. units
SLIDE 3
-------
PULMONARY FUNCTION MEASUREMENTS
Mechanical Properties of the Lung and Respiratory System
Variable
Abbreviation
Units of Measuremei
Respiratory System Flow Resistance
During Inspiration
Respiratory System Flow Resistance
During Expiration
Tidal Volume
Respiratory Rate
Dynamic Compliance of the Lung
Pulmonary Flow Resistance
Work of Breathing During Inspiration
per ml. Tidal Volume
Work of Breathing During Expiration
per ml. Tidal Volume
cm. H2 O/ml/sec
cm. H2O/ml/sec
ml.
breaths/minute
ml/cm. H2O
cm. H2O/ml./sec
gm. cm. /ml Vrp
W(e)/ml VT gm. cm./ml VT
Rrs (i)
Rrs (e)
VT
RR
Cdyn(l)
Rl
SLIDE 4
-------
PULMONARY FUNCTION MEASUREMENTS
Diffusion
Variable
Diffusing Capacity of the Lung
for Carbon Monoxide
Abbreviation
DL
CO
Units of Measurement
ml/min/mm. Hg. STPD
Distribution of Inspired Air, Nitrogen Washout
Variable
Number of Breaths from 80% to
1% Nitrogen
Time from 80% to 1% Nitrogen
Cumulative Tidal Volume from
80% to 1% Nitrogen
Respiratory Rate
Tidal Volume
Abbreviation
N(l% N2)
t (1% N2)
CVT(1% N2)
RR
T
Units of Measurement
Number
Seconds
liters STPD
Breaths/minute
ml. BTPS
SLIDE 5
-------
OTHER TEST PROCEDURES
Arterial Blood Gas and pH
Variable
Arterial Blood Oxygen Tension
Arterial Blood Carbon Dioxide
Arterial Blood Acidity
Abbreviation
P
aco.
Units of Measurement
mm. Hg.
mm. Hg.
Units
Variable
Red Cell Fragility
Blood Lead
Delta-Aminolevulinic Acid
Urinary coproporphyrins
Carboxyhemoglobin
Special Tests
Abbreviation
Blood Pb
£-ALA
Units of Measurement
% NaCl Concentration
of lead/100 ml of
blood
mg/100 ml. of urine
mg/ml/24 hr. total
urine
HbCO
Weights
Growth weights; Terminal body weights;
Organ weights; Organ/body weight ratios.
SLIDE 6
-------
-3-
7 days a week for a duration of 104 weeks (2 years). At termination,
the monkeys were sacrificed, gross necropsies performed, and
tissues taken for histopathological evaluation (Slide 7).
Results
We may begin our review of the results of the study
by eliminating from consideration seven of the agents and agent com-
binations where no statistically significant effects on any of the 40-odd
parameters listed on previous slides were detected. These negative
results are shown on Slide 8.
Next, there were four agents or agent combinations
which affected only one parameter and these are shown on Slide 9.
Thus, we are left with eight agent and agent combinations
where unequivocally significant changes in the values of some parameters
were detected.
Four of these groups were exposed to atmospheres
containing, as at least one of the constituents, nitrogen dioxide at 7. 5 ppm.
These four groups are shown on Slide 10. There were a series of altera-
tions, common to all these four groups, shown on Slide 11 . These changes
are indicative of a deterioration in the distribution of ventilation.
Pathological changes in the lungs were found in the animals from each
of these four groups exposed to the high concentration of NO2. These
changes consisted of hyperplasia and hypertrophy of epithelial cells in the
-------
HISTOPATHOLOGICAL STUDIES
Tissues from the following organs were examined microscopically:
Trachea
Lung
Peribronchial lymph node
Heart
Liver
Kidney
SLIDE 7
-------
GENT AND AGENT COMBINATIONS WHICH PRODUCED NO DETECTABLE EFFECTS
NO2 0. 5 ppm
SO2 0. 5 ppm and 10. 0 ppm
CO 20. 0 ppm
CaSO4 10. 0 mg/m3
NO2 0. 5 ppm
SO2 10. 0 ppm
SO2 10. 0 ppm
CaSO4 10. 0 mg/m
SLIDE 8
-------
/AGENTS AND AGENT COMBINATIONS WHICH PRODUCED ONLY A SINGLE EFFECT
CO 67. 5 ppm
NO2
CO
SO2
CO
SO2
CO
0. 5 ppm
67. 5 ppm,
0. 5 ppm
67. 5 ppm
10. 0 ppm
20. 0 ppm
elevated HbCO
elevated HbCO
elevated HbCO
increased red cell
fragility
SLIDE 9
-------
GROUPS EXPOSED TO NITROGEN DIOXIDE AT 7. 5 PPM
IN WHICH EFFECTS WERE SEEN
NO2 7. 5 ppm
NO2
CaSO4 10. 0 ppm
7. 5 ppm j
10. 0 ppm J
NO2 7. 5 ppm
CO 20. 0 ppm
NO2 7. 5 ppm
SO2 0. 5 ppm
SLIDE 10
-------
CHANGES SEEN IN ALL GROUPS EXPOSED TO NITROGEN DIOXIDE AT 7. 5 PPM
(WITH OR WITHOUT A SECOND CONSTITUENT)
Respiratory rate RR increased
Breaths to 1% N2 N (1% N2) increased
Cumulative tidal CV (1% N2) increased
volume to 1% N2
SLIDE 11
-------
-4-
respiratory bronchioles with thickening of the walls of the respiratory
bronchioles.
There were also some isolated changes noted in the
NO2 at 7. 5 ppm groups. For instance, a compensated acidosis was
observed in the group exposed only to NO2 at 7. 5 ppm. The arterial
oxygen tension was depressed and there was an elevated arterial carbon
dioxide tension and increase in plasma bicarbonate. It was detected
only during the first six weeks of exposure and then returned to normal.
This group exhibited an increase in red cell fragility, and this change
was also detected in the combination group exposed to NO2 at 7. 5 ppm with
CO at 20, 0 ppm.
There are only four groups left to examine, and in all
of these, lead chlorobromide at 0. 6 mg/m3 was at least one of the
constituents (Slide 12). In the groups exposed to lead chlorobromide
alone and in combination with either the low level of NO2 or the high
level of CO, a deterioration in the distribution of ventilation was seen,
similar to that previously described for groups exposed to the high level
of NO2 (Slide 13). This adverse effect, however, was not detected in the
group which received the lead compound in combination with SO2 at
10. 0 ppm.
All four lead groups exhibited pathological changes in
the kidney. These changes consisted of a slight dilation of the proximal
convoluted tubules with degeneration of the epithelial cells of the
proximal convoluted tubules, characterized by cytoplasmic vacuolation
and nuclear vesiculation. The presence of numerous eosinophilic,
-------
GROUPS EXPOSED TO LEAD CHLOROBROMIDE AT 0. 6 MG/M3
IN WHICH EFFECTS WERE SEEN
PbClBr
PbClBr
N02
PbClBr
S02
PbClBr
CO
0. 6 mg/m3
0. 6 mg/m3
0. 5 ppm
0. 6 mg/m3
10. 0 ppm
0. 6 mg/m3
67. 5 ppm
SLIDE 12
-------
CHANGES SEEN IN GROUPS EXPOSED TO LEAD CHLOROBROMIDE ALONE AND IN
COMBINATION WITH NITROGEN DIOXIDE OR CARBON MONOXIDE
Respiratory Rate RR increased
Breaths to 1% N2 N (1% N2) increased
Cumulative tidal CVT (1%N2) increased
volume to 1% N2
Note: These changes not seen in group exposed to PbClBr
with SO2 at 10. 0 ppm.
SLIDE 13
-------
a cid-fast, intranuclear inclusion bodies was also noted. In addition,
red cell fragility was decreased and increases in blood lead level,
and in urinary d-ALA and coproporphyrin were seen in all groups.
Summary
Cynamolgus monkeys were exposed essentially continuously
for two years to a number of common air pollutants, alone and in combina-
tion. Two main sets of groups showed unequivocal, significant changes.
Animals receiving NO2 at 7. 5 ppm exhibited a deterioration in the dis-
tribution of ventilation, and pathological changes in the respiratory
bronchioles were noted. Animals exposed to lead chlorobromide also
showed a deterioration in the distribution of ventilation, and pathological
changes in the proximal convuluted tubules of the kidney were seen.
No synergistic effects were detected in the animals
exposed to a combination of agents. However, evidence of an antagonistic
effect in monkeys exposed to lead chlorobromide at 0. 6 mg/m3 with
sulfur dioxide at 10. 0 ppm. was obtained.
Acknowledgement
This investigation was supported by the Coordinating
Research Council and conducted at Hazleton Laboratories, Inc.
-------
H. DR RICHARD EHRLICH
INTERACTION BETWEEN NO2 EXPOSURE &
RESPIRATORY INFECTION
-------
Interaction Between NG>2 Exposure and Respiratory Infection
Richard Ehrlich, PhD
Life Sciences Research Division
IIT Research Institute
Chicago, 111 60616
Gaseous pollutants exert their effect by contact with the
membraneous surfaces of the body. Such surfaces are particularly
sensitive to injury and at the same time possess high absorptive
capacity. The severity of the damage is related to the
concentration of the pollutant, duration or frequency of exposure,
and to the physicochemical properties of the pollutant, as for
example its solubility. The effects of pollutants on surfaces
of the respiratory tract are of special importance in relation
to respiratory infections. An irritant gas reaching the epithelium
of the trachea or the bronchi can paralyze the cilia, alter the
flow and the consistency of mucus, or reduce the phagocytic
activity of alveolar macrophages. All of these functions,
individually or in combination, constitute the major defense
mechanisms against respiratory infections.
Indeed, there is sufficient experimental evidence that air
pollutants interfere with the elimination of inhaled bacteria from
the respiratory tract and increase the host's susceptibility to
bacterial invasion. More specifically, experimental studies
strongly support the existence of causal relationship between
exposure to nitrogen dioxide and reduced resistance to respiratory
infections caused by inhalation of airborne pathogenic bacteria
and viruses.
-------
I would like to take a few minutes now to summarize and
bring up to date some of the experimental evidence gathered over
the years in our laboratories.
Basically, two experimental procedures were used as shown
in the FIRST SLIDE (SLIDE 1) . To elucidate the predisposing effects
of nitrogen dioxide on the resistance to infection the animals were
exposed first to nitrogen dioxide and at various time intervals
thereafter, challenged with aerosol of the infectious microorganisms.
To determine the effects of nitrogen dioxide on an existing
infection the experimental sequence was simply reversed. The
bacterial agents used were Klebsiella pneumoniae and Streptococcus
pyogenes. K. pneumoniae is normally found in the nose and mouth
of healthy individuals and is present as a secondary invader in
the lungs of patients with chronic pulmonary disease. Pneumonia
caused by this bacterium is characterized by the production of
thick gelatinous sputum and frequently leads to lung abscesses.
The nasopharynx and the skin of man are the normal habitats
of the beta-hemolytic Streptococcus. The common acute illnesses
that are the immediate consequences of active streptococcal
infections include pharyngitis and tonsilitis. Less frequently
septic complications such as pneumona can occur from direct extension
(3
from a pharynaal focus.
-------
The changes in resistance to infection were usually based
on three parameters:
one - increased mortality rates
two - reduced survival times
three - reduced capacity to clear inhaled viable bacteria
from the lungs.
However, many additional parameters were, measured during the
various studies including histopathological examination of the
respiratory tract tissues, humor.il- (antibody) and cell-mediated
i
immunity and several physiological functions. The changes in
i-TRTnuno logical response observed in our laboratories during exposures
to NO 7 will be discussed by Dr, Fenters in the following paper,
The data presented here are primarily reported as excess
mortalities in experimental animals exposed to nitrogen dioxide
and the infectious agent over those observed in control animcls
challenged with the infectious agent but not exposed to nitrogen
dioxide. It is of importance to note that throughout the
experiments there were essentially no deaths which could be
ascribed to nitrogen dioxide exposure per se.
In acute studies, summarized in the NEXT SLIDE (SLIDE 2),
mice were exposed for 2 hr to N0? in concentrations ranging from
1.5 to 25 ppm (2.8 to 47.0 ing/m ) then challenged with bacterial
aerosol 1, 6, and 27 hr later. The minimum N02 concentration
required to produce a statistically significant rise in mortality
-------
H
m
m
CD
m
H
m
m
o
i
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m x
-D
sS
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H
O
0
ro
I
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MORTALITY CHANGE , %
oo
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-------
•t
was 3.5 p --. : (6,0 •. ;-/«! ''; ',>;.<-,i. ihe "L Ifc'-ti >e"-> chall-n^e tool< place
w> thin 1 hr a ft or .h. f e~ ^ •.,•>• '"' ~r, >~ NO,-, r •«-•omtre, When the
eballerge W3"> j, _ •, ^ , . i^-. ' i': -. • >n' ;>:•. c-'; r^ >x ta'j i-"Ico w;-oc noted
at 6 br, but no*- C-C '11 \\c., at. NO., r.onr 3rd ra': '.ons of 5 ppm (9.4 jug/m"'
NEXT SMr/E (SL1 ",-;•, 3} ?u:'iran -,CP L-IL. acute exposure (\ita for
three specif'3 o" la'-1. -.:•- t~,'- y ;- uraaJ s , na.nely. mice, hamstevs „ and
sciuirrel :uor.',.';'ys , ^o- >:'''.11 ..^..'."its , the da'.H J'EIOW t:he ac-".na\
mortality rates among aii^rlL crialleiiged with the infecti .us ag^nc
not exposed r.c 1*40.
exposed to coocentrauiorri of Ii00 which did net affecc the
ruorrs L:. tj, ra;-_s. .-'.rid
exposed ti':> N0? ^o.ir..-:-:ii;ra: ion- vhich eanaaoe^ the -B jvt jl\ ti js .
The deat'i rates aioc-ng co'.ii.vo'i. anluial;-; reflect tha nature] re-.;is "ance
of each species to the infectious s^ani. Tha liig;-.--ir levels •> f NO,,
required to Irtfec1; -airisterc an" squ IT :el n.onktys .'re prinarllj' clue
to the high resj-fHaa^e cf tl^cc. a:iLTii;..la to ur-tctvri3l pneuino/.xa,
rather then to basic differr.ice In the action of rhe poll at ant on
the bacterial defense rriec'ia^ LTK . Indeed, thii resp-rctive death
rates in mice, hairst,?r3 ard jnonlcey? not exposed to NO^ were 41,
11, and 07^ while at ere pr.n t Lime i he estinated .". ahalecl dose was
1000 bacteria for mice but rior^ than 100,000 bacteria for hamsters
and monkeys.
-------
100
90
80
O 60
50
40
30
20
10
Significant Excess Mortality
( ) Number of Animals
Mice Hamsters
(1080)
(550)
(530)
1.5 3.5
to to
2.5 25
18211
13771
5 35
to to
25 65
Squirrel
Monkey
I (IS)
(3)
5
to
35
50
N02 Concentration Range,ppm
EFFECTS OF 2-HR ACUTE EXPOSURE
TO N02 AND CHALLENGE WITH _K_ PNEUMONIAE
ON MORTALITY OF MICE, HAMSTERS,
AND SQUIRREL MONKEYS
-------
The NEXT SLIDE (SLIDE 4) summarizes very preliminary results
of experiments currently being conducted in our laboratories. The
main objective is to determine the effects of combination of
pollutants, and of repeated short-term exposures to those pollutants
on resistance to respiratory infections. The slide shows the
excess mortalities in mice after exposure to nitrogen dioxide, ozone,
and combination of the two pollutants. As expected increased
mortalities were observed upon single exposure to 5.0 and 3.5 ppm
NC>2 and 0.5 and 0.1 ppm of ozone. What is really interesting, are
the higher mortalities seen upon- exposure to combination of the two
pollutants, and more so the enhanced mortalities upon exposure
to the combination of 2.0 ppm N0« and 0,05 ppm ozone,, As I have
mentioned before these are preliminary data and replicate studies
are underway to establish the statistical significance of this
observation.
In chronic studies, summarized in the NEXT SLIDE (SLIDE 5)
•a
mice were exposed to 0.5 ppm (0.94 mg/m ) N02 for 24 hours a day,
7 days a week for up to 12 months. Challenge with the infectious
agent took place after 1, 3, 6, 9 and 12 months of exposure.
Significant increases in mortality were seen after a continuous
NOp exposure for 3 months or longer. Additional groups of mice,
not shown in the slide, were also exposure for up to 12 months
to the same N0? concentrations for 6 and 18 hours a day. Increased
mortalities were observed after 6 and 9 months exposure, but not
after 12 months.
-------
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EXCESS MORTALITY %
o
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-------
50
SS
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(/)
-------
Upon continuous exposure to 1.5 ppm (2.8 mg/m )
significant increases in mortalities were observed already after
an 8 hr exposure and persisted for up to 90 days (the excess
mortality for 8 hr exposure should be 24%).
More limited chronic studies were conducted with squirrel
monkeys exposed to 5 ppm N0« for 2 months and to 10 ppm NO^ for
1 month and then challenged with the infectious agent by
intratracheal route. Deaths did not occur among nine monkeys
used as controls. However, two out of seven (2870) and one out
of four (257») died in the 5 and 10 ppm N02 exposure groups,
respectively.
Parallel to enhanced mortalities a decrease in mean survival
time was seen in all animals. Also the rate of clearance of viable
bacteria from lungs of mice, hamsters, and monkeys was reduced upon
exposure to NCU. The next slide provides an example of the effects
of N02 on lung clearance in mice (SLIDE 6). In control animals
not exposed to N0«, the numbers of viable bacteria decreased
markedly during first 6 hours following the infectious challenge.
Thereafter, the numbers increased, reflecting growth of the
bacteria, reaching the initial concentration after approximately
7 to 8 hours. In mice exposed to N02 the initial clearance period
was reduced to less then 5 hours, and the original concentration
of bacteria was re-established in less then 7 hours. The lung
-------
clearance rate was similarily affected by long-terra exposures
to 0.5 ppm N02> Mice exposed to NO,, for 24 hr a day showed
significantly reduced capacity to clear viable bacteria after
6 months of exposure, while those exposed to N09 for 6 or 18 hr
a day after 9 months.
Autopsies of mice that died during the acute studies
showed high incidence of purulent exudate in the pleural cavities.
Lungs of mice exposed to 3.5 ppm N02 and higher showed varied
degrees of congestion and dilation of veins and capillaries.
Histopathological examination of lungs of mice exposed to 0.5 ppm
disclosed various degrees of inflammation of the bronchioles and
surface erosion of the epithelium. The alveoli were expended in
all mice exposed to N02 for 3 months or longer. A marked increase
in alveolar area was noticed, primarily related to alveolar
expension rather than septal breakage. The overall lesions appeared
to be consistent with the microscopic development of early focal
emphysema.
Studies of health effects of air pollution have traditionally
been concerned with causal association between a single pollutant
'and disease state. However, since it is well established that
multiple factors are frequently responsible for the occurrence of
natural diseases it is important to consider multiple causality
-------
in evaluation of the biological effects of pollutants. One form
of interaction is depicted by the infectivity model system which
reflects the enhancement of bacterial or viral infections by
exposure to air pollutants.
Utilizing this model system striking differences in
bacterial and, to a lesser degree, viral pneumonias were observed
in conjunction with short-term as well as long term exposures to
NC>2 levels near those found in polluted urban areas. This effect
of N02 in rendering the animal host less capable of dealing with
inhaled infectious microorganisms is a biological impairment
observed in a number of animal species including mice, hamsters,
and non-human primates. The action of N02 appears to be mediated
through alterations of specific defense mechanisms including the
macrophage system, anatomical structure of lungs, and humoral
immunity.
The infective model system appears to mimic a situation that
is likely to occur in man. The necessary components for its
spontaneous occurrence in man are exposure to a sufficiently high
concentration of NC^ and presence of infectious microorganisms
capable to invade and colonize in the human host, exploiting the
state of reduced resistance.
8
-------
Studies on interaction between NO,, and respiratory
infections provided appreciable amounts of data applicable and
utilized in the establishment of N0« air quality criteria.
Nevertheless additional effort must be directed toward the
clarficiation of several parameters governing this causal
relationship. These include comparisons of the relative importance
of ciliary, phagocytic, humoral and cellular defense mechanisms,
and determination of reversibility of the observed effects. Most
important, however, appear to be studies directed toward the
elucidation of effects of exposures to combinations of pollutants
on the resistance to respiratory infection. Although additional
experimental as well as epidemiological data are needed, the
information available to date does not justify any relaxation
of the primary air quality standards for nitrogen dioxide of
'3
100 yg/m (0.05 ppm) for an annual average.
-------
I. DR. DONALD GARDNER
TIME/DOSE RESPONSE FOR NO2 EXPOSURE IN
AN INFECTIVITY MODEL SYSTEM
-------
TIME/DOSE RESPONSE FOR NITROGEN DIOXIDE
EXPOSURE IN AN INFECTIVITY MODEL SYSTEM
by
D. E. Gardner, Ph.D.
Environmental Protection Agency
National Environmental Research Center
Research Triangle Park, North Carolina 27711 U.S.A.
-------
TIME/DOSE RESPONSE FOR NITROGEN DIOXIDE EXPOSURE
IN AN INFECTIVITY MODEL SYSTEM
Introduction
A number of atmospheric chemicals are characterized by very uneven
concentrations from day to day or even hour by hour, by the rate of their
production and meteorological influences. This is particularly amplified in
the case of chemicals formed secondarily through interactions occurring in the
atmosphere. For instance, the level of atmospheric N02 is governed not only
by the rate of production of NO, but also by factors favoring its conversion
to N02 existing independently in the environment. This generally results in a
low basal atmospheric concentration on which are superimposed higher peaks
usually of very short duration and irregular occurrence. Thus, it is of great
value to determine the relative importance of the more uniform low basal concen-
tration (as might be modeled from a weekly, monthly or yearly average) in
comparison to the high, short peaks. Furthermore, it is of importance to know
what biological interactions may occur in both systems if applied in the same
regimen of exposure.
Due to the ambiguities in the literature concerning dose-response for N02,
more definitive work remains to be done to determine the relative importance
of various dose regimens and the possible influence of "threshold," tolerance,
healing, and adaptation in biological reactions to NOp. Because of the interest
in dose-response and the possibility that several mechanisms might be operating
concurrently in NOo toxicity, the following studies were to be undertaken:
[Slide 1]
1. Acute exposure versus the same C x T over a longer period,
2. Continuous dose versus the intermittent application,
-------
EXPOSURE REGIMENS ... .
SHORT-TERM EXPOSURES - USING A CONSTANT
CONCENTRATION x TIMES (C X T) DOSE OF 7.
CONTINUOUS EXPOSURES - KEEP CONCENTRATION
FIXED BUT VARY THE LENGTH OF EXPOSURE.
INTERMITTENT EXPOSURES - FIXED CONCENTRATION
BUT INTERRUPTED EXPOSURES FOR GIVEN TIME.
SPIKE EXPOSURES - SUPERIMPOSITION OF SPIKES
ON A LOW-BASAL DOSE.
-------
3. Super-imposition of spike on a low basal dose versus continuous
and intermittent at a single concentration.
Preliminary data from some of these experiments will be presented here.
[Slide off]
The model that we have employed in this work primarily involves resistance
to the induction of bacterial pneumonia. This parameter was selected
because of its demonstrated effects at ambient concentrations of air
pollutants. This model also probably reflects a summation of the total
toxic assaults on the deep lung such as edema, inflammation, cellular
Q
necrosis, reduced macrophage function, and upper airway effects. [Slide 2]
Briefly, this model consists of the superimposition of a pathogenic bacterial
aerosol (Streptococcus pyogenes, Group C, isolated from a pharyngeal abscess
of a guinea pig) following exposure to the gaseous toxicant. Control
animals receive bacteria aerosol only. [Slide 3]
This system has been efficiently utilized in environmental toxicologic
911 10 12
studies ozone, ' nitrogen dioxide, irradiated auto smog, trace metals,
13 14
such as NiO, MnC^, This model has been successfully employed to
enhance the pulmonary infectivity in mice, »'1«''j»'4 rats, hamsters,
and squirrel monkeys. Among the infectious agents eliciting this
reaction in the above animals are:
-------
~»..
" ' INFECT! VITY MO DEL -
SPECIES POLLUTANTS MICROORGANISM
MICE ' OZONE STREPTOCOCCUS
RATS NITROGEN DIOXIDE KLEBSIELLA
| . HAMSTERS AUTO SMOG (IRRAD.) DIPLOCOCCUS
i
I
I • SQUIRREL MONKEYS TRACE METALS INFLUENZA
-------
Streptococcus pyogenes , Klebsiolla pneumoni ae , Di p_l ococcus
pneumonlae and influenza PR-8 virus. Thus, this model is an
exquisitely sensitive indicator of biological effects in v _iv o .
In addition, the model is useful in studying the mechanism of
action of the pollutants.17'18
Results
In answer to the question raised in the introduction, the
following results have been obtained:
[Slide 4]
1. Dose response studies were conducted utilizing a CxT of
7. This CT was chosen based on the published threshold for NO^
using the infectivity model which was (3.5 ppm x two hours).
This slide shows the enhancement of mortality from pulmonary infection
resulting from the same CxT exposure to N02 over different time
periods. It will be noted that the actual concentration exerted
more influence than the duration of exposure. If no interaction
occurred between concentration and time, (that is, if they had equal
importance), all the test groups could be expected to have a 15%
higher mortality than controls. However, as the data indicate,
there was a gradient response from a high mortality enhancement of
approximately 50% to a low which equalled controls. [Slide 5]
The interaction of a constant concentration with time over a
longer period was also examined. It is the over-all plan to construct
a family of curves at various concentrations ranging from 0.5 ppm
to 14 ppm. At the present moment, three concentrations of N02
have been studied. A level of 3.5 ppm was used for comparison with
the study mentioned above. A lower value of 0.5 ppm was selected
-------
i
m
9 K
S '
-*-
-a-
V JUnvlUOW Ml 30N3M3 JJIfl *
1 '
e
«^ kv
Q.K JS
L^^
S
O
-------
<„
PERCENT MORTALITY OF MICE VERSUS THE LENGTH OF CONTINUOUS EXPOSURE
TO VARIOUS PPM OF NO] PRIOR TO CHALLENGE WITH STREPTOCOCCI
TIME
-------
s i IK. o this concentration r t'pr<".,onted tin* lowest iiquro in
literature yielding positive results for chronic exposine in I In-
infective system. Preliminary data using 1.5 ppm of Nu~ are
also included. The data shown in this slide represent 60 individual
observations for the 3.5 ppm level, eight for the 0.5 ppm, and six
for the 1.5 ppm level. The simple linear regression for the 3.5 pr-.>i
and 0.5 ppm of NO,, shows that the mortality increased with time and
concentration and was statistically significant at the 0.01 pro-
bability level. Predictions which can be generated from these
regressions with respect to the true average differences in mortality
show that statistical significant change from controls (P\'. 05) occur
after one hour exposure to 3.5 ppm, and after three weeks of exposure
to 0.5 ppm N0?. However, the regression for 1,5 ppm was significant
only at the 0.25 probability level and is represented by a dashed
line. Additional data is now being collected in order to better
define the 1.5 ppm response curve. While it was noted in the
first series of experiments that I discussed that there was a
strong interaction in favor of concentration over time, this latter
study still illustrates the importance of obtaining toxicological
information from long-term exposures to NOp. [Slide offj
Using this same model system (fixed concentration versus
time), other concentrations are now being tested for the purpose of
developing information which can be used to develop regression
curves at other concentrations which then can be used for pre-
dicting purposes.
The data from the 3.5 ppm series of experiments which were
just shown were also analyzed in order to determine the influences
of exposure time on the mean survival period of the exposed animals
-------
s
as calculated according to the equation shown on the next slide (6)
MST = <(AxB)
n
Where "A" is the last dny on which any individual mouse was alive,
"B" is the number of mice surviving "A" days; "D" is the last day
of the experiment (in this case 15); "L" is the number of mice
which were alive on day "D"; and "n" is the initial number of
mice in the experimental group. [Slide 7]
A statistically significant (p<.05) regression with a negative
slope was observed for mean survival of mice challenged with
Streptococci pyogenes versus length of exposure to 3.5 ppm for
various periods prior to the challenge. It is evident that there
is an inverse relationship between survival and length of exposure.
With this parameter, after 1 or 2 hours of exposure to 3.5 ppm,
one may be 95% confident that the NOp exposed mice, on the average,
lived between 18 and 36 hours less than do control mice.
The next slide (8) presents preliminary data from experiments
which were designed to test the effect of concentration and time
as above, but utilizing an intermittent exposure model in place
of continuous. In these experiments animals were exposed for 7 hr/
days, 7 days/week to 3.5 ppm N02. At various times animals were
removed and given the bacterial aerosol. This slide illustrates
that N02 shows a significant increasing linear relationship with
duration of exposure. (Preliminary) [Slide off]
Conclusion
I would like to point out that the data presented show that:
1- In short-term exposure to N02, the concentration employed
has a much greater influence than duration of exposure in terms of
th<\ r.'"H!H' CxT.
-------
KEAN SURVIVAL TI'.'C or HCC FOLI.OV'IMS CHftl.LEKRE TO
VERSUS LENGTH OF Ut GlUrfL' 10 3.5 ppm NO? tf.l CHL CHALLENGE
1 10
EXPOSURE TIME IN HOURS TO 3. 5 ppm NO;
100
JOO
Figure 3
-------
PERCENT MORTAIITY OF MICE VERSUS THE LENGTH OF EITHER CONTINUOUS OR INTERMITTENT EXPOSURE
TO 35 PPM N02 PRIOR TO CHALLENGE WITH STREPTOCOCCI
M
10
7D
i
_ o
SYMIOL EXPOSURE GROUP
O CONTINUOUS
O INTERMITTENT (7 hn/diyl
• ' 3< 5S 79 103 127
151 175
TIME
199 223 247 271
y
295 311
343
-------
PERCENT MORTALITY OF MICE FROM BACTERIAL PNEUMONIA
FOLLOWING CONTINUOUS AND INTERMITTENT EXPOSURE TO 3.5 ppm N02 VERSUS C X T
10
10
~ T0
o
I 60
S
I 40
s-
g
» 20
10
PERCENT MORTALITY O
••U + 27.1logio(CT) >1_J
SYMBOL METHOD OF OBTAINING CT
O CONTINUOUS EXPOSURE TO 3.5 ppm NO?
O EXPOSURE TO 3.5 ppm NOj 7hn/diy
10 20 40 SO 80 100
CONCENTRATION X TIME
200
400
-------
suggested to explain the enhancement of pulmonary infectivily
following long term or repeated exposures:
1. Other damages which are known to occur in the lung, that
is, various anatomic and chemical alterations might have an influence
on the role of the infection, and that these lesions might increase
22 23
with time. '
2. That there is an effect on the alveolar macrophage prior
to their emergence into the lung which could be mediated through
? A p c o c
free radicals, nitroxides, or peroxides. ''
3. A combination of the above two responses could also
contribute to the alteration of the host's natural defenses against
the inhaled microorganism.
These mechanisms will have to be tested through specific
experiments designed to uncover the mode of action of N0?. An
amplification of the toxic effects of NO,, may be examined through
a combination of acute, chronic and intermittent N02 exposures
similar to the ones discussed in this manuscript,
-------
RHFIiRKNCHS
1. CUI.Y, ii. l.cB., PATTON, F. M., GOLDBERG, S. U . and KOPLAN, I:.:
ToxJcity of l he oxide of nitrogen.
AMA Arch. Ind. Hyg. Occup. Mod. j_0, 423-425, 1054
2. '1','AGK'JiR, IV. P., DUNCAN, B. ' IT. , WRIGHT, P. G. and STO'KINt.nK; II.L.V
Expcriincni.nl study of threshold limit .of NO^. ''
Arch. Env. Illth. \Q_ 455-466, 1965 "'• • .
3. JUNE, C. 11., CAVALLI, R.' D. and K'RIGHT, R. R..: .
Unpublished results cited by Stok-inger and Coffin in A_i_r
Pol Jut 3..on, 2nd Edition, Stern, A. C. (Editor) Academic Press,
•'" ••'•'New-York, 1968 / pp\446*5"46. •' ''."•
4. BOREN, H. G. •'•• ' • ' .. "...
• •.'Carbon • as a.--carrier' mechanrs-m fo:r. irritant -gases. '. '-. .-.'-.•
Arch. Env. Hlth. 8^, 119, 1964
5. FREEMAN, G., STEPHENS, R. J., CRANE, S. C. and FURI OS I, N. J.:
The subacute nitrogen dioxide-induced lesion of the rat lung.
Arch. Env. Hlth. 1_8_, 609-612, 1969
6. KLEINERMAN, J. and t'.'RIGHT, G. W.
The effects of prolonged and repeated nitrogen dioxide inhala-
tion on the lungs of rabbits and guinea p5gs.
Presented at 5th Annual Air Pollution Medical Research Confer.
Ca, State Dept. of Public Hlth., Los Angeles, Ca. Dec. 1961
7. EHRLICH, R. and HENRY, M. C.
• Chronic -toxicity of nitrogen dioxide I effects on resistance
•to bacterial pneumonia.
Arch. Eny- Hlth. 17 , 860-865, 1968" .. .
8. EHRLICH, R., SILVERSTEIN, E., MAIGETTER, R. Z., FENTERS, J. D.
and GARDNER, D. E. :
Immunologic response in vaccinated mice during long-term
exposure to nitrogen dioxide.
Submitted to Env. Res., 1974
^>
"•VN '
9. COFFIN, D. L. and GARDNER, D. E.: ' '
Interaction of biological agents and chemical air pollutants.
Ann. Occup. Hyg. 15 , 219-234, 1972.
10. EHRLICI1, R. :
Effects of nitrogen dioxide on resistance to respiratory
infection.
Bact. Rev. 3^,604-614, 1966
11. COFFIN, D. L., HLOMMHR, R. J., GARDNER, D. E. and IIOI.ZMAN, R.S.; '
Effect of air pollution on a ] t e ra t. j on of susceptibility to
pii]i:.on;iry infection. i'roc L-C d i n;;f. M' 3rd Annual Conference
on AlMor.phcrj c Contamination in Confined Space.
Aerospace Medical Research Laboratory. 71-f,0, 1068
-------
12. COFFIN, 1). I. .'Mid r.LOMMIIR, K . J . :
Acute toxicily of ir radi ;i t c'i auto c,\h;'ust. Its indication
by enhancement of mortaJJty from .'> I JH ptococc.a ] pneumonia,
. Arch. Env. illth. JUS, 36-57, ]J)67
13. PORT, C. '!).', PUNTERS,' J. 1). / BURL 1 CM , R., COFFIN, 1), L.''.'
-.. and CAKIhVHR,.:;T): !>S', 'J . and EIIRLICH ,' 'R . :""
Jjffcct of manganese dioxJde on resistance to respiratory
. • .infections . •
• '''Abs.' Am.' Soc'.''of "Microbiology, Chica p,o / "-'II, -1974 ' ••'• • •'*
15. BLOMMER, E. J. :' . •
(Unpublished data)
.16. HENRY, M. C. , EHRL.1CH, R. and BLAIR, W. H.; "
Effect of nitrogen dioxide on resistance of squirrel
monkeys to K. pn.eumoniae infection.
Arch. Env. Hlth. 18_ t 580-587, 1969
17. COFFIN, D. L., GARDNER, D. E. and HOLZMAN, R, S.;
.Influence of ozone on pulmonary cells.
Arch. Env. Hlth. 1^^633-636, 1968
18. GARDNER, D. E., HOLZMAN, R, S. and COFFIN, D. L,;
•Effects of nitrogen dioxide on pulmonary cell population.
. J, of Bact. 98 t 1041-1043, 1969
19. GARDNER, D. E., PFITZER, E. A., CHRISTIAN, R. T., and
COFFIN, D. L, :
.Loss of protective factor for alveolar macrophages when
exposed to ozone.
Arch. Int. Med. 127. 1078-1084, 1971
20. GREEN, G.v M. and KASS, E. H.:
The role of the alveolar macrophage in the clearance of
bacteria from the lung.
J. Exp. Med. 119 f 167-176, 1964
21. GODLESKI. J. J. and BRAIN, J. D.:
The origin of alveolar macrophage in mouse radiation
Chimeras, J. Exp. Med. 136 (3) 630-643, 1972.
~" - ~* I
22. FREEMAN, C,., JUHOS, L. T., FURIOSI, N. J., MUSSENDEN, R.,
STEIMITN'S, R. J. and EVANS, M. J.:
PalJiol oj:y of i'ul I'jon.i ry Ijjscasc from l.xposurc to Ambient C:;.--. o:
(Nitrogen Dioxide and Ozone)
Arch. Environ. Ulth, 29, 203-210,' 1974
-------
...; • r r nc c s
>.>. IUJI-L, G. C., TOKIKA, Y,, MUr.LLHK, P. K.: '
I.unp, coJlap.cn and clastin d cna tura t j on i_n v i v_o follovii;};.
inhalation of NO,,. Air Pollution Control Assn. Mcclinj',
Son l-'rn nc i sco , June 1966.
AI'CA .Paper //66-7
24. STOKINGr.R, ll. I;. ami COFFIN, D. L.:
•' Biological cffecit of'air p.ol 1 uta.'nt s • i n Mr j^l l:.uti o,n • ,• •>... y' .;•
2nd Editi'on, Stern,.-.A. C.,' (lulitor) Acadoiiic Press, N':'. ' Y'7 '" '-
1968,' pp 446-546
25.. MENZEL, 1). B., R012J1M/J. N. and Ll-C, S. D.:
" "^'Vitamin P..:. Th-c-. .b i/Ql.ogioa^.-.and en.va ronracnta 1 -an.itioxidant
Agr. and Food Ch'em. 20, 481-486, 1972 ' '
26, CHOW,, C.. K.' and'TAPPEL, A. L,:
An enzymatic protective mechanism against lipid perox'J elation
damage to lung of ozone exposed rats.
Lipids, 7_, 518-524 , ;1972
-------
J. DR. JAMES FENTERS
IMMUNOLOGIC RESPONSE DURING EXPOSURE
TO NO2
-------
IMMUNOLOGIC RESPONSE DURING
EXPOSURE TO NITROGEN DIOXIDE
J. Fenters
IIT Research Institute
10 West 35th Street
Chicago, Illinois 60616
Presented: February 10, 1975
Scientific Seminar on Automotive Pollutants, Washington, D.C.
Studies which Dr. Ehrlich just reported showed that low levels
of N0? in conjunction with a challenge by respiratory agents such
as Klebsiella pneumoniae or influenza virus can enhance mortality
rates in either mice or squirrel monkeys. The specific mechanisms
by which an air pollutant affects the infectious process have
been questioned. Suppressions or inhibition of phagocytosis and
v
production of interferon are two possible mechanisms by which N02
exacerbates respiratory disease; however, until recently there
had been no thorough investigation of the immune response of
animals continuously exposed to nitrogen dioxide. The purpose
of this report is to present data on this particular subject.
In the first two series of studies, squirrel monkeys served as
the experimental host and influenza A/PR/8 virus was the infectious
agent. One of the reasons influenza virus was chosen was that
-------
it can be tested for with ease by many serological and immuno-
logical techniques. SLIDE 1. Seven male squirrel monkeys were
given serial intratracheal injection of 0.2 to 0.5 ml of mouse-
adapted influenza virus, with the first injection given 24 hr
before the initiation of exposure to N02- Thereafter, the animals
were exposed continuously to 5 ppm of N02 for the duration of the
study, a duration of 137 days. During N02 exposure, monkeys were
again challenged with virus on days 37 and 77, and bled one week
after the challenges. Otherwise, blood samples were taken bi-
weekly. The hemagglutination-inhibition (or HI) and serum neutrali-
zing (or SN) antibody tests were performed using the microtiter
technique for HI test and embryonated chicken eggs for the SN test.
In all monkeys, HI antibody appeared much sooner than the SN anti-
body but the titers were not affected by exposure to N02- On the
other hand, the production of SN antibody appeared to be influenced
by N09 exposure, as shown in this slide. After the second challenge
with influenza virus, the anamnestic response was significantly
higher in the control animals. A similar pattern was also noted
-------
600
500
400
300
200
100
N02
a-—a Air
" Infectious Challenge
/\
\
r
__J
\
•
\
0
20
40
60 80 100 120 140
Exposure Days
Fig.I MEAN RECIPROCAL SN ANTIBODY TITERS OF SQUIRREL
MONKEYS EXPOSED TO 5ppm (9400/iq/m3) OF N02AND
CHALLENGED WITH MOUSE ADAPTED A/PR-8 INFLUENZA VIRUS
-------
after the third virus challenge. However, at the termination
of the experiment after 4.5 months exposure to N02, the differences
in SN antibody levels in the two groups of monkeys were no longer
significant.
In the second study SLIDE 2 the effect of a 16-month continuous
exposure to 1 ppm of N02 in the immune response of squirrel monkeys
to influenza infection was examined. Eight male monkeys were challenge
five times with a monkey-adap ted influenza A/PR/8 virus. The first
four challenges, given 24 hours before initiation of NOj atmosphere,
were by intratracheal injections. The fifth, given after 266 days,
was by respiratory challenge with airborne influenza virus. The
animals' antigenic responses were again measured by HI and SN anti-
body levels at various time intervals.
The data indicate that exposure to NC^ again influenced the forma-
tion of protective SN antibody. Monkeys exposed to NC^ produced
SN antibody within 21 days after virus infection, whereas only one
monkey exposed to air showed comparable response. Throughout the
-------
o>
400
300
200
100
• • N02
°—° Air
Infectious Challenge
0
50
100
150 200 250
N02 Exposure, Days
300
350
40
FIG. 2 \ ME AN RECIPROCAL SN ANTIBODY TITERS OF SQUIRREL MONKEYS EXPOSED TO
Ippm (I880/,tq/m3) OF N02AND CHALLENGED WITH MONKEY ADAPTED A/PR-8
INFLUENZA VIRUS
-------
12-month exposure, monkeys exposed to N02 consistently showed
higher SN antibody titers than those exposed to air. SLIDE OFF.
These two studies show that the effects of N02 on the immunological
response of the monkey appears to be in part related to the ability
of the virus to multiply in the lung tissue of the experimental
host, as well as the natural resistance of the host to the
infectious agent. Using mouse-adapted influenza virus, as shown in
the first slide,the ability to form serum neutralization antibody
appeared to be depressed in monkeys exposed to 5 ppm NO,,. On the
other hand, upon challenge with the monkey-adapted influenza virus
\.
the serum neutralizing antibody appeared sooner and at significantly
higher levels in monkeys exposed to 1 ppm of N02. Thus in this
case, the N02 exposure appeared to enhance the establishment and
multiplication of the monkey-adapted virus. It was obvious in
both studies that exposure to N02 altered the immunological response
in the experimental host, squirrel monkeys.
The relative small numbers of monkeys used in these experi-
ments precluded definitive conclusions to be drawn as to the effects
-------
of low concentrations of NC^ on the immune response to influenza.
Therefore, another study was initiated in which the mouse was the
experimental animal model system. This allowed us to use larger
groups of experimental animals, and we were able to evaluate not
only the HI and SN antibody response, but also serum immunoglobulin
levels.
Immunoglobulins are defined by the World Health Organization
as "proteins of animal origin endowed with known antibody activity,
and certain proteins related to them by chemical structure and
hence antigen specificity." Immunoglobulins are found in serum,
urine, spinal fluid, milk, saliva, tears, lymph nodes and spleen,
and are produced by plasma cells and lymphocytes at various stages
of differentiation. One of the major developments in an understand-
ing of the humoral immune response was this recognition of the major
classes of immunoglobulin molecules that differ in chemical structure
and biologic function. One of the major changes that occurs in the
early antibody response is the type of antibody molecule present.
-------
The first antibody to appear in the serum of an animal after stimu-
lation with a protein antigen is IgM, but this is usually supple-
mented by IgG antibody during the early stages of the response.
Subsequent development of simple quantitative methods has
\
permitted characterization of immunoglobulin patterns in various
clinical settings as well as in population studies. For example,
increased serum IgA levels with normal IgM and IgG was observed by
Biegel and Krumholz (1968) in adults with chronic obstructive
pulmonary emphysema. Roberts (1973), when studying farmer's lung
disease patients, found mean IgA and IgG levels to be significantly
higher than those of normal individuals. However, in these studies,
it is yet to be determined whether the changes in immunoglobulin
levels represent cause or effect. More important to our program,
Kosmider (1973) has reported that occupational exposure of workers to
0.5 to 2.7 ppm N02 for 6 to 8 hours per day for up to 6 years resulted
in elevated levels of serum IgA and IgM and decreases in IgG anti-
body. Thus it was of interest to study immunoglobulin levels in
-------
experimental animals since changes in concentration of serum
immunoglobulins in man have been reported in studies of several
chronic lung disorders.
The following study was devised to determine the effect of long-
term exposure to low concentrations of N02 on the immunological
response of mice vaccinated with a highly purified influenza virus
vaccine. Four-week-old specific-pathogen-free male Swiss albino
mice CD-I strain were quarantined for 2 weeks prior to initiation of
the study. The influenza vaccine used was the Zonomune chick embryo
A2/Taiwan/I/64, administered in the dofsal thoracic area by a single
subcutaneous injection of 0.1 ml containing approximately 280 CCA
units. To determine immunoglobulin concentration, quantitative
radial immunodiffusion plates for mouse immunoglobulins IgA, IgM,
IgG, and IgG£ were obtained connercially. Reference standards ob-
tained from pooled sera of normal mice were assayed daily, in dupli-
cate, to provide quality control. In addition, mouse immunoglobulin
-------
standards from a commercial source were assayed concurrently to
quantitate the experimental samples. For the assays, duplicate
serum samples were used from each of the 7 to 10 serum samples,
with each sample representing the pooled sera of two mice.
The experimental protocol is shown in SLIDE 3. Prior to
vaccination groups of mice were exposed continuously for 12 weeks
to one of three environmental conditions:
• filtered air or 0 ppm of N02
• 2 ppm of N02
• 0.5 ppm of N02 with daily 1-hr peaks of 2 ppm of N0?,
5 days/week - the peaking concentration
After the 3-month exposure, all mice were vaccinated by a single
subcutaneous injection with the influenza vaccine and thereafter
held in either NO 2 environment or filtered air. As*a result, we
had 7 experimental groups. That is,after vaccination the group of
mice held in filtered air were placed in either 2 ppm N02, peaking
N02, or filtered air; mice held in 2 ppm N02 were placed in filtered
air or back into the 2 ppm N02 atmosphere; and mice held in
8
-------
EXPOSURE, WEEKS
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40
Air Air
y '
Air NV2
Air . N02~0.5/2
PPm Air
ppm
T
N02-0.5/2 Air
N02-0.5/2 • N02-0.5/2
y
Vaccination
Bleeding
EXPERIMENTAL PROTOCOL
Figure 3
-------
peaking NO^ were also placed in filtered air or their respective
atmosphere. Using these groups we would be able to determine both
the preimmunization and post immunization effects of N0«. Groups
of 14 to 20 mice were killed 2, 4, 8, 12, 16, 20, 24 and 28 weeks
after the vaccination and sera were assayed for HI and SN antibodies
and the four classes of iimnunoglobulins.
SLIDE 4
These data show the effect of continuous exposure, both before
and after vaccination, on the SN response. Peak antibody titers
were delayed somewhat in the experimental mice and titers were
markedly depressed in mice exposed to N0« 2 weeks after vaccination.
A significant, four-fold SN titer depression was seen in mice con-
tinuously exposed to 0.5/2 ppm of NC^, with a mean titer of <1:8
as compared to the mean SN titer of 1:34 in control mice. Thereafter,
the titers were similar throughout the study.
SLIDE 5
The data here show the effect of NC^ on the immune response when
the NO,, exposure comes immediately after antigenic stimulation
-------
-------
0)
4-
H
c
o
-Q
10 —
N02 Exposure
Pre-Vacc Post-Vacc
o— _
0
0
0
0
0.5/2
2
4
Weeks
6 8
After Vaccination
Figure 5
10
12
-------
As seen previously, the immediate effect is obvious. Two weeks
after vaccination, the SN titers are significantly depressed in
mice exposed to either 2 ppm N02 or the peaking concentrations of
N02 The mean titer of the control mice was 1:34, compared to
1:8 in the experimental mice. Again, the maximum titers in those
mice exposed to 0.5/2 ppm N0? occurred 2 weeks after the controls
and those exposed to 2 ppm were maximum 8 weeks after vaccination.
With the exception of the 2 week sample, the differences in titers
throughout the study were not significant.
\
SLIDE 6
These data indicate the effect of NC^ on the immune response
prior to antigenic stimulation. Two weeks after vaccination,
antibody titers in both N02 groups were depressed, with those mice
exposed for 3 months to 0.5/2 ppm N02 exhibiting a significantly
depressed SN level. This group exhibited a consistently lowered
immune response. As in the other groups there was a delay in the
peak SN antibody titer in mice held in 2 ppm NC^.
SLIDE OFF
10
-------
50 r—
40
o>
4—
o
JQ
30 —
< 20 —
10 -
N02 Exposure
Pre-Vacc Post-Vacc
0
0.5/2
2
0
0
0
•—a
468
• Weeks After Vaccination
Figure 6
-------
The SN seroconversion rates further confirmed the effect of
N02 during the 2 week post-vaccination period. The seroconversion
rate was 10070 in vaccinated mice exposed to air, 070 in mice con-
tinuously exposed to 0.5/2 ppm N02 and ranged from 40 to 57% in
the remaining N0« exposure groups.
The HI antibody levels were determined throughout the study
and, as has been the case in the previous studies, there was little
difference between control and experimental animals. The HI anti-
body declined at a similar rate in all animals. These data are
comparable to those described in which squirrel monkeys were exposed
to 5 ppm of N0£ and infected with a mouse-adapted, or non-replicating,
strain of influenza A/PR/8 virus. Thus, in both species exposure to
NC>2 appeared to-depress SN antibody formation after challenge with
a nonreplicating viral antigen.
The effect of NO^ on immunoglobulin levels in mice was
observed over three time intervals; the 12-week period before
vaccination; the 2-week period immediately following the vaccination;
11
-------
and the 28-week period following the vaccination. Thus, the effect
of NC>2 on the immune response was determined in the absence of
antigenic stimuli, immediately after introduction of the antigen,
and over a longer period of time after the vaccination.
Actual concentrations of immunoglobulins, expressed in mg/ml
of serum, in nonvaccinated mice exposed for 12 weeks to NC^ are
shown in SLIDE 7. Mice exposed to N02 showed a significant decrease
in serum IgA and increase in IgG, levels relative to control mice
\
exposed to air. The concentrations of serum IgM and IgG2 were also
higher in mice held in the NC^ environments, but the statistical
significance of the differences could be ascertained only for
those exposed to 0.5/2 ppm NC^.
The following three slides show the changes in percent con-
centration of serum immunoglobulins during the 12-week pre-vaccina-
tion period and the 2-week period immediately following vaccination.
The values shown for each immunoglobulin are the percent of total
immunoglobulins determined at each sampling period.
12
-------
SLIDE 8
The percent serum IgM was fairly stable during the 12 weeks
exposure to air and remained at approximately the same level during
the 2-week exposure to air after the vaccination. However, when
mice were exposed to N02 after the vaccination a 55% decrease in
per cent serum IgM was seen. A very similar decrease in serum
IgM was observed during the 12-week pre-vaccination exposure to either
peaking 0.5/2 or 2 ppm NQ«. However, when mice exposed to N02 were
transferred to filtered air after vaccination, the percent serum
IgM increased, reaching a level similar to that of control mice
never exposed to NC^.
SLIDE 9
The percent concentration of serum IgA in mice exposed to air
was essentially unchanged during the 12-week prevaccination period,
and a small increase was seen after the vaccination. When these
mice were exposed to NC^ for 2 weeks after vaccination, a 40 to 5070
decrease in serum IgA was recorded. The 12-week-long
13
-------
exposure to either 0.5/2 or 2 ppm N02 resulted in a 50% reduction
in serum IgA concentration which remained at the reduced level
after vaccination. Upon transfer to filtered air after vaccination,
a marked increase in percent serum IgA, approximately to the level
of mice held in filtered air before vaccination, was seen.
SLIDE 10
The percent serum IgG, or IgG2 concentrations did not change
markedly during the 12-week exposure to filtered air. After
vaccination a slight decrease in IgG^ and an increase in IgG2
was noticed in mice exposed to air. Exposure of these mice to
N0~ during the 2 weeks after vaccination resulted in a 47
to 57% elevation of IgG^ At the same time, IgG2 showed a 15 to
207o decrease. Exposure to N02 before vaccination resulted in a
singificant increase in percent serum IgG^ and decrease in serum
IgG9 . These changes continued during the 2-week post-vaccination
exposure to NG>2 . When mice exposed to 0.5/2 ppm N02 were removed
from the N02 environment and held in filtered air after the
vaccination, a reversal in this trend was observed: The
14
-------
SERUM IMMUNOGLOBULIN CONCENTRATIONS IN NONVACCINATED MICE
AFTER 12 WEEKS EXPOSURE TO NITROGEN DIOXIDE
N02
Exposure
0
0.5/2
2
Immunoglobulin (rag/ml)
IRA
0.71
0.56+
0.46+
IgM
0.22
0.28*
0.23
IgGl
2.65
s.oot
3.70t
IRG7
4.30
5.30*
4.72
Significant (P ^5%) increase or decrease from
filtered air control.
Figure 7
15
-------
N02 Exposure, PPM
0.5/2
Vaccination
V)
c
"3
X)
o>
O»
O
§ 4
E
E 3
I 2-
V)
C
0)
O
k.
Q>
a.
I -
4 8 12 13 14
IgM
I i
4 8 12 13 14
4 8 12 13 14
Duration Of Exposure, Weeks
Figure 8
-------
Exposure, PPM
— 0
- 0.5/2
— 2
Vaccination
CO
I "1
o
§ 9H
£
.i SH
I 7H
l_
(/) 6 ~
c 5-
" 4
o
Q_
«
IgA
8 12 13 14
4 8 12 13 14
4 8 12 13 14
Duration Of Exposure , Weeks
Figure 9
-------
N02 Exposure, PPM
- 0
-0.5/2
-2
Vaccination
4 8 12 13 14
4 8 12 13 14
Duration Of Exposure , Weeks
Figure 10
igG,
4 8 12 13 14
-------
decreased whereas IgG2 increased to a level equivalent to that
of mice exposed continuously to air.
SLIDE OFF - LIGHTS
The third phase of the immunoglobulin program was directed
toward evaluating the effect of NC^ on immunoglobulins during the
28-week period following vaccination. Direct assessment of NC^
effects on the actual concentrations of immunoglobulins over the
28-week exposure period following the vaccination was difficult,
inasmuch as their levels are partly related to age (Rector, 1973).
Therefore, a two-way analysis of variance was used whereby the age
factor was removed as a source of variation. A multiple-range
test was applied to the age adjusted immunoglobulin values to
establish the ranking and significance of the differences between
the various exposure groups.
The 28-week-long exposure to NC^ after the vaccination did not
influence the concentration of serum IgA with the exception of mice
15
-------
maintained in filtered air for 12 weeks before the vaccination and
exposed to 0.5/2 ppm N0« after the vaccination. These animals showed
a significant increase in this immunoglobulin. Concentrations of
serum IgM in all mice exposed to NC^ were elevated when compared
with the control mice. Serum IgG, and IgG« showed a similar pattern;
elevation of these immunoglobulins was seen in all mice exposed
to N02>
In summary, in both animal model systems the immune response
was affected by N0« exposure. When using a replicating virus system,
increased SN response was found,perhaps indicating increased sus-
ceptibility to the virus. In a non-replicating system, the SN
response was depressed. After 12 weeks exposure to N02 and prior
to vaccination, IgA levels were depressed and IgM and IgG were in-
creased. During the 2-week period immediately following vaccination,
exposure to NC^ appeared to be the major factor influencing the
percent concentration of serum immunoglobulins. During the 28-week-
long exposure to NC^ after vaccination, the serum IgM and IgG were
elevated.
16
-------
REFERENCES
Beigel, A.A. , and Krumholz, R.A. (1968). An immunoglobulin
abnormality in pulmonary emphysema. Am. Rev. Resp. Dis. 97,
217-222.
Roberts, R.C., Wenzel, F.J., and Emanuel, D.A. (1973).
Serum immunoglobulin levels in farmer's lung disease.
J. Allerg. Clin. Immunol. 52, 297r302.
Kosmider, S. , Misiewicz, A., Felus, E., Drozdz, M., and
Ludyga, K. (1973). Experimentelle und Klinische Untersuch-
ungen uber den Einfluss der Stickstoffoxyde auf die
Immunitat. Int. Arch. Arbeitsmed. 31, 9-23.
-------
K. DR. JEAN FRENCH
RECENT EPIDEMIOLOGIC STUDIES WITH RESPECT
TO NITROGEN OXIDE
-------
RECENT EPIDEMIOLOGIC STUDIES ON HEALTH EFFECTS
RELATED TO EXPOSURE TO NOV
Presented at Scientific Seminar on Automotive Pollutants
Thomas Jefferson Auditorium
U.S. Department of Agriculture
South Building, 14th and Independence Avenue
Washington, D.C.
February 11, 1975
Jean G. French, Dr.P.H.
-------
Although the health intelligence base for adverse human health
effects from NCL was limited at the time the national ambient air quality
standard was set, subsequent studies support the initial findings that
long term exposures and repeated short term exposures to elevated levels
of nitrogen dioxide can increase susceptibility to acute respiratory
illness and increase the risk of chronic lung disease. There is also
reason to suspect that other oxides of nitrogen including nitrous acid,
nitric acid and suspended particulate nitrates will adversely effect
health.
3
The existing annual NCL standard of 100 ug/m was based primarily
123
on the Chattanooga School Children studies ' ' conducted from November
1968 through April 1969. In this study long term exposure to ambient N02
concentrations between 117 and 205 ug/m (0.062 and 0.109 ppm) accompanied
by suspended nitrate concentrations between 4 and 6 ug/m for six months
•
and longer was associated with an 18.8% excess in acute respiratory
illness in families, significantly decreased lung function (FEVQ 75) in
elementary school females and signfiicantly increased bronchitis morbidity
in elementary school children exposed for two and three years.
Estimates of community exposure to N0~ in the initial Chattanooga
study were derived from air monitoring data obtained with gas bubblers,
employing the 24 hour Jacobs-Hochheiser method. Since the time of the
study, the Jacobs-Hochheiser method has been proven unreliable and this
information created the need to re-evaluate the relationship between a
quantitative exposure level and observed adverse health effects in
Chattanooga using data obtained with alternate methods of monitoring.
-------
Exposure estimates were derived from the network air monitoring stations
established by the Division of Abatement, National Air Pollution Control
Administration in the Chattanooga, Tennessee--Rossville, Georgia area.
Continuous recordings of NCL utilizing colorimetric Saltzman technique
were taken at ten stations from December 1967 through November 1968. The
constancy of nitrogen dioxide emissions, the topographical features of
the area and the similarity of wind patterns allowed estimation of the
Saltzman data to Chattanooga CHESS communities.
In the original Chattanooga health studies the sampling for NO,,
using the Jacobs-Hochheiser method limited the presentation of data to
daily or annual average N0? concentrations where as the continuous
Saltzman N0~ method used by the Division of Abatement provided additional
4
information on-hourly and daily frequency distributions of N02 concentrations.
The high frequency of inversions, light winds, local topography and
<
the point source of nitrogen dioxide emissions together contributed to
an exposure pattern near the TNT plant consisting of peak nitrogen
dioxide concentrations at ground level for 3 to 4 hours daily on 60
percent of the days, or approximately 10 percent of the hours through
most of the year. Therefore, the 90th percentile of the*frequency
distribution observed for hourly concentrations measured by the Saltzman
method was selected as a more appropriate estimate of NO,, exposure to be
related to the observed adverse health effect. An excess of acute
respiratory illness among females was. consistently observed when the
o
90th percentile of hourly NO,, concentrations was 376 ug/m (.20 ppm) or
above. When similar exposures were 188 to 282 ug/m3 (0.10 to 0.15 ppm)
the evidence was not consistent. On the study of bronchitis rates
-------
in children, those exposed for two to three years to peak MO, concentrations
t_
of 188 to 282 ug/m (0.10 to 0.15 ppm) had significantly higher bronchitis
rates than sick children in the lowest exposure neighborhood.3
Since the initial CHESS study in Chattanooga, a vigorous pollution
control program instituted by the Department of Defense and a decrease
in TNT production has been accompanied by a decrease in NQ2 emissions as
evidenced by a decrease in the annual average levels of N02 in the most
exposed study neighborhoods. Despite these lower annual N02 levels, the
population living in the community with the previously high annual average
exposure to N02 continued to experience intermittent short term exposure to
N02 as measured by the 90th percent!le of daily hourly N02 concentrations.
This set of.circumstances provided the opportunity to assess whether
or not individuals experiencing a decrease in annual average exposure to
t
N02 levels but still exposed to intermittent high levels of N02 would
continue to experience significant adverse health effects.
Subsequent CHESS studies were conducted in Chattanooga encompassing
the period from 1968 to 1973. Unfortunately the Jacobs-Hochheiser method
of measuring N02 was used in these studies from 1968 to 1972 when the
chemiluminescent method was introduced thus necessitating the substitution
of continuous Saltzman data for the year 1968 and additional Saltzman
data for specific stations in 1970 and 1971 (Table 1). The estimated
average annual pollutant exposure Levels in the three study areas in
Chattanooga from 1968 through 1972 are shown in Table 1. The annual
average levels of N02 in the most exposed study neighborhoods dropped
from ug/m3 in 1968 to 56 ug/m3 in 1973. The 90th percentile of
daily nitrogen dioxide concentrations shown in Table 2 ranged from 76 to
220 ug/m3 in 1972 and 66 to 133 ug/m3 in 1973 and the hourly values
-------
TABLE 1
Estimated Average Annual Pollutant Exposure Levels
in Three Study Areas in Chattanooga, Tennessee, 1968-1972
Pollutant
Nitrogen3
Dioxide
Suspended
Nitrates
Suspended
Sul fates
Total
Suspended ,
Parti culates
Sector and
Exposure Ranking*
I- Low
I I- Intermediate
Ill-High
I -Low
1 1- Intermediate
I II- High
I -Low
I I- Intermediate
Ill-High
I -Low;
I I- Intermediate
Ill-High
Estimated
Average Annual -
Concentrations, us/m
1968-69+
56*
113*
150-395*
2
3
6
12
10
10
62
72
81
1970
45**
45**
48*
1
2
3
13
13
13
64
63
51
1971
45**
45**
56*
2
3
6
10
10
10
64
62
52
1972
43a
49a
56a
__
--
__
.._
68
62
51
National
Air Quality
Primary Standard
Annual Average
100 ug/m3
None
None
75 ug/m3
*NCL Data - Saltzman Colorimetric Method
**Estimated from trend observed in high exposure area
Chemiluminescence Method
Geometric Mean
-------
Daily Nitrogen Dioxide Concentrations Observed at Chattanooga Air Monitoring Station^*3/>>.'/ /
t"/> *
<. >O ..
Communi ty
Exposure
High
Intermed-
iate
Low
NAPCA Abatement
•Station Number
19
15
17" •
20
161
CHESS
Station Number
31
32
33
34
21
1,
22
41
Daily NO? Values ^VJC*
Year
. 1968
1972**
1973
1968
1970
1971
1972**
1973
1968
1970
1971
1972**
1973
1968
1972**
1973
1968
1972**
1973
1968
1972**
• 1973
1968
1972**
1973
Annual
Average
395
91
60
150
41
57
46
44
188'
55
54
49
39
282
37
31
i*n
41
41
—
56
63
43
57
90th
Percent! le
921
220
118
282
68 •
91
75
64
48?
95
94
76
63
677
76
55
320
64
62
— ,
78
89
62
84
99th
Percentile
1466
333
185
526
120 ' -
147
104
106
Maxinftjm
1880
359
263
327
123
155
136
164
959 ' ! • 120-J
200 : 236
150 : 163
107 i 114
122 176
i
1166 1711
136 ! 178
77 ; 90
714
82
86
_
111
112
75
' 110
752
91
91
—
142
122
76
120
1968, 1970 and 1971 concentrations measured by Saltzman method.
chemiluminescence method.
1972 and 1973 concentrations measured by
-------
o
ranged from 81 to 256 ug/m as shown in Table 3. The 90th percentile
maximum hourly N02 values ranged from 228 to 815 ug/m in 1972. (Table
4). In 1968 and in 1971, the neighborhoods closest to the plant also had
exposure to relatively high levels of suspended nitrates (5.06.0 ug/m3).
In the intermediate exposure community annual average N0? levels also
fell from 113 ug/m in 1968 to 49 ug/m3 in 1973. Short term exposures
in this community were decreased from formerly high levels but still
maximum hourly values of about 116 to 164 ug/m were noted on 36 days
each year. In the low exposure area, annual average N0? exposures were
o
also reduced from 56 down to 43 ug/m . Peak hourly exposures on all but
a few days were like those of the intermediate exposure community.
Prevalence of Chronic Respiratory Symptoms in Chattanooga 1971
A subsequent study of the prevalence of Chronic Respiratory Symptoms
was conducted in Chattanooga in 1971 using the same methods as in the
initial study.
The results are shown in Table 6. Among individuals living in
their respective communities for a minimum of two years who had no
known history of occupational exposure to irritant dust and fumes.
There was no difference in prevalence of chronic bronchitis, among
the three communities in those under 40 years of age, but there was a
higher prevalence in those 40 years and over living in the formerly
designated high pollution area although these differences are not statistically
significant. These fingings are comparable to those of Shy e_t al_ in the
initial study suggesting a residual effect from previous exposure.
-------
Table 3. HOURLY NITROGEN DIOXIDE CONCENTRATIONS OBSERVED AT CHATTANOOGA AIR MONITORING STATIONS1
NAPCA
Community abatement
exposure station no.
High 19
15
17
20
Intermediate 161
Low —
CHESS
station no.
31
32
33
34
21
22
41
Year
1968
1972**
1973
1968
1970
1971
1972**
1973
1968
1970
1971
1972**
1973
1968
1972**
1973
1968
1972**
1973
1968
1972**
1973
1968
1972**
1973
Annual
- avg.
" 395
91
60
150 -
40
55
46
44
170
54
52
49
39
263
36
31
150
42
41
56
63
43
56
90th
percenti
1203
256
133
301
94 .
113
84
85
489
122
113
94
73
865
81
66
320
73
75
94
no
74
99
Hourly values
99th
le percenti le
3290
682
429
1128
188
226
193
150
2068
414 :
320 . .
273
235
2670
270
150
1448
115
122
160
160
113
142
Maximum
7144
906
997
3384
564
940
669
752
4606
1109
1128
599
752
7144
627
376
2914
154
700
270
338
188
216
*1968, 1970 and 1971 concentrations measured by Saltzman method. 1972 and 1973 concentrations measured by
chemiluminescence method.
**0nly last four months of 1972 monitored.
-------
TABLE 4
Maximum Hourly N02 Concentrations by Community and Station
Chattanooga, Tennessee, 1970-73*
(mierograms per cubic meter)
ommunity
exposure
High
Inter-
mediate
Abatement
Station
dumber
19
15
' 17
,,
, .
20
161
1
Low
1
CHESS
Station
Number
31
32
33
34
21
22
41
YEAR
°72
°73
A70
A71
°72
°73
A70
A71
°72
°73
°72
°73
°72
°73
°72
°73
°72
°73
Annual *
arith-
averane
346
230
106
152
116
103
222
165
164
127
123
87
77
87
105 •
113
85
105
IT— Nitrogen Dioxide : uq/m )
90th 99th Maximum
Percenti le Percentile
815 905 906
522 864 977
225 488 564^'
270 526 940
228 530 669
157 398 752
450 1090 1109
350- 690 1128
304 549 599
235 655 752
272 485 627
169 257 376
116 150 154
124 188 700
143 265 270
164 248 338
113 159 187
150 183 216
0 CHESS Chemiluminescent
A CHESS Saltzmnn
-------
Table 5
Smoking Adjusted Chronic Bronchitis
Prevalence (Percent) in the Main Study Group
Sex
Female
Male
Age
39
40
39
40
Exposure Area of Residence
Low
5.3
6.6
6.4
11.6
Intermediate
6.7
9.0
3.7
10.3
High
6.3
12.3
6.1
17.6
-------
However the prevalence rates of those males living in the neighborhood
who were continuing to experience high short term peak exposures to NOg
accompanied by elevated levels of suspended nitrates both age groups in
the high sxposure neighborhood had higher prevalence rates than did their
counterparts in all the other communities: 8.8% compared to 6.5% in those
39 years of age and under, and 15.5% compared to 11.6% in those over 39
years of age. Although these differences are not significant they do suggest
that prior high exposures coupled with current peak exposures may be sufficient
to trigger the onset of chronic respiratory disease.
Lower Respiratory Disease and Nitrogen Dioxide Retrospective Survey
in Chattanooga. Tennessee 1971
c
In another study acute lower respiratory disease morbidity was
surveyed retrospectively among children aged 1 to 12 years from the
three original CHESS communities that had represented an exposure gradient
for NCL (Table 6). The current study encompassed the period from 1969 to
1971. Lower respiratory disease morbidity rates among children of
residential families residing in areas exposed to high and intermediate
levels of nitrogen dioxide continued to be significantly higher than
those of comparable children living in a low exposure area. Furthermore,
lower respiratory illness rates in intermediate exposure neighborhoods
were significantly lower than rates in the high exposure community.
Because this study was not designed to determine yearly rates, it was
not possible to assess whether the significantly higher rates in the
intermediate and high exposure communities were consistent over the
three study years or were heavily weighted by the single year 1969, when
annual mean N02 levels were above the primary standard. Similarly, it
was not possible to distinguish residual effects of previous long term
exposure from effects of recent short term exposure.
-------
Hammer .-CT/LRD
11/29/74
Table 6
Three Year Frequency of "Any Lower Respiratory Disease" and Bronchitis:
Model Predicted Rates for Children Aged 1 to 12 Years
from Households with a High School Education or Greater
Morbidity
Condition
"Any Lower
Respiratory
Disease"
(
Bronchitis
Number of
Episodes
One
or
Mpre
Male
Female
Two
or
More
One
or
More
Two
or
More
Male
Female
Male
Female
Model Predicted* Rates, %
I-Low
28.3
28.0
14.0
12.2
9.8
4.4
4.2
II-Intermediate+
28.9
30.9
17.0
13.9
16.1
8.8
9.8
Ill-High
38.5
36.5
20.2
19.8
20.0
10.5
9.6
High/Low
Community
(p <0.01)
1.36
1.30
1.44
1.62
2.04
2.39
2.29
*Age, education head of household adjusted rates for nonasthmatic children
with three or more years residence duration.
+Intermediate exposure community significantly higher than low exposure
community in 5/8 sex by number of episode categories but significantly
lower than high exposure community in only 2/8 categories.
-------
Incidence of Acute Respiratory Disease. Chattanooga. Tennessee 1972-19738
A prospective study of acute respiratory disease comparable to that
of Shy et al was conducted in 1972 and 1973 in the three CHESS communities
in Chattanooga. In the 1972 study the excess risk of acute respiratory
disease remained consistently higher in those living in the formerly
designated high pollution community compared to those in the low
pollution community (Table 7). The highest excess risk (50 percent) was
observed in pre-school children. The intermediate exposure community
also showed excess risk in the lower respiratory disease compenent com-
pared to the low pollution community. Moreover, the excess risk for total
respiratory disease was not as great in the intermediate community as that
observed for the high pollution community. Pre-school children living
in the intermediate exposure area had a lower excess risk than other age
groups in that community. In the second year of study the pattern of
excess risk persisted across the three communities but the excess risks
themselves were lower than the preceeding year.
The excess risks of acute respiratory disease in the 1972 study
were similar to those found in the earlier 1968-69 Chattanooga study.
Although the annual average N02 levels in the initial study were sub-
stantially higher than those found in 1972 short term 90th percent!le
hourly N02 exposures associated with an effect were similar in the two
studies. At this time it is not known if those families living in
the neighborhood experiencing the highest short term exposures of N02
as well as elevated levels of suspended nitrates contributed excessively
to the added risk for the total high exposure community.
-------
o I / r\t\u
1/20/75 - Draft ,
TABLE 7
Relative Risk for Two Study Periods of Acute Respiratory Illness for Stable
Families Living in Communities Exposed to Differing Levels of Air Pollution3
Family
Segment
Mothers
Fathers
School
Children
Pre-School
Children
Sector
1
2
3
1
2
3
1
2
3
1
2
3
Acute Respiratory Illness
Involving Upper Tract
Study I
1.00(4.53)
1.24
1.28
1.00(3.06)
1.08
1.28
1.00(5.06)
1.19
1.31
1.00(7.00)
1.03
1.51
Study II
1.00(2.15)
1.00
1.20
1.00(1.52)
.81
1.81
1.00(2.50)
1.06
1.14
1.00(3.69)
.79
1.01
Involving Lower Tract
Study I
1.00(1.65)
1.16
1.68
1.00(1.20)
1.48
1.55
1.00(1.84)
1.58
1.48
1.00(3.56)
1.12
1.55
Study II
1.00(2.17)
1.17
1.05
1.00(1.75)
.95
.92
1.00(2.84)
1.10
1.31
1.00(5.01)
.92
1.35
All Respiratory Illnesses
Study I
1.00(6.24)
1.21
1.40
1.00(4.30)
1.19
1.36
1.00(7.05)
1.28
1.34
1.00(10.69)
1.07
1.51
Study II
1.00(4.41 )
1.10
1.12
1.00(3.35)
.89
1.04
1.00(5.44)
1.08
1.22
1.00(8.81)
.87
1.21
aStudy Period I—January 23, 1972 to May 21, 1972.
Study Period Il-September 10, 1972 to April 28, 1973.
Base Rate in parentheses refers to illnesses per 100 person weeks of risk.
-------
The persistence of excess risk for acute respiratory disease four
years after long term exposure has decreased may reflect residual effects
from the previous prolonged exposure or the effects from intermittent high
peak exposures or both of these factors. The findings in the pre-school
children in the 1972-1973 study suggest the latter may be the case. The
pre-school children in the high pollution community had limited prolonged
exposure to high annual average levels of No2 but did have short term high
exposure, yet these children showed the highest excess risk in their
community. Their counterparts in the intermediate community had neither
prolonged exposure to high annual average levels of NO- nor to high short
term exposures and they had the lowest relative risk in their community.
This suggests that intermittent high peak exposures to N02 may contribute
to excess risk of .acute respiratory disease in the absence of excessive
long term exposure. However, excess risk persisted in the other age groups
living in the intermediate exposure community suggesting a residual effect
3
from previous annual average exposure of 150 ug/m or 90th percentile hourly
3
exposures of 300 ug/m .
Ventilatory Function in School Children in Chattanooga, Tennessee
Studies showed ventilatory function of children in Chattanooga was
not longer impaired two years after annual exposures were reduced from
3 3
150-395 ug/m to 45 ug/m even though short-term peak hourly exposures
3
continued to range from 228 to 814 ug/m for ten percent of the days
each year.
Asthma Panel Studies
In a recent study conducted in the New York-New Jersey Metropolitan
area as part of the EPA-CHESS program, daily variations in pollution
levels were compared to daily variation in the asthma attack rate.
-------
This study showed increased asthmatic attacks were significantly associated
with elevated levels of suspended nitrates in six of the seven communities
studied. (Table 8). No such effect was observed with NOp. Chemilumi-
nescence instruments showed NCL levels met the annual average standard
at a central city station but only the Jacobs-Hochheiser method was used
for measurement of N(L in the study neighborhoods themselves. In another
CHESS study in two Southeast communities, there was some evidence of
excess risk of asthmatic attacks associated with elevated levels of
suspended nitrates but the findings were less consistent than those
observed in the New York study. In the Southeast, the combination
of suspended nitrates and suspended sulfates contributed to greater
excess risk of asthma attacks than did either pollutant alone.
Because of problems in the present method of measuring and analyzing
suspended nitrates, the findings in these studies should be viewed quali-
tatively rather than quantitatively. The results of these two studies
raises the question with respect to the appropriate levels of N0? which
might be necessary to prevent levels of transformation products such as
nitrates which in themselves may contribute to adverse health effects.
-------
Table 8. Summary of Partial Regression Coefficients in Multiple Regression Analysis
r_nr.15 NS
.0009 .0101 .0050 .0043
.0328* .0022 .0163 .0261*
.0070 .0308*- .0060 .l)0<.3
.0014 .0410 .0020 .0025
.0027 .0160* .0004 .0133
.0035 .00018 .0026 .OC25
.OC39 .0134 .0137 .Cl£3-
MS = Non Sn.okers
* - p= 0.05
**.-_P.= .Q.OJ
-------
DISCUSSION
The findings in the subsequent Chattanooga studies suggest that:
1. Exposure to prolonged levels of nitrogen dioxide ranging from
113 to 395 ug/m in combination with short-term exposures of 301 to
1203 ug/m may contribute to excess risk of acute respiratory
disease and the residual effects from this exposure may last for
as long as four years.
o
2. Repeated short term exposures of 228 to 815 ug/m may contribute
to excess risk of acute respiratory disease in the absence of
excessive long term exposures.
3. Prior high short term and long term exposures to N0?
coupled with continous excessive short term exposures might
trigger the onset of chronic respiratory disease symptoms.
These epidemiological findings support those from the animal studies
reported by Dr., Gardner and others here this afternoon.
Because of the limitations of the aerometric measurements in these
epidemiologic studies, the results should be viewed qualitatively rather
than quantitatively and the levels at which effects were observed should
not be construed as threshold levels.
Additional epidemiologic and clinical studies are needed that are
specifically designed to measure health effects from short term peak
exposures to NO- using appropriate aerometric measurement methods.
The significant association of suspended nitrates with the asthma
attack rate also supports recent findings from studies showing increased
histamine release from guinea pig lung mast cells by sulfates and nitrates
in the presence of the ammonium ion. The lack of a standardized method
for collecting and analyzing suspended nitrates also poses a problem in
determining appropriate estimated threshold levels of suspended nitrates
associated with the exacerbation of asthma. It is necessary that a
concerted research effort be launched to address these important problems.
-------
REFERENCES
1. Shy, C.M. et al. The Chattanooga School Children Study: Effects of
Community Exposure to Nitrogen Dioxide. Incidence of Acute Respiratory
Illness. J. Air Pollution Control Assoc. 20 (9): 582-588, September
1970.
2. Shy, C.M. et al. The Chattanooga School Children Study: Effects of
Community Exposure to Nitrogen Dioxide. I. Methods, Description of
Pollutant Exposure and Results of Ventilatory Function Testing. J.
Air Pollution Control Assoc. 20 (8): 539-545, August 1970.
3. Pearlman, M.E., et al. Nitrogen Dioxide and Lower Respiratory Illness.
Pediatrics 47 (2): 391-398, February 1971.
4. Chattanooga, Tenneessee - Rossville, Georgia Interstate Air Quality
Study 1967-1968. U.S. Public Health Service National Air Pollution
Control Administration Publication No. APTD-0583, Durham, N.C.
5. Shy, C.M., L. Niemeyer, L. Truppi and T. English. Re-evaluation of
the Chattanooga School Children Studies and the Health Criteria for
N0~ Exposure. In-house technical report, National Environmental Re-
search Center,-EPA, Research Triangle Park, N.C. March 1973.
6. Galke, W., and D. House. Prevalence of Chronic Respiratory Disease
Symptoms in Chattanooga, Tennessee 1971. (Unpublished data).
7. Hammer, D., and F. Miller. Lower Respiratory Disease and Nitrogen
Dioxide Retrospective Survey in Chattanooga, Tennessee, 1971.
8. Riggan, W. et al. Acute Respiratory Disease in Chattanooga Tennessee.
1972-1973. (Unpublished data).
9. Stebbings, J., D. Hasselblad, R. Chapman, and K. McClain. Venti-
latory Function in School Children. Chattanooga. 1971-1972
(Unpublished data).
10. French, J.G., V. Hassleblad, R. Johnson. Aggravation of Asthma by
Air Pollutants. 1971-72 New York-New Jersey Metropolitan Communities.
(Unpublished data).
11. French,, J.G., V. Hasselblad, R.J. Johnson. Aggravation of Asthma
by Air Pollutants. 1971-72 Southeastern CHESS Studies. (Unpublished
data).
12. Charles, J., D. Munzel. Ammonium and Sulfate Ion Release of Histamine
from Lung Fragments. In Press. Archives of Environmental Health.
-------
L. DR. SAMUEL EPSTEIN
NITROSAMINES
-------
Copies of this paper were unavailable for printing. Copies of the
transcript of this portion of the seminar are available for purchase from:
Ace-Federal Reporters, Inc.
415 2nd Street, N. E.
Washington, D. C. 20002
(202) 547-6222
-------
M. DR. DANIEL MENZEL
IMPLICATIONS OF THE MOLECULAR MECHANISMS
OF NO2 INTOXICATIONS TO PUBLIC HEALTH
-------
Copies of this paper were unavailable for printing. Copies of the
transcript of this portion of the seminar are available for purchase from:
Ace-Federal Reporters, Inc.
415 2nd Street, N. E.
Washington, D. C. 20002
(202) 547-6222
-------
SECTION 4
TUESDAY
-------
A. DR. JOHN KNELSON
HEALTH EFFECTS OF OXIDANTS AND
CARBON MONOXIDE
-------
HEALTH EFFECTS OF OXIDANT EXPOSURES: A RESEARCH PROGRESS REPORT
John H. Knelson, M.D.
Director
Human Studies Laboratory
National Environmental Research Center
Environmental Protection Agency
Research Triangle Park, North Carolina 27711
Prepared as a supporting document for
an oral presentation to the
California Air Resources Board Conference,
"Technical and Medical Bases for Control Strategies of
Photochemical Oxidant: Current Status and
Priorities in Research", December 16-17, 1974.
December 9, 1974
-------
NOTICE
This document is a preliminary draft.
It has not been formally released by
EPA and should not at this stage be
construed to represent Agency policy.
It is being circulated for comment on
its technical accuracy and policy
implications.
-------
Contributors:
David Coffin
Donald Gardner
Ronald Harvey
Carl Hayes
Dennis House
Gory Love
Wendell McKenzie
Mirdza Peterson
Nicholas Rummo
-------
Table of Contents
Page
Introducti on 1
Mechanisms of Toxicity 2
PIanning a Research Strategy 3
Clinical Studies 6
Epidemiology , 13
Toxi col ogy 18
-------
INTRODUCTION
Does the current U.S. Ambient Air Quality Standard for photochemical
oxidants (160 yg/m3 maximum one hour concentration) adequately protect, with
a reasonable margin of safety, the public health? The U.S. Environmental
Protection Agency has in progress a comprehensive research program designed
to provide the answer to that question. Studies of humans, upon which the
current standard was based, demonstrated the deleterious effects of photo-
chemical oxidants on resistance to respiratory infections, respiratory
tract and eye irritation, exacerbation of symptoms in persons with chronic
lung disease, decrement in lung function, and impaired exercise performance.
Studies of animals corroborated these findings and, in addition, suggested
that increases in cytogenetic abnormalities and fetal wastage, as well as
interference with immune mechanisms may occur with exposure to levels of
ozone occurring in ambient air. Current research is continuing to explore
the influence of photochemical oxidants on the respiratory disease experience
and exacerbation of symptoms in healthy, as well as susceptible populations.
Clinical studies are evaluating several other health parameters. Toxicological
studies continue to demonstrate effects of relatively low level ozone exposure
on a variety of metabolic functions. The implications of these studies
as they relate to the air quality standard issue is the basis of this
presentation.
-------
Photochemical Oxidants: Research in Progress
• POPULATION STUDIES
ASTHMA ATTACK RATES
EXACERBATION OF SYMPTOMS
CHROMOSOMAL ABNORMALITIES
t CLINICAL STUDIES
CARDIOPULMOMARY FUNCTION
PSYCHOPHYSIOLOGIC FUNCTION
CHROMOSOMAL ABNORMALITIES
IMMUNE STATUS
CARCINOMA-ASSOCIATED ANTIGENS
METABOLIC EFFECTS
EVALUATION OF COSTRESSORS
t TOXICOLOGY
LUNG INTEGRITY
IMMUNE STATUS
METABOLIC EFFECTS
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-2-
Mechanisms of Toxicity
Ozone is known or suspected to exert its deleterious effect by a variety
of mechanisms. These may be separated conveniently into two categories:
those effects resulting from the action of ozone as a direct respiratory
irritant, and those associated with its ability to act as a generator and
propagator of free radicals or other reactive molecules such as ozonides.
Some of the earliest research in ozone toxicology described alterations in
the mechanical function of lung, associated with acute exposure. These were
expressed as decrements in vital capacity, forced expiratory volume, flow
rates, and airways resistance. Changes of this nature could be expected if
ozone acted as a non-specific upper airway irritant to initiate a neurogenic
response resulting in small airways constriction. Alternately, the direct
action of ozone on respiratory mucosa with even a minimal resulting edema
would be associated with narrowing of the small airways leading to the observed
change in lung mechanical function. Although there is a paucity of data
associating changes in cardiac performance with ozone exposure, one would expect
a cardiac effect secondary to the change in lung function, especially in persons
already suffering cardiac impairment because of pre-existing illness. Changes
in small airways dynamics, as well as alterations in the mucociliary clearance
mechanisms would explain at least part of the increased respiratory illness
experience associated with chronic photochemical oxidant exposure in populations.
It is quite likely that ozone serves to generate and propagate free radicals
and/or other reactive molecules in biologic systems. Initiation of the se-
quence of events resulting in formation of these reactive compounds would
explain observed changes in the integrity of the organism not directly associated
with the effects of ozone on the respiratory system. One would expect that free
radical generation could result in changes in nucleic acid synthesis, alteration
-------
Mechanisms of Toxicity
RESPIRATORY IRRITANT
ALTERED LUNG MECHANICS (ACUTE)
ASSOCIATED CARDIAC EFFECT
ALTERED CLEARANCE
FREE RADICAL GENERATOR
. NUCLEIC ACID SYNTHESIS
CYTOGENETIC EFFECT
CARCINOGENESIS
MUTAGENESIS
TERATOGENESIS
IMMUNE STATUS
PROTEIN STRUCTURE
ALTERED LUNG MECHAMCIS (CHRONIC)
IMMUNE STATUS
METABOLIC EFFECTS
MEMBRANE INTEGRITY
IMMUNE STATUS
METABOLIC EFFECT
PSYCHOPHYSIOLOGIC EFFECT
DIRECT CARDIAC EFFECT
-------
-3-
in protein structure, and interference in the function of cell and organelle
membranes. An interference with nucleic acid synthesis could result in
cytogenetic alterations similar to those associated with carcinogenesis,
mutagenesis, and teratogenesis. By the same mechanism one could anticipate an
alteration in cellular immune status. Oxidation of protein cross-linkage would
result in the observed chronic effects on lung structure, as well as function.
Similar changes in antibody structure would account for the postulated impair-
ment of humoral immune status. Metabolic effects such as changes in serum
enyzme levels associated with a specific organ damage could also be expected
as a result of alteration in the protein structure of the cellular proteins or
the enzymes themselves. It is known that ozone exposure can result in perox-
idation of lipoprotein cellular membranes. Such changes might be expected to
cause a decrement in cellular immune status such as that associated with
chemotactic or phagocytic activity. Alterations in cell membrane function
resulting in leakage of intracellular contents could be expected to result in
elevation of certain serum enzyme levels. Oxidation of red blood cell membranes
may interfere with oxygen carrying capacity, which in turn could impair the
central nervous system, as well as cardiac performance.
With these possible mechanisms of toxicity in mind, we have designed a
research strategy to evaluate the biological significance for man of repeated
exposures to low levels of oxidant air pollution.
Planning a Research Strategy
The design of a coherent program to evaluate the human health effect of
environmental factors is a complex undertaking. Four of the most important
aspects of such a program, however, are the following:
(1) Definition of the most likely clinical changes associated with known
or suspected mechanisms of toxicity.
-------
-4-
(2) Description of the concentration and distribution of the toxic en-
vironmental agent in the biosphere.
(3) Description of the nature, size, and distribution of the population
at risk.
(4) Evaluation of potential co-stressors.
The usual techniques of epidemiology, clinical studies, and basic toxicology
permit, in varying degrees, an approach to these four aspects of environmental
health effects research. The strengths and limitations of the three disciplines
are well understood and appreciated. Somewhat less thought, however, has been
given to the difficulties encountered in deriving an exposure density function
for populations. The basic question is "How many people in various suscepti-
bility categories are exposed to what levels of which pollutants and for how
long?" Answering this question is essential to the development of a meaningful
human damage function.
The United States Environmental Protection Agency is approaching this
problem by developing technology in four separate areas:
(1) Environmental monitoring
(2) Regional modelling
(3) Clinical research in controlled environmental laboratories
(4) Application of clinical research methods to population studies
Improved air monitoring has been achieved through use of more accurate and
specific sensors capable of providing measurements with very short averaging
times. The use of such principles as chemiluminescence has made possible the
development of semi-automated monitoring stations which themselves are directed
and calibrated by small on-board computers. These monitoring stations are
sited in selected urban locations throughout the United States and feed their
data by telephone lines into a command central computer located in our research
-------
-5-
headquarters in North Carolina. Thus the air quality of regions in which we
are conducting health studies can be monitored constantly.
Such monitoring, however sophisticated it is, does not give adequate
dose data for the recipient population. Meteorologic conditions cause constantly
varying pollutant isopleths around the monitoring stations. Use of dispersion
models provides a method for better estimation of local pollutant concentrations.
These models are validated or improved by mobile monitoring stations.that can
make many intermittent analyses throughout a region, as well as by monitoring
grids established specifically for that purpose. Because people do not remain
stationary in a given region, activity profiles are being developed to model
their movements through pollutant gradients. Classic methods of epidemiology,
used with these estimates of population dose, provide the data base for our
Community Health and Environmental Surveillance System - a systematic assessment
of associations between environmental factors and public health. In addition,
targeted epidemiologic studies designed to answer specific questions are con-
ducted.
Interpretation of data from population studies is fraught with many well-
known difficulties. When possible, it is desirable to corroborate the
epidemiologic findings with those of carefully controlled clinical studies.
The standard techniques of the clinical scientist are used to assess transient
and subtle changes in the health status of his subjects. Not standardized,
however, are the techniques for manipulating and controlling the subjects'
environment. Controlled Environmental Laboratories of relatively simple design
have been in use for several years, but just coming into existence is a second
generation of these laboratories which will use the same instruments to control
the interior environment as are used in our cities to measure the ambient
environment. Control mechanisms linked to these monitoring instruments provide
the capability for programming diurnal pollutant cycles to simulate those
-------
FIGURE 1
DAILY MAXIMUM HOURLY AVERAGE OZONE CONCENTRATION
1000
900
800
700
600
500
400
300
200
0.0
j; 100
§ ,9S
M 80
0 70
60
50
40
30
20
10
'GLENDORA
101 30 50i 70 90i 95 99
CUMMULATIVE FREQUENCY
-------
FIGURE 2
1000
900
800
700
"7-. 600
OJ
UJ
13 500
o
400
300
200
100
OZONE DIURNAL FLUCTUATION
GLENDORA
JilNE 5-7, 1973
1 AVERAGE
171
4 8 12
JUNES
16 20 24 4.8
16 20 24 4
JUNE 6
8 12
JUNE 7
16 20 24
-------
-6-
occurring in urban areas.
One of the principles followed in designing clinical environmental studies,
is that the exposure schedule should not generate a stress in excess of that
being placed on large numbers of people breathing ambient air. This principle
emphasizes once more the importance of accurate and detailed air quality data.
Our current clinical studies of ozone can serve as a useful example of how
air quality data are interpreted for experimental design. For example, in
Figure 1 it is seen that during two months of the year in Glendora, California
the daily maximum hourly average ozone concentrations equalled or exceeded
600 yg/m3 about ten percent of the time. Thus, on the average, at least one
hour each day for 36 days that year, people in Glendora were exposed to a
minimum of 600 yg/m3 of ozone. But what might have been peak and hourly con-
centrations just before and after the daily maximum hourly average? Figure 2
shows that; for days when the maximum hourly average is 600 yg/m3 or greater,
peaks may be as much as 100 yg/m3 higher than the maximum hourly average, but
preceding and succeeding hourly concentration could be 100 yg/m3 or more lower.
An automated air monitoring system provides much more rigorous analysis of
such exposure profiles for purposes of calculating population damage functions,
as well as designing controlled environmental studies.
Clinical Studies
To date, most studies investigating effects of ozone in human volunteers
in a controlled setting have focused on pulmonary effects. Bates and co-workers
demonstrated decrements in lung function after one hour and two hours of ex-
posure to levels of ozone of 740 yg/m3. Kerr recently exposed healthy volunteers
to 1000 yg/m3 ozone for six hours and demonstrated decrements in certain pa-
rameters of lung function after four hours of exposure to this concentration.
-------
-7-
There exists a body of information demonstrating ozone effects on other
organ systems in animals. Chinese hamsters, following a five hour 400 ug/m3
exposure to ozone were found to have chromosomal abnormalities in circulatory
lymphocytes not found in a control group. These results confirmed previous
findings of increased numbers of chromosomal abnormalities occurring in human
cells exposed in vitro to 16 mg/m3 (8 ppm or 16000 pg/m3) for 5 to 10 minutes.
Other animal studies have found that ozone exerts an effect on phagocytic
ability of pulmonary alveolar macrophages, after three hour exposure to 1340
ug/m3 ozone. Further studies demonstrated increased susceptibility to respira-
tory infections in mice and hamsters following exposures from 2.6 to 8.8 mg/m3
ozone.
Proceeding from this data base we initiated experiments to evaluate the
effects of ozone on:
(1) Lung function
(2) Chromosomal abnormalities
(3) Lymphocyte transformation
(4) Neutrophil adherence and chemotaxis
(5) Neutrophil phagocytic and killing index
(6) Carcinoma - associated antigen titres
(7) Serum enzyme levels.
These studies are still in progress but some interesting preliminary re-
sults have been obtained.
Males between the ages of 20-27 are given a four hour exposure to 800
vg/m3 ozone in a precisely controlled plexiglass environmental chamber measuring
8' x 8' x 8'. This level was chosen since it closely approximates oxidant
levels occurring in the Los Angeles basin during pollution episodes and was one
of the significant harm levels described in the Federal Register of October 23,
-------
-8-
1971. The experimental protocol was approved by the University of North
Carolina Committee for protection of human subjects operating under existing
DHEW guidelines. All subjects completed comprehensive medical history
questionnaires and were examined by a physician. No subject was accepted who
had a history of respiratory, allergic or cardiac illness, or who was a smoker.
Ozone is generated by flowing bottled oxygen through a silent arc ozonator.
Accurately calibrated chemiluminescence analyzers, currently used by EPA CHAMP
stations monitor the ozone level in the chamber. A feedback system from the
analyzer controls oxygen flow through the ozonator, and thereby keeps the ozone
level within very narrow limits. Ozone levels are equal and constant in all
parts of the chamber and during the exposures have been within the limits of
700 to 840 pg/m3 at all times. The temperature is maintained between 70-76°F
and relative humidity at 40-60%.
During the ozone exposure the subjects are seated in the chamber except
for two exercise periods. At the one and three hour points each subject
exercises on a bicycle ergometer for 15 minutes at 700 kg-meters, a level
sufficient to increase minute ventilation fourfold. ECG is continuously
recorded at rest and during exercise. At the two hour point subjects are re-
moved from the chamber for approximately 15 minutes for pulmonary function
testing.
The parameters measured include forced vital capacity (FVC), forced ex-
piratory volume in one second (FEVj), maximal mid expiratory flow rate.(MMEF),
forced expiratory reserve volume (FERV), and forced expiratory reserve volume
at one second (FERVi). In addition, flow volume tracings are recorded and
measurements of airway resistance and thoracic gas volume are made using a
body plethysmograph.
Spirometry is performed with a 12 liter low resistance, dry-seal rolling
-------
-9-
spirometer (CPI, model 220). Paper tracings are recorded on a X-Y plotter.
Simultaneously the differentiated volume signal from the spirometer is dis-
played on the Y axis of a Tektronic 564 B storage oscilloscope, the volume
being displayed on the X axis thus giving the flow-volume trace. Polaroid
photographs are taken for analysis of the tracing. Three forced vital capacity
maneuvers are made at each testing point, and the maximum vital capacity
is later analyzed. The flow-volume tracing showing the highest peak-flow
rate is chosen for complete analysis. Airway resistance and thoracic gas volume
are measured in a constant displacement body plethysmorgraph (CPI #1100), using
the method of Dubois, et al.
Subjects participate in a control session breathing ambient Chapel Hill
air in the chamber three days prior to the ozone exposure. Before the control
session the subjects are trained in the performance of the pulmonary function
studies. The four hour control session is similar in all respects to the sub-
sequent ozone exposure. Control and ozone exposures take place from 9AM -
1:15PM for all subjects. Baseline pulmonary function measurements are performed
before entering the chamber and after two and four hours of exposure to ambient
air or ambient air plus ozone. Following air and ozone sessions, subjects
fill out a questionnaire describing symptoms that might result from ozone ex-
posure. These include cough and chest discomfort, as well as sham symptoms of
abdominal and joint pain that could not reasonably be associated with ozone
exposure.
At the present time the results from only some of the spirometric measures
have been analyzed. The results of FVC, FEVls and MMEF measures for 16 subjects
are shown in Tables I-III. Analysis of variance was performed comparing results
at two and four hours with the baseline measure.
A significant decrement in FVC and MMEF is seen after two hours of ozone
exposure (p = .019 FVC, p = .048 MMEF) and after four hours FVC (p < 0.001),
-------
TABLE I
ANOVA: FORCED VITAL CAPACITY
N = 16
SOURCE
(BETWEEN SUBJECTS)
(WITHIN SUBJECTS)
EXPOSURE
TIME
EXP. X TIME
2 HR. CHANGE AIR VS.
2 HR. CHANGE 03
4 HR. CHANGE AIR VS.
4 HR. CHANGE 03
ERROR
TOTAL
P.P.
(15)
(80)
1
2
2
1
1
75
95
SS
(31.5593)
(5.0167)
1.1354
1.0896
0.4788
2.3129
36.5760
MS
1.1354
0.5448
0.2394
0.1764
0.4709
0.0308
F
36.86
17.69
7.77
5.73
15.29
P
p < .001
p < .001
p < .001
p = .019
p < .001
-------
TABLE II
ANOVA: FEVX
N = 16
SOURCE
(BETWEEN SUBJECTS)
(WITHIN SUBJECTS)
EXPOSURE
TIME
EXP. X TIME
2 HR. CHANGE AIR VS.
2 HR. CHANGE 03
4 HR. CHANGE AIR VS.
4 HR. CHANGE 03
ERROR
TOTAL
P.P.
(15)
(80)
1
2
2
1
1
75
95
SS
(22.9701)
(7.6515)
1 .8984
0.8895
1.0263
3.8373
30.6216
MS
1.8984
0.4448
0.5132
0.1796
1.0176
0.0512
F
37.08
8.69
10.02
3.51
19.88
P
p < .001
p < .001
p < .001
p = .065
p < .001
-------
TABLE III
ANOVA: MMEF
N = 16
SOURCE
(BETWEEN SUBJECTS)
(WITHIN SUBJECTS)
EXPOSURE
TIME
EXP. X TIME
2 HR. CHANGE AIR VS.
2 HR. CHANGE 03
4 HR. CHANGE AIR VS.
4 HR. CHANGE 03
ERROR
TOTAL
P.P.
(15)
(80)
1
2
2
1
1
75
95
SS
(85.224)
(77.001)
2.870
0.341
2.447
21.343
112.225
MS
2.870
0.170
1.224
1.156
2.314
0.285
F
10.07
0.60
4.29
4.06
8.12
P
•
p < .01
p < .05
p = .048
p = .006
-------
-10-
MMEF (p = 0.006), and FEVi, (p < 0.001) are impaired. Flow-volume tracings
show similar overall percentage decrements for peak flow and flow at 50%
vital capacity after two and four hours of ozone exposure, but analyses are
not yet complete. Airway resistance was approximately 10-15% less after four
hours of exposure.
Thirteen of the sixteen subjects reported mild or moderate chest discomfort.
Eight of the sixteen reported a mild cough. None of the subjects responded
positively to the sham questions on abdominal or joint pain.
These results demonstrating pulmonary function changes after two hours of
ozone at 800 yg/m3 agree very well with the results reported by Bates and co-
workers. Decrements are somewhat more marked than those shown by Kerr in
nonsmokers. He found no statistically significant results in pulmonary function
after two hours of exposure at 1000 yg/m3. The group of subjects reported here
is larger,than that of Bates and more homogeneous than that studied by Kerr;
this may account for the slightly differing results.
One can conclude that changes in pulmonary function occur in healthy adult
males at concentrations reached in urban environments. The extent of pulmonary
function impairment in susceptible groups could reasonably be expected to be
higher than those found here.
The phagocytic and bactericidal processes of leukocytes are measured by
the capability of polymononuclear neutrophiles to phagocytize and kill micro-
organisms of respirable size. For this study blood is drawn immediately prior
to exposure, immediately after the four hour exposure and at 72 hours, two
weeks and one month post exposure. We use the method by Sbarra, et al. which
has been employed extensively in demonstrating the defects found in chronic
granulomatous disease of children. Leukocytes obtained via differential
sedimentation techniques are purified by passing them slowly through the plunger
-------
-11-
of a Teflon homogenizer. The polymorphonuclear neutrophile counts, made in a
hemocytometer chamber, range from 40 to 76%. The test is performed in two
series of siliconized flasks consisting of suspensions of staphylococcus
epidermidis (18 hour culture, washed), autologous serum, and Hank's Balanced
Glucose (HBG). The bacteria/cell ratio is chosen to produce maximum phagocytosis.
After five minutes incubation at 37°C, the polymorphonuclear neutrophile suspension
is added to one set of flasks, and HBG to the other series. The latter serves as
the bacteria-serum control. The two sets are incubated in a rotating shaker
(100 rpm) at 37°C. At 30 and 60 minute intervals an aliquot is removed from each
set, diluted, and plated with "pour plate" technique for the total viable
bacterial count. Next, an aliquot from the experimental flask is removed,
added to a portion of HBG and centrifuged. An aliquot of the supernatant is
diluted and plated for the total extracellular bacterial count. The cellular
pellet is homogenized and plated for the total intracellular bacterial count.
All counts are expressed as colony-forming units.
Results for phagocytosis were calculated by comparing the percent of
bacteria not phagocytized during control conditions after 60 minutes of in-
cubation to the percent of cells not phagocytized for the experimental conditions.
In order to perform analysis of variance to test significance, the proportion
of cells not phagocytized was converted to arc-sine values. Analysis of
variance for arc-sine values, as well as the actual percent of remaining bacteria
are shown in Table IV for 10 subjects for which complete data exist. There is
a fourfold decrease in phagocytic ability immediately after ozone exposure.
The impairment is even greater at 72 hours and begins to return towards normal
after two weeks. The values are significant for immediate post exposure
(p = .006) and at 72 hours (p < .001). Differences are not significant at
two weeks and one month (p = .084 for two weeks) and (p = .92 for one month).
The results for intracellular killing are as yet inconclusive. There is
-------
TABLE IV
ANOVA: PHAGOCYTOSIS
N = 10
SOURCE
(BETWEEN SUBJECTS)
(WITHIN SUBJECTS)
EXPOSURE
BEFORE VS. 4 HRS. AFTER
BEFORE VS. 72 HRS. AFTER
BEFORE VS. 2 WEEKS AFTER
BEFORE VS. 4 WEEKS AFTER
INCUBATION TIME
EXP. X IN. TIME
INTERACTION
ERROR
TOTAL
P.F.
(9)
(90)
4
1
1
1
1
1
4
81
99
SS
(941.98)
(1765.41)
388.89
2.32
23.81
1350.39
2707.39
MS
97.22
132.02
235.56
50.94
0.24
2.32
5.95
16.67
F
5.83
7.92
14.13
3.06
0.01
P
p < .001
p = .006
p < .001
p = .08
p = .92
-------
-12-
a trend toward diminished intracellular killing which is most striking at two
weeks post exposure; however, values from additional studies will be needed
before definitive conclusions can be drawn.
Preliminary results from 10 subjects demonstrated a statistically
significant decrease in phagocytic ability of neutrophils of young male adults
exposed to low levels of ozone. The most plausible explanation for this
finding is that the lipoprotein neutrophil membrane is damaged, and therefore
cannot function normally. Ozone is known to react with lipids producing free
radical intermediates and oxidizing unsaturated fatty acids. If there is a
demonstrable effect on intracellular killing two weeks after exposure, the
effect may be mediated by interference with intracellular enzyme synthesis.
Such an effect should not be expected to appear immediately.
These results are preliminary and more subjects are to be studied. If
these early findings are proved valid, they may help to explain some epidemi-
ological findings suggesting an increased respiratory infection rate in
children exposed to oxidizing pollution. Further studies now in progress,
are assessing the effect of ozone exposure on neutrophil chemotaxis and ad-
herence, as well as on lymphocyte transformation.
Animal and in vitro studies indicating a cytogenetic effect of ozone
exposure have led us to evaluate the magnitude of this effect in man. Blood
taken just prior to exposure, immediately after exposure to 800 yg/m3 ozone
for four hours, at 72 hours, two weeks and one month after exposure from the
same volunteers, was used to evaluate potential cytogenetic effects. Lympho-
cytes were cultured for 48 hours, slides made and metaphase spreads scored for
chromosome aberrations. Each slide was coded so that all cytological analyses
were made blindly, that is, without knowing the treatment involved.
Data from nine subjects have been analyzed. The sum of chromatid breaks
and gaps per 100 cells examined for each time interval after exposure was
-------
TABLE V
ANOVA: CHROMOSOMAL ABNORMALITIES
N = 9
SOURCE
(BETWEEN SUBJECTS)
(WITHIN SUBJECTS)
TIME
PRE VS. POST
PRE VS. 72 HRS.
PRE VS. 2 WEEKS
PRE VS. 1 MONTH
ERROR
TOTAL
P.P.
(8)
(36)
4
1
1
1
1
32
44
SS
(89.86)
(427.69)
152.97
274.71
517.55
MS
38.24
72.24
73.53
17.23
0.17
8.58
F
4.46
8.42
8.57
2.01
0.02
P
p = .006
p = .007
p = .006
p = .166
p = .888
-------
-13-
compared to the pre-exposure value of breaks and gaps. The percent of breaks
and gaps for each treatment is shown in Table V. For statistical purposes
these percents were transformed to arc-sine values and analysis of variance
performed. Statistically significant increases in chromatid breaks and gaps
were present immediately after exposure and 72 hours after exposure. No
differences were present at two and four weeks.
These preliminary studies of ozone-induced chromosome abnormalities have
demonstrated morphological damage to an important class of cells. Further
studies are required to validate the present results and plans are underway
to have these samples evaluated by other geneticists. If the results are
confirmed, important questions arise concerning possible oxidant mediated
effects on cellular function, mutagenesis and carcinogenesis.
In addition to evaluation of cardiopulmonary function immune status and
cytogenetic effects, subjects studied in EPA laboratories are providing data
on serum enzyme changes and carcinoma-associated antigen titers. Results
from these aspects of our program are too preliminary to discuss in any detail.
We have found no changes in serum aspartate ami no transferase, alkaline
phosphatase, gamma glutamyl transpeptidase, and ornithine carbamyl transferase.
Red blood cell phospholipid profiles were unchanged.
Epidemiology
Among the features unique to epidemiologic studies is the possibility
of assessing the effects on free living human beings in natural (as opposed
to simulated) pollutant exposures. Because of the difficulties in quantitating
the complexities of pollution exposure profiles, as well as the wide variation
of human response, no single study will provide conclusions which can confi-
dently be generalized.
-------
-14-
In an attempt to accumulate a credible data base for approaching the
questions of how air quality relates to human health, the Human Studies
Laboratory is currently conducting a substantial epidemiologic program which
addresses a variety of regulated and currently unregulated pollutants of
major concern to the agency. The studies which specifically address the
effects of ozone or photochemical oxidants include the following.
The Community Health and Environmental Surveillance System (CHESS) is
designed to provide temporal and spatial replications of a set of standardized
studies which relate sensitive health indicators to simultaneous measurements
of air quality. As a part of this program, which involves six areas across
the United States, seven communities in the Los Angeles Basin are being studied,
Although the major emphasis of these studies is directed toward effects
of ozone and nitrogen oxides, total and respirable particulates, S02 and CO
are also considered.
Health indicators utilized in CHESS can be classified as either effects
of short-term (i.e. = 4 days) or long-term exposure. This dichotomy is an
oversimplication because it is impossible at present to determine whether
long-term effects should be attributed to total integrated exposure or
repeated exposures of short duration.
Short-term indicators which have been utilized include: increases in
symptoms of irritation to the eyes and respiratory tract during high pollution
periods, exacerbation of cardio-pulmonary disease in panels of adults,
increases in attacks in panels of asthmatics. Long-term effects include:
frequency of acute lower respiratory disease in children, prevalence of
chronic respiratory disease in adults, incidence of acute respiratory disease
in families, and pulmonary function (FEV 75) in elementary school children.
-------
-15-
Many investigations of circulating peripheral lymphocytes in populations
of persons with histories of exposure to ionizing radiation have demonstrated
a radiation" dose-cytogenetic response relationship. Other investigations have
suggested that exposure to certain drugs and viral infections can cause
increases in the proportion of abnormal cells in peripheral lymphocytes.
Animal studies have indicated that ozone may be a particularly potent chromo-
somolytic agent. Because ozone is the primary constituent of photochemical
oxidants, it is of interest to determine if a higher proportion of populations
exposed to this type of air pollution carry aberrant cells than the nonexposed.
It is also of interest to determine if a continual increase in proportion of
aberrant cells occurs, and if aberrant cells are induced, is the process
reversible.
Samples of blood were taken from 150 freshmen entering the University
of Southern California. The bloods were collected as soon as possible after
the students arrived for registration. Half of the samples were from students
who have never lived in the Los Angeles Basin and half were from students
whose homes are in The Basin. The Los Angeles students were matched to the
non Los Angeles students by sex and college domicile.
Using standard techniques, lymphocytes were cultured and 100 cells scored
for a study of induced aberrations. The analysis included the assignment of
each chromosome, of each cell examined, to a given group of the Denver classi-
fication, determination of the chromosome number of each cell examined, as
well as noting the position on the slide of each chromosomally abnormal cell.
Two additional samples of blood will be drawn, the lymphocytes cultured
and scored, for each student in the study during the first school year. The
second sample should be drawn shortly after the Christmas-New Year break, and
the third sample taken before the end of the school year.
-------
-16-
Analyses will include comparisons of aberration rates in the Los Angeles
resident students and non Los Angeles resident students at each of the three
sample times. In addition, temporal analysis of the proportion and types of
abnormal chromosomes in each subject will be determined. The same study will
be repeated in these students during their sophomore and junior years.
To develop sensible short-term air quality standards, it is necessary
to have firm knowledge of human response to acute exposures to unusually high
levels of ambient air pollution. Such knowledge would be adequate to answer
the following questions for each major pollutant or class of pollutants:
(1) Does the pollutant exert effects at concentrations down to zero, or is
there a threshold which the pollution concentration must exceed before exerting
effects?; (2) If there is a threshold concentration, what is its magnitude?;
(3) Is there a minimum duration of exposure necessary to produce effects?;
(4) If so, what is it?; and (5) Of the reported human responses to acute
pollution exposure, which are based on firm and reproducible results?
A good deal of useful knowledge has emerged from epidemiologic studies
of the effects of acute air pollution exposure. For instance, there is
evidence of increased eye irritation and coughing at ambient oxidant concen-
trations above about 200 yg/m3. Such studies usually have relied upon the
judgments of subjects, whose precision in reproducing the results may be
limited. Thus the knowledge gained from studies to date would be enhanced
and amplified by a series of epidemiologic investigations of parameters which
eliminate such judgmental decisions by the subject.
A study currently underway in the Los Angeles area was designed to
minimize the possibility of subjectivity. This study examines four population
groups which may represent a spectrum of vulnerability to acute oxidant
exposures. At one end of the spectrum are trained runners, who may be most
-------
-17-
resistant to adverse effects, but who may show physiologic or biochemical
impairments when physically stressed. At the other end of the spectrum are
documented asthmatics and chronic bronchitis patients, who may be most
sensitive to changes in air pollution levels. Between these extremes are
healthy outdoor workers who, because of their unusually constant outdoor
exposures, may reflect acute pollution effects more readily than other healthy
segments of the population.
Health data have been collected before, during, and after acute exposures
to unusually high ambient air pollution levels. Specific items of health
data are electrocardiograms, blood pressure, heart rate, total white cell
counts, differential white cell counts (including eosinophils), blood levels
of immunoglobulins, and pulmonary function tests. These tests included closing
volume determinations and volume-vs.-time tracings of the entire forced vital
capacity maneuver. From such tracings, the FVC, the FEV, the maximal mid-
expiratory flow rate (MMEF), the maximal expiratory flow rate (MEFR), and
flow-volume loops can all be extracted.
From the outdoor workers and asthmatics, measurements of pulmonary function
were obtained on successive days during the season of highest pollution exposure.
Aerometric data, collected continuously throughout the period of study,
are available for each study community. For all four groups under study,
complete and accurate information has been collected on additional variables
such as age, height, sex, race, smoking habits, socioeconomic status, and
occupational exposure to respiratory irritants, which may affect the investi-
gated parameters.
Finally, Los Angeles will be one of several major metropolitan areas in
which studies of daily mortality in relation to pollutant exposures are being
initiated.
-------
Toxicology
lexicological studies have revealed a multitude of pulmonary effects
resulting from inhalation of ozone, such as pulmonary edema (Alpert, &t al.,
1971), proliferation of fibrous tissue (Freeman, et at., 1974), swelling and
disruption of pulmonary endothelium (Bils, 1970), changes in pulmonary function
(Bates, et al., 1972), impairment of pulmonary defense mechanisms (Coffin, et
al., 1968 and Alpert, et al., 1971), and increased susceptibility to infection
(Coffin and Gardner, 1972).
It was formerly believed that the action of ozone upon the respiratory
tract was accompanied by the destruction or neutralization of the ozone and
for this reason was not absorbed into the body. Nevertheless, evidence is
accumulating that ozone exposure can also produce non-pulmonary effects, such
as sphering of RBC (Brinkman, et al., 1964), lymphocyte chromosome aberrations
(Zelac, et al., 1971), lipid peroxidation of RBC (Goldstein and Balchum, 1967),
and slowed desaturation of oxyhemoglobin (Brinkman and Lamberts, 1958). How-
ever, all of these effects could have been produced by the action of ozone on
these cells during passage through the pulmonary capillaries and hence may not
be a result of ozone acting at some distant site. Still, others report extra-
pulmonary effects which cause structural changes in parathyroid gland (Atwal
and Wilson, 1974), and in heart muscle as well as increased neonatal mortality
(Brinkman, et al., 1964).
In a recent study conducted in Dr. David Coffin's laboratory, rats were
used to assess the influence of ozone on drug metabolism. The rats were
exposed three hours daily, for periods up to seven days, to 1963 yg/m3 of
ozone or clean air. Groups of ozone exposed or control animals were removed
from the chambers each day and injected with 50 mg/kg of pentobarbital
sodium. Following the injection, two effects were measured: 1) induction
time - the time interval between injection of pentobarbital and the loss of
-------
-19-
righting reflex (when the mouse remained on its back after placed there),
and 2) sleeping time - the length of time elapsed between the loss and
regaining o'f the righting reflex.
The induction time following pentobarbital injection was not influenced
by ozone exposure. There was a significant increase in sleeping time
associated with prior exposure to ozone. The difference was manifested con-
sistantly (p < .05) when pentobarbital sodium anesthesia followed the second
and third ozone exposure. Following injection, the observed sleeping time
increase was 13 minutes after the second day of ozone exposure and was 9.2
minutes after the third day of ozone exposure. No statistically significant
difference in average sleeping time between control and ozone exposed mice
was detected following a single exposure or after four or more successive
daily exposures. '
In considering mechanisms underlying this altered response to pento-
barbital, there seems to be little doubt in the literature that the duration
of the sleeping time induced by the barbituate is primarily correlated to
biotransformation of the drug in the liver (Freudenthal and Carroll, 1973).
Ozone could interfere with the biosynthesis or function of the hepatic
microsomal oxygenases metabolizing pentobarbital. The properties of the
lung and liver oxygenases are similar (Bend, et al., 1972). Palmer, et al. ,
1971, found that a single ozone exposure as low as 1500 yg/m3 for three hours
reduced the activity of lung microsomal enzymes. No effect was observed
on the liver oxygenases immediately after ozone exposure. Since two ozone
exposures were necessary before a measurable increase occurred in the sleeping
time, a decline in hepatic oxygenases might not be observed until after
repeated ozone exposure. Such a delay in the loss of the oxygenase could
be due either to direct inactivation or to inhibition of biosynthesis.
-------
-20-
It is interesting to speculate on the biological consequences resulting
from ozone interaction with lunq tissue which could produce a physiological
effect at a distant target organ. Although it is not likely that ozone
itself could reach the microsomal enzymes of the liver and directly alter
their activity, an active ozone-induced intermediate might be produced which
is then transported through the circulation. Ozone exposure has been shown
to give rise to a number of possible damaging reactions within the pulmonary
tissue, viz., peroxidation of unsaturated lipids (Chow and Tappel, 1972),
and oxidation loss of sulfhydryls (Stokinger, 1965; Menzel, 1970). Micro-
somal oxygenases are inhibited by lipid peroxidation (McCay, et al. , 1971
and 1972). Menzel and his colleagues (1972) have demonstrated that certain
partially oxidized species, such as fatty acid ozonides, could be responsible
for the systemic effects by peroxidation of hepatic membranes. Although
such reactive products have a pulmonary origin, it is plausible that they may
interfere with normal function of enzymes elsewhere in the body. A systemic
effect via these reactive products could also explain the protective effects
of alpha-tocopheral (vitamin E) (Menzel, et al. , 1972).
Studies are now underway to demonstrate more definitively some of the
mechanisms discussed. This work includes direct measurement of hepatic
oxygenases and cytochrome P-450 activities after ozone exposure, blood barbi-
tuate levels in pre-exposed and control animals, and sleeping time after
barbital, a barbituate not metabolized, but excreted unchanged by the kidney.
In summary, the current EPA program is providing data which confirm
results of studies upon which the current standard is based and, in addition,
give evidence of effects not previously described in humans. There is no
new evidence to support a relaxation of the current photochemical oxidant
standard. On the contrary, new research results are suggesting the current
standard may not include a safety margin as adequate as previously believed.
-------
PROTOCOL
Experimental Myocardial Infarction
12 Mongrel Dogs
MEASUREMENTS
1. Epicardial EKG
2LJrt-jy»+ P ~\ 4- f\
• ntco I \f r\G uc
3. LA Press.
4. AO. Press.
5. Cardiac Output
6. Ejection Time
7. COHB deter.
-CORONARY OCCLUSION'
1
-BASELINE-60 min POST INFARCTION
-CO INTERVENTIONS-
t
-A
t
-B-
t
-C
y
MEASUREMENT
Myocardial
Blood Flow
(radioactive
microspheres)
-------
RIGHT ATRIUM
AORTIC ROOT
PRESSURE
RIGHT CORONARY
ARTERY
LEFT ATRIAL
CATHETER -
PRESSURE
AND
MICROSPHERE
INJECTIONS
CIRCUMFLEX ARTERY
LEFT DESCENDING
CORONARY ARTERY
LIGATEDBRA N C H E S
LAD
MAPPING SITES
-------
LEFT VENTRICULAR FREE WALL OPENED FLAT
ANTERIOR / POSTERIOR
ORIGIN OF LAD
LIGATED BRANCHES
OF LAD
INFARCTION AREA
BRANCHES OF CIRCUMFLEX
POINTS FOR EPICARDIAL EKG MAPPING
-------
% COHb
BASELINE INTERVENTION
A B C D E
mean* <.5 4.78 8.42 11.26 14.20 17.27
s.d. ±0.79 ±1.48 ±1.66 ±2.05 ±2.64
* Excludes dogs 8, 9, 10
-------
£ ST Elevation
(10 millimeter/millivolt)
DOG #
1
2
3
4
5
6
7
11
12
mean
s.d.
DOG #
8
DOG #
9
10
BASELINE
19
52
47
8.5
6
62
50
55
10.5
34.4
±22.9
8.5
0
0
A
30.5
50.5
57
10.5
8.5
82.5
54
58.5
16
40.9
±25
18.5
No
0
0
B
25
53.
52
10
9.
89.
70
64.
27.
44.
.7 ±2
H.R. t
24.
Baseline
0
13
INTERVENTION
C
32.5
5 70.5
55
10.5
5 16
5 94
85.5
5 80
5 39.5
6 58.7
8.1 ±30.7
40%
5 30.5
Infarction
3
29
D
34
69
51.5
9
15
94.5
84
78
38.5
52.6
±30.7
49
15
34
E
34
81
62.5
13.5
20.5
103.5
75
78
35.5
55.9
±31.1
65.5
20.5
38.5
-------
COMPARISON OF MODEL AND OBSERVED VALUES
OF % INCREASE IN 2 ST VS. % COHb !
I I I I
Mi
100
90
80
70
60
UJ
cc
o
5 50
a?
40
30
20
10
0
MODEL
2 ST = 3.7 (%COHb)
p S .001
95% PREDICTION
INTERVALS!
I r i i i
2468 10 121 14: 16 18 20! 22 24 26
%COHb
-------
Left Ventricular Radioactive
Microsphere Flow Data
(mean flow in cc/ g/min)
AREA
Ischeroic
Full Thickness
Inner Half
Outer Half
BASELINE
(<1X COHb)
0.30 ± 0.14
0.19 ± 0.10
0.40 ± 0.19
INTERVENTION
B (8.4% COHb) E (17.3% COHb)
0.29 ± 0.13
0.19 ± 0.11
0.39 ± 0.19
0.25 ± 0.03
0.16 ± 0.03
0.34 ± 0.13
Non-Ischemic
Full Thickness
Inner Half
Outer Half
1.01 ± 0.41
0.98 ± 0.36
1.04 ± 0.47
1.12 ± 0.55
1.13 ± 0.47
1.22 ± 0.66
1.30 ± 0.60
1.24 ± 0.50
1.37 ± 0.72
Excludes dog 112
-------
% INCREASE IN BLOOD FLOW TO
NON-ISCHEMIC AREA VS. % COHb
Si
30
20
10
NON-ISCHEMIC
FLOW
8 10
%COHb
12
14
16
18
-------
B. DR RICHARD STEWART
CARBONXYHEMOGLOBIN TREENDS IN
CHICAGO BLOOD DONORS
-------
Presentation at E.P.A. Scientific Seminar on Automotive Pollutants. February 10, 1975
CARBOXYHEMOGLOBIN TREND IN CHICAGO BLOOD DONORS, 1970-1975
By: Richard D. Stewart, MD, MPH; Carl L. Hake, PhD;
Anthony J. Wu, PhD; and John H. Kalbfleisch, PhD
From the Department of Environmental Medicine, The Medical College of Wisconsin, Allen
Bradley Medical Science Laboratory, Milwaukee.
A national survey was conducted in 1969-1972 to determine the range of
carboxyhemoglobin (COHb) in 29,000 blood donors living in urban, surburban, and rural
communities across the United States, including Alaska and Hawaii (1,2, Appendix A).
The COHb measurement had been shown to be an accurate measurement of the average or
time-weighted carbon monoxide (CO) exposure occurring in the previous 15-hour interval
(3-5)and it was anticipated that this use of man as his personal CO monitor would
supply valuable air pollution data from areas where a system of air monitoring stations
had not yet been deployed. It was further anticipated that these COHb measurements
would permit comparison of the magnitude of the CO exposure in one area with that of
another, and that future COHb measurements in non-smokers could be used to monitor the
effectiveness of anti-pollution programs developed and employed by this nation.
Chicago blood donors were sampled in November, 1970, and 74% of the 406
non-smoking blood donors tested had COHb levels at greater than 1.5% which indicated
that exposure to CO in excess of that permitted by the Clean Air Acts Quality Standards
of 1971 was widespread and occurring regularly. Of the areas surveyed, only Los
Angeles and Denver had a higher percentage of blood donors with COHb levels greater
than 1.5%
This report presents the COHb data of the recently conducted survey of
blood donors in the Chicago area sampled in December, 1974, and January, 1975. The
data analysis is necessarily preliminary in that the correlation with the weather
conditions and the reported atmospheric CO levels has not been completed. It is
anticipated that the final data analysis will have been finished within the next
sixty days.
-------
Stewart - page 2
EXPERIMENTAL PROCEDURE
Two research associates trained in interviewing techniques collected
blood samples from Chicago donors at arbitrarily chosen mobile unit collection sites
during December 1974 and for one week in January 1975. At the time of blood collec-
tion questionnaires were completed so that influence of the following variables
could be assessed: age, weight, height, sex, race, smoking habits, place of residence,
occupation, location and time of blood sampling, and meteorological conditions.
The venous blood samples were collected in 5 ml. tubes containing EDTA
as the anticoagulant. The samples were then mailed to The Department of Environ-
mental Medicine Laboratory, Milwaukee, for analysis. The blood samples were
analyzed on two Co-Oximeters (Instrumentation Laboratories) which had been calibrated
by the gas chromatographic procedure based on the method of Collison (6-7). The
preparation of the COHb standards and the calibration procedure has been previously
reported (1-2).
RESULTS
Table 1 presents the COHb levels of the Chicago blood donors determined
in the 1974-75 survey and compares these with COHb levels reported in 1970. It is
immediately apparent that tobacco smoking was associated with a COHb saturation con-
siderably higher than observed in the non-smokers. Of greatest interest is the
observation that the median COHb value in the non-smokers had dropped from 1.8%
observed in 1970 to 1.4% in 1974-75. This change in the COHb distribution for non-
smokers is illustrated in Figure 1.
In Table 2, the median COHb saturation and the 90% range for the blood
donors in the thirteen Chicago collection locations is shown.
In Figure 2, the COHb distribution for tobacco smokers for the two periods
of observation is shown. Each curve represents a conglomerate of tobacco smoking
-------
Stewart - page 3
types and as such does not permit a statement as to whether a difference in COHb
levels in smokers between the two periods is discernable.
In Figures 3, 4, and 5, the median and 90% COHb range for blood donors
in the north shoreline area, northwest suburbs, and downtown locations are presented
for the two periods of observation.
COMMENT
The most relative finding of this recent Chicago study was the observation
that the median COHb saturation in non-smoking blood donors had significantly de-
creased between 1970 and 1974. This would indicate that the antipollution measures
currently being employed were having a definite effect on the quality of air in the
Chicago area.
This comparative study illustrates the feasibility of using the COHb data
generated in the initial 1969-1972 national survey as a data base with vhich to
determine air pollution trends in the United States.
-------
Stewart - page 4
TABLE I
BLOOD DONOR COHb LEVELS IN CHICAGO IN 1970 AND 1974-75
Non-Smokers Tobacco Smokers
1970 1974-75 1970 1974-75
Number
Sample Median
Sample Mean
90% Range
406
1.8
2.04
1.1-3.2
431
1.4
1.53
.7-2.4
440
5.8
5.80
1.8-9.9
342
5.2
5.56
1.3-8.9
-------
TABLE 2
CHICAGO 1974-75
LOCATION
122 S. Michigan, Chicago
6525 N. Sheridan, Chicago
5333 S. Laramie, Chicago
11220 S. Wallace, Chicago
One First National Plaza
Chicago
700 N.W. Highway
Des Plaines
2775 Saunders Rd
Northbrook
7135 S. Hamlin, Chicago
83rd Place & St. Louis
4901 Searle Parkway
Skokie
3600 S. 57th Court, Cicero
11426 S. Avon
Alsip
140 S. State
N
87
22
4
17
96
8
29
33
34
34
28
1
28
MEAN
1.77
1.4
1.53
.81
1.49
.99
1.18
1.67
1.62
1.72
1.20
1.81
NON-SMOKERS
MEDIAN RANGE (*)
1.6
1.4
1.55
.80
1.45
.95
1.10
1.60
1.65
1.50
1.10
3.0
1.80
.8
1.1
1.2
.5
.7
.6
.6
1.2
1.1
1.0
.7
1.2
to 3.6
to 1.9
to 1.8
to 1.2
to 2.4
to 1.4
to 2.2
to 2.4
to 2.2
to 3.8
to 2.1
to 2.8
N
58
12
9
11
90
13
18
18
18
18
21
6
35
TOBACCO SMOKERS
MEAN MEDIAN
5.15
3.73
4.48
3.87
4.71
4.75
4.61
6.18
5.59
5.24
5.34
6.00
6.54
5.2
3.60
4.20
3.20
5.05
4.40
4.05
6.30
4.80
5.20
5.05
8.35
6.30
en
rt
a
p
it
RANGE (*) n
1.8
1.4
2.1
.8
1.0
1.3
1.7
1.4
1.1
1.4
2.1
.8
3.9
to
to
to
to
to
to
to
to
to
to
to
to
to
1
8.4 "S
oo
a>
6.2 ui
7.2
12.1
8.4
7.6
10.2
10.8
11.8
8.2
10.1
9.6
10.0
(*) 90% Range if N » 30
100% Range if N «C 30
-------
Stewart - page 6
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-------
Stewart - page 7
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-------
Stewart - page 8
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-------
Stewart - page 9
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-------
Stewart - page 10
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-------
Stewart - page 11
REFERENCES
1. Stewart, R. D., et al: "Normal" Carboxyhemoglobin Levels of Blood Donors
in the United States, NTIS report No. PB222503. Springfield, Va., National
Clearinghouse for Federal Scientific and Technical Information.
2. Stewart, R. D., Baretta, E. D., Platte, L. R., et al: Carboxyhemoglobin
Levels in American Blood Donors. JAMA 229;1187-1195, August, 1974.
3. Forbes, W. H., Sargent, F., Roughton, F. J. W.: The rate of carbon monoxide
uptake by normal men. Am. J. Physiol. 143;594-608, 1945.
4. Stewart, R. D., et al: Experimental human exposure to carbon monoxide.
Arch. Environ. Health 21;154-164, 1970.
5. Peterson, J. E., Stewart, R. D.: Absorption and elimination of carbon
monoxide by inactive young men. Arch. Environ. Health 21:165-171, 1970.
6. Collison, H. A., Rodkey, F. L., O'Neal, J. D.: Determination of carbon
monoxide in blood by gas chromatography. Clin. Chem. 14:162-171, 1968.
7. Dodd, H. C., et al: Analysis of Carboxyhemoglobin with a Helium-Ionization
Detector. Report No. ENVIR-MED-MCW-CRC-COHb-73-3, to be published.
-------
Reprinted from the Journal of the American Medical Association
August 26, 1974 Volume 229
Copyright 1974, American Medical Association
APPENDIX A
Carboxyhemoglobin Levels
in American Blood Donors
Richard D. Stewart, MD, MPH; Edward D. Baretta, MS;
Leigh R. Platte, MT (ASCP); Elizabeth B. Stewart, MT (ASCP);
John H. Kalbfleisch, PhD; Barbara Van Yserloo; Alfred A. Rimm, PhD
• A national survey was conducted In 1969-1972 tor the purpose of deter-
mining the range of carboxyhemoglobln (COHb) levels In various segments
of the American population. Venous blood samples for COHb analysis were
obtained from 29,000 blood donors living In urban, suburban, and rural com-
munities across the United States. For comparative purposes, COHb mea-
surements were made on samples obtained from 11 volunteers breathing air
free of carbon monoxide (CO) or air with known concentrations of CO. The
mean COHb saturation of four adults breathing CO-free air was 0.45%. Forty-
five percent of all the nonsmoking blood donors tested had COHb satura-
tions of more than 1.5%. This Indicated that exposure to CO In excess of that
permitted by the Air Quality Standards was widespread and occurring regu-
larly. Tobacco smoking was the single most Important factor responsible for
the highest COHb saturations observed. The other chief factors Influencing
the COHb saturation were the geographical location of the Individual, occu-
pation, and the existing meteorological conditions.
(JAMA 229:1187-1195, 1974)
CARBON MONOXIDE (CO) is one of
the major air pollutants that has the
potential for adversely affecting hu-
man health. To protect the public, the
Clean Air Act's Quality Standards of
1971 limit CO exposure. Compliance
with the eight-hour standard pre-
vents excursion, of blood carboxyhe-
moglobin (COHb) of more than 1.5%
saturation in active nonsmokers.
Assuming that the Air Quality
Standards for CO are scientifically
From the Department of Environmental Medi-
cine, the Medical College of Wisconsin, Allen
Bradley Medical Science Laboratory, Mil-
waukee.
Reprint requests to Allen Bradley Laboratory,
8700 W Wisconsin Ave, Milwaukee, Wl 53226
(Dr. Stewart).
valid and that exposure to CO concen-
trations in excess of the standard
could be detrimental to human health,
the immediate questions are "Does
overexposure to CO occur in any seg-
ment of our population?" and "Are
the major metropolitan areas in the
United States currently able to com-
ply with the CO standards?"
The major difficulty in answering
these questions is the horrendous task
of analyzing the CO in the breathing
zone of each individual placed under
surveillance by the Air Quality Stan-
dards. Few cities have air monitor-
ing systems able to estimate the CO
exposure of their inhabitants, and
even those few systems obtain esti-
mates that are incapable of denning
individual exposures. For example, a
Los Angeles monitoring station lo-
cated 12 meters above an expressway
cannot measure the concentration of
CO eight blocks away in the breath-
ing zone of a policeman directing
traffic at a busy intersection, nor that
of a clerk on the 20th floor of an office
building adjacent to the intersection.
Therefore, the precise CO exposure
that various segments of the popu-
lation experience is not known and
can only be estimated from air-moni-
toring-station data.
Since the inspired CO is absorbed
through the lungs and circulates in
the blood as COHb, the measurement
of the COHb concentration has been
shown to be an accurate measure-
ment of the mean CO exposure occur-
ring in the previous 15-hour interval.
This COHb measurement provides a
more accurate means for determining
the magnitude of recent CO exposure
than currently is possible with the
limited number of monitoring sta-
tions.1-3
This investigation was undertaken
to determine the range of COHb in
blood donors living in urban, subur-
ban, and rural communities across the
United States. Venous blood samples
were obtained from 29,000 donors and
were analyzed for COHb. For com-
parative purposes, COHb measure-
ments were made on blood samples
from 11 volunteers breathing CO-free
JAMA, Aug 26, 1974 • Vol 229, No 9
Carboxyhemoglobin Levels—Stewart et al 1187
-------
air or air with known concentrations
of CO.
Experimental Procedure
Two research associates trained in
interviewing techniques journeyed
across the United States from April
1969 through June 1972 collecting
blood samples from donors at arbi-
trarily chosen blood-bank collection
sites. At the time of blood collection,
detailed questionnaires were com-
pleted so that the influence of the fol-
lowing variables could be assessed:
age, weight, height, sex, race, smok-
ing habits, place of residence, occupa-
tion, place of work, location and time
of sampling, meteorological condi-
tions, and background CO concentra-
tion at sampling site. From every
tenth participant, an alveolar breath
sample was obtained for CO analysis.
The sample served as an independent
check on the stability of the COHb
until time of analysis.4'11
The venous blood samples were col-
lected in 5-ml tubes containing edetic
acid as the anticoagulant and alveolar
breath samples were collected in 35-
ml glass pipettes.'1 The samples were
then air-mailed to the Department of
Environmental Medicine Laboratory,
Milwaukee, for analysis. Blood sam-
ples were analyzed by the automated
differential spectrophotometric proce-
dure based on the method of Malen-
fant"'7 and by gas chromatographic
procedure based on the method of Col-
lison.*'8 Two carboxyhemoglobin cali-
bration standards, < 1% and > 4%,
were used each morning and period-
ically throughout the analytical day
to recheck the calibration of the two
spectrophotometers used.10'" The
preparation of these COHb standards
has been previously reported in de-
tail." Breath samples were analyzed
by gas chromatography by the
method of Porter and Volman.12
To determine the stability of the
COHb moiety in the venous blood
samples, tubes of blood were stored at
22 C and 4.5 C, and then the samples
were sequentially analyzed for COHb
content.
Each blood sample for COHb deter-
mination was analyzed on a properly
calibrated differential spectropho-
tometer. In addition, each tenth
sample was analyzed on a second in-
7.0
O
O
E
a
a
T3
a
a
JC
^c
O
O
30 60 90 120 150 180
Minutes of Exposure
210 240 270
Fig 1.—Actual carboxyhemoglobin (COHb) saturation of seven subjects exposed to
fluctuating carbon monoxide (CO) concentrations in the controlled-environment
chamber compared with the theoretical values calculated by using the CFK equation '
strument. If the results of the two
analyses varied by more than 0.2%
saturation, the instruments' calibra-
tion was rechecked and the difficulty
corrected. The final ten blood samples
analyzed each day were stored at 4.5
C and analyzed the next day as an ad-
ditional calibration check.
To check on the ability of the two
COHb analytical methods to measure
accurately low concentrations of
COHb, four adults (three men and
one woman) breathed 100% oxygen
delivered through an oxygen face
mask for a period of 3"^ hours, fol-
lowing which they breathed air for
90 minutes that had been passed
through a filter to remove CO. Venous
blood samples were obtained every 30
minutes for COHb analysis by the
two methods described previously.
To check on the ability of the two
COHb analytical methods to measure
accurately COHb saturation from
1.0% to 6.0%, seven volunteers were
exposed to fluctuating CO concentra-
tions in the controlled-environment
chamber.13
To determine the precision with
which the breath samples were col-
lected, duplicate samples were ob-
tained from every 20th subject in Los
Angeles.
In the analysis of the data, the me-
dian and 90% ranges were used to de-
scribe the distribution of COHb satu-
ration in the various geographical
locations. Mean COHb saturation was
used to investigate the effect of the
other variables such as smoking and
occupation. The statistical methods
used to assess the observed differ-
ences between mean COHb satura-
tions were the t test and analysis of
variance for two or more means. Mul-
tiple regression techniques were used
to investigate the influence of me-
teorological variables on mean COHb
saturation. In all cases, a significance
level of P<.01 was used to declare
statistical significance.
Results
The mean COHb saturation of the
four adults prior to breathing 100%
oxygen was 0.65%, with a range of
0.55% to 0.75%. After two hours of in-
haling 100% oxygen, the mean COHb
saturation was 0.36%. After 3.5 hours
of oxygen inhalation, the mean COHb
was 0.38%, with a range of 0.30% to
0.40%. After breathing CO-free air
for 90 minutes, the mean COHb satu-
ration was 0.45%, with a range of
0.35% to 0.5%. This COHb saturation
is in agreement with that reported
due to endogenous CO production,"
and it demonstrated the sensitivity of
the analytical procedures in detecting
low concentrations of COHb.
1188 JAMA, Aug 26, 1974 • Vol 229. No 9
Carboxyhemoglobin Levels—Stewart et al
-------
.c
a
a
I
n
O
I
O
O
2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34
% of COHb by Differential Spectrophotometer
Fig 2.—There is good agreement between the two analytical
methods for Carboxyhemoglobin (COHb) determination; COHb
mean and range values obtained for six determinations by each
method on eight different blood samples are plotted.
11 12 13 14 15 16 17 >17.
Hemoglobin, gm/100 ml
Fig 3.—Relationship of hemoglobin concentration to
Carboxyhemoglobin saturation suggests that the nonsmoker
living in areas with higher CO contamination can partially
compensate for this additional anoxic stress by increasing his red
blood cell mass similarly to the way In which tobacco smokers
compensate.
The seven adults exposed to fluc-
tuating concentrations of CO during
a period of four hours attained the
anticipated COHb saturation pre-
dicted by the Coburn-Forster-Kane
equation for CO uptake."'" The pre-
dicted and actual COHb values are
presented in Fig 1. This experiment
demonstrated the accuracy of the
COHb analytical methods to measure
COHb-over the range of saturations
most frequently encountered in this
study.
The studies to determine the stabil-
ity of the COHb moiety in blood
stored at 4.5 C and 22 C showed no
signs of deterioration for periods up
to six weeks in the refrigerated sam-
ples and showed stable COHb in blood
samples unrefrigerated for two
weeks.'"
When ttie quality-control procedure
described was employed, the differ-
ential spectrophotometer yielded ex-
cellent COHb analytical results. For
example, nine repeat-sampling tests
performed with the same instrument
on the same refrigerated blood
sample during a period of 16 days
gave a mean COHb of 1.2%, with a
standard error of 0.13% and a range
of 1.0% to 1.4%.
The analytical agreement between
the two COHb methods was good (Fig
Table 1.— Median,
Location
Anchorage
Chicago
Denver
Detroit
Honolulu
Houston
Los Angeles
Miami
Milwaukee
New Orleans
New York
Phoenix
St. Louis
Salt Lake City
San Francisco
Seattle
Vermont,
New Hampshire
Washington, DC
Carboxyhemoglobin
Smokers and
Cigarette
Smokars
4.7 (0.9-9.5)
5.8 (2.0-9.9)
5.5 (2.0-9.8)
5.6 (1.6-10.4)
4.9 (1.6-9.0)
3.2 (1.0-7.8)
6.2 (2.0-10.3)
5.0 (1.2-9.7)
4.2 (1.0-8.9)
5.5 (2.0-9.6)
4.8 (1.2-9.1)
4.1 (0.9-8.7)
5.1 (1.7-9.2)
5.1 (1.5-9.5)
5.4 (1 .6-9.8)
5.7 (1.7-9.6)
4.8 (1.4-9.0)
4.9 (1.2-8.4)
(COHb) Saturation
Nonsmokers
and 90%
No. of
Nonsmokers Nonsmokers
1.5 (0.6-3.2)
1.7 (1.0-3.2)
2.0 (0.9-3.7)
1.6 (0.7-2.7)
1.4 (0.7-2.5)
1.2 (0.6-3.5)
1.8 (1.0-3.0)
1.2 (0.4-3.0)
1.2 (0.5-2.5)
1.6 (1.0-3.0)
1.2 (0.6-2.5)
1 .2 (0.5-2.5)
1.4 (0.9-2.1)
1.2 (0.6-2.5)
1.5 (0.8-2.7)
1.5 (0.8-2.7)
1.2 (0.8-2.1)
1.2 (0.6-2.5)
152
401
744
1,172
503
240
2,886
398
2,720
159
2,291
147
671
544
660
585
959
850
Range for
%of
Nonsmokars
With COHb
>13%
56
74
76
42
39
30
76
33
26
59
35
24
35
27
61
55
18
35
2) and the two diiferential spectrc-
photometers gave an average abso-
lute difference of 0.20% COHb be-
tween samples.
The agreement between the alveo-
lar breath CO and the matched blood
COHb collected in the field did not ap-
proach the accuracy of the relation-
ship previously obtained experimen-
tally,5 but the agreement was good
enough to validate the stability of the
COHb moiety until time of analysis.11
The median COHb saturation and
the 90% range for the blood donors in
the 18 locations are listed in Table 1.
It was immediately apparent that to-
bacco smoking was associated with a
COHb saturation of an order of mag-
JAMA, Aug 26, 1974 • Vol 229, No 9
Carboxyhemoglobin Levels—Stewart et al 1189
-------
Table 2. — Median Carboxyhemoglobin (COHb) Saturation and 90% COHb Range at Various Locations
Area
Anchorage, Alaska (sampled
August, September, October 1971)
Blood center
Holy Cross
Sleetmute
Nikolai
Chicago (sampled November 1970)
Loyola University,
Lakeshore Campus
Michael Reese Hospital
A. B. Dick, Nlles, III
O'Hare International Airport
Imperial Eastman, Niles, Ml
Montgomery Ward,
Downtown Chicago
Palatine, III
Denver (sampled April, May 1971)
Blood center
Boulder, Colo
Stapleton International Airport
Detroit (sampled November,
December 1970, September,
October 1971
Chrysler Corp.
G. M. Tech Center, Warren, Mich
Formoco, Dearborn, Mich
Keefer Mfg. Co.
Wyandotte
B'nal B'rlth, Oak Park, Mich
Plus Southgate
Parke, Davis & Co.
IBM
River Rouge, Mich
Warren, Mich
St. Clalr Shores, Mich
Dye and machine plant
Vpsllantl, Mich
Rochester, Mich
Downtown Detroit
Honolulu (sampled June 1971)
Queens Hospital
Blood center
Hllo, Hawaii
Houston (sampled April 1972)
Blood center
Sweeney, Tex
Unim Hall
Westbury Methodist Church
Prairie View. Tex
Hobby (airport)
La Porte, Tex
Huntsvllle, Tex
Downtown Houston
Jersey Acres, Tex
Texas City
K-mart, South Houston
Los Angeles (sampled January,
February, May, June 1972)
Burbank, Calif
Torrance, Calif
Long Beach, Calif
El Segundo, Calif
Hollywood. Calif
Van Nuys, Calif
No. of
Donors
103
14
26
8
148
41
80
32
34
30
41
676
27
42
23
341
83
20
55
59
64
47
25
42
74
17
86
101
82
57
175
195
138
75
7
11
8
10
15
14
15
17
38
27
ID
419
58
105
172
148
361
Nonsmokers
Median
COHb
Saturation
1.7
1.5
1.0
0.7
1.5
2.1
1.7
2.5
2.0
2.7
1.4
2.0
1.2
1 5
2.1
1.4
2.0
1.0
1.5
1.5
1.4
1.2
1.4
1.4
1.6
1.0
1.4
0.9
1.2
1.2
1.2
1.4
1.4
1.2
0.9
1.4
2.2
1.4
0.9
0.8
0.7
1.2
1.2
1.4
ID
1.8
1.9
1.6
1.8
2.2
1.8
Cigarette Smokers
90%
COHb
Range
0.9-2.8
0.4-2.2
0.6-8.2
0.5-1.4
1 .0-2.2
1.0-2.2
1 .2-2.7
1 .8-3.0
1 .5-2.7
2.2-3.7
0.8-4.4
1.0-3.7
0.6-2.1
0.8-2.5
1 .2-3.6
0.8-2.2
1.0-3.7
0.6-1.6
0.9-4.6
0.8-2.7
0.7-3.6
0.4-2.0
0.7-2.3
0.6-3.6
0.9-2.7
0.9-3.0
0.6-2.5
0.6-1.2
0.8-2.3
1.0-1.8
0.6-2.5
1 .0-2.7
0.7-2.0
0.6-2.8
0.8-2.7
1.0-2.7
ID
1.0-3.4
1.5-2.3
1 .2-5.4
1 .2-2.5
1.4-3.0
1.0-2.7
No. of
Donors
81
24
12
30
83
163
81
16
47
34
16
884
13
16
40
145
61
30
40
17
34
28
17
31
40
38
70
41
58
33
160
227
134
4
IDf
1
1
4
2
^
i
1
1
2
- 8
295
46
59
66
130
208
Median
COHb
, Saturation
5.9
2.3
4.8
2.5
3.6
5.9
6.1
6.6
6.8
6.9
4.8
5.5
4.5
5.8
6.3
5.8
7.2
6.4
6.4
5.9
6.5
5.1
5.6
6.0
6.2
6.1
6.0
3.5
5.9
6.0
4.7
5.4
4.9
2.6
ID
7.4
8.2
2.0
4.0
4.4
0.7
2.1
7.8
5.5
13.4
6.5
6.8
5.2
5.9
6.2
6.8
90%
COHb
Range
0.9-9.9
0.9-6.3
1.2-70
1.0-47
1 2-7.8
2.3-9.9
2.5-9.6
5.2-11.1
3.2-104
3.2-9.3
1 .5-7.7
2.0-9.9
1.2-7.7
2.7-9.1
3.7-9.3
1 .7-9.5
27-104
4.5-10.5
3.0-10.7
2.0-9.6
2.5-10.7
7.0-8.2
2.2-10.5
1 .6-9.6
1.8-10.3
2.5-10.5
3.0-8.5
1 .2-6.1
2.0-9.4
2.3-9.0
1.6-9.0
2.0-9.6
2.0-8.2
*
ID
2.5-10.5
2.0-10.5
1.5-9.4
2.0-9.9
2.5-10.0
2.0-10.7
1190 JAMA, Aug 26, 1974 • Vol 229, No 9
Carboxyhemoglobin Levels—Stewart et al
-------
Table 2. — Median Carboxyhemoglobin (COHb) Saturation anc
i
Area
El Toro. Calif
El Monte, Calif
Blood center
Reseda, Calif
Duarte, Calif
Westvvood. Calif
Eagle Rock. Calif
Anaheim, Calif
Downtown Los Angeles
Hawthorns, Calif
Huntlngton Beach, Calif
Glendale, Calif
Airport
Century City. Calif
Miami, Fla (sampled January,
February 1971, January 1972)
Blood center
South Miami
Merchandise Mart
Downtown Miami
Airport
Milwaukee (sampled April-Decem-
ber 1969, January-December 1970,
April 1971)
Milwaukee County
General Hospital
Milwaukee Children's Hospital
Pewaukee, WIs
Milwaukee Blood Center
Allen Bradley Co.
Brookfleld, WIs
Brown Deer, WIs
Veterans Administration Hospital
Cedarburg, WIs
New Orleans (sampled February,
March 1971)
Charity Hospital
Buras, La
New York City (sampled December
1970, October, November, Decem-
ber 1971)
Isllp, Long Island
Metropolitan Life Auditorium,
Madison Ave
Long Island, NY
Bronx, NY
Manhattan, NY
J. F. Kennedy International Airport
Brooklyn, NY
Hlghtstown, NJ
Governor's Island, NY
East Blood Center
Elizabeth. NJ
'Holmdel.NJ
East View. NY
Croton, NY
New Jersey
Phoenix, Ariz (sampled March 1972)
Blood center
Mt Calvary Lutheran Chucrh
Angel's Lumber Co.
St. Louis (sampled March 1971)
St. Genevleve. Mo
Mary Magdalen Church
Brentwood, Mo
No. of
Donors
31
119
15
28
51
127
117
525
166
72
72
61
213
30
185
37
21
40
17
1,831
193
120
209
102
72
92
5
121
142
16
116
64
440
75
841
38
8
46
38
21
82
146
54
197
130
145
2
0
69
119
Nonsmokars
Median
COHb
Saturation
1.8
2.0
2.7
1.8
1.7
2.0
2.0
1.7
2.7
2.2
1.6
1.7
1.4
1.4
1.2
1.0
1.4
1.0
0.9-
1.2
1.0
1.0
1.4
1.4
0.8
1.4
0.7
1.0
1.6
1.4
1.4
1.2
1.0
1.4
1.4
2.1
2.1
1.2
0.8
2.0
1.5
1.0
1.4
1.0
1.2
1.2
0.8
1.2
1.6
90% COHb Range at Various
Locations (Continued)
Cigarette Smokers
90%
COHb
Rang*
1 .5-6.9
1.2-3.2
1.5-2.2
1.5-4.5
1 .2-2.8
1.5-2.5
0.6-2.3
1 .0-3.2
1 .7-2.7
1 .2-2.3
1 .4-2.0
1.0-2.1
1.0-1.8
0.4-6.9
0.5-3.2
0.8-1.6
0.4-2.3
0.4-3.4
0.5-2.5
0.6-2.5
0.4-3.0
0.6-2.7
0.4-3.2
0.6-3.5
0.5-2.1
1.0-3.0
0.9-2.3
0.5-2.2
0.5-3.4
0.8-2.0
0.8-2.3
1 .5-2.8
0.8-1 .7
0.4-1 .4
1 .0-2.7
0.5-3.5
0.6-1.6
0.9-2.0
0.4-3.7
0.4-2.0
0.5-2.5
0.9-2.5
1.2-2.2
No. of
Donors
62
108
13
8
39
62
16
212
108
39
37
27
75
21
559
104
14
40
14
1,117
2
61
180
72
31
59
2
68
324
22
68
63
215
75
813
46
16
31
45
24
67
20
69
113
130
142
8
8
19
77
Median
COHb
Saturation
5.3
5.9
7.5
6.2
6.3
6.3
4.3
6.4
6.0
7.0
6.1
6.1
5.6
6.3
5.2
3.9
7.3
4.1
5.5
3.7
1.2
5.3
5.3
5.2
5.8
7.0
6.9
5.5
5.3
5.9
3.9
4.3
3.5
4.7
5.2
6.9
7.3
4.4
2.8
5.4
4.6
5.1
5.8
4.1
4.9
4.0
5.4
3.7
5.4
5.3
90%
COHb
Range
1 .5-7 8
2.5-10.2
3.4-9.4
2.2-10.7
3.2-9.7
2.0-9.4
2.5-8.7
2.0-9.0
2.0-9.1
1 .2-9.6
2.0-8.3
1 .0-1 1 .2
1.2-8.1
0.9-8.6
0.8-9.1
0.9-8 6
1 .0-1 1 .9
1 .2-9.3
0.9-9.5
1 .4-9.8
1 .0-9.5
2.0-9.2
2.8-9.6
1 .4-7.2
1 .0-7.6
1 .0-8.8
1 .6-7.6
1 .4-9.2
2.3-10.9
1.4-10.4
0.7-4.7
1.8-7.0
1 .2-7.6
1.6-8.3
2.1-8.6
1.2-8.1
1 4-8.5
1 .0-8.3
2.0-8.6
JAMA, Aug 26, 1974 • Vol 229, No 9
(Continued on p 1192.)
Carboxyhemoglobin Levels—Stewart et al 1191
-------
Table 2. — Median Carboxyhemoglobin (COHb) Saturation and
Area
St. Gabriel Church
Crave Coeur, Mo
St. Louis County
Aeronautical Chart Information
Center
St. Andrews Church, LeMay, Mo
Blood center
Webster Grove, Mo
Soldier's Field, Mo
Lambert Field (airport)
Salt Lake City (sampled February,
March 1972)
Price, Utah
Helper, Utah
Draper, Utah
Salt Lake City
Montlcello, Utah
Blanding, Utah
Moab, Utah
Castledale, Utah
Tooele. Utah
San Francisco (sampled June, July
1971)
Blood center, San Juan
Downtown San Francisco
Hunter's Point, Calif
Nob Hill, San Francisco
Seattle (sampled July, August 1971)
Boeing Plant 2
Bremerton ship yards
Blood center
Downtown Seattle
Seattle Pacific Colleoe
Kirkland, Wash
South Seattle
Auburn, Wash
Prince of Peace Church
Seattle Airport
South Blood Center
Vermont-New Hampshire
(sampled November 1971)
Lyndonvllle, Vt.
Hanover, NH
Portsmouth, NH
Rlchford, Vt
Littleton, NH
Berlin, NH
Derbyllne, Vt
Rutland, Vt
Arlington, Vt
Brattleboro, Vt
Northfleld. Vt
Montpelier, Vt
Whlterlver Junction, Vt
Washington, DC (sampled January
1971)
Blood center
Maryland
Veterans Administration Hospital
Georgetown University
Sears, Roebuck & Co, V Street
No. of
Donors
135
52
29
44
27
20
23
72
83
40
50
74
139
53
61
33
23
72
461
119
33
49
29
6
339
85
11
5
7
42
12
43
6
23
395
58
28
44
39
13
40
54
90
59
52
64
54
394
358
27
20
Nonsmokers
Median
COHb
Saturation
.2
.2
.2
.2
.2
1.6
1.4
1.4
1.5
1.7
1.4
1.4
1.2
0.9
1.0
0.9
0.8
1.0
1.5
1.8
1.8
1.5
1.5
1.4
1.5
1.6
1.2
1.2
1.5
1.4
1.2
1.4
1.0
1.2
1.2
1.2
1.5
1.4
1.4
1.5
1.0
1.2
1.4
1.2
1.2
1.2
1.5
1.2
1.0
1.2
2.1
90% COHb Range at Various Locations (Continued)
Cigarette Smokers
A
90%
COHb
Range
0.7-1.7
0.8-1 .7
0.9-1.6
0.7-1.7
0.7-2.2
1 .2-2.2
1 .0-1 .5
1.0-2.0
0.6-2.2
1.4-2.0
0.8-2.3
0.8-4.4
0.7-2.0
0.5-1.7
0.6-1.4
0.5-2.2
0.4-3.9
0.5-2.5
0.7-2.7
1.2-2.7
1 .2-2.7
1 .0-2.5
1.2-2.4
0.8-2.7
1 .0-2.3
0.5-4.2
0.8-2.2
0.9-1 .8
0.4-2.5
0.8-2.7
1.0-2.1
0.9-3.7
1.0-2.3
0.6-1.5
0.7-3.7
1.0-3.0
1 .0-4.6
0.9-1.8
1.0-1.8
0.7-2.5
0.7-2.8
0.5-2.2
0.8-1.5
1.4-2.8
No. of
Donors
69
21
30
16
6
8
8
38
53
12
22
0
40
6
4
17
1
50
301
60
29
48
24
19
193
49
2
7
6
27
5
27
2
14
83
31
19
30
25
10
25
40
56
34
36
35
50
210
218
25
23
Median
COHb
Saturation
5.7
5.1
6.0
5.2
6.5
6.8
2.5
4.8
6.0
6.0
5.7
4.4
1.5
5.8
7.1
9.7
4.8
5.6
5.1
5.3
4.6
5.5
5.1
5.8
5.2
6.0
3.7
7.3
8.0
5.6
5.1
4.2
2.8
4.9
6.6
6.0
4.0
5.6
5.9
5.4
5.5
5.4
3.9
5.6
5.4
5.4
4.4
4.0
4.2
90%
COHb
Range
2.0-9.2
2.5-7.2
1.6-7.5
1.7-7.4
1.2-10.1
2.1-9.5
1 .4-9.6
1 .5-8.4
1 .5-8.9
1 .7-9.8
3.2-7.9
2.0-9.8
2.3-8.6
1 .6-9.9
2.0-9.6
2.5-9.4
2.8-9.5
0.8-6.3
1.7-10.4
2.0-10.4
1 .8-9.1
1 .2-8.4
2.0-8.6
1.6-8.5
1.7-9.3
1.4-8.5
1 .4-8.4
1.4-10.4
1.8-9.7
1 .4-8.7
0.9-7.7
1 .4-8.6
1.6-7.5
*For sample sizes less than 20, the 90% COHb range is not computed.
tID Indicates Insufficient data.
1192 JAMA, Aug 26, 1974 • Vol 229, No 9
Carboxyhemoglobin Levels—Stewart et al
-------
Table 3. — Mean COHb Saturation in Cigarette Smokers
One Hour After Last Cigarette
Packs of Cigarettes Smoked Par Day
Location
Milwaukee
New Hampshire,
Vermont
New York City
Washington, DC
Los Angeles
Chicago
Nonsmokar
1.3
1.4
1.4
1.4
2.0
2.0
5 mph
Urban
1.4
1.5
1.9
Suburban
1.3
1.3
1.9
nitude greater than was present in
nonsmokers.
Forty-five percent of the nonsmok-
ing blood donors had COHb satura-
tions in excess of 1.5%. In Denver and
Los Angeles, 75% of the nonsmokers
had COHb saturations more than the
1.5% value.
The median COHb and 90% range
for the various locations within each
of the 18 sampling areas are pre-
sented in Table 2. In each sampling
area, an effort was made to include
persons from urban, suburban, rural,
and airport terminal locations. Blood
samples from persons in urban areas
with high automobile density con-
sistently had COHb saturations great-
er than those measured in persons in
areas of low automobile density. In
New York, this was dramatically evi-
dent in the comparison of individuals
working on Governor's Island where
the average COHb saturation was
0.8%-half that of persons donating
blood in adjacent New York City
areas.
There was a moderately wide range
of COHb saturations observed among
donors sampled in the urban areas.
These urbanites consistently had
higher COHb saturations than those
measured in persons sampled in sub-
urban areas and rural areas.
Both the median and the mean
COHb saturation of blood donors
from the urban areas of Denver, Los
Angeles, and Chicago were higher
than those observed in donors in ur-
ban New York and Washington, DC.
This observation was not proof that
the ambient CO levels in Denver, Los
Angeles, and Chicago were higher
than those in the other two cities, but
that the specific locales sampled had
higher average ambient CO levels
than the average of the locales visited
in New York City and Washington,
DC.
One observation did, however, sug-
gest that the ambient CO levels in
Denver, Los Angeles, and Chicago
were higher than those in New York
City. During the sampling period at
the East Blood Center, a weather in-
version occurred in New York City,
which was associated with COHb sat-
urations comparable to those ob-
served in the other three cities during
fair weather periods.
The COHb saturations of persons
working in the terminals at J. F.
Kennedy and O'Hare International
airports were as high as those from
areas of high automobile density in
New York City and Chicago.
Space limitations preclude a de-
tailed presentation of the influence of
each of the variables on COHb satu-
ration. The in-depth report is avail-
able at the National Clearinghouse."
Tobacco smoking, geographical loca-
tion, occupation, and meteorological
conditions were important variables
influencing COHb saturation whereas
variables such as race, sex, age,
height, and weight were not.
Tobacco smoking was consistently
associated with the _highest COHb
saturations. The quantity of tobacco
used in the previous 24 hours and the
time elapsing since last smoking were
major determinants of COHb levels."
The COHb saturation in smokers ap-
peared to be additionally elevated by
the nontobacco CO sources in the en-
vironment. Note in Table 3 that the
difference in COHb saturation be-
tween the nonsmokers and the smok-
ers remained relatively constant in
each of the six areas, indicating that
the environment was further increas-
ing the total CO body burden of the
smokers. Another author has sug-
gested that "persons with 5% COHb
from smoking do not absorb "further
CO from the environment unless the
ambient CO concentration is 30 ppm
or more,"15 reasoning that the max-
imum COHb saturation obtainable as
a result of continuous exposure to 30
ppm is 5%. The flaw in this reasoning
is that the concentration of CO in to-
bacco smoke reaching the alveoli is
not 30 ppm but approximately 200
ppm. It is logical that intermittent
exposure to 200 ppm superimposed on
a continuous exposure to a much
lower ambient CO concentration
would further increase the CO body
burden. The findings of this investi-
gation strongly suggest this to be the
case.
Higher COHb saturations were as-
sociated with higher hemoglobin con-
centrations." These data are summa-
rized in Fig 3. While this positive
correlation was most striking in the
tobacco smoker, it was minimally but
definitely present in those nonsmok-
ers with the higher COHb satura-
tions.
Barometric pressure, temperature,
visibility, and wind speed were avail-
able from the National Weather Ser-
vice for the sampling sites. Of these
factors, only wind speed was a statis-
tically significant factor influencing
COHb saturation, exerting relatively
minor influence." In Table 4 are data
from three locales that show this in-
fluence.
We have also compiled the COHb
saturation in nonsmokers by occupa-
tion. There were marked differences
between occupational groups. Stu-
JAMA, Aug 26, 1974 • Vol 229, No 9
Carboxyhemoglobin Levels—Stewart et al 1193
-------
dents and housewives had the lowest
COHb concentrations. Other low
COHb groups included those in oc-
cupations associated with mental
health, education, library science, reli-
gion, art, road paving, and entertain-
ment. The vehicle-related occupa-
tional groups had higher COHb
saturations than most groups for
wind speeds greater than 5 mph.
Other high COHb groups included
those associated with metal process-
ing, chemical processing, stone and
glass processing, printing, welding,
electrical assembly and repair, and
graphic art.
Taxicab drivers generally had
COHb saturations among the highest
observed in any occupational group.
In New York City, 14 nonsmokers had
samples taken on Oct 18, 1970. Eight
cab drivers coming from work had a
mean COHb of 2.5% saturation with a
range from 1.3% to 5.8%. Six off-duty
cab drivers coming from home had
COHb saturations ranging from 1.0%
to 1.5%, with a mean of 1.2%. Twelve
cigarette-smoking cab drivers coming
from work had a mean COHb satura-
tion of 6.9% with a range of 3.0 to
13.0%.
In none of the locales studied was
there a sufficient quantity of am-
bient-air CO data to permit correla-
tion with the blood donors' COHb lev-
els. Furthermore, there was poor
correlation between the CO concen-
tration measured in the blood bank
facilities with the ambient CO con-
centration outside the facilities. This
discrepancy was due in part to the lo-
cation of the air intakes for the build-
ings and points to the difficulty in at-
tempting to relate isolated street-
level CO concentrations to a person's
total CO exposure.
Comment
The most relevant finding of this
30-month study was the astounding
observation that 45% of all the non-
smoking blood donors tested had
COHb saturations greater than 1.5%.
In the cities of Denver and Los An-
geles, which feature zones of high
automobile density, fewer than one
quarter of the nonsmoking blood do-
nors had COHb saturations lower
than 1.5%. If current research scien-
tifically validates the Air Quality
Standards for CO, excessive exposure
to CO is widespread and is occurring
regularly. While it was anticipated
that none of the major metropolitan
areas surveyed in 1969-1972 would
meet the Air Quality Standards for
CO, it was surprising to find that the
smaller towns in New Hampshire and
Vermont had ambient CO concentra-
tions above permissible levels.
One reaction to the large number of
nonsmokers with COHb saturations
greater than 1.5% is a temptation to
deny the validity of the observation
by questioning the accuracy of the
COHb analytical method employed.
To answer this charge before it could
be seriously considered, the two ex-
periments described in the investiga-
tion were performed with volunteer
subjects. The two COHb analytical
methods employed detected the low
COHb saturations in the volunteers
who breathed CO-free air. This dem-
onstrated that the analytical methods
possessed the necessary sensitivity to
detect low COHb saturations. Fur-
thermore, the two analytical methods
were able to determine accurately
COHb saturations in the volunteer
subjects exposed to discontinuous and
fluctuating CO exposures in the con-
trolled environment chamber. This
experiment demonstrated that the
methods were accurate throughout
the range of COHb saturations most
critical to the conclusions reached in
this study. Therefore, we contend
that the COHb saturations reported
are accurate and valid.
Of the variables examined that in-
fluenced COHb saturation, tobacco
smoking was the most dominant. Car-
boxyhemoglobin saturations in smok-
ers were proportional to the quantity
of tobacco used and placed the smok-
ing population in an unique group
who are experiencing CO exposures
in an order of magnitude greater
than that experienced by any other
segment of the population. The geo-
graphical location of the individual,
his occupation, and the existing
meteorologic conditions were the
other chief factors influencing the
COHb saturation. Urban dwellers had
consistently higher COHb saturations
than did their counterparts from ad-
jacent rural areas.
Large international airports,
O'Hare and J. F. Kennedy, featured
surprisingly high ambient CO levels,
attributed in part to jet engine CO
production and in part to the heavy
automobile density near the'automat-
ically opening and closing doors at
airport terminal entrances. Persons
with advanced heart or lung disease
planning to travel in aircraft pres-
surized for 6,000 feet could, as a result
of prolonged CO exposure in airport
terminals, unknowingly subject them-
selves to an additional anoxic stress.
While the stability of the hemoglo-
bin concentration in the blood sam-
ples was unknown for the blood sam-
ples analyzed in the investigation, it
was interesting to observe the strong
correlation between elevated COHb
saturations and the corresponding
elevation of hemoglobin concentra-
tion. While it was anticipated that
the segment of the population heavily
exposed to CO as a result of tobacco
smoking would demonstrate a com-
pensatory increase in hemoglobin
concentration, the observed com-
pensatory increase in red blood cell
mass in the nonsmokers with the
higher COHb saturations was not.
Should this finding be corroborated, it
would appear that man has the poten-
tial for compensating for the minor
anoxic stress induced by slightly ele-
vated COHb saturations.
The thought that a recipient of a
unit of blood from a heavy tobacco
smoker would have his total body bur-
den of CO increased raises the ques-
tion of the efficacy of the adminis-
tration of a unit of blood having less
oxygen-carrying capacity than would
a unit from a nonsmoker. The fact
that the biological half-life of CO in
donor blood, once it is circulating in
the recipient, is approximately five
hours indicates that the adminis-
tration of blood from a tobacco
smoker is probably not a serious con-
sideration in the majority of in-
stances. However, in those cases
where the recipient has a seriously
compromised cardiovascular reserve,
the administration of blood with a
high carboxyhemoglobin saturation
might be unwise when the primary
purpose for blood administration is to
improve oxygen transport.
The major purpose of this investi-
gation was to establish the range
1194 JAMA, Aug 26, 1974 • Vol 229, No 9
Carboxyhemoglobin Levels—Stewart et al
-------
of CO exposure experienced by the
American population in 1969-1972. In
accomplishing this task, it has been
established that a great percentage
of its population is chronically ex-
posed to CO concentrations in excess
of those permitted by the Air Quality
Standards. These base line data can
now be used to measure the effec-
tiveness of the antipollution mea-
sures which this nation develops and
employs.
This investigation was performed for the
Coordinating Research Council, Inc, and the En-
vironmental Protection Agency under contract
CRC-APRAC, project No. CAPM-8-68.
Tibor J. Greenwalt, MD, Medical Director of
the Blood Program, the American National Red
Cross, cooperated in this investigation. Hugh C.
Dodd, Sally A. Graft", and Karen K. Donohoo per-
formed the carboxyhemoglobin determinations.
A table of the carboxyhemoglobin saturations
in nonsmokers, by occupation, is available from
Microfiche Publications. Refer to NAPS docu-
ment 02415 for one page of supplementary
material. Order from ASIS/NAPS c/o Microfiche
Publications, 305 E 46th St, New York, NY
10017. Remit in advance $1 50 for microfiche or
$5 for a photocopy. Make check payable to Micro-
fiche Publications.
References
1. Forbes WH, Sargent F, Roughton FJW:
The rate of carbon monoxide uptake by normal
men. Am J Physiol 143:594-608, 1945.
2. Stewart RD, et al: Experimental human ex-
posure to carbon monoxide. Arch Environ
Health 21:154-164, 1970.
3. Peterson JE, Stewart RD: Absorption and
elimination of carbon monoxide by inactive
young men. Arch Environ Health 21:166-171,
1970.
4. Ringold A, et al: Estimating recent carbon
monoxide exposures. Arch Environ Health 5:308-
318, 1962.
5. Peterson JE: Postexposure relationship of
carbon monoxide in blood and expired air. Arch
Environ Health 21:172-173, 1970.
6. Dubowski KM, Luke JL: Measurement of
carboxyhemoglobin and carbon monoxide in
blood. Ann Clin Lab Sri 3:53-65, 1973.
7. Malenfant AL, et al: Spectrophotometric
determination of hemoglobin concentration and
percent oxyhemoglobin and carboxyhemoglobin
saturation. Clin Chem 14:789, 1968.
8. Collison HA, Rodkey FL, O'Neal JD: Deter-
mination of carbon monoxide in blood by gas
chromatography. din Chem 14:162-171, 1968.
9. Dodd HC, et al: Analysis of Carboxyhe-
moglobin with a Helium-lonization Detector. Re-
port No. ENVIR MED MCW CRC-COHb-73-3, to
be published.
10. Baretta ED, Graff SA, Donohoo KK: Anal-
ysis of Carbon Monoxide in the Blood and Breath
of Man. Report No. ENVIR MED MCW CRC-
COHb-73-2, to be published.
11. Stewart RD, et al: "Normal" Carboxyhe-
moglobin Levels of Blood Donors in the United
States, NTIS report No. PB222503. Springfield,
Va, National Clearinghouse for Federal Scien-
tific and Technical Information.
12. Porter K, Volman PH: Flame ionization
detection of carbon monoxide for gas chroma-
tographic analysis. Anal Chem 34:748-749, 1962.
13. Peterson JE, Stewart RD: Predicting the
Carboxyhemoglobin Levels Resulting from Car-
bon Monoxide Exposures. Report No. CRC-
APRAC-CAPM-3-68, MCOW-ENVIR-CO-73-1,
to be published.
14. Coburn RF, Forster RE, Kane PB: Consid-
erations of the physiological variables that de-
termine the blood carboxyhemoglobin concentra-
tion in man. J Clin Invest 44:1899-1910, 1965.
15. Bartlett D: Pathophysiology of exposure to
the low concentrations of carbon monoxide. Arch
Envinm Health 16:719-727, 1968.
JAMA, Aug 26, 1974 • Vol 229, No 9
Carboxyhemoglobin Levels—Stewart et al 1195
Printed and Published in the United States of America
-------
C. DR. EDWARD RADFORD
RECENT STUDIES OF CO IN RELATION TO
HEART DISEASE
-------
Copies of this paper were unavailable for printing. Copies of the
transcript of this portion of the seminar are available for purchase from:
Ace-Federal Reporters, Inc.
415 2nd Street, N. E.
Washington, D. C. 20002
(202) 547-6222
-------
D. DR. STEVEN HORVATH
INFLUENCE OF CO ON THE WORKING
CAPACITY OF MAN
-------
-1-
ENVIRONMENTAL PROTECTION AGENCY
SCIENTIFIC SEMINAR ON AUTOMOTIVE POLLUTANTS
Washington, D.C.
11 February 1975
DR. WISER: Shall we reconvene?
Let's pick up where I left off before. Again, I will repeat, the
next speaker will be Dr. Steven Horvath of the University of California,
who will speak on the "Influence of CO on the Working Capacity of Man."
Dr. Horvath?
DR. HORVATH: Thank you.
(Slide.)
Ladies and gentlemen, Mr. Chairman, I am going to talk about three
topics, really. One of them which will be represented by the first
slide, the second which will be primarily on work capacity and the
third one, which I discussed earlier with Dr. Knelson, to further
amplify some of the work we are doing the the same area of cardiovascular
response.
One of the major problems, of course, as far as carbon monoxide
is concerned, is the effect it may have on certain psychophysiological
problems, and this first slide represents some of the work we have
been doing with the effects of various levels of carbon monoxide on
the ability of the individual to maintain vigilance.
As you can see, the ordinary individual shows a minor decrement,
if he has a vigil of several hours, of one hour duration in this case.
The decrement ordinarily will go from about 90 percent correct responses
to approximately 70 percent after the end of about 55 minutes.
If you put the individual at various levels of carboxyhemoglobin,
there are certain changes which also occur, which are much more dramatic
-------
As you will note, if you are exposed to a level of CO which produces
carboxyhemoglobin of approximately 5.5 percent, there is a marked
alteration in the pattern of this curve, and the vigilance of these
individuals is very strikingly reduced.
There is a slight change at the end of the test, which is
rather typical on most individuals when they know they are being
pulled out of an environment of this sort. This type of vigilance
test is one which required the individual to detect a light, which
has minor degrees of variation in intensity, and this light occurs
at various, unexpected intervals during the time of his exposure.
We have done this with higher levels of carboxyhemoglobin
than S percent, going up to 10-15 percent. One of the most surprising
things is that when you get the individual really stimulated and his
epinephrine levels are higher, then the effect is not as noticeable.
Now, this is just to indicate that the kinds of work that we
have done at the Institute where I an, encompass psychological,
physiological and biochemical problems, and that this is all a part
of an integrated effort in an attempt to estimate the effects of
carbon monoxide on performance.
(Slide.)
Now, this slide represents a type of performance which I am
going to describe in a little more detail later. This has to do with
the ability of an individual to perform a maximal aerobic type of activity.
This is the type of performance in which an individual is pushed
to the utmost extreme and will generally collapse after a
-------
-3-
period of either, depending upon the type of test that we use, a
period of 5 minutes or a period of approximately 22 minutes.
The 5-minute test is a test in which he runs at 7.5 miles per
hour up an 8.6 percent grade, whereas the longer test is one which
we most commonly use because we need to use these tests for older
subjects. This test requires him to walk at a speed of 3.5 miles
an hour at a grade which starts at zero and then increases by one
percent every minute until the individual is unable to continue to
work.
Now, quite a long number of years ago, when I was first exposed
to carbon monoxide, when I was working with Dr. Roughton, one of the
studies we were doing was to see what happened to us in terms of the
carboxyhemoglobin dissociation curve when we were having levels of
carboxyhemoglobin as high as 50 percent.
As a sort of a corollary to that observations, it was noted
that most of us were unable to perform very effectively when we
reached those high levels, and this is not at all surprising, but
in 1940 very few people knew as much as they do today.
However, since that time, there has been a great interest,
mostly recent, in the last four or five years, as to whether or not
an individual's capacity to perform at his maximum level is impaired
by exposure to carbon monoxide.
There were several reports coming out of the Los Angeles area
in which several groups of athletes, swimmers, and runners, reported
a decrement in their performance — and these, of course, are maximum
performance tests - when they are exposed to "smog conditions",
-------
which were unfortunately undefined in terms of either the level of
carbon monoxide or the presence of any other contaminant in the
atmosphere.
It led to a series of studies by a number of investigators
attempting to identify the point at which a level of carbon monoxide
in the blood as carboxyhemoglobin would definitely alter the individual's
capacity to perform this maximum level of work.
Naturally, everybody started at a higher level in order to be sure
they could see the decrement. You can see this in the top portion of
the slide here.
Individuals who are exposed to various levels of carboxyhemoglobin
do show a decrement — a fairly good sized decrement, for example, where
you have about 35 percent carboxyhemoglobin. This is a reduction of
almost 40 percent in the capacity to perform maximum work.
In actuality, this would mean that if you went up a couple more
percent in carboxyhemoglobin to about 55 percent, you would be unable
to do any work of this sort at all. In other words, you start running
and you would be unable to finish the run of more than about four or
five seconds.
This raised a rather important problem, because in reality, the
interest should lie at low levels of carboxyhemoglobin, which are produced,
for example, in these three points over here when an individual is
breathing less than 50 parts per million in the ambient air, which
gives him a carboxyhemoglobin of under or around three percent.
This would indicate that statistically, at least, there is pract-
ically no change or no noticeable detectable change in the maximum
-------
-5-
capacity to perform work at these levels of carboxyhemoglobin.
This figure up here, the one at the top of the line of this first
series of three, is done on a group of smokers who started off with the
higher level carboxyhemoglobin, than people who are nonsmokers.
The first detectable sign of a decrease in the maximum capacity to
perform work was observed when carboxyhemoglobin levels reached 4.5
to 5 percent.
The decrement can be very logically defined as the percent
decrement in terms of the amount of carboxyhemoglobin in this equation
over here.
So, it is quite noticeable that in individuals who are exposed
to carbon monoxide which produced levels of carboxyhemoglobin of 5
percent and up, showed a definite decrement in capacity to perform
maximum type of work.
Now, in part, the difficulty with all of these types of studies,
has been that the type of individuals who have been studied have been
young males. There have been no studies performed on females, children,
or old subjects and up to this moment except for a study we have just
completed, no studies have been performed on middle-aged individuals.
We now have studied a group of individuals between the ages of 45
and 55, who have, of course, as you may recall, a decrement in their
maximum capacity to perform work, which is simply related to the fact
they are getting older. However, regardless of whether they are
getting younger or older, the decrement first shows up significantly
again at about five percent (HbCO).
-------
So, we can definitely state that at least in male subjects,
those between the ages of 19 and 25, and those between the ages of
45 and 50, do have a decrement in their capacity to perform work
which is related to the level of carboxyhemoglobin present in their
blood.
(Slide.)
I would like to present this slide because basically, the much
more important studies that have to be done with exposure to carbon
monoxide do not necessarily relate to the ability to perform maximum
levels of work.
This maximum type of effort is something which an individual only
sporadically engages in, that is voluntarily, except those who are
engaged in performances, like athletes of some sort, or someone who
has to run for a street car and it is four or five blocks away, and
he tries to get there in time to catch it.
Most people perform levels of work which are definitely below their
maximum level of endeavor. However, we are able to relate the capacity
of man to work dependent on the percentage of his maximal capacity.
If we take his maximal capacity, regardless of the method of measurement,
as 100 percent, in the top curve, then we have an indication of how
long an individual can work in terms of hours at various levels of his
capacity.
An individual who has extraordinary — who is extraordinarily well
trained, namely someone such as an Olympic skier, a long-distance runner,
would be able to work for approximately eight hours at about 55 percent
of his maximum capacity. The ordinary individual, which we, of course,
-------
were primarily interested in looking at, because that encompasses
99 percent of the population, are individuals who can work for eight
hours at approximately 30 to 35 percent of tbeir maximum capacity.
You will note that there isn't much difference between working
for four hours or working for eight hours. There is a difference of
about five percent. Ordinarily, most individuals can work for four
hours at about 35 percent or between 35 and 40 percent of their
maximum capacity. It would be quite important to take a look at
individuals who are performing long-term work, rather than those
individuals who are performing short-term work.
(Slide.)
In the first instance, let me say that we have been interested
in two aspects of this. In actuality, some of our studies were
involved with another contaminant, namely, PAN, but we are not
reporting on that here today. This will give you some indication that
what we are trying to do is look at the two environmental factors, in
addition to work, which are involved in the increase in the level of
pollutants, at least in the Los Angeles and Southern California area.
This is related to the ambient environment. So, all the studies
that are going to be reported on are those which have to do with an
ambient environment of 25 C, and another one of 35 C, and these two
environments were selected on the basis of the values which we ordin-
arily see in Los Angeles in the summertime, and values which you
ordinarily see in the wintertime, fall, and spring.
These two curves represent a type of response which is present
in an individual who is working for this length of time (4 hours).
-------
-8-
Now, ordinarily - and I will show you that a little bit later -
an individual working at 25 C would have a heart rate response which
remains constant for about three and a half hours, and then shows a
slight increase. This is the response that you see here, the response
of an individual working for four hours in an environment in which he
is breathing 50 parts per million of CO.
You will note that there is, in this case, a marked change in
the heart rate, and that this heart rate starts increasing at
approximately one and a half to two hours, and goes up to a level
which is at least 15 to 20 beats higher than would have been anticipated
if he had not been exposed to carbon monoxide.
At 35 degrees, you will note that the increment is even steeper.
The heart rate goes up to 140, and the increment continues despite the
fact that he should really have not had much of a change over this
four-hour period.
(Slide.)
One of the factors which, of course, makes for some of the changes
which we will see in performance of capacity of man in this long-term
work has to do with the fact that the 25 C, the ventilation is much lower.
It is somewhere around 23 to 23.5 liters per minute. In the hot envir-
onment, the ventilation — I am sorry, this is the ventilation equivalent,
the efficiency of gas exchange shows quite a bit of difference from
the cool environment at 25 C. It does represent the fact that the
amount of oxygen which the subject extracts from the air is definitely
less at these very hot environments and these work loads.
(Slide.)
-------
-9-
I would like you to ignore the two intermediate points of the
curve and just look at the upper curve and the lower curve here.
Here we again see the striking effect at 25 C of this contaminant
namely compared to filtered air. In these 20 subjects in this case —
with carbon monoxide, you will notice that the difference is quite
striking in this group.
(Slide.)
Now, I would like to go to some other differences here which have
to do with smokers and nonsmokers. I might point out that the
people we selected as smoker subjects were, by the way, an older age
group. This is a group of subjects between 45 and 55, who also perform
the same four-hour task as our other younger subjects did. These subjects
have been selected for no evidence of cardiovascular or respiratory
disorders, despite the fact they were heavy smokers.
Out of the final ten subjects we obtained for this study, we had
interviewed and screened something in the neighborhood of 45 subjects,
35 of whom were eliminated because they could not meet the criteria
for performing this work. It is, I think, rather important to note that
the 45+ year old males who are smokers have a maximum capacity which
is 25 percent lower than their compatriots who are nonsmokers.
At 25 and at 35, these are the differences, showing again that
in comparison with filtered air, this heart rate (over here) at 25°C
and this one (over here) at 35°C are higher when breathing 50 ppm CO
for four hours. You again see that it goes up very much higher.
The stroke index which is another measure of the cardiovascular system —
at 25 C, the stroke index actually goes down a little, indicating
-------
-iU-
a very interesting change in the pattern of events and at 35 C, the
stroke index is markedly diminished so that it drops about 20 percent
over four hours, (indicating).
This is primarily due to the fact that the cardiac output in
these individuals does not change over the four-hour period, but the
heart rate does change, and consequently, the amount of blood pumped
out by the heart per beat is much less.
(Slide.)
This again indicates some of the difference between smokers and
nonsmokers in filtered air and with carbon monoxide. The respiratory
exchange ratio for the smokers and those in carbon monoxide are much
higher. Compared to filtered air the nonsmokers are way, way, down
over here and the others fit in between.
Age makes a difference in the ability of the individual to respond
in some of his cardiovascular responses.
(Slide.)
One of the last studies which we have just finished, which is
going to be published, is one which had a certain significance because
it relates to the effect on the performance capability of an individual
in relationship to the level of CO in the ambient air if he first
receives a bolus of CO, so as to bring his carboxyhemoglobin to about
3.6 percent.
The individual here is initially sitting quietly. He is given
carbon monoxide, a little bolus. When his carboxyhemoglobin reaches
about 3.5 percent, he then starts breathing 20 parts per million of
CO in the ambient air.
You will note there is a nice maintenance of the HbCO (blood) during
the rest period, and then there is essentially a continued maintenance
despite a period of increasing activity.
-------
-11-
I would like to have you take a look at what happens here in
the amount of air that the individual moves during this activity.
He starts off about 10.5 liters when he first starts exercising and
gradually goes up to about 80 liters, but note that his carboxyhemoglobin
stays very constant.
There is a change in the CO capacity of the blood. This is fairly
suggestive and an important sort of observation because it indicates
that at any time that individual gets a certain burden of CO (in terms
of carboxyhemoglobin), the maintenance of this level of blood CO can
be produced with a very, very low level of carbon monoxide in the
ambient air that he breathes.
(Slide.)
I will just go on to this slide here to sort of have you take a
quick look at what we have been doing with dogs measuring the percent
change in coronary blood flow with various levels of carboxyhemoglobin.
You can see that even at five percent carboxyhemoglobin in normal
animals, there is an increase of about 10-20 percent in the coronary
blood flow. It reaches a stable point at around 35 percent increase.
I can say that at this same level of reduction in the amount of
available oxygen, by exposure to low oxygen, the coronary blood flow
in normal animals goes up about 300 percent. There is a very great
difference in the kind of response observed.
The interesting thing about this is the fact that we have now just
finished a study which is now — in the analysis stage. We have been
studying dogs which have had pacemakers installed. They have had their
auricular-ventricular node and their Bundle of His destroyed.
-------
-12-
Therefore, they are having discontinuity between the activity of
the ventricle and of the atrium. In order to correct it, you put in
a pacemaker. The interesting thing about these studies is that those
animals do not respond to a stimulus of CO load by increasing their
coronary blood flow. This raises some very interesting suggestions
in terms of their performance in a polluted environment.
Thank you.
DR. WISER: The paper is now open for discussion.
MR. WEINSTOCK: Weinstock for Ford. I am very interested, Dr.
Horvath, in — when you compare smoker and nonsmoker, do you take the
smokers and sort of clean them out with oxygen, so they get their
carboxyhemoglobin down to the nonsmokers, and then is there still the
same difference?
DR. HORVATH: We have done about a half a dozen individuals who
are pretty heavy smokers in that way. They are people who go up to —
have HbCO levels of up to around ten or eleven percent. We reduced them
down. Their capacity to perform work is still reduced.
MR. WEINSTOCK: They are apparently -
DR. HORVATH: It is not the presence of the normal four to seven
percent carboxyhemoglobin that they have that results in this decrement.
If a smoker gets in there in the first five minutes of a 15-minute
test, for example, which is all he can do, his carboxyhemoglobin level
will be falling, because he will be ventilating so much more.
In actuality — when he goes in the condition of filtered air, he
is having less carbon monoxide present than the other individual
(non-smoker) has when he is breathing carbon monoxide.
-------
-13-
MR. WEINSTOCK: He is showing withdrawal symptoms?
MR. WASLER: Wasler, GM Research. Dr. Horvath, you have presented
a series of figures with quite impressive observations. However, would
you please comment also what was the number of persons, what was the
number of observations, and how large was the individual variance and
what was the statistical significance in your individual tests?
DR. HORVATH: Yes. In each of these studies, there were 20 subjects
in the younger age group and 18 subjects in the older age group. It
is very difficult to get people between 45 and 55 to decide to perform
either hard work or even long-term work without their getting into
serious — into some difficulty.
We had to be very careful in selecting those individuals who did
not have any electrocardiographic evidence of disturbance during the
time they were doing this preliminary stress test.
So, these are not normal older people. These are selected older
people, and I think that should be kept in mind.
The variance in this group was very small, and I don't recall
offhand the figures, but they are already in the published literature.
The statistical significance showed up at the five percent level
at 4.2 percent carboxyhemoglobin.
DR. RADFORD: Steven, I am very interested in the ventilatory
responses you observed. It suggests that perhaps there was a differ-
ence in lactacidemia, for example, at the higher work levels.
Have you measured that and have you checked on pH changes?
DR. HORVATH: Yes. We did blood pH and there is no difference.
DR. RADFORD: And no difference in lactacidemic, either?
-------
-14-
DR. HORVATH: These individuals in their maximum test run
anywhere between 12 and 14 milli-equivalents of lactic acid at the end
of the tests. We pushed these individuals to the utmost, and they
have been pushed. This is a stage at which an individual practically
collapses so that they have high levels of lactic acid, so they
both are anaerobic and these aerobic states were really stressed.
We pushed them to the point where in actuality, there could be
no difference.
DR. RADFORD: The point is, if they were getting there on the way
and you showed a continuum as a function of time, if you are postulating
that muscle hypoxia is a limiting factor in their work capacity,
wouldn't that show up as a higher lactic acid level earlier?
DR. HORVATH: Well, frankly, we are pietty convinced that the way
in which you look at lactic acidity in most people — not you, excuse me —
but most people have looked at lactic acid, doesn't really give a good
representation of what is happening in an aerobic state.
It is a rough approximation and can be defeated by the subject
very readily if he wants to.. It is not a good way of representing
maximum performance.
DR. WISER: Thank you, very much.
-------
INSTITUTE OF ENVIRONMENTAL STRESS
Publications and Manuscripts
Concerning Carbon Monoxide
2/1/75 Steven M. Horvath
Director
PUBLISHED
Raven, P. B., B. L. Drinkwater, S. M. Horvath, R. 0. Ruhling, J. A. Gliner,
J. C. Sutton, and N. W. Bolduan. Age, smoking habits, heat stress,
and their interactive effects with carbon monoxide and peroxyacetyl-
nitrate on man's aerobic power. Int. J. Biometeor. 18(3): 222-232,
1974.
Dahms, T. E., and S. M. Horvath. Rapid, accurate technique for
determination of carbon monoxide in blood. Clin. Chem. 20(5):
533-537, 1974.
Drinkwater, B. L., P. B. Raven, S. M. Horvath, J. A. Gliner, R. 0. Ruhling,
N. W. Bolduan, and S. Taguchi. Air pollution, exercise, and heat
stress. Arch. Environ. Health 28: 177-181, 1974.
Raven, P. B., B. L. Drinkwater, R. 0. Ruhling, N. W. Bolduan, S. Taguchi,
J. A. Gliner, and S. M. Horvath. Effect of carbon monoxide and
peroxyacetylnitrate on man's maximal aerobic capacity. J. Appl.
Physiol. 36(3): 288-293, 1974.
Raven, P. B., B. L. Drinkwater, and S. M. Horvath. Physiological effects
of air pollutants during long and short term work in 25°C and 35°C
temperature. Final report on Grant ARB-2098 of the California State
Air Resources Board, June, 1974.
Horvath, S. M. Effects of carbon monoxide on human behavior. IN:
'Proceedings of the Conference on Health Effects of Air Pollutants,
Assembly of Life Sciences, National Academy of Sciences - National
Research Council, October 3-5, 1973, pp. 127-144.
Horvath, S. M., T. E. Dahms, and J. F. O'Hanlon, Jr. Carbon monoxide
and human vigilance: a deleterious effect of present urban
concentrations. Arch. Environ. Health 23: 343-347, 1971.
Horvath, S. M., P. B. Raven, B. L. Drinkwater, J. F. O'Hanlon, and
T. E. Dahms. A brief literature search regarding the influence
of air pollutants on work capacity and psychophysiological
responses of man. Proj. Clean Air Task Force Assessments,
2: E-l-25, 1970.
Horvath, S. M., J. F. O'Hanlon, Jr., and T. E. Dahms. Carbon monoxide
and vigilance: potential danger from existing urban concentrations.
Proj. Clean Air Rep., 2: 1-11, 1970.
-------
(CONTINUED)
INSTITUTE OF ENVIRONMENTAL STRESS
Publications and Manuscripts
Concerning Carbon Monoxide
Horvath, S. M. Effects of carbon monoxide during exercise. Section V
of National Research Council Panel on Carbon Monoxide report to
the U.S. Senate Committee on Public Works, 1974.
Horvath, S. M. Populations especially susceptible to carbon monoxide
exposure owing to reduced oxygenation at altitudes above sea level.
Section VII(D) of National Research Council Panel on Carbon Monoxide
report to the U.S. Senate Committee on Public Works, 1974.
MANUSCRIPTS IN PRESS
Dahms, T. E., S. M. Horvath, and D. J. Gray. Technique for accurately
producing desired carboxyhemoglobin levels during rest and
exercise. J. Appl. Fhyaiol.
Horvath, S. M., P. B. Raven, T. E. Dahms, and D. J. Gray. Maximal
aerobic capacity at different levels of hemoglobin. J. Appl.
Phyeiol.
Wagner, J. A., S. M. Horvath, and T. A. Dahms. Carbon monoxide
elimination. B&apir. Physiol.
MANUSCRIPTS SUBMITTED OR TO BE SUBMITTED
Gliner, J. A., P. B. Raven, S. M. Horvath, B. D. Drinkwater, and
J. C. Sutton. Man's physiologic response to long-term work
during thermal and pollutant stress. J. Appl. Physiol.
Horvath, S. M. Influence of carbon monoxide on cardiac dynamics
in normal and cardiovascular stressed animals. Final report
on Grant ARB-2096 of the California State Air Resources Board.
Raven, P. B., B. L. Drinkwater, J. A. Gliner, S. M. Horvath, and
J. C. Sutton. Spirometric changes following long-term work
in polluted environments. Environ. Res.
-------
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CO Smokers
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-------
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-------
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-------
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-------
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-------
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-------
E. DR. DANIEL MENZEL
NEW PATHWAYS OF SULFATE AND
NITRATE TRANSPORT IN THE LUNGS
-------
Copies of this paper were unavailable for printing. Copies of the
transcript of this portion of the seminar are available for purchase from:
Ace-Federal Reporters, Inc.
415 2nd Street, N.E.
Washington, D. C. 20002
(202) 547-6222
-------
F. DR. RUSSELL P. SHERWIN
NO 2
-------
Statement by Dr. Russell P. Sherwin
(OPTIONAL INTRODUCTION: Mr. Chairman, colleagues, ladies and gentlemen, I
very much regret that I cannot be here to present the findings from my research
laboratories to you, and especially to answer questions that you may have con-
cerning my presentation. Unfortunately this meeting is in conflict with my
participation as a committee member at a meeting now in progress under the
auspices of the National Cancer Institute. A very brief summary of my back-
ground is: 1) Hastings Professor of Pathology at the University of Southern
California, 2) Full time research work in investigations of hvman and animal
diseases, 3) Special interests in diseases of the lung, cancer, and disturbances
in the white blood cell defense system of the body.
With respect to nitrogen dioxide, the pollutant primarily studied in my
laboratory, it is important that I acknowledge at the outset that I do not
believe a precise NO air quality standard can now be established on the basis
of presently available clinical and research findings. This could be
interpreted to mean that less than stringent standards are acceptable but the
trend of my own research findings and the support of work being done by others
tells me that we should be concerned about NO at the 0.5 ppm level. In Los
Angeles it is common to have levels of 1.0 ppm N0? and, although this is a
peak value, I believe it to be much more important than daily, monthly or
yearly averages. To use an analogy for placing emphasis on peak values, the
threshold for lung damage should be considered in the same light one would
evaluate tide damage to homes built on the ocean shore. The real concern is
not the average tide mark but the level the tide reaches at the flood mark.
Certainly the annual averages currently in use can have little meaning. Un-
questionably, other investigators may take issue with these opening remarks
and I believe it is now appropriate to discuss briefly why such a broad
-------
Sherwin, R.P.
latitude of expert opinion exists in the area of air pollution and its
health effects.
The most important aspect of any problem is its definition. I do not
believe we have really come to grips with defining the air pollution problem:
it is a matter of record that the majority of research workers in the field
have not participated in a seminar with a specific mandate for defini-
tion. The NSF report was an important but limited step in this direction. In
this presentation I will give you my working definition but I would first like
to consider some of the older approaches to the nature of the problem.
As you have heard, both mortality and morbidity have been stressed as
meaningful measurements of the adverse effects of air pollutants. While there
is value to their use, mortality figures offer far too crude an index of
adverse effects, and morbidity figures cannot meet many of the needs as I
hope to show later on. In effect, both mortality and morbidity are "tips of
the iceberg" and for every recorded death and illness there are many thousands
of individuals who have subclinical signs and symptoms, i.e. they do not come
to the attention of the clinician or epidemiologist. In essence, there is
reason to believe that the well population is not very well. For example,
when one looks at the lungs of people of all ages who die from non-pulmonary
diseases, it is readily apparent that no adult, or even young adult, is free
of lung disease. At autopsy, lung scarring, emphysema and a great number of
other abnormalities are commonly found. It is a question of determining
whether the damage is little or great, something now being done by patholo-
gists with less than satisfactory precision. Again, not all my colleagues
may agree with my opinions but I am convinced that lung disease is the most
under reported of human diseases. My impressions from autopsy data have the
support of the clinicians. Several studies have been made where the well
population was tested for pulmonary function capacity and, bearing in mind
-2-
-------
Sherwin, R.P.
the relatively crude indicator provided by our present routine pulmonary
function tests, it appears that at least one of six of our working force,
young adults and adults, may have lost as much as 50% of his or her total
lung tissue. I base this statement, admittedly without adequate scientific
experience froro
documentation, on/the Chest Service at the USC-LACH Medical Center. Dr.
Balchum tested several thousand presumably healthy workirg people of all ages
and reported that one of six had an abnormal pulmonary function test. The
opinion Dr. Balchum and I reached from a consideration of our combined medical
experience from clinical and autopsy studies is that a person probably loses
50%,and possibly more, of his total functioning lung tissue before pulmonary
function tests become definitely abnormal. This tentative judgment demands
confirmation or denial. It is also pertinent to mention that a recent study
(1975) has shown approximately 21% of a general population sample in a
household to have "abnormal spirometry," and other such studies have reported
essentially similar results. When clinical symptoms such as cough and pro-
duction of sputum are considered, nearly half of the population is then found
to be suffering from some degree of respiratory tract disease. Thus, I
strongly believe that the main reason we cannot now show a link between air
pollution and lung disease is that the lung disease entities themselves have
not been properly recognized, defined and quantitated. Furthermore, in
addition to recognizing known lung diseases, there are unquestionably many
entities not yet discovered or only partially uncovered. Most importantly,
the nature of most of our lung diseases, especially emphysema, forces us to
consider a different view of the problem of air pollution and health effects.
It takes twenty years or more of persistent, slow, and silent destruction of
lung tissue before emphysema comes to the attention of either the patient or
the physician. At that time the disease is irreversible with probably two
thirds or more of the lung tissue having been lost.
-3-
-------
Sherwin, R.P.
Further, pathologists do not, for the most part, diagnose emphysema
properly. For one thing, the lung must be fixed by perfusion in order to
arrive at a proper interpretation. As far as I know this is not done in most
of our teaching and general hospitals throughout the country. Thus, we have
no baseline on the true incidence of the emphysematous diseases. Nor do we
know with any reasonable scientific accuracy how rapidly emphysema is
increasing, although there is an estimate that the incidence has quadrupled
over the past few years. The meaning of this is that on one hand we know
that we are faced with a number of noxious substances in our community air,
and on the other hand there are many lung diseses where both cause and fre-
quency are unknown. If we now had an appropriate baseline for the status of
lung diseases in the general population, we would be in much better position
to make meaningful health correlations with new and old air pollutants as
they intermix and change in concentration,and as they relate to human disease
in the young to old populations. To confirm the relationship which I believe
exists between air pollution and emphysema, it is obvious that our present
approaches to establish criteria for air quality standards are inadequate
since 1) the mortality figures concerning emphysema are basically unreliable
even with autopsy data, 2) a valid clinical diagnosis cannot be presently
made, and 3) the clinical signs and symptoms may indicate any of several
chronic obstructive respiratory diseasesjor other lung diseases.
At this point I wish to turn quickly to a definition of the problem. As
I see it, the concept is simple but the demands for a comprehensive under-
standing are overwhelming and the biomedical aspect highly complex. The
simple part is that we are faced with nothing more nor less than an ecology
problem. The ecology is however something we have given little thought to,
the microecology of the human body, that is the complex cell societies that
make up the organs and tissues of our bodies. We are continually amazed by
the complexity of the job each cell carries out. We are also discovering
-------
Sherwin, R.P.
new cell types in every organ of the body and it is most incredible to find
that two cells of identical appearance can have extraordinarily different
functions, a good example being the lymphocyte which in the past few years
has been found to be represented by several species. We know practically
nothing about what each kind of lymphocyte does and this has led to a strong
trend to conserve lymphocytes of different origins, as for example those
from tonsils, appendix, and the axilla of women with certain kinds of breast
cancer. Interestingly enough, lymphocytes and other white blood cells,
hounds
especially macrophages, are, to use an analogy, like blood_/since they seek out
abnormalities in cells that we are unable to detect. Presumably, these
leucocytes can recognize damaged lung cells and either help them to get better
or kill them if the damage is irreversible and presumably a threat to
neighboring cells. We are just beginning work at the 0.4 ppm level in this
area having shown earlier that this "macrophage congregation" phenomenon
increases in the lungs of animals exposed to 10 ppm NO . In addition, there
may be a "primitive" form of a bacterium in the cells which is a target for
the leucocytes; we have reported a possible relationship between such forms
and exposure to NO .
We have also noted a very germane microecology event; exposing guinea
pigs continuously to 2 ppm NO. over a one to three week period leads to a
detectable increase in both the numbers and size of the Type II lung cell,
presumably at the expense of the Type I cell. This population shift may be
reversible but we do not know whether or not this is true at this time.
Since the Type I cell is the "breathing cell" of the lung and gas exchange
is greatly hindered by the very thick Type II cell which replaces it, this
population shift or change in the cellular ecology is reasonably assumed to
have important health meaning. We developed an image analyzer method for
counting cell populations since the more subtle is the exposure the greater
-5-
-------
Sherwin, R.P.
must be the magnitude of quantitation. These studies confirmed earlier
work and of course greatly speeded up the quantitation. To date we have not
had the fundinp, needed to apply this methodology to studies involving levels
lower than 2 ppm NO .
To gain insight into whether or not functional abnormalities might
coexist with, if not be directly related to changes in cell populations, we
have introduced a number of new methods for detecting leakage of protein
from the lung. Our latest findings show that continuous NO exposure at 0.4
ppm for one to three week periods results in an increased protein content in
the airways and air spaces of the exposed animals. At the same time we have
shown that this effect may be systemic in that the amount of protein in the
urine is also increased in the same exposed animals. The urinary tract
studies are now being expanded to include electronmicroscopic studies of the
kidneys, water balance studies and measurements of excretory products in the
blood and urine. We have also carried out a number of other studies: a
chemical in blood that is concerned with oxygen transport (diphosphoglycerate),
acid phosphatase content of lung tissue separated into fine components by
ultracentrifugation, and image analyzer measurements of emphysema. These
studies have given us results which indicate that we should very definitely
be concerned about ambient levels of N0? at the 0.4 ppm concentration. We
have other supporting data which are presently unpublished. I can say at
this time that we have achieved confirmation of some of our findings with
0.4 ppm NO and we have found new evidence of pathophysiologic disturbances
in the lungs of the mouse and guinea pigs at the 0.4 ppm level.
All of the foregoing have stressed one air pollutant, nitrogen dioxide,
and our program calls for a study of other air pollutants singly and in
various combinations. Admittedly, the results will still deal with patho-
physiologic data based on animal studies. However, each indicator we have
used and plan to use was carefully selected for relevancy to human disease.
-6-
-------
Sherwin, R.P.
The increase in numbers and size of Type II pneumocytes that we found in
our animal studies is a common denominator for a great many human lung
diseases^and is a key part of a recently uncovered human lung disease of un-
known cause, namely desquamative intestitial pneutnonitis. Similarly, protein
loss in the lung is another very important early finding with respect to both
human and animal lung disease. Finally, our work with leucocytes is in line
with that of others who are concerned about impairment of the defense system
of the lung by air pollutant exposures.
At this point and as concluding remarks, I would like to give my reasons
for defining the air pollution problem as a microecologic concern, and
present tentative conclusions as to how this concept can be employed to assist
in the establishment of air quality standards for NO and other pollutants.
First of all, the cell societies which make up the human body have always
been and will continue to be at war with their environments, and even with
themselves. It is the nature of life. However, as with the general ecology,
there are some battles that we cannot afford to lose. The extinction of one
species of life or progressive dominance by another has the potential of far
reaching, even devastating effects. Similarly, some special types of cells
cannot be lost or excessively reduced in number. When considering standards,
it is necessary to bear in mind that not only people but some cell types are
particularly vulnerable to damage; others may be especially resistant. For-
tunately, we humans have been endowed with a great deal of reserve strength
in the form of duplicate organs and a high capacity for defense and repair.
These reserves cannot of course be maintained intact; one of the costs all
of us must pay for air pollution is the expenditure of tissue and functional
reserve strength. The key question is what constitutes a reasonable expendi-
ture of this reserve, and what increment in expenditure is caused by rising
or new pollutants in the air we breathe. We should for example know how
many alveoli are lost each day, or some other meaningful period of time, not
-7-
-------
Sherwin, R.P.
as an average per person but according to low, high and intermediate sus-
ceptibility groups of people. With information, based on lungs derived from
the Medical Examiners Office (which should be deemed a national priority),
from general autopsy services, and from animal studies, correlations can be
made with the vaious air pollutant levels. Note that every city has its own
peculiar kind of air pollution although many share air pollution features in
common. The emphysema aspect represents just one)but a complex facet of the
lung disease-air pollution problem. There are many others for the lung as
well as many for each of the different organ systems. For example, studies of
urinary protein levels in various human populations according to air pollution
characteristics,has the potential, in my opinion, of providing a useful
criterion for assistance with air quality standards. This would be a begin-
ning to a multidiscipline study of kidney function in health and disease as
it relates to ambient air pollution.
Lastly, all of thse considerations lead me to state that prime attention
for air quality evaluation should be given to that state of health character-
ized by subclinical abnormalities, or what I have chosen to call morbility.
Further, we should give reasonable credibility when we consider air quality
standards to the relatively few tests we now have available as indicators of
air pollution's influence on this state of morbility. All of know we are
faced with a very difficult cost-benefit evaluation. It is quite clear we
cannot have absolutely clean air. But we also cannot afford to overlook
relatively subtle insults. The possibility is real that cumulative insults,
or even relatively short insult periods, can result in serious clinical
disease, often not in a direct manner but by insidiously initiating, pro-
moting, or aggravating a series of ecologic events within our cell societies.
In this sense we are obligated to attribute to air pollution a causative
role in the production of a new kind of lung disease. I have termed this
-8-
-------
Sherwin, R.P.
disease "pulmonary hypeinopenia," that is an abnormal loss of lung reserve
capacity. It is no less important a disease because it is cryptic. It is
a weak link which makes every organ in the body far more vulnerable to disease,
and far less capable of recovering. The prevention of this disease is an
urgent national priority.
Thank you for your patience, especially for a presentation where time
did not permit the kind of preparation I desire.
-9-
-------
G. DR. A. P. ALTSHULLER
AEROMETRIC DATA ANALYSIS
-------
0.30
0.25
0.20
T
APPROXIMATE UPPER LIMIT
OBSERVED OXIDANT
o
X
o
0.15
0.10
0.05
I
I
I
I
0.5 1.0 1.5 2.0
NONMETHANE HC, ppm C
2.5
i-. V>-;- ;""i^*.
.
-------
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PHILADELPHIA
.35
.30
.25
< .20
O
O
IU
cc
.10
.05
POINTS COMPUTED FROM DIMITRIADES' SMOG
CHAMBER RESULTS
I1
POINTS COMPUTED FROM PHOTOCHEMICAL
MODEL DODGE
ULC
J L
0.5
1.0
1.5 2.0
6-9 AM NON-METHANE HC, ppmC
1.0
1.5
2.0
fcfc
-------
CORRECTED OXIDANT, max. hr, ppm
-------
WASHINGTON, D.C.
.35
POINTS COMPUTED FROM PHOTOCHEMICAL
MODEL-DODGE
POINTS COMPUTED FROM DIMITRIADES' SMOG
CHAMBER RESULTS
1.5 2.0 0-5
6-9 AM NON-METHANE HC, ppmC
-------
DENVER
.35 —
POINTS COMPUTED FROM PHOTOCHEMICAL
MODEL DODGE
OINTS COMPUTED FROM DIMITRIAOES' SMOG
HAMBER RESULTS
1.5 2.0 0.5 1.0
6-9 AM NON-METHANE HYDROCARBON CONCENTRATION, ppmC
-------
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-A-
-------
H. DR. BASIL DIMITRIADES
CHAMBER STUDIES
-------
Scientific Seminar on
Automotive Pollutants
Washington, D.C.
Feb. 10-12, 1975
The Role of NQX in the Ambient N02 and
Oxidant Problems. Smog Chamber Studies
B. Dimitriades
Unlike the aeromctric data, the smog chamber data available are
sufficiently complete to define the role of NOx in the smog formation
process in dctai1. Thus, based mainly on past smog chamber studies,
and to some extent on on-going studies as well, we have been able to derive
complete relationships defining the dependence of oxidant and N02 on
their precursors, HC and NOx- It should be noted that since real atmos-
phere conditions cannot be simulated perfectly in the smog chamber, there
are some questions whether these chamber based relationships are appli-
cable to the real atmosphere. Nevertheless, we accept that these
relationships, qualitatively, at least, are valid, although not so
quantitatively.
One way to depict the role of NOX in the oxidant and N02 formation
process is illustrated in slide 47.
Slide 47 illustrates the chemical processes occurring when the
primary pollutants HC and NO are irradiated in air by sunlight. NO is
converted into N02, and after nearly all NO has been converted, oxidant,
mainly 03, begins to form and accumulate. The speed of this process
depends on the HC concentration. In atmospheres with lower HC concen-
tration, as e.g. after a few years of HC control, NO is oxidized very
slowly, and only at the end of the irradiation (or of the "day", so to
speak) 03 will begin to form. Conversely, when the NO concentration
is lower, the NO oxidation will be completed sooner and 03 formation
also will begin sooner; and, of course, resultant N02 concentration will
be lower, as expected.
It was irradiation experiments such as this that were conducted in
order to study the dependence of oxidant and N02 on the HC and NOX
precursors. It is important to stress here, that, in these studies the
irradiation time and light intensity were designed so as to roughly
simulate conditions in the atmosphere directly above an urban center.
No provisions were made to simulate conditions in city air masses as
they move downwind into non-urban areas. Therefore, the role of NOX
that I will be discussing is the role of NOx in the urban 03 and urban N02
problems. Following this discussion, I will then report some more recent
findings and make some reasonable speculations regarding the role of NOX
in the non-urban pollution problems, as such role is surmised from both
the old and new evidence.
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The dependence of "urban" oxidant on NMHC and NOX is depicted in
slides 1 and 2. Note in slide 1 two things of significance: First,
high 0^ concentration can form from extremely low HC and NOX concen-
trations, and, second, maximum 1-hour 03 increases with NMHC. 1 should
mention here that there are indications, that at extremely high HC con-
centrations the curve has a maximum, that is, 63 decreases with further
increase in HC. Such high HC/NOX ratios do not occur in urban atmos-
pheres and that is why such ratios were not included in the early studies.
However, we now know that such ratios arc common in non-urban atmos-
pheres and we are about to start a systematic study of mixtures at such
ratios.
If the 03-to-HC dependency for non-urban atmospheric mixtures indeed
has a maximum, this would raise some extremely interesting implications; |_
namely, it would suggest that one possible reason why high 03 concen-
trations do not occur everywhere in the countryside, simply is that the
HC/NOx ratio is too high. i
The dependence of 03 on NOX is shown in slide 2. Note here that
for HC, NOX concentrations comparable to those in urban atmospheres, r
the 03-to-NOx dependency shows a maximum, meaning that NOx control will £
not necessarily cause an 03 reduction—in fact, it may cause an 03 increase. (?<
Before I elaborate further on the role of NOx in the oxidant problem, j
I would like to present similar diagrams depicting the dependence of N02 :
on the HC and NOX precursors. These dependencies are depicted in slides •
9 and 48. Slide 9 shows maximum N02 as a funciton of NOX and HC-obviously,
maximum N02 seems to depend only on NOX. Slide 48 shows effects on N02 ,
dosage, and shows that again the main effect is by NOX, but HC also seems !
to have a small effect, a negative one. Needless to say, from what we *«'
know about the mechanism of these reactions, all these effects make per-
fectly good sense. ^
«*•
From the evidence presented so far, we can summarize the role of NOx f
in the urban oxidant and N02 problems as follows: Control of NOx will I
definitely reduce ambient N02, but may or may not decrease oxidant--in '.-
fact, it may increase oxidant. Control of HC will reduce 03 and will have !*'
only a slight effect on N02. Incidentally, the N02 problem and its 't''
dependence on various factors, we now realize, is more complex than I •'
just described, and we are now reexamining it in more depth. I
Let me elaborate, now, further on this NOX role. Another way of J
depicting the role of NOX (and HC) in both the 03 and N02 problems is
shown in slide 49. Slide 49 shows a family of 03-isopleths, each representing
all combinations of HC, NUx corresponding to a certain 03 concentration.
Slide 49 also shows a family of N02-isopleths (2), each representing all I
IIC, NOX combinations corresponding to a certain N02 level. ^-
-------
SLIDE 1. THE DEPENDENCE OF OXIDANT ON HYDROCARBON
O-
Q.
X
o
.b
.4
.2
N0¥: 0.08 PPM
A
NO : 0.2 PPM
A
NOV: 0.4 PPM
A
1.0 2.0
1.0
2.0 3.0
1.0 2.0
3.0
NON-METHANE HYDROCARBON, PPMC
-------
02 0) 0.4
05 06 07
NO, . ppir.
0.1 09 10 II 1.2
Slide 2. Maximum oxidant as a function of NOX at various total hydrocarbon levels.
-------
Slide 9. The Dependence of Max--N02'on NMHC and NOX.
o.
a.
0.9
0.8
0.7
0.6
n c
0.5
-;. 0.4
x
0.3
0.2
0.1
NMHC: 0.1-4.8ppmC
0.1 i 0.21 0.3J 0.4;
0.5 0.6 0.7!
INITIAL NOX, ppm
0.81 0.9) 1.00 i
1.101 1.20»l 1.38 I
J
-------
Slide 48. The Dependence of N0£ Dosage on NMHC and NOX.
CD
-------
From slide 49, we can see that in order to achieve the 03 and
N02 standards, NOX must be reduced down to 0.35 ppm and IIC down to less
than 0.75 ppmC. Note, however, that if NOx drops below the 0.35 ppm
limit, then the 63 will exceed the standard. This has one important
implication:
--Reduction of NOX beyond the 0.35 ppm limit will necessitate
additional HC control, if the 03 standard is to be achieved. In fact,
since there is random, unavoidable variation of NOX, up and down, it
follows that HC must be kept well below 0.75 ppmC in order to insure
that the 03 standard is achieved at all times.
In summary, the smog chamber data suggest that under urban
atmosphere conditions, 03 levels exceeding the standard can form even
when the HC and NOX concentrations are down to extremely low levels,
i.e. comparable to the background levels. These data suggest further
that in order to achieve the oxidant and NC>2 standards in an urban air,
it would be almost imperative to coordinate emission control so as
to lower the HC-to-NOx ratio rather than to drastically control HC and
NOX, in an uncoordinated fashion. The advantage here is, of course,
in that we make use of the inhibitive effect of NO to keep the oxidant
low.
Now what do the chamber data tell us about the non-urban 03 problem?
Incidentally, in non-urban areas, we have found only 03 to be a problem,
not N02. The smog chamber data do not answer our questions regarding
the non-urban 03 problem, but they do give us some useful hints.
First, let me stress that at present we are not clear as to where
does the non-urban 03 come from. Two theories are being considered right
now. By one theory, such 03 forms from anthropogenic emissions, HC and
NOX( discharged in cities—large and small — and transported into the
non-urban areas. If this theory is correct, then the smog chamber data
suggest that our only option is more stringent HC control than what is
called for by the urban 03 problem.
However, there is another theory that explains the non-urban 03.
By this theory, much of the non-urban 03 is a result of combined action
of anthropogenic and natural emissions. To explain, natural emissions
alone have a HC/NOX ratio that is too high to form significant 03
buildup. However, mixtures of natural and the rich in NOx anthropogenic
emissions have lower HC/NOX ratios that are more conducive to 03 formation.
This in essence means that, by this theory, the non-urban 03 forms from
natural HC and anthropogenic NOX. If this theory is indeed correct,
then the non-urban 03 problem would call for more NOX control that what
the urban problems dictate.
This is the role of NOX (and of HC) in the ambient 03 and N02 problems,
as such role is suggested by the smog chamber data presently available.
iK''V^ ^*W^£''*£^^^
-------
AMIS1UALN02IVEAN
0.06 ppm
WAX. 1-HOUR 03
0.30 ppm-03
«-i-j „« « NMHC, ppmC
'Slide 49. Ozone and N02 Isopleths Based on Smog Chamber Data.
-------
4 -
It should be stressed that much additional smog chamber work is needed--
some is currently under way—addressed to the follwoing still existing
problems/questions:
1. What arc the relative roles of HC, NOX in oxidant formation
under "transport" conditions—that is, in city air masses
transported downwind—relative to those under non-transport
conditions.
2. What is the 03 dependence on HC, NOX in simulated rural
atmospheres, that is, in atmospheres with HC makeup and
HC/NOX ratios similar to those in non-urban areas.
3. What will be the impact of currect HC control on the 03/HC/NOX
and N02/HC/NOX relationships.
4. Lastly, but perhaps most importantly, develop smog chamber
methodology such that resultant smog chamber data would have
quantitative validity, that is, direct applicability to the
real atmosphere.
-------
I. DR. JAMES MAHONEY
NATIONAL ACADEMY OF SCIENCES VIEWPOINT
-------
STATEMENT OF JAMES R. MAHONEY
Presented at the Scientific Seminar on Automotive Pollutants
Sponsored by the U. S. Environmental Protection Agency
Washington, D. C.
February 11, 1975
My name is James R. Mahoney. I am Vice President and Technical Director in
an environmental consulting firm with offices and laboratories in Massachu-
setts, Illinois, and California.
I am appearing as a member of the Panel on Emissions to Air Quality, con-
vened by the National Academy of Sciences. I will summarize the findings
of the Panel, and I will add some other comments based on information which
has recently become available. My colleague, Dr. George Hidy, who was
Chairman of the Panel, is unable to attend this hearing. He has submitted
a statement for the record and major portions of his written statement are
included in this presentation. My comments and recommendations on recently
available information represent the personal, professional opinions of
Dr. Hidy and myself. These comments will be identified separately from the
conclusions of the Academy Panel in the remainder of the presentation.
The Panel on Emissions to Air Quality was convened by the NAS/NAE Environ-
mental Studies Board as a part of a larger group to examine several aspects
of air quality and automobile emission control for the U. S. Senate Public
Works Committee. The Panel started its work in February, 1974, and completed
the draft report by July, 1974. Our report was submitted to the Senate Com-
mittee in early September of 1974*. The objectives of the Panel were to ex-
amine several aspects of the adequacy of existing emissions data, ambient
air quality measurements, and methods of predicting ambient air quality
from changes in emissions of transportation and stationary sources. The Panel
concentrated on the presently regulated pollutants, carbon monoxide, hydro-
carbons , nitrogen oxides and oxidant.
Regarding specifically the NO question, there are three aspects which must be
considered: First, the gas nitrogen dioxide (N02), a product of nitric oxide (NO)
oxidation, is regulated with an ambient air quality standard derived from evalu-
ation of health effects. Second, nitrogen dioxide plays a key role in the atmos-
phere as a precursor with Hydrocarbon vapors to form photochemical oxidant.
Third, NO are precursors in the formation of secondary aerosols, including
*It is available from the U. S. Government Printing Office as "National Academy
of Sciences/National Academy of Engineering Coordinating Committee on Air
Quality Studies, 'The Relationship of Emissions to Ambient Air Quality',
Volume 3" - Washington, D. C., 137 p.
-------
- 2 -
their water, ammonium and nitrate content. For these potentially hazardous
particulatc pollutants, no basis has been clearly established for governing
regulations. Control strategies of NO to meet the ambient air quality stan-
dards for NO and oxidants may not necessarily be the same, which creates a
need for optimization.
The principal conclusions of the Academy Panel are stated in the form of
answers to questions. I will summarize these conclusions with special rele-
vance to NO as responses to five questions.
First, "Are there nationwide emission data which accurately characterize
emission trends of NO ?"
The review by the Academy Panel indicated that there is considerable un-
certainty in the emissions data available for NO , particularly for short-
time resolution required for characterization of oxidant levels. Further-
more, there is little information on the long-term reliability of present
emission control hardware either on mobile or stationary sources.
Among information which has recently become available, just this month
the California Air Resources Board has made available a new research re-
port on emissions and control of NO in the South Coast Basin prepared by
D. R. Bartz et_ al. Emission factors were experimentally verified and
fluctuation in time and space we-re assessed. The maximum daily emissions
during December and January are 30% higher than annual average emission
rates. Forty-seven percent of the total is emanating from a limited area
in the S-W corner of the Basin. Unfortunately, concentration of power
plants and refineries is upwind of a substantial portion of the Basin.
Even if all mobile source emissions from this area were eliminated, the
localized stationary source emissions during stagnant conditions with
typical inversion heights were found to be sufficient to generate first-
stage N0_ alerts in the area.
In another report recently completed by George Hidy and several co-workers
for the California Air Resources Board, it was demonstrated that the atmos-
pheric conversion rates of both SO and NO emissions influencing the ac-
cumulation of particulate sulfates and nitrates may be greater in the South
Coast Basin than elsewhere. Trajectory studies also sponsored by the
California ARE indicate that emissions from the southwestern area could
be playing a major role in contributing to major and hazardous episodes. In
view of all this information, it seems that instead of devising control
strategies on concepts based on broad scale averaging, success is more
readily achievable by way of an approach which recognizes local and regional
variability in emission patterns. This is especially pertinent in view of
the differences between emission patterns in California and those in several
other parts of the country.
The second question is, "Are there nationwide air monitoring data which
adequately characterize air quality (with specific reference to NO hydro-
carbons and oxidants)?"
-------
- 3 -
The nationwide base of air quality to establish the history of urban and
non-urban concentrations of NO , hydrocarbons and oxidant since the mid-
1960' s is very limited and is variable in quality as a result of limita-
tions in instrumentation rind calibration methods. The data derived from
the 1). S, National Air Surveillance Network has been criticized for poor
quality and for limitations in accessibility. The observations from many
Federal, State and local agencies has been accumulating in the National Air
Data Bank, but little work has been done on careful, detailed analysis of
this collection because of a lack of accessibility and inadequate resources
of manpower and funding.
The data base that appears to be most useful for establishing trends in
NO and its impact on oxidant over the past ten years is that of the Southern
California area. Like other sets, these data have been criticized for un-
certainties in calibration. These uncertainties have just recently been
resolved by a special California ARE committee on which Dr. Peter Mueller,
a co-NAS panelist> also served. The actual monitoring data were obtained
by use of essentially the same instrumentation and operational methods for
several years so that correction by appropriate calibration factors now
yields an internally consistent perspective.
The third question is, "What apparent influence have control measures had
on emission trends?" "Are these emission trends reflected in ambient air
quality data?"
The methods initially used to control CO and HC emissions from motor vehicles
have led to an increase in emissions of nitrogen oxides. The results from the
monitoring in the Los Angeles area indicate that center city NOX has increased
with increasing emissions. In contrast, as a result of the interaction between
increased NO emissions and decreased hydrocarbon emissions, combined with
spatial changes in emission distributions, oxidant has decreased in central
Los Angeles but increased in areas downwind of the city, as is likely to be
documented in detail by Dr. Kinosian tomorrow. This has important implications
for monitoring site location. It is likely that maximum oxidant concentrations
should generally be sought downwind of urban centers. Trends on oxidant con-
centration are not presently well documented on a nationwide basis.
There is evidence in several areas of the United States area and the Eastern
Seaboard that oxidant levels are high (often close to Federal standard),
particularly in rural and suburban locations. There is speculation that
such concentrations are the result of (1) ozone formed in urban areas and
transported over long distances, or (2) of widespread increased NO emissions
combined with mixtures of anthropogenic and natural non-methane hydrocarbons
having a wide range of chemical reactivity in the atmosphere. The findings
of elevated oxidant concentrations in rural regions are very important.
These observations suggest that the transportation control strategies designed
to control elevated oxidant levels in urban areas may not be effective in
achieving compliance with the oxidant standard. As a personal recommendation,
I believe these findings should be examined very carefully, particularly in
-------
- 4 -
view of the major resource commitments and societal impacts associated with
many of the transportation control strategics proposed for urban regions
throughout the country.
The fourth question is, "What techniques are available to relate emissions
levels to ambient air quality; how accurate are the techniques, and what
techniques are recommended?"
Considerable progress has been made over the past five years in improving
air quality models for the reactive air pollutants. The newer prediction
schemes involve calculation explicitly of the interactions between geograph-
ical emission distributions, meteorological factors, and atmospheric chemical
processes. Because of concern for their accuracy and their, data requirements,
these methods have been used operationally only in a limited way to supplement
or supersede the classical rollback approach adopted several years ago for
setting emissions standards. There was disagreement in our panel about the
value of the simple rollback approach vs. diffusion-chemistry modeling within
its present state of development. In any case, the panel concluded that the
air quality modeling and data analysis has fallen far short of those needed
to establish confidence in our present national control strategy for NOX.
This is particularly distressing since policy decisions involving a national
investment of billions of dollars have relied on an engineering analysis in-
vestment of the order 1-5 million dollars. In the history of air pollution
control, few other technological changes have been implemented with such a
meager engineering background.
The final question concerns the motor vehicle emission standards. The Panel's
original charge was not to examine the adequacy of the current motor vehicle
standards. However, at the request of the parent coordinating committee,
we attempted to evaluate the adequacy of the standards to achieve the desired
air quality late in the study. This evaluation was done with very limited
resources in manpower and time.
On the basis of a review of existing rollback calculations, it appears that
the projected N0y emission standard may be more stringent than needed con-
tinuously to achieve the NO? ambient air quality standard for Los Angeles.
This conclusion must be qualified by three considerations: (a) the rollback
analysis requires that emissions from statipnary sources are reduced in pro-
portion to motor vehicle emissions, (b) rollback will be a satisfactory pre-
dicter of N02 if concentrations of this gas are proportional to NOX emissions,
and (c) there arc no substantial changes in geographical distribution of
sources. None of these requirements has been established in existing analyses
for any city in the United States.
The existing rollback calculations for oxidant reduction rely heavily on a non-
methane hydrocarbon (NM11C) vapor control approach. The role of NOX and the
changes expected by shifts in NOX/NMIIC ratio in oxidant formation are con-
siderably more uncertain than the projections for other air pollutants. The
existing analyses for the interactions of NOX and NM1IC inspire a low level of
confidence for achieving oxidant air quality using the present NO emission
projections.
-------
- 5 -
The national emission standards for motor vehicles NOX + NMHC may be overly
stringent in some geographical locations, but unsatisfactory for others,
particularly where significant photochemical smog is presently observed.
The geographical differences in control strategy have not been fully
exploited.
The conclusion of Dr. Hidy and myself is that there are compelling economic
arguments for reconsideration of the impact of emission standards on fuel
consumption and economy of transportation operations. The present NOX
emissions standards are inadequately justified on the basis of current
knowledge and experience in air quality data trends over the past ten
years. Control of pollution at the source remains the best means for air
quality improvement. However, it is necessary now to make the detailed
analytical effort to assess the degree of NOX control required for public
health and welfare commensurate with the economic investment required for
change. These engineering analyses will require at least a year to complete
and perhaps another year to digest by policy makers.
In closing, speaking for Dr. Hidy and myself, I wish to offer the following
specific recommendations:
1) Careful and detailed analysis of existing information on emissions
and ambient air quality be expedited, using air quality models
for potential NC>2 problems or photochemical oxidant problems in
key cities.
2) Present experimental studies in the Laboratory and in the field
be expedited to provide improved information to elucidate the
interactions between NOX and NMHC in the atmosphere for specific
engineeringapplications.
3) The observations of elevated oxidant concentrations in rural
areas be carefully examined to evaluate the potential effective-
ness (a lack of effectiveness) of transportation control strategies
for reducing similar oxidant concentrations observed in urban
centers.
4) Decisions on changing ambient air quality and emissions standards
for NOX must be tempered with consideration of the long-range
air conservation needs and goals of the United States.
5) The emissions standard for NOX not be changed at this time, but
implementation be delayed for one to two years pending the
receipt of results of ongoing investigations.
A delay in implementation of NOY emission standards proposed for 1977 may
be in order at this time to await the results of adequate studies now under-
way or those that should be initiated. However, such delays should be ac-
cepted knowing full well that air quality may deteriorate further in certain
.parts of the nation.
-------
J. DR. R.A. RASMUSSEN
RECENT FIELD STUDIES
-------
Description of the slides shown by R. A. Rasmussen at the Scientific
Seminar on Automotive Pollution in Washington, D.C. on February 12,
1975. Paper entitled "Recent Field Studies as regards the Role of NO
A
in the Oxidant and NCL Problem."
SLIDE l--Map showing sites in the U.S. where WSU field work has been
accomplished over the last two years. The major emphasis of these
different studies was to establish the background levels of natural
hydrocarbons, ozone, NO , CO, light scattering, condensation nuclei
A
counts and Freon-11. The support for studying the atmospheric burden,
reactivity and transport of trace gases at background levels were spon-
sored by the CRC-EPA CAPA-11 Project and separate EPA funding through
SLIDE #1
FIELD PROJECT SITES
NEW YORK CITY
k
-------
-2-
research grants 800670 and 802565 and EPA contract number 68-02-1232.
Today's presentation will be specifically focused on the measurements
and field experiments concerned with the role of NO in the oxidant and
A
N02 problem.
The principal investigators for the conduct and interpretation of
the results from the field studies to be discussed today were, in addi-
tion to myself, Professor E. Robinson and Drs. E. Grimsrud and H.West-
berg.
SLIDE 2, 3, 4 and 5--Kodachromes of remote rural areas in the northwest
or Upper State New York. These slides were shown to emphasize the
contrast between remote rural areas in the Pacific Northwest and non-
urban areas in the east. In the midwest and on much of the east coast
the rural areas available for study are in fact intercom*dor regions
between urban centers. Accordingly, the interpretation of the data from
these areas should consider this fact when evaluating the significance
of the rural sites used in these areas as representative of atmospheric
background values. Wooster, Ohio must be classed as a rural intercor-
ridor site and is mentioned specifically because it figures prominently
in the discussion on the role of rural NO values and oxidant formation.
A
Upper state New York, on the west side of Whiteface Mountain, is not an
intercorridor site in the same sense of Wooster, Ohio. In general, it
must be classified as rural but subject to occasional contamination from
long-distance transport.
-------
-3-
Also discussed with the slides were the observations for the limits
of the general levels of N0x in rural areas. At present, the observed
limits of background NO range from 5 to 20 ppb. Previous published
A
reports by Ripperton, Kornreich and Worth, in APCA, September 1970, also
reported the same range of values using wet chemical methods. A recent
report (#C-2-098) of the Air Resources Board from Sacramento, California
entitled Report on Air Quality from August 6 to August 18, 1973 in the
Sierra Valley, observed 5 to 16 ppb total NOX as the typical rural
background limit in this remote area.
Data that has been published on background NOX levels has been
mostly on N02, with little data on the levels of NO reported. However,
lH situ field measurements and laboratory experiments indicate that NO
is the major NOX emission and is primarily emitted by soil. This is
exclusive of the N20 emissions from soil. Agreement on natural diurnal
patterns of N0-N02 in rural areas have been difficult to confirm, both
in the ambient air and from the soil. The prime sink for the removal of
NO is generally believed to be ultimately the formation of nitrate
particulates.
SLIDE 6--Describes the objective and partial results from studying
oxidant formation in captured rural air samples studied in Ohio and
Idaho. The ozone formation in the bags was measured with and without
the addition of supplemental NO .
-------
-4-
SLIDE #6
OXIDANT FORMATION POTENTIAL OF NATURAL HYDROCARBONS
Objective
Determine how much natural materials contribute to the production
of photochemical oxidant.
Method
Collect rural air in transparent bags and irradiate these bag
samples with natural sunlight.
Results
1. Rural photochemical 0- formation: 20-60 ppb
2. 0- formation in excess of 80 ppb suspected of urban precursor
input.
3. Range of rural oxidant precursor levels; NMHC 0.2 to 0.4 ppmC,
NO 15-40 ppb.
A
4. Ozone formation at Wooster, Ohio—variable.
5. Ozone formation in Spring Valley, Idaho—consistent.
-------
CD
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NO N02 (ppb)
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Oj (ppb) NO N02 (ppb)
M A 01 OD N A 0»
O O O O O O OOP
RAOITION
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-------
-7-
SLIDE 10--Another set of graphs showing the same phenomenon for different
days.
I20_
OZONE FORMATION
RURAL BAG IRRADIATIONS
WITH AND WITHOUT ADDED NO
WOOSTER.OHIO 7/3/74
o
8
140
I20_
I00_
80
60_
40_
20
0.
SPRING VALLEY, IDAHO 8/28/74
WITHNO ADDED
10
I
11:30
TIME
230
-------
-8-
SLIDE 11--Reiterates the results, emphasizing that rural air has the
potential to produce 20 to 60 ppb of ozone from the irradiation of the
natural oxidant precursors present in the air samples studied. The
production of ozone levels in excess of 80 ppb, while possible from the
natural emissions, should be suspected of some anthropogenic contamination.
These experiment suggest that the initial levels of NO should be
/\
carefully inspected. Differences in the reactivity of the hydrocarbons
between Ohio and Idaho are indicated by the respective experiments.
Specifically, the Ohio rural air mass could be considered to represent a
spent air mass, since the addition of further NO did not immediately
A
activate further oxidant formation. The Idaho air samples, to the
contrary, demonstrated sufficient hydrocarbon reactivity to quickly
produce excess ozone compared to the nonsupplemented samples.
-------
-9-
SLIDE #11
OXIDANT FORMATION POTENTIAL OF NATURAL HYDROCARBONS
(Continued)
6. Effect of added NO (50 ppb) to air samples on 0- yield
X O
a. Wooster, Ohio—negative, retarded 0- formation.
b. Spring Valley, Idaho—positive, doubled 0., formed.
c. Both Wooster and Spring Valley had about the same HC/NO
/\
ratios.
7. a. Rural--Forest air with reactive HC like terpenes with
added NO produced excess ozone.
A
b. Adding NO to Wooster, Ohio, rural air did not produce
A
increased ozone.
8. Natural contribution versus urban contamination
a. Early morning rural air samples have an oxidant formation
potential.
b. Urban input into rural area is via direct ozone advection
to rural site or via precursors remaining in spent air
mass to subsequently form excess ozone upon irradiation.
Degree of hydrocarbon reactivity remaining in spent air
mass determines further oxidant yield.
-------
-10-
SLIDE 12--Illustrates the dependence of ozone formation or production in
the captured air samples on the initial NO levels. This relationship
^
again suggests the possibility of anthropogenic contaminants influencing
rural air masses exhibiting elevated ozone levels.
SLIDE
DEPENDANCE OF 03 PRODUCTION IN CAPTURED
AIR SAMPLES ON INITIAL [NOX]
_
ex
Q.
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LJ
tr
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z
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O
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140
120
100
80
60
40
20
0
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O
° 0
-
O
GL
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_
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_
iii
0 10 20 30 40 50
INITIAL NOX (ppb)
-------
SLIDE 13--Attempted through a listing of N09/N0 ratios to demonstrate the age or the youthful-
£• A
ness of the air masses studied. Typically, as NO is the primary source from both natural and
manmade emissions, the ratio of N02/NOX would qualitatively indicate the relative age of the air
mass through the respective NO-NO^ percentiles.
URBAN NO RATIO, INDEX OF AGE OF AIR MASS POLLUTANT BURDEN
6-9 A.M.
AVERAGE (PPB)
1 - 4 P.M.
AVERAGE (PPB)
NO
N02
N02/NOX
PHOENIX
88
41
.32
HOUSTON
88
15
.15
PORTLAND
120
25
.17
CANTON
33
42
.56
PHOENIX
24
13
.35
HOUSTON
66
17
.20
PORTLAND
25
14
.35
CANTON
10
18
.65
RURAL NO.
24-HOUR AVERAGES (PPB)
NO
N00
NEW YORK
10
2
MISSOURI
12
2
OREGON
13
4
-------
-12-
SLIDE 14, 15 and IB—Demonstrate that during a flight through Wheeling,
West Virginia on an overcast day that a bifurcated plume of NO was
/\
indicated by two discrete decreases in the background ozone levels
recorded. The NO values were measured in bag samples obtained in the
n
plume. The measurements indicated that the NO level was approximately
A
two times that of background, mid-40 ppb.
SLIDE #14
SOUTHBOUND
8 Ml S.E. of Whwllng
NORTHBOUND
II Ml. S.E. of WhMlIng
JULY 5
AFTERNOON FLIGHT PATH
TIME S 15 - 510
WhMlmg wuthbound 4 10
Morfonloon 4 30
WhMlmg northbound 4 50
WIND 340 of llmpn
WEATHER Cool with Rom
COMMENTS Numb«r« on oion«
concentration* in ppb.
Flight oltiludf -1,000
-------
SLIDE #15
-13-
JULY 5
AFTERNOON FLIGHT PATH
TIME 3:15 - 5.10
Wheeling southbound 4:10
Morgontown 4:30
Wheeling northbound 4 50
WIND 340 ot llmph
WEATHER Cool with Rain
COMMENTS Numbers are ozone
concentrations in ppb.
Flight altitude= -1,000
SLIDE #16
60-
70
SOUTHBOUND
8 Ml S.E. of Wheeling
NORTHBOUND
M Ml. S.E. of Wheeling
-------
-14-
SLIDE 17--Illustrate the same phenomenon for Canton, Ohio during an
early evening flight. The oxidant levels upwind of Canton were signifi-
cantly higher than those measured in the downwind plume of the city.
The transport of NO during the night for subsequent participation in
A
oxidant production the following (sunshine day) is recognized but not
fully appreciated.
SLIDE
SO 57 5J 6? 56\59 "*fi |\ S l-sn
, VI I I I Vl'jft «V^2 76 If?
JULY 25
EVENING FLIGHT PATH
TIME 7:50-9:00
WIND 070 ot 4mph
WEATHER Cloudy and Warm
COMMENTS Numbers are ozone
concentrations in ppb.
Flight altitude = I.OOO1-,
flown in counterclockwise
direction.
-------
-15-
SLIDE 18--A summary of a model for ozone formation that attempts to
assign descriptively and semi quantitatively limits to the components
responsible for the different origins of the ozone measured under well
mixed conditions for rural-urban-rural situations. The major point is
that stratospheric ozone may be responsible for 30 to 50 ppb of the
surface ozone measured over the continental U.S. This value has been
determined not only from ground measurements but from aircraft measure-
ments at and above the mixing depth of the surface air. Natural photo-
chemical production can add 20 ppb of ozone to this burden.
The impact of transported rural background ozone to the urban area
is considered in this model to be of no consequence since it is destroyed
in the NO shield at the urban boundary. However, Coffey and Stasiuk,
EST, January 1975, believe the contrary and have assigned a major
SURFACE LAYER OZONE CYCLE MODEL
STRATOSPHERIC
(TRANSPORT
NATURAL PHOTO
CHEM INPUT
20 ppb
10 ppb MIN CONC.
INPUT TO
+ 500 ppb
URBAN
PHOTO CHEM
DECAY OF
URBAN 0,
. LOSSES TO
GROUND AND
AEROSOLS
RURAL
COMPLETE
SCAVENGING
NO & AEROSOL
REACTIONS
URBAN
RURAL
-------
-16-
significance to the ozone transported into the urban area from the rural
environs.
The third phase of the model is descriptively and quantitatively
incomplete. This is because we do not know how far ozone per se is
transported or how far ozone precursors can travel and still exhibit a
significant effect on subsequent ozone production. Junge (1962, 1963)
has calculated, as regards the meteorological stratospheric-tropospheric
exchange process, that the transport time for ozone from the stratosphere
to the earth's surface is approximately two months. His calculations
indicated that ozone is not rapidly destroyed above the earth's surface.
These observations, plus the presence of ozone layers aloft over and
downwind of urban centers, substantiates its expected durability during
transport in advected air masses for 24-48 hrs.
Recently, Cleveland and Kleiner of Bell Laboratories have reexamined
the elevated oxidant problem at the rural Ancora site in New Jersey and
have concluded that the oxidant precursors from Camden, New Jersey and
Philadelphia, Pennsylvania are responsible for the elevated ozone levels
in Ancora, Mew Jersey. However, the effective distance in this specific
case is only on the order of 30 to 40 kilometers.
In conclusion, the impact of urban oxidant transport and associated
precursors on the order of distances of several hundred miles is not
known. Nevertheless, it is on this 'larger scale that our future atten-
tion should focus, as the importance of the transport of pollutant
burdens on an extra-regional scale becomes recognized.
-------
K. DR. THOMAS HECHT
MODELING EVIDENCE
-------
SMOG SIMULATION MODELS AND THEIR USE IN EVALUATING
AIR QUALITY CONTROL STRATEGIES
Thomas A. Hecht
Systems Applications, Incorporated
San Rafael, California 94903
In recent years, scientists have used many experimental methods to
investigate the effects of hydrocarbon and NOX emissions on ozone levels.
However, because of the complexity of the smog formation process, they are
turning more and more to modeling techniques as an additional means of
interpreting observations made in the laboratory and the field.
Using a general kinetic mechanism, we have mathematically simulated
smog chamber experiments to determine the dependence of predicted 03 levels
on the initial hydrocarbon concentration, the initial NO concentration, and
time [Hecht et a!., (1974)]. For these simulations, we assumed the following
conditions:
> The hydrocarbon concentration was 75 percent n-butane and
25 percent propylene.
> The NO levels were those specified in the figures dis-
cussed below.
> The initial N0? concentration was 0.10 ppm for all runs.
> The photolysis rate constant for N02 was 0.35 min'1.
-------
Figure 1 shows the time required for complete conversion of NO to
as a function of the initial concentrations of HC and NO. This conversion
is fastest under conditions of high HC and low NO levels, and it is slowest
under conditions of low initial HC and high NO concentrations. Because 03
accumulation is inhibited until NO reaches very low levels, Figure 1 sug-
gests that the time at which 03 formation occurs depends on the initial HC
and NO concentrations.
Figures 2 through 6 show lines of constant 03 at various times as a
function of initial HC and NO concentrations. Although high concentrations
of NO inhibit 03 formation after short simulation times (e.g., one or two
hours), 03 does accumulate eventually under most conditions. True suppres-
sion of 03 occurs only when all of the HC is consumed without a complete con-
version of NO to N02- Under such conditions, the [N02J|/[NO] ratio does not
reach a high enough level to sustain a significant 03 concentration. An
air quality control strategy based on substantial reduction in hydrocarbons
and lesser reductions (or even increases) in NO levels should be qualified
carefully. For example, the release of reactive organic material (e.g.,
from natural sources) into an aged parcel of air (which has been depleted
of HC from urban sources but which, as a result of reactions, also contains
a higher ratio of [N02]/[NO] than that present initially) could cause addi-
tional oxidation of NO. Consequently, very high concentrations of 03
could accumulate in rural or downwind areas. To prevent high 03 levels
downwind, air quality control standards should not permit NO emissions to
rise significantly.
-------
120
E
a.
a.
O
U
I
H
O
240
360
540
NOQ (ppm)
FIGURE 1. TIME OF THE NO PEAK (IN MINUTES)
-------
0.3
E
o.
Q.
O
O
I
H
O
.' 1.2
0.2
0.6
0.8
N0
FIGURE 2. LINES OF CONSTANT 03 (IN PPM)
AFTER 1 HOUR OF SIMULATION
-------
0.5
0.3
Q.
CL
O
O
X
o
h-
20
1.6
0.8
0.4
0.2
0
0.2
0.4 0.6
NOQ (ppm)
0.8
FIGURE 3. LINES OF CONSTANT 03 (IN PPM)
AFTER 2 HOURS OF SIMULATION
-------
0.2
FIGURE 4. LINES OF CONSTANT 03 (IN PPM)
AFTER 5 HOURS OF SIMULATION
-------
0.
CL
O
O
X
o
I-
1.0
N00 (ppm)
FIGURE 5. LINES.OF CONSTANT 03 (IN PPM)
AFTER 8 HOURS OF SIMULATION
-------
2.0
E
CL
a.
O
O
X
_J
<
1.6
1.2
0.8
0.4
0
0.2
0.4
0.6
0.8
NOQ (ppm)
FIGURE 6. LINES OF CONSTANT 03 (IN PPM)
AFTER 9 HOURS OF SIMULATION
-------
Like the results of smog chamber experiments, the simulations provide
only a limited picture of the actual atmospheric process. Therefore, we
are currently developing an airshed model (see Figure 7) that takes into
account the combined effects of the following:
> Emissions—from fixed and mobile sources—that are distrib-
uted in time and space across an air quality control region.
> Meteorology, including sunlight intensity, wind speed and
direction, mixing depth, and turbulence.
> Photochemistry.
The output of this model is predictions of pollutant concentrations as a
function of location and time.
Although airshed models have been used to examine the predicted effects
of proposed air quality control strategies [Reynolds and Seinfeld (1975)],
these simulation runs have been conducted primarily to demonstrate possible
applications of the model. Unfortunately, the use of the results of these
exercises is of limited value to policy-makers because of substantial uncer-
tainties in each of the following areas:
> The choice of worst-case meteorological conditions.
> The choice of initial and boundary conditions.
> The forecasting of emissions patterns and levels in
future years.
> The kinetic reaction model.
[See Roth (1974) for an overview and appraisal of existing models.]
-------
EMISSIONS
• MOBILE SOURCES
• STATIONARY SOURCES
METEOROLOGY
• WINDS
• INVERSION
• TURBULENCE
• SUNLIGHT INTENSITY
INITIAL CONDITIONS
BOUNDARY CONDITIONS
MODEL INPUTS
PHOTOCHEMISTRY
•KINETIC MECHANISM
^
MASS CONTINUITY EQUATIONS
•ADVECTION
•DIFFUSION
•REACTION
AIRSHED MODEL
PREDICTED CONCENTRATIONS
AS A FUNCTION OF
LOCATION AND TIME
MODEL OUTPUT
FIGURE 7. THE SAI AIRSHED MODEL
-------
n
If a thorough study of the HC-NOX oxidant problem were undertaken,
many of these uncertainties could be reduced. Although model predictions
would still have to be qualified, they would provide evidence that would be
useful in evaluating the effects of proposed emission standards.
-------
REFERENCES
Hecht, T. A., J. H. Seinfeld, and M. C. Dodge (1974), "Further Develop-
ment of Generalized Kinetic Mechanism for Photochemical Smog,"
Environ. Sci. and Technol., Vol. 8, p. 327.
Reynolds, S. D., and J. H. Seinfeld (1975), "A Study of the Possibility
of Meeting Ambient Air Quality Standards in the Los Angeles Basin,"
to be published in Environ. Sci. and Technol.
Roth, P. M. (1974), "Photochemical Air Pollution Simulation Models:
An Overview and Appraisal," Triangle Universities Consortium on
Air Pollution, University of North Carolina, Chapel Hill, North
Carolina (17-19 April 1974).
-------
Reprinted from ENVIRONMENTAL SCIENCE & TECHNOLOGY, Vol. 8, Page 327, April 1974
Copyright 1974 by the American Chemical Society and reprinted by permission of the copyright owner
CURRENT RESEARCH
Further Development of Generalized Kinetic Mechanism for
Photochemical Smog
Thomas A. Hecht and John H. Seinfeld1
Department of Chemical Engineering, California Institute of Technology, Pasadena, Calif. 91109 and
Systems Applications, Inc., San Rafael, Calif. 94903
Marcia C. Dodge
Chemistry and Physics Laboratory, Environmental Protection Agency, Research Triangle Park, N.C. 27711
• A generalized kinetic mechanism for photochemical
smog is formulated and tested. The most important fea-
ture of the mechanism is its general nature; that is, the
mechanism is applicable to a large number of hydrocar-
bons and, ultimately, the entire atmospheric mix. By de-
sign, the mechanism takes advantage of the common fea-
tures of hydrocarbon and free radical reactions to main-
tain at a minimum the number of species included while
at the same time retaining a high degree of detail, espe-
cially as concerns the chemistry of the inorganic species.
The mechanism is tested using fi-butane-NO*, propylene-
NO*, and w-butane-propylene-NOj; smog chamber data at
13 different sets of initial reactant concentrations and a
wide variety of hydrocarbon to NO* ratios. The predicted
effect of initial reactant ratios on ozone formation is in
agreement with the data that were analyzed.
A large number of experimental programs have been
carried out over the past two decades with the aim of in-
creasing our knowledge of the process by which photo-
chemical smog forms. In 1961 Leighton published an ac-
curate and, it now appears, reasonably complete descrip-
tion of the photochemistry of air pollution. Since that
time, additional kinetic and mechanistic studies of ele-
mentary reactions thought to be important in smog for-
mation have served to further refine our understanding of
the overall process. By 1969 the picture had become suffi-
ciently complete to enable formulation of kinetic mecha-
nisms for the mathematical simulation of smog formation
observed under controlled laboratory conditions.
The object of developing a kinetic mechanism for pho-
tochemical smog is to enable the prediction of both smog
chamber reaction phenomena and atmospheric reaction
phenomena. There are some general considerations impor-
tant in developing such a mechanism. First, the mathe-
matical description of the mechanism (in terms of the
number of species included) must not be overly complex,
as computation times for the overall urban simulation
model within which the mechanism is to be embedded are
likely to be excessive. On the other hand, an overly sim-
plified mechanism may omit important reaction steps,
and thus be inadequate to describe atmospheric reactions
over a range of conditions. A major requirement, then, is
that the mechanism predict the chemical behavior of a
complex mixture of many hydrocarbons, yet that it in-
clude only a limited degree of detail. Thus, the mecha-
nism must strike a careful balance between compactness
of form and accuracy of prediction.
1 To whom correspondence should be addressed.
A kinetic mechanism, once developed, must be vali-
dated. This procedure is commonly conceived as consist-
ing of two parts: validation in the absence of transport
processes and validation in their presence. In practical
terms we are speaking, respectively, of comparison of the
model's predictions with data collected in smog chamber
experiments and with data collected at contaminant mon-
itoring stations in an urban area. When we speak of vali-
dation of a kinetic mechanism here, we are referring to
the comparison between predictions and experiment
based on smog chamber studies.
It is only in the last 10 years that general kinetic mech-
anisms have been postulated to describe photochemical
smog chemistry. The mechanisms that have been pro-
posed can be classified as either specific (written for pho-
tooxidation of a specific hydrocarbon) or lumped (written
for one or more species involving lumped reactants) and
include the following:
Specific mechanisms
Westberg and Cohen
(1969)
Hecht and Seinfeld
(1972)
Nikietal. (1972)
Demerjian et al. (1974),
Isobutylene
Propylene
Propylene
Propylene, trans-2-butene,
isobutene, re-butane,
and formaldehyde
Lumped mechanisms
Eschenroeder and Mar-
tinez (1972)
Wayne et al. (1971)
Hecht and Seinfeld
(1972)
Specific mechanisms, while often quite complex (e.g.,
the Hecht and Seinfeld propylene mechanism contains 81
reactions), can play an important role in helping elucidate
the fundamental chemistry of the photooxidation process.
However, for none of the specific mechanisms listed above
has there been reported a program of validation over a
range of initial reactant concentrations. Thus, all five can
only be considered at this point as detailed chemical spec-
ulations.
The chief advantage of generalized mechanisms is the
compact mathematical representation that lumping af-
fords. Unfortunately, each of the three mechanisms suffers
several shortcomings. In particular, they share the fol-
lowing two disadvantages:
The representation of the atmospheric hydrocarbon mix
is oversimplified. The individual hydrocarbons present in
polluted air basins differ widely in reactivity, and the
"average" reactivity of this mixture of organics changes
continuously throughout the day. An attempt to describe
Volume 8, Number 4, April 1974 327
-------
this complex behavior with one or two lumped classes of
hydrocarbons in a kinetic mechanism may be inadequate.
The predictions generated are strongly dependent upon
the specification of uncertain parameters. Both the EM
and HS mechanisms contain generalized stoichiometric
coefficients that represent the number of free radicals
formed in a given reaction. These parameters are difficult
to specify a priori; hence, confidence in the predictions of
these mechanisms for cases not explicitly validated is
poor. The Wayne et al. mechanism, based on the photoox-
idation of propylene, assumes that a mixture of atmo-
spheric hydrocarbons behaves as a mixture of propylene
and a second hydrocarbon of lesser reactivity than propyl-
ene. Again it is impossible to determine a priori the rela-
tive proportion of these two hydrocarbon species in an at-
mospheric mixture.
In the time since the EM, HS, and Wayne mechanisms
were developed, significant advances have been made in
our knowledge of the mechanisms and rate constants of
the individual reactions contributing to smog formation.
It therefore appears that a new kinetic mechanism can
now be developed that avoids many of the shortcomings of
the three existing mechanisms. In particular, a new mech-
anism should be rigorous in its treatment of inorganic
reactions (because of their importance), sufficiently de-
tailed to distinguish among the reactions of various classes
of hydrocarbons and free radicals, free of poorly defined
adjustable parameters, and as compact as possible.
The object of this paper is to formulate and present val-
idation results for a new mechanism that meets the above
requirements. In the following section we first list the im-
portant inorganic reactions in photochemical smog, and
then present a systematic analysis of hydrocarbon and
radical lumping. This is done to illustrate the various lev-
els of complexity that might be included in a mechanism
and to identify the decisions that must be made in con-
structing a lumped mechanism. Based upon our conclu-
sions and realizing the shortcomings of the preceding
mechanisms, we then propose a new lumped mechanism.
Finally, we present extensive validation exercises using
smog chamber data collected by the Environmental Pro-
tection Agency (EPA).
Reaction Classen in Photochemical Smog
We present a very brief survey of the important inor-
ganic and hydrocarbon reactions in the photochemical
smog system. Numerous reviews of these reactions are
available (Leighton, 1961; Altshuller and Bufalini, 1971;
Johnston et al., 1970), so that we will consider here only
those elements of chemistry important to the development
of a kinetic mechanism.
Inorganic Reactions. The reactions in the system of
NOi, air, HaO, and CO have received much attention. A
survey of rate constant values reveals the first 21 reactions
in Table I to be of greatest importance.
Hydrocarbon Reactions. We first wish to make a fun-
damental distinction between types of mechanisms, based
on the treatment of hydrocarbon and free radical reac-
tions. The first type is that written for the photooxidation
of a specific hydrocarbon. This is the type we ordinarily
envision, one in which each species in each reaction repre-
sents a distinct chemical entity. The second type is the
lumped mechanism, one which contains certain fictitious
species that represent entire classes of reactants.
In many chemical systems the number of species is
often extremely large. In addition, when many species are
present, they often span a significant range of reactivity.
Certain species may not be present in measurable concen-
trations, and many rate constants may not be known ac-
curately. As a result, quantitative predictions of reaction
rates may be highly uncertain. In such a case, one is un-
able to deal with each species separately; rather, one must
partition the species into a few classes (called lumped
classes), and then consider each class as an independent
entity. This idea has been employed to a limited extent in
the three lumped mechanisms cited above.
In the atmospheric photochemical smog system the
large number of organics and free radicals makes lumping
a necessity in developing a practical kinetic mechanism.
Considering the types of reactions involving organics and
free radicals in photochemical smog, we can identify two
different criteria by which groups may be established.
First, lumping may be carried out by organic and free
radical function group classification, such as olefins, aro-
matics, and paraffins, and alkyl, acyl, and alkoxyl radi-
cals. Second, lumps may be established on the basis of re-
activity with certain key species, for example 0, Os, OH,
and NO, regardless of functional group. The one guideline
is that lumping should be carried out such that a balance
is achieved between accuracy of description of the under-
lying processes and compactness of the mechanism. Let us
consider the two alternatives just mentioned. We begin
with a discussion of organics.
In a complex mixture of hydrocarbons, such as is found
in the atmosphere, each hydrocarbon may potentially
react with 0, Os, and OH, yielding varying numbers and
types of free radicals depending on the particular hydro-
carbon. Our objective is to form a relatively small number
of groups of lumped hydrocarbon species, call them HCi,
HC2, ..., HC^r, which will, in some sense, represent the
mixture of hydrocarbons present in the atmosphere. We
shall examine the two basic criteria: lump organics based
on class (olefins, aroma tics, paraffins, aldehydes) and
lump organics based on reactivity with individual oxi-
dants, such as 0, Os, or OH.
Consider the first criterion, the lumping of organics by
class. Although the mechanisms for the oxidation of these
four classes of organics by O, OH, and Os have not yet
been resolved in detail, the likely product distribution
are:
Olefins + <0
Aromatics +
Paraffins +
0 -^ R- + RCO
*.'
Aldehydes +
RCO + RO- + Aldehyde
- R-
R- + OH-
not important
R- + H20
R- + OH-
not important
R- + H,0
RCO + OH-
not important
RCO 4- H20
RCO + H- + CO
Since OH has an odd number of electrons and O-atoms
and Os each have even numbers of electrons, when these
species attack hydrocarbons (with even number of elec-
trons) the OH must produce an odd number of free radi-
cals (normally one) while the 0-atom and ozone must pro-
328 Environmental Science & Technology
-------
duce an even number of free radicals (normally either zero
or two). Thus, the number and type of free radical prod-
ucts in each step shown above can be specified with some
certainty. On the other hand, within each lumped species
there is a distribution of rate constants for the reactions
with O, Oa, and OH. For example, there is a wide spectrum
of rate constants for olefin-O reactions. Therefore, the rate
constants for O, Os, and OH reactions with each lumped
species must be taken as average values that reflect in
some manner the relative amounts of different individual
species within each lumped species.
Since the differing reactivities of the individual compo-
nents comprising a grouping will lead to their disappear-
ance at different rates throughout the course of photoox-
idation, the effective rate constants for reaction of the
lumped species with 0, Os, and OH must also vary during
the course of the reaction. In summary, then, lumping of
hydrocarbons by class will allow rather definite assign-
ment of stoichiometric coefficients but will necessitate
rate constants which reflect the average reactivity of the
individual species within each lumped species as a func-
tion of time.
We now consider the second criterion, the lumping of
hydrocarbons by reactivity. The first question we face in
this case is—reactivity with respect to what? The three
obvious choices are reactivity (rate constant) with O, Os,
OH. Although the relative importance of 0, Os. and OH
attack depends on the hydrocarbon (e.g., uiefms react
with Os but other classes of organics do not), computed
rates of hydrocarbon disappearance generally correlate
more closely with the OH rate than with the other two
rates (except at the very beginning of the photooxidation
when the O atom rate is predominant). Suppose, for ex-
ample, that we elect to divide the hydrocarbon mixture
into three classes based on their OH rate constant:
HO, k <1000ppm-1min-1
HC2 10005000ppm-1min '
On this basis each group would contain all classes of hy-
drocarbons, with the rate constants for reaction with OH
defined by the composition of the grouping. Rate con-
stants for reaction with 0 and Os, however, would not
necessarily correlate with the grouping based on the OH
rate and would have to be determined in a manner similar
to the case of lumping with respect to hydrocarbon class.
However, during the main course of the reaction, the hy-
drocarbons within each group would be consumed at
roughly the same rate so that the reactivity and stoichi-
ometry of the group would not be expected to change with
time.
While rate constants can be determined relatively accu-
rately, the number and types of free radical products
within each lumped group would vary because each group
would contain hydrocarbons of all classes. This would ne-
cessitate the adoption of stoichiometric coefficients which
reflect the individual makeup of each lumped group.
To illustrate the forms of lumped reactions following
the scheme based on OH reactivity, let us assume we have
N groups, as, for example, the three defined above, HCi,
HC2, HC3. The reactions with O, O3, and OH can be
written-
HC, +
(0 -^ a,,R- + tt,2RCO + a,
I- 0,2RO- + ,
(5,/vHC.\
lOH- -^ 7,,R' +
i " 1,2, ...,N
where a,Jt 0,j, 6U, and y,j are stoichiometric coefficients
which reflect the individual compositions of the HCi, i =
1,2, . .., N For example, if HCi consisted entirely of ole-
fins we might expect an = «,2 = 1 and ntta - 0- Thus the
stoichiometric coefficients are not to be considered as
freely adjustable parameters, but rather as parameters
whose values are fixed because of the choice of hydrocar-
bons comprising each lumped species HC,.
Let us summarize the advantages and disadvantages of
the two alternative hydrocarbon lumping criteria. For
lumping by hydrocarbon class, we list two advantages:
The definition of the lumped species depends only on the
type of hydrocarbon (i.e., olefin, aromatic, or alkane).
Since the products of 0, Os, and OH reactions with vari-
ous hydrocarbon classes are essentially the same within
each class, the number and type of free radical products
would be well defined for each class (assuming the prod-
ucts are indeed known).
Two disadvantages are: The rate constants for reaction
with O, Os, and OH vary for the individual components in
each lumped species necessitating the computation of
"average" rate constants. The relative distribution of the
hydrocarbons in each lumped class will change throughout
the course of the photooxidation such that "average" rate
constants chosen on the basis of the initial composition
may not reflect accurately the reactivity of the lumped
species at later times.
For lumping by hydrocarbon reactivity (with OH), two
advantages are: The definition of the lumped species
would correspond closely to the role played by the indi-
vidual hydrocarbons comprising it in the conversion of NO
to N02. Since the reactivity of each lumped species is
roughly invariant in time, rate constants and stoichiomet-
ric coefficients for the lumped OH—HC reaction would
not require adjustment during the course of the reaction.
Two disadvantages are: Each grouping would contain hy-
drocarbons of all classes, making it difficult to account for
the distribution of free radicals produced as a result of
reactions with 0, Oa, and OH. In the late stages of the
photooxidation, ozonolysis reactions may assume a level of
importance equal to or greater than that of OH (if olefins
still are undepleted). A lumping on the basis of OH reac-
tivity may no longer reflect the reactivity distribution of
the total mixture at that stage.
Upon consideration, lumping by hydrocarbon class
seems to offer several advantages over lumping by reactiv-
ity. First, fewer stoichiometric coefficients need be speci-
fied in the former method, thereby leading to fewer un-
specified parameters. Second, rate constant values of hy-
drocarbon-OH reactions are in many cases not known pre-
cisely enough to permit a clear distinction to be made
among hydrocarbons as to reactivity class. Third, atmo-
spheric measurements generally are reported by hydrocar-
bon class, and lumping by class would enable direct com-
parisons of mechanism predictions with atmospheric data.
For these reasons, we will subsequently employ hydrocar-
bon lumping by class in our development of a general
mechanism.
Free Radical Reactions. As we have just seen, the
reactions of O, Os, and OH with hydrocarbons yield the
following classes of free radicals: R-, RCO, RO-, where R
can be a hydrogen atom, an alkyl group, or an alkyl group
containing an alcohol functional group. We must now
trace the most likely reactions of these species with the
others in the system. Consider R-, RCO, and OH- as typ-
ical products. Both R- and RCO will most probably react
with 02 by R. + 0) __* R0j.
RCO + 0,
RCOO-
0
Volume 8, Number 4, April 1974 329
-------
These peroxy radicals will undergo a variety of reactions,
the most important of which are with NO and NOj
ROO- -I- NO —- NO, + RO
ROM) + NO -—• NO, + KCO-
II II
o o
RCOO- + NO, —* RCOONO,
II II "
o o
The two new radicals formed will then probably react in
the following manner:
RO- + 0, —* ECHO + H02-
—- R- + C02
o
The likely history of typical alkyl and acyl radicals in
chain propagation reactions can thus be depicted as
RCO
0,
RCO
H02"
OH-
HC
We see that, during the lifetimes of R- and RCO, many
molecules of NO can be converted to NOz (of course, each
step in the sequence competes with other propagation and
termination reactions). When NO concentration becomes
sufficiently low, peroxyacyl radicals may react with NOz
to give peroxyacyl nitrates. The alkoxyl radicals may also
react with N02 at this point to yield alkyl nitrates. A rad-
ical recombination reaction between ROj and NOz to
form an alkylpernitrate, ROONOz, provides another pos-
sible fate for peroxyalkyl radicals in smog. We are not
aware of any smog chamber studies in which ROONOa
has been detected (in quantities similar to RONO or
RON02). The product may be unstable or its rate of for-
mation may be slow. Owing to these considerations, we
have chosen not to include the reaction in the formulation
of the mechanism.
Having discussed the reactions in which radicals may
participate, we now must consider the manner in which
free radicals are included in the mechanism. The two ex-
tremes in the representation of radicals are the specific
mechanisms in which no lumping is used (each radical
species is a distinct entity) and the EM and HS mecha-
nisms cited earlier in which all free radicals were com-
bined into a single species. The first limit is unrealistic
from a computational point of view and also in light of our
incomplete knowledge of free radical rate constants. In
contrast, the other limit does not afford us the ability to
distinguish the effect of different hydrocarbon mixtures on
the concentration/time behavior of a specific system.
Therefore, we seek a basis for the lumping of radicals that
lies somewhere between these two extremes.
A detailed study of free radical reactions in photochem-
ical smog (Leighton, 1961) indicates that radicals of simi-
lar structure usually undergo similar reactions at roughly
comparable rates. This suggests that the most detailed
representation of radicals would involve having separate
species for each radical class. The classes of radicals in-
volved have already been introduced. They are
R- Alkyl
RCO Acyl
ROO • Peroxyalkyl (including HO2 •)
RCOO-
T
Peroxyacyl
Acylate
RO- Alkoxyl (including OH-)
Above we listed several of the most probable reactions in-
volving these radicals that would take place in a hydro-
carbon-NOj-air system. We also illustrated typical histo-
ries of acyl and alkyl radicals in such a system. Based on
these likely reactions, we wish to propose a lumping
scheme which is consistent with the probable chain
lengths of each radical (and thus the conversion rate of
NOtoN02):
Alkyl Radicals. We assume that alkyl radicals quickly
add Oj to form peroxyalkyl radicals. Thus ROO-, and not
R-, need specifically enter into the mechanism.
Acyl Radicals. We assume that acyl radicals, like alkyl
radicals, quickly add Oj to form peroxyacyl radicals.
Thus, RCOO-, and not RCO, need specifically enter into
0
the mechanism.
Peroxyalkyl Radicals. These radicals undergo reaction
with NO to form NOa. Thus, they remain in the mecha-
nism. Because of the importance of HOa-, we remove it
from the class ROO -, and treat it as a separate species.
Peroxyacl Radicals. Like ROO-, these can react with
NO; these radicals also enter into a reaction with NOz to
form stable peroxyacyl nitrates. They are included in the
mechanism.
Acylate Radicals. These radicals result from reaction of
NO and peroxyacyl radicals. We assume that they decom-
pose quickly to form alkyl radicals (hence, peroxyalkyl
radicals) and COj. Thus, they are not included in the
mechanism.
Alkoxyl Radicals. These radicals result from reaction of
peroxyalkyl radicals with NO and from ozonolysis of ole-
fins, and enter into reactions with NO and NOz forming
stable products. The most important member of this class
is the hydroxyl radical. Because of the extreme impor-
tance of OH, it seems desirable to remove OH from the
RO class and retain each in the mechanism .
Summarizing, the radicals that appear to be of suffi-
cient importance to warrant separate treatment are OH-,
H02-, ROO- (excluding HO2-), RCOO-, and RO- (ex-
cluding OH- )
Formulation of a Lumped Mechanism
The purpose of this section is to develop a lumped ki-
netic mechanism based on the combined conclusions
reached thus far. In particular, we will employ the lump-
ing scheme suggested for hydrocarbons and the categori-
zation of radicals just presented. We choose the classes:
HCi = olefins, HCa = aromatics, HCa = paraffins, and
HC* = aldehydes, the reactions of which are given by
steps 22-30 in Table I.
We note that in reaction 24, OH adds to the double
bond of olefins forming an alcohol-like free radical,
RCHCH,
OH
which we have assumed to react in the same fashion as an
alkyl radical. This is not exactly true, as this free radical
decomposes in a different manner from R- in subsequent
reactions. Specifically, RCHOHCH2 is thought to react to
form one additional aldehyde (Heicklen et al., 1969). We
have, therefore, included HC4 as a product of the OH —
HCi elementary reaction to correct for this anomaly. In
330 Environmental Science & Technology
-------
reaction 30, if HC« is HCHO, the initial product is HCO,
which decomposes to H- + CO, subsequently yielding
HO2 , rather than the peroxyacyl radical.
The parameters a and /3 can be specified with a high
degree of confidence. The first, a, is the fraction of car-
bons attached to the double bond in a monoolefin which
are not terminal carbons on the chain; thus, it can be
specified a priori. Consider the O — HCi reaction for
propylene and 2-butene which, respectively, contain ex-
ternal and internal double bonds.
/
0 + CH;1CH— 'CH/
CHO
+ CH3
0
0
0 + CH3CH— CHCH3HCH3CCH,CH3|-*
0 CHaC- +
0
If we now assume that alkyl and acyl radicals react rapid-
ly with Oj and that CHO decomposes into CO + H02 in
the presence of Oa, these reactions can be rewritten in our
generalized notation as
R02- + HO/
0 + CH3CH=CH, 0, + M
0, + NO > NO, + 0,
Important reactions of 0 with inorganic species
4
0 + NO + M > N02 + M
0-fNO, >NO + 0,
6
0 + NO, + M > NO. + M
Chemistry of N08, N205, and HNO,
O, + NO, » NO, + 0,
NO,+ NO >2NO,
9
NOj+NO, >N,0S
N,O. >NO,+ NO,
11
N,O, + H,O »2HNO,
Reactions of HNOa with inorganic species
12
NO + HNO, > HNO, + NO,
13
HNO, + HNO, > H,0 + 2ND,
Chemistry of HNO,
NO + NO, + H,O > 2HNO,
2HNO, » NO -f NO, f H,0
16
HN02+ hi. >OH + NO
Important reactions of OH with inorganic species
OH + NO, »HNO,
18
OH + NO + M > HNO, + M
19
OH + CO + (0,) > CO, + HO,
Oxidation of NO by HO,
20
HO, + NO » OH + NO,
Smog
Photolysis of H,0,
H,0,
21
>20H
Organic Oxidation Reactions: HCi = olefins, HC, = aromatics,
HC, = paraffins, HC4 = aldehydes
Hd + 0 » ROO + aRCOO + (1 - a)HO,
O
23
HCt + 0, » RCOO + RO + HC4
HCi -f OH -
HC, + O-
HC, + OH -
HC, + 0 -
HC, + OH -
HC4 + hr -
HC« + OH -
24
26
27
28
29
• ROO + HC,
ROO + OH
ROO + H,0
ROO + OH
• ROO + H,O
• /3ROO + (2 - 0)HO,
30
- (3)HO, + H,0
• /3RCOO
Reactions of organic free radicals with NO, NO,, and 0,
ROO + NO > RO + NO,
32
RCOO + NO + (O,) » ROO + NO, + CO,
0
33
RCOO + NO, > RCOONO,
o 4
34
RO + 0, > HO, + HC4
35
RO + NO, > RONO,
RO+NO >RONO
Other peroxy radical reactions
37
HO, + HO, > H,0, + 0,
38
HO, + ROO » RO -(- OH + 0,
2ROO > 2RO + 0,
Volume 8, Number 4, April 1974 331
-------
The reactions of the inorganic species and the radical
species ROO-, RCOO-, and RO- have already been out-
0
lined. We then assemble all the inorganic, hydrocarbon,
and free radical reactions into a generalized lumped
mechanism, as is summarized in Table I.
The final issue to be considered with regard to this
mechanism is how it is employed to represent such behav-
ior as that of a complex mixture of several olefins or sev-
eral aromatics. In the mechanism in Table I, all olefin
reactions are represented by HCi, all aromatic reactions
by HC2, and so forth. Consider a mixture of M olefins, the
oxidation reactions of each of which are represented by
reactions 22-24, with a different rate constant and value
of a for each olefin. We assume that we know the initial
concentrations of each olefin as well as the rate constants
for reactions 22-24. It is clear that if we wish to represent
these M olefins, call them OLi, OLa, ..., OLw, by the sin-
gle lumped species HCi,
[HC,] - 230L,]
We must account for the change in the lumped rate con-
stants, kn, kts, and ku, and a with time as the more re-
active constituents of HCi are depleted more rapidly than
the less reactive ones. To compute the change in the rate
constants with time, the relative amounts of high- and
low-reactivity contributors to HCi must be determined.
This need indicates that more information than merely
[HCi] must be available.
Let us assume that the M olefins have been ordered
such that their reactivities obey the sequence OLi > OLz
> ... > OLjtf. We can then employ lumping based on OH-
reactivity by representing these M olefins by P lumped
olefins, defined as indicated below:
°H[
OLJ1
OL
J}[HC«]
•' •
[OL,]
Since each group HCjj is chosen on the basis of original
olefins whose reactivities are close in value, the rate con-
stants for reactions 22-24 for each HCi; would be con-
stant, perhaps set equal to the weighted average of the
values for the olefins in that group. Then since all mem-
bers of a group HCij would presumably react at compara-
ble rates, the rate constants corresponding to HCij would
not change in time.
This sublumping scheme would apply equally well to
the other classes, HC2, HC3, and HC*. The choice of P,
the number of sublumps, within each class would be
made on the basis of the individual components and their
relative reactivities. In the testing of the mechanism to be
reported shortly, only mixtures containing a single species
in a particular organic class were considered. Thus, the
sublumping scheme was not needed, and the rate con-
stants for reactions 22-24 (olefins) 27 and 28 (paraffins),
and 29 and 30 (aldehydes) were those of the particular
species.
In representing atmospheric mixtures, our knowledge of
the individual organic species present is usually not suffi-
cient to necessitate the use of sublumping within the four
categories of olefins, aromatics, paraffins, and aldehydes.
In that case, it must at present suffice to represent all the
organics in a class by one species in that class whose reac-
tivity is roughly the average of those in the class. Results
of the use of the mechanism in Table I to represent atmo-
332 Environmental Science & Technology
spheric chemical reactions in the Los Angeles basin will
be reported in a subsequent communication.
In the computational evaluation of the mechanism we
have assumed four species to be in pseudosteady state: O,
OH, RO, and N03. The validity of this approximation for
the first three species has been established by comparing
the concentrations predicted both in the presence and ab-
sence of the pseudosteady state approximation. These
comparisons indicate that maximum discrepancies in con-
centrations are of the order of 0.01% over a 400-minute
simulation, thereby establishing the validity of the ap-
proximation for 0, OH, and RO. We were not able to per-
form an identical test for NOS, as the NOS concentration
predicted at the very beginning of the simulation was neg-
ative when the NOs concentration was represented by a
differential equation. (This reflects the fact that N03
forms chiefly after the NOz peak by reaction 7. As there is
no Oa present initially, numerical roundoff error at the
first time step results in negative NOa concentrations.)
Concentrations predicted for later times appear, however,
to confirm the validity of the steady state approximation
forNO,.
Comparison of Lumped Mechanism to the Simplified HS
and EM Mechanisms
Given the lumped mechanism, we can now examine the
assumptions inherent in the HS and EM mechanisms.
Both the HS and EM mechanisms have provisions for two
lumped hydrocarbon species, usually specified to be of
"high" and "low" reactivity. In each, all free radicals are
combined into the single species ROj.
The main result of the reaction of atomic oxygen with
lumped species in these two mechanisms is the formation
of peroxy radicals, represented by
HC + 0 —* «R02
Notice that production of hydroxyl radicals from O-atom
reactions with paraffins and aromatics has been neglected
in this step.
The ozone-hydrocarbon reactions are assumed to yield
peroxy radicals and aldehydes,
o3 + HC —- >RO2 + VRCHO
In the new mechanism it is assumed that a peroxyacyl
and an alkoxy radical form rather than the peroxyalkyl
radical.
The OH-hydrocarbon reactions are assumed to yield per-
oxy radicals and a small quantity of aldehydes,
HC + OH- —* (3RO2- + ff'RCUO
The remaining organic reactions are
R02- + NO —* N02 + (OH-
R02 + N02 —- PAN
By comparison of the first reaction with the more correct
reactions,
ROO- + NO —- N02 4- (OH- + (1 - t)RO
RCOO- + NO
0
NO, + ROO-
we see that regeneration of ROO- has been neglected in
the conversion of NO to NOz by peroxyalkyl and peroxya-
cyl radicals. Thus, the t in the HS and EM mechanisms
cannot be interpreted as the fraction of RO2- that is
H02- as it is in the more correct reactions, but rather
only as an empirical parameter. As a result, the original
stoichiometric coefficients a, ft, and y cannot be assigned
the actual values that would be expected from the chem-
istry of the individual species. Rather, the a, 0, y, and t
become a set of parameters governing the chain length
-------
(the average number of free radical reactions, or propaga-
tion steps, that occur as a result of each initiation reac-
tion). This lack of direct correspondence of the general-
ized stoichiometric coefficients in the HS and EM mecha-
nisms to actual stoichiometric coefficients is the chief
weakness of the two mechanisms. By virtue of its in-
creased detail, the new lumped mechanism in Table I cir-
cumvents this shortcoming as the stoichiometries are de-
rivable directly from the underlying chemistry of each ele-
mentary reaction.
Data Base Sources of Experimental Uncertainty
The significance of the validation results for a kinetic
mechanism is to a large degree dependent upon the diver-
sity and reliability of the experimental data base. We
were fortunate in being able to obtain chamber runs for
this study involving both low- and high-reactivity hydro-
carbons, as well as a simple mixture. Moreover, the ratio
of HC/NO* was varied over a wide range for each reactant
system. In this section, we describe the data base used for
validation purposes. We examine in some detail the im-
portance of accurately specifying certain experimental
variables, notably light intensity and water vapor concen-
tration. We discuss the degree to which wall effects may
influence observed chamber results. Finally, we comment
on the accuracy and specificity of the analytical instru-
mentation used to monitor pollutant concentrations and
on the reproducibility of the experiments.
Data Base. The data used in this validation study were
collected by the Chemistry and Physics Laboratory of
EPA. It is comprised of three hydrocarbon-NO, systems:
n-butane-NOx at three diiferent HC/NO* ratios, propyl-
ene-NO, at four different HC/NOX ratios, and n-butane-
propylene-NOjt at six different HC/NO* ratios. All but
two of the chamber runs were made between February
and May of 1967. The remaining two runs (457 and 459)
were carried out in March 1968. The initial conditions for
the experiments are given in Table 13.
Light Intensity. Radiation intensity is one of the most
important parameters in a smog chamber experiment, for
it governs the photolysis rate of NC>2 (reaction 1), the
reaction which initiates and sustains the smog formation
process. In the period during which the experiments were
performed it was customary to represent the light intensi-
ty by a fictitious first-order rate constant for NOz decay,
ka. It can be shown that
*'
Thus, ka is, in essence, a pseudorate constant repre-
senting the combined rates of all NOa reactions in an oxy-
gen-free atmosphere. Unfortunately, the use of ka leads to
difficulties, since the combined reaction it represents is
Table II. Initial Conditions Associated with
Experimental Chamber Data
EPA run (NO>V (NOV (n-ButaneV (PropylcneV
306' 0.03 0.30 1.60
314 0.02 0.29 3.17
345 0.12 1.28 3.40
318 0.06 1.12 0.51
325 0.04 0.32 0.45
329 0.06 0.26 0.24
459 0.06 1.14 0 78
307 0.05 1.23 3.06 0.36
333 0.08 1.25 3.41 0.23
348 0.08 1.23 3.39 0.44
349 0.03 0.31 3.25 0.44
352 0.07 0.27 3.29 0.26
457 0.05 1.11 3.29 0.81
' Initial concentrations in units of parts per million (ppm).
10.12 ppm of aldehyde also present initially.
not first order. Recently, Holmes et al. (1973) have shown
how ki, the desired rate constant, can be determined di-
rectly from NC>2 decay data in an atmosphere of NZ and
Oj, thereby eliminating entirely the necessity to analyze
data in terms of ka. However, since the only available
data for light intensity in the experiments considered here
were reported in terms of ka, we have no choice but to es-
timate k-i from ka. The value of ka was determined by the
investigators to be 0.40 min-1, but was not redetermined
during the 10-month period over which the data were
taken. We have assumed, in accordance with the results
of Schuck et al. (1966), that ki ss % ka, or 0.266 min-i.
Finally, we have estimated that, due to inaccuracies in
the determination of ka, in the factor % relating ka to fej,
and in the estimation of irradiation intensity, ki could be
in error by more than ±20%.
Water Vapor in Chamber. Another parameter that is
thought to be important in smog chamber runs is the
water concentration. Water enters into the smog kinetics
via reactions 11 and 14, nitric and nitrous acid produc-
tion. The latter is important since photolysis of nitrous
acid produces OH radicals that, in turn, initiate further
reactions. The humidifier control of the inlet air stream to
the chambers was set to generate 50% relative humidity at
75°F, but, during very cold, dry weather, relative humidi-
ties of only 30% were achieved. The humidity of the inlet
air stream was checked only once or twice during the 11-
month study.
Wall Effects. An effect of particular concern in smog
chamber studies is the influence of surfaces on chemical
dynamics, and thus on observed reaction kinetics. Of
major importance in this regard is the possibility of direct
loss of material to the walls. Of lesser concern is the possi-
bility of chemical interactions occurring between adsorbed
pollutants and material in the gas phase. Although it is
possible that some low-reactivity organics such as carbox-
ylic acids and ketones can be found on the walls as a re-
sult of hydrogen bonding with adsorbed water, we focus
our attention in this discussion on species which have
been clearly identified on the surfaces of a small smog
chamber (Gay and Bufalini, 1971)—nitric acid, nitrates,
and nitrites. We begin then by discussing the heterogene-
ous reactions of the most important oxides of nitrogen,
NO and NOa. In the process, we also give attention to
various mechanisms that might account for the appear-
ance of HNOs as a product of these reactions.
NO and NOy. Even in so-called dry systems it is rea-
sonable to assume that an adsorbed layer of water will be
found on the walls of the smog chamber. This is certainly
the case for the experiments under consideration in this
study, as the chamber was intentionally humidified dur-
ing all runs. Thus, one possible explanation for the ap-
pearance of nitrate and nitrite on the walls would be dis-
solution of NO and NO2 in the adsorbed water layer. Ni-
tric oxide can be eliminated in this regard because of its
extremely low solubility in water; NOz, however, disso-
ciates in water by the following reactions (Hill, 1971):
6N02 + SHjO 3F=* 3HNOij + 3HN02
3HN02 *=* HN03 + 2ND + HjO
The rate of loss of NO2 in this manner is dependent upon
the amount of water adsorbed, the rate of dissolution of
NO2, and the magnitude of rate constants for the disso-
ciation reactions. In the experiments under consideration,
however, N02 losses via this mechanism can be neglected
because, within experimental error, the small amounts of
NO* lost up to the time of the NO2 peak can be ascribed
to sampling and dilution. We might then conclude that no
significant amounts of NO or NO2 were lost directly to the
Volumes, Number4, April 1974 333
-------
walla during the smog chamber experiments.
NtOt. After the NOj peak occurs, and as Os begins to
accumulate, NzOs forms by the reactions
N02 + 03 =i=fc N03 + 02
N03 + N02 =f=t N205
will undergo hydrolysis to form nitric acid by the
reaction
NA + H20 — - 2HNOa
If the hydrolysis takes place in the adsorbed layer of water
on the wall, HNOa will form directly on the walls. How-
ever, both the water concentrations in smog chambers
(63% relative humidity (RH) at 25°C is equivalent to
20,000 ppm HaO], and the rate constants for the primary
reactions in nitric acid formation in the gas phase (Table
III) are large enough that the loss of NO* after the NOz
peak may be fully ascribed to the formation of nitric acid
in the gas phase. Assuming this reaction takes place ho-
mogeneously, therefore, should not lead to errors as a re-
sult of neglecting heterogeneous reactions.
HNOa. Nitric acid has a high vapor pressure and thus it
is unlikely that straight dissolution in water is important
as a mechanism by which nitric acid in the gas phase
reaches the walls. However, interaction of gaseous nitric
acid with specific substances absorbed in the wall layer
could account for the observed loss of nitric acid from the
gas phase. Unfortunately, detection of HNOs in the gas
phase has until now proved to be a difficult task, perhaps
because the acid is lost to the walls of the sampling tube.
Other Chemical and Catalytic. Effects of Walls. It
would, of course, be highly desirable to expand our under-
standing of the degree to which interactions occur be-
tween adsorbed pollutants on the walls and material in
the gas phase. Unfortunately, our knowledge concerning
such phenomena is limited, and we can only speculate.
We thus offer the following two comments:
We expect that the rate of heterogeneous oxidation of
NO in chambers is small. For example, in a chamber
characterization experiment, 1.6 ppm of NO was irradiat-
ed in air for 6 hr. At the end of that period only 19% of
the NO had been oxidized to NOa. We believe that this
figure represents an upper limit for the rate of nonphoto-
chemical oxidation of NO. It is expected that, for a cham-
ber having a small surface to volume ratio, such as the
one employed in the experimental studies utilized in this
effort (approximately 1 ft"1; the chamber has an internal
surface area of 330 ft2 and a volume of 335 ft3), the influ-
ence of the walls on NO oxidation rates is small. The ef-
fect would be additionally reduced in reactant systems for
which the time to the NOz peak is relatively short (i.e., 2
hr or less).
As we concluded earlier, we expect that the presence or
absence of wall effects would result in no detectable dif-
ferences in the rate of formation of HNOs, largely because
of the strong tendency of NzOs to hydrolyze in the gas
phase at the water concentrations used during these ex-
periments. Similarly, whether HNOa is formed in the gas
phase, subsequently migrating to the wall, or whether it is
formed directly on the wall, it is unlikely that the site of
hydrolysis will have much of an effect on the observed
chemistry, since subsequent reactions involving HNOs ap-
pear to be of minor importance.
We conclude, based on the preceding discussion, that
no significant amounts of NO and NOa are lost directly to
the walls and that the loss of ^Os and HNOs to the walls
should not alter the observed photochemistry. However, it
is not possible at this time to ascertain the degree to
which the walls might accelerate the oxidation of NO.
Estimates of Experimental Error. Before comparing
model predictions with experimental observations, we
334 Environmental Science & Technology
should establish both the accuracy and the precision of
the measurements. Inaccuracies in determining concen-
trations are largely attributable to lack of specificity or
accuracy in analytical procedures, particularly in the in-
strumentation used to monitor concentrations during the
course of an experiment. Imprecision is detected through
the poor repeatability of an experiment, the results of
which may or may not be accurately determined. There
may be a wide variety of causes of imprecision, some of
which may also be attributable to instrumentation prob-
lems.
Accuracy of Analytical Instruments. The four pollutant
species of primary importance in our modeling efforts,
NOj, NO, Os, and hydrocarbons, were all measured using
standard instrumentation and techniques as pointed out
in the following four paragraphs:
Hydrocarbons were determined individually by gas
chromatography; the accuracy of these measurements is
estimated to be ±10% at a concentration level of 1 ppm.
Oxidants were measured using two independent tech-
niques: the Mast Ozone Meter and neutral KI analysis.
Corrections to KI readings were required to account for
interferences due to PAN and NOj. Despite the correc-
tions the KI measurements exceeded the Mast readings by
an average of 50%. Since the KI technique is probably the
more accurate of the two procedures (Kopczynski, 1972),
we have validated the mechanism using the results of the
KI analyses.
Oxides of nitrogen were sampled manually into fritted
bubblers containing Saltzman reagent. Nitric oxide was
oxidized to form N02 by reaction with sodium dichro-
mate. It has been estimated that this conversion is almost
100% efficient (Kopczynski, 1972).
Peroxyacetyl nitrate was separated on a borosilicate
glass column packed with polyethylene glycol on Gas
Crom Z and analyzed by an electron capture detector.
In general, the accuracy of these various measurements
is a function of the concentration level of the pollutant
being measured. Accuracy is poorest over the low concen-
tration range.. For example, at concentrations of N02
below 0.15 ppm, concentrations can be determined no
more accurately than ±20%. At the higher concentrations
encountered as the reaction proceeds, the accuracy of the
readings improves substantially.
Repeatability of Experimental Runs. Because replicate
runs were made for only four of the experiments used for
our validation studies, we have been unable to calculate a
meaningful statistical measure of the reproducibility of
the experiments. But, in those few instances for which a.
replicate run was available, the agreement between the
two sets of data was quite good. Our impression of the
chamber data is that, in spite of the lack of recalibration
of the light intensity and chemical analyzers, the data are
in general reproducible, were carefully taken, and are as
suitable as any currently available for validation purposes.
Validation of 39-Step Lumped Mechanism
Evaluation of the lumped kinetic mechanism in Table I
consists of: obtaining estimates of the various input pa-
rameters to the mechanism—the reaction rate constants,
parameterized stoichiometric coefficients, a and ,8, initial
concentrations of reactants, and average dilution rate con-
stants; carrying out sensitivity studies for these parame-
ters—i.e., establishing the effect of controlled variations
in the magnitude of the various parameters on the con-
centration-time profiles for NO, N02, Os, and hydrocar-
bons; and generating concentration-time profiles for the
various reactant mixtures using the specified initial condi-
tions. These predictions are then compared with experi-
-------
mental results to assess the "goodness of fit."
In the first part of this section we discuss the basis for
selection of the input parameters. In the second portion of
the section, we present the validation results for each of
the three hydrocarbon systems studied. Results are sum-
marized as a series of plots displaying both predicted and
measured concentrations.
Estimation of Parameters. Prior to obtaining kinetic
information from the lumped mechanism, all known pa-
rameters must be specified and uncertain parameters esti-
mated. The input parameters to this mechanism include
the rate constants, parameterized stoichiometric coeffi-
cients, initial react ant concentrations, and average loss
rates of the reactants and products due to sampling.
Hate Constants. While the kinetic mechanism is written
in a general fashion, we have striven to formulate it in
such a way that all important features of the detailed
chemistry are retained. Thus, our goal has been to include
each elementary reaction thought to contribute to the
overall smog kinetics.
Several papers have been published in the past three
years which review the vast literature dealing with kinetic
studies relevant to the reactions now thought to be impor-
tant in smog formation. These include the detailed mod-
eling study of Demerjian et al. (1974), the atmospheric
chemistry and physics assessment in Project Clean Air
(Johnston et al., 1970), and the detailed modeling study of
propylene conducted by Niki et al. (1972). Their recom-
mended values for the rate constants of the individual
reactions incorporated in the lumped mechanism, as well
as more recent or different determinations, are presented
in Table III, along with values which we used in our vali-
dation studies. Note that, for each reaction, the validation
value of the rate constant is within the range of values
recommended by these three groups or other individuals.
For some reactions a considerable span exists between the
lowest and highest "best" estimate of the rate constants
(e.g., the formation of PAN by reaction 33). This general-
ly indicates that the rate constant has not yet been pre-
cisely determined experimentally. In such instances pa-
rameter values have usually been reached by analogy to
similar reactions with known rate constants.
Parameterized Stoichiometric Coefficients. As we noted
earlier, two parameterized stoichiometric coefficients
must be specified. Since the only olefin which we are con-
sidering in this validation study is propylene, a terminal
olefin, a is always equal to %. The value of ft depends
upon the fraction of total aldehydes formed during an ir-
radiation that is not formaldehyde. The approximate
values of |9 for the three systems validated are
System
n-Butane-NO*
Propylene-NO*
ra-Butane-Propylene-NO*
ft
0.75
0.50
0.63
The accuracy of these values is probably no better than
±20% because the ratio of formaldehyde to higher al-
dehydes fluctuates somewhat during an irradiation, all the
higher aldehydes may not have been detected with the an-
alytical instruments, and the accuracy of the analytical
techniques used to determine aldehydes in this study is
poor. This uncertainty, however, introduces no substantial
Table III. Validation Values of Rate Constants and Their Comparison with Recommended Values of
Other Investigations
Reaction Validation'value Demerjian etal. (1974) Johnston et al. (1970) Niki etal. (1972) Others
1 0.266min->
2 2.0 X 10-' ppm~s min-1
3 20.8
4 3.5 X 10-' ppm-J min-1
5 1.38X10'
6 2.2 X 10-' ppm~' min-'
7 4.6 X 10-»
8 1.5 X 10*
9 4.5 X 10"
10 1.5xlO'min-i
11 1.0X10-'
12 2.5 X 10-'
13 0.2
14 2.1 X 10-' ppm-2 min-1
15 4.5
16 1.3 X 10~2 min-1
17 1.5 X 104
18 1.2x10"
19 2.5 X 10s
20 7.0 X 102
21 1/250 k, min-1
22 6.8 X 103
23 1.6 X 10-J
24 2.5 X 10'
25 1.07X102'
26 3 X 10-''
27 6.5 X 10'
28 3.8 X 10"
29 2.5 X 10-" min-'
30 2.3X10*
31 9.1 X 10s
32 9.1X102
33 1.0X102
34 2.4 X 10~2
35 4.9 X 10s
36 2.5 X 102
37 5.3 X 10''
38 1.0X10'
39
l.OX 102
2.0 X 10-'
2.3 X 101
3.4 X 10-"
8.1 X 10J
2.2 X 10-'
0.48 1.1 X 10-1
0.66-1.47 X 104
6.8 X 10'
1.5 X 10'
2.5 X 10-3
<4.3 X 10-«
<4.5
1/4 X k,
>1.5 X 10*
0.8tJ7
2.5 X 102
2.0 X 102
1/160kt
6.8 X 10J
1.5 X 10~2
9.4 X 103
3.2 X 10'
6.4 X 10s
0.4-2.5 X 10~3
2.2 X 10'
9.1 X 102
4.7 X 102
4.9 X 102
2.4-5.6 X 10"2
3.0-4.9 X 102
2.0-2.5 X 102
5.3 X 10J
1.0 X 102
1.0 X 10-
Depends on experimental system
2.3 X 10-5 2.2 X 10-*
2.9X101 2.9x10'
2.5 X 10~3
8.1 X 103
1.1 X 10-'
1.5 X 10'
4.5 X 103
1.4X 101
3.0 X 10-'
6.9 X 10-o
1/10 X ki
1.5 X 10"
2.2 X 102
3.7-4.4 X 103
0.9-1.6 X 10~2
1.07 X 102
0.16-6.5 X 10'
5.7 X 10s
5.3X103
1.1 X lO'1
1.5X 10'
4.4 X 103
1.4 X 101
1.5 X 10-«
3.6X10-"
2.8 X 10~»
1/2000 k,
6.0 X 103
2.1 X W
2.6 X 102
2.9X 102
4.4 X 10!
1.7 X 10~!
2.5 X 10'
1/1000 k;
2.3 X 10'
2.9 X 102
1.5 X 103
2.2 X 10'
4.4 X 10~3
2.9 X 10J
9.9 X 102
5.3 X 10J
5.3 X 103
4.4 X 103
20.8'
1.38X10"
4.6 X 10-"
<2X10-S"
2.5X10-'"
<0.2/
7.0 X 102»
1/250 fc, •
6.0 X 103*, 3.8 X 10"
Volume 8, Number 4, April 1974 335
-------
impediment to the validation effort since variations in ft
over the extremes of the uncertainty bounds have little
effect on the predictions of the decision variables by the
kinetic mechanism.
Validation Results. Validation exercises have been car-
ried out for each of the sets of experimental data given in
Table II. Because of space limitations we cannot present
all the results here. Thus, we show only a representative
sample of the validation results. The results are depicted
in Figures 1-9.
§,00
OJO
020
010
200 3OO
TIME (MINUTES)
Figure 4. Comparison of observed and predicted concentrations
for EPA run 459
100 200 300
TIME (MINUTES)
Figure 1. Comparison of observed and predicted concentrations
for EPA run 306
060
0-0.45
0-
O
<030
O
§015
O
EPA 325
* PROPYLENE
a NO
°N02
• PAN
_ 250
S
1
S
200 300
TIME (MINUTES)
400
200
TIME (MINUTES)
Figure 5. Comparison of observed and predicted concentrations
for EPA run 307
Figure 2. Comparison of observed and predicted concentrations
for EPA run 325
0 451
2
a
o
z
o
100 200 300
TIME (MINUTES)
400
100 2OO
TIME (MINUTES)
Figure 3. Comparison of observed and predicted concentrations
for EPA run 329
Figure 6. Comparison of observed and predicted concentrations
for EPA run 333
336 Environmental Science & Technology
-------
100 200 300
TIME (MINUTES)
Figure 7. Comparison of observed and predicted concentrations
for EPA run 348
£075
100 ZOO 300
TIME (MINUTES)
Figure 8. Comparison of observed and predicted concentrations
for EPA run 349
100 ZOO 3OO
TIME (MINUTES)
Figure 9. Comparison of observed and predicted concentrations
for EPA run 352
The data base provided for the validation studies fulfills
many of the important requirements that one would wish
to place on it. The concentration levels of the hydrocar-
bons, nitrogen oxides, and oxidants are representative of
those observed during smoggy days in Los Angeles. A vari-
ety of hydrocarbon systems have been studied; high- and
low-reactivity hydrocarbons are represented in the data
base as are single reactants (n-butane and propylene) and
a binary mixture. Initial conditions for the runs cover a
broad range of hydrocarbon to nitrogen oxide ratios. This
is a particularly important property of the data base if the
validated mechanism is to be part of an urban simulation
model that will be used to evaluate proposed alternative
control strategies. On the whole, the accuracy and preci-
sion of the measurements are adequate, although there
are a number of important exceptions, which we will men-
tion shortly.
While the data base possesses many desirable attrib-
utes, its shortcomings must be noted as well, for these de-
termine the limits within which the model may be tested.
We have mentioned the most notable deficiencies of the
data base at one point or another in earlier sections. We
summarize them here with two basic comments:
(1) Inaccuracy in measurement and analytical proce-
dures. As noted earlier, Mast and KI readings were badly
discrepant, initial N02 was imprecisely determined, and
light intensity was not known with sufficient accuracy.
Also NO and NOz determinations were inaccurate at low
concentrations.
(2) Lack of measurement of certain species, in the gas
phase and on the wall. Efforts should be made to try to
monitor nitric and nitrous acid concentrations in future
studies.
Turning now to the results of the validation efforts, we
make a number of observations. We have been able to
demonstrate that, in general, there is good agreement be-
tween" predicted and measured concentrations. More spe-
cifically, the mechanism has shown good qualitative and
quantitative agreement with observed values of the time
of the NOz maximum and final ozone levels reached for
three different hydrocarbon-NO* systems and for a wide
range of hydrocarbon to NOX ratios. We must emphasize,
however, that substantial uncertainties in the magnitude
of light intensity (and thus the photolysis rates of NO2,
HNOa, and RCHO) as well as in the values of measured
concentrations of hydrocarbons, NO, N02, and Oa limit
the possibilities for critically testing the adequacy of the
mechanism with the data used.
The rates of oxidation of n-butane and propylene pre-
dicted by the mechanism match the data uniformly well
over the full range of initial concentrations studied. Also,
the predicted rate of oxidation of NO and the time to the
N02 maximum agree well with the data. An initial con-
centrations of NO* greater than 1 ppm, however, the rates
of Os accumulation and N02 oxidation are predicted to be
more rapid than observed (e.g., EPA runs 307, 333, and
348). Under these conditions, the predicted rate of accu-
mulation of NOz and the magnitude of the NO2 maxi-
mum were less than the corresponding experimental
values. We are unable to account fully for these dis-
crepancies, but a partial answer might lie in reactions in-
volving HNOs that have not yet been detailed or are of
greater importance than they are now thought to be. An-
other possible explanation is that interferences by HNO2
and HNOa in the N02 measurements led to artificially
high values for NO2.
In those experiments in which more than 0.5 ppm NO
was present initially, an asymptotic level of Os was not
Volume 8, Number 4, April 1974 337
-------
achieved during the irradiation. Thus, we can only judge
the predicted onset of Oa accumulation which was, in gen-
eral, in good agreement with the data. A true Oa maxi-
mum was achieved in a few of the runs (e.g., 306, 325,
329, and 349) and the predicted Oa maxima were for the
moat part within the uncertainty bounds of the data. PAN
validation data were available for only three sets of exper-
iments, runs 325, 329, and 459. For the first two of these
runs the predicted PAN concentrations are in good agree-
ment with the data; for run 459, however, the predicted
onset of PAN formation occurs too early and the levels
reached are high when compared with the data.
As is apparent from the results, the data and predic-
tions are not always in good agreement for all species over
the full period of the irradiation. These discrepancies can
be attributed to at least five possible sources of uncertain-
ty:
The mechanism may be incomplete. It has been our in-
tent to include every reaction presently thought to be im-
portant to explaining smog formation in the lumped
mechanism. In the future, new reactions may be discov-
ered and/or previously unsuspected products of elementa-
ry reactions may be found.
The lumping process may introduce error. For example,
we have assumed that the CHaCHCHzOa- radical (prod-
uct of the OH-propylene reaction) reacts in the same fash-
ion as the CHsCH2CH202- radical. To the extent that the
reactivities of these species are different, errors will be in-
troduced into the predictions.
There are uncertainties in the experimental data used
for validation.
Chamber effects (such as surface effects) which are not
accounted for in the model are potential sources of dis-
crepancy.
Not all of the rate constants are known with a high de-
gree of certainty. Indeed, for a few of the reactions no ex-
perimental determination has yet been made of the rate
constants. For the cases of those reactions for which sever-
al determinations of the rate constants have been carried
out, there is often poor agreement between the various es-
timated values.
As a consequence of these uncertainties, we have not
yet reached the point in model evaluation where we are in
a position to quantitatively assess the "goodness" of the
proposed mechanism, or for that matter, to draw unequiv-
ocal qualitative conclusions regarding its merits. Yet, the
mechanism appears capable of predicting the concentra-
tion-time behavior of a variety of reactant systems over a
wide range of initial conditions. Clearly, however, a con-
siderably more accurate and complete data base is re-
quired if the adequacy of the lumped-mechanism is to be
critically evaluated.
Effect of Initial Reactant Ratios on Ozone Formation
A well-documented characteristic of the photochemical
smog system is that the maximum concentration of ozone,
for a series of experiments in which initial hydrocarbon or
NO* is held fixed, increases, goes through a maximum,
and then decreases as the initial hydrocarbon to NO* con-
centration ratio is decreased (Haagen-Smit and Fox, 1956;
Stephens et al., 1956; Korth et al., 1964; Hamming and
Dickinson, 1966; Romanovsky et al., 1967; Altshuller et
al., 1967; Glasson and Tuesday, 1970; Dimitriades, 1972).
(We cite the study of Dimitriades, although, from irradia-
tion of auto exhaust, Dimitriades did not observe a maxi-
mum in the oxidant dependence on NO* within the range
of [HC]/[NOX] ratios studied.) While this phenomenon
has been verified experimentally, no kinetic mechanism to
date has been shown to be capable of predicting this be-
havior. Therefore, an important test of the validity of a
kinetic mechanism is its ability to reproduce the effect of
varying initial hydrocarbon to NO* ratios on oxidant for-
mation.
Isopleths of maximum ozone concentration predicted by
the mechanism in Table I as a function of total initial hy-
drocarbon concentration and initial NO concentration are
shown in Figure 10. The hydrocarbon mix used in generat-
ing Figure 10 consisted initially of 75% n-butane and 25%
propylene. Further, 0.10 ppm of NOa was chosen initially
in each case, so that the total initial NO* is the sum of
the indicated initial NO concentration and 0.10 ppm. The
ozone values in Figure 10 are the maximum values predict-
ed over 8 hr of irradiation. For all cases in which [HC]o/
[NOjtjo < 6, the ozone concentration had its largest value
at the end of the eight hour simulation. The smallest
ozone maxima are predicted either under conditions of
high initial hydrocarbon and low NO* or low initial hydro-
carbon and high NO (not NOz). In the former case, high
levels of ozone cannot accumulate since the NO* is rapid-
ly removed as stable products. In the latter case, high ini-
tial levels of NO inhibit the formation of ozone over the
long incubation period during which NO is oxidized to
N02. Furthermore, if the initial [HC]/[NO*] ratio is suffi-
ciently low, little ozone will be able to form even at very
long irradiation times; for, during that period, the hydro-
carbon will be substantially oxidized to stable products.
The general behavior depicted in Figure 10 matches closely
that observed experimentally (Korth et al., 1964; Roma-
novsky et al., 1967; Altshuller et al., 1967; Glasson and
Tuesday, 1970; Dimitriades, 1972).
As noted, the results shown in Figure 10 are based on the
study of an initial hydrocarbon mixture of fixed composi-
tion, 75% ra-butane and 25% propylene. However, it is also
important to determine the effect of alterations of the
composition of the initial hydrocarbon mixture on the
quantity of ozone formed. Figure 11 shows the maximum
ozone concentration predicted for an 8-hr simulation as a
function of the composition of an initial hydrocarbon mix-
ture of n-butane and propylene at [N0]o = 0.40 ppm and
[N02]o = 0.10 ppm. We see that reduction in the olefin
fraction of the mixture results in a substantial decrease in
the amount of ozone formed. The reduction in ozone level
is particularly effective between 0 and 10% olefin. Levy
and Miller (1970) experimentally investigated this same
issue through the study of organic solvent-NO* mixtures
and observed general behavior similar to that shown in
Figure 11. In their study, n-octane and m-xyiene were used
as the low- and high-reactive species, respectively. They
0 3 0.4 0.5
NO (PPM)
Figure 10. Isopleths of predicted maximum ozone concentration
achieved during an 8-hr Irradiation of various mixtures of n-
butane, propylene, and NO
Initial concentration of NO: equal to 0.1 ppm
338 Environmental Science & Technology
-------
0.50
PROPYLENE FRACTION OF INITIAL
HYDROCARBON MIXTURE (PROPYLENE
PLUS n-BUTANE)
Figure 11. Maximum predicted ozone concentration achieved
during an 8-hr irradiation of an initial mixture of [HC]o = 0.80
ppm, [NO]o = 0.40 ppm, and [NO2Jo - 0.10 ppm for various
Initial mixtures of n-butane and propylene
found that a reduction in the m-xylene to 3% of the sol-
vent mixture resulted in a 32% reduction in the amount of
ozone formed from that for a 50-50% mixture. Increasing
the m-xylene fraction to 8% resulted in a sharp increase in
the ozone level to 92% of that in the 50-50% mixture.
Point A on Figures 10 and 11 indicates the approximate
composition of the Los angeles atmosphere in 1969. At
this point the ozone levels lie close to the "ridge" of ob-
served maximum values. While reductions in either or
both the hydrocarbon and NO emission levels can be ex-
pected to result in decreased ozone levels, it appears that
hydrocarbon reductions will be more effective in reducing
ozone formation because the surface of ozone levels de-
clines more steeply in the direction of decreasing hydro-
carbons at fixed NO than in the direction of decreasing
NO at fixed hydrocarbon. Furthermore, a simultaneous
reduction in both hydrocarbon and NO emissions will not
be as effective as either of these other two routes. Finally,
we see that reduction in the olefin (high reactive) fraction
in the atmosphere may also provide an effective abate-
ment strategy.
Conclusion
Based upon our results (Figures 1-9) and the principles
of formulation, the kinetic mechanism developed here ap-
pears to hold substantial promise for incorporation in
urban simulation models. The mechanism describes the
important inorganic chemistry in detail, yet minimizes
the overall number of reactions by taking advantage of the
general behavior of specific groupings of similar hydrocar-
bons and free radicals. Further, the mechanism is free of
arbitrarily assignable stoichiometric coefficients. Thus,
the new lumped mechanism represents a reasonably rigor-
ous, yet manageable, description of the photochemistry of
air pollution.
Acknowledgment
Appreciation is extended to Karl Westberg for many
helpful comments on this work.
Literature Cited
Altshuller, A. P. Bufalini, J. J., Environ. Sci. Technol. 5, :!9
(1971).
Altshuller, A. P., Kopczynski, S. L., Lonneman, W. A., Becker,
T. L., Slater, R., ibid., I, 899 (1967).
Bufalini, J. J., Gay, B. W., Jr., Kopczynski, S. L., ibid , 5, 333
(1971).
Davis, D. D., Wong, W., Payne, W. A., Stief, L. J., "A Kinetics
Study to Determine the Importance of HOj in Atmospheric
Chemical Dynamics: Reaction with CO," presented at the
Symposium on "Sources, Sinks, and Concentrations of CO and
CH4 in the Earth's Environment," St. Petersburg Beach, Fla.,
August 1972.
Demerjian, K. L., Kerr, J. A., Calvert, J. G., "The Mechanism of
Photochemical Smog Formation," in press (1974).
Dimitriades, B., Environ. Sci Technol., 6, 253 (1972).
Eschenroeder, A. Q., Martinez, J. R., Aduan. Chem., 113, 101
(1972).
Gay, B. W., Jr., Bufalini, J. J., Environ. Sci. Technol., 5, 422
(1971).
Ghormley, J. A., Ellsworth, R. L., Hochanadel, C. J., J. Phys.
Chem., 77,1341 (1973).
'Glasson, W. A., Tuesday, C. S., Environ. Sci. Technol., 4, 37
(1970).
Greiner, N. R.,J. Chem. Phys., 53,1070(1970).
Haagen-Smit, A. J., Fox, M. M., Ind Eng. Chem., 48, 1484
(1956).
Hamming, W. J., Dickinson, J. E., J. Air Pollut. Contr. Ass., 16,
317(1966).
Hecht, T. A., Seinfeld, J. H., Environ. Sci. Technol., 6,47 (1972).
Heicklen, J., Westberg, K., Cohen, N., in "Chemical Reactions in
Urban Atmospheres," C. S. Tuesday, Ed., American Elsevier,
New York, N.Y.,1%9.
Hill, A. C., J. Air Pollut. Contr. Ass., 21, 341 (1971).
Holmes, J. R., O'Brien, R. J., Crabtree, J. H., Hecht, T. A.,
Seinfeld, J. H., Environ. Sci. Technol., 7, 519 (1973).
Jaffe, S., Ford, H. W., J. Phys. Chem., 71,1832 (1967).
Johnston, H. S., Pitts, J. N., Jr., Lewis J., Zafonte, L., Motters-
head, T., "Atmospheric Chemistry and Physics," Project
Clear Air, Task Force Assessments, Vol. 4, Univ. of California,
1970.
Kopczynski, S. L., private communication, Environmental Pro-
tection Agency, Research Triangle Park, N.C., 1972.
Korth, M. W., Stahman, R. C., Rose, A. H., Jr., J Air Pollut
Contr. Ass., 14, 168 (1964).
Leighton, P. A., "Photochemistry of Air Pollution," Academic
Press, New York, N.Y., 1961.
Levy, A., Miller, S. E., "Role of Solvents in Photochemical Smog
Formation," Report 799, Battelle Memorial Institute, Colum-
bus, Ohio, 1970.
Morris, E. D., Jr., Niki, H.,J. Phys. Chem., 75, 3640 (1971).
Morris, E. D., Jr., Niki, H., ibid., 77,1929 (1973).
Niki, H., Daby, E. E., Weinstock, B., Aduan. Chem., 113, 16
(1972).
Romanovsky, J. C., Ingels, R. M., Gordon, R. J., J Air Pollut.
Contr. Ass., 17, 454 (1967).
Schuck, E. A. Stephens, E. R., Schrock, P. R., ibid., 16, 695
(1966).
Stephens, E. R., Hanst, P. L., Doerr, R. C., Scott, W. E., Ind.
Eng. Chem., 48, 1498 (1956).
Wayne, L. G., Weisburd, M., Danchick, R., Kokin, A., "Final
Report-Development of a Simulation Model for Estimating
Ground Level Concentrations of Photochemical Pollutants,"
System Development Corp., Santa Monica, Calif., 1971.
Westberg, K., Cohen, N., "The Chemical Kinetics of Photochem-
ical Smog as Analyzed by Computer," AIR-70(8107)-1, The
Aerospace Corp., El Segundo, Calif., December 1969.
Received for review May 30, 1973. Accepted November 19, 1973.
This work was supported by Environmental Protection Agency
Contract 68-02-0580 to Systems Applications, Inc., San Rafael,
Calif, and by National Science Foundation Grant GK-35476 to
the California Institute of Technology, Pasadena, Calif
Volume 8, Number 4, April 1974 339
-------
L. DR. BERNARD WEINSTOCK
RECENT ADVANCES IN SMOG CHEMISTRY
PREDICTION OF FUTURE URBAN CO CONCENTRATIONS
-------
Recent Advances in Smog Chemistry
by
Hiromi Niki and Bernard Weinstock
Abstract
A number of new results have been obtained on the chemistry of
the interactions of hydrocarbons and NO in air to produce oxidant. The
laser induced resonance fluorescence method recently developed in this
laboratory to measure hydroxyl (HO) radical at ambient concentrations in
air has been applied to laboratory smog chamber studies. Good agreement
is obtained between the direct measurements of HO and the concentrations
deduced from the chemical mechanism. The technique has -also been success-
fully applied to the measurement of HO in ambient air.
i
New studies of the chemistry of ozone (O ) and nitrogen trioxidc (NO )
and their role in the removal mechanism of 0_ and NO _ will be reported. The
*•> A.
application of an infrared Fourier Transform Spectrometer to smog studies will
be discussed and preliminary results obtained with our recently developed
instrument will be given.
Talk as given 2/11/75
-------
Direct Measurement of Hydroxyl Radical (HO) Concentrations
Hydroxyl radical (HO) chain reactions have been proposed by us
to answer some unexplained questions of smog chemistry ' and to account
for the balance of carbon monoxide in the atmosphere. ' ' Because
of the importance of these questions, we became interested in the possi-
bility of measuring HO radicals directly at atmospheric concentrations.
This was a very challenging problem because the predicted average con-
centration was of the order of 5 x 10 molecule/cc or 2 ten thousandths
of a part per billion. Early last year, Charles Wang and L. I. Davis
of our laboratory reported their success in developing the technique of
laser-induced fluorescence for this purpose *" .
a. Chemical Calibration of the Laser Measurements
I shall not discuss the laser technique that was developed.
Several talks have been given by Dr. Wang on this subject and a number
of publications have appeared ' . Instead I shall discuss the use of
a smog reactor to make an independent determination of the absolute
concentration of HO by a chemical method at the same time the HO con-
centration is being measured by the laser.
The smog reactor used in these studies was a 50 liter Pyrex
chamber, 1 meter long and 30 cm in diameter, irradiated with standard
GE Black Lights. The HO was produced by the irradiation of mixtures of
HC and NO in a dry helium-oxygen mixture. Helium was
JC
used instead of nitrogen in our dry synthetic air to optimize the
fluorescence yield from HO. Incidentally, we discovered that the
steady-state HO concentration produced in the smog reactor was about
-------
- 2 -
a factor of two greater with He in place of N . This observation is
of course significant, but we have not as yet worked out an explanation
for it. It was also determined that optimum HO results are produced
in the NO-NO conversion phase of the smog chemistry, prior to attain-
ment of the NO maximum. Relative initial concentrations of NO, NO ,
and HC were selected to maintain the system in that region for this
chemical calibration of the laser measurements.
The most reliable results were obtained with HC mixtures.
Representative decay curves for a mixture of cyclohexane, propylene,
1-pentene, and iso-butene are shown in Figure 1. The decay curves are
seen to become pseudo-first order after about 30 minutes irradiation.
In this pseudo-first order region the HO concentration is essentially
constant, which is an important aspect for the reliability of this
2
chemical calibration method . The use of mixtures makes it possible
to determine relative decay rates that can be compared with the known
relative HO rate constants to validate the method. Additional represen-
tative details of the chemistry are shown in Figure 2. To simplify
the plot, the only HC decay curve shown is that for propylene. The
ozone concentration is seen to remain low under these conditions, so that
little correction for the O - HC reactions is needed in deducing the
HO concentration.
Preliminary comparison of the chemical results with the laser
measurements show agreement to about 50%. For the particular HO concen-
tration of 1,3 x 10 molecule/cm shown in Figure 2, the laser result
was 1.6 x 10 . This agreement is quite gratifying, but may be somewhat
-------
- 3 -
fortuitous. Our present estimate of the absolute uncertainties are
greater than this, a factor of 3 for the laser measurements and - 50%
for the chemical measurements. In the above experiments, the measuring
time required to obtain reliable counting statistics was of the order
of one hour. This measuring time can be reduced to 20 minutes, with
the use of a nitrogen laser pumped dye laser and improved collection
optics. This new system has been designed.
b. Outdoor Measurements
Measurements of HO concentrations in the open air outside our
laboratory window were made last summer. Relatively complete diurnal
variations observed for four sunny days in the month of
August are shown in Figure 3. The HO concentrations of 5-6 x 10
molecule/em shown there were the maximum values observed in this study.
On rainy or cloudy days the HO concentration was below the detection
limit of 5 x 10 molecule/cm
The HO concentration values in Figure 3 represent running
averages over 100 or more laser shots. The error bars represent the
»
corresponding statistical uncertainty, which becomes progressively
larger as the HO concentration becomes lower. The absolute uncertainty
is about a factor of three, largely because of the uncertainty in the
fluorescence efficiency of the excited HO.
The second, afternoon HO peak is a little surprising in terms
of our intuitive expectations. A kinetic analysis of the diurnal
variation of the observed HO behavior is in process.
-------
j
HC REACTIVITY (SMOG REACTOR RESULTS
1.0
DILUTION
0.5
u
X
u
0.2
TOTAL [HC]=2.5 ppm
N0x=4.2ppm
CYCLOHEXANE
1
1
i-C4H8
20 40 60 80 100 120
TIME (Minutes)
Figure 1
-------
CONCENTRATION (ppm)
H-
iQ
C
M
rt>
K)
ro
o
m o>
^ o
00
o
o
o
ro
•
o
ro
oo
ro
x:
[OH] (MOLECULE cm"3)
-------
OH Concentration (I07 Molecules/cm3)
o
o
:>
,1
r\>
1 I
•&
1
I
o>
1
1
O>
1
1
o
1
1
o
o
OJ
o
o
5* en
* 8
m
to
H
O
O
CO
o
o
ro
o
o
: I
tl
00 00 00 00
r>> ro rr -K-
Q
-------
.a
o.
O.
O
H
a:
h-
UJ
0
0
o
o
N
O
80
70
60
50
40
30
20
10
0
c
1 r™ i i i i i i i • i i
8-14-74
8-15-74
•j\ r+ 8-21-74 '
"" 1 ** / . .......... P-99-TA
• » ^^ | . .......... o fcfc «*T
X/x*
- /OK^\-.A )\)\f\
// 'w ^^<^^C^r\^^\
- ''"' ^o(/ ^^M^ N. v^_
•^ ^ i * ^^. *
*^* •
X i /
s'' v
-/'
1 1 1 1 1 ' 1 1 1 1 1 1 1
) 10 II 12 13 14 15. 16 17 18 19 20 21
EASTERN STANDARD TIME
-------
- 4 -
Preliminary experiments performed with a tightly focused beam
showed that care must be taken to minimize interference from two-photon
dissociation of water and laser induced dissociation of ambient ozone •
The latter results in HO formation from the reaction of O( D) with water
vapor. These problems were greatly reduced by defocusing the laser
beam and using a reduced energy per laser pulse. The effectiveness
of these changes was established by demonstrating that the fluorescence
yield was then linearly dependent on the.incident power. The correc-
tion for HO produced from 0 dissociation was still significant for
the outside measurements and the HO concentrations shown in Figure 3 have
been corrected for this. The correction factors were based on in situ
measurements with added 0_. With the improved laser, system mentioned
earlier, this problem will be better resolved. No interferences from
other atmospheric constituents were found except for nitrous acid
(HONO). With the present laser system at the exciting intensity used
in the outside measurements it is estimated from experiments done in
the smog reactor that this correction is of the order of 0.5 x 10
HO/cm per ppb HONO. Ambient HONO concentrations are estimated to
•
range from 1-10 ppb.
I
The HO concentrations seen here are consistent with the
average global daytime concentration of 5.6 x 10 molecule/cm deduced
345
from global balance of CO considerations ' ' . It is also consistent
with the HO concentration deduced from atmospheric photochemical
Q
models . Further measurements and detailed analysis -are desirable
before the present results can be taken as validation of these earlier
predictions.
-------
- 5 -
Concurrent measurements of other trace atmospheric constituents
were also made.Figure 4 shows the ozone measurements for the same four
days. They generally remained between 0.03 and 0.05 ppm, although on
one day they rose to above 0.07 ppm. The average CH , CO, NO, and NO
concentrations were 1.55 ppm, 0.5 ppm, 3 ppb, and 20 ppb respectively.
It would obviously be of great interest to apply this HO tech-
nique in field experiments to study HO behavior under a variety of
atmospheric conditions and ozone concentrations.
c. Background HO in Smog Chambers
The chemical behavior observed in smog chamber experiments is
used as a surrogate for atmospheric behavior to estimate vehicular HC
emission control requirements. Basil Dimitriades1 extensive studies
with irradiated automotive exhaust has received particular attention
9
for that purpose . There is a spurious effect observed in smog chamber
experiments that raises a serious question in my mind about the quantitative
conclusions that have been drawn from Dimitriades' fine work. Bufalini et al
of EPA first reported that significant NO-NO conversion rates occur in
^
smog chamber irradiations without the addition of HCs to the system.
They referred to this as a "dirty chamber effect" and were able to
remove it by washing the walls of their glass reactor between runs. The
chamber used by Dimitriades had polished aluminum and glass walls which
could not be cleaned conveniently between runs, and it is probable that
the "dirty chamber effect" was operative in his experiments.
-------
- 6 -
The "dirty chamber effect" has been identified by us to result
from the generation of HO or HO radicals from contaminants during
irradiation. Figure 5 shows a study that was made in our laboratory
with a glass reactor. If only NO is added to the system little
X
NO-NO conversion takes place, indicating that our reactor was rela-
tively clean. When CO was added in 110 and 665 ppm concentration a
substantial conversion resulted. This is explainable ,by the ability
of CO to drive the HO-HO chain reaction that is responsible for the
conversion of NO to NO . Since CO cannot directly produce either HO or HO ,
these radicals must have been produced initially and rather efficiently
from the extremely small concentration of contaminants in the system.
The same is true for the hydrogen experiments. The propylene run is
included for comparison.
Evidence of this effect was also observed in the chemical
calibration of the HO laser measurements I have described. The origin
of the HO radicals is not of importance for the accuracy of that com-
parison. However, we could not account for the HO concentration observed
on the basis of our chemical mechanism calculations. The observed HO
was about an order of magnitude higher than calculated. This large
excess HO that was observed most probably had its origin in the extremely
small amounts of smog products remaining in the system between experi-
ments (the HO initially produced does not have to be replenished
continuously at the same rate because of the long chain lengths involved
in its reactions).
-------
- 7 -
What effect will all this have on the deductions above VES
drawn from smog chamber studies such as Dimitriades'? This should
be carefully worked out. The HC-NO mixtures will undoubtedly appear
X
more reactive and produce 0. at a faster rate than they would in the
absence of this effect.
NO., - HC Reactivity
"—3
A quantitative determination of the removal mechanisms for NO
x
in smog chemistry is of major importance to understand and explain the
long range persistence of ozone. Dinitrogen pentoxide, N2oc' i~s formed
from the reaction of NO and 0 to form NO , and the subsequent reaction
£, 3 -J
of NO with NO . We have previously reported the homogeneous reaction
of N O with water vapor and from the rate constant derived have
t* J
2
shown that this reaction should play a significant role in NO removal .
X
These experiments have been extended to reactions between NO and a
number of olefins. Some experimental results of this study are shown
in Figure 6 for cis-2-butene, Analysis of the data shows that the
NO decays do not result from the direct reaction of NO with cis-2-
butene, but from reaction of NO with the olefin. The NO is in
dynamic equilibrium with NO and NO and the removal of NO by reaction
-------
(ppm NO DECAY VS [CO], [H j AND [CH3 CH •
EXPTL CONDITION
NOyONLY [NO] =0.95 ppm
[N02]=0.4 ppm
k, = 0.33 min.
[CO>IIOppm
[H2> 12,000 ppm
[CO]S665 ppm
1
20 40 60 80
TIME (MIN.)
100 120 140
Figure 5
-------
1.0
.8
.6
.4
1 m
O
CM
10
O
.1
.05
0
5 10 15
TIME CMINUTES]
20
Figure 6
-------
- 8 -
with the olefin is accompanied by a buildup of NO . The relative rate
constants for some NO -olefin reactions obtained are shown in Table 1
and compared with 0 and HO rate constants. These rates are of
sufficient magnitude to warrant inclusion in the mechanisms for smog
chemistry in current use.
O - Olefin Reactions
The chemistry of ozone remains a major deficiency in our know-
ledge of smog. This deficiency takes on greater significance when we
attempt to understand the observations of ozone concentrations in rural
areas in excess of the oxidant AQS of 0.08 ppm. We have been studying
the mechanism and rate constants of the reactions of HCs with ozone.
Some of the rate constants with olefins that were obtained by Japar, Wu,
and Niki in our laboratory were shown in Table 1.
There is a discrepancy between the rate constants we have
measured and those reported by Cvetanovic et al. . For example, for
cis-2 butene we obtain a rate constant of 1.6 x 10 cm /molecule/sec
which, is a factor of 5 greater than Cvetanovic's value of
3 x 10 . Calvert et al's outstanding analysis of the Mechanism of
14
Photochemical Smog Formation used Cvetanovic's ozone rate constants,
while our earlier analysis of the Mechanisms of Smog Reactions used our
ozone rate constant . Consequently, there are significant differences
in interpretation derived from the two analyses.
A probable explanation for the discrepancy between Cvetanovic's
13 12
rate constants and ours lies in the different experimental
methods used. Cvetanovic et al. determined relative rate constants
-------
for olefins based on product analysis and normalized them to an absolute
rate constant for 1-hexene. In addition, their measurements were made
at relatively high reactant concentrations. Our measurements were made
more directly from observations of the rate of ozone decay. In addition,
our experiments were made with sub-ppm 0 concentrations in air so that
they would correspond to real atmospheric conditions. This required
accurate determination of low 0 concentrations, which was made possible by the
use of the 0 -chemiluminescence instrument,
In order to be certain that the rate constants we have obtained
are correct, it is necessary to establish that the observed O decays
are the result of the primary reaction of O with the olefin alone, and
does not include a contribution from the reaction of 0 with reactive
intermediate species formed in the primary reaction. If the latter
occurred to a significant degree, then our rate constants would be too
high. I would like to present some additional experiments we have done
to settle this question.
Figure 7 shows the rate constants derived for the reaction of
O with propylene as a function of the O concentration. It is seen
that the apparent O rate constant increases sharply when the O con-
•J **
centration falls below 50 ppm. This apparent increase in the O rate
constant arises from the onset of 0, reacting with the reactive inter-
mediate species. At higher concentrations of O , the intermediate
species react predominantly with O . Our rate constants were obtained
^
at an 0 concentration of 200,000 ppm so that no correction for this
4U
effect would be necessary.
-------
Table 1
RELATIVE REACTIVITIES OF 0., OH
AND NO TOWARD OLEFINS
OH
c - c
c = c-c
c - c-c-c
c « cc£
Nc - GXC
ft r*
CNC - c'c
^c-c^
** - «c
0.15
1.0
0.92
1.1
20
12
38
110
0.1
1.0
2.4
3.8
4.2
3.6
7
9
0.18
1.0
1.5
21
26
34
1000
7000
* For C = C-C kQ J^OH:kNO = I:106:4xl02
-------
-I _.._ I
•
(O
c o
O
O
C\l
O
lO
E
GL
O 0-
2"
O
O
If)
o
ro
ro
-------
- 10 -
Another way of demonstrating the effect of O reactions with
intermediate species is shown in Figure 8. The apparent rate constant
for the reaction of 0 with propylene is plotted against the ratio of
propylene to O . These experiments were done in helium in the absence
of 0 . It can be seen that as this ratio decreases,
the apparent rate constant increases because
of the reaction of 0 with intermediate species. This does not occur
at the higher ratios because the propylene probably then reacts with
the intermediate species in preference to O . Our rate constant
experiments were performed with a large excess of propylene, the ratio
being in the range 50-100. In addition, in those experiments, the
large concentration of O probably results in the reaction of the
intermediate species predominantly with 0 . This latter effect has
also been demonstrated experimentally in this system.
These experiments then clearly demonstrate that the O decay
in our rate constant experiments was not affected by reaction of
O3 with reactive intermediate species. We have also measured 0 -olefin
rate constants by means of a flow reactor coupled to a quadrupole mass
spectrometer. These experiments were designed to make the possibility
of secondary C>3 reactions even more unlikely. The total reaction time
was reduced to a few seconds. The concentration ratio of propylene
to 03 was increased to 10 . The presence or absence of O did not
affect the rate constants which agreed with our earlier results.
We feel these experiments verify the correctness of our
rate constants and we recommend their use in kinetic mechanism evalua-
tions and in analyses of atmospheric data.
-------
- 11 -
Infrared Fourier Transform Spectroscopy (FTS)
Application of the FTS technique to infrared spectra of smog
reactions was first done by Dr. Philip Hanst of EPA. I would like to
report today some preliminary results that Drs. Maker and Niki of our
laboratory have obtained with our instrument.
Figure 9 shows a computer analysis of complex FTS spectra that
we have obtained for the O -ethylene reaction. The upper trace is a
portion of the overall FTS spectrum observed in this reaction.
The lower three traces are the computer analyzed portions of this
spectrum for formaldehyde, formic acid, and water. One unusual kinetic
feature that we have observed in this system is that the concentration
I
of formaldehyde shown in this Figure builds up very rapidly, but does
not continue to grow and subsequently decays. On the other hand, the
formation of formic acid shows an induction period and then continues
to grow.
Figure 10 shows FTS spectra in another spectral region for
reactions of 0 with ethylene, cis-2 butene, and 1-hexene. The two
-------
Figure 8
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.05 O.I
0.5 I
I
o
-------
Computer Analysis of Complex FTS Spectra
03+
**
HCHO
HCOOH
HoO
i^K^
1900
1800 1700
(cm1)
1600
Figure 9
-------
FTS Spectra of Ozonolysis Products
1200
1100
1000
0* +
1200
1100
o,+c=c-c-c-c-c
1200
1100
(cm"1)
CH3OH
1000
1000
Figure 10
-------
REFERENCES
1. B. Weinstock, E. E. Daby and H. Niki, "Chemical Reactions in Urban
Atmospheres", C. S. Tuesday, ed., American Elsevier Publishigh Co.,
Inc., New York, p. 54 (1971).
2. H. Niki, E. E. Daby and B. Weinstock, Advan. Chem. Ser., 113, 16
(1972).
3. B. Weinstock, Science, 116, 224 (1969).
4. B. Weinstock and H. Niki, Science, 176, 290 (1972).'
5. B. Weinstock and T. Y. Chang, Tellus, 26, 1 (1974).
6. C. C. Wang, Bull. Am. Phys. Soc. , .19, 24 (1974)? C. C. Wang and L. I.
Davis, Jr., Phys. Rev. Lett., 32., 349 "(1974) .
7. C. C. Wang and L. I. Davis, Jr., Appl. Phys. Lett., 3_S, 34 (1974);
J. Chem. Phys. 62, 53 (1975).
8. H. Levy, Adv. Photochem. 9_, 369 (1974) , and references therein.
9. See, for example, B. Dimitriades, "On the Function of Hydrocarbon
and Nitrogen Oxides in Photochemical-Smog Formation", Bureau of Mines
Report 7433 (1970), Bartlesville, Oklahoma.
10. J. J. Bufalini, S. L. Kopczynski, and M. C. Dodge, Environ. Lett.,
_3, 101 (1972) .
11. E. D. Morris and H. Niki, J. Phys. Chem. 79, 1929 (1973).
12. S. M. Japar, C. H. Wu and H. Niki, J. Phys. Chem. 78, 2318 (1974).
13. T. Verbaski and R. J. Cvetanovic, Can. J. Chem., 38, 1053, 1063,
(1960); Y. K. Wei and R. J. Cvetanovic, Can. J. Chem., 43, 913 (1963).
14. K. L. Demerjian, J. A. Kerr and J. G. Calvert, Adv. Env. Sci. and
Tech. £, 1 (1974).
15. D. H. Stedman, E. E. Daby, F. Stuhl, and H. Niki, J. Air Pollut.
Cont. Ass., 22, 260 (1972).
16. H. Niki, A. Warnick and R. R. Lord, SAE Journal, paper 710072 (1971) .
17. P. L. Hanst, E. R. Stephens, W. E. Scott, and R. C. Doerr; "Atmos-
pheric Ozone-Olefin Reactions," The Franklin Institute, Philadelphia,
Pennsylvania (1958).
-------
- 12 -
broad hands observed in the 1100 - 1200 cm region are of particular
interest. Hanst et al at Franklin Institute many years ago using
long path IR spectroscopy had identified the two bands in the 1-hexene-
O. system as the ozonide, which was the first observation of an ozonide
in the vapor phase. The establishment of the ozonide as an intermediate
species in the 0 reactions with lower olefins will play an important
role in unraveling the mechanism of gas phase ozonolysis, which is
currently speculative and controversial.•
The FTS will play a vital role in the improvement of knowledge
of the mechanism and kinetics of smog because it offers the opportunity
not only to observe many important reaction species that have not pre-
viously been observed directly, but also to observe their kinetic
behavior quantitatively.
-------
Prediction of Future Urban
Carbon Monoxide Concentrations
by
Tai Yup Chang and Bernard Weinstock
Abstract
A general rollback formula had been derived that can be used
to calculate the reduction in emissions of inert pollutants, such as CO,
required to achieve the National Ambient Air Quality Standards (AQS).
The predictions of this formula will be compared with those of the
EPA modified rollback formula. Phoenix-Tucson is used as a new example.
It is found that, based on EPA data, Phoenix-Tucson will meet the AQS
by 1985 if an 11 gin/mi vehicle emission standard for CO is adopted. The
EPA has indicated that use of the modified rollback analysis predicts
that Phoenix-Tucson would not meet the AQS by 1985 even if the 3.4 gm/mi
statutory vehicle emission standard for CO went into effect on schedule.
The Phoenix-Tucson analysis will be used to demonstrate the need for a
consistent selection of parameters in the derivation of Vehicle Emission
Standards. The disagreement between the predictions of this model with
those of the EPA are readily explained on this basis. A new preliminary
validation of the predictions of the general rollback formula will be
given, using Los Angeles data for 1965-1972.
Talk as given 2/11/75
-------
I. Introduction
The statutory Vehicle Emission Standard (VES) of 3.4 g/mi for
carbon monoxide (CO) was derived to satisfy the 90% reduction of CO
emissions from 1970 light duty motor vehicles legislated by the Congress
in the Clean Air Amendments of 1970. Subsequently, an ambient Air
Quality Standard (AQS) of 9 ppm, 8 hour average for CO was established
by the Environmental Protection Agency (EPA) to protect public health.
A new methodology will be presented that -can be used to predict the
VES required to meet the AQS of 9 ppm for CO. The predictions of this
method will be compared with the statutory VES of 3.4 g/mi for CO and
with similar predictions made by EPA by a different methodology.
There are a number of uncertainties in the input data used in
these predictions. For example, there are important problems with
_the designation and measurement of air quality and the correct evaluation
of emissions. With regard to the latter, the data provided by the
current Federal Test Procedure (CVS-CH) for vehicle emissions are in-
consistent with the data needed to predict CO air quality with a
correct methodology. These questions will not be gone into in any
detail here. They do not, however, affect the correctness of the
methodology we will present, nor the comparison and analysis of the
differences between our methodology and that currently in use by EPA.
The use of different input data will obviously affect the quantitative
predictions of the model, but we do not believe that this will affect
the general sense of the conclusions drawn from it.
-------
a. Earth Simple Rollback Calculation
Earth used a simple rollback model to estimate the VES for
CO required to achieve the AQS of 9 ppm by 1980. His computation
indicated that a VES of 6.16 g/mi would achieve that goal. An important
*
deficiency of the simple rollback model is its failure to take into
account the spatial distribution of sources. The model inherently
assumes that the highest concentration observed at a particular point
in an urban area is proportional to the total tonnage of emissions
in that area. Thus, if a 50% increase of the total emissions in the
area occurred, the model would predict a 50% increase in the highest
concentration previously observed. This assumption results in the
prediction of a VES more stringent than is required to achieve the
AQS. Another shortcoming of the simple rollback model is that only
a single source category is considered, e.g., in Earth's calculation
only CO emissions from light duty motor vehicles were considered.
The model then inherently assumes that all other CO sources will be
controlled proportionately. In the event that other sources of CO are
-------
- 2 -
controlled to a lesser degree than motor vehicles, the predicted VES
to achieve the AQS would be less stringent than required. This is a
less important deficiency than the previous one as will be shown.
b. EPA Modified Rollback Method
The EPA recognized the deficiencies of the simple rollback
model and derived a modified rollback model to predict whether or not
2
the 9 ppm CO AQS would be met in a number of American cities. The
modified model included non-automotive sources with specific growth
factors and reduction factors. An emission height correction factor
for certain non-automotive source categories was also introduced.
Spatial distribution of sources was not taken into account in the
modified model, although its importance was discussed. Estimates of
the growth of emissions and of the reduction factor for each source
category were used and predictions for the expected future CO air
quality were derived. The estimated growth factors for non-automotive
sources were greater than that anticipated for automotive sources and
the estimated reduction factors were smaller. Consequently, a more
stringent VES for automotive emissions resulted than had been derived by
Earth using the simple rollback method. While it is correct to include non-
proportional rollback of non-automotive sources in the model, the
failure to include spatial distribution of sources still results in
a VES more stringent than required.
EPA concluded that a number of American cities will never meet
the AQS for CO even with implementation of the 3.4 g/mi CO VES on
schedule. This conclusion was recently reaffirmed by Mr. Train in his
-------
- 3 -
press conference following President Ford's State of the Union
Message on January 15, 1975. Mr. Train said that if the statutory
VES for CO were put into effect on schedule that six cities or
regions would still not meet the CO AQS by 1985. In addition, the
five-year deferral of the imposition of more stringent emission
standards for CO recommended by the President would have the effect
of adding a seventh city to that list. Presumably these conclusions
were based on the modified rollback analysis.
c. Other Rollback Calculations
The NAS Committee on the Relationship of Emissions to Ambient
Air Quality considered a number of rollback calculations in which
spatial distribution of sources was also taken into account. In general,
these computations showed the interim California CO VES of 9 g/mi to
be sufficient to meet the 9 ppm CO AQS. A number of these computa-
tions derived VES much higher than 9 g/mi. A weakness of these com-
putations was that they assumed proportional rollback of non-automative
sources. The NAS Committee concluded:
"Available rollback calculations suggest that
the present Federal motor vehicle emissions
standard for CO of 3.4 g/mi is more stringent
than necessary to achieve the ambient CO
standard of 9 ppm by 1990. However, for any
given metropolitan area, this conclusion is
uncertain unless the influence of emissions
from other stationary and transportation
sources and their variations in time and space
are considered."
-------
_ 4 -
I shall discuss today a generalized rollback formulation
that includes both spatial distribution of sources as well as all
categories of CO sources. This formulation has been presented by
my colleague, Dr. Chang, at the Santa Barbara meeting of the American
4
Meteorological Society, September 10, 1974. This generalized model
will be applied in this discussion to predict the VES for CO required
for Phoenix-Tucson to meet the AQS. Phoenix-Tucson is one of the
areas that EPA predicts will never achieve the CO AQS even with im-
plementation of the statutory CO VES on schedule. The same data
used by EPA in their modified rollback model will be used in our
calculation. Our conclusion is that an 11 g/mi VES will be sufficient to
meet the CO AQS there, by 1985, based on these data, contrary to the EPA
conclusion. Furthermore, we shall identify quantitatively the reasons for the
difference in our conclusions. This calculation should also remove
the caveat added to the NAS Committee's conclusion. In addition,
we shall present a preliminary validation of the model we have
derived.
II. Rollback Modeling for Air Pollution Control
a. Generalized Rollback Formula
The relationship between the atmospheric concentration for an
inert pollutant in a given year, C (r), and its emissions sources in the
o
steady-state approximation can be expressed by:
C (r) = A /dr1 F(r, r1) N(r') + B. (1)
o j — — —
A is the emission rate per unit population of emitters and N(r) is
-------
- 5 -
the distribution for the population of emitters. F(r_, r_') is the
source-receptor interaction function that relates the concentration
observed at the receptor to the emissions from a unit source at r_' .
The function F(r_, r') depends upon meteorological conditions such
as wind speed and direction, atmospheric stability, and boundary
conditions (ground topography, limiting mixing height, etc.). B is
the background concentration that is independent of controllable
sources.
The future concentration, Cf(r), is:related to the reduction
factor, R, by:
Cf(r_) = (l-R)A /dr1 F (r_, r_') N(r_') G(r_') + B (2)
where G(r_') is the growth of the population density of emitters. For
convenience, a generalized growth factor G(r_) may be defined as:
G(r_) = Idr' F (r_, r_') N (r') G(r')/ /drj F(r_, r_') N (r_') (3)
This formula in more familiar terminology deduces to:
R = ) - (D-B) (4)
G(P-B)
where P is present air quality and D is desired air quality or the AQS.
In general, P will arise from contributions of a variety of
source categories, i, expressed as:
P = EP.+ B (5)
where:
P. = A. /dr1 F(r, r1) N.(rf). (6)
1 1 J — — — i —
The desired air quality, D, is then:
D = £(1-R.) C5.P. + B (7)
-------
where R. is the reduction factor for source category i and G. is the
growth factor for source category i.
The required reduction factor for any particular source category,
R , such as vehicle emissions, is:
R = [G P - (D-B) + I (1-R.) G.PJ/G P . (8)
j- -L ^. * _J i 1 1 JL JL J-
b. A Specific Formula for Carbon Monoxide
Recent studies conducted to determine the distribution of
CO in cities have shown that the urban CO concentration can be expressed
as:
Co = S + Cb = S + Ca + B (9)
where C0 is the microscale local street term arising from vehicular
JO
sources near the receptor; C, is the urban background concentration;
C is the urban mesoscale term that is related to sources in the
a
entire urban area. We now introduce a ratio:
Y = C£/Ca (10)
which defines the relative importance of the local street term to the
area term.
In the present work, we assume that the present maximum con-
centration, P, is measured in the central business district and that
C^ arises solely from vehicular sources (LDV, MDV, and HDV) that are
saturated with respect to vehicular density at that location, i.e.,
their growth factor is unity-there. The value of C^ also depends on the
slant distance, i.e., the shortest distance from the sampling probe
inlet to the nearest street curb. Now, we may modify the rollback
-------
~ 7 „
formula (8) to evaluate the reduction factor for LDV, R =
(11)
Rl = [P1 ~ (D~B) + l d-R^ *il/pi>
P. = [P-B)Y/(1+Y)]<5.K.H.S./Z6,K.H.S.
i 1111.1111
1
(12)
+ I(P-B)/(1+Y)]G.K.H.S./EK H.S.
i i 1 1 ± , i i
6. = 1 for LDV, MDV, HDV,
= 0 for SA, PP, I.
Here, K. are the fractions of total emissions in the urban area for
each source category i in the base year; H. are correction factors for
emission height and S. are the correction factors for the radial dis-
tribution of emitter populations. Radial distribution correction
factors take account of the different radial distributions of source
categories. The growth factors G. for area sources are evaluated by
use of an area source model and mesoscale diffusion model. The first
term in Eq. (12) is related to C. and the second term to C . In the
Jo 9.
first term, the growth factor is unity.
I regret that time does not permit a more detailed discussion
of our model. I shall be happy to send a preprint of the complete paper
to anyone interested.
III. Application to Phoenix-Tucson
Phoenix-Tucson was one of the regions that EPA predicted would
not meet the CO AQS even if the 3.4 g/mi VES was implemented on schedule.
We have used the same data EPA used in order to compare the two models.
-------
- 8 -
The base year is 1970 and the target year 1985. The present
CO air quality, P, in 1970 is given by EPA to be 42 ppm. The desired
CO air quality, D, in 1985 is the AQS, 9 ppm. The background con-
centration, B, is taken to be 1 ppm. The other parameters used in
the calculation taken from EPA, are given in Table 1.
The results are summarized in the upper part of Table 2. The
sensitivity of the calculated reduction factor, RTr. 'and emission
LDV
rate, E , to the parameter, j, is evident. For meteorological
XjUV
conditions that would apply to P = 42 ppm, y would be much larger than
unity, say 4-6. The required emission standard, based on the EPA data,
is then 11 g/mi and the California interim standard of 9 g/mi would
be more than sufficient to achieve the CO AQS in 1985. In the lower
half of Table 2, similar calculations are made for P = 30 ppm to show
the sensitivity of R__TT and E__TT to P. There is some question of
JjL)V XjlJV
whether the use of the highest or second highest single concentration
observed in any one year is a valid description of P and, if time
permits, I shall discuss this further. In any case, for P = 30 ppm,
£__„ is about 17 g/mi.
.LuJV
We have also calculated the VES for the case of proportional
rollback of non-automotive emissions. The result is 14 g/mi instead
of 11 g/mi or a 30% difference.
The EPA modified rollback model corresponds to the case,
Y = O. Our VES prediction of 5.3 g/mi for that case is greater than
their value of less than 3.4 g/mi. This difference again results from
their failure to take spatial distribution of sources into account.
Because of the saturation effect, their prediction is too low even
-------
Table 1 CO; Phoenix-Tucson. Parameters used by EPA.
LDV MDV HDV PP I SA
0.0 0.015 0.039
0.60 1.0 1.0
5.1 5.2 5.8
0.0 0.4 0.0
K.
l
H,
i
g..^
R,
i
0.863
1.0
2.7
0.050
1.0
2.7
0.47
0.033
1.0
2.7
0.47
Light duty vehicles
Medium duty vehicles
Heavy duty vehicles
Power plants
Industrial sources
Stationary area sources
The fraction of total emissions for source category
LDV
MDV
HDV
PP
I
SA
K.
1 i in 1970
H. : The correction factor for emission height
g. : Annual growth rate (%/year)
R. : Reduction factor
i
-------
Table 2
CO in PHOENIX-TUCSON
P (ppm)
42
42
42
42
Y
0
2
4
6
*LDV
.929
.870
.857
.852
ELDV(g/mi)
5.3
9.7
10.7
11.2
30 0 .851 11.2
30 2 .786 16.1
30 4 .771 17.1
-------
" 9 —
for y = 0. An important point to realize is that the case of y = 0,
which their model implicitly assumes, corresponds to meteorological
conditions where strong winds and good ventilation occur. Under
those conditions, the observed concentrations would be much less than
P = 42 ppm. P would even be much less than 30 ppm and the correspond-
ing VES would be much greater than 11 g/mi, which was derived for the
case P = 30 ppm and y = 0. Alternatively, y = 0 could correspond to
a sampling probe location well removed from local sources.
IV. Preliminary Model Validation
There is much frustration in finding extensive atmospheric
data and the corresponding emissions inventories of sufficient quality
to test our model. The best data we have found are for Los Angeles
8 9
County for the years 1965-1972 ' . We have made a preliminary valida-
tion of our model using those data.
The 99th percentile one hour average CO concentrations were
used as a measure of air quality. The corresponding eight hour average
values were not reported. The highest and second highest values are
too irregular for a useful trend analysis. These 99th percentile
values for six measuring locations in Los Angeles County are plotted
for the years 1965-1972 in Figure 1.
Some smoothing of the data in Figure 1 was done to eliminate
outlying values such as the 1965 Lennox value. The 99th percentile
values for 1965 and 1972 for each of the six stations were taken from
the smoothed curves. The percentage change for each location obtained
-------
- 10 -
from those values is given in Table 3. The 99th percent!le one hour
CO concentration:-, are seen to have decreased by 21 - 331*. in Los
Angolcr, County from 1965 to 1972.
It may be questionable to use.CO data from Los Angeles County
in a trend analysis. A change in measurement method was adopted
there in April 1968. Interference from water vapor was eliminated
at that time with a resulting decrease of the observed CO values.
A careful statistical analysis of these data reported by Tiao et al.
in fact showed a discontinuity in the annual average CO values of
about 5 ppm that occurred in 1968 . This discontinuity is not
apparent in the 99th percentile values shown in Figure 1. A much
smaller correction than 5 ppm would probably apply to them. This is
because the 99th percentile values occur in the winter months when
the water interference would be expected to be minimal.
The emissions inventory for CO in 1965 was 5970 tons/day and
in 1972 was 5489 tons/day. The EPA modified rollback model would
predict an 8% expected reduction in the CO values based on these
tonnages. In contrast, the present model predicts a 25% reduction
in CO when the detailed emissions data for LA county are used. Our predicted
reduction is in excellent agreement with observed reductions. The
comparison with Los Angeles data supports the predictions of future air
quality based on our methodology rather than the predictions of the
EPA modified rollback method.
It would be desirable to have a more extensive test for our
model. We have attempted to use CAMP data for this purpose, but do
-------
Table 3
DECREASE OF THE 99TH PERCENTILES
FROM 1965 TO 1972
AZUSA - 33%
BURBANK - 24%
LENNOX - 24%
LONG BEACH - 28%
L.A. DOWNTOWN - 21%
WEST L.A. - 28%
-------
Figure 1
ANNUAL 99th PERCENTILES (ppm)
ro
o
CM
o
o
CO
Ol
0)
CD
o
->J
I
I
-------
- 11 -
not have the ncct-ssary emission inventories to do a thorough job.
The CAMP data are probably less reliable than the Los Angeles data
for this purpose because of incompleteness, changes made in the
measuring methodology, and a lack of data validation before archiving.
Nevertheless, the EPA reports that except for Denver, the 99th
percentile CO, one hour average, values have decreased by 17-55%
between 1965-1971. The total tonnages of CO emissions nationwide
would have hardly decreased at all based on the published EPA inven-
tories. A fair approximation to the predictions of our model can be
obtained by comparing the average emissions per vehicle for the
12
national average car population for 1965 and 1971 reported by EPA
This ratio is a 17% reduction, which is in fair agreement with the
CAMP data, considering their uncertainty. It is also worth noting
that this is less than the 25% predicted for Los Angeles. This reflects
the implementation of CO emissions control in California two years
before the rest of the nation.
As mentioned in the introduction, there is another important
uncertainty in the predictions made from this model or, for that matter,
in any prediction about future CO concentrations in urban centers.
The CVS/CH Federal test procedure that is used to determine the g/mi
vehicle emissions is based on an average urban driving pattern. This
driving pattern is appropriate for the estimation of the total tonnage
of CO emissions. Our analysis demonstrates that greater weight should
be given to the driving pattern in the urban center, where the highest
CO concentrations are observed. It would, therefore, seem appropriate
-------
- 12 -
for EPA to consider a revision of the driving cycle and the weighing
factors used in the Federal test procedure to give greater weight to
center city driving patterns.
Summary and Conclusions
As a result of our analysis, we conclude that the proposed five-
year VES for CO of 9 g/mi will not adversely affect the attainment
by 1985 of the CO AQS of 9 ppm in Phoenix-Tucson, which EPA has desig-
nated as one of the six areas that will never achieve the CO AQS.
Furthermore, it would appear that there is no need to decrease this
VES in order to achieve the AQS for CO after this five-year extension.
Our conclusion contradicts the current EPA prediction. The trends in
atmospheric CO concentrations observed in Los Angeles County and at
several CAMP stations have been compared with the predictions of
both models. There is good agreement with the predictions of our
model and disagreement with the predictions of the EPA model.
We have also explained the reasons for the disagreement of
the EPA predictions with ours. Primarily the disagreement arises from
their failure to include spatial distribution of sources in their
model. In addition, their model inherently corresponds to meteoro-
logical conditions that would result in complete mixing within an
air basin or to a sampling probe location well removed from local
sources. In contrast, the choice of the annual maximum CO concen-
tration as a definition of present air quality corresponds to atmospheric
stagnation where little mixing occurs and to a sampling probe location
close to the major CO emission source.
-------
- 13 -
The present analysis also suggests that the driving cycle
and the weighting factors used in the CVS/CH Federal test procedure
should be reconsidered to give greater weight to driving patterns in
urban centers.
-------
References
1. D. S. Earth, J. Air Poll. Control Assoc. 20, 519 (1970).
2. "Clean Air and the Automobile", issued by U. S. EPA, June 14, 1973;
"Air Quality and Emission Data and Modeling Results", Technical
Data in Support of Statement to the Public on "Clean Air & the
Automobile", Source Receptor Analysis Branch, MDAD, OAQPS, U.S.EPA,
Research Triangle Park, North Carolina, October, 1973.
3. National Academy of Sciences/National Academy of Engineering, "Air
Quality and Automobile Emission Control, Vol. 3. The Relationship
of Emissions to Ambient Air Quality", August 31, 1974.
4. T. Y. Chang and B. Weinstock, "Rollback Modeling for Urban Air
Pollution Control", Preprint Volume, Symposium on Atmospheric
Diffusion and Air Pollution, Santa Barbara, California, September
9-13, 1974. Published by American Meteorological Society, Boston,
Mass. Also submitted for publication to J. Air Poll. Control Assoc.
5. W. Ott and R. Elinssen, J. Air Poll. Control Assoc., 23, 685 (1973).
6. W. F. Dabberdt, F. L. Ludwig, and W. B. Johnson, Jr., Atmos. Environ.,
_7, 603 (1973).
7. J. R. Kinosian and D. Simeroth, "The Distribution of Carbon Monoxide
and Oxidant Concentrations in Urban Areas", California Air Resources
Board, October, 1973.
8. "Ten-Year Summary of California Air Quality Data, 1963-1972",
California Air Resources Board, January 1974.
9. California Air Resources Board Staff Report 74-21-4A, November 13,1974.
10. G. C. Tiao, G. E. P. Box and W. J. Hamming, "A Statistical Analysis
of the Los Angeles Ambient Carbon Monoxide Data", APCA Paper No.
74-77, 67th APCA Annual Meeting, Denver, Colorado, June 10, 1974.
12. "The National Air Monitoring Program: Air Quality and Emissions
Trends Annual Report", Vol. I, EPA-450/1-73-001-A, U. S. Environ-
mental Protection Agency, Research Triangle Park, N. C. , August
1973.
12. "Compilation of Air Pollutant Emission Factors" Second Ed., AP-42,
U. S. Environmental Protection Agency, Research Triangle Park, N.C.,
April, 1973.
-------
SECTION 5
WEDNESDAY
-------
A. DR. JOHN KINOSIAN
AMBIENT AIR QUALITY TRENDS IN THE
LOS ANGELES BASIN
-------
AMBIENT AIR QUALITY TRENDS
IN THE SOUTH COAST AIR BASIN
Presented at the Scientific Seminar on Automotive Pollutants
Washington, D.C., February 12, 1975 '
by John R. Kinosian
Chief, Division of Technical Services
California Air Resources Board
Because of differences in the procedures of calibrating field oxidant analyzers,
measurements of oxidant by the Air Resources Board (ARB) are generally from
30 to 40 percent higher than by the Los Angeles County Air Pollution Control
District (LACAPCD). The oxidant concentrations measured by the LACAPCD that
are shown on the following slides were adjusted by a factor of 1.35 to make
them equivalent to measurements by the ARB. In a few cases, a factor of 1.4
was used. The ARB and adjusted LACAPCD data are both about 30 percent higher
than the trueoxidant concentrations if measurements by the ultraviolet spectro-
photometric reference method represent true ozone concentrations.
Slide 1 (Average of Daily Max One-Hour Oxidant Concentrations During July,
August, September 1974) shows the average of the high daily one hour concen-
trations during the 92 days of July, August, and September 1974. As shown by
the isopleths, the concentrations range from 10 parts per hundred million (pphm)
in the coastal cities to 30 pphm in the Upland-Fontana area. The stations at
two cities, Mt. Lee and Temple City, in Los Angeles County were those of the
Air Resources Board. The data from these two stations are in very good agree-
ment with adjusted data from neighboring LACAPCD stations, thus supporting
the validity of the adjustment factor.
At three cities, two oxidant analyzers were in operation. These were a KI
and a chemiluminescence instrument at Upland, an ultra-violet photometer and a
chemiluminescence instrument at Fontana, and an ultra-violet photometer and a
KI instrument at Riverside. There is reasonably good agreement of data obtained
by the various instruments.
Slide 2 (Max-Hour Oxidant Concentrations (pphm) 27 June 1974) shows the
geographical distribution of oxidant concentrations during the worst smog day
in 1974. Typically, the highest concentrations are in the Upland area. On
this day three instruments were in operation at Upland, and the max-hour oxidant
concentrations from these instruments ranged from 55 to 63 pphm. The significant
harm level, 60 pphm for one hour may have been exceeded.
Slide 3 (Max-Hour Oxidant Concentrations (pphm), 21 June 1973) is for the
purpose of showing the geographical distribution of ozone on an atypical day.
On June 21, 1973, the highest concentrations were centered around Los Angeles.
Light easterly winds prevailed on this day. Ordinarily the daytime winds
are westerly or southwesterly.
-------
-------
HITK CXIDANT :AYS
PASADENA - 197Q
-ifou OTirANT AS "A.F'N":r r; ~F s: AT VAhur SMHC
* *
Development of, an Ox Mar* Atatecent Strategy
Based en 5mo
-------
OX/DAMT
- AL/GUSr-
34 t-
'> 7966 67 68 69
-------
The next few slides are based on emission inventories and projections in
Los Angeles County for the years 1965 to 1985. Other counties in the South
Coast Air Basin did not have inventories for all of the years shown.
Slide 4 (Reactive Hydrocarbons, Estimated Emissions — Los Angeles County SCAB)
show that hydrocarbon emissions have steadily decreased since 1965. Control of
exhaust hydrocarbon emissions from motor vehicles began with the 1966 model
year car in California. '
Oxides of nitrogen, as shown in Slide 5 (Oxides of Nitrogen Estimated Emissions •
Los Angeles SCAB), increased from 1965 to about 1971-72 and then decreased
slightly.
In California, motor vehicle NOx control began with the 1971 model year car.
In both Slides 4- and 5, the emissions are termed estimates, and there is little
confidence in the absolute values shown. In fact, the numbers have changed
from time-to-time as better data became available. The relative values from
year-to-year are probably meaningful.
Slide 6 (Hydrocarbon to NOx Ratios) shows that the hydrocarbon to NOx ratios
are declining. The importance of this is demonstrated in the next slide.
Slide 7 (Maximum 1-Hour Oxidant As a Function of NOx at Various NMHC Levels)
shows oxidant concentrations as a function of oxides of nitrogen for various
concentrations of non-methane hydrocarbons. The relationships shown in the
slide were developed from smog chamber studies by Basil Dimitriades, and the
irradiation time was six hours.
Superimposed on the chamber data are atmospheric concentrations of 6-9 a.m.
non-methane hydrocarbons and oxides of nitrogen measured in Los Angeles,
and the maximum hourly average concentrations measured in Pasadena, These
measured concentrations were on five days of high oxidant levels in Pasadena
and with airflow trajectories generally from Los Angeles to Pasadena. The
oxidant concentrations determined from the diagram (Y-axis) are in fairly good
agreement with the max-hour oxidant concentration measured at Pasadena.
An envelope area, including the five days with high oxidant levels, 'is shaded,
It is located in an area of maximum oxidant formation. At the left side of
the envelope, assuming no change of hydrocarbon concentrations, increasing
NOx would increase oxidant concentrations. On the right side of the envelope,
increasing oxides of nitrogen would cause a decrease of oxidant concentrations.
Except for the extrapolated area (shown by the dashed lines) decreasing
hydrocarbons always lead to a decrease of oxidants,
The lower envelope shows where the high oxidant days would be if emissions of
hydrocarbons and oxides of nitrogen were reduced from the 1970 levels to the
1985 levels shown in Slides 5 and 6.
Anywhere in the lower envelope, oxidants would be decreased by either decreasing
hydrocarbons or by increasing oxides of nitrogen, i.e. the ratio of NMHC to
NOx should be as low as possible. But the ratio cannot be lowered by increasing
NOx because it is not likely that the air quality standard for N02 will be
achieved in the South Coast Air Basin.
-2-
-------
TEMPERATURE-ADJUSTED
OXIDANT CONCENTRATION ( ppm )
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Other reasons for controlling NOx are that these gases result in the formation
of nitrate aerosols which reduce visibility and may cause health effects, and
because in far downwind (receptor) areas, the oxidant concentrations did not
decrease with increasing NOx.
Slide 8 (Oxides of Nitrogen) shows that NOx concentrations increased from
1966 to 1971 in qualitative agreement with the emission estimates.
Trends of air quality are ordinarily difficult to discern because of the large
variability of concentrations from year-to-year. The trends are more apparent
when the data from a number of stations in an area are averaged, or when three-
year moving mean averages are used. Both smoothing techniques were used in
Slide 8 and in the subsequent slides.
Slide 9 (Oxidant Concentrations) shows the oxidant trends of the three-year
moving means from 1966 through 1973 for the coastal cities - Lennox, Long Beach
and West Los Angeles, and for the major source area cities - Burbank, Reseda
and Los Angeles. The three-year mean is the average of the daily maximum
oxidant concentrations during the months of July, August and September in three
consecutive years. For example, the value of 7 pphm for the coastal cities in
1973 represents the average of about 92 measurements in each of three cities
for each year 1972, 1973 and 1974.
As shown, the oxidant concentrations in the coastal cities have decreased
steadily and substantially since 1966. Concentrations in the major source
area cities decreased substantially from 1966 to 1972, and then increased.
The increase may be attributed to the decrease of NOx emissions which began
in 1971.
The next slide (Slide 10, Oxidant Concentrations) shows that oxidant concentra-
tions increased from 1966 to 1970 in the receptor cities of Azusa, Pasadena,
and Pomona. From 1970 to 1972 there was a precipitous decrease of oxidants.
The decrease cannot be explained by the hydrocarbon control program alone.
Possibly a change of the ratio of HC to NOx in the source area contributed to
the marked decrease of oxidants.
In the far inland cities, Riverside and San Bernardino, oxidant concentrations
have increased since 1966. Today concentrations there are nearly as high as
concentrations adjusted by the factor of 1.35 in the Azusa-Pasadena-Pomona area.
As illustrated earlier, the highest oxidant concentrations today occur in the
Upland-Fontana area. Air monitoring of oxidant was not done continuously in
this area from 1965 to 1974. However, available data show that daily max-hour
concentrations in Upland for 1973 and 1974 (28 and 31 pphm respectively for
the July, August, September months) were nearly twice as high as in 1966 and
1967 (16 and 17 pphm).
Another technique for smoothing trend data is to adjust for weather. Of many
weather parameters, such as wind or inversion height, the temperature aloft
has been found to have the strongest relationship to oxidant concentrations.
The remaining slides concern temperature and oxidant concentrations.
-3-
-------
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MAY-OCTOBER OXIOANT TREND AT
DOWNTOWN LOS ANGELES
3-YEAR MOVING AVERAGE
64
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86
67
68
YEAR
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71
74
-------
Slide 11 (August, Oxidant "Trend" ut Azusa) shows how the year-to-year variability
of oxidmit concentrations obscures the trend. The impact of temperature aloft
is particularly visible in the oxidant change from 1967 to 1968 to 1969, The
0.10 ppliro decrease in 1968 oxidant is associated with a 10°F decrease in
temperature at Bald Mountain.
Slide 12 (Bald Mountain Temperature and Azuaa Oxidant) shows the relationship
between the mean max-temperature at Bald Mountain and the number of days on
which the Azusa oxidant reached 0.10 ppm or more. Bald Mountain is located
in the northwest corner of Los Angeles County at an elevation of 4>517 feet.
Azusa is located in the central inland part of the County at the foot of the
San Gabriel Mountain Range.
Slide 13 (August Oxidant'Trend" at Azusa) shows the three-year moving mean of
the August max-hour oxidant concentrations after adjustment to compensate for
temperature aloft. The marked downward trend of recent years appears to have
ceased, as the 1972-74 data indicate no change from 1971-1973.
The final slide (Slide 14, May-October Oxidant Trend at Downtown Los Angeles)
shows the yearly and three-year moving mean of temperature adjusted daily
max-hour oxidant concentrations at Downtown Los Angeles, for the months of
May through October. The yearly values are shown as solid data points while
the three-year means are shown as a solid line. The adjustment made here is
based on the max-temperature measured at Canoga Park located in the west
central part of the County at an elevation of 790 feet.
The downward trend indicated by the three-year running means from 1966 through
1972 appears to have ended„
-4-
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B. DR. JAMES EDINGER
LOS ANGELES REACTIVE POLLUTANTS PROGRAM
(LARPP)
-------
Contribution of J. G. Edinger
Given at Scientific Seminar on Automotive Pollutants/
Washington, D.C., Feb. 12, 1975
PREFACE
This paper consists of a preliminary analysis of the Los Angeles Reactive
Pollutant Project data prepared for the Coordinating Research Council. The project,
carried out in the summer and fall of 1973, featured a Lagrangian observation
program of air pollution in the South Coast Basin in which the following groups or
agencies participated: the Coordinating Research Council, the Environmental
Protection Agency, the National Oceanic and Atmospheric Administration, the
California State Air Resources Board, the General Research Corporation, the
Systems Innovation Corporation, and Metronics, Inc.
-------
PRELIMINARY ANALYSIS OF LARPP DATA
J. G. Edinger
Section 1
Modification of the tracked air parcel
Introduction
Modelers of urban air pollution face the difficult problem of constructing
three dimensional descriptions from predominantly two dimensional data. Upper
air networks compatible with the surface observational array are too expensive.
The Los Angeles Reactive Pollution Project (LARPP) effects a great economy by
providing a tracer (triad of tetroons) and making vertical soundings by instrumented
helicopter serially in time at the centroid of the tetroons. In this way one avoids
the necessity of monitoring continually in three dimensions the entire South Coast
Basin. Instead a selected mass of polluted air (air parcel) remains under con-
tinuous surveillance for a period of hours as it moves across the area—a real world
analog of the photo-chemist's smog chamber. The elimination of chamber walls
is an important change but it does exact a price. The absense of walls allows
exchanges between the parcel and its enironment. In analyzing the LARPP data
it is necessary to understand the ways in which the tracked air parcel may become
modified by horizontal and vertical exhcnages with its environment and by changes
of shape.
-------
Horizontal exchanges
Horizontal exchanges between the tracked air parcel and its environment
will be small if its characteristics do not differ markedly from the surrounding air.
And this will be so when the parcel is moving over area sources large compared to
its size. Problems will arise in the vicinity of strong point and line sources and
as the parcel crosses the boundaries of area sources.
Vertical exchanges
During the day convective motions originating at the heated ground
propagate the top of the mixed layer upward through the atmosphere by entrain-
ing air at the base of the temperature inversion. In LARPP, by choosing the base
St/
of the inversion as the top of the tracked air parcel, we are dding with a mass
of air which gains mass vertically as convection proceeds. It also may gain
pollutants depending upon the air quality of the air in the inversion layer. These
gains can be determined if the helicopter soundings penetrate the inversion layer.
Fig. 1 gives example of erosion of inversion.
Changes in parcel shape
Air parcels moving across the Los Angeles area may change shape as a
result of three mechanisms: (a) horizontal divergence in the flow, (b) shear of
the wind with height and (c) flow up the heated slopes of the peripheral mountains.
The elaborate configuration of coastline and mountain slopes produces
flow across the area which contains varying amounts of horizontal divergence.
-------
Figure 1» Temperature soundings along computed trajectory across
the Los Angeles Basin, June 1970, showing erosion of
inversion from below by convective action,
(These airplane soundings were all made in the same air
parcel within the limits of the accuracy of the trajec-
tory computed from hourly surface streamline analyses.)
-------
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9 hr heating
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TEMPERATURE in DEGREES CELSIUS
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-------
Fig. 2 illustrates schematically the shallowing and spreading of an air parcel as
it undergoes horizontal divergence. As a result of the spreading the parcel is
exposed to a larger ground surface and therefore a larger rate of pollution input
from ground sources. Otherwise there would be no change in concentration of
pollutants since neither the mass of the parcel nor its volume is changed.
The vertical wind shear/ as illustrated schematically in Fig. 3, enhances
the turbulent exchanges between the air parcel and its environment by increasing
its surface to volume ratio.
When the air parcel encounters the daytime heated slopes of the mountains
it is drawn up the thermal chimney, some of it venting at the ridgeline and some of
it injected into the inversion. Fig. 4 is a schematic explanation of this process.
The importance of this rather severe change of shape is that it introduces pollution
into the inversion where subsequently, if convective mixing reaches that level, it
can be mixed down to the surface. Convective erosion of the bottom of the inversion
then may provide contamination instead of dilution.
A number of these meteorological features which modify the air parcel
as it moves along will be invoked in the analyses which follow to explain selected
portions of the LARPP data.
Section 2
Preliminary Meteorological Analyses
As a basis for apprasing the potential utility of the LARPP data set a number
of analyses are made of selected parts of the data. The bulk of the information used
-------
Figure 2. Schematic of air parcel in horizontally divergent flow
-------
-------
Figure 3. Schematic of air parcel in flow with vertical shear
-------
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-------
Figure li. Schematic of air parcel encountering the heated slopes
of a mountain range*
-------
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is contained in Archive Two, produced by the General Research Corporation. The
remainder (small) was taken from the pilot logs. These analyses are presented below.
History of temperature/ carbon monoxide and ozone distribution for Operation 33
The temperature changes observed in the tracked air parcel from 07:48 to
13:34, PST, Nov. 5, 1975, are presented in the form of a vertical time section on
which isotherms have been drawn (Fig. 5). The temperatures on which this analysis
is based were taken from the helicopter records made while the helicopters ascended
or descended between the levels at which horizontal flight patterns were flown. Fig. 6
shows an example of a temperature profile obtained during these vertical portions of
the flight path and the selected significant data points. The turbulent fluctuations of
the temperature field were eliminated by using only such significant points in the analysis.
The modification of the vertical temperature structure during the interval
07:40 to 13:30 PST is apparent in Fig. 5. The change from nighttime cooling to daytime
heating occurs at the 300 ft msl level at about 08:12 PST. Prior to this time a
nocturnal ground inversion apparently existed in the lowest 300 ft layer of the
atmosphere (top at 400 ft msl). At the beginning of the period (07:40 PST) an upper
inversion was based at 500 ft msl. This began to be eroded from below by convective
action beginning at about 08:30 PST. Thereafter its base propagated upward, finally
rising above the top level of the helicopter flight measurements (approximately 900 ft
msl) at 10:00 PST. Subsequently we have no knowledge of the base of the inversion
(top surface of our air parcel).
The 11:30 PST radiosonde at El Monte indicated that the air column
-------
Figure 5. Vertical time section for temperature, Operation 33,
November 5, 1973.
-------
Temperature in degrees F
HOUR OP DAT PST
12
HOUR OF DAT PST
/3
-------
Figure 6, Temperature profile, Operation 33, Helicopter Smog-2,
November 5, 1973, 08:21 to 08:38 PST.
(Large dots are the chosen significant temperatures
selected for entry on the vertical time section)
-------
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TEMPERATURE in DEGREES FAHRENHEIT
-------
there was convectively mixed up to 2200 ft msl, suggesting that the mixed layer
continued to deepen and more than doubled its depth in the time interval, 10:00
to 11:30 PST. For our tracked air parcel which was traveling from Paramount,
10 mi south of downtown, Los Angeles, twoard the northeast a reasonable first
approximation for its height change would be a linear increase in mixing depth,
perhaps doubling its height by 11:30 PST. One would expect the rate of increase
to be somewhat smaller in this area than in El Monte because here, upwind of the
Puente Hills flow typically develops some horizontal divergence.
r ~ '
With this picture of the parcel's changing depth and cross-sectional area
in mind we examine now the history of the carbon dioxide concentration in the
parcel (Fig. 7). This was constructed from the average concentration for each level
flight pattern and for each vertical flight segment between levels.
The maximum concentration appears near the ground at about 08:30 PST,
approximately the time of the morning traffic peak. Concentrations decrease rapidly
with height, particularly above the base of the inversion. As the mixing depth
increases with time, concentrations in the mixed layer decrease, the result of dilution
from above. In the interval 10:00 to 11:30 PST in which we reasoned above the depth
of the mixed layer might have doubled the average carbon monoxide concentration
changed from about 4 ppm to 3 ppm. In the absence of other effects one might have
expected it to decrease by one half. The fact that the concentration did not decrease
that fast suggests the continued input of carbon monoxide from the ground sources
possibly augmented by the increase in the areal contact of the tracked parcel
-------
Figure ?• Vertical time section for carbon monoxide concentration,
Operation 33, November 5, 1973•
-------
Concentration in ppm
10
I
8
• 9
HOUR OF DAY PST
10
II
/2
HOUR OF DAY PST
/3
-------
with the ground (due to horizontal divergence in the area).
Considering now the ozone concentrations (Fig. 8) one notes that early
in the period (before 08:00 PST) before convective heating gets started concen-
tration increases with height with maximum values found in the upper inversion
layer. With the development of the convectively mixed layer (08:00 - 09:00 PST)
concentrations decrease and become uniform vertically up to the base of the
temperature inversion. Above that concentrations maintain slightly elevated values.
After 09:00 PST there is a regular increase in concentration with time in the mixed
layer in response to photo-chemical reactions and the entrainment of inversion air
with its higher ozone content.
History of temperature, carbon monoxide and ozone distribution for Operation 19
This is a very short history, 11:10 to 13:00 PST. Although the archive
contains measurements from 08:02 to 15:40 PST on this day, only in the two hour
interval from 11:00 to 13:00 PST are regular flight pattern data reported. At the
end of the mission, 14:58 to 15:31 PST, a vertical descent is made, 4000 to 500 ft
msl but it is at El Monte and not near the tracked air parcel. For the two hour
interval the temperature, carbon monoxide and ozone fields are constructed in the
same manner as described in the preceding discussion of Operation 33.
The temperature history (Fig. 9) shows a marked inversion base at about
1000 ft msl which is gradually propagating upward. Below it there exists a con-
vectively mixed layer, superadiabatic lapse rate in the lower part, slightly stable
lapse above.
-------
Figure 8. Vertical time section for ozone, Operation 33» November
5, 1973.
-------
2 -
/o
II
HOUR OF DAT PST
12
HOUR OF DAT PST
/3
-------
Figure 9. Vertical Sections for Operation 19, October 15, 1973.
(a$ Temperature section
(b) Carbon monoxide concentration section
(c) Ozone concentration section
-------
in HUNDREDS OF FEET
o>
r
EC
Q
s.
3
§
(above mean sea level)
-------
/2
&
8
£
e>
I
jnctooid.de
IB 55301
/3
HOUR'OP DAT PST
-------
(c)
10
e
8
S
•—•,
t-t
I
S
S
•s
Ozone concentrations in ppm
I
/2
•
HOUR" OF DAY PST
/3
-------
The carbon monoxide history indicates a regular decrease in concen-
tration with time in the convectively mixed layer and a decrease in concentration
with height in the inversion. Apparently vertical dilution of the tracked parcel
with cleaner inversion air more than offsets the effect of carbon monoxide sources
at the ground at this time of day. Contrasted with the Operation 33 air parcel
at the same time of day this parcel has higher carbon monoxide concentrations
presumably because it has been subject to less dilution from above (shallower mixed
layer).
vl
The ozone history in this two hour interval is uninteresting, only weak
gradients in time and in height. Contrasted with Operation 33 ozone concen-
tractions for this time of day it does have higher values/ again reflecting the parcel's
smaller vertical dimensions.
Vertical profiles of temperature, dewpoint and ozone for Operation 14
Operation 14, as described by Perkins in LARPP OPERATION SUMMARY,
I-
(LARPP Symposium, 12 - 14 November, 1974),was one which encountered quite
lieavy ozone concentrations and although it produced rather few (10) standard air
sampling patterns it did carry out two vertical patterns. One of these, Glendale,
13:01 to 13:25 PST, is evaluated here. See Fig. 10.
The temperature sounding shows an inversion layer of typical vertical
extent, base near 1000 ft msl and top around 2500 ft msl. It's not very strong for
this location (Glendale) and this time of day (13:01 to 13:25 PST), a three degree
-------
Figure 10, Vertical temperature, dewpoint and ozone sounding for
Operation 1U, Glendale, October U, 1973, 13*01 - 13:25
PST
-------
HEIGHT (above mean sea level) in THOUSANDS OF FEET
00^
U!
00
O
O)
-a
3
-------
8
F temperature increase from bottom to top. We have assumed the lapse rate in
the mixed layer to be about adiabatic. Without a surface temperature it could
not be determined.
The ozone profile shows concentrations of about 0.16 ppm in the mixed
layer. In the inversion layer above/ however/ a value of about 0.32 ppm is
reached. Above this (2000 ft msl) the values drop abruptly to less than 0.10 ppm
and remain there to the top of the sounding (4000 ft msl). Relatively high values
of ozone concentrations are often found in the inversion layer (Edinger: 1973).
The inversion layer can become polluted in a number of ways. The two most
probable mechanisms in the Los Angeles area are: (a) horizontal injection from
t
\ c
Oh.,' the daytime thermal chimney on the slopes of the San Gabriel mountains (Fig. 4)
and (b) propagation of the inversion base downward into the polluted mixed layer
during the stabilization that takes place during the late afternoon and nighttime
hours. This is probably the source of the slightly elevated values in the inversion
at the beginning of Operation 33 (Fig. 8). Note that within an hour or two mixing
propagates the inversion base back upward and this air with somewhat higher
concentration of ozone once again becomes part of the mixed layer (fumigation).
If this Glendale air experiences enough further surface heating as it
moves inland its mixed layer will finally reach the layer of high ozone concen-
tration presently imbedded in the inversion at about 1500 ft msl. Then instead of
dilution by entrainment of inversion air through the top of our air parcel there will
be contamination.
-------
The dewpoint profile indicates that the water vapor is fairly uniformly
distributed from the ground up to the bottom of the layer in which the highest
ozone concentration is found/ and then falls off abruptly. This suggests that the
polluted air from 1000 to 1500 ft msl is of marine origin. Being uniformly moist
in the vertical suggests that it probably was captured by the nocturnal descent of
the inversion base. The polluted air of maximum ozone concentration (1700 to
2000 ft msl) being much drier must have encountered a greater dilution with dry
Inversion air which suggests that it arrived via the heated slopes where marked
shallowing and spreading exposed it to much greater vertical exchanges.
Upper wind measurements at El Monte at this time show 7 knots from the
southwest at 1000 ft msl and 6 knots from the west at 2000 ft msl. These winds would
not bring air from the mountain slopes to Glendale at inversion levels but the pre-
vious winds taken at El Monte at sunrise show 2 knots from the east at 1000 ft msl
and 2 knots from the northeast at 2000 ft msl. It is possible, therefore, that slope
injected air may well have been advected out from the slopes of the San Gabriels
past Glendale and then advected back in on the Seabreeze.
The relatively high ozone concentration in this air may be the result of
its longer photochemical history in the inversion, isolated from other pollutants
that could destroy it.
Vertical profiles of temperature, dewpoint and ozone for Operation 15
This data did not appear in the Second Archive but was taken from entries
made in the pilot log. Examination of the temperature, dewpoint and ozone profiles
-------
10
show contaimination of the inversion layer over Upland, Oct. 5, 1973, 16:08
to 16:23 PST (Fig. 11). The fall off of the ozone concentration and dewpoint
with height above the inversion is more gradual. Otherwise the situation is
quite similar to the Glendale case for the previous day (discussed above). Again
it appears that ozone has found its way into the inversion by way of the mountain
slopes. East and northeast winds were observed at inversion heights over San
Bernardino. The possibility also exists that some of the ozone or its precursors
was captured during the night by the downward propagation of the temperature
inversion.
Section 3
Conclusions
There is nothing revealed in the sample analyses of the LARPP data
described above that suggests that the air parcels were not successfully tracked
and monitored for a period of hours—no indication that the integrity of the parcel
was in doubt. The carbon monoxide concentration of the parcel decreased as its
volume increased due to convective deepening during the day and by an amount
approximately proportional to the volume increase.
The observed ozone concentrations increased during the day despite
the fact that the volume of the parcel was increasing at the same time, suggesting
that the photochemical formation rate is great enough to reverse completely the
effects of dilution from above. Also favoring this increase in ozone concentration
during the day was the fact that often the entrainment of inversion air from above
-------
Figure 11, Vertical temperature, dewpoint and ozone sounding for
Operation 15, Upland, Oct 5, 1973, 16:08 - 16:23 PST.
-------
BO F
O
DGWPOINT2O
-------
11
contaminated rather than diluted the parcel/ this because ozone concentrations
were higher in the inversion than in the parcel.
The ozone found in the inversion apparently is the result of nocturnal
propagation of the inversion down into the mixed layer and the daytime injection
of some of the mixed layer into the edge of the inversion along the heated slopes
of the mountains. But these same processes influence the carbon monoxide dis-
tribution and it shows lower concentrations in the inversion than in the mixed layer.
So polluted air which finds its way from the mixed layer to the inversion becomes
further diluted in the process* The fact that ozone does at times occur at higher
concentration in the inversion than in the mixed layer suggests the continuing
photochemical formation of ozone in the inversion and the existence of ozone
destructive processes in the mixed layer.
The analyses attempted did not address the problem of the horizontal
leakage of the tracked parcel. It would require some knowledge of horizontal
^gradients in concentration around the rectangular sides. A field of concentration
can be constructed by drawing i so lines for the rectangular array of points and
x
gradients determined from the spacing of the lines. Several of these were attempted.
The effort was abandoned on the basis that the gradients so obtained were too
strongly influenced by subjective judgments involved in the drawing of the lines.
Neither was the change of shape of the parcel susceptible to analysis.
The few upper wind measurements that were available were not made at the
location of the tracked parcel/ were made only twice a day and didn't have
sufficiently fine resolution in the vertical. Perhaps a detailed study of three
-------
12
dimensional tracks of the tetroons could yield a measure of the wind shear in
the vertical.
-------
Reference
Edinger, J. 0., 1973: Vertical Distribution of Photochemical Smog
in Los Angeles Basin, Env« Sci. and Tech. , 7, 2h7 - 25>2.
-------
C. DR. BRUCE BAILEY
OXIDANT - HC -NOx RELATIONSHIPS FROM
AEROMETIC DATA - L. A. STUDIES
-------
EPA Scientific Seminar
On Automotive Pollutants
February 10-12, 1975
Washington, B.C.
Bruce S. Bailey - Texaco Inc.
Introduction
Thank you Mr. Chairman. Ladies and Gentlemen. I am happy
to be here today and to participate in this conference on the role
of automotive pollutants, particularly nitrogen oxides, in the atmos-
pheric chemistry of oxidants.
The information which I am going to present today is the
result of a study which was undertaken to investigate the factors
which control the achievement of the oxidant standard. Our approach
to this analysis was from the systems point of view. That is, our
objective was to develop broadly applicable relationships which
would indicate the degree to which the oxidant process could be con-
trolled by feasible hydrocarbon and nitrogen oxide strategies within
the real world where monitoring error,, oxidant transport, natural
emissions and anthropogenic emissions were present. It was also an
objective of this analysis that the relationships be developed in
such a manner they would indicate the statistical - probability
aspects of the process.
-------
Slide I
The analysis method which was developed to meet these
objectives is the two step method shown in Slide I. The method
involves: first relating the second highest oxidant concentration
in a year to the-annual oxidant mean and standard deviation, and
then in step 2, relating the annual oxidant mean to the annual means
of the precursor variables - total hydrocarbon, nitric oxide and
nitrogen dioxide.
•The advantages of this two step approach are several —
First, by relating the max-1 oxidant concentration
to the annual oxidant mean and the annual oxidant
standard deviation, a statistically strong relation-
ship can be obtained which indicates the relative
importance of those factors which affect the mean
level of the oxidant process versus those factors
which affect the variability of the process. While
mean oxidant levels are controllable to some degree
by precursor pollutant controls, the variability
component is not and must be taken into account
in setting an achievable standard. The ratio of
the standard deviation to the mean has been found
to be a useful parameter for indicating the degree
to which uncontrollable natural events (principally
meteorology) affect the oxidant process at a given
location.
• Secondly, by relating the annual oxidant mean to
the annual means of the precursor variables, a
-------
Slide I
ANALYSIS METHOD
STEP I max-i TOX *f (m TOX, s TOX)
STEP 2 m TOX* f (/77THC, /^ NO,
max-i TOX « SECOND HIGHEST YEARLY OXIDANT CONG,
m TOX • ANNUAL MEAN YEARLY OXIDANT
J TOX * STANDARD DEVIATION YEARLY OXIDANT
/77THC * ANNUAL MEAN 6-9 AM TOTAL HYDROCARBON
m NO * ANNUAL MEAN 6-9 AM NITRIC OXIDE
/7?N02 * ANNUAL MEAN 24 HR. NITROGEN DIOXIDE
-------
3.
statistically strong relationship can be developed
which indicates the degree to which the oxidant
process can be controlled by the precursor pollu-
tant variables. Our experience with similar cor-
relations using daily maximum or daily mean values
is that these relationships are very weak statistically
and are thus unsatisfactory for analyzing for the effects
of various pollutant control strategies. Upper limit
curves also fall into this category.
While work to date has indicated that the time averaging
periods shown on Slide 1 for the various pollutants produce the
strongest correlations, other time averaging periods can also be
used with only a slight loss in statistical significance.
Since time does not permit more discussion about the
analysis method, I will submit for the record a copy of our paper,
Factors In Achieving the Oxidant Standard, which covers this matter
in greater detail. Also covered in the paper is a description of the
15 city data base which was used in this analysis.
One of the major problems which became apparent early in
this work was the lack of good aerometric data for all geographical
regions and time periods of interest. Only a relatively few urban
and suburban areas of the country possess comprehensive aerometric
data going back in time more than a year or two. Aerometric data
for rural areas is practically .non-existent. Lack of an adequate
aerometric data base has posed real limitations in the development
and validation of the chemico - statistical models which are the
basis of this work.
-------
Slide 2 & 3
The regression equation developed to relate the second
highest oxidant concentration to the annual oxidant mean and
standard deviation is shown on Slide 2. This is a simple linear
relationship which because it does not estimate the entire yearly
oxidant distribution does not require the complexity of the log-
normal equation. The regression statistics show this to be a very
strong relationship. The principal use of this equation is to cal-
culate the probability of achieving the oxidant standard or some
other level of max-1 concentration as a function of the annual
oxidant mean and standard deviation. In the figures to follow,
calculations involving this equation have been made at the 50$ prob-
ability level. While this probability level is satisfactory for
indicating the general relationships which exist between oxidant and
the various pollutants, the calculations do not reveal the full
impact of the "not to be exceeded more then once a year"requirement
6f the standard on the precursor pollutant concentrations required
for compliance. For estimating compliance with the standard, a
much higher probability level is required.
It was stated earlier that the ratio of the annual stand-
ard deviation to the annual mean has been found to be a highly useful
parameter for indicating the effect of uncontrollable natural events
on the oxidant process at a given location. This is illustrated on
Slide 3 where the annual standard deviation(s) and annual mean (m)
values for the cities included in our data base are shown. The data
show that there is a range of s values at each level of the mean and
that the range of s values decreases as the mean is lowered. The
-------
Slide 2
OXIDANT MAX-I REGRESSION
5
~~
max-/TOX
m TOX 1.606
F TOX 6.650
**
R .910
SE .038
-------
Slide 3
FIGURE 2
.07
.06
g.
UJ
o
o
QC
CO
.04
.03
.02
.0!
0X1 DANT ANNUAL MEAN VS STANDARD DEVIATION
15 US CITIES
x DENVER
• WASHINGTON
o CHICAGO
a ST. LOUIS
* CINCINNATI
• PHILADELPHIA
+ AZUSA
'LOS ANGELES 1101
• BAYONNE
„ > CAMDEN
< NEWARK
o LONG BEACH
• LOS ANGELES 2101
» LOS ANGELES CO
* SAN DIEGO
. C
A-*7
.01
.02 .03
ANNUAL MEAN
.04
.05
-------
relative oxidant variability of a station is indicated by the s/ra
ratio. For this data base, the s/m ratio varies from about .55 to
1.33. Stations with high s/m ratios reflect the existence of con-
ditions (primarily meteorological) which produce a high level of
oxidant variability while stations with low s/m ratios reflect the
opposite situation. It should be noted that s/m ratios of the
yearly data for each of the locations tend to lie about a line of
constant s/m ratio. The use of the historical s/m ratio leads to
the best estimate of the mean oxidant concentration needed for com-
pliance with the oxidant standard at a given location. Line CD on
the slide shows the mean oxidant and standard deviation values needed
for compliance at a 50$ probability level as computed from the equa-
tion 5, Slide 2.
-------
6.
Slide
The relationship between the annual oxidant mean and the
annual means of the precursor variables is shown on Slide 4. In
the presentation of our work last October to the Southeastern
Regional ACS meeting, the equation shown as number 9 represented
the best equation developed to that time. Since that time^ further
work has shown that the reciprocal of the NO concentration is as
useful as the THC/NO ratio used in the original equation and that
the introduction of the N02/N0 ratio significantly improves the
relationship. The effect of including these parameters is shown
in Equation 25 and 26, respectively.
Equation 25 points up the inverse relationship which
exists between the annual oxidant mean and the annual mean NO con-
centration. As will be shown on later slides, this indicates that
control of nitric oxide to low levels is counterproductive to the
control of oxidant at these urban sites. This general observation
is modified somewhat by the implications of equation 26 where the'- .
effect of N02/NO ratio is taken into account.
The regression statistics shown for all of these equations
indicate that the relationships between the annual oxidant mean and the
annual means of the precursor pollutants are strong. This is a
necessary condition for any relationship which is to be used for
analyzing pollutant precursor effects on oxidant control.
-------
Slide
OXIDANT-PRECURSOR REGRESSIONS
/77THC
777 THC/NO
m I/NO
777 NOg/NO
9
TOX
.0020
.0047
.0003
25
JwTOX
-.0082
.0078
.0008
26
-.0066
.0072
.0004
.0114
R
SE
.792
.005
.792
.005
.815
.005
-------
7.
Slide 5
The reason for the inclusion of the N02/N0 ratio term in
Equation 26 is shown on Slide 5. Here is shown the N02/N0 ratio as
a function of NO concentration. The data show that the relationship
is non-linear with high NO /NO ratios being observed at low NO con-
centrations for some of the data. This is interpreted to be the
result of oxidant transport wherein the effect of advected oxidant
is to increase the N02 concentration while decreasing NO concentra-
tion. It is interesting to note that the station which most clearly
shows this effect in our data base is Azusa. Because of the clear
indication that the N02/N0 relationship is non-linear, the N02/N0
ratio together with the NO concentration term were included in the
final equation.
The next several slides show the oxidant - hydrocarbon -
nitric oxide relationships projected by the two-step method. For
these projections, the equation shown as number 5 on Slide 2 and the
equation shown as number 26 on Slide 4 were used. All calculations
are made at the 50$ probability level.
-------
Slide 5
ANNUAL MEAN ^§~ VERSUS ANNUAL MEAN (NO)
(NO)
I,
2.0
1.0
IE
x DENVER
• WASHINGTON
o CHICAGO
D ST. LOUIS
A CINCINNATI
• PHILADELPHIA
+ AZUSA
v LOS ANGELES 1101
> CAMDEN
< NEWARK
.' V
.05
.10
rn(NO)
.20
-------
8.
Slide 6
The relationship between the second highest oxidant concen-
tration and the annual mean precursor pollutant concentrations is
shown on Slide 6 for sites where oxidant transport and oxidant vari-
ability are not a problem. Such sites are characterized by low
values of the N02/N0 ratio and low values of the s/m ratio, respec-
tively, and are classified as source sites.
The cross-hatched area on the slide shows the upper limit
of the methane background. Depending upon the concentration of
natural hydrocarbons present at a site, the lower limit of feasible
hydrocarbon control strategies must obviously be above this limit.
The information shown on Slide 6 incidates that reducing
NO concentrations under conditions of low oxidant transport and vari-
ability reduces the effectiveness of hydrocarbon reduction for the
control of oxidant. Based on these data, it appears that the optimum
pollutant control strategy involves reducing NO concentration only to
the level necessary to meet the N02 standard. Reducing NO concentra-
tion below this level increases the max-1 oxidant levels which are
achievable with a given level of hydrocarbon control. It should
also be noted that the present max-1 oxidant standard of .08 is
not achievable with any'feasible strategy because the total hydro-
carbon concentrations required for achievement lie in the range of
the methane background.
-------
Slide 6
TOX-THC-NOX RELATIONSHIP
SOURCE SITES 5//77 = 0.9
max-1 TOX
.333
.385
CM -__
o .455
.555
.714
.16
.14-
.12
.10
.08
.06
.08 .10
.15
,20
0
1
2.
m THC
.25
J
4
-------
Slide 7
The effect of moving to a receptor site where N02/N0 ratios
are high and s/m ratios are low is shown in Slide 7. Under these
conditions, NO concentration exerts a larger effect on oxidant con-
centration than in the previous case where N0?/N0 ratios are small.
This is consistent with the interpretation that decreasing the NO
shield at a location subject to high levels of oxidant advection
will increase oxidant concentrations. It should also be noted that
the effect on oxidant concentration of changing NO concentrations is
larger for this case than for the previous case where NOp/NO ratios
were low.
-------
Slide 7
TOX-THC-NOx RELATIONSHIP
RECEPTOR SITES S//77 = 0.9
.71
1.0
1.67
.10
.08
o
z
IS
.06
.04
.02
0
0
max-1 TOX
,15 .20
_2
/77THC
.25
.30
-------
10,
Slide 8
The effect of moving to source sites where meteorological
and other factors produce high s/m ratios and the N02/N0 ratio is
low is shown in Slide 8. As compared to Slide 6 where the s/m
ratio and NCU/NO ratio are both low, the slide shows that the
effect of increasing s/m ratio is to reduce the mean hydrocarbon
concentrations which are required to achieve the oxidant standard.
While increasing the level of hydrocarbon control necessary to achieve
the standard, increasing the s/m ratio does not change the relative
improtance of hydrocarbon versus nitric oxide control. In this case,
as in the previous cases, the optimum NO control strategy is to con-
trol only to those levels required to meet the N02 standard.
-------
290*
-------
11.
Slide 9
To round out the picture, Slide 9 shows the situation
projected for a receptor site which is subject to conditions which
produce high s/m ratios. As compared to Slide 7 where the s/m
ratios are low, these data would indicate that the effect of increas-
ing s/m ratio is to reduce the mean hydrocarbon levels which are
required to achieve the standard. These models predict' similar s/m
effects at both receptor and source sites.
-------
Slide 9
TOX-THC-NOX RELATIONSHIP
RECEPTOR SITES s/ms\A
.71
o
z
1.67
.10
.08
.06
.04
.02
2
/77THC
-------
12.
Summary
In summarizing, the following points should be made:
•Presently we believe that the situation projected by
these models for source sites probably represents the best esti-
mate of what the limits on oxidant control might ultimately be by
feasible hydrocarbon and nitrogen oxide emission control strategies.
As oxidant levels are reduced in the future by the fruition of pres-
ent control strategies, receptor sites will tend to become source
sites. The analysis of the behavior of source sites thus becomes
of special interest as indicating what the ultimate limits of oxi-
dant control might be.
• Based on this analysis, it would appear that the concur-
rent reduction of nitrogen oxides and hydrocarbon emissions to as
low a level as possible is counterproductive to-the control of
oxidant. Ambient NO concentrations should not be reduced below
those required to meet the NC>2 standard. In this connection, these
models would indicate that the permissable level of NO concentration
to achieve NO^ compliance is a function of local photochemical activ-
ity. Since most locations are now in compliance with the NOg stand-
ard and photochemical activity is trending down, further reductions
in ambient NO concentrations would not appear to be necessary. The
exception to this general statement is, of course, the California
South Coast Air Basin, where all indicators point to a very high
level of photochemical activity. The analysis also confirms the
importance of controlling hydrocarbon emissions to control oxidant,
but indicates that the present oxidant standard is probably unachiev-
able on a broad and continuing basis.
-------
13
• This work has also shown that the 2-step analysis method
is an accurate method for predicting max-1 oxidant concentrations
from precursor pollutant concentration data. We believe that it
provides the basis for the development of an improved control
methodology and should be considered for this use. It is flexible
and can be developed on a region-by-region basis if sufficient
aerometric data are available. Also because the method is based
on a robust use of aerometric data, it can be used to quantify the
probability-confidence level trade-offs involved in the standard
setting process.
Thank you
-------
D. DR. JOHN HEUSS
SMOG CHAMBER SIMULATION OF
LOS ANGELES ATMOSPHERE
-------
GM
EV # 12
RESEARCH PUBLICATION •GMR-1802
SMOG CHAMBER SIMULATION OF
THE LOS ANGELES ATMOSPHERE
Jon M. Heuss
Environmental Science Department
February 10, 1975
R ESEARC H LABORATORIES
GENERAL MOTORS CORPORATION • Warren, Michigan
MAY BE DISTRIBUTED OUTSIDE GENERAL MOTORS ... Not to be Reproduced Without Permission
-------
Smog Chamber Simulation of the Los Angeles Atmosphere
by
Jon M. Heuss
Environmental Science Department
General Motors Research Laboratories
Warren, Michigan
Presented at
Environmental Protection Agency
Scientific Seminar on Automotive Pollutants
February 10-12, 1975
Washington, D. C.
-------
ABSTRACT
The finding that low-molecular-weight paraffins can react under certain
conditions to produce elevated ozone concentrations coupled with the
finding of an abundance of paraffins, presumably from natural gas leakage
and petroleum seepage, in Los Angeles has raised the question of what
level of ozone can ultimately be reached in this urban atmosphere.
Therefore, smog chamber experiments which include the contribution of natural
paraffins and simulate both present Los Angeles concentrations and
expected future concentrations have been conducted.
A 10-hydrocarbon mixture was made up, based on detailed hydrocarbon
analyses of Los Angeles air. This mixture was separated into two frac-
tions -- a fraction representing controllable hydrocarbons and a fraction
consisting of light paraffins, presumably from natural gas leakage.
This mixture was irradiated at conditions representative of ozone-alert
days in Los Angeles. Then the effects of 50-, 80-, 90-, and 100-percent
control of the controllable hydrocarbon fraction were investigated,
together with varying degrees of nitrogen oxide control.
The results confirm that 03 and N02 formation are a function of both
hydrocarbon and NO concentrations and that NO inhibits ozone formation
/\
at realistic atmospheric conditions. With even 100 percent control of
the controllable hydrocarbons in Los Angeles, these experiments indicate
ozone concentrations up to 1/10 of present maximum concentrations.
Hydrocarbon control was much more efficient in reducing both peak ozone
concentrations and ozone dosages than nitrogen oxides control. Hydrocarbon
control should also reduce peak nitrogen dioxide concentrations, but
will probably not affect average nitrogen dioxide concentrations.
The results are discussed in terms of the degree of hydrocarbon and
nitrogen oxides emissions control necessary to meet ozone and nitrogen
dioxide air quality standards in the Los Angeles Basin.
-------
INTRODUCTION
The determination of the degree of emission control needed to meet ozone
and nitrogen dioxide air quality standards in the Los Angeles Basin has
been the subject of considerable study. A number of approaches have
been used. They all have both advantages and limitations. Roll-back
models, while simple, ignore the complex chemistry which is known to
occur. Approaches which rely on the analysis of ambient data are also
hampered. They try to use differences in monitoring data which are due
to differences in meteorology to predict the effect of changes in emissions.
Smog chamber simulations overcome this problem. Either the meteorological
variables can be held constant and the effect of changes in emissions
can be measured directly or the emissions can be held constant and the
effects of meteorological variables can be studied. But, smog chambers
have limitations, too. An inability to reproduce the dynamic nature of
the atmosphere and the presence of poorly understood wall effects are
perhaps the most important. Nevertheless, most of our knowledge of
photochemical smog has come from laboratory studies, and results of
laboratory studies are the basis for the regulations on hydrocarbon
emissions.
Dimitriades1 smog chamber study has been used to predict the degree of
234
hydrocarbon and nitrogen oxides control needed in Los Angeles. '
However, the design of Dimitriades1 study did not take into account the
impact of light paraffins in the Los Angeles Basin. In 1962, Neligan
first reported a relative excess of low-molecular-weight paraffins in
the Los Angeles atmosphere as compared to the composition of auto exhaust.
This has since been confirmed by others, and the light paraffins have
been attributed to a combination of natural gas leakage, petroleum
r -l Q
seepage, and gasoline evaporation losses. " ' Furthermore, Altshuller
g
et al. found that low-molecular-weight paraffins can react at high
hydrocarbon to nitrogen oxides ratios to produce ozone. This has also
been confirmed by others. ' These findings indicate that the contribu-
tion of light paraffins cannot be neglected, and raise the question of
what ultimate level of ozone can be reached in Los Angeles with even
complete control of present known hydrocarbon sources.
-------
Two series of experiments have been conducted in the GM Smog Chamber to
investigate the impact of paraffins on Los Angeles smog. First, experi-
ments with paraffin/nitrogen oxides mixtures were conducted which have
confirmed the reactivity of light paraffins at high hydrocarbon to
nitrogen oxides ratios; second, a series of experiments which include
the contribution of natural gas paraffins was conducted simulating both
present Los Angeles concentrations and expected future concentrations.
The objective was to determine the degree of hydrocarbon and nitrogen
oxides emissions control necessary to meet air quality standards for
ozone and nitrogen dioxide in Los Angeles.
EXPERIMENTAL
The experiments were conducted in the GM Smog Chamber, which is an
3
8.4 m stainless steel chamber. Spaced symetrically inside the chamber
are 19 Pyrex lamp tubes, each containing 10 blue fluorescent lamps, two
black lamps, and one filtered sunlamp. The facility has been described
12
in detail previously.
Before each run, the chamber air was purified. It was recirculated thru
a furnace containing a rhodium/alumina catalyst at 510°C for 16 hours at
a flow rate of 57 £pm. Irradiation of the dilution air with or without
added NO produced less than 0.01 ppm ozone.
A
Research-grade olefins and paraffins and research- or pure-grade aromatic
hydrocarbons were used. For the multicomponent hydrocarbon experiments,
a gaseous mixture representing natural gas constituents, and gaseous and
liquid mixtures representing evaporative plus exhaust emissions were
made up. Known volumes of the appropriate mixtures or pure gases were
measured out and added to the preheated chamber. The mixtures were
irradiated for six hours at 35°C. The light intensity, as measured as
the first-order rate constant for the photolysis of nitrogen dioxide in
nitrogen was 0.4 min" . The dilution air had a dew point of 15°C. Ozone
-------
was measured with a chemiluminescent ozone analyzer, calibrated with the
Federal Reference Method. Nitrogen dioxide was measured with an automated
analyzer, using the Saltzman method.
The sample volume withdrawn for analysis was replaced by catalytically
purified air that diluted the chamber contents by about 20 percent at
the end of a typical run.
Ozone Production from Paraffin/NO.. Mixtures
4 " "~"" '"*""" J" ' ^ * «—•—-! * ""'"•— - - - • --» -->—"—• ••ftT T •—• r;-i -.
A series of screening experiments was conducted to measure the ozone
production from various paraffins as a function of hydrocarbon to nitrogen
oxides ratio. The paraffins studied were: methane, ethane, propane,
n-butane, isopentane, and n-hexane. In each case, 3 ppm of the paraffin
was irradiated with varying oxides of nitrogen concentrations between
0.02 and 1.5 ppm. The maximum 1-hour ozone concentrations are shown in
Figure 1 as a function of the initial NO concentration. Irradiation of
J\
methane/NO mixtures did not produce significant ozone. However, all
A
the other paraffins studied did. Ethane, propane, and n-butane each
produced progressively more ozone over a wider range of initial NO
/\
concentrations. The C, to Cg paraffins produced between 0.2 and 0.3 ppm
ozone over even a wider range of initial NO concentrations than ethane
9
and propane. These results confirm Altshuller et al.'s finding that
the HC/NO ratio at which ozone begins to form and at which ozone produc-
/\
tion maximizes decreases as the reactivity of the hydrocarbon increases.
The maximum ozone yields in this study are considerably lower than those
g
reported for similar mixtures by Altshuller et al. although the HC/NO
A
ratio at which ozone begins to form is somewhat lower. There are three
differences between the studies, which would have a bearing on the
maximum ozone production. The first is a spectral distribution effect.
Jaffe et al. have found a large effect of spectral distribution (at
constant Kd) in the propylene/NOx system. Irradiation in the wavelength
band below 360 nm increased reaction rates significantly, presumably due
-------
to other photolytic processes which lead to free radical production.
The irradiation in Altshuller's chamber overemphasizes the wavelength
band from 335 to 365 mn relative to either the sunlight distribution or
the GM Chamber distribution. ' ' This should lead to greater reactivity
in the Altshuller study. Secondly, the dilution air in Altshuller's
chamber contained background hydrocarbons (sufficient to produce 0.06
ppm oxidant when irradiated with 0.2 ppm NO ) which would contribute to
^\
greater ozone production. Finally, Altshuller's results were corrected
for dilution, whereas the results in Figure 1 were not. All three
factors would be expected to increase the ozone concentrations in Altshuller's
experiments. Despite the differences in absolute levels of ozone produced,
both studies indicate that low-molecular-weight paraffins have significant
reactivity at high ratios of hydrocarbons to nitrogen oxides.
Experimental Design of Los Angeles Simulation
The concept of this series of experiments was to irradiate a baseline
mixture representative of pollutant levels on the worst smog days in Los
Angeles and then investigate the effects of varying degrees of hydrocarbon
and nitrogen oxides emission control. The composition of the baseline
mixture (shown in Table I) was chosen based on the Los Angeles Air
Pollution Control District's monitoring data for early morning concentra-
tion on oxidant 'alert' days from 1965 thru 1969. Carbon monoxide was
included because of recent evidence of its role in photochemical smog. '
The composition of the hydrocarbon fraction was chosen by comparing
measurements of the detailed hydrocarbon composition in Los Angeles8'17'18
in on
with measurements of the detailed composition of automotive exhaust '
21 22 23
and evaporative emissions. ' Stephens and Burleson concluded that
the hydrocarbon composition of ambient air resembles a mixture of auto
exhaust plus natural gas plus evaporative emissions. In addition,
Q
Altshuller et al. found that ten hydrocarbons account for about 80
percent of the nonmethane hydrocarbon loading in Los Angeles. Thus, it
appeared that a 10-hydrocarbon-mixture separated into two fractions --
one representing exhaust plus evaporative emissions and the other
natural gas -- would adequately simulate the Los Angeles hydrocarbon mix.
-------
The composition of the mixture chosen is shown in Table II. The exhaust
plus evaporative fraction represents the controllable hydrocarbons in
Los Angeles. The effects of 50-, 80-, 90-, and 100-percent reductions
in this controllable hydrocarbon fraction were investigated, together
with varying degrees of nitrogen oxide emission control. The baseline
carbon monoxide concentration was reduced along with controllable
hydrocarbon fractions since hydrocarbons and carbon monoxide are being
controlled to approximately the same degree.
RESULTS
Maximum Ozone Concentrations
The reaction profile of the baseline experiment is shown in Figure 2.
The nitrogen dioxide peaked in 90 minutes and the maximum ozone concentra-
tion of 0.40 ppm was produced in about four hours. The maximum 1-hour
ozone concentrations formed in all the experiments are shown in Figure
3. As the controllable hydrocarbons are reduced, the maximum ozone
concentrations are markedly reduced. On the other hand, reduction in
NO at a constant hydrocarbon level resulted in an increase in maximum
A
ozone concentrations before any reduction is achieved. These results
show that the maximum ozone concentration is not very sensitive to NO
/\
over a wide range of NO concentration. This differs markedly from
1
Dimitriades1 results which showed a much more pronounced effect of NO .
/\
However, Dimitriades used auto exhaust as the hydrocarbon source and did
not take into account the presence of natural gas paraffins. The difference
between this study and that of Dimitriades is attributed to the presence
of the light paraffin background moderating the effect of nitrogen
oxides.
These results confirm that with realistic atmospheric mixtures, hydrocarbon
control is much more efficient than NO control in reducing ozone. The
A
set of experiments with 100 percent reduction of the controllable hydro-
carbons confirms that a significant ozone concentration (up to 1/10 of
-------
the baseline result) can be produced from a mixture of methane, ethane,
propane, and butane, alone. Since the location of the ozone maximum in
the curves shifts to lower NO concentrations as hydrocarbons are reduced,
A
these experiments also predict that reducing ozone by nitrogen oxide
control will be difficult, if not impossible.
Ozone Dosage
The ozone dosages for these experiments are shown in Figure 4. The
pattern for ozone dosages is similar to that for maximum ozone concentrat-
ions, indicating that the conclusions concerning maximum ozone concentra-
tions should hold for ozone dosages as well.
Maximum NO,, Concentrations
The maximum 1-hour N02 concentrations are shown in Figure 5. Peak N02
concentrations are affected by both HC and NO control. Hydrocarbon
X
reduction, by itself, significantly reduces peak N02 concentrations. As
expected, nitrogen oxides reduction further reduces peak N02 concentrations,
NO,, Dosage
The N02 dosage results are shown in Figure 6. In contrast to results
for peak N02 concentrations, N02 dosage was not affected by hydrocarbon
reduction. In this set of experiments, the NO- dosage was essentially
proportional to the initial NOY concentration. Since these mixtures
A
simulated both present-day concentrations and a wide range of possible
future concentrations, this result provides support for the assumption
that reductions in nitrogen oxides emission will result in approximately
proportional reductions in average N02 concentrations.
Meeting Air Quality Standards in Los Angeles
The application of this or any other laboratory study to the atmosphere
must be considered with extreme caution. However, the suitability of
-------
smog chamber experiments in simulating the atmosphere has been studied
24 25
by Altshuller et al. and Kopczynski et al. They collected samples
of downtown Los Angeles air in large plastic bags and exposed them to
natural sunlight. They found that the rates of hydrocarbon reaction
under these conditions were similar to those reported in laboratory
studies. They also found that the ozone concentrations produced in
their bag irradiations were comparable to those measured at a number of
nearby monitoring stations. They concluded that their results provided
a validation of the smog chamber technique for studying atmospheric
chemistry. It is heartening that the maximum ozone produced and the
time scale of the reaction for the baseline mixture of this study is
comparable to that observed in the atmosphere for similar mixtures.
While it is unlikely that the absolute concentrations produced in the
smog chamber would be directly applicable to the atmosphere, the use of
these results in a relative sense appears justified. That is, if one
wanted to reduce ozone concentrations in Los Angeles by 80 percent, the
combination of hydrocarbon and nitrogen oxides control which reduced the
baseline ozone concentration by 80 percent might well apply in the
atmosphere.
Some examples follow of how these results might be used to estimate the
hydrocarbon and NO control necessary to meet various air quality standards
/\
in Los Angeles. In order to apply this approach, the percent reductions
in Oo and NO- necessary to meet various air quality standards must be
known. Since the baseline mixture is representative of late 1960's
atmospheric concentrations, the comparable maximum concentrations of 0^
and NOp during the late 1960's are needed. These are shown in Table III,
along with the Federal and California air quality standards and the
?fi
percent reductions required. These percent reductions are subject to
a certain degree of uncertainty, since the measurement of both N07 and
27 28
03 have been questioned. The EPA has not yet specified a new
reference method for N02» and the Federal Reference Method for ozone has
been called into question. It is possible that the existing ambient
measurements may have to be corrected and/or that the air quality standards
for 0- and 1^ may be changed.
-------
In any case, the 03 and N02 reductions specified in Table III were
applied to the smog chamber simulation with the results shown in Figures
7 and 8. The hydrocarbon reduction required to meet the Federal oxidant
standard, and the NOX reduction required to meet the Federal N02 standard
are shown in Figure 7. This figure emphasizes the effect of nitric
oxide inhibition on meeting the ozone standard. If NO were not controlled,
only 80 percent hydrocarbon control would be necessary to meet the
Federal ozone standard. If 75 percent NO control were required, over 95
percent HC control would be necessary. Any combination of HC and NO
A
control which ends up in the cross-hatched area would simultaneously
meet both the Federal 03 and N02 standards. The minimum emission reductions
necessary are then 90 percent for HC and 45 percent for NO . It is both
/\
interesting and unexpected that this result is similar to that obtained
from simple roll-back calculations.
The emission reductions required to meet the California air quality
standards are shown in Figure 8, along with the emission reduction
necessary to meet a 0.5 ppm/1-hour N02 standard. The emission reduction
necessary to meet the California air quality standards are 87 percent
for HC and 45 percent for NO. On the other hand, if there were a
A
short-term N02 standard of 0.5 ppm, emission reduction of 75 percent for
HC and none for NOX would be sufficient. Obviously, the degree of
emission control required is highly dependent on the choice of air
quality standards for both 03 and N02>
CONCLUSIONS
These experiments have shown that the contributions of natural gas paraf-
fins is important in photochemical smog and should be considered in any
control strategy decisions. In the future as other hydrocarbons are
controlled in Los Angeles, the importance of the contribution of natural
gas leakage and petroleum seepage will grow. These results confirm that
ozone formation is a function of both hydrocarbon and nitrogen oxides
concentrations and that nitric oxide inhibits ozone formation under
-------
realistic atmospheric conditions. Hydrocarbon control is much more
efficient than NOV control in reducing 0,. In fact, this study indicates
X O
that reducing CL by NO control will be difficult, if not Impossible.
O X
Hydrocarbon control, by itself, will reduce peak NOp concentrations but
will probably not affect average NC concentrations.
-------
Table I. Composition of Baseline Mixture
Nitric Oxide 0.55 ppm
Carbon Monoxide 15.0 ppm
Hydrocarbons 8.1 ppmC
10
-------
Table II. Hydrocarbon Composition of Baseline Mixture
Exhaust Plus
Evapprative Emi ssions
0.025 ppm ethane
0.025 ppm propane
0.145 ppm n-butane
0.125 ppm isopentane
0.17 ppm ethylene
0.07 ppm propylene
0.09 ppm benzene
0.165 ppm toluene
0.09 ppm m-xylene
Natural Gas
2.8 ppm methane
0.25 ppm ethane
0.11 ppm propane
0.04 ppm n-butane
11
-------
Table III. Reductions in Ozone and Nitrogen Dioxide Required
in Los Angeles Basin to Meet Various Air Quality Standards
Air Quality Standard
Agency Concentration
Maximum Observed Reduction
Averaging Concentrations Required
Time (1965-1969 Average) (percent)
Ozone
Federal
California
0.08
0.10
1 hour
1 hour
0.62
0.62
87
84
N i t r o g e n D i o x i
Federal
California
0.05 Annual Average 0.09
0.25 1 hour 0.75
45
67
12
-------
0.30
0.25
3 PPM n-HEXANE
PPMISOPENTANE
0.20
.0,
// 3 PPM n-BUTANE
O
•ZL
o
^0.15
^
ZD
< 0.10
i/-^
3 PPM ETHANE
3 PPM PROPANE
0.05
\-° /
• /
/
/\
\
*
0
x^
"A
AIR QUALITY STANDARD
\ °
3 PPM METHANE \
D
• —A ^ I I
0.25 0.50
0.75
1.00
1.25
1.50
INITIAL NO CONC,, PPM
A
Figure 1. Maximum Ozone Produced from Irradiation
of Paraffin/NO Mixtures
A
13
-------
Q_
DL
o
o
0
Figure 2. Reaction Profile of Irradiation
of Baseline Mixture
14
-------
0.40
0.35
0.30
8: 0.25
o
cT 0.20
O
0.15
10.10
0.05
0
4
/
o—
o 100% HC CONTROL
BASELINE
MIXTURE
. 50% HC CONTROL
80% HC CONTROL
90% HC CONTROL
0.1
0.2
0.3
0.4
- o
0.5
0.6
INITIAL NOYCONC., PPM
A
Figure 3. Maximum One-Hour Ozone Concentrations
Produced from Irradiation of Multi-
component Hydrocarbon/NO Mixtures
A
15
-------
1.8
8: 1.2
o
<:
on
O
o
O
M
O
0.6
0
BASELINE
MIXTURE
50% HC CONTROL
80% HC CONTROL
HC CONTROL
90% HC CONTROL
0.6
0.7
INITIAL NOXCONC., PPM
Figure 4. Ozone Dosages in the Irradiation of
Multicomponent Hydrocarbon/NO Mixtures
A
16
-------
0.40
0.35
0.30
^ 0.25
o
0.20
o
o
c\j
O
O
x 0.15
-------
cc.
IE
1.5
1.2
0,9
o
-------
100
* 90
i
o 80
Q
LU
70
>
0
0
TO MEET 03 STD.
I
l^
I ^TOMEETN02STD.
25 50 75
NOREDUCTION-%
100
Figure 7. Emission Reductions Necessary to Meet Federal
Air Quality Standards in the Los Angeles Basin
19
-------
100
75
50
LU
o
25
0
— x 0.5 ppm N02
\
\
\
\
\
0
I
i
i
I
).25 ppm NO,
I
25 50 75
NO REDUCTION (%)
100
Figure 8. Emission Reductions Necessary to Meet Other
Air Quality Standards in the Los Angeles Basin
20
-------
REFERENCES
1. B. Dimitriades, "Effects of Hydrocarbon and Nitrogen Oxides on
Photochemical Smog Formation," Environ. Sci. Techno!.. 6^ (1972),
p. 253.
2. "A Critique of the 1975 Federal Automobile Emission Standards for
Hydrocarbons and Oxides of Nitrogen," Panel on Emissions Standards
and Panel on Atmospheric Chemistry, Committee on Motor Vehicle
Emissions, National Academy of Sciences (1973).
3. "Air Quality and Automobile Emission Control," a report by the
Coordinating Committee on Air Quality Studies, National Academy
of Sciences, National Academy of Engineering, September 1974.
4. "The Effects of Proposed Light-Duty Motor Vehicle Emission Standards
on Air Quality," Staff Report 74-21-4A, Air Resources Board, State
of California, November 13, 1974.
5. R. E. Neligan, "Hydrocarbons in the Los Angeles Atmosphere," Arch.
Environ. Health. 5^ (1962), p. 581.
6. A. P. Altshuller and T. A. Bellar, "GC Analysis of Hydrocarbons in
the Los Angeles Atmosphere," J. Air Pollut. Control Assoc.. 13
(1963), p. 81.
7. E. R. Stephens, E. F. Darley, and F. R. Burleson, "Sources and
Reactivity of Light Hydrocarbons in Ambient Air," Proc. Amer. Petrol
Inst., Division of Refining, 4,7 (1967), p. 466.
8. A. P. Altshuller, W. A. Lonneman, F. D. Sutterfield, and S. L.
Kopczynski, "Hydrocarbon Composition of the Atmosphere of the Los
Angeles Basin -- 1967," Environ. Sci. Techno!.. j> (1971), p. 1009.
21
-------
9. A. P. Altshuller, S. L. Kopczynski, D. Wilson, W. Lonneman, and
F. D. Sutterfield, "Photochemical Reactivities of n-Butane and
other Paraffinic Hydrocarbons," J. Air Pollut. Control Assoc., 19.
(1969), p. 787,
10. W. E. Wilson and G. F. Ward, "The Role of Carbon Monoxide in Photo-
chemical Smog. I. Experimental Evidence for Its Reactivity," pre-
sented at 160th National Meeting, American Chemical Society, Chicago,
Illinois, September 1970.
11. J. J. Bufalini, B. W. Gay, and S. L. Kopczynski, "Oxidation of
n-Butane by the Photolysis of NO,,," Environ. Sci. Techno!.. 5_
(1971), p. 333.
12. C. S. Tuesday, B. A. D'Alleva, J. M. Heuss, and G. J. Nebel, "The
General Motors Smog Chamber," Research Publication GMR-490, presented
at the Air Pollution Control Association Annual Meeting, Toronto,
Canada, June 1965.
13. R. J. Jaffe, F. C. Smith, and K. W. Last, "Study of Factors Affecting
Reactions in Environmental Chambers," Report LMSC-D401598, Lockheed
Missies and Space Company, Sunnyvale, California, April 1974.
14. M. W. Korth, A. H. Rose, and R. C. Stahman, "Effects of Hydrocarbon
to Oxides of Nitrogen Ratios on Irradiated Auto Exhaust — Part I,"
J. Air Pollut. Control Assoc.. ^4 (1964) p. 168.
15. M. C. Dodge and J. J. Bufalini, "Photochemical Smog and Ozone Forma-
tion," Adv. Chem. Ser., No. 113, American Chemical Society, 1972,
p. 232.
16. K. Westberg, N. Cohen, and K. W. Wilson, "Carbon Monoxide: Its
Role in Photochemical Smog Formation," Science. 171 (1971), p. 1013.
17. Air Quality Criteria for Hydrocarbons, National Air Pollution Control
Administration Publication No. AP-64, March 1970, p. 3-8.
22
-------
18. W. A. Lonneman, T. A. Bellar, and A. P. Altshuller, "Aromatic
Hydrocarbons in the Atmosphere of the Los Angeles Basin,"
Environ. Sci. Technol.. 2, (1968), p. 1017.
19. W. E. Morris and K. T. Dishart, "The Influence of Vehicle Emission
Control Systems on the Relationship Between Gasoline and Vehicle Exhaust
Composition," presented at ASTM Workshop, Toronto, Canada, June 24, 1970.
20. M. W. Jackson, "Effects of Some Engine Variables and Control Systems
on Composition and Reactivity of Exhaust Emissions," from Vehicle
Emissions II, SAE Progress in Technology Series, 12, 1967.
21. D. T. Wade, "Factors Influencing Vehicle Evaporative Emissions,"
from Vehicle Emissions III, SAE Progress in Technology Series, 14,
1971.
22. M. W. Jackson and R. L. Everett, "Effect of Fuel Composition on
Amount and Reactivity of Evaporative Emissions," from Vehicle
Emissions III, SAE Progress in Technology Series, ^4, 1971.
23. E. R. Stephens and F. R. Burleson, "Analysis of the Atmosphere for
Light Hydrocarbons," J. Air Pollut. Control Assoc., JT7 (1967), p. 147.
24. A. P. Altshuller, S. L. Kopczynski, W. A. Lonneman, and F. D.
Sutterfield, "A Technique for Measuring Photochemical Reactions in
Atmospheric Samples," Enyiron. Sci. Techno1. 4, (1970), p. 503.
25. S. L. Kopczynski, W. A. Lonneman, F. D. Sutterfield, and P. E. Darley,
"Photochemistry of Atmospheric Samples in Los Angeles," Environ.
Sci. Technol.. 6 (1972) p. 342.
26. "Ten-Year Summary of California Air Quality Data, 1963-1972" report
of the Division of Technical Services of the State of California Air
Resources Board, January 1974.
27. Federal Register, _38, June 8, 1973, p. 15174.
28. California Air Resources Board Bulletin, Vol. 5, December 1974.
23
-------
E. DR. THOMAS GRAEDEL
DR. BEAT KLINER
CHEMICAL KENETIC & DATA ANALYTIC
STUDIES OF THE PHOTOCHEMISTRY OF THE
TROPOSPHERE
-------
CHEMICAL KINETIC AND DATA ANALYTIC STUDIES
OF THE PHOTOCHEMISTRY OF THE TROPOSPHERE*
by
W. S. Cleveland, L. A. Farrow
T. E. Graedel, and B. Kleiner
Bell Laboratories
Murray Hill, New Jersey 07974
This presentation briefly describes some of the
results of the Atmospheric Analysis Project at Bell
Laboratories. The newly-derived information comes from
studies of the characteristics and chemical properties
of the existing atmosphere in the Northeastern United
States. The effort is ongoing and results will continue
to be made available to all interested parties.
The work at Bell Laboratories is divided into
two distinct but closely interacting areas. One of these
is the use of modern statistical techniques on large
amounts of atmospheric data; the second consists of
detailed atmospheric chemical studies. The nature of
these two areas and a few of the conclusions will now be
described.
Our chemical studies involve detailed computations
simulating the photochemical processes of the lower troposphere,
*
Transcript of talk delivered at the EPA Symposium on
the Atmospheric Chemistry of NOX, Washington, D. C.,-
February 12, 1975.
-------
- 2 -
A summary of some of the factors treated in these computations
is given in Figure 1. Our basic approach is to examine
the interactive chemistry of the atmosphere in detail.
To this end we include comprehensive treatment of O-H-N
chemistry, an extensive set of reactions which represent
the chemistry of hydrocarbons, and a reaction set involving
the gas-phase chemis-try of sulfur compounds. Since the
heterogeneous chemistry of gases and aerosols is potentially
important, evaluation of those effects is also included.
To apply these chemical calculations to the
case of urban atmospheres, a number of additional factors
must be evaluated. Our calculations treat the Northern
New Jersey-New York City metropolitan region. We have
derived information on bulk, air flow from analyses of
National Weather Service data, and on emission inventories
from various governmental surveys. A final consideration
is the use of exact numerical methods for the solution of
the coupled differential equations that result.
We have completed coupled calculations as
described above for three adjacent counties in Northern
New Jersey (Morris, Essex, and Hudson). The degree to which
the calculations represent actual atmospheric processes
can be assessed by comparison of the results with
atmospheric air quality measurements. For this purpose,
we use data from days that have been carefully selected
-------
- 3 -
so that the meteorological and seasonal conditions match
those used in the computations. On Figure 2 are comparisons
of such data for 03, NO, and NO, with calculations for
Hudson County, New Jersey. Both the hour-by-hour medians
of the selected data (triangles) and the computations (solid
lines) show the typical sequence of an early morning NO rush-
hour peak, a slightly later N02 peak, and the midafternoon
ozone peak.
Figure 3 compares computed diurnal peak values for
minor constituents with such measurements as exist. Since
the chemistry of nitrogen compounds is particularly interesting,
the agreement for those species is gratifying. PAN is pre-
dicted to be ^5 ppb, a value very close to that measured by
Lonneman of EPA in Hoboken, N. J, For nitric acid we calculate
M. ppb. No New Jersey measurements exist, but Spicer reports
values of ^2 ppb in St. Louis, an urban atmosphere that
probably bears many similarities to that of northern New
Jersey. The only nitrous acid measurements are those of
Nash in England; his measurements and our calculations are
both. ^3 ppb. Our calculations for these stable species have
not included the effects of heterogeneous (i.e. gas-aerosol)
removal. Since some heterogeneous removal probably occurs,
the concentrations represent upper limits to those actually
produced by atmospheric chemical processes.
On the basis of the demonstrated agreement
between computations and data, we conclude that our results
capture at least the essential processes of urban atmos-
pheric photochemistry. We therefore feel that chemical
-------
- 4 -
conclusions can be drawn from our results, and that they
are applicable to the tropospheric processes of urban
areas. Four of these conclusions are listed below by
title and shown on Figure 4; they are described and
defended in detail in technical publications which we
have issued or which are in preparation.
•
1. NOX~°3 chemistry in the atmosphere is
significantly influenced by aerosol-radical interactions.
We feel, therefore, that chemical calculations that omit
heterogeneous chemistry cannot accurately represent the
chemistry of the urban troposphere.
2. Sulfur chemistry is not likely to affect
NO -0, chemistry to an important degree (although the
X J
transformations of sulfur compounds are, of course,
important in themselves).
3. CO and CH4 are unimportant species in
urban photochemistry. (This statement may not hold, however,
for the atmospheric chemistry of rural areas.)
4. The most important effect of hydrocarbons
on. O3 concentrations is nitric oxide oxidation by aldehyde-
produced RO2- Hydrocarbons and hydrocarbon radicals
interact with all phases of the chemistry, however, and as
a succinct summary we can best say that changes in hydro-
carbon concentrations and species will profoundly affect
virtually every tropospheric chemical species.
-------
- 5 -
The Bell Laboratories statistical investigation
of photochemistry- in the Northeastern United States was
started by building up a data bank which now contains
approximately 3.5 mill, measurements collected from local,
state, and federal agencies and private institutions. As
an example the map of the Northeastern United States in
Figure 5 shows all sites from which we have hourly ozone
measurements for May-September 1974 (crosses) and the sites
where we have meteorological measurements (circles). All
of this data is interfaced with a highly efficient data
management system which allows rapid access for extensive
statistical analysis.
The remainder of this paper describes two of the
results arising from our statistical analyses of these air
quality data. The first is the finding of the so-called
Sunday-effect. About two years ago, when this investigation
started, there was widespread belief that there exists a
direct and positive relationship between the quantity of
primary pollutants emitted during the morning rush hours
and the maximum 1-hour ozone concentrations later on in
the same day. Since we can hardly run designed experiments
with society, it is of course very hard to determine if
such a relationship really exists; however, each week a
pseudo-experiment takes place, in which the sources of
-------
- 6 -
primary pollutants are varied due to the changes in traffic
patterns on different days of the week.
To verify that there is a reduction of primary
pollutant emissions on Sunday mornings, we compared the
distributions of average values from 5 a.m. to 1 p.m. on
Sundays with the distributions of the averages from 5 a.m.
to 1 p.m. on workdays for all air contaminants and meteorological
variables at all sites for which we had data. We also
compared the distributions of the one hour daily maximum
of ozone between 1100 and 1800 hours and the 0700 measure-
ments of mixing height on Sundays and workdays. This was
done by means of a statistical technique called a quantile-
quantile (Q-Q) plot. The big advantage of the Q-Q plot is
its ability to compare all aspects of two distributions,
as opposed to means, which deal only with one particular
aspect. On the Q-Q plot the quantiles of one set of data
(in this case the Sunday values) are plotted against the
corresponding quantiles of the other set of data (in this
case the workday values). If the distributions are nearly
the same, then the points of the plot lie nearly along
the straight line Y=X.
Such Q-Q plots were made for the air quality
and meteorological data described above. (Several of these
-------
- 7 -
are shown in Figure 6.) For each of the variables the
following patterns were consistently observed at all
sites. The Sunday quantiles of NO, N02, CO, nonmethane
hydrocarbons, aerosols, and total hydrocarbons are markedly
lower than the workday quantiles, since on the Q-Q plots
all these points are well below the line Y=X. The quantiles
•
for aldehydes and CH. are slightly lower on Sundays than
on. workdays, whereas S02 shows no consistent pattern. The
O., maxima are only slightly higher on Sundays, whereas 0.,
averages are markedly higher. For all the meteorological
variables the workday and Sunday quantiles are similar
except solar radiation, mixing height, and vertical sigma,
which have noticeably higher Sunday quantiles.
Summarizing, we note that the reduction in the
concentrations of primary pollutants from 5 a.m. to 1 p.m.
on Sundays may be regarded as a regional experiment to
shed light on the effectiveness of reducing the O^ concen-
tration by a morning reduction of primary pollutants.
Since the 03 concentrations show little change in this
experiment, it would appear that serious questions are
raised about this reduction procedure.
The second result involves the transport of
ozone from the Philadelphia-Camden urban complex.
-------
- 8 -
Chemiluminescent ozone measurements In Ancora,
New Jersey, a nonindustrial, low traffic density site
37 km southeast of the center of the Camden-Philadelphia
urban complex, were an enigma since monitoring began there
in 1973 by the New Jersey Department of Environmental
Protection. It had been shown in an earlier study which
we published in Science that of nine sites in New Jersey
and New York, Ancora, the only nonurban site, was the one
whose daily maximum ozone concentrations exceeded the
Federal Standard of .08 ppm most frequently between May
and September 1973. High ozone concentrations had also
been noted in other nonurban locations (some of them in
rather remote areas) by a number of other investigators.
This led to considerable concern that there was something
missing in the view that ground level ozone is the result
of man's emissions of hydrocarbons and nitric oxide and
raised the question of whether nature was a major supplier
of O.j. It seemed imperative, therefore, to try to under-
stand something about the source of the Ancora 03. An
extensive investigation, which rested heavily on a new
graphical statistical device called a moving statistic
plot, was undertaken to examine the dependence of ozone
concentrations at rural sites on prevailing wind direction.
The conclusion was that man's emissions from the Camden-
-------
- 9 -
i
Philadelphia urban complex do in fact account for some of
the ozone present in Ancora, as well as in three other
sites ranging 27 km to 49 km from the center of the
complex (see Figure 7) .
Therefore, photochemical air pollution in the
Philadelphia area has, to be regarded as a regional rather
than a local problem and ozone resulting from emissions
within the urban complex is widespread and not confined
to the complex itself.
-------
FIGURE CAPTIONS
Fig. 1 - Factors included in computations of tropospheric
chemistry.
Fig. 2 - Computed diurnal concentration variations (solid
lines) for Hudson County/ New Jersey, compared
with measured hourly median values from
observations in Bayonne, New Jersey on days
closely simulating those for which, calculations
were made.
Fig. 3 - Measured and computed peak concentrations for
minor atmospheric compounds. The calculations
are for Hudson County, New Jersey.
Fig. 4 - A summary of conclusions resulting from the
chemical kinetic calculations.
Fig. 5 - Monitoring sites included in the statistical
investigations of ozone transport. Crosses
indicate ozone measurement sites, circles
indicate meteorological measurement sites.
Fig. 6 - Quantile-quantile plots for Sundays versus
workdays.
Fig. 7 - The Camden-Philadelphia urban complex and its
environs.
-------
BTL ATMOSPHERIC PHOTOCHEMICAL MODEL
CHEMICAL COMPONENTS
Oxide of Nitrogen Chemistry
Hydrocarbon Reactions
Sulfur Chemistry
AEROSOL INTERACTIONS
BOUNDARY AND SOURCE SPECIFICATIONS
Geographical Matrix
Source Inventories
Mixing Height
Bulk Air Flow
Diurnal Variation
NUMERICAL METHODS
Figure 1
-------
Li
0 2
•4 j 6 6 O 12 14 16
HR. OF DAY
22 24
Figure 2
-------
PEAK CONCENTRATIONS FOR MINOR ATMOSPHERIC COMPOUNDS
Observed
ompound
CH2=CHCHO
CH,CHO
CH3(CO)02N02
HCHO
HCOOH
H2°2
HN02
HN03
Computed Peak
Concentration (ppm)
2.95xlO~2
2.23xlQ~2
4.67xlO~3
1.78xlQ~2
5.95X10"4
1.72X10"2
2.96xLO~3
1.36xlO~3
Peak
Concentration (ppm)
1.4xio~2
1.2xlQ~2
3.7xlO~3
e*io-3
.7X10-2
^4X10-*
3.2 xio"3
^2 xio""3
Location
Los Angeles, Cal.
Bayonns, M. J.
hoooKen, N. J.
Bayonne, N. J.
Pasadena, Cal.
Hoboken, N. J.
South England
St. Louis, Mo.
Reference
Altshuller & McPherson
J.A.P.C.A., 13, 109 (1963)
*
W. A. Lonneman, private
communication, 1974
W. S. Cleveland and B.
Kleiner, private comm. ,197
P. Hanst, private communi-
cation, 1974
Gay & Bufalini, Adv. Chem.
113, 255 U972)
Nash, Tellus, 26, 176
(1974)
D. P. Miller, private
communication, 1974
The "observed" Bayonne concentration of CH^CHO is based on the Bayonne observation of HCHO
and the assumptions that the total aldehyde/formaldehyde ratio of Altshuller and McPherson.
(1963) holds in northern New Jersey and that total aldehydes minus formaldehyde is
essentially equal to CH3CHO.
Figure 3
-------
Q)
'3
-------
-------
0.12
0.08
0.04
0.00
.g. 0.00
c
03 max.
Linden
(ppm)
OD4 0.03 0.12
3.0
2D
ID
OX)
Nonmethane
hydrocarbons
Linden
(ppm)
480
320
160
CO
.-• Elizabeth
(ppm)
"• 025
Solar radiaUon
Central Park
(langfeys)
0.15
0.05
.- • NO
*•" Elizabeth
(ppm)
160 _ 320 . ,
Workdays
480
0.0
0.0
\2
0.0" 0.1 02 03 0.4
1.6i . i • i
12
0.8
0.4
Aerosols.
Elizabeth^
. (ruds)_;
2.0
F igure 6
-------
NORR1STOWN
McGUIRCAM
FORCE MSE
ANCORA
Figu IB 7
-------
F. DR. CHET SPICER
NON-REGULATED PHOTOCHEMICAL POLLUTANTS
FROM NOx, NITRIC ACID, AND NITRATES
-------
NONREGULATED PHOTOCHEMICAL POLLUTANTS
DERIVED FROM NITROGEN OXIDES
by
Chester W. Spicer
BATTELLE
Columbus Laboratories
Presented at
THE SCIENTIFIC SEMINAR ON AUTOMOTIVE POLLUTANTS
February 10-12, 1975, Washington, D.C.
-------
NONREGULATED PHOTOCHEMICAL POLLUTANTS
DERIVED FROM NITROGEN OXIDES
by
Chester W. Spicer
BATTELLE
Columbus Laboratories
Presented at
THE SCIENTIFIC SEMINAR ON AUTOMOTIVE POLLUTANTS
February 10-12, 1975, Washington, D.C.
The topic of this discussion is nonregulated photochemical pollutants
derived from nitrogen oxides. I'll be discussing nitric acid, organic nitrates,
particulate nitrates, and particulate nitrites. I'll not be discussing gaseous
nitrites even though we know that gaseous nitrites must be formed in photo-
chemical smog. They photodissociate so rapidly that they can only be present
as transient intermediates. We will be discussing particulate
nitrites, although only briefly. We've attempted to monitor particulate nitrites
in several urban areas and we see only very low concentrations of particulate
nitrite. We don't know whether this is caused by a very low rate of formation
of particulate nitrites or whether particulate nitrites may be oxidized rapidly
either in the atmosphere or during our sampling procedures for particulate nitrate.
As I mentioned, I will be discussing particulate nitrates in some detail. We'll
also be talking about organic nitrates, primarily PAN (peroxyacetyl nitrate).
Several other kinds of organic nitrates have been identified in the atmosphere.
Particulate organic nitrates have been detected at extremely low concentrations.
Methyl and ethyl nitrate have been determined in the gas phase at sub part per
billion levels. Peroxypropionyl nitrate has been determined in certain urban
atmospheres at the few parts per billion level. Peroxybenzoyl nitrate, a very
potent eye irritant, has also been identified in smog simulations. To the best of
my knowledge, however, it has not yet been detected in urban atmospheres. The
topic of nitric acid in urban atmospheres will also be covered in some detail in
this paper.
-------
Before turning to the real atmosphere, I would first like to discuss
the smog simulation shown in Figure 1. This figure shows an irradiation of a
synthetic exhaust-nitrogen oxides mixture, plotting concentration in parts per
million on the ordinate versus irradiation time on the abscissa. The patterns
shown in the figure follow the classic symptoms of photochemical smog with NO
dropping off rapidly to very low values within the first hour of the irradiation,
N0« rising rapidly within the first hour to a peak and then dropping off fairly
rapidly thereafter. Both NO and N0_ were determined in this smog chamber run
by a continuous colorimetric procedure. We know that N02 is subject to interference by
PAN and, to some extent, nitric acid in the widely employed chemiluminescent
technique. This is an especially important interference in smog chamber systems,
so we have chosen to use the continuous colorimetric procedure which is not sub-
ject to these interferences. Ozone rises rapidly in the experiment after an
initial induction period and peaks at about 2 hours into the irradiation. Both
PAN and nitric acid show an initial induction period and then rise fairly rapidly
to a plateau between 2 and 3 hours into the experiment.
There are two measurements shown for nitric acid in Figure 1. The first
of these, denoted by the solid line, is a continuous procedure. The second measure-
ment makes use of an integrated colorimetric technique. The integrated sample was
collected over the time interval denoted by the dashed line in the figure. It
is of interest to note that the average nitric acid as determined by the continuous
technique, averaged over the same time interval as shown by the dashed line, gives
excellent agreement with the integrated colorimetric procedure.
The purpose for showing this figure is the excellent nitrogen balance
achieved throughout the smog chamber run when both PAN and nitric acid are taken into
account. The sum of NO, N02, PAN, and nitric acid is essentially constant through-
out this entire smog chamber irradiation with only a slight decrease during the
irradiation due to dilution in our smog chamber. This indicates that, at least
over these short time intervals, the initial primary products of nitrogen oxides
reactions are PAN and nitric acid.
There has been a good deal of discussion over the years as to the mechanism
of nitric acid formation. Three mechanisms which have been widely discussed are
shown below.
-------
Concent ration,ppm
33
o
rn
i—1
•
H
m >
oo
m n
CO CO
?=•-<
^ 2!
V X _ I
-'s i
HX
c m
m
V S
CO
H
U)
-------
I. 2N02 4- HO surface^ HONCL + HONO
II. N02 + HO(+M) - HONO (4M)
III. N0 + 0 - N0 + 0
N2°5 + H2° surface- 2HON02
In the first mechanism, N02 reacts heterogeneously with water to form nitric acid
and nitrous acid. In the second mechanism, NCL reacts with a hydroxyl radical to
form nitric acid, and in the third mechanism, NCL reacts with ozone to form N0~
which then goes on to form dinitrogen pentoxide. The dinitrogen pentoxide can
then react heterogeneously with water to form nitric acid. The first of these
mechanisms can be excluded as being unimportant, at least in our smog chamber work.
We see no evidence for this mechanism playing a part in nitric acid formation in
our smog chamber experiments. The second mechanism, the reaction of N0_ with
hydroxyl, does play a part in our smog chamber reactions, especially in the early
part of the run, and can account for between 20 and 30 percent of the nitric acid
that we form in many smog chamber experiments. The predominant mechanism for
formation of nitric acid, however, is the reaction of NCL with ozone to form N90,_
which can then react heterogeneously with water to form nitric acid. I would
like to emphasize that this work has been done in smog chambers and may not be
directly applicable to the atmosphere because of the different surface to volume
ratios involved.
Turning now to the real atmosphere, I'd like to discuss several differ-
ent profiles collected in over 5 weeks of sampling in the Los Angeles basin, as
shown in Figure 2. Looking first at the bottom third of the figure, we've plotted
the 5-week composited meteorological profiles. Shown in this profile are global
irradiance, a measurement of total solar intensity which we use to determine day
to day variations in sunlight intensity, wind speed, temperature, and relative
humidity. In the middle portion of the figure are shown the profiles for ozone,
NO, NO , and total nitrogen oxides. The ozone profile follows the classic pattern
-------
Los Angeles
Legend
PAN 0?020ppm
HN03O.OiOppm
Nitrogen oxides 0.200 ppm
Ammonia 0.006 ppm
Los Angeles
Legend
Ozone 0.200 ppm
Nitric oxide 0.200 ppm
Nitrogen dioxide 0.100 ppm
Nitrogen oxides 0.200 ppm
Los Angeles
8 10 12 14 16
Hour of Day
18 20 22
Global irradiance 0.900 ccl/sq cm/min
Wind speed G.OOO rnph
'Temperature 30.000 Centigrade
Relative humidity 100.000 pcrceni
FIGURE 2. AVERAGE DIURNAL AIR QUALITY AND METEOROLOGICAL PROFILE, WEST COVINA
-------
for urban photochemical smog, showing very low values during the early morning
and nighttime hours, and reaching a peak at about 2:00 o'clock in the afternoon.
The peak, on an hourly average basis, reaches about .16 ppm of ozone over this
5-week sampling interval. The NO profile rises in the morning between 6
and 8 o'clock to its maximum value, then drops off rapidly and maintains
a very low value during the afternoon hours. Once the sun goes down, the
driving force for the reactions is gone and NO, which is continuously emitted
into the atmosphere, is allowed to titrate the ozone that is still present,
so that the ozone is removed and N0_ is formed. When the ozone reaches a very
low value, as it does at about 1900 hours, the NO is permitted to rise rapidly.
The NO- profile is also shown in this figure. Nitrogen dioxide peaks at about
10:00 o'clock in the morning, approximately 2 hours after the NO peak, and
then maintains a fairly level value throughout the afternoon hours,
rising again later in the evening as the NO-0- titration occurs. The
level portion during the afternoon hours is probably somewhat in error
due to the aforementioned PAN and nitric acid interference with NO
as determined by chemiluminescent techniques. At its worst during the afternoon
hours, this interference may cause the N0_ curve to appear about 20 percent high.
Total nitrogen oxides, reported as NO , is also shown in the figure.
X
In the upper portion of the figure, we show some of the species which
are most pertinent to this paper. PAN is shown at 20 ppb full scale. PAN shows
a very low concentration during the nighttime and early morning hours, rising dur-
ing the later morning and early afternoon hours to a peak at about 2 o'clock in
the afternoon. PAN peaks at about the same time as ozone at about 20 ppb on an
hourly average basis. After the peak, PAN drops fairly rapidly. Nitric acid is
also rather low during the morning hours and nighttime hours, again rising to its
peak at about 2 o'clock in the afternoon, the same time that PAN and ozone peak.
Its maximum value occurs at about 10 ppb on an hourly average basis. Nitric acid
then drops off very rapidly after its peak. Ammonia is also shown in this profile
at 6 ppb full scale, and total nitrogen oxides is shown again for comparison
purposes.
-------
As was pointed out earlier the PAN, nitric acid, and ozone peaks all
occur at about the same time. During this 5-week study period, the correlation
coefficients among PAN, nitric acid, and ozone were all in the neighborhood of
.7 to .8. It is interesting to note that nitric acid appears to drop off much
more rapidly than PAN after their peaks. This may well be due to the fact Lh.it
there is some other sink or some additional scavenging mechanism operating on
nitric acid which does not operate on PAN.
Over the last 3 years we have monitored PAN in several cities besides
Los Angeles and the profiles from some of these cities are shown in Figure 3.
Los Angeles is again shown for comparison purposes, with PAN reaching a maximum
hourly average value of about 20 parts per billion at 2 o'clock in the after-
noon. The Los Angeles profile is the composite of 5 full weeks of sampling. The
St. Louis profile is also composited from 5 weeks worth of sampling. The PAN
concentrations in St. Louis were considerably lower than in Los Angeles on the
average. The PAN concentrations were very low during the nighttime and early
morning hours, rising somewhat during the later morning and early afternoon
hours, during the photochemical portion of the day, and dropping off again later
in the evening. The maximum concentration that we saw in St. Louis during our 5
week's sampling interval was about 17 ppb on an hourly average basis. This was
the extreme value, however, and most of the PAN values were much more on the order
of the values shown in the figure. The PAN concentrations in Dayton, Ohio, or
more specifically Wayne Township, a small suburban community 10 miles northeast
of Dayton, are shown on the bottom portion of Figure 3. The PAN concentrations
were extremely low, essentially zero during the nighttime and early morning hours,
rising very slightly during the later morning and early afternoon hours (again
during the photochemical portion of the day) and then dropping off again during
the later afternoon and evening hours.
Nitric acid profiles from several different cities are shown in Figure
4. The upper portion of this figure again shows the Los Angeles profile for
nitric acid that we saw in Figure 2. Nitric acid rises at about 2:00 o'clock in
the afternoon to its peak. The peak value occurs at about 10 ppb on an hourly
average basis. The nitric acid concentration in St. Louis is considerably more
-------
variable than that found in Los Angeles, showing several peaks and valleys
throughout the day. The average concentration in St. Louis was on the order
of 3 to 4 ppb, with some peaks reaching about 7 ppb. We are uncertain as to
the reason for the variation in the St. Louis nitric acid profile. This
variation could be due to changing meteorological conditions or it could possibly
be due to different nitric acid formation mechanisms occurring during different
portions of the day. The profile for New Carlisle, Ohio, a very small rural
community 20 miles northeast of Dayton, is shown in the central portion of
the figure. The nitric acid concentration was extremely low during the night-
time and early morning hours, rising slightly during the later morning and early
afternoon hours and interestingly, rising again during the later evening hours.
The Wayne Township profile is also shown in this figure. Very low
nitric acid values were found in Wayne Township with a slight
peak during the 8 to 10 a.m. portion of the day. In downtown Dayton,
Ohio, the last profile shown in this figure, the nitric acid concentrations were
considerably higher than shown for New Carlisle and Wayne Township, with an in-
crease of nitric acid during the night, a very sharp increase occurring between
9 and 10 o'clock in the morning, and a fairly broad plateau during the afternoon,
photochemical, portion of the day. I should point out, however, that this down-
town Dayton profile is based on only 11 sampling days and two of those days showed
considerably higher nitric acid than the other 9 days. It may well be that if we
sampled for a longer period of time in Dayton, Ohio, that the average nitric acid
values would be considerably less than indicated in this profile.
Turning now from gas phase to aerosol data, I would like to discuss aeroso]
composition on a weight percentage basis, as shown in Table 1. This table displays
the aerosol composition based on 5 weeks of sampling in St. Louis, Missouri, 5
weeks of sampling in West Covina, California (in the Los Angeles basin), and 4
weeks of sampling in Dayton, Ohio. The data are divided into the total aerosol
composition and the large particle composition for particles greater than 2-1/2
micrometers in diameter. I'd like to concentrate specifically on the total aerosol
composition. As shown in the table, the ammonium values for St. Louis, West
Covina, and Dayton are all very similar for the total aerosol composition, averag-
ing about 4.7 weight percent. The nitrite values were extremely low, essentially
undetectable in many cases, as shown by dashed lines in the table.
-------
20
16
CL
<
CL
o
St. Louis
o-o-o
20
16
12
8
Dayton (Wayne Township)
8 10 12 14 16
Hour of The Day
20 22 24
FIGURE 3. PAN PROFILES BY CITY
-------
12
8
Los Anodes
-O
QL
o.
to
o
12
8
New Carlisle
12
8
Wayne Township
12
8
0
Downtown Dayton
6 8 10 12 14 16 18 20 22 24
Hour of the Day
FIGURE 4. NITRIC ACID PROFILES BY CITY
-------
11
TABLE 1. AEROSOL COMPOSITION
(Weight Percent)
St. Louis, Missouri
Average Total Aerosol
Large Particles (>2.5 jum)
Average Total Aerosol
Larga Particles (>2.5 jum)
Average Total Aerosol
Large Particles (>2.5
NHj NC>2
4.7
0.55 0.001
N03
0.62
2.6
C
19.0
14.6
H
3.6
1.8
N
4.6
1.5
I/Vest Covina, California
NHj NOg
4.7
0.63 0.001
Dayton, Ohio
NHj N02
4.6
1.2
N05
1.7
4.8
N05
0.40
7.7
C
19.4
12.6
C
12.0
9.6
H
3.8
1.8
H
2.5
1.5
N
5.3
2.2
N
4.3
2.1
-------
12
We do nol. kno,. at tlili, time ..Uether tl.e nitrite concentration it; low because the rate o
nitrite formation is very low or because nitrite is oxidized to nitrate in the atmosptu
The carbon and hydrogen values arc not particularly pertinent to the topic of this
paper and will not be discussed here. The total nitrogen value shown in the last
column of the table is the total aerosol nitrogen by a combustion technique. The
magnitude of the total aerosol nitrogen value is similar for St. Louis, West
Covina, and Dayton. Even the large particle percentages are fairly similar for
these three cities. Later in this paper we will discuss the composition of this
total aerosol nitrogen as it relates to ammonium and nitrate compositions. Turn-
ing now to the nitrate aerosol values, we can see that the weight percentage nitrate
is very similar for St. Louis and for Dayton, Ohio, at 0.6 and 0.4 weight percent.
The value for West Covina is considerably higher, almost a factor of three higher,
and this is consistent with what other researchers have found in the Los Angeles
basin, i.e., the Los Angeles basin is usually subject to a higher nitrate burden
than most other urban areas. There are two areas, however, in which these data are
inconsistent with the work of many previous investigators. xhe first discrepancy
involves the fact that all of our nitrate values are considerably lower
than have been found by many investigators for these same urban areas. A second
area of disagreement relates to the fact that our data are showing that nitrate
is predominating in the large particle size range rather than in the submicron
size range that many investigators have reported previously. We believe that
these discrepancies can be explained in large part by the fact that gaseous nitric
acid can be adsorbed or can react with many of the filter materials used by previous
investigators to determine particulate nitrate. The adsorption or reaction of
gaseous nitric acid with the filter material would show anomalously high particulate
nitrate values and could well bias the size distribution assumed for particulate
nitrate.
Expanding on this filter interaction phenomenon, there are two kinds of
filter interactions that should be considered. The first of these involves the re-
action of nitrogen dioxide with filter materials. This is a topic that has been
discussed in the past. We've seen no evidence for this kind of an interaction in
our studies either in the laboratory or in the field. We have, however, seen con-
siderable evidence for the reaction of nitric acid with certain filter materials,
specifically glass fiber filters. It does appear that gaseous nitric acid can be
-------
13
removed by glass fiber filters which have alkaline surface characteristics.
The removal of gaseous nitric acid by the filter medium would increase the
apparent concentration of particulate nitrate and affect the apparent nitrate
size distribution. In laboratory studies we have shown that quartz tissue
filters, which are essentially neutral in terms of pH, do not remove gaseous
nitric acid from the air,but that glass fiber filters do remove nitric acid from
the air stream. In very brief experiments we've also shown that cellulose-type
filters also remove nitric acid from the atmosphere and indeed, researchers at
the National Center for Atmospheric Research have been using cellulose filters
to collect gaseous nitric acid from the stratosphere. Apparently cellulose
filters are such efficient scrubbers of gaseous nitric acid that they can actually
be used as collection media. I would like to emphasize that we've only carried
out a limited number of experiments on this phenomenon and certainly much more
work needs to be done to determine whether these filter interactions are important.
We will be continuing work in this area in our laboratory in the coming months.
The last topic that I would like to discuss involves the aerosol nitro-
gen balance. Table 2 shows aerosol data collected over 5-week sampling periods
in St. Louis, 5 weeks in New York City, 2 weeks in Pomona, California, and 4 weeks
in Dayton, Ohio. The right hand column shows the average aerosol nitrogen, as
determined by an independent combustion technique, which can be accounted for as
ammonium-nitrogen and nitrate-nitrogen. The nitrogen accountability is fairly
consistent among these six cities and averages about 75 percent, indicating that
very roughly 3/4 of the aerosol nitrogen can be easily accounted for by the known
species ammonium and nitrate.
-------
14
TABLE 2. AEROSOL NITROGEN BALANCE
City
St. Louis, Mo.
West Covina, Calif.
Columbus, Ohio
New York, N.Y.
Pomona, Calif.
Dayton, Ohio
Average Aerosol Nitrogen
Accounted for as IVH^
and NOg, percent
82.5
73.6
73.6
75.8
70.7
79.0
-------
G. DR. WILLIAM LONNEMAN
PAN LEVELS
-------
Copies of this paper were unavailable for printing. Copies of the
transcript of this portion of the seminar are available for purchase from:
Ace-Federal Reporters, Inc.
415 2nd Street, N. E.
Washington, D. C. 20002
(202) 547-6222
-------
H. DR. R.A. SAUNDERS
DOMMENTARY CONCERNING A
RAINWATER ANALYSIS
-------
COMMENTARY CONCERNING A RAINWATER ANALYSIS*
R. A. Saunders
A paper entitled "Identification of Some Organic Smog Components Based
on Rainwater Analyses" by R. A. Saunders, J. R. Griffith, and F. E. Saalfeld
was discussed by me at the EPA hearings last week at which time that paper
became a part of the official records of the hearing. This morning I want
to talk with you briefly about that paper at the suggestion of the Chairman
of last week's hearings. I would like to tell you why NRL happened to make
that analysis and describe how the analysis was performed. I will also discuss
the results of that work and make some comments concerning our explanation of
those results.
First of all, the Naval Research Laboratory was interested in developing
sensitive techniques for the analyses of trace organic contaminants in water
as part of the Navy's pollution abatement program. Having developed those
techniques we were naturally interested in applying them to samples of
particular interest. For example, we looked at the trace contaminants in D.C.
Municipal water, in distilled water, in Potomac River water and other river
waters of interest to the Navy, and in rainwater. During the period we were
making those analyses, in August 1973, outdoor air temperatures were running rather
high and we had been experiencing a series of photochemical oxidant summer smog
alerts. We wished to determine whether or not our analytical method would reveal
the presence of trace organic contaminants in rainwater and in what those
contn-amn+s Plight be. Fe deliberately chose a time when a neriod of haze and low
visibility, of several days duration, terminated with a rainfall. The particular
rainfall we sampled was a very gentle rain and we collected during the first hour
*- This manuscript was transcribed from a tape recording of remarks which were
presented extemporaneously.
-------
or two.
This kind of water analysis can be performed in several different ways.
The modification we used for the August rain sample was to strip out the organic
contaminants with helium. The helium is then passed through a liquid nitrogen
cooled trap in which the organic phase is condensed and the helium is then
exhausted to the atmosphere. The recovered contaminants were transferred into
;>
the inlet system of a gas chromatograph-mass spectrometer combination. The
chromatographically resolved components were identified one at a time by means
of their mass spectra.
We realize that the particular technique I just described will not permit
detection of low molecular weight hydrocarbons because those compounds are not
condensable. If we had been interested in detecting such compounds as carbon
monoxide, methane, ethylene or propylene we would have used a different variation
of this technique. A method suitable for detecting such compounds in seawater
was perfected and published by Swinnerton and Linnebom of NEIL. We were not
concerned with such compounds for this application , however, but only with
compounds of higher molecular weight.
The results we obtained from the rainwater analysis were so unusual and •
unexpected that we felt they should be published at once. Our analysis revealed
methyl furan as the major component of the rainwater and traces of aromatic
hydrocarbons such as benzene, toluene, and xylenes at much lower concentration.
The concentration of the methyl furan exceeded that of the aromatic hydrocarbons
by a factor of approximately 100. We attributed the methyl furan to photochemical
decomposition reactions of naturally-occurring hydrocarbons in the air. We
attributed the aromatic hydrocarbons to anthropogenic sources, chiefly the exhaust
from automobiles.
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I'm sure many of you have been to the Blue Ridge Mountains or The Great
Smokies and have seen the hazes that shroud those mountains frequently.
Dr. F. W. Went discussed those hazes at length in articles -which appeared in
the Proceedings of the National Academy of Sciences in the early 1960s. He
calculated that worldwide the astonishing quantity of % billion tons per year
of .reactive hydrocarbons are emitted into the air by vegetation. The Appalachian
area is a rich source of such emissions. When temperatures are very'high,
however, as they were in August 1973, and accompanied by the right kind of
weather system, hydrocarbons are emitted from vast areas of vegetation all the
way from the mountains to the coast. On irradiation by sunlight, these hydro-
carbons coalesce and agglomerate as discussed by Dr. Went. Each liquid droplet
of the particulate contains a mixture of all those hydrocarbons in the air
which are stable in the liquid state under the ambient conditions. Those compounds
undergo photochemical reacrions in sunlight and in the presence of oxides of
nitrogen, which occur naturally as well as anthropogenically, to form ozone,
other photochemical oxidants, and various hydrocarbon decomposition products.
We believe that the methyl furan we found was one such decomposition product.
Automobile exhaust contains a great many aliphatic and aromatic hydrocarbons
which embrace a wide range of .molecular weights. The aromatic hydrocarbon fraction,
however, probably accounts for \ to \ of the total hydrocarbons in automotive
exhaust. In our interpretation of the meaning of our rainwater analysis we are
using the aromatic hydrocarbons as a surrogate for the total contribution of
automotive exhaust. Our measured ration of 100:1 means that naturally-produced
hydrocarbons rather than automotive hydrocarbons were the major contributor to
the August 1973 smog.
-------
- k
Is it fair to relate the concentration of the hydrocarbons, as .we.detected
them, in the rainwater, to the concentration of the same hydrocarbons in the air?
Some people think the answer should be no, but we disagree. We disagree for this
reason. The solubility of methyl furan is approximate]^ the same as the solubility
of the lighter aromatic hydrocarbons. These compounds exist in the air as
particulates with each haze particle containing a mixture of the components.
Since the components we are discussing have roughly the same solubilities in
water, they are removed from the air by rainwater in the same proportion in which
they existed in the haze droplet. The efficiency with which these particles are
removed from the air may be low, but it is sufficient to permit detection by our
method of analysis. The efficiency of recovery of these compounds from rainwater
by helium purging is also approximately comparable because of their similar
solubilities. The aliphatic hydrocarbons in automotive exhaust have a much
lower solubility than the aromatic hydrocarbons and therefore will not be
detected by this method of analysis. That is unimportant, however, even though
aliphatic hydrocarbons comprise the major porti-jn of automobile exhaust, because
our conclusion, as I said before, rests on the fact that the soluble aromatic
hydrocarbon fraction serves as the surrogate for the total contribution of
automotive exhaust.
Our conclusion concerning the August 1973 smog may be controversial, but
it is supported by the conclusions of other workers who studied the same weather
system. Namely, Dr. Bandy in Virginia, who you will hear in a few minutes, and
Stasiuk and Coffee of New York. Dr. Bandy used carbon monoxide as a surrogate
for automobile emissions. He reported a ration of natural hydrocarbons to
automotive hydrocarbons greater than one order of magnitude. Our work indicated
two orders of magnitude. The conclusions based on these two analyses are very
-------
similar. Stasiuk and Coffee in New York reported a 20$ hydrocarbon contribution
from automobiles and an Qo% contribution of hydrocarbons from other sources which
they did not identify.
All of this indicates that there is a lot yet to be learned concerning the
relative air concentrations of naturally-occurring hydrocarbons and anthropogenic
hydrocarbons in rural and urban areas. Over wide areas, including urban areas,
there appear to be times when natural hydrocarbons completely overwhelm the
hydrocarbons produced by man's activities
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I. DR. ALAN BANDY
STUDIES OF THE IMPORTANCE OF BIOGENIC
HYDROCARGON EMISSIONS TO THE PHOTOCHEMICAL
OXIDANT FORMATION IN TIDEWATER, VIRGINIA
-------
STUDIES OF THE IMPORTANCE OP BIOGENIC HYDROCARBON
EMISSIONS TO THE PHOTOCHEMICAL OXIDANT FORMATION IN
TIDEWATER, VIRGINIA
Dr. Alan R. Bandy
Associate Professor of Chemistry
Old Dominion University
Norfolk, Virginia
Presented at the Scientific Seminar on Automotive Pollutants
Sponsored by the Environmental Protection Agency
February 12, 1975
Washington, D. C.
-------
Introduction
During the summer and fall of 1973? ozone levels in Tidewater, Virginia
exceeded the National Primary Standard of 0.08 ppm (one hour average) on at
least 200 occasions. Readings higher than 0.15 ppm were common. Analysis of
data from monitoring stations distributed over the Tidewater area showed that
the ozone layer over this area was nearly uniform.
Our studies in the Tidewater area in the summer and fall of 1973 showed
that CO levels were normally below 1.5 ppm which included data from monitoring
stations in downtown Norfolk. Little or no correlation of CO levels with rush
hour traffic was observed. These data should be contrasted to CO levels of 2 to
30 ppm and a strong correlation of CO levels with rush hour automobile traffic
which were found in large urban areas such as St. Louis and Los Angeles. Since
CO was thought to be a reliable tracer for mobile source emissions, these data
were used as evidence that the reactive hydrocarbon loading in these large cities
was dominated by mobile source emissions. Application of this argument to
Tidewater CO data leads one to the conclusion that mobile sources of photochemically
reactive hydrocarbons are much less important in the Tidewater area than in the
large urban areas. Therefore we were led to consider other sources for the
reactive hydrocarbons responsible for the photochemical oxidant formation, Biogenic
sources of reactive hydrocarbon emissions were investigated first.
Heavily forested areas lie south, west and northwest of the Tidewater area
of Virginia. South of this area there is a sharp change from suburban to heavily
forested areas. This heavily forested area is the northern portion of the Great
Dismal Swamp.
The location of the two sites studied are shown in Figure 1. Site 1 is
designated the Dismal Swamp site since it is located on the north edge of the
Dismal Swamp. This area is a heavily forested area dominated by Atlantic White
Cedar and Red Maple.
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Site 2 is located near the mouth of the Nansemond River in a primarily
agricultural area. Forested areas lie to the south and west. Heavily populated
areas lie to the north (Newport News and Hampton) and east (Norfolk).
Experimental
Ambient air hydrocarbons were sampled using the stainless steel traps shown
in Figure 2. The traps were cleaned by heating them to 25>0°C followed by a purge
cycle with hydrocarbon free N2 gas. The traps were readied for field use by
evacuation to 10" torr.
Samples in the field were taken by immersing the trap in liquid nitrogen and
opening a metal filling valve on the trap. The flow rate (50 cm-yminute) was
regulated with a sonic capillary so that the volume of the air sampled could be
calculated from the length of the sampling period (approximately seven minutes).
To prevent formation of liquid oxygen the sample pressure in the trap was not
allowed to exceed .5 atm.
A schematic diagram of our laboratory apparatus for gas chromatographic
analysis of the hydrocarbon samples is shown in Figure 3- The stainless steel
traps were connected to the injection system of the gas chromatograph by 0.25 inch
swagelock connectors. All stainless steel bakable high vacuum valves were used
throughout the system so that contamination was not a problem. The injection
system was heated to 100°C to insure complete transfer of the hydrocarbons to
the column.
The sample was transferred from the trap to the column by cooling the
column to -70 C, heating the trap to 100 C, and then diverting the carrier gas
(nitrogen) so that it flowed through the trap and column (1$0 ft. OV101-C0880
Scott Capillary Column). The temperature of the column was then programmed from
o
-70 to 120 C to release the hydrocarbons. A flame ionization detector was used,
providing a detectivity after the concentration step of about 100 parts-per-
trillion. The C^,C2, and Co hydrocarbons were not retained by this column. All
-------
calibrations were carried out with a methane in nitrogen standard. Concentration
data reported here are relative to methane in ppb carbon (ppbC). Nonmethane
hydrocarbon concentrations were obtained (including C^ and higher hydrocarbons)
by summing individual hydrocarbon concentrations.
Results and Discussions
A total of 13 duplicate samples were taken at site 1 during the period
April 15 tc July 2, 197U. Most samples were taken at 10:30 EOT. Nonmethane
hydrocarbon loadings ranged from 236 to 692 ppbC with an average value of 14+0
ppbC. Maximum concentrations (ppbC) for the monoterpines were 1.2 for cymene,
12 for o( -pinene, U.O for @ -pinene, 10 for mycrene and ij..O for limonene. These
monoterpines contributed 3.8 * 1.6% or about 16 - 6 ppbC to the nonmethane hydro-
carbon loading during the period April 15 to June 2^, 197U. After this date the
contribution for monoterpenes decreased to a negligible value.
Ten duplicate samples were taken at site 2 during the period June 20 to
July 7, 1971;. Nonmethane hydrocarbon levels ranged from 236 to 629 ppbC which
is about the same as for site 1. The maximum monoterpene concentrations were 9-3
for cymene, 9.3 for ^-pinene, 1.6 for ^ -pinene, 7.1; for myrcene and 0.60 for
limonene. The mcnoterpenes at this site contributed 1;.3 - 1% or 15.7 ppbC to the
nonmethane hydrocarbon loading during the period of June. Like site 1 this
contribution of monoterpenes to the nonmethane hydrocarbon loading became negligible
in July.
Apparently the nonmethane hydrocarbon levels at these two rural sites were
above the National Primary Standard during most of the sampling period. Although
the monoterpenes represent only about 5% of the nonmethane hydrocarbon loading,
this is a highly reactive fraction that represents a significant percentage of the
compounds classified as very reactive hydrocarbons. It should be noted that the
-------
monoterpene loading represents a lower bound to the biogenic fraction of the
hydrocarbon loading. The contribution of this fraction might be considerably
larger. The decrease in importance of the biogenic fraction in July could
result from a combination of increased destruction rate due to the increased
photochemical activity and lowered emission rates of the biogenic material
during summer.
-------
Figure 1. Locations of the Dismal Swamp (Site 1)
and Nansemond County (Site 2) Sites
which were sampled during this study of
ambient air hydrocarbons.
-------
-------
Figure 2. Stainless steel traps used in obtaining
ambient air samples of hydrocarbons.
Sonic capillaries (50 ml/min) were
used for flow control.
-------
BLEED-OFF
VALVE
HYDROCARBON
FREE N2
INTAKE
VALVE
MOLECULAR
SIEVE
TRAP
EXHAUST
VALVE
-------
Figure 3. Manifold for transfer of hydrocarbon
sample from the stainless steel trap
to the column of the gas chromatograph.
-------
II
CARRIER
GAS
EXHAUST
ADSORPTION
PUMP
TRAP
ssssssss
TO G.C
COLUMN
HEATING
BOX
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SECTION 6
APPENDIX
-------
A. COVER LETTERS
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UNIVERSITY OF CALIFORNIA, RIVERSIDE
BERKELEY • DAVIS • IRVINE • LOS ANGELES • RIVERSIDE • SAN DIEGO • SAN FRANCISCO
SANTA BARBARA • SANTA CRUZ
OFFICE OF THE DIRECTOR
STATEWIDE AIR POLLUTION RESEARCH CENTER
RIVERSIDE. CALIFORNIA 92502
February 14, 1975
Dr. Herbert Wiser
Environmental Protection Agency
401 "M" Street SW
WSMW 919, RD 682
Washington, D.C. 20460
Attention: Dr. Hap Thron
Dear Herb and Hap :
Here is the final revised version of my talk. It is identical in
content but somewhat more polished in form than my presentation. I very
much enjoyed the seminar.
rdially yours,
Jame$ N. Pitts, Jr.
tor
JNP:pan
Enclosure
P.S. We are including Xerox copies of the availabl
and diagrams. However, since you have the
slides and maybe you are proposing to use
these to make prints and incorporate them
in the talk, I have asked Alan Lloyd to
call you, Hap, at the beginning of next
week to clarify this matter.
JNP
igures
-------
UNIVERSITY OF CALIFORNIA, RIVERSIDE
BERKELEY • DAVIS • IRVINE • LOS ANGELES • RIVERSIDE • SAN DIECO • SAN FRANCISCO
SANTA BARBARA • SANTA CRUZ
OFFICE OF THF DIRECTOR
STATEWIDE AIR POLLUTION RESEARCH CENTER
RIVERSIDE. CALIFORNIA 92502
February 23, 1975
Dr. Herbert L. Wiser
Deputy Assistant Administrator
for Environmental Sciences
Office of Research and Development
U. S. ENVIRONMENTAL PROTECTION AGENCY
Washington, DC 20460
Dear Herb:
As indicated by telephone to your office on Friday, I am enclosing a
revised statement to be included in the published transcript of the Scientific
Seminar on Automotive Pollutants sponsored by the U. S. Environmental Protec-
tion Agency on February 10-12, 1975.
I am including a complete set of black and white prints, with the
figure numbers indicated in pencil on the reverse side and a list of figure
captions.
Thanks again for the opportunity to be a part of this important Seminar.
CordiaWv yours,
ffes N. Pitts, Jr.
Director
JNP:djf
Encls.
-------
UNIVERSITY OF CALIFORNIA, RIVERSIDE
A
BERKELEY • DAVIS • IRVINE • LOS ANGELES • RIVERSIDE • SAN DIECO • SAN FRANCISCO ((feW'-i^^Kc)) SANTA BARBARA • SANTA CRUZ
OFFICE OF THF DIRECTOR RIVERSIDE, CALIFORNIA 92502
STATEWIDE AIR POLLUTION RESEARCH CENTER
February 28, 1975
Dr. Herbert L. Wiser
Deputy Assistant Administrator
For Environmental Sciences
Office of Research & Development
U. S. ENVIRONMENTAL PROTECTION AGENCY
Washington, DC 20460
Dear Herb:
Enclosed is a full-blown print which I would appreciate your substr
tuting in the manuscript sent you on February 23 for Figure 5. I could
only send you a Xerox copy last Sunday, but I hope you will be able to
use this now in place of the one sent to you then.
Many thanks for your assistance.
Cordially yours,
James N. Pitts, Jr.
Di rector
JNP:djf
Enc.
-------
NATIONAL RESEARCH COUNCIL
ASSEMBLY OF LIFE SCIENCES
2101 Constitution Avenue Washington, D. C. 20418
DIVISION OF MEDICAL SCIENCES
February 18, 1975
Dr. Herbert L. Wiser
Deputy Assistant Administrator
for Environmental Sciences
U.S. Environmental Protection Agency
Washington, D. C. 20460
Dear Dr. Wiser:
As requested in your letter of February 14, 1975, I am
enclosing a copy of my paper.
Sincerely,
/ John Redmond, Jr. v
I Professional Associate
Enclosure
The National Research Council is the principal operating agency of the National Academy of Sciences and the National Academy of Engineerin
to serve government and other organizations
-------
UNIVERSITY OF NORTH CAROLINA
AT
CHAPEL HILL
_ , i .«..„. February 19, 1975 chapei HIII, N.C.
Institute for Environmental Studies J ' 27514
(919) 966-1175
Herbert L. Wiser
Deputy Assistant Administrator
for Environmental Sciences
U.S. Environmental Protection Agency
Washington, B.C. 20460
Dear Herb:
I enclose a copy of my paper "Health Rationale for the Existing Mobile Source
Emission Standard for Nitrogen Oxides" presented on February 10, 1974 at the
Scientific Seminar on Automotive Pollutants sponsored by the U.S. Environmental
Protection Agency. Although I handed out copies of this paper at the time of
my do I Ivory, Che i*nr. JONCC! jwp^r liftH onu corrupt Jon in if, on the page after the
summary, in the first line of the last pnrflgraph t hp word "l^fl" haw IIHBII changed
to "right". Thus the phrase reads "The far right column of table 1 shows the
maximum 1-hour N02 concentration". My slides were made directly from the tables
in the text, and I therefore have no enlarged images of these slides.
I appreciate the opportunity to make a presentation at the Seminar.
Sincerely yours,
Carl H. Shy,
Director
CMS/bs
Enclosure
-------
MEDICAL DEPARTMENT
4,
Gu" Bllll<""«
Pittsburgh. Pa I5230
Dr. Herbert L. Wiser
Deputy Assistant Administrator
for Environmental Sciences
Office of Research and Development
U. S. Environmental Protection Agency
Washington, D. C. 20460
Dear Dr. Wiser,
I have at hand your letter of February 14 concerning
texts of the papers presented at the Seminar on Auto-
motive Pollutants held in Washington in February.
Unfortunately, as I was busy moving from Montreal to
Pittsburgh in late February, it has not been possible
for me to provide a copy of my presentation sooner.
I enclose one herewith and hope it is not too late for
inclusion in the record.
Yours sincerely,
Harold N. MacFarland, Ph. D.
Director of Toxicology
HNM :pwm
Attachment
-------
R
II I KcMMU'll lll'.llllllC
Hi West .}(•> Slieel rhi<:;ii)o Illinois 60616
312/221)9080
February 25, 1975
Herbert L. Wiser, Ph.D.
Deputy Assistant Administrator
for Environmental Sciences
US Environmental Protection Agency
Washington, D.C. 20460
Dear Dr. Wiser:
As per your letter of February 14, I am enclosing a "clean"
copy of paper presented at the Scientific Seminar on
Automotive Pollutants . I do not have the originals of
Slide 1 and 6, but I hope you have copied the slides I
left with Mr. Thron. Please let me know if I can be of
further help.
Sfhcerely yours,
Richard Ehrlich
Director
Life Sciences Research
RE/sf
Enc.
-------
X
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
National Environmental Research Center
Research Triangle Park, North Carolina 27711
February 24, 1975
Dr. Herbert Wiser
Environmental Protection Agency
Acting Deputy Assistant Administrator
Office of Environmental Sciences
RD-682, Room 919A
Washington, DC 20460
Dear Dr. Wiser:
Enclosed please find a copy of the paper entitled Recent Epidemi-
ologic Studies on Health Effects Related to Exposure to NO presented
at the scientific seminar on automotive admissions.
rely yours,
ian G. French, Ph.D
Epidemiologist
luman Studies Laboratory
-------
April 6, 1975
Ms.Valerie Kazarian
U.S.Environmental Protection Agency
Washington, DC 20^60
Dear IV»R.Kazarian,
Thank you for your reminder of Kerch 27. because my son Paul, who
delivered my paper, turned a copy in at the seminar, I thought that
the intent of Dr. Wiser's letter of February 1^ had been satisfied.
Enclosed ic un improved copy of the paper for the tnmnoript. '
-------
UNIVERSITY OF CALIFORNIA, SANTA BARBARA
BERKELEY • DAVIS • IHVINE • LOS ANGELES • RIVERSIDE • SAN DIEGO • SAN FttANClSCO lrvjK,i J'-fiSsJ SANTA UAHIIAHA • SANTA. CHU7.
INSTITUTE OF ENVIRONMENTAL STRESS SANTA BARBARA, CALlfORNIA 93106
April 17, 1975
Dr. Herbert L. Wiser
Deputy Assistant Administrator
for Environmental Sciences
Office of Research and Development
U.S. Environmental Protection Agency
Washington, D.C. 20460
Dear Dr. Wiser:
Dr. Horvath has asked me to forward the enclosed
copy of his revised speech in accordance with the
request from your office.
Sincerely,
*t,- .
Nancy G. Robbins
Administrative Assistant
NGR:dc
Enclosure
-------
IN Htri v. Hnn-.«Ti)
DKPAHTMKNT Or» PA I HOUOOV
UNIVERSITY OF SOUTHERN CALIFORNIA
SCHOOL OF MEDICINE
2025 ZONAL AVENUE
LOS ANGELES. CALIFORNIA OOO33
I'nbnirtt'y
TELEPHONE
(213) 22B-1S1 I
Dr. Herbert L. Wiser
401 M Street - Room 919
Washington, D.C. 20460
Dear Herb:
Enclosed is the revised text. I believe it reads fairly well
now but in line with our telephone conversation I decided
not to do any major overhaul.* However, the changes made are
to me very important and I believe I have given the presenta-
tion significantly more impact, I hope.
At any rate, thank you for the opportunity of making these
changes. I would very much appreciate a copy, if this is
permissible, when my presentation is put together with the
others.
Needless to say, any comments or suggestions for improvement
would be welcome.
Sincerely,
RPS/dk
Enclosure
Russell P. Sherwin, M.D.
Hastings Professor of Pathology
01 kr
^ C- i^
-------
February 20, 197S
Honorable James G. Martin
House of Representatives
Washington, D. C. 20515
Dear Mr. Martin:
In response to your letter of February 5, 1975, regarding
my comments to the Charlotte Observer on the NOX standards, I
am enclosing a copy of a presentation I made during the Suspension
(of auto emission standards) Hearings held 1n Washington, D. C.,
In February 10-12, 1975.
The enclosed writeup covers fairly well-certainly more
analytically than the newspaper writeup—my viewpoint regarding
justification for and optimum degree of NOX control needed for
acceptable air quality. Other viewpoints and more details on
the Issue of the NOx standards were presented at the afore-
mentioned Suspension Hearings, a transcript of which can be
purchased from
ACE-FEDERAL Reporters, Inc.
415 2nd Street, N.E.
Washington, D. C. 20002
For an executive summary of these Hearings, may I suggest that
you address your request to Mr. Russell Train's Office through
EPA's Congressional Liaison office
Mr. Hugh Miller (A102)
801 West Tower
401 M Street, I.W.
Washington, D. C. 20460
or through
Dr. Herbert Wiser
Office of Environmental Sciences
RD-682
Washington. D. C. 20460
-------
We appreciate your Interest 1n the environmental Issues
and In our research efforts. If there Is any way M» can
assist you further, please, let us know.
Sincerely yours,
Basil Olmltrlades, Chief
Atmospheric Reactivity Section
Chemistry A Physics Laboratory
Enclosure
cc: Mr. Hugh Miller
9r. Herbert Wiser
-------
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
National Environmental Research Center
>,«,,i«lV" Research Triangle Park, North Carolina 27711
February 21, 1975
Mr. Harry Thron
Office of Environmental Sciences
RD-682
Washington, D. C. 20460
Dear Harry:
As you requested, I am enclosing here a copy of my
presentation at the Suspension Hearings - NOX Chemistry
and a set of hard copies of Dr. Altshuller's slides.
I apologize for the quality of some of Dr. Altshuller's
graphs. He has the originals with him out of town and I
did not want to wait till he comes back.
If you need anything else, please, let me know.
Sincerely yours,
Basil Dimitriades, Chief
Atmospheric Reactivity Section
Chemistry & Physics Laboratory
Enclosures
-------
OH lAMrnn MAHONIY
Vi( n r'liisKloiil Mrul Ini Iii 111 ill DIMI. loi
Reference: JRM-62
18 February 1975
Mr. Russell Train, Administrator
U. S. Environmental Protection Agency
401 M Street S.W.
Washington, I). C. 2(M(>()
Dear Mr. Train:
I am enclosing a written copy of the statement which I
presented on 11 February 1975 during the EPA Hearing on
NOX control.
Sincerely,
. „•"} V
James R. Mahoney
Vice President and
Technical Director
JRM:BQH
Enclosure
cc: Dr. Herbert L. Wiser
Dr. E. J. Bentz, Jr.
Dr. George M. Hidy
-------
WASHINGTON STATE UNIVERSITY
PULLMAN, WASHINGTON 99163
DEPARTMENT OF CIVIL AND ENVIRONMENTAL ENGINEERING
February 21 , 1975
Dr. Herbert Wiser
Deputy Assistant Administrator
for Environmental Sciences
Office of Research and Development
United States Environmental
Protection Agency
Washington, DC 20460
Dear Dr. Wiser:
The enclosed narrative accompanying the slides I discussed at the
Scientific Seminar on Automotive Pollutants, February 11, 1975, is
an attempt to recap my presentation. Enclosed are the figures from
which the slides were made. I hope that this material will help you
to compile the revised and complete transcript of my paper that you
have requested.
Reinhold A. Rasmussen
Professor
Environmental Engineering
Air Pollution Research
RARrbw
Enclosures
-------
SYSTEMS APPLICATIONS. INC. 415
950 NORTHGATE DR., SAN RAFAEL,, CALIFORNIA 94903
20 February 1975
Dr. Herbert I. Wiser
Deputy Assistant Administrator
for Environmental Sciences
U.S. Environmental Protection Agency
Washington, D.C. 20460
Dear Dr. Wiser:
My comments at the Scientific Seminar on Automotive Pollutants
(11 February 1975) were based largely on two papers: Hecht et al.
(1974) pp. 338-339 and Reynolds and Seinfeld (1975) (to be published
in Environmental Science and Technology). A reprint of the first
paper is enclosed; a preprint of the second paper is being sent to
you by Prof. Seinfeld.
Because of the short notices and deadlines for papers presented
at the recent seminar, I regret that I will not be able to prepare
a formal paper for inclusion in the record. In lieu of such a paper,
however, I am enclosing a brief summary of my talk, including the
figures shown during the presentation. Hopefully, this summary, in
combination with the papers mentioned above, will facilitate your
compilation of the transcript. Should you run into any difficulties
during the editing process, I will be glad to provide additional
help.
Sincerely,
Thomas A. Hecht
Senior Scientist
TAH:bd
OTHER OFFICES: NEW YORK • WASHINGTON, DO • PARIS
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Ford Motor Company 20000 Rotunda Drive
Dearborn, Michigan 48121
Mailing Address:
P.O. Box 2053
Dearborn, Michigan 48121
February 21, 1975
Dr. Herbert L. Wiser
Deputy Assistant Administrator
for Environmental Sciences
United States Environmental Protection Agency
Washington, D. C. 20460
Dear Dr. Wiser:
Enclosed are the copies of the two talks I gave, "Recent
Advances in Smog Chemistry" and "Prediction of Future Urban Carbon
Monoxide Concentrations", in 'response to your letter of February 14,
I thought I had given copies to you at the meeting, however, I will
send these extras to you in the event they were lost .
Sincerely yours,
Bernard Weinstock
Manager, Chemistry Department
Scientific Research Staff
BWrcp
Enclosure
-------
STATE- OF CALIFORNIA—RESOURCES AGENCY
EDMUND G. BROWN JR., Governor
AIR RESOURCES BOARD
1709 - 11 th STREET
SACRAMENTO 95814
February
1975
Mr. Herbert L. Wiser
Deputy Assistant Administrator
for Environmental Sciences
Office of Research & Development
U.S. Environmental Protection Agency
Washington, B.C. 20460
Dear Mr. Wiser:
Enclosed is the paper "Ambient Air Quality Trends in the South
Coast Air Basin" that I presented at the Scientific Seminar
on Automotive Pollutants in Washington on February 12, 1975.
Dr. Dimitriades has the slides that I presented at the meeting.
It is my understanding that he will provide you with the
enlarged images of the slides.
Sincerely,
'uohn R. Kinosian
Chief, Division of Technical Services
cc: Basil Dimitriades
-------
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
National Environmental Research Center
Research Triangle Park, North Carolina 27711
March 21, 1975
Mr. Harry Thron
Office of Environmental Sciences
RD-682
Washington, D. C. 20460
Dear Harry:
Enclosed, please, find a set of hard copies of Mr.
Kinosian's slides. Not too good copies but this was the
best we could do without replotting figures etc. from
scratch. Best regards.
Sincerely yours,
^-'V^, y
Basil Dimitriades, Chief
Atmospheric Reactivity Section
Chemistry & Physics Laboratory
Enclosures
-------
UNIVERSITY OF CALIFORNIA, LOS ANGELES
BERKELEY • DAVIS • IRVINE • LOS ANGELES • RIVERSIDE • SAN DIECO • SAN FRANCISCO
SANTA BARBARA • SANTA CRUZ
DEPARTMENT OK METEOROLOGY
LOS ANGELES, CALIFORNIA 9O024
February 24, 1975
Herbert L. Wiser
Deputy Assistant Administrator for
Environmental Sciences
Office of Research and Development
U.S. Environmental Protection Agency
Washington, D.C. 20460
Dear Dr. Wiser:
As requested in your letter of February 14, 1975 I am submitting
the enclosed copy of the paper which I presented at the recent "Scientific
Seminar on Automotive Pollutants".
Sincerely yours,
0 £V
\A feX^A^
Xfbmes G. Edir^T ^
JGEsI
(/
-------
TEXACO
PETROLEUM PRODUCTS
F.NVIRONMENTAL PROTECTION TEXACO me.
DEPARTMENT P. O. BOX 609
14 197*5 BEACON. NEW YORK 12608
Dr. Hasll IU*itriades
U.S. Environaentsl Protection Agency
Notional Environmental Research Center
Research Triangle Bark, I.e. 27711
Dear Basil:
Attached please find a copy of the presentation on auto-
motive nollutante which I presented to the EM Scientific Seminar
in Washington, B.C., on February 12. 3y copy of this letter to
Dr. H. L. Wiser, a copy of the presentation is also being wade
available for his records. Should any questions arise* please do
not hesitate to contact a*.
I thought the seminar was productive and that the pro-
ceedings will be helpful in resolving the issues involved ID the
setting of IOX automotive emission standards.
I look forward to seeing you again in the future.
Regards.
Sincerely,
Signed: Bruoe S. Bailey
BSB-JAH Bruce S. Bailey
CC: Br. Herbert L. Wiser
Attachment
-------
\
I UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
.^ WASHINGTON, D.C. 20460
February 13, 1975
OFFICE OF
RESEARCH AND DEVELOPMENT
Mr. Clarence M. Ditlow III
Public Interest Research Group
2000 P Street, N.W.
Suite 711
Washington, D.C. 20036
Dear Mr. Ditlow:
Thank you for your letter of February 12, 1975 offering a paper
on short-term NO levels in various cities. I regret that the
Wednesday session of the seminar ended before you had the opportunity
to present the paper. I appreciate the effort involved in accumulating
and condensing the N02 data from computer files.
Mr. Thron presented your paper to the staff group preparing a
summary of the Seminar for the Administrator immediately after you
gave us the two advance copies on Wednesday. Although your paper
does not appear in the transcripts prepared by Ace-Federal Reporters,
I will consider it part of the offical Seminar record.
Sincerely yours,
Herbert L. Wiser
Deputy Assistant Administrator
for Environmental Sciences
am ******* f ***
-------
PUBLIC INTEREST RESEARCH GROUP
2DDD P STREET. N. W.
SUITE 711
WASHINGTON. D. C. 2DD36
(2D2) B33-97DQ
February 12, 1975
Dr. Herbert L. Wiser
Deputy Assistant Administrator
for Environmental Sciences
Environmental Protection Agency
Washington, D. C. 20460
Dear Dr. Wiser:
In reliance on the published schedule of the Scientific
Seminar on Automotive Pollutants, I arrived at the
Department of Agriculture for the 1:00 p.m. session in
order to make the attached presentation. Much to my dismay
I discovered that you had run ahead of schedule in the
morning so that the afternoon session was held then.
Accordingly, I request that the attached paper be considered
as if presented at the Seminar. I am sure that you will
recall that I requested the opportunity to make a presentation
prior to February 3> 1975. The attached paper should prove
particularly relevant since it is the only information I
heard presented relating actual short-term NC>2 levels in
various cities where EPA has said there is no N0? problem
to the suggested short-term NOp "standards" of Dr. Shy. The
NC^ levels examined were obtained from EPA's National
Environmental Research Center.
To expedite matters, I presented copies of this paper to Mr.
Thron of your office immediately after discovering the
scheduled afternoon session had been canceled. Thank you
for your consideration.
Sincerely,
Clarence M. Ditlow III
Enclosure
-------
[TEXACO]
•IIIIIM't' I'M
I N\ ll<< >NMKNT \1 . I'H» ITKl'TION
DKI'AKTMI'INT
•i'K\ KCD INC
i •. o i to \ r>< M >
IIIO \COIN. NI'AV YOIIK
February 19, 1975
Dr. Herbert L. Wiser
Deputy Assistant Administrator for
Environmental Sciences
U.S. Environmental Protection Agency
Washington,, D. C. 20460
Dear Dr. Wiser:
Please refer to your letter to me of February 14, 1975,
regarding your request for a copy of the paper which I presented
to the EPA Scientific Seminar on Automotive Pollutants on February
12.
By now you should have received your copy of my letter
of February l4 to Dr. Basil Dimitriades which attached a copy of
the presentation which I made to the Seminar. Just in case this
went astray,, I am attaching another copy for your use.
I will appreciate receiving a copy of the revised and
complete transcript of the Seminar as soon as it becomes avail-
able.
Sincerely.,
Barley
BSB-JAH
Attachments
-------
UNIVERSITY OF SOUTHERN CALIFORNIA
SCHOOL OF MEDICINE
2O25 ZONAL AVENUE
LOS ANGELES, CALIFORNIA 9OO33
IN Rr PLY REI i n To
DEPARTMENT OF PATHOLOGY
February 21, 1975
TELEPHONE
(213 )
226-2444
Herbert L. Wiser
Deputy Assistant Administrator
for Environmental Sciences
Office of Research and Development
United States Environmental Protection Agency
Washington, D.C. 20460
Dear Dr. Wiser:
Thank you for your letter of 2/14. I was pleased to learn
that I will have an opportunity of revising my presentation.
It was prepared much too hastily and had to fall short of the
kind of presentation I desired. Also, my conflict with another
major commitment at the same time did not help. At any rate, I
am hoping to improve the text substantially and submit it to
you by the 26th. I would appreciate a telephone call to clarify
the deadline; if you wish to receive it by the 26th, it will be
necessary to send it by Air Courier at their overnight rate of
approximately $25.00.
I appreciated the effort made by Dr. Pitts to hand carry
the presentation to the meeting, and was hoping to hear from
him on his return concerning the details of the session that he
chaired. Interestingly enough, I first learned that my presenta
tion had been made through a post card requesting a copy of the
talk. Hopefully, the overall effect of the presentation was
positive and, in general, appropriate for the occasion.
Sincerely,
Russell P. Sherwin, M.D.
Hastings Professor of Pathology
RPS:eb
-------
OLD DOMINION
UNIVERSITY
department of Chemistry • 804-489-6421 • P.O. Box 6173 • Norfolk, Va. 23508
March k, 1975
Dr. Herbert L. Wiser
Deputy Assistant Administrator
for Environmental Sciences
United States Environmental Protection Agency
Washington, D.C. 20l|60
Dear Dr. Wiser:
I must apologize for not getting my muriuooript Cor l,ho ",'Jolont,I Ho fiominur
on Automobile Pollutants" to you by the date requested. It will- bo in
your office by Friday. I hope this has not been a serious inconvenience.
Sincerely,
Alan E. Bandy'
Associate Professor
ARB/b
-------
Bell Laboratories
600 Mountain Avenue
Murray Hill. New Jersey 07974
Phone (201)582-3000
March 12, 1975
Dr. Herbert L. Wiser
Deputy Assistant Administrator
for Environmental Sciences
United States Environmental
Protection Agency
Washington, D.C. 20460
Dear Dr. Wiser:
It was a privilege for us to participate in the
scientific seminar on Automotive Pollutants. We have
prepared the enclosed paper from the outlines of our
presentations; it thus represents accurately the infor-
mation contained in our remarks.
We will appreciate receiving a copy of the
complete transcript when it is available.
Sincerely,
Graedel
B. Kleiner
Enc.
Copy of "Chemical Kinetic and
Data Analytic Studies of the
Photochemistry of the Troposphere"
-------
iBattelle
( i ilumlni • I .ilini.itmic",
rtO'i Ktllf, AvriHH'
( ,>lll11l!>ll\ < ll'ld I i 'III
Mrplionc ((>!•(, J'l't II .1
Irirx 2 I-Vr>4
February 28, 1975
Mr. Herbert Wiser
Deputy Assistant Administrator for
Environmental Sciences
U.S. Environmental Protection Agency
Washington, D.C. 20460
Dear Mr. Wiser:
Enclosed please find a copy of my paper "Nonregulated Photochemical
Pollutants Derived from Nitrogen Oxides", presented at the Scientific
Seminar on Automotive Pollutants. A copy of my slide material is
also enclosed.
I believe the seminar was highly successful in disseminating the most
recent research findings on automotive pollutants and I appreciated
the opportunity to present the results of our studies. If I may be
of further assistance please let me know.
Sincerely,
Chester W. Spicer
Staff Chemist
Analytical and Physical
Chemistry Section
CWS:mec
Enclosures
-------
NAVAL RESEARCH LABORATORY
WASHINGTON, D.C. 20375
IN Kt-PLY RKFt W TO:
28 February 1975
Dr. H. L. Wiser
Deputy Assistant Administrator
for Environmental Sciences
Environmental Protection Agency
Washington, D.C. 20460
Dear Dr. Wiser:
I enjoyed participating in your seminar. The manuscript you
requested is enclosed.
A.—launders, wea
Instrumental Analysis Section
Physical Chemistry Branch
-------
OLD DOMINION
UNIVERSITY
department of Chemistry • 804-489-6421 • P.O. Box 6173 • Norfolk, Va 23508
March 13, 1975
Dr. Herbert A. Wiser
Deputy Assistant Administrator
Environmental Protection Agency
Washington, D.C. 2014.60
Dear Dr. Wiser:
Enclosed is the manuscript requested for the "Scientific Seminar on
Automotive Pollutants" held February 10-12.
Sincerely,
Alan R. Bandy
Associate Professor
-------
B. FEDERAL REGISTER NOTICE OF SEMINAR
-------
4034
NOTICES
listed in the interim policy of November
19, 1373.
Applications submitted under 2(a) or
2(b) of the interim policy will be proc-
essed to completion in accordance with
existing procedures. Applications sub-
mitted under 2(c) of the interim policy
cannot be made final until the 60 day
period has expired. If no claims are re-
ceived within the 60 day period, the 2(c)
application will be processed according
to normal procedure. However, if claims
are received within the 60 day period,
the applicants against whom the claims
are asserted will be advised of the alter-
natives available under the Act. No
claims will be accepted for possible EPA
adjudication which are received after
March 28, 1975.
Dated: January 20,1975.
" JOHN B. HITCH, Jr., ,
Director,
Registration Division.
APPLICATIONS RECEIVED (OPP-32000/177)
EPA Pile Symbol 8612-IN. B * G Co., PO Box
20372, Dallas TX 75220. B & O BGS 10
DUST INSECTICIDE. Active Ingredients:
Carbaryl (1-Naphthyl Methylcarbamate)
10%. Method of Support: Application, pro-
ceeds under 2(c) of interim policy.
EPA File Symbol 1324-T. Du-Rite Chem. Co.,
Inc., 3584 Bladensburg Rd., Brentwood MD
20722. TAHITIAN CONCENTRATED
SWIMMING POOL ALGAECIDE. Active
Ingredients: n-AUryl (60% C14, 30% C16,
5% C12, 5% CIS) dimethyl benyl am-
monium chlorides 5%; n-Alkyl (68% C12,
32% C14) dimethyl ethylbenzyl ammo-
nium chlorides 5%. Method of Support:
Application proceeds under 2(c) of Interim
policy.
EPA Pile Symbol 11694-UE. Dymon, Inc., PO
Box 6175, Kansas City KS 66106. X-IT
SPOT WEED KILLER. Active Ingredients:
Isooctylester of 2,4-dlchlorophenojryacetlc
acid 1.64%; Isooctylester of sllvex [2-
(2,4,5-trlchlorophenojry) ] 0.54%. Method
of Support: Application proceeds under
2(c) of interim policy.
EPA Reg. No. 2124-764. W. R. Grace & Co..
PO Box 277, Memphis TN 38101. WONDER
GRO X-IT 14-4-4. Active Ingredients: N-
butyl-N-ethyl-a,a^t,-trlfluoro - 2,6-dlnltro-
p-toluldlne 0.54%. Method of Support: Ap-
plication proceeds under 2(c) of interim
policy.
EPA Reg. No. 961-283. Lebanon Chem. Corp.,
PO Box 180. Lebanon PA 17042. GREEN
ViEW £VKH PREEN FOR EVERGREENS
AND AZALEAS. Active Ingredients,: Trt-
fluralln (a.a.a - trtfluoro-2-8-dlnltro-N,N-
dipropyl-6-toluldine) 0.74%. Method of
Support: Application proceeds under 2(c)
. . of interim policy.
EPA Reg. No. 818-75. Merck & Co.. Merck
Chem. Dlv., Rahway NJ 07065. PLOWABLE
MERTECT 340-F FUNGICIDE. Active In-
gredients: 2-(4-thiazolyl) -benzUnidazole
42.28%. Method of Support: Label amend-
ment 1 proceeds under 2(c); Label amend-
ment 2 proceeds under 2(b) of Interim
policy.
EPA Reg. No. 618-74. Merck & Co., Merck
Chem. Dlv., Rahway NJ 07065. MERTECT
360-WP FUNGICIDE. Active Ingredients:
2-(4-thiazolyl)benzimidazole 60%. Method
of Support: Application proceeds under
2(c) of Interim policy.
EPA PUe Symbol 9556-EN. Ortex Products
Inc., 580 Perry St., Newark NJ 07105 OR-
TEX CONCENTRATED COPPER ALGAE-
CIDE. Active Ingredients: Copper Sulphate
Pentahydrate 10%. Method of Support: Ap-
plication proceeds under 2(c) of Interim
policy.
EPA Reg. No. 99-104. Watkins Products, Inc.,
150 Liberty St., Wlnona MN 559«7. WAT-
KIMS GRAIN KEEP U. Active Ingredients:
Propiomc acid 99 6%. Method of Support:
Application proceeds under 2(a) of interim
policy.
EPA File Symbol 984-AA. Wfiitmoyer Lab.,
Inc., 19 N. Railroad St., Myerstown PA
17067. WHITMOTER DEAD SORE. Active
Ingredients: N-3-pyrldylmethyl N'-p-nl-
trophenyl urea 2%. Method of Support:
Application proceeds under 2(b) of interim
policy.
[PR Doo.75-2270 Piled l-24-75;8:45 ami
IFRL 320-51
ENERGY RELATED SUSPENSION
AUTHORITY
Report on Progress and Impact
Section 119(10(2) of the Clean Air
Act, as amended by the Energy Supply
and Environmental Coordination Act of
1974, directs the Administrator to publish
in the FEDERAL REGISTER at no less than
180 day intervals beginning January 1.
1975, certain reports and findings on the
Implementation of EPA's energy related
suspension authority under section 119
of the Act. Specifically, the Administra-
tor is directed to publish a concise sum-
mary of progress reports required to be
filed by any person or source owner or
operator to which the compliance date
extension provisions of subsection 119 (c)
apply. Such reports are to include in-
formation on the status of compliance
with requirements imposed by the Ad-
ministrator under subsection 119 (c). In
addition, the Administrator is directed
to publish up-to-date findings on the im-
pact of section 119 upon applicable State
implementation plans and upon ambient
air quality.
As of January 1, 1975, no applications
for compliance date extensions under
subsection 119 (c) had been received by
the Administrator and no such exten-
sions were granted. Therefore, no pro-
gress reports were required of or filed by
any person or source owner or operator
under subsection 119(c). In addition, no
temporary suspensions or postponements
under subsections 119(b) and 119(i) be-
came effective before January 1, 1975.
Section 119, therefore, had no impact on
applicable State implementation plans
or ambient air quality from the date of
its enactment on June 22, 1974, up to
January 1,1975.
Date: January 17,1975.
JOHN QTJARLES,
Acting Administrator.
[FRDoc.75-2272 Filed l-24-75;8:45 amj
[FRL 326-1]
SCIENTIFIC SEMINAR ON AUTOMOTIVE
POLLUTANTS
Seminar
Notice is hereby given that a scientific
seminar will be held at the Thomas Jef-
ferson Memorial Auditorium, U.S. De-
partment of Agriculture, South Building,
14th Street and Independence Avenue,
I
'.;<«
}C
'«
Washington, D.C.. on February 10, 11,
and, ii' necessary, February 12,1975, each
day at 9 a.m.
The purpose of the seminar is to con-
tinue to assemble the most recent, re-
search knowledge on the health effects
and atmospheric chemistry of air pollut-
ants from automobiles by offering the
scientific community and other inter-
ested persons the opportunity to present
information through this forum.
Representatives of industry, environ-
mental groups, government agencies,
universities and private research insti
tutions are invited to present and dis-
cuss research findings pertaining to the
subject. The principal concern of the
seminar will be NO, because of recently
developed information on this subject;
however, the presentation of any new
information related to CO, HC, or othn
automotive pollutants is also in order.
Presentations should address the folio* -
ing 'agenda items: (1) health effects
(experimental animal and human stud-
ies) ; and (2) atmospheric chemistry
of NO, including the relationship of
NO* to hydrocarbons and the formation
of photochemical oxidants.
The meeting will be open to the publ'c.
Persons wishing to submit a paper, at-
tend, or obtain further information
should contact Dr. Herbert L. Wiser, Dep-
uty Assistant Administrator for Environ-
mental Sciences, Office of Research and
Development (RD-682), Environmental.
Protection Agency, Washington, D.O.
20460. The telephone number ia (202)
755-0655.
Persons failing to notify EPA by Feb-
ruary 3, 1975 of their intent to give ar>
oral presentation at the seminar shall
not be entitled to give such a presenta-
tion except at the discretion of EPA. Such
persons are not precluded, however, from
submitting written statements for the
record.
WILSON- K. TALLSY,
Assistant Administrator far .,."
Research and Development.";
JANUARY 21,1975. .,
[PR Doc.75-2274 Piled l-24-75;8:45 anil *'
FEDERAL COMMUNICATIONS
COMMISSION
[Report No. 737] ^ j,
COMMON CARRIER SERVICES .'/t'ff \
INFORMATIONl ^Ci|.\l>
Domestic Public Radio Services ** '"'&y*
Applications Accepted for Filing -
JANUARY 20, 1975.4
Pursuant to §§ 1.227(b) (3) and 21.30jf:
(b) of the Commission's rules, an
*AU applications listed In the appendix gne^
subject to further consideration and terle»
and may be returned and/or dismissed 11 not' 'fa-
found to be In accordance with the Commis-, "
slon's Rules, regulations and other require;* :
ments. - "O"
»The above alternative cut-off rules appW-
to those applications listed In tne appendix
as having been accepted In Domestic Public
Land Mobile Radio, Rural Radio, Point-to-.
Point Microwave Radio and Local Television
Transmission Services (Part 21 of the Rules).
FEDERAL REGISTER, VOL. 40, NO. 18—MONDAY, JANUARY 27, 1975
-------
C. GM COMMENTS
-------
(iKNKRAL MOTORS CORPORATION
February 10, 1975
Dr. Herbert L. Wiser
Deputy Assistant Administrator for
Environmental Sciences
Office of Research and Development
Environmental Protection Agency
Washington, D. C. 20460
Dear Dr. Wiser:
General Motors Corporation submits the attached docu-
ments to become part of the record of the "Scientific Seminar
on Automotive Pollutants," held in Washington, D. C., February
10-12, 1975. The first two documents have not been published
before. The remaining documents are already a matter of public
record but are included because of their bearing on the issues
discussed at this seminar.
1) "Smog Chamber Simulation of the Los Angeles
Atmosphere," Jon M. Heuss, Environmental Science
Department, General Motors Research Laboratories.
2) "A Critique of the Conclusions Regarding NOx in
the National Academy of Sciences' Report to the
U. S. Senate Public Works Committee, 'The Relation-
ship of Emissions to Ambient Air Quality,'
September, 1975," Jon M. Heuss and William A.
Glasson, Environmental Science Department, General
Motors Research Laboratories.
3) "National Air Quality Standards for Automotive
Pollutants—A Critical Review," J. M. Heuss, G. J.
Nebel, and J. M. Colucci, Journal of the Air Pollu-
tion Control Association, 21, 535 (1971).
4) "A Further Response to EPA's Discussion of 'National
Air Quality Standards for Automotive Pollutants: A
Critical Review,'" J. M. Heuss, G. J. Nebel, and J. M.
Colucci, Fuels and Lubricants Department, General
Motors Research Laboratories.
General Motors Building 3044 West Grand Boulevard Detroit, Michigan 48202
-------
Dr. Herbert L. Wiser
February 10, 1975
Page 2
5) "Inhibition of Atmospheric Photooxidation of Hydro-
carbons by Nitric Oxide," William A. Glasson and
Charles S. Tuesday, Environmental Science and
Technology, 4_, 37 (1970) .
6) "Ambient Air Quality and Automotive Emission Control,"
Wayne A. Daniel and Jon M. Heuss, Journal of the Air
Pollution Control Association, 24, 849 (1974).
•i
7) "EPA and GM Calculations of Automotive NOx Emission
Standards," Part of General Motors Statement Sub-
mitted to Subcommittee on Public Health and Environment
of the House Committee on Interstate and Foreign
Commerce on Implementation of the Clean Air Act,
September 13, 1973.
C . S . Tuesday
Technical Director
GM Research Laboratories
CST/ss
Attachments (7)
-------
A Critique of the Conclusions Regarding NO in the
A
National Academy of Sciences' Report to the
U.S. Senate Public Works Committee
"The Relationship of Emissions to Ambient Air Quality11
September 1974
Jon M. Heuss
William A. Glasson
Environmental Science Department
General Motors Research Laboratories
Warren, Michigan 48090
Submitted to
Environmental Protection Agency
Scientific Seminar on Automotive Pollutants
February 10-12, 1975
Washington, D. C.
-------
-------
NO EMISSION STANDARD TO MEET THE NQ0 AIR QUALITY STANDARD
X • L
The National Academy of Sciences (NAS) in its August 1974 Report to
Congress concluded that the current statutory NO emission standard of
A
0.4 g/mile may be somewhat too stringent for meeting the N02 air quality
standard in Los Angeles. Although the NAS did not state to what degree
the NO emission standard should be relaxed, the calculations summarized
A
in Figure 6-3 of Volume III indicate that between 1 and 1.8 g/mile NO
A
would be sufficient, depending on the Los Angeles vehicle growth thru
1990. This is in essential agreement with GM's calculation of necessary
NO emission standards.
X
Even though the NAS report did not discuss the original basis for the
NO statutory standard, it is appropriate to recall that similar rollback
x 1
calculations were used by Barth in 1970 to calculate an NO emission
A
standard of 0.4 g/mile. The Barth calculations were used by Congress in
developing the rationale for the statutory emission standards. Since
Earth's calculations were made before the air quality standards were
set, Barth had to assume what the air quality standards might be. In
the case of N02, he assumed that 0.1 ppm for one hour might be the
standard. However, the standard was subsequently set at 0.05 ppm as an
annual average which is equivalent, according to the NAS report, to 0.35
ppm for one hour. Thus, the original Barth calculation, which was the
major rationale behind the statutory standard, was too stringent by a
factor of 3.5. The NAS calculations mentioned above confirm this conclusion.
«fc
THE ROLE OF NO IN PHOTOCHEMICAL SMOG
v IL~~"" ~"-—"- """" J{
The atmospheric role of the nitrogen oxides is quite complex because of
the participation of these oxides in the photochemical reactions involved
in the formation of smog. Since the nitrogen oxides are involved in photo-
chemical smog both as reactants and products, and as promoters and
inhibitors, the effects of changes in the atmospheric concentrations of
nitrogen oxides cannot be considered without considering the effects
these concentration changes have on photochemical smog.
1
-------
ABSTRACT
The August 1974 NAS Report to Congress concluded that the statutory NO
A
emission standard of 0.4 grams per mile could be relaxed somewhat and
the Federal P^ air quality standard would still be achieved. This
conclusion is in agreement with GM's calculation of necessary NO
A
emission standards.
However, the NAS considered the existing analyses relating NO emissions
A
to subsequent oxidant formation inadequate and concluded that the Federal
oxidant air quality standard might not be met everywhere if the statutory
NO emission standard were relaxed. The objective of this report is to
A
critically review the bases for this conclusion concerning NO emission
A
standards.
In reaching their conclusion, we believe the NAS ignored a large body of
evidence which indicates that stringent NO reduction will make the
A
oxidant standard more difficult to meet in many large cities. The NAS
conclusion results from a superficial analysis of existing information
together with a lack of information on the role of NO in oxidant forma-
A
tion downwind of major cities. This lack of knowledge is not sufficient
justification for keeping the statutory NO standard. The NAS report
A
offers no reason to believe that the statutory standard will provide the
optimal NO control to reduce oxidant.
A
-------
The NAS report recognized this, and concluded that the existing analyses
relating NO emissions to subsequent oxidant formation are inadequate.
A
It further concluded that it is not certain that the Federal oxidant
standard would be met in all large cities or locations downwind from
cities if the statutory NO standard was, relaxed. Finally, it concluded
X
that the determination of the optimal level of NO emission control
A
necessary to most effectively inhibit oxidant formation is a complicated
problem and requires further research.
The Summary Statement of the NAS report omitted this last conclusion and
added a qualifier to the previous one, so that it read . . . "It is not
certain that the oxidant standard would be met in all large cities or
locations downwind from cities if the NO standard was relaxed, unless
A
auxiliary local measures were taken." The executive summary dropped
this last qualifier, leaving the erroneous implication that keeping the statutory
NO emission standard would enable the oxidant standard to be met everywhere.
A
We agree that the determination of the optimal level of emission control
necessary to inhibit oxidant formation is a complicated problem. We
also agree that there is not absolute certainty that the oxidant standard
would be met everywhere if the statutory NO emission standard was
A
relaxed. However, we believe that there is a large body of evidence
which indicates that keeping the statutory NO emission standard will
X
make the oxidant standard more difficult to meet.
We recognize that this is a complex and controversial issue. However,
we believe that the preponderance of evidence supports our view. In
either case, there is no reason to believe that the statutory NO
xv
standard will provide for the optimal control of oxidant. Until the
optimal level is determined, we believe that the prudent course of
action is to control NO emissions sufficiently to meet the N0~ air
X c~
quality standard.
The balance of this report consists of a review of the evidence concerning
the role of NO in photochemical smog and a critique of the arguments
A
used and questions raised by the NAS Committee.
-------
CURRENT UNDERSTANDING OF SMOG FORMATION
Photochemical smog formation is the result of chemical reactions between
hydrocarbons and nitrogen oxides in air, in the presence of sunlight.
The chemical mechanism of smog formation is very complex as evidenced by
2
the fact that Calvert, in a recent review of this subject, considered
over 450 chemical reactions. In the atmosphere, this complex chemistry
interacts with transport and dispersion processes to determine the
concentration of pollutants in space and time. All these processes are
influenced by topography and meteorology. Predictions of the effects on
smog of changes in the atmospheric concentrations of hydrocarbons and
nitrogen oxides must largely depend, therefore, upon empirical results
from experimental systems that simulate the atmosphere. Since the
atmosphere itself is much too complex to be adequately reproduced by any
single model, the results from a number of experimental systems must be
considered.
It should be noted that these experimental systems have already been
accepted as reasonable simulations of the atmosphere. This is evidenced
by the fact that the results from these systems indicating that reduced
atmospheric concentrations of hydrocarbons would reduce photochemical
smog are the only basis for the California and Federal regulations
controlling automotive hydrocarbon emissions.
Control Strategies
3 4
Tuesday and Stephens have described the application of the experimental
evidence of smog formation to control strategies for achieving the
Federal air quality standards. They have pointed out simple reduction
of the major pollutants, hydrocarbons, and nitrogen oxides is not the
most expedient course for reducing atmospheric oxidant concentrations.
It is known from laboratory studies of smog formation that although
reduction of hydrocarbon emissions will reduce oxidant concentrations,
concurrent reductions in nitrogen oxides will partially offset the
effect of hydrocarbon reduction. This situation results from the so-
called photostationary state of nitrogen oxides and oxidant (mostly
ozone) obtained from the reactions
-------
k]
N02 + hv - : - -NO + 0 (1)
' k2
0 + 02 + M - - - - 03 + M (2)
k3
0 + NO - - - - N0 + 0 (3)
yielding the equation
(03) = (lyKg) (N02)/(NO) (4)
Thus, it is the ratio of N02 to NO and not the absolute value of oxides
of nitrogen which determines atmospheric ozone concentrations. The
presence of hydrocarbon leads to increased oxidant concentrations because
hydrocarbons enhance the oxidation of NO to N02. This enhancement
depends on both the amount and type of hydrocarbon present. Thus,
oxidant concentrations depend on the HC/NO ratio as well as the amount
A
and type of hydrocarbon present.
Equation (4) predicts that the oxidant yield will increase indefinitely
as the ratio (N02)/(NO) increases. However, this condition is not
realized because of physical and chemical processes which remove 0, and
The preponderance of expert opinion is in agreement with Tuesday and
4
Stephens that simple reduction of hydrocarbons and oxides of nitrogen
is hot the most evpedient way to reduce oxidant concentrations. For example:
a) EPA's Air Quality Criteria Document for Nitrogen Oxides states,6 "Only
one reduction program promises to accomplish this goal (attainment of
air quality standards for oxidant and N02), that is, a vigorous HC-
reduction program coupled with NO reductions designed to reduce N00
x c.
levels below the health-related criteria level."
b) Dr. A. P. Altshuller, an EPA expert in photochemical smog formation,
reported to an earlier NAS panel looking into this subject,7 "Concurrent
control of HC and NO is likely to be less effective than is HC control
A
alone in terms of meeting the oxidant standard."
-------
Q
c) The Los Angeles Air Pollution Control District has devised a
control strategy based on this idea. It consists of NO emission
X
control sufficient to attain the air quality standard for NOp and
HC emission control to bring the atmospheric ratio of (NO ) to (H(
A
to a value of 1.5-2.0 in order to reduce oxidant.
Q
d) A 1973 NAS critique of the automotive emission standards also
concluded that the stringent NO statutory standard was not needed
A
to control oxidant formation.
The 1974 NAS report, on the other hand, concluded that the optimal level
of NO to inhibit oxidant formation requires further research. While
X
equivocal on NO , the 1974 NAS report did support the preponderance of
A
expert opinion that stringent HC control is necessary to reduce oxidant.
The 1974 NAS conclusion on NO was predicated on the uncertainty of what
A
might happen downwind of major cities. Although there have been no
direct experimental simulations of the role of NO in such situations,
X
there is a body of information which can be applied to the question.
Altshuller et al. have found that the onset of oxidant formation and
attainment of maximum oxidant yield occur at HC/NO ratios that increase
/\
with decreasing hydrocarbon reactivity. This has been confirmed at
GMR. Since the atmospheric mix of hydrocarbons farther and farther
downwind is expected to become richer in the less reactive hydrocarbons,
the optimal HC/NO ratio for oxidant formation is expected to increase.
X
At a constant HC level, this means that less and less NO will still
10
make considerable ozone. Altshuller et al. have concluded that "The
results suggest that reduction of oxidant to low levels by means of
nitrogen oxide control could prove difficult to attain."
Role of Natural Emissions
The finding that light paraffins can react under certain conditions to
produce elevated ozone concentrations is very significant in light of
-------
the fact that certain areas of the U. S., notably Los Angeles, have HC
emissions largely paraffinic in nature, due to natural gas leakage and
petroleum seepage. These emissions provide a lower limit to the HC
level that can be ultimately attained and, if coupled with existing NO
/\
concentrations, would be sufficient to completely inhibit oxidant formation.
However, the question still remains as to what extent HC and NO control
X
would be necessary to attain the air quality standards for oxidant and
N02.
GMR Simulation of Los Angeles Smog
A recent study in the GMR Smog Chamber has addressed itself to this
question. A series of Smog Chamber experiments was conducted which
included the contribution of natural paraffins and simulated both present
Los Angeles concentrations and expected future concentrations. The
objective was to determine the degree of hydrocarbon and nitrogen oxide
emissions control necessary to meet the Federal air quality standards
for 03 and N02 in Los Angeles.
To simulate the hydrocarbons in present-day Los Angeles, a 10-hydrocarbon
mixture was made up based on detailed hydrocarbon analyses of Los Angeles
air. This mixture was separated into two fractions -- a fraction repre-
senting controllable hydrocarbons and a fraction consisting of light
paraffins, presumably from natural sources. This mixture was irradiated
at conditions representative of ozone-alert days in Los Angeles. Then
the effects of 50-, 80-, 90-, and 100-percent control of the controllable
hydrocarbon fractions were investigated together with varying degrees of
nitrogen oxide emission control.
The maximum 1-hour ozone concentrations in these experiments are shown
in Figure 1. Figure 1 confirms that ozone formation is a function of
both hydrocarbon and nitrogen oxide concentration and that higher NO
A
concentrations inhibit ozone formation under realistic atmospheric
conditions. With even 100 percent control of the controllable hydrocarbons
in Los Angeles, these experiments indicate ozone concentrations approaching
the Federal air quality standard. Since the location of the maximum in
-------
the curves shifts to lower NO concentrations as hydrocarbons are reduced,
/\
these experiments also predict that reducing ozone by nitrogen oxide
control will be difficult, if not impossible.
The results in Figure 1 indicate that hydrocarbon control is much more
efficient than NO control in reducing 0,. On the other hand, reductions
X O
in NO at a constant HC level increase 0, concentrations somewhat before
x -j
reducing them. These results also show that the maximum 03 concentration
is not very sensitive to NOV over a wide range of NO concentrations.
X X
In this set of experiments, the N02 dosage was essentially proportional
to the initial NO concentration. Since these mixtures simulated both
/\
the present-day concentrations and a wide range of possible future
concentrations, this study provides strong support for the assumption
that reductions in NO will result in approximately proportional reductions
X
in average N02 concentrations.
Summary
Thus, the results of our recent GMR studies concur with the preponderance
of experimental evidence that control of NO , while the way to decrease
/\
N0? concentrations, will not reduce oxidant concentrations.
We agree with the consensus of expert opinion that based on the available
evidence, the best control strategy is clearly to control HC to meet the
oxidant standard and control NO to meet the NO- standard.
/\ *••
BASIS FOR THE NAS CONCLUSION CONCERNING NOV
. —. —""n -- —- -- - - •"• l™ •' - - '- - l ' A
Contrary to the weight of evidence just offered, the NAS Committee on
the Relationship of Emissions to Ambient Air Quality has concluded that
it is not certain that the oxidant standard would be met everywhere if
the statutory NO emission standard were relaxed. However, the basis for
A
this conclusion is not entirely clear. The NAS report does not develop a
set of arguments which lead to the conclusion. In fact, no hard evidence
on this question one way or another is presented. The report does, however,
-------
present a number of facts, interpretations, and impressions which, when
taken together, lead to their conclusion. These are, 1) the knowledge
that NO inhibition involves slowing down reactions and delaying the
X
appearance of products, 2) the fact that oxidant trends in different parts
of the Los Angeles Basin have been different as present controls have
been instituted, 3) the impression that transport of oxidant and high
oxidant values in rural areas are recently emerging problems, and 4) the
lack of studies involving long-term irradiations or long-range transport.
The remainder of this section is a critique of the arguments used and
questions raised by the NAS Committee in presenting these factors.
NO Inhibition
We acknowledge that NO inhibition involves slowing down reactions and
/\
delaying the appearance of products. We believe that this is very
important since the chemical reactions in the atmosphere that produce
smog are relatively slow. Considerable time is required for smog forma-
tion. During this time, additional pollutants are being added to the
atmosphere, and the reacting pollutants are continually being dispersed.
Objectionable concentrations of oxidants (ozone), eye irritants, and
plant-damaging agents can only occur in the atmosphere when the time
available for the appropriate chemical reactions exceeds the time required
to form these concentrations. Thus, changes in the atmospheric concentra-
tions of HC and NO that speed up the chemical reactions resulting in
X
smog formation will also increase smog incidence.
Therefore, since time is important in the formation of smog, predictions
about the effects on smog of reduced atmospheric concentrations of
nitrogen oxides should certainly consider the effects of these reduced
concentrations on the rate of smog formation. Experimental models of
the atmosphere that only consider the maximum concentration of a smog
product formed regardless of the amount of time required to form this
concentration are incomplete since the amount of time available for smog
formation in the atmosphere is limited.
-------
Unfortunately, we do not know enough about the interaction between
emissions, chemistry, and transport processes in the atmosphere to know
how much irradiation time is involved in various transport situations
throughout the country. Until we have sufficient information to simulate
various transport situations, we will not know what the effect of changes
in NO emissions would be. Up until now, all the experimental simulations
A
have been concerned with the Los Angeles problem on the basis that Los
Angeles does experience the highest oxidant concentrations.
The question has also been raised that normal smog chamber irradiations
of 6 hours of noontime sunlight do not sufficiently simulate a total
day's irradiation. While the total irradiation available in a day is
equivalent to more like 8 or 9 hours of the peak value, it must be
remembered that the oxidant peaks in the downwind portions of the Los
Angeles Basin (Riverside and San Bernardino) between 2:00-3:00 p.m. on
the average. Thus, a 6-hour irradiation does simulate the amount of
irradiation available thru the time of peak oxidant concentration in
even the downwind portions of the Basin.
Oxidant Trends in the Los Angeles Basin
The NAS report notes that oxidant concentrations have been decreasing in
the coastal and central portions of the Los Angeles Basin but have not
decreased at the inland and downwind stations. This difference can be
attributed to two possible causes. One is that the growth in number of
sources in some areas of the Basin have been rapid enough to counteract
the effects of emission controls. The other is that increases in oxides
of nitrogen and decreases in hydrocarbons have delayed the photochemical
reactions so that the maximum oxidant concentrations now occur farther
eastward in the Basin. Evidence for the first of these possible explana-
tions, differences in patterns of growth, is given in the NAS report.
However, no evidence is offered to support the second explanation.
Unfortunately, in the Conclusions of the NAS report, only the second
explanation, increases in oxiues of nitrogen shifting the oxidant peak,
is listed as a possible cause.
-------
4
Stephens has also pointed out that either changes in chemistry or
growth patterns, or a combination of both, are likely causes for the
different trends in the Los Angeles Basin. We have looked into these
two possibilities and find evidence to support the growth-pattern theory,
but none to support the increase in NO theory.
A
Population trends support a different pattern of growth in different
parts of the Los Angeles Basin. Between 1960 and 1970, the population
of Los Angeles grew at 1.3 percent per year (noncompounded) while San
Bernardino, Riverside, and Orange Counties grew at 3.5, 4.8, and 9.9
12
percent, respectively. Furthermore, traffic volume trends support the
growth theory. The average daily traffic on the freeways ringing downtown
Los Angeles grew at about 1 percent per year between 1969 and 1973.
The average daily traffic on freeways out to Riverside and San Bernardino
13
grew at between 6 and 7 percent (noncompounded) between 1962 and 1972.
Obviously, a more detailed analysis would be necessary to estimate the
growth in emissions which influence different portions of the Basin.
B'jt a simple rollback calculation can be made based on the above informa-
tion to look at the differences in oxidant expected purely from different
growth factors. Such a calculation is shown in Figure 2, normalized to
the average maximum hourly oxidant concentrations measured in 1963.
Indeed, downtown Los Angeles would be predicted to show a downward trend
while oxidant in Riverside would increase somewhat in the late 1960's
before starting to turn downward in the early 1970's. This is close to
the trends actually observed.
If the theory about increasing NO delaying the reactions were true, one
/\
would expect to see this evidenced in the diurnal patterns at various
locations in the Los Angeles Basin. We have investigated the average
diurnal patterns of oxidant for July-September in downtown Los Angeles
and Azusa, between 1963 and 1973, and in Riverside between 1963 and 1971
(the latest data we had available). There are no significant changes in
the diurnal patterns over this time period except for increases or
decreases in the peaks. Oxidant starts to rise at about the same time
in the morning at each site. There is no evidence that the start of
10
-------
oxidant formation has been delayed in the past ten years. Similarly,
the time of oxidant maxima, while somewhat different between sites, has
also not shifted in the last ten years. The oxidant still peaks in
downtown Los Angeles between 12:00 and 1:00 p.m, in Azusa between 1:00
and 2:00 p.m., and in Riverside between 2:00 and 3:00 p.m. Thus, we see
no evidence for the theory about increased NO delaying the reactions,
A
and we do see evidence for the variable-pattern-of-growth theory.
It is somewhat surprising that the changes in HC and NO emissions have
X
not changed diurnal patterns. However, our recent Smog Chamber simula-
tion which includes natural paraffins does show that oxidant is less
sensitive to changes in NO than previous simulations had led us to
>\
believe. In addition, detailed atmospheric sampling by the GMR Atmospheric
Research Laboratory in West Covina, California in the fall of 1973,
showed that the hydrocarbon-NO mixtures were still very reactive. We
X
would expect, as time passes, that the institution of stringent HC control
would change the HC/NO ratio sufficiently so that a delay in the appearance
X
of oxidant would occur.
Nonurban Qxidant
The Conclusions of the NAS report concede that high oxidant concentra-
tions occurring in nonurban areas may be caused by transport of man-made
emissions from distant cities, downward transport of stratospheric
ozone, photochemical reaction of natural HC and NO emissions, or some
X
combination of these factors. We agree. There is evidence that all
these processes do occur. However, the body of the NAS report contains
the following statement, "The appearance of large concentrations of
ozone at nonurban sites in the U. S. in 1971-1973, coupled with an
indication of low ozone levels in 1963 and low contemporary ozone con-
centrations in nonurban Europe and Africa, strongly suggests that man-
produced NO is the primary cause of high nonurban ozone in the U. S."
A
Obviously, statements such as this had a large influence on the MAS
conclusion qualifying any relaxation of the statutory NO standard. We
X
can examine the basis for this statement to see if the conclusion drawn
is valid.
11
-------
The NAS report ties nonurban ozone to an increase in NO emissions over
A
the years because of their impression that high, nonurban concentrations
are a recent occurrence. There is no question that since the Federal
standard of 0.08 ppm was set, there have been a great number of measure-
ments of concentrations approaching and exceeding the Federal standard.
This is in large part because there are many more measurements being
made since there is now a standard which must be met. The NAS report's
argument that European and African locations have not shown high, nonurban
ozone only quotes the average concentrations of 0.022 ± 0.012 ppm. This
is misleading since it is the peak concentrations which count. The NAS
argument that 1963 nonurban ozone in the U. S. was not as high as in
the early 1970's comes from a study of ozonosonde observation over North
14
America. This study of vertical ozone distribution involved 835
balloon ascents at 12 locations over about a 2-year span. Each ascent
(1000 ft/min) measured the ozone near ground level during a couple of
minutes. Thus, at a given site, ground level ozone measurements are
available for a few minutes on each of about 35 days a year. Also, the
vast majority of these ascents were launched between 1100 and 1300
Greenwich Meridian Time. Thus, in the eastern U. S. they were launched
between 6:00 and 8:00 a.m. local time, and in the western U. S. between
3:00 and 5:00 a.m. local time. It is unclear how the NAS can rely on a
few such measurements taken mostly in the early morning to draw conclusions
about afternoon oxidant levels not to be exceeded more than once per
year. Lea has summarized the distribution of lower troposphere ozone
levels (below about 5 km) from reference 14 showing that about 14 percent
of the soundings had ozone maxima exceeding 0.05 ppm, and 0.7 percent
had ozone maxima exceeding 0.10 ppm. This is probably a good estimation
of the distribution of background ozone.
It is unfortunate that the NAS Committee looked no further than the one
ozonosonde study to determine whether high nonurban ozone concentrations
had been measured prior to 1971. If they had, they would have found
that as early as 1949, sampling in the deserts as far as 110 miles
downwind of Los Angeles had uncovered oxidant concentrations as high as
0.25 ppm. They would have also found that measurements in 1956 uncovered
12
-------
oxidant concentration about 0.1 ppm at many nonurban sites in California
as far away from large urban developments as Crescent City. The
authors of reference 17 concluded that some of these instances could be
traced to the transport of urban pollutants but that some could not.
Reports of the California air monitoring network indicate that moderate
oxidant concentrations have been present in the central valley as far
18
back as measurements are reported -- 1963. Furthermore, elevated
oxidant concentrations associated with tobacco weather fleck have been
19
reported in Ontario, Canada and the eastern U. S. since the 1950's.
It is unclear how long nonurban oxidant concentrations above 0.08 ppm
have existed. However, the lack of reports before some date should not
be construed as indicating it wasn't there earlier. Even methane wasn't
reported as a trace constituent of the atmosphere until 1948.
We are slowly building up a body of knowledge that indicates that all
three processes -- transport of urban pollutants, transport from the
stratosphere, and photochemical reactions of natural emissions — are
involved in determining the ozone concentrations in nonurban areas.
Only careful, detailed studies will enable us to understand the role of
each. Certainly, our present state of knowledge doesn't lead to the
conclusion that recent increases in NO emissions are responsible. Even
/^
if they were, there is no reason to believe that the 90 percent control
inherent in the statutory NO emission standard is necessary to keep
/\
oxidant levels near background.
Lack of Studies Involving Long-Term Irradiations
We agree that there is a paucity of information in this area. Most of
the early studies of smog were simulations of a general nature, aimed at
understanding the complex photochemical process or looking at the efficacy
of general control strategies. As more detailed measurements of pollutants
in Los Angeles became available, it became possible to simulate the
specific Los Angeles situation. This was done because this is the worst
location for smog. As detailed measurements of pollutant concentrations
in other cities, downwind areas, and rural areas become available, we
will be able to simulate these and determine the efficacy of various
13
-------
control strategies. Based on our present knowledge, it is quite possible
that the optimal level of NO may vary from place to place. Until a
J\
number of studies simulating smog in downwind areas are published, we
won't know what the role of NO is in these areas. However, our lack of
/\
knowledge is not a justification for keeping the statutory standard.
The NAS report offers no reason to believe that the statutory standard
is the optimal level of NO control.
/\
As developed earlier, there is a large body of information which indicates
that keeping the statutory NO standard will make it less likely to meet
J\
the oxidant standard in Los Angeles -- which is the present worst location.
It must be remembered that even if the NO statutory standard is relaxed
J\
somewhat, there will still be considerable NO control. This strategy,
X
when coupled with stringent HC control, should provide the best solution
for Los Angeles and considerably reduce the man-made portion of nonurban
oxidant.
14
-------
0,40
0.3!
0.30
U25
-SSL
o
0.20
,O
-g 0.15
iO.IO
0.05
0
o—
o 100% HC CONTROL
BASELINE
MIXTURE
50% HC CONTROL
80% HC CONTROL
90% HC CONT!
O-
0.1
0.2
0.3
0.4
0.5
0.6
!N!T!ALNOVCONC.( PPM
A
Figure 1. Maximum One-Hour Ozone Concentrations
Produced from Irradiation of Multicomponent
Hydrocarbpn-NO Mixtures.
A
15
-------
£ 0.20
o.
Q.
I i I
Q
O
O
1C
ID
X
UJ
O
0.10
0.05
OBS. PROJ.
RIVERSIDE o
LOS ANGELES •
0
1963 65 67 69 71
YEAR
73
75
Figure 2. Projected Oxidant at Riverside, California,
Assuming 6-7% Automotive Growth per Year and
Los Angeles Assuming 1% Automotive Growth per
Year Compared to Observed Concentrations.
16
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REFERENCES
1. Barth, D. S., "Federal Motor Vehicle Emission Goals for CO, HC, and
NO Based on Desired Air Quality Levels," J. APCA, 20, 579 (1970).
x
2. Demerjian, K. L., Kerr, J. A., and Calvert, J. G., "The Mechanism
of Photochemical Smog Formation," in Advances in Environmental
Science and Technology," Pitts, J. N., Jr. and Metcalf, R. L.
(eds.), Wiley, N. Y., 1974, p. 1.
3. Tuesday, C. S., "Nitrogen Oxides in the Atmosphere," Appendix A to
AMA Statement at March 4, 1969 HEW California Waiver Hearing, Los
Angeles, California.
4. Stephens, E. R., "Photochemical Formation of Oxidants," presented
at "Conference on Health Effects of Air Pollutants," National
Academy of Sciences, Washington, D. C., Oct. 3-5, 1973.
5. Glasson, W. A. and Tuesday, C. S., "Inhibition of Atmospheric
Photooxidation of Hydrocarbons by Nitric Oxide," Environ. Sci. Techno!.,
4, 37 (1970).
6. "Air Quality Criteria for Nitrogen Oxides," Environmental Protection
Agency, Air Pollution Control Office, Washington, D. C., Jan. 1971.
7. Altshuller, A. P., Summary of remarks presented to National Academy
of Sciences Panel on Atmospheric Chemistry, March 23, 1972.
8. "Los Angeles County Air Pollution Control District Views on the
Emission Control Strategy to Achieve the Oxidant Air Quality Standard,"
April 5, 1974.
9. "A Critique of the 1975-76 Federal Automobile Emission Standards
for Hydrocarbons and Oxides of Nitrogen," report of the Panel on
Emission Standards and the Panel on Atmospheric Chemistry for the
Committee on Motor Vehicle Emissions, National Academy of Sciences,
May 22, 1973.
-------
10. Altshuller, A. P., Kopczynski, S. L., Wilson,> I, Lonneman, W., and
Sutterfield, F. D., J. Air Pollut. Control Assoc.. 19, 787 (1969).
11. Heuss, J. M., "Smog Chamber Simulation of the Los Angeles
Atmosphere," presented at EPA Scientific Seminar on Automotive
Pollutants, Washington, D. C., February 12, 1975.
12. California Population 1971, Report of the Department of Finance of
the State of California, Sacramento, California, May 1972.
13. Average Daily Traffic on the State Highway System, Los Angeles Area
1962-1972, Los Angeles Enlargements 1969-1973, Dept. of Transportation,
State of California.
14. Hering, W. S. and Borden, T. R., Jr., "Ozonosonde Observations Over
North America," Vol. I. H_, and III. Air Force Cambridge Research
Laboratory, Report AFCRL-64-30 (Jan. 1964).
15. Lea, D. A., J. Applied Meteorology, 7_, 252 (1968).
16. Bartel, A. W. and Temple, J. W., Ind. Eng. Chem.. 44, 857 (1952).
17. Harrison, W. K., Jr. and Lodge, J. P., Jr.,
J. Air Pollut. Control Assoc., 8, 341 (1969).
18. Ten Year Summary of California Air Quality Data 1963-1972, Report
of the Air Resources Board, State of California, Jan. 1974.
19. Heggestad, H. E. and Middleton, J. T., Science, 1_2J9, 208 (1959).
18
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-------
NATIONAL AIR QUALITY STANDARDS
FOR AUTOMOTIVE POLLUTANTS -
A CRITICAL REVIEW
J. M. Heuss, G. J. Nebel and J. M. Colucci
Reprinted from
APCA Journal
Vol. 21, No. 9, September, 1971
Research Laboratories • General Motors Corporation
-------
-------
NATIONAL AIR QUALITY STANDARDS
FOR AUTOMOTIVE POLLUTANTS -
A CRITICAL REVIEW
J. M. Heuss, G. J. Nebel and J. M. Colucci
General Motors Research Laboratories
The recently promulgated national air quality standards
for carbon monoxide, nitrogen dioxide, hydrocarbons,
and photochemical oxidant are critically reviewed.
This review indicates that the standards are more re-
strictive than can be supported by available data.
Messrs Heuss, Nebel, and Colucci are associated with the
Fuels and Lubricants Department, General Motors Re-
search Laboratories, Warren, Mich. This paper was pre-
sented at the 64th Annual Meeting of the Air Pollution
Control Association at Atlantic City, June, 1971 as Paper
No. 71-37.
September 1971 Volume 21, No. 9
The carbon monoxide standard is based on a blood
carboxyhemoglobin level below that associated with
any physical or mental impairment.
The nitrogen dioxide standard is based upon a ques-
tionable epidemiological study that needs further
verification.
The hydrocarbon standard is orders of magnitude
below the levels associated with any health effects and
is unnecessary.
The photochemical oxidant standard is based on a
questionable extrapolation of the results of a single
study.
Based on all the available data, less restrictive standards
are suggested which would adequately protect the pub-
lic health and welfare.
535
Reprinted from APCA Journal, Vol. 21, No. 9, September, 1971
-------
The Federal Government recently issued national air quality
standards. These standards were established "...with an
adequate margin of safety..." and ".. .to protect the public
welfare from any known or anticipated adverse effects of a
pollutant."' Because of the economic and social consequences
of implementing these air quality standards, the studies
which formed the basis for the standards should be carefully
examined to determine the need and justification for the stan-
dards.
The required air quality can only be achieved by imple-
menting emission controls. The more restrictive the air quality
standards, the greater the degree of emission control required.
And, since the cost of emission control goes up exponentially
witli the degree of control, overly restrictive air quality stan-
dards will result in a totally unjustified economic penalty to
every citizen of the United States because there will be no
accompanying benefit in public health or welfare.
This paper will examine the air quality standards for four
automotive-related pollutants: carbon monoxide, nitrogen
dioxide, hydrocarbons, and photochemical oxidants. The
air quality standards and the analytical methods for determin-
ing compliance, as recently published in the Federal Register,1
are summarized in Table I. That document and the various
Air Quality Criteria documents2"6 are the basis for most of
the comments. Specifically, this paper will examine the
studies that formed the basis for the standards; review other
studies that were available with data and conclusions which
would have supported less stringent standards; explore the
interrelationships between hydrocarbons, nitrogen oxides,
and photochemical oxidants; and appraise the recommended
analytical techniques. Finally, air quality standards will be
proposed that will adequately protect public health and wel-
fare and yet not be overly restrictive.
Table I. National air quality standards for automotive-related
pollutants and the corresponding reference analytical methods.
Pollutant
Carbon
monoxide
Nonmethane
hydrocarbons
Nitrogen
dioxide
Photochemical
oxidant
Air quality
standard"
9 ppm for 8 hrb
35 ppm for 1 hrb
0.24 ppm C for 3 hrb
(6 to 9A.M.)
0.05 ppm — annual
arithmetic mean
0.08 ppm for 1 hrb
Reference method
Nondispersive infrared spec-
troscopy.
Total HC by flame ionization;
methane by gas chroma-
tography; nonmethane HC
by difference.
Jacobs-Hochheiser
Chemiluminescent spectros-
copy.
« Primary (health) and secondary (welfare) standards are equal for
these four pollutants.
b Maximum concentration, not to be exceeded more than once per
year.
Carbon Monoxide
The air quality standards for carbon monoxide ".. .are
intended to protect against the occurrence of carboxyhemo-
globin levels above 2 percent."1 These standards are heavily
based upon the studies of Beard and Werthe m,e which pre-
sumably showed impaired time-interval discrimination after
90 min exposure to 50 ppm carbon monoxide. The authors
recognized the many shortcomings of their own study. They
did not successfully measure the carboxyhemoglobin levels of
their subjects, and their studies were single-blind rather than
the preferred double-blind. In fact, Beard and Wertheim
concluded: "We do not suggest the immediate application of
these observations to the establishment of new air quality
standards or threshold limit values. Much remains to be
done before we understand the significance of performance
decrements associated with low concentrations of CO."
This reservation has also been espoused by the National
Academy of Science and the National Academy of Engineer-
ing.7 The concluding paragraph of the Introduction of their
report states "The report asks that aome critical experiments
be repeated to confirm existing findings and that other ex-
periments be initiated. Too rash or too rapid judgment
concerning the implications of these findings would be costly;
facts must be firmly established."
These warnings and the existence of data contrary to Beard
and Wertheirn's findings apparently were not recognized
when the EPA published the following in the Federal Register:
"The conclusions reached were that the evidence regarding
impaired time-interval discrimination had not been re-
futed ... ."1 Contrary to this statement, the studies by Stew-
art, et o/.,8»'8b Mikulka, et oZ> and Theodore, et aZ.,Sb do
refute the work of Beard and Wertheim.
Stewart's studies essentially repeated those of Beard and
Wertheim, but with better controls. The tests were double-
blind, carboxyhemoglobin levels were measured rather than
estimated, and the CO level in the exposure room was mea-
sured by three techniques. Stewart reported that the ability
of his subjects to estimate time intervals "w&snot impaired by
CO exposures, which resulted in COHb concentrations several-
fold higher than those which should have been encountered by
Beard and Wertheim." He also reported that, "The most
important finding was that an eight-hour exposure to 100 ppm
of CO, resulting in a COHb saturation of 11% to 13%, pro-
duced no impairment of performance in the tests studied
in this healthy group of volunteers."
A second independent study also arrived at the same con-
clusion. Mikulka, et al.,a" reported ".. .it may be concluded
that under conditions of this study, no effect of CO levels up
to 125 ppm and possibly as high as 250 ppm could be discerned
on time estimation."
Both of these studies were discussed at a September 9,1970
Conference on Environmental Toxicology.8b'9b Also at that
Conference, Dr. Beard reported that he repeated his original
study with a double-blind test procedure, and that this time he
was unable to find any decrement in time discrimination.
As stated earlier, the air quality standards for CO are in-
tended to protect against specific blood COHb levels. Carbon
monoxide from either of the two primary sources of exposure,
internal combustion engines or cigarettes, will raise the blood
COHb level. However, it is well recognized that COHb
levels in smokers are much higher than those in non-smokers
and are far above the 2% level upon which the air quality
standard is based. Therefore, meeting this air quality stan-
dard will not reduce the CO burden of that portion of the popu-
lation (smokers) which now experiences the highest COHb
levels.
Conclusions
In light of the above information, which was and still is
available to the EPA, it is surprising that the EPA concluded
that the original Beard and Wertheim study had not been
refuted. Since the air quality standard of 9 ppm CO for 8
hr was based in large part on the Beard and Wertheim study
which has been refuted, the present CO standard is too restric-
tive. The other studies cited in the Air Quality Criteria
Document for Carbon Monoxide2 indicate that there are no
effects of CO below COHb levels of 5% (which are frequently
exceeded by smokers). Applying an adequate margin of
safety to this suggests that COHb levels should not exceed
iy% to 3%. With this as a goal, the CO air quality standards
could realistically be established as: (a) 15 ppm for 12-hour
exposure. (6) 50 ppm for 1-hour exposure.
These standards offer adequate protection. The time
period for the first standard was increased from 8 to 12 hr, as
in the California State Air Quality Standard,10 to include both
the morning and evening traffic peaks. The second standard
will result in less than 2% to 3% COHb, but is included to
protect against short-term exposures.
536
Journal of the Air Pollution Control Association
-------
Table II. Relative response of NO in the
Jacobs-Hochhelser NOa method.
Test p»rts P«r million" * Relative NO
number Initial J-H NOi NO added Final J-H NO? response-%
1
2
3
4
0.038
0.105
0.209
0.474
0.08
0.50
0.10
0.50
0.01)1
0.1SO
0.238
0.659
16
9
29
37
" In air confined in a 300 ft3 chamber at GM Research Laboratories.
Note: NO; concentrations as measured by the continuous Griess-
Saltzman method did not change appreciably during the 4-hour
sampling period.
Nitrogen Dioxide
The nitrogen dioxide standard is based on a single epidemio-
logical study by Shy, et al.,"~18 conducted near a TNT plant
located just outside of Chattanooga, Tennessee. The "Chat-
tanooga Study" was designed to investigate the health effects
of exposure to NOs from a large stationary source—the TNT
plant. The concentrations of N02 and of other air pollutants
were measured at several sites during a 24-week period in 1968
and 1969. During this period, groups of school children
living near the sites were tested for ventilatory (breathing)
function, and their entire families were asked whether they
had any acute respiratory illnesses (colds, sore throats)
within the preceding two weeks. Later, a retrospective study
of acute lower respiratory infections (pneumonia, croup,
bronchitis) covering up to three years was conducted.
The major objections to the Chattanooga Study are the
measurement of N02 by the Jaoobs-llochheiser method and
tho interpretation of the medical results. Since the sig-
nificance of the medical results depend greatly on the mea-
sured N02 concentrations and since the Jaeobs-llochheiser
method has been prescribed by EPA as the reference method
for NO2, the method will be discussed in some detail before the
medicnl results are discussed.
Jacobs-Hochheiser Method
The main objection to the Jacobs-Hochheiser method is its
low and variable collection efficiency, which directly affects
the precision of the results. The N02 collection efficiency has
been studied by several investigators and appears to depend
greatly upon experimental conditions. Even when these
conditions are carefully controlled, the variations in efficiency
(and thus in precision) are appreciable. For example, Mor-
gan, Golden, and Tabor14 found the collection efficiency at
their recommended conditions to vary from 42 to 65% and to
average 53%. These same investigators also showed that
the porosity of the fritted bubbler and the liquid head above
the frit were important factors; both might be expected to
vary appreciably in a field study. Purdue, Dudley, Clements,
and Thompson" in a recent re investigation of the J-H method
found an average collection efficiency of 35% with a relative
standard deviation of about. 15%. Jacobs and Hochheiser"
reported N(Xi recoveries of slightly over 90%. Finally, Shy,
ft al.,[l determined an "empirical sampling factor" of 0.005
that WHH lined in their study. (This in tho HOIHO an the collec-
tion I'lliciency, annuming that the NOj-nitrito Htoichiometric
factor is 1.0 its recent work .serins to indicate."') Their em-
pirical sampling factor varied considerably with NO2 concen-
tration, but the authors do not show how great the variation
was at a fixed NO2 concentration.*
However, it is not likely that their collection efficiency
varied less than in the carefully controlled studies of Morgan,
Golden, and Tabor, and of Purdue, Dudley, Clements, and
Thompson.
A recent study by Christie, Lidzey, and Radford17 has
shown that the NOj collection efficiency can be raised from 34
to 95% by the addition of sodium arsenite to the absorbing
solution. It is difficult to understand why this modification
was not incorporated into the reference J-H method.l
Another objection to the J-H method is that it has an inter-
ference from NO. Some GMR test results showing this effect
are summarized in Table II. The relative response to NO
averaged about 25%. The three-fold discrepancy between
NASN and CAMP N02 data cited in the N02 Air Quality
Criteria document* may be partially explained by the NO
interference with the Jacobs-Hochheiser method.
All this casts doubt on the precision and accuracy of the NO2
measurements used by Shy, et al.,11 in their epidemiological
study. Certainly before the Jacobs-Hochheiser method can
be used to monitor atmospheric nitrogen dioxide reliably,
the collection efficiency must be improved, the interference
from nitric oxide must be eliminated, the precision must be
improved, and the discrepancy between the NASN and
CAMP NOz measurements must be resolved.
The Chattanooga Study
Because of the many deficiencies of the Jacobs-Hochheiser
method, the NO2 exposures reported in the Chattanooga
Study cannot be considered reliable. However, they are the
only numbers available upon which to judge the significance
of the medical findings in the three phases of this study, and so
will be used in the following analysis.
The locations of the various exposure areas are shown in
Figure 1; the concentrations of the air pollutants measured
are listed in Table III. School 3 in the High N02 area had
the same N02 exposure as the Control 1 area. School 3 is
* The coefficient of variation under controlled laboratory condi-
tions was later reported to be 8% (JAPCA, 20, 832 (1970)].
Table III. Arithmetic mean and 90th percentile concentrations of pollutants sampled for 24 hours at various sites (from reference 11).
N02, ppm
Suspended
Suspended
Pollutant
nitrate, Mg/m3
sulfate, jug/m3
Total suspended particulates, jug/m:i
Soiling index," Con/1000 lineal ft
Level of
exposure
Mean"
90 percentile11
Standard deviation
Mean
90 percentile
Standard deviation
Mean
90 percentile
Standard deviation
Mean
90 percentile
Standard deviation
Mean
90 percentile
Standard deviation
School
1
0.109
0.242
0.098
7.2
14.8
9.1
13.2
22.6
6.8
96
183
63
0.80
1.46
0.51
High NO?
School
2
0.078
0.141
0.054
6.3
13.4
5.8
11.4
19.2
6.4
83
138
46
0.89
1.73
0.64
School
3
0.062
0.098
0.040
3.8
8.0
4.6
10.0
19.5
4.9
63
108
42
0.91
1.84
0.68
High
partic-
ulate
0.055
0.087
0.024
2.4
4.6
1.7
10.7
17.3
4.6
99
181
58
2.09
4.37
1.67
Control
1
0.063
0.096
0.030
2.6
5.9
2.6
9.8
15.8
4.5
72
128
45
1.39
3.29
1.20
Contro
2
0.043
0.069
0.021
1.6
3.1
1.0
10.0
15.6
4.5
62
112
35
1.23
2.53
0.89
• Mean = arithmetic mean of all samples collected.
b 90 Percentile = concentration exceeded by only 10 percent of samples.
" 4-hour measurements.
September 1971 Volume 21, No. 9
537
-------
AREA
O SCHOOL
A SAMPLING SITE
Q TNT PLANT
Figure 1. Location of study areas, schools, and air sampling sites for
Chattanooga school children study (from reference 11).
ui i21
MALES
&
N02 F Cl C2 HO; F Cl Cl HO; P Cl C2 NOj P Cl CZ
AREAS
NOVEMBER 1961 8ARCH 1969 NOVEMBER 1961 MARCH IMS
Figure 2. Average FEVo 71 test results according to study area, month
of test, and sex of child (from reference 11).
Table IV. Analysis of variance effects on height-adjusted FEV0.7s of
sex of child, month of testing, and study area (from reference 11).
Probability of
Mean F significant
Factor square value difference
Sex of child 0.3852
Month of test 0.0318
Study area
High-NO2 vs. Controls 1 and 2 0.0098
High-TSP» vs. Controls 1 and 2 0.0011
Control 1 vs. Control 2 0.0004
189.3 p <0.01
15.6 p <0.01
4.8 p <0.05
0.6 not significant
0.2 not significant
1 Total suspended particulate matter.
located near the TNT plant (1.5 miles due west) a. id would be
expected to have a high NOj exposure. However, the lowest
NOj concentrations in the High KOj area were measured at
School 3. Moreover, there is a greater difference in exposure
among the schools in the High NOa area than there is between
the High NC>2 and Control areas. This raises even more
doubt about the accuracy of the NOj exposures.
Ventilatory Function. The results of the forced expiratory
volume (FEV) tests of second graders11 are given in Table IV
and in Figure 2. Shy, et. al., concluded that the difference
in FEVo.75 between the High NOj area and the control areas
(about 1%) was statistically significant. The real question
is whether it is medically significant. To determine this, one
must know the normal variation in FEVo.vj, which is reported
to be ±10%.18 Since the 1% difference in FEV0.7s between
the High NOa and Control area is less than the precision of the
spirometer test, much less than the difference between sexes
(even after adjusting for height), and less than the differences
between months of the year, its medical significance is ques-
tionable. A statistical test tells only whether two sets of
numbers are different; it does not tell whether the difference
has any physical significance.
Shy, et al., reported that there were no statistically sig-
nificant differences in FEVo.™ among the three schools within
the High NO2 area. Since the variation in NOj exposures
within that area was greater than the difference between the
High N(>2 and Control areas, it is difficult to conclude that
NOj adversely affected ventilatory performance. Moreover,
since the FEVo-vs results from the three schools within the
High N02 area were not separately reported, the dose-re-
sponse relationship between NOz and ventilatory function
could not be reliably judged.
Shy, et al., included School 3 in the High N02 area even
though the NOs exposure was identical to that in Control 1.
If School 3 had been included with the controls, the difference
in FEVo.76 between the exposure and control areas would have
been reduced and may not have been statistically significant.
Acute Respiratory Illness. The results of the second phase
of the study are reproduced in Table V.12 Shy, et al., com-
pared the illness rates in the three High N(>2 areas with the
two control areas and found an 18.8% relative excess in
respiratory illness in the High NO-2 areas for all family mem-
bers. A similar difference was found in each family segment.
However, School 3 and Control 1 had almost identical N02
exposures, but School 3 had a 17% greater frequency of res-
piratory illness that was also consistent among family seg-
ments. Moreover, Control 1, which had a higher NOz ex-
posure than Control 2, had less respiratory illness in all family
segments than Control 2. Since the illness rate does not
increase greatly with NOj within the High N02 area, and
since there is a 17% variability at a given N02 exposure level,
it is hard to agree with Shy, el al., when they conclude that,
"NO2 alone and exposure to suspended particulate alone ap-
peared to be the most probable explanation for the observed
excess in respiratory illness rates."
A more logical grouping of the study areas would be School
1 and School 2 as a high exposure area, School 3 and Control 1
as an intermediate area, and Control 2 as a low area. Under
these conditions, the interpretation of the respiratory illness
results would be quite different. There would be no difference
between the low and intermediate areas, and the difference
between the high and intermediate areas would be about the
same as the variation within the intermediate area. A logical
conclusion from this grouping of the study areas would be
that, if there is an NOz effect, it is only at exposures above those
in the intermediate area.
Lower Respiratory Illness. The third phase of the Chat-
tanooga Study was a retrospective survey of lower respiratory
illnesses in school children and infants residing in the study
areas used by Shy, et al. Parents were queried on the type,
' frequency, and severity of lower respiratory illnesses experi-
enced by their children during the past three years.
538
Journal of the Air Pollution Control Association
-------
Table V. Average biweekly respiratory illness rates per 100 for each family segment according to exposure
to oxides of nitrogen (from reference 12).
Rank of Population by NO: exposure
Average Average 24-hr
24-hr NOZ, suspended nitrate,
ppm ng/ma
0.109
0.078
0.062
0.063
0.043
7.2
6.3
3.8
2.6
1.6
Study
population
School 1
(high-NOO
School 2
(nigh-NO.)
School 3
(high-NO*)
Control 1
Control 2
All family
members
17.7
17.5
16.3
13.9
15.0
Family segment
Second
graders Siblings
23.4
23.4
20.4
18.0
20.1
19.9
18.0
19.1
15.6
17.0
Mothers
15.3
14.4
13.4
11.8
12.3
Fathers
11.0
12.8
12.1
8.8
9.6
Pearlman, Finklea, Creason, Shy, Young, and Horton13
reported an increased incidence of bronchitis among infants
exposed for three years and school children exposed for two
and three years. These results are shown in Table VI. How-
e.ver, Pearlman, el al., considered the Control 1 area of Shy,
<:t al., as an intermediate exposure area in making the statis-
tical comparisons. If Pearlman, et al., had made the same
comparison Shy, et al., had made (i.e., compare the High NOz
area with the Control areas), the differences in bronchitis
incidence would not have been statist'cally significant. Pearl-
man, et al,, generally found the highest illness rates in the
Control 1 area. It is difficult to conclude that NOz is causing
lower respiratory illnesses if intermediate exposures show the
highest illness rates. To judge reliably the medical sig-
nificance of these results, the dose-response relation between
NOz and illness rates must be examined. Since Shy, et al.,
measured a wide variation in NOz exposures within the High
NOi urea, the variation in illness rates within the High NOz
urea could be used to judge the significance of the results.
Unfortunately, this variation is not reported by Pearlman,
cl al.
The conclusions of the Chattanooga Study depend greatly
on the results from the Control 1 area. That area consistently
hud the lowest frequency of respiratory illness in phase 2 and
the highest frequency of bronchitis in phase 3. Since the
NOz exposure there was less than in the high NOz areas, it is
difficult to explain the medical results without concluding that
NOz can be beneficial as well as harmful. It is more likely
that other factors were responsible for the medical effects.
However, the authors avoid this complication by calling the
Control 1 area a low-exposure area when the illness rate is
low, and an intermediate area when the illness rate is high.
There is no justification for this dual classification.
In general, one looks at the dose-response relationship to
determine whether there is an effect due to a given stimulus.
If the response increases as the dose increases, one concludes
that there is an effect. If N02 is responsible for the differ-
ences noted by Shy, et al., one would expect that the effect
would increase as the NOz exposure increases. In fact, this is
not the case. There is a recurring conclusion in all three
phases of the Chattanooga Study that an effect threshold
may exist because exposures above an intermediate level
gave rise to no further impairment. It is extremely hard to
defend this interpretation if N0» is indeed responsible for the
effects noted.
Conclusions
Because of the many questions of interpretation and the
use of the ,1-11 method, the results of the Chattanooga Study
should not be the sole basis for setting a nitrogen dioxide
•standard. Additional epidemiological studies should be
carried out, ideally, around a large stationary N02 source
like the Chattanooga TNT plant. A more reliable N02
method than the Jacobs-Hochheiser should be used.
Until the findings of the Chattanooga Study can be vali-
dated by an independent study, the California Nitrogen
Dioxide Standard of 0.25 ppm for 1 hour is recommended.
Table VI. Distribution of children reporting one or more episodes of
bronchitis by length of exposure (from reference 13).
School children
6-month mean N02
High-N02,
156Mg/ms(0.083ppm)
Intermediate-N02,
118jug/m3(0.063ppm)
Low-NOz (control),
81 Mg/m1 (0.043 ppm)
exposure,
1 2
20.9 34.7-
31.6 45.5"
25.1 20.3
, yr
3
32. 2"
31.2"
23.2
Infant exposure,
1
33.3
26.2
21.1
yr
2
37.5
29.5
34.0
3
46.8"
50. 5"
36.3
1 Differs significantly from low-NC>2 (control) area.
This standard will minimize atmospheric discoloration and
provide more than adequate protection against any health
risk.
The continuous Griess-Saltzman method should be pre-
scribed as the reference method for nitrogen dioxide until
chemiluminescent NOz analyzers become available. The
Jacobs-Hochheiser method should not be used because of its
imprecision and interferences.
Hydrocarbons
Hydrocarbons are unique air pollutants. By themselves
they are harmless at present atmospheric levels,4 but they
can react to produce oxidant under certain meteorological
conditions. The hydrocarbon air quality standard is based
solely on the probability of nonmethane hydrocarbons react-
ing to produce oxidant. Since there is an oxidant air quality
standard, the hydrocarbon air quality standard is redundant.
The State of California recognized this and did not set a hy-
drocarbon air quality standard. This was wise because at
times of the year and at locations where conditions are not
favorable for oxidant formation, controlling hydrocarbons is
not necessary. In fact, it would be counter-productive be-
cause it would take emphasis and effort away from the control
of other pollutants.
Hydrocarbon-Oxidant Relation
Although an air quality standard for hydrocarbons is not
necessary, hydrocarbon emissions to the atmosphere must
be controlled in order to meet the oxidant air quality stan-
dard. To calculate the necessary emission reduction, the
complex relationships that exist in the atmosphere between
hydrocarbons and oxidant (and oxides of nitrogen) must be
known or assumed. The relationship or model used by EPA
to set the hydrocarbon standard is reproduced in Figure 3.
The hydrocarbon standard was derived from an extrapolation
of the upper limit hue of this plot of maximum daily oxidant
versus 6-9 A.M. average nonmethane hydrocarbon concentra-
tions that were measured in a number of U. S. cities. This
model is not satisfactory for reasons discussed below.
1. The model includes an excessively large probability factor,
that is, it relates a hydrocarbon concentration to a maxi-
mum oxidant potential which would be reached less than
1% of the time. At any location where the hydrocarbon
September 1971 Volume 21, No. 9
539
-------
LOS ANGELES^.-'* DENVER
WASHINGTON * , X" " ~
. "" * LOS ANGELES
."^ * PHILADELPHIA
" LOS ANGELES
PHILADELPHIA • X
ts
PHILADELPHIA »x
WASHINGTON f 4*
WASHINGTON/
u /
•• J: >"
6-9 o.m. AVERAGE NONMETHANE HYDROCARBON
CONCENTRATION, ppm C
Figure 3. Maximum daily oxidant as a function of early morning non-
methane hydrocarbons, 1966-1968 for CAMP stations; May through
October 1967 for Los Angeles (from reference 4).
standard is met, on only one day a year would the non-
methane hydrocarbon concentration exceed 0.24 ppm C.
On that day, the probability is only L% that the oxidant
standard would be exceeded. Thus, the combined prob-
ability of exceeding the oxidant standard is only once in
100 years. This seems unduly restrictive since the oxidant
standard as prescribed can be exceeded once a year. It
would be far better to derive a relation based on the com-
plete distribution of HC, NO*, and oxidant concentrations
at a given site, and then use this relation to determine
the hydrocarbon controls required to meet the oxidant
standard.
2. The present model does not take into account any changes
that might occur as emissions to the atmosphere are re-
duced. For example, the implementation of existing and
planned emission controls is expected to change the HC/
NO, ratio of the atmosphere substantially, and many
laboratory studies predict that this will also change the
oxidant-HC-NO* relation.19"21 In particular, ozone levels
are expected to increase when NO emissions are reduced.
The model should be able to take such factors into account.
3. The nonmethane hydrocarbon concentrations used to
derive the model are very imprecise. In fact, many of the
methane concentrations as reported are higher than the
corresponding total hydrocarbon concentrations—an ob-
viously impossible situation. At the Philadelphia CAMP
site, this occurred on 58 days during 1967. No nonmethane
concentrations were reported for those days (although
methane and total hydrocarbon concentrations were),
presumably because it would be difficult to explain negative
concentrations. One is led to wonder how many of the
other nonmethane hydrocarbon concentrations that went
into the model have just as large an error. It is evident
when one looks through all the data for the lowest non-
methane values that can be associated with a given oxidant
level, that many of them grossly underestimate the true con-
centration. For example, at the Philadelphia CAMP site
on Saturday, June 24, 1967, the 6- 9 A.M. average non-
methane hydrocarbon concentration was only 0.17 ppm
C, much less than one would expect in view of oxidant con-
centrations of 0.17 ppm that same day. However, be-
tween 3:00 and 6:00 A.M. the nonmethane HC concentra-
tion was —0.33 ppm C, which strongly indicates that the
reported 6-9 A.M. value was low. The data from this day
were not included in the model; but how many days were
included in which the error was just as large? This kind
of data probably defines the important upper limit line of
the model.
4. The model relies heavily on weekend data, which violates
some of its basic assumptions. Two basic assumptions
are that "early morning hydrocarbon levels measured at a
single point are proportional to the hydrocarbon levels
responsible for oxidant concentrations observed at the
same single point later in the day"4 and, that the 6 to 9
A.M. average is representative of early morning hydro-
carbon levels. If it is further assumed that daily emissions
are constant, these statements are generally true because
(1) there is an early morning traffic peak that accounts
for most of the hydrocarbons that react that day, and (2)
emissions are relatively constant from one day to the next
so that meteorological factors are responsible for day-to-
day differences in atmospheric concentrations. However,
many of the days used to determine the upper-limit line of the
model were weekend days, and thus are exceptions to the
general case since there are no early morning traffic peaks
on weekends. For example, detailed studies in several
cities have clearly shown that the weekend 6-9 A.M. hydro-
carbon emissions are only 5 to 10% of those on weekdays,
whereas the 9-12 A.M. emissions are about equal.22 Since
most of the hydrocarbon emissions on weekends occur after
9 A.M., the 6 to 9 A.M. average cannot be expected to char-
acterize the concentrations which react to form oxidant.
5. The model assumes that the atmosphere can become un-
stable as the morning proceeds but does not properly
account for the case where the atmosphere becomes more
stable. If the atmosphere does become more stable as
the morning proceeds, the hydrocarbon peak will occur
after 9 A.M. In this case, the 6-9 A.M. average is not in-
dicative of the hydrocarbon level responsible for the
oxidant level later in the day. An example will serve to
illustrate the point. Nonmethane hydrocarbon and oxi-
dant readings from the Philadelphia CAMP site for Tues-
day, July 18, 1967, are shown below:
Hour of Day
6-7
7-8
8-9
9-10
10-11
11-12
12-1
1-2
2-3
Non-methane
Hydrocarbon
0.6
1.0
1.5
2.3
1.2
1.4
0.8
0.6
0.6
Oxidant
0.02
0.04
0.10
0.16
0.13
0.13
0.14
0.13
0.12
The nonmethane hydrocarbon concentration averaged
1.0 ppm between 6 and 9 A.M., but increased to 2.3 ppm
between 9 and 10 A.M. when the oxidant concentration
was also greatest. This day, the 6 to 9 A.M. average was
not a good indication of the hydrocarbon reacting to pro-
duce oxidant.
6. The model does not adequately account for sampling loca-
tion factors which might affect the hydrocarbon-oxklant
relation derived from the air monitoring data. The model
540
Journal of the Air Pollution Control Association
-------
assumes that early morning hydrocarbon concentrations
at a point are proportional to the oxidant concentrations
measured at the same point later in the day. However,
the proportionality will vary from site to site. The
concentrations of primary pollutants, such as hydro-
carbons, oxides of nitrogen, or carbon monoxide, at a single
point depend greatly on local emission sources and the
proximity of the sampling site to these sources (for ex-
ample, auto traffic). Oxidant concentrations, on the other
hand, are representative of a much larger area since the
primary pollutants have had a number of hours to mix
and react. The HC-oxidant proportionality factor will
vary from site to site depending primarily on whether the
site is downwind of a major city (where oxidant is high and
HC is low) or located close to a major HC source.
7. The model was derived from only a fraction of the total
data available. CAMP data from only 1966-1968 and
data from only one year at one site in Los Angeles were
used. Unraveling the complex relationships between hydro-
carbons, oxides of nitrogen, and oxidant requires that all
the available data be carefully analyzed.
The hydrocarbon-oxidant relation used by Kl'A is un-
satisfactory for the reasons detailed above. The authors of
the Nitrogen Oxides Air Quality Criteria document also
expressed reservations about the model: "A model for pre-
dicting the upper limit of photochemical oxidant pollutants
from observed HC and NO* levels has been presented, but
needs further definition, sophistication, and revision before
it can be applied on a practical basis."4
Hydrocarbon Measurement Technique
Changing the reference method for nonmethane hydro-
carbons from a straight FID method to a combined FID-GC
method was a step in the right direction. (This instrument
also measures CO in the same sample. If it were specified
as the reference CO method, it would simplify the total instru-
mentation.) The old method was totally inappropriate for
determining whether the hydrocarbon standard was satisfied.
The new method may still not be sensitive enough, but it is the
best one available.
Background Hydrocarbon Concentrations
The hydrocarbon standard must be considered in relation
to background levels. Of the hydrocarbons which occur
naturally in the atmosphere, methane is by far the most
abundant. Worldwide measurements indicate a level of
1.0-1.5 ppm.58 Very little information is available on other
naturally occurring hydrocarbons. Concentrations of 0.003
ppm or less have been reported24 for ethane, ethylene, and
acetylene in rural, southern California, and 0.06 ppm of n-
butane has been reported25 in Pt. Barrow, Alaska. Terpene
hydrocarbons are given off by various types of vegetation.26
Atmospheric concentrations of a- and /3-pinene of 0.01 ppm27
and of isoprene of (0.0005-0.024) ppm28 have been reported.
Natural hydrocarbon sources include plants of various
types, decaying organic matter, coal and petroleum fields,
natural gas, and forest and grass fires. Thus, the natural
hydrocarbon background in a given area will depend upon the
particular plant life, petroleum deposits, etc., present in that
The most significant sources of nonmethane hydrocarbons
are the biological sources. How much they contribute to
the atmospheric hydrocarbon level in urban areas is not
known. However, the data that are available on terpeue
emissions and the fact that additional biological and other
miscellaneous sources are, as yet, unmeasured indicates that
the hydrocarbon air quality standard of 0.24 ppm C could be
exceeded by natural emissions alone.
Conctuslc .,
No hydrocarbon air quality standard is necessary since an
oxidant standard has been set. In order to meet the oxidant
air quality standard as quickly and efficiently as possible, a
relationship between hydrocarbon, oxides of nitrogen, and
oxidant is needed. The present model is, as shown above, not
adequate. Unfortunately, it has been used to develop the
hydrocarbon air quality standard. The EPA should derive
an appropriate relation from all of the data that it already has
and that it will collect in the near future.
The nonmethane hydrocarbon air quality standard if en-
forced will lead to a gross misdirection of control effort. In
locations where oxidant is not a problem, any effort to reduce
hydrocarbon emissions will be counter-productive. It will
produce no benefits to the public and it will take emphasis
away from the control of other pollutants.
Photochemical Oxidants
The oxidant standard is based on epidemiological studies
carried out in Los Angeles. Many studies on various aspects
of human health have been conducted there because
the population in parts of the Los Angeles Basin has been ex-
posed to oxidant concentrations as high as 0.6 ppm during the
past twenty years. The effects which have been associated
with the lowest oxidant concentrations are aggravation of •
asthma, impairment of athletic performance, and eye irrita-
tion.
The oxidant standard "is based on evidence of increased
frequency of asthma attacks in some asthmatic subjects on
days when estimated hourly average concentrations of photo-
chemical oxidant reached 0.10 ppm." This is based on a
study by Schoettlin and Landau29 relating asthma attacks to
oxidant pollution which showed an unspecified (but statis-
tically significant) increase in the number of mild attacks
which occurred when the peak oxidant concentrations ex-
ceeded 0.25 ppm. Six percent of the asthmatics participating
in this study were classified as "smog reactors." The Air
Quality Criteria Document for Oxidants associated this effect
with hourly average concentrations as low as 0.15 ppm by
applying the 99th perceutile of the relation between instan-
taneous and hourly average concentrations. This means that
at the 0.15 ppm level, there is a 1% chance of a small increase
in asthma attacks in a small percentage of asthmatics. How
this effect is associated with 0.10 ppm oxidant is unknown.
A study on athletic performance30 is weighted heavily in the
Air Quality Criteria Document for Oxidants. Based on the
assumption that cross-country running times tend to decrease
during the athletic season, Wayne, el al.,*° investigated the
percent of cross-country runners from a high school in Los
Angeles County whose running time failed to decrease from
meet to meet. This should be an extremely sensitive parame-
ter since long-distance races require maximum effort for an
extended period, and a runner's performance should be de-
pendent on his pulmonary function. The results of this study
are shown in Figure 4, where the percent of runners with de-
creased performance is plotted versus the oxidant concentra-
tion the hour before the race. Although an association with
oxidant level was shown, differences of a few percent in run-
ning time are all that are involved in even the worst case.
The Air Quality Criteria Document for Oxidants, as first pub-
lished, concluded that, "No threshold level for this effect can
be determined since the possibility always exists that a team
would always have a certain number of individuals who would
fail to improve their previous performance." However,
"errata" published for this document changed the conclusion
to, "A statistical test for threshold values (least squares analy-
sis) applied to these data shows that a significant threshold
level for this effect exists between 0.067 and 0.163 ppm." It
is difficult to understand how the conclusion could have
changed so drastically without any additional information.
If, rather than assuming that every runner must improve
September 1971 Volume 21, No. 9
541
-------
0.0 0.10 0.20 0.30
OXIDANT LEVEL 1-hour BEFORE MEET, ppm
Figure 4. Relationship between oxidant level
in the hour before an athletic event and per-
cent of team members with decreased per-
formance (from reference 30).
iii every race, one assumes that the probability of improving
one's previous performance is between 0.6 and 0.8, the "de-
creased performance" in Figure 4. should be between 20 and
40%. Based on this assumption, there is no effect below
0.15 ppm oxidant. This conclusion is supported by Koonitz,
who found no effect of oxidant in his study of the performance
of 115 men who ran two miles each week over a two-month
period in Seattle.31
According to the Los Angeles Air Pollution Control Dis-
trict,32 eye irritation is reported on as many as 60 to 70%
of the days during the smog season in areas of the Basin
where the oxidant concentrations arc highest. In winter,
when the peak oxidant concentrations are about 0.2 ppm,
eye irritation is reported on 0 to 3% of the days. Moreover,
the Los Angeles County Air Pollution Control District reports
that eye irritation is reported on an average of 171 days per
year (1959-1968 average) and that the 0.15 ppm oxidant
level is exceeded on an average of 222 days per year (1956-
1968 average). Although oxidant, per se, does not cause eye
irritation, the available data5 indicate that the threshold of
eye irritation can be associated with about 0.15 ppm oxidant.
The lowest reasonable estimate of the threshold is 0.1 ppm.
The Air Quality Criteria Document for Oxidant associated
lower hourly oxidant concentrations with eye irritation by
applying the 99th percentile of the relation between instan-
taneous oxidant and hourly averaged oxidant. It is improper
to use this relation to extrapolate to lower concentrations for
two reasons. First, it is improper to use instantaneous values
because the time to cause barely perceptible eye irritation at
threshold concentrations is an appreciable number of minutes.
Second, the 99th percentile should not be used because there
would then be only a 1% chance of experiencing eye irrita-
tion during the one hour a year that the oxidant standard is
exceeded. This would mean that, on the average, eye ir-
ritation would be experienced once in a hundred years. This
appears unduly restrictive.
This review of the studies of asthma, athletic performance,
and eye irritation shows that the threshold for the first effects
of oxidant pollution is 0.15 ppm. Other studies of the
health of Los Angeles residents are summarized below.
Studies of excess mortality,33'34 hospital admissions,35"38
and respiratory cancer39 in the general population and illness
rates, absence rates, and pulmonary function40 in school
children have not shown any correlation with photochemical
oxidants.
A study of chronic respiratory illness symptoms41 showed
slightly more cough, nose, and throat complaints in the Los
Angeles population than in the rest of the state, but more
reports of sinus and hay fever in the rest of the state than in
Los Angeles. However, when the "nine people who com-
plained of respiratory symptoms in this study were further
studied over a three-year period, no differences between Los
Angeles and outstate residents were found.42
A study of respiratory symptoms unil lung function in out-
door telephone workers in Los Angeles and San Francisco
showed significantly more reports of i-yo irritation in Los
Angeles and significantly more reports of chest illness in the
last three years in San Francisco.43 There were no differences
in lung function. Of the 37 symptoms queried (excluding
eye irritation), 19 were higher in Los Angeles and 18 were
higher in San Francisco. The frequency of respiratory symp-
toms increased with the age of the worker in Los Angeles but
decreased with age in San Francisco. This led to some differ-
ences between the two cities in the number of workers in the
50-59 year age group complaining of cough and phlegm.
However, this difference was found only among smokers.
Overall, there was remarkably little difference between Los
Angeles and San Francisco in the frequency of respiratory
symptoms even though oxidant concentrations were much
higher in Los Angeles.
Two studies have shown that subjects with chronic respira-
tory disease may experience some improvement in lung func-
tion when put in rooms with clean, filtered air.44'45 Two other
studies of persons with chronic respiratory disease have shown
that there is no association between respiratory symptoms or
respiratory function ami oxidant concentrations at present
Los Angeles pollution levels.46'47 Persons already having
chronic respiratory disease would be expected to be most
affected by high oxidant levels. However, no significant
effects have been shown below 0.15 ppm.
There have been many studies of the health of Los Angeles
residents and even though very few adverse effects have
been found, except for eye irritation, there is the general
belief that the day-in day-out exposure to high oxidant levels
for many years will cause chronic effects. Nobody can
prove or disprove this. However, long-term chronic effects
should be related to the average exposure. In this regard,
it is interesting that the average oxidant concentrations in
major cities (0.02 to 0.04 ppm) are very similar to those in
rural areas (0.01 to 0.03 ppm).5 This is because of the scaveng-
ing of ozone by nitric oxide. Since naturally formed ozone
has been present throughout history, and the oxidant ex-
posures in cities are close to natural levels, long-term chronic
health effects are not expected.
Background Ozone Concentrations
The photochemical oxidant standard must be considered
in relation to background levels; that is, the natural levels of
Os which exist in the absence of man-made sources. Mea-
surable 0.-) concentrations are found throughout the earth's
atmosphere, and the highest concentrations are found in the
stratosphere.48 The natural O3 level near the surface of the
earth depends primarily upon the amount mid type ot vegeta-
tion present and upon the weather. In general, the eurth'>
surface is considered to be a sink for Oa.48 However, it can
also be a source. Plants emit terpenes to the atmosphere211
which may react photochemically with nitrogen oxides (which
can also be of l)iological origin) to form O3.49 However,
terpenes also react directly with O3 to destroy it. Weather
can affect surface 03 concentrations because it affects local
mixing. Moreover, deep vertical mixing ahead of cold fronts
brings 03 from the upper atmosphere down to ground level
and increases surface Os concentrations substantially.4950
Thus, the concept of a true natural background Oj level is
rather nebulous. Since all of the processes described above
are "natural," a truly representative background 03 con-
542
Journal of the Air Pollution Control Association
-------
contention will only be representative for the area and the
time in which the measurements are taken.
Ozone concentrations have been measured in many remote
locations. Junge48 has surveyed tho, studies available through
U)oT> and has reported a mean value of 0.02 ppm.
The maximum values ranged from 0.025 to 0.00 ppm.
Ripperton, r,t al.,*" recently reported background Os concentra-
tions between 0.02 and 0.04 ppm. The Air Quality Criteria
Document for Oxidnnts, summarizing currently available
data, gives the range as 0.01 to 0.05 ppm with most of the
values between 0.01 and 0.03 ppm. In the extensive study
at Chalk River, Ontario (cited in the Air Quality Document),
the maximum Os concentration was 0.06 ppm and the mean
concentration was 0.01 ppm. The onset of a cold front can
increase these levels substantially. Vassy50 measured Os
concentrations as high as 1 ppm in the Alps, and Ripperlon51
measured 0.13 ppm in West Virginia under these conditions.
Thus, the air quality standard of 0.08 ppm could be exceeded
by natural processes.
Conclusions
A detailed analysis of the available information indicates
that there are no significant effects of oxidants on human
health at concentrations below 0.15 ppm. The Technical
Advisory Committee of the California Air Resources Board in
September 1970 concluded:10 "It has been stated that 0.10
ppm of oxidant is associated with eye irritation and with
possible impairment of pulmonary'function in persons with
chronic pulmonary disease. Review of the critical papers
quoted by the criteria document suggests that effects at the
0.10 ppm level are minimal and somewhat questionable. It
was also reported that background levels of oxidant arising
from natural sources in the absence of man-made air pollution
are occasionally as high as 0.05 ppm. It is the Committee's
opinion that 0.10 averaged over 1 hr represents a standard
which contains a reasonable safety factor." An oxidant
standard of 0.10 ppm for 1 hr would adequately protect the
public health.
In March 1971, the TAC reported further:52 "In sum-
mary, the proposed Federal standard is not supported by
available data on adverse effects, is not attainable within the
Federal time limit, and is so close to the natural background
as to be unreasonable."
Summary
A critical review of the studies which form the basis for the
national air quality standards for carbon monoxide, nitrogen
dioxide, hydrocarbons, and photochemical oxidants indicates
that the standards are unduly restrictive. The adverse effects
associated by EPA with these pollutant concentrations are not
substantiated by the data. Moreover, in setting the stan-
dards, EPA did not give proper attention to studies which
show no adverse effects at these concentrations and extrap-
olated the results of other studies of questionable validity.
This has resulted in air quality standards so restrictive that
they may be exceeded by natural processes alone. Based on
all of the available data, less restrictive standards are sug-
gested which would adequately protect the public health and
welfare.
References
General
1. Federal Register, 36, 8186 (1971).
2. Air Quality Criteria for Carbon Monoxide, National Air Pollu-
tion Control Administration Publication No. AP-62, March,
1970.
3. Air Quality Criteria for Nitrogen Oxides, Air Pollution Control
Office Publication No. AP-84, January, 1971.
4. Air Quality Criteria for Hydrocarbons, National Air Pollution
Control Administration Publication No. AP-64, March, 1970.
5. Air Quality Criteria for Photochemical Oxidants, National Air
Pollution Control Administration Publication No. AP-63,
Mureh, 1970.
Carbon Monoxide
6. Beard, It. It. and Wertheim, O. A., Amer. J. Public Health,
57, 2012 (1967).
7. "Effects of Chronic Exposure to Low Levels of Carbon Mon-
oxide on Human Health, Behavior, and Performance," report
of National Academy of Sciences and National Academy of
Engineering, Washington, D. C., 1969.
8. (a) Stewart, R. D., Peterson, J. E., Baretta, K. D., Bachand,
R. T., Hasko, M. J.. and Herrmann, A. A., Arch. Environ.
Health, 21, 154 (1970); and (b) Stewart, R. D., letter to En-
vironmental Protection Agency commenting on proposed
carbon monoxide air quality standards, March 5, 1971.
9. (a) Mikulka, P., O'Donnell, R., Heinig, P., and Theodore, J.,
Toxicol. Appl. Pharmacol. 18, 593 (1971); and (b) Theodore,
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Shy, C. M., Creason, J. P., Pearlman, M- E., McClain, K. E.,
Benson, F. B., and Young, M. M., J. Air Poll. Control Ass.,
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Shy, C. M., Creason, J. P., Pearlman, M. E., McClain, K. E.,
Benson, F. B., and Young, M. M., Ibid, 20, 582 (1970).
Pearlman, M. E., Finklea, J. F., Creason, J. P., Shy, C. M.,
Young, M. M., and Horton, R. J. M., Pediatrics, 47, 391
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Morgan, G. B., Golden, C., and Tabor, E. C., J. Air Poll.
Control Ass., 17, 300 (1967).
Purdue, L. J., Dudley, J. E., Clements, J. B., and Thompson,
R. J., Environ. Sci. TechnoL, in press.
Jacobs, M. B. and Hochhesier, S., Anal. Chem., 30, 426
(1958).
Christie, A. A., Lidx.ey, R. G., and Radford, I). W. F.,
Analyst, 95, 519 (1970).
Eckardt, R. E., J. Air Poll. Control Ass., 20, 832 (1970).
Hydrocarbons
Glasson, W. A. and Tuesday, C. S., Environ. Sci. Techno!., 4,
37 (1970).
Dimitriades, B., U. S. Bureau of Mines, Rept. Invest. 7433
(1970).
Altshuller, A. P., Kopczynski, S. L^, Wilson, D., Lonneman,
W., and
(1969).
W., and Sutterfield
Lopczynski,
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Air Poll. Control Ass., 19, 787
System Development Corporation Technical Memorandum
TM-(1)-4119, Volumes I through VI (1969).
Junge, C. E., "Air Chemistry and Radioactivity," Academic
Press, New York, 1963, p. 94.
Stephens, E. R. and Burleson, F. R., J. Air Poll.- Control Ass.,
19, 929 (1969).
Cavanagh, L. A., Schadt, C. F., and Robinson, E., Environ.
Sci. TechnoL, 3, 251 (1969).
Went, F. W., Tellus, 18, 549 (1966).
Rasmussen, R. A. and Went, F. W., Proc. Nat. Acad. Sci.
U. S., 53, 215 (1965).
Rasmussen, R. A., Environ. Sci. TechnoL, 4, 667 (1970).
Photochemical Oxidants
Schoettlin, C. E. and Landau, E., Public Health Rept., 76,
545 (1961).
Wayne, W. S., Wehrle, P. F. and Carroll, R. E., /. Amer.
Med. Ass., 199, 901 (1967).
Koonitz, C. H., as reported by Higgins, I. T. T. and McCar-
rol], J. R. in "Development of Air Quality Standards," A. At-
kisson and R. S. Gaines, eds., Merrill Publ. Co., Columbus,
Ohio, 1970, p. 90.
"Profile of Air Pollution in Los Angeles County," report pub-
lished by the Air Pollution Control District, Los Angeles
County, January, 1969.
Clean Air for California, California Dept. of Public Health,
Berkeley, Initial Report, March, 1955; Second Report,
March, 1956; Third Report, 1957.
Hechter, H. H. and Goldsmith, J. R., Amer. J. Med. Sci., 241,
581 (1961).
September 1971 Volume 21, No. 9
543
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35. Brant, J. W. A., Intern. J. Air Water Poll., 9, 219 (1963). 45.
36. Brant, J. W. A. arid Hill, S. It. G., Intern. J.Air Water Poll.,
8, 259 (1964).
37. Sterling, T. 1)., Phair, J. J., Pollack, S. V., Schunisky, D. A., 40.
and DeGroot., J., Arch. Environ. Umlth, 13, 1.18 (K)G(i).
38. Sterling, T. I)., Pollack, S. V., uiul Phaii-, J. J., An-h. Knviroii. 47.
Health., 15, 36'2 (1957). 4S.
39. IJuelJ, P., Dunn, J. 10., Jr., and Bivslow, I.., Ciimrr, 20, 2KW
(l%7). -19.
40. McMIIInn, l{. S., Wiseman, I). II., llano*, »., nml Wolirle,
P. I'1., Arrh. Knviron. llmltli, IS, 94 (I!M>9). .r,().
41. llausknoclit, H.. Air Pollution KIle.clM Reported by California .11.
Resident, Calif. Dopl. of Public Health, Berkeley, 19(1(1.
42. Hansknecht, K., Amir. AYw. H,:ii>inil. Din., 86, H.r>S (IWV2).
43. Deane, M., (ioldsmith, J. {{., and Tuina, I)., Arc.k. Knrirnn.
Health, 10, :i2:i (1965). f>2.
44. Motley, H. L., Smart, K. II., and Leftwich, (/. 1., ./. Amcr.
Med. Ass., 171, 1469 (1959).
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Pollution Control Association Meeting, Toronto, Outaiio,
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Hoka.v, S. N. and Alassev, F., Antci. Rev. Kesptrat. Dis., 86,
70ii (i%2).
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JiipptM-Uin. li. A , Kunifdirli, I. , mid Woi-l.li, ,). ,1 B , ./ ,lir
l'i,ll. ('outml AKH., 20, f.HII (197(1).
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|{i|ip«rl
-------
Discussion
Delbert S. Barth, J. Cyril Romanovsky, John H. Knelson,
Aubrey P. Altshuller, and Robert J. M. Morton
Office of Research and Monitoring, Environmental Protection Agency
Research Triangle Park, North Carolina
"Nothing would be done at all if a man waited till he could
do it so well that no one could find fault with it."
Cardinal Newman
The above quotation adorns the wall of the Office of Mr.
William D. Ruckelshaus, Administrator, Environmental
Protection Agency. The thought expressed is particularly
appropriate to the matter at hand, namely a discussion of the
paper by Messrs. Heuss, Nebel, and Colucci, which seeks to
challenge the recently published National Ambient Air
Quality Standards.
The criteria that provide the basis for the National Ambient
Air Quality Standards were developed through a series of
difficult and involved projects. Members of the National
Air Quality Criteria Advisory Committee were consulted
throughout the long, complicated, and tedious process. The
material was subjected to rigorous review by responsible
authorities both inside and outside of government. In
response to the proposed Standards, 390 comments were
carefully reviewed and considered. The Standards promul-
gated thus had input from many recognized experts from all
quarters. Clearly, it is manifestly impossible to satisfy
every reviewer in terms of responding completely to his
point of view. The point to be made here is that none of the
critical comments raised in the paper discussed below are
new to us. We had many difficult and lengthy sessions with
our Advisory Committee as well as within our own staff on
the very points raised. Ultimately, value judgments had
to be exercised, and decisions had to be made. Only time
and additional research data will prove to all concerned
whether our decisions, which are now a matter of record, were
the best possible decisions.
The basic premises advanced by the authors appear to be:
1. Many bits of information required to place the present
National Ambient Air Quality Standards on an irrefutable
and unassailable scientific basis are not yet available.
2. In view of (1) above, National Ambient Air Quality
Standards should be formulated in such a manner that they
do not impose undue economic burdens on industry and
on the consumer, who will ultimately have to absorb the
cost.
Item 1 cannot be contested; in fact, we agree with this
contention. We do, however, take strong issue with item 2.
National standards on such an important matter as air pollu-
tion must be established at levels that contain a sufficient
safety margin to provide reasonable certainty that all sensi-
tive population groups in the United States will be protected.
Economic factors must be secondary to thK primary con-
sideration. The Federal Government must align itself with
this admittedly biased position because the applicable law in
this matter is so clear that no other approach is possible.
In the following discussion, we, some of the Federal Govern-
ment employees charged with the responsibility of protecting
the health and Welfare of the citizenry, will explain why our
conclusions differ from those of the authors in many instances.
We will indicate some cases in which we agree with specific
points raised and have already taken steps to implement the
recommended actions. We will make reference to ongoing
research aimed at resolving some of the controversial matters.
Journal of the Air Pollution Control Association
544
-------
Carbon Monoxide
Introductory comments by Mr. Uuckelshausin establishing
the National Air Quality Standards do make special reference
to the objective evidence published by l)rs. Heard and Wer-
theim for decrement in human performance at very low levels
of carboxyhemoglobin.1 Lack of reference to other studies
of central nervous system or cardiovascular effects does not
imply, however, that such studies were disregarded. De-
terioration of vigilance,2 as well as of sensory, perceptual,
and cognitive functions,'•' have all been observed in persons
following exposure to low levels of carbon monoxide. Other
studies have failed to substantiate those observations.
Interestingly, Stewart, et al., using a select coterie of pro-
fessional subject.-*, have never demonstrated any decreased
performance in any tests they used at any level of CO ad-
ministered. One would suspect the tests were not very
sensitive. The comment that the work of Beard and Wer-
theim has been "refuted" is puzzling in the absence of any
published data showing the experimental procedure has, in
fact, ever been replicated. Although we are aware of un-
published data that confirm, as well as .some that fail to
substantiate, the original study of Beard and Wertheim, we
prefer to restrict, our di>cussion to published works.
Hecent research on cardiovascular effects not previously
called into evidence in support of the CO standard gives cause
for concern. Ayres, et al., have shown worrisome changes in
myoeardial metabolism and cardiac performance in humans
with as little as 7 per cent c.arboxyhemoglobin.5 Astrup,
et al., have shown a significant correlation between prolonged
exposure to low levels of CO and the development of athero-
sclerosis in humans as well as animals.6 Goldsmith and co-
workers have demonstrated a suggestive relationship between
ambient CO levels and case fatality rates from myoeardial
infarction,7'8 as well as death from other causes.9
Heuss, et al., quote Dr. Arthur DuBois, " . .some critical
experiments (must) be repeated to confirm existing findings...
Too rash or too rapid judgment concerning the implications
of these findings would be costly..."10 We agree whole-
heartedly with that statement, and our considerable invest-
ment in ongoing research on CO effects attests to this. Exist-
ing information on CO health effects has also compelled
Dr. DuBois to say, "We have to ask if there is any really
safe level of CO, If there were, one would look for a 'threshold,'
or level below which no adverse effects occurred. However,
three studies on neurological function have shown a response
to CO proportional to the CO concentration in the inspired air,
but proportional on upward from zero. These studies...
are those of Mills and Edwards on the carotid body, Mc-
Farland and co-workers on the retina, and Beard and Wer-
theim on discrimination of tone duration. It seems that CO
does not have a 'hockeystick' dose-response curve . We
should then rephrase... to ask: How much decrement in
function are we willing to tolerate under conditions of public
exposure for a specified time at a given concentration... ?" u
At this early stage of CO effects research, it should not
surprise any one that different experiments give contrasting
estimates of the minimal dose required to produce the earliest
demonstrable effect. No single study should be held up to
defend any point of view; when the body of available pub-
lished data on physiologic effects of CO in humans is examined
in its entirety, however, no responsible scientist or public
servant can argue for standards that are known to be asso-
ciated with health hazards for a large proportion of the popula-
tion. The question, then, is not, "What standard is con-
veniently attainable by industry?," but, "What price is the
consumer willing to pay for insurance against decrement
in neurological or cardiac function or insurance against pre-
mature death because of chronic exposure to CO?." We
believe he is willing to redirect some of his present investment
in transportation costs to provide that insurance, and, there-
fore, we cannot agree that the present CO standard is unduly
restrictive.
Nitrogen uioxlde
A unique opportunity to study the effects
-------
taking action on the basis of a "single" study. As is fre-
quently the rase, epidemiological studies are carried out as a
result of laboratory evidence of cause-effect relationships.
When an epidcmiological study can be shown to support
the laboratory findings, withholding control becomes the
more <|ucslionablc course of action, especially if the con-
sequences of judgmental error are only economic. Thcic are
ninny examples in medical history wherein a single study later
proved to be valid, and delay in its implementation resulted
only in needless suffering. The1 (-hattanooga Study was
undertaken in response to histological, biochemical, and
clinical laboratory studies implicating nitrogen dioxide MS a
possible potentiator of respiratory disease in man. The
epidemiological study in question supports that evidence.
lit the judgment of the Administrator the combined evidence
justifies the level of the Air Quality Standard.
Hydrocarbons
As presently utilized, the hydrocarbon standard is directly
associated with the implementation of the oxidant standard.
It is incorrect'to suggest that hydrocarbons do not directly
form carbon-containing products having adverse effects.
While it is true that the initial hydrocarbons, excepting
ethylene, have no known adverse effects, it is well known
that the organic products of hydrocarbons have the follow-
ing undesirable effects.
1. All of the known eye irritants, formaldehyde, acrolein,
pcroxyacyl nitrate, and peroxybenzoyl nitrate, can exist
only because of the presence of hydrocarbons as reactants.
2. Some aldehydes and peroxyacyl nitrates formed from
hydrocarbons cause plant damage.
3. Organic aerosols cause visibility reduction.
4. The organic peroxy compounds formed from hydrocarbons
are oxidants.
The main consideration in the existing standard is the well-
demonstrated ability to reduce oxidant concentration levels by
control of hydrocarbons. Control of oxidant necessitates lorm-
ulation of a hydrocarbon standard in a time interval that best
reflects its relationship to peak photochemical oxidant. Such
a formulation must be based on aerometric and laboratory
results showing that the air packet in which the oxidant is
formed has had a reasonable period of several hours of solar
irradiation between the time the hydrocarbons are emitted
and when peak oxidant is attained. Hydrocarbons emitted
later in the day have a significantly shorter period in which to
react; therefore, they contribute less to formation of un-
desirable products. In part, these effects are due to organic
reaction products of the hydrocarbons, and their elimination
requires the control of hydrocarbons in the atmosphere.
The oxidant standard could conceivably be achieved by the
elimination of all nitrogen oxides. Since, however, the
photochemical oxidant standard is to be achieved through
the control of the hydrocarbons that precede it, attaining
oxidant control is facilitated by a hydrocarbon standard
formulated in a time period that best reflects the relationship
of hydrocarbons to peak photochemical oxidants.
Hydrocarbon-Oxidant Relation
Simplicity in statistical reasoning is used to imply that the
combined probability of exceeding the oxidant standard is
only once in KM) years. This conclusion ignores the basic
realities of photochemical smog formation. The same me-
teorology that favors the formation of oxtdant favors the
accumulation of hydrocarbons during the time period of the
hydrocarbon standard. Critical smog incidents tend to
occur at a frequency in excess of 1% of the days in a year.
If on such days the hydrocarbon standard is not met, the
photochemical oxidant standard would not be expected to be
met. A hydrocarbon standard based on the complete dis-
tribution of all affected pollutants represents an ideal which
is predicated upon a complete understanding of all of the
September 1971 Volume 21, No. 9
related interactions. As the authors are well aware, validated
mathematical models of such complexity are not available
today. When such models are in use, the essentiality of a
hydrocarbon standard will be all the greater.
In principle, different control strategies for hydrocarbons
and NO, may conceivably result in temporary increases in
the ozone levels, but the effect in practice \\ill be small,
particularly in view of the benefits attending the prevention
of adverse N()2 concentrations. This question is addressed
in the Air Quality Criteria for Nitrogen Oxides,1'2 and a
model transcending our present knowledge would be required
to optimize a comprehensive control strategy Based on the
present model, an even higher degree of hydrocarbon control
would be required in order to prevent the "expected" in-
creases in ozone when NO emissions are reduced. Such
higher control may not be technologically feasible, and im-
plementing it to reflect the requirements of the model pre-
supposes a highly complicated motor vehicle emission control
strategy.
Much is made of the lack of precision attending the meth-
ane-free hydrocarbon data, but this weakness was recognized
in formulating the model relating methane-free hydrocarbons
to photochemical oxidants. Heuss, et al., cite data that they
admit were not employed in formulating the model to impugn
the very model itself when they conclude that "This kind of
data probably defines the important upper limit of the model."
A more reasonable conclusion might have been that these
kinds of data probably do not define the important upper
limit of the model, inasmuch as they were not included in the
model. Now that they are available, more precise analytical
tools for measuring the methane-free fraction have been
stipulated for all future measurements.
Weekend data tend to dominate the lower end of the upper
limit curve largely because of the reduced oxidant in the
areas under study on weekends. It is only on weekends that
low oxidant levels, approaching the value of the standard,
result during meteorologically favorable conditions in such
areas. (Because of reduced weekend traffic during the critical
period of the day, the hydrocarbons available for producing
oxidant were also low.) The fact that there may not be any
early morning traffic peaks on weekends does not modify the
basic reaction pattern relating primary pollutants, sunlight,
and photochemical oxidants.
The data presented by Heuss, et al., for July 18, 1967, from
the Philadelphia CAMP Station actually support the basic
premise of the hydrocarbon-oxidant model that it is the
hydrocarbons available for reaction during the 6- to 9-A.M.
period that are most directly responsible for the highest
oxidant levels during the day. Recognizing that there is a
time factor involved in the reaction of hydrocarbons with
nitrogen oxides to form oxidants, it should similarly be
recognized that the peak level from 9 to 10 A.M. is the result
of the hydrocarbons available prior to 9 A.M. If the 6- to 9-
A.M. hydrocarbon is not, "indicative of the hydrocarbon
level responsible for the oxidant level later in the day,"
the hydrocarbons later in the day are most assuredly not
responsible for the peak oxidant that occurred at 9 to 10
A.M. Furthermore, the July 18, 1967, hydrocarbon results
are not representative of most Sundays during 1967 in Phil-
adelphia. Such days are characterized by 6- to 9-A.M. hydro-
carbons that are equal to or greater than the 9-A.M. to 12-
noon concentrations.
The point is made that the hydrocarbon-oxidant propor-
tionality factor will vary from site to site and that the model
does not adequately account for sampling location factors
that might affect the hydrocarbon-oxidant relation derived
from the air-monitoring data. Such factors must be con-
sidered carefully before samplers are located for use in de-
veloping implementation plans for attaining the photo-
chemical oxidant standard. This should not disqualify the
model, however, inasmuch as sampling location variables of
importance were minimized at the sampling sites where the
546
-------
basic data were generated. The air-monitoring data used
were from renter city station*, which fan be expected to be
reasonably representative of the primary pollution several
distance-hours upwind on day of maximum atmospheric
stability.
The photochemical oxidant model is an empirical model
based on the best information available to us. The model is
subject to improvement, but the solution probably is not
through the vise of more of the same data with all of their
inherent weaknesses. Better data are required for the
development of a more comprehensive and sophisticated
model. Also data are needed from more places in order to
evaluate the universality of the model.
The hydrocarbon air quality standard of 0.24 ppm C could
conceivably be exceeded by natural emissions alone, but this
hypothesis has not been confirmed experimentally in any
urban area. The likelihood is remote that this situation
might occur in areas where the photochemical oxidant stan-
dard is exceeded and where an implementation plan would
have to be developed. Federal regulations stipulate that the
hydrocarbon standard is for use as a guide in devising imple-
mentation plans to achieve oxidant standards. Further-
more, KPA regulations for development of state implementa-
tion plans require that control of organic compounds from
stationary source emissions to reduce photochemical oxidant
formation also should be considered in areas where application
of the Federal motor vehicle emission standards will not
produce the emission reductions necessary. The regulations
also provide for adjustments reflecting the extent to which
occasional natural or accidental phenomena demonstrably
affected such ambient levels during the measurement period.
Photochemical Oxidants
We have re-examined the standard set for photochemical
oxidant pollution in relation to the comments made about it
and have come to the following conclusions: The standard
has been chosen on the basis of several good studies that
furnish data on the relation of oxidant level to eye irritation
and impaired athletic performance. The Richardson-
Middleton data18 on eye irritation are ample and present a
clearly visible threshold of effect at about 0.1 ppm of oxidant
exposure. Smaller amounts of data from two14'16 other rele-
vant studies reinforce this observation. Data from spon-
taneous reporting to regulatory agencies are subject to
numerous uncertain influences and are, therefore, not suitable
for use in determining dose-response relationships.
The time to cause barely perceptible eye irritation, based
on the laboratory method for measuring eye irritation, is 4
minutes. This is less than the integrated time response for
the potassium iodide oxidant analyzer results utilized. It is
appropriate, therefore, to use instantaneous (very short
time) values, in spite of the objections raised by the authors.
Furthermore, the standard was not specifically based on a
projection of the instantaneous value for eye irritation to
the associated hourly average. The primary standard does,
however, include a margin of safety applicable to all public
health effects, as required by law.
We have also reconsidered the data from the study on the
performance of cross-country runners of Wayne, et aZ.16
We have available not only the published study, but also
the data on which it was based, and similar data for a few
additional years. We do not, therefore, need to make
assumptions about these data. We observe, as we have
observed before, that decreased performance as com-
pared with the prior similar race is rarely observed except
in the presence of high oxidant levels. The higher the oxi-
dant levels, the more frequently it is observed. In their
comments pertaining to Wayne's study, Heuss, et al., make
several erroneous statements. It was not assumed that
every runner must improve in every race. The probability
of improving was estimated (using least squares) to be 0.87
rather (...,,! u t> to II. u^uie , ,«., i ,
statistical methods that dn not allow estimation of thresh-
olds in analyzing their d.-itn. \;>p!initii>ii ol u icclii,i<|ue
devised by \\~," \ cry similar to that reported bv Cjiiiiiidl '*
gives a (hi("-lidId <••-( iriiale
-------
4. Schulte, J. H., "Effects of mild iuiOui< monoxide u.m.vi •.-
Cum," Arch. Environ. Health 7: 524 0963).
5. Ayres, S. M., Mueller, H. S., Gregory, J. J., Oiannelli, S.,
Jr , and Penny, J. L., "Systemic and myocardial hemo-
dynamic responses to relatively small concentrations of
carlmxyhemoKlohin (COHb)," Arch. Environ Health 18:
<><)!> (I(HiO).
(i Aslmp, I', Kjcldscn, K., tirtd Wmisl nip, J, "KIIVcl* of
ciiilinii monoxide rx|M>Mir<* on mlcrml wiill*," Ann. A'.V.
\,-).
7 I inlilHinilli, .1 It and liiindini, H A , "('in)ion monoxide HIM!
hum.ill licidlli," .'n I'Hi: in.' I i ,? I I'H)H)
<< I 'nliiMi, M I, I'ltiiiin, \l , .'mil I iuM.iiiillli, J II, "1'iiilion
ninnniid"> nnd iiivoi'HMliid Infnii linn," \nti l''iii'i>nn llmllh
I'J . ">|D I |i>n ninnoxidp
Aswiiciiilion of coinnninilv nir pollnlioii willi moilnliU,"
.Snr'Mcr 172: 20.") (1971).
10. Kffrrts of chronic rjrpomirr to rrtrhon monoxitlf on human
health, behavior, anil performance. Arthur B. DnBois,
chairman, NAS, NAE, 2 p., 1969.
11. DuKnis, A. B., "Establishment of "threshold" carbon
monoxide exposure levels," Ann. A'.F. Acarl. Sei. 174: 42.">
(1070).
12. Air iiitaliti/ criteria for nitrogen oxiilrx, Knvironmental
Protection Agency, Air Pollution Control Office Publica-
tion No. AP-84, January 1971.
13. liichardson, N. A. and W. C. Middleton, "Evaluation of
filters for removing irritants from polluted air," University
of California, Department of Engineering, Los Angeles.
Keporl, Number 57-43. June I9.r>7.
14. Hammer, 1). I., el al. "Los Angeles pollution and respiratory
symptoms, Helationship during a selected 28-day period,"
Arch. Environ. Health 10: 47") (Mar 196.r>),
15. lien/ictti, N. A. and (iobran, V., "Studies of eye irritation
due to Los Angeles smog 1954-1956," Air Pollution Founda-
tion, San Marino. Calif., July 1957.
10. Wayne, W. S., Wherle, P. P., and Carroll K. K., "Oxidant
air pollution and athletic performance,' J. Amer. Med,
Assoc. 19!)(12):901 (March 20, 1967).
17. Hasselblad, V., Lowrimore, G., and Nelson, C. J., "Regres-
sion using 'hockey stick' function." Environmental Protec-
tion Agency. Unpublished Report.
18. Quandt, R. E., "The estimation of the parameters of a linear
regression system obeying two separate regimes," J. Amer.
Statistical Assoc. S3: 873 (1958).
19. National Aerometric Data Bank. Measurements from
Seattle, Washington, SAKOAD sites 49184002 and 49184013,
1968.
20. Koontz, C. H., as reported by I. T. T. Higgins and J. R.
McCarroll. In: Development of Air Quality Standards, A.
Atkisson and R. S. Gaines, eds., Merrill Publ. Co., Columbus,
Ohio, 1970, 90 pp.
21. Schoettlin, C. E. and Landau, E., "Air Pollution and asth-
matic attacks in the Los Angeles area," Public Health Reports.
76:545 (1961).
September 1971 Volume 21, No. 9 54g
-------
RESPONSE
National Air Quality Standards for Automotive Pollutants
Editor:
"Men are never so likely to settle a
question rightly as when they discuss
it freely" —Thomas Macaulay
This bit of wisdom applies as much
today as it did when penned over 100
years ago. Thus, we are disappointed
that Earth et al., in discussing our
paper, "National Air Quality Stan-
dards for Automotive Pollutants—A
Critical Review"1 did not explain why
our suggested standards are inadequate.
The lack of two-way communication
between EPA and the technical com-
munity on this important matter also
disappoints us. Many people have
sent, ninny comments to Washington,
but, EPA has never issued a public
statement, explaining in detail the basis
for the exact standards which wen-
chosen. To only state that the stan-
dards are based on published Criteria
Documents is inadequate.
We agree that economic factors must
lie secondary to the protection of pub-
lic health, but the question is "how
much protection?" Three of our four
suggested standards are identical with
California Standards,2 which were also
set, by officials charged with protecting
public health. They reviewed the same
information as EPA, but set different
standards, some more and some less
stringent.
The levels at which air quality stan-
dards are set are of great importance
because they form the foundation of
our national air pollution control effort.
If they are not chosen wisely, much of
the massive effort to meet the stan-
dards will go for nought. Therefore,
the standards deserve continuing scru-
tiny by both the general public and
the technical community.
Carbon Monoxide
There is no question that CO, or
other pollutants, have deleterious ef-
fects. The question is at what ex-
posures do these effects first appear.
Our suggested CO standard, 15 ppm
for 12 hours, is equivalent to a maxi-
mum COHb level of 2y2-3%3 The
annual average CO concentration as-
sociated with our standard (4.5 ppm)4
would result in an annual average
COHb level of 0.7% above the endog-
enous level.3
Except for the controversial Beard
and Wertheim study, none of the pub-
lished studies cited by Earth, et al., in
support of the national air quality
standards, show effects at 2.5% COHb.
For instance, they state "Ayres, et al.,
have shown worrisome changes m myo-
cardial metabolism and cardiac per-
formance in humans with as little as 7
percent carboxyhemoglobin." This
COHb level is about 2y2 times higher
than the one associated with our CO
standard. We are unable to comment
on the Horvath, et al., study since it,
is unpublished.
Earth, et al., state ". . . although we
are aware of unpublished data that
confirm, as well as some that fail to
substantiate, the original study of
Heard it Werthcim, we prefer to re-
strict, our discussion to published
works." (liven the limited informa-
tion available on effects at these ex-
posure levels, \ve would hope that, all
pertinent data would not only bo care-
fully reviewed, but, be made publicly
available. As recently pointed out by
Sterling,5 "Data on which scientific
claims are based must be public in the
sense that they are available for re-
view."
Barth, et al., criticize Stewart's selec-
tion of subjects and tests and claim that
his subjects, ". . . have never demon-
strated any decreased performance in
any tests they used at any level of CO
administered." We question whether
Barth, et al., have carefully read Dr.
Stewart's papers since his subjects
were chosen in a manner similar to
those of Beard and Wertheim and have
experienced effects, although only at
exposures above those at which Beard
reported effects. Moreover, Dr.
Stewart's tests have been described
by O'Donnell as, "... at least as sensi-
tive as those used by Schulte and by the
Beard group . . ."
O'Donnell6 recently discussed his at-
tempts to confirm the Beard and Wert-
heim study. He concluded "We wish
to emphasize that earlier results indi-
cating behavioral toxicity of CO act-
ing alone at, these levels have not
been confirmed. Obviously we still
must be concerned with the level of CO
in the environment. However, a great
deal of time and experimental effort
has now been devoted to what was
essentially a false alarm." Until data
confirming Beard and Wertheim are
made public and are accepted by the
technical community, we can only con-
tinue to conclude that the work of
Beard and Wertheim has been refuted
It is interesting that Dr. Beard's sub-
committee of the Technical Advisory
Committee of the California Air Re-
sources Board concluded that the na-
tional air quality standard of 9 ppm
>• nr avera^i- ... is I,,M
acceptable because it is more stringent
than supported by the data. . ."7
Nitrogen Dioxide
Barth, ft al., admit that there are
deficiencies in the Jucobs-IIochlieiser
method I'or NOo as used in the Chat-
tanooga Study. They state that, before
changes are made, any new method
must be compared with the J-II pro-
cedure as specified in the Federal Reg-
ister. However, we are still skeptical
of the J-H method and data obtained
with it, and question whether or not
the N02 results of the Chattanooga
Study can ever be unraveled.
As we have pointed out, the medical
results of the Chattanooga Study are
indeterminate—the\ can be used to
support, an effect or not depending on
how one looks at the data. Rather
than take the attitude that ". . . the-
consequences of judgmental error arc-
only economic; . . .," we believe the pub-
lic's investment of billions of dollar-
deserves a sounder basis than an inde-
terminate medical study conducted
with an indeterminate analytical tech-
nique.
Hydrocarbons
Barth, et al., state "It is incorrect to
suggest that hydrocarbons do not di-
rectly form, carbon-containing products
having adverse effects." We did not
suggest that, but we did suggest that
hydrocarbons be controlled to whatever
extent necessary to meet the oxidant
standard. It is encouraging that EPA
now agrees with this for in August
1971 they stated "It may be assumed
that the degree of total hydrocarbon
emission reduction necessary for at-
tainment and maintenance of the na-
tional standard for photochemical oxi-
dant will also be adequate for attain-
ment of the national standard for
hydrocarbons."8
Barth et al., present a lengthy de-
fense of their hydrocarbon-oxidant re-
lation. There is no point in further
discussion of this relation since it is
no longer being used by EPA. Their
new hydrocarbon-oxidant relation is
the solitary figure which is Appendix
.1 of Reference 8. Although referenced
to the No.,; Air Quality Criteria Docu-
ment, neither the figure nor its deriva-
tion appear in that document. Be-
cause of its critical importance EPA
should make public the derivation of
this new relation for review by the
technical community.
Photochemical Oxidants
Barth, et al., specify three studies
which act as the basis for the O.OS
ppm for one hour photochemical oxi-
dant s standard.
1. The Richardson-Middleton study9
showed that eye irritation starts to m-
788
Journal of the Air Pollution Control Association
-------
crease above background as concen-
trations exceed 0.1 ppm. Since the
oxidant concentrations they reported
were 30 minute bubbler samples, rather
than peak readings from a continuous
analyzer (as Barth, ct al, state), our
suggested Mandard of 0.10 ppm maxi-
nuini 1-hr average insures that eye
irritation will not he experienced.
2 In discussing the Wayne, ct al.,
study on athletic performance, liarth,
i'l al, explain how they used un/>ub-
linlicd data, together with an unpub-
lislird analysis to derive a threshold
\\lnrh, we would ]>oint out, is above
our suggested standard.
H. Barlli ct al., rely heavily on the
Schoetllin and Landau paper on asth-
matics in deriving the photochemical
oxidant standard. However, this study
has two major weaknesses. First, it
contains HO data, so neither the medical
significance nor the magnitude of 'the
effects reported can be estimated. Sec-
ond, no technique or averaging time is
specified for the oxidant measurements
obtained from the LA APCD. EPA
must have analyzed the unpublished
Schoetthn and Landau data many
times because they have arrived at
four different conclusions from this
work—none of which can be found in
the original paper, (a) When pub-
lished in March 1970, the Oxidant Cri-
teria Document concluded that there
was an effect at "hourly average con-
centrations ranging from 0.05 to 0.00
ppm," (6) Errata published for this
the conclusion to "hourly average con-
centrations as low as 0.15 ppm"; (c)
When the national standard was pub-
lished in April 1971, the conclusion be-
came "when estimated hourly average
concentrations reached 0.10 ppm"; (d)
Our discussers, in a further examina-
tion of the study conclude the effect
occurs at hourly averages well below
0.10 ppm.
Hopefully, EPA will present the
data and further analysis which led
to each of these four conclusions so
the technical community can judge
their relative merit.
Conclusion
We agree with Barth, et al., when
they state, "No responsible scientist or
public servant can argue for standards
that are known to be associated with
health hazards for a large proportion
of the population." Obviously, there
is a whole family of standards more re-
strictive than the ones we suggest
which would be more protective of
health. But, if there are no effects at
our suggested levels, more restrictive
standards have no benefits. We can
only ask again what hazards are as-
sociated with our suggested standards?
At the Editor's request we have
kept our comments short. However,
Harth et al., raised many points which
\ve have not discussed. Therefore, we
have prepared a more detailed response
am one,interested.
J. M. Heuss, G. J. Nebel, and J. M.
Colucci, General Motors Research Lab-
oratories, Warren, Michigan 48090.
References
1. Heuss, J. M., Nebel, G. J., and Colucci,
J. M., "National Air Quality Standards
for Automotive Pollutants: A Criti-
cal Review," J. Air Poll. Control
AXMIC.., 21, 535 (1971).
2 Culifitrmii Air Quality Data, Vol. II.
\o :<, May 1971.
3 (Joldsmith, ,/. R., and Landaw, S. A.,
"Carbon Monoxide and Human
Health,".Science, 162, 1352 (1968).
4. Larson, R. I., "A New Mathematical
Model of Air Pollutant Concentration
Averaging Time and Frequency," J.
Air Poll. Control Assoc., 19, 24 (1969).
5. Sterling, T. D., Science, 173, 676
(1971).
6. O'Donnell, R. D., "Recent Research
Into the Effect of Low Level Carbon
Monoxide Exposure on Pyschomotor
Performance in Healthy Humans,"
Proceedings, 17th Annual Meeting, In-
stitute of Environmental Sciences, Los
Angeles, Calif., April 1971.
7. Proposed Federal Ambient Air Quality
Standards, Report from the Technical
Advisory Committee to the California
Air Resources Board, March 10,1971.
8. Environmental Protection Agency.
"Requirements for Preparation, Adop-
tion, and Submittal of Implementation
Plans," Federal Register, 36, 15486
(1971).
9. Richardson, N. A. and Middleton.
W. C., "Evaluation of Filters for Re-
moving Irritants from Polluted Air,"
Heating, Piping, and Air Condition-
in g, 30,147 (1958).
December 1971 Volume 21, No. 12
789
-------
Smog Chamber Simulation of the Los Angeles Atmosphere
by
Jon M. Heuss
Environmental Science Department
General Motors Research Laboratories
Warren, Michigan
Presented at
Environmental Protection Agency
Scientific Seminar on Automotive Pollutants
February 10-12, 1975
Washington, 0. C.
-------
ABSTRACT
The finding that low-molecular-weight paraffins can react under certain
conditions to produce elevated ozone concentrations coupled with the
finding of an abundance of paraffins, presumably from natural gas leakage
and petroleum seepage, in Los Angeles has raised the question of what
level of ozone can ultimately be reached in this urban atmosphere.
Therefore, smog chamber experiments which include the contribution of natural
paraffins and simulate both present Los Angeles concentrations and
expected future concentrations have been conducted.
A 10-hydrocarbon mixture was made up, based on detailed hydrocarbon
analyses of Los Angeles air. This mixture was separated into two frac-
tions — a fraction representing controllable hydrocarbons and a fraction
consisting of light paraffins, presumably from natural gas leakage.
This mixture was irradiated at conditions representative of ozone-alert
days in Los Angeles. Then the effects of 50-, 80-, 90-, and 100-percent
control of the controllable hydrocarbon fraction were investigated,
together with varying degrees of nitrogen oxide control.
The results confirm that 0^ and 1^ formation are a function of both
hydrocarbon and NO concentrations and that NO inhibits ozone formation
X
at realistic atmospheric conditions. With even 100 percent control of
the controllable hydrocarbons in Los Angeles, these experiments indicate
ozone concentrations up to 1/10 of present maximum concentrations.
Hydrocarbon control was much more efficient in reducing both peak ozone
concentrations and ozone dosages than nitrogen oxides control. Hydrocarbon
control should also reduce peak nitrogen dioxide concentrations, but
will probably not affect average nitrogen dioxide concentrations.
The results are discussed in terms of the degree of hydrocarbon and
nitrogen oxides emissions control necessary to meet ozone and nitrogen
dioxide air quality standards in the Los Angeles Basin.
-------
INTRODUCTION
The determination of the degree of emission control needed to meet ozone
and nitrogen dioxide air quality standards in the Los Angeles Basin has
been the subject of considerable study. A number of approaches have
been used. They all have both advantages and limitations. Roll-back
models, while simple, ignore the complex chemistry which is known to
occur. Approaches which rely on the analysis of ambient data are also
hampered. They try to use differences in monitoring data which are due
to differences in meteorology to predict the effect of changes in emissions,
Smog chamber simulations overcome this problem. Either the meteorological
variables can be held constant and the effect of changes in emissions
can be measured directly or the emissions can be held constant and the
effects of meteorological variables can be studied. But, smog chambers
have limitations, too. An inability to reproduce the dynamic nature of
the atmosphere and the presence of poorly understood wall effects are
perhaps the most important. Nevertheless, most of our knowledge of
photochemical smog has come from laboratory studies, and results of
laboratory studies are the basis for the regulations on hydrocarbon
emissions.
Dimitriades1 smog chamber study has been used to predict the degree of
234
hydrocarbon and nitrogen oxides control needed in Los Angeles. ' '
However, the design of Dimitriades1 study did not take into account the
impact of light paraffins in the Los Angeles Basin. In 1962, Neligan
first reported a relative excess of low-molecular-weight paraffins in
the Los Angeles atmosphere as compared to the composition of auto exhaust.
This has since been confirmed by others, and the light paraffins have
been attributed to a combination of natural gas leakage, petroleum
fi 7 R
seepage, and gasoline evaporation losses. ' ' Furthermore, Altshuller
Q
et al. found that low-molecular-weight paraffins can react at high
hydrocarbon to nitrogen oxides ratios to produce ozone. This has also
been confirmed by others. ' These findings indicate that the contribu-
tion of light paraffins cannot be neglected, and raise the question of
what ultimate level of ozone can be reached in Los Angeles with even
complete control of present known hydrocarbon sources.
-------
Two series of experiments have been conducted in the GM Smog Chamber to
investigate the impact of paraffins on Los Angeles smog. First, experi-
ments with paraffin/nitrogen oxides mixtures were conducted which have
confirmed the reactivity of light paraffins at high hydrocarbon to
nitrogen oxides ratios; second, a series of experiments which include
the contribution of natural gas paraffins was conducted simulating both
present Los Angeles concentrations and expected future concentrations.
The objective was to determine the degree of hydrocarbon and nitrogen
oxides emissions control necessary to meet air quality standards for
ozone and nitrogen dioxide in Los Angeles.
EXPERIMENTAL
The experiments were conducted in the GM Smog Chamber, which is an
3
8.4 m stainless steel chamber. Spaced symetrically inside the chamber
are 19 Pyrex lamp tubes, each containing 10 blue fluorescent lamps, two
black lamps, and one filtered sun!amp. The facility has been described
12
in detail previously.
Before each run, the chamber air was purified. It was recirculated thru
a furnace containing a rhodium/alumina catalyst at 510°C for 16 hours at
a flow rate of 57 £pm. Irradiation of the dilution air with or without
added NO produced less than 0.01 ppm ozone.
^
Research-grade olefins and paraffins and research- or pure-grade aromatic
hydrocarbons were used. For the multicomponent hydrocarbon experiments,
a gaseous mixture representing natural gas constituents, and gaseous and
liquid mixtures representing evaporative plus exhaust emissions were
made up. Known volumes of the appropriate mixtures or pure gases were
measured out and added to the preheated chamber. The mixtures were
irradiated for six hours at 35°C. The light intensity, as measured as
the first-order rate constant for the photolysis of nitrogen dioxide in
nitrogen was 0.4 min" . The dilution air had a dew point of 15°C. Ozone
-------
was measured with a chemiluminescent ozone analyzer, calibrated with the
Federal Reference Method. Nitrogen dioxide was measured with an automated
analyzer, using the Saltzman method.
The sample volume withdrawn for analysis was replaced by catalytically
purified air that diluted the chamber contents by about 20 percent at
the end of a typical run.
Ozone Production from Paraffln/NO Mixtures
/\ * -^^~~^^" • • •
A series of screening experiments was conducted to measure the ozone
production from various paraffins as a function of hydrocarbon to nitrogen
oxides ratio. The paraffins studied were: methane, ethane, propane,
n-butane, isopentane, and n-hexane. In each case, 3 ppm of the paraffin
was irradiated with varying oxides of nitrogen concentrations between
0.02 and 1.5 ppm. The maximum 1-hour ozone concentrations are shown in
Figure 1 as a function of the initial NO concentration. Irradiation of
/\
methane/NO mixtures did not produce significant ozone. However, all
/\
the other paraffins studied did. Ethane, propane, and n-butane each
produced progressively more ozone over a wider range of initial NO
A
concentrations. The C, to Cg paraffins produced between 0.2 and 0.3 ppm
ozone over even a wider range of initial NO concentrations than ethane
9
and propane. These results confirm Altshuller et al.'s finding that
the HC/NO ratio at which ozone begins to form and at which ozone produc-
/\
tion maximizes decreases as the reactivity of the hydrocarbon increases.
The maximum ozone yields in this study are considerably lower than those
Q
reported for similar mixtures by Altshuller et al. although the HC/NO
/\
ratio at which ozone begins to form is somewhat lower. There are three
differences between the studies, which would have a bearing on the
maximum ozone production. The first is a spectral distribution effect.
Jaffe et al. have found a large effect of spectral distribution (at
constant Kd) in the propylene/NOx system. Irradiation in the wavelength
band below 360 nm increased reaction rates significantly, presumably due
-------
to other photolytic processes which lead to free radical production.
The irradiation in AHshuller's chamber overemphasizes the wavelength
band from 335 to 365 mn relative to either the sunlight distribution or
the GM Chamber distribution. ' ' This should lead to greater reactivity
in the Altshuller study. Secondly, the dilution air in Altshuller's
chamber contained background hydrocarbons (sufficient to produce 0.06
ppm oxidant when irradiated with 0.2 ppm NO ) which would contribute to
/\
greater ozone production. Finally, Altshuller's results were corrected
for dilution, whereas the results in Figure 1 were not. All three
factors would be expected to increase the ozone concentrations in Altshuller's
experiments. Despite the differences in absolute levels of ozone produced,
both studies indicate that low-molecular-weight paraffins have significant
reactivity at high ratios of hydrocarbons to nitrogen oxides.
Experimental Design of Los Angeles Simulation
The concept of this series of experiments was to irradiate a baseline
mixture representative of pollutant levels on the worst smog days in Los
Angeles and then investigate the effects of varying degrees of hydrocarbon
and nitrogen oxides emission control. The composition of the baseline
mixture (shown in Table I) was chosen based on the Los Angeles Air
Pollution Control District's monitoring data for early morning concentra-
tion on oxidant 'alert1 days from 1965 thru 1969. Carbon monoxide was
included because of recent evidence of its role in photochemical smog. '
The composition of the hydrocarbon fraction was chosen by comparing
O 1 "7 TO
measurements of the detailed hydrocarbon composition in Los Angeles *'
19 20
with measurements of the detailed composition of automotive exhaust '
21 22 23
and evaporative emissions. ' Stephens and Burleson concluded that
the hydrocarbon composition of ambient air resembles a mixture of auto
exhaust plus natural gas plus evaporative emissions. In addition,
Q
Altshuller et al. found that ten hydrocarbons account for about 80
percent of the nonmethane hydrocarbon loading in Los Angeles. Thus, it
appeared that a 10-hydrocarbon-mixture separated into two fractions --
one representing exhaust plus evaporative emissions and the other
natural gas -- would adequately simulate the Los Angeles hydrocarbon mix.
-------
The composition of the mixture chosen is shown in Table II. The exhaust
plus evaporative fraction represents the controllable hydrocarbons in
Los Angeles. The effects of 50-, 80-, 90-, and 100-percent reductions
in this controllable hydrocarbon fraction were investigated, together
with varying degrees of nitrogen oxide emission control. The baseline
carbon monoxide concentration was reduced along with controllable
hydrocarbon fractions since hydrocarbons and carbon monoxide are being
controlled to approximately the same degree.
RESULTS
Maximum Ozone Concentrations
The reaction profile of the baseline experiment is shown in Figure 2.
The nitrogen dioxide peaked in 90 minutes and the maximum ozone concentra-
tion of 0.40 ppm was produced in about four hours. The maximum 1-hour
ozone concentrations formed in all the experiments are shown in Figure
3. As the controllable hydrocarbons are reduced, the maximum ozone
concentrations are markedly reduced. On the other hand, reduction in
NO at a constant hydrocarbon level resulted in an increase in maximum
X
ozone concentrations before any reduction is achieved. These results
show that the maximum ozone concentration is not very sensitive to NO
over a wide range of NOV concentration. This differs markedly from
1
Dimitriades' results which showed a much more pronounced effect of NO .
A
However, Dimitriades used auto exhaust as the hydrocarbon source and did
not take into account the presence of natural gas paraffins. The difference
between this study and that of Dimitriades is attributed to the presence
of the light paraffin background moderating the effect of nitrogen
oxides.
These results confirm that with realistic atmospheric mixtures, hydrocarbon
control is much more efficient than NO control in reducing ozone. The
/\,
set of experiments with 100 percent reduction of the controllable hydro-
carbons confirms that a significant ozone concentration (up to 1/10 of
-------
the baseline result) can be produced from a mixture of methane, ethane,
propane, and butane, alone. Since the location of the ozone maximum in
the curves shifts to lower NO concentrations as hydrocarbons are reduced,
/\
these experiments also predict that reducing ozone by nitrogen oxide
control will be difficult, if not impossible.
Ozone Dosage
The ozone dosages for these experiments are shown in Figure 4. The
pattern for ozone dosages is similar to that for maximum ozone concentrat-
ions, indicating that the conclusions concerning maximum ozone concentra-
tions should hold for ozone dosages as well.
Maximum NOp Concentrations
The maximum 1-hour N02 concentrations are shown in Figure 5. Peak N02
concentrations are affected by both HC and NO control. Hydrocarbon
J\
reduction, by itself, significantly reduces peak N02 concentrations. As
expected, nitrogen oxides reduction further reduces peak N02 concentrations,
NO,, Dosage
The N02 dosage results are shown in Figure 6. In contrast to results
for peak N02 concentrations, N02 dosage was not affected by hydrocarbon
reduction. In this set of experiments, the N02 dosage was essentially
proportional to the initial NO concentration. Since these mixtures
3\
simulated both present-day concentrations and a wide range of possible
future concentrations, this result provides support for the assumption
that reductions in nitrogen oxides emission will result in approximately
proportional reductions in average N02 concentrations.
Meeting Air Quality Standards in Los Angeles
The application of this or any other laboratory study to the atmosphere
must be considered with extreme caution. However, the suitability of
-------
smog chamber experiments in simulating the atmosphere has been studied
24 25
by Altshuller et al. and Kopczynski et al. They collected samples
of downtown Los Angeles air in large plastic bags and exposed them to
natural sunlight. They found that the rates of hydrocarbon reaction
under these conditions were similar to those reported in laboratory
studies. They also found that the ozone concentrations produced in
their bag irradiations were comparable to those measured at a number of
nearby monitoring stations. They concluded that their results provided
a validation of the smog chamber technique for studying atmospheric
chemistry. It is heartening that the maximum ozone produced and the
time scale of the reaction for the baseline mixture of this study is
comparable to that observed in the atmosphere for similar mixtures.
While it is unlikely that the absolute concentrations produced in the
smog chamber would be directly applicable to the atmosphere, the use of
these results in a relative sense appears justified. That is, if one
wanted to reduce ozone concentrations in Los Angeles by 80 percent, the
combination of hydrocarbon and nitrogen oxides control which reduced the
baseline ozone concentration by 80 percent might well apply in the
atmosphere.
Some examples follow of how these results might be used to estimate the
hydrocarbon and NO control necessary to meet various air quality standards
/\
in Los Angeles. In order to apply this approach, the percent reductions
in Oo and N02 necessary to meet various air quality standards must be
known. Since the baseline mixture is representative of late 1960's
atmospheric concentrations, the comparable maximum concentrations of Oo
and NOp during the late 1960's are needed. These are shown in Table III,
along with the Federal and California air quality standards and the
pc
percent reductions required. These percent reductions are subject to
a certain degree of uncertainty, since the measurement of both N0~ and
27 28
Oo have been questioned. ' The EPA has not yet specified a new
reference method for NOp, and the Federal Reference Method for ozone has
been called into question. It is possible that the existing ambient
measurements may have to be corrected and/or that the air quality standards
for 0., and NOp may be changed.
-------
In any case, the 03 and N02 reductions specified in Table II! were
applied to the smog chamber simulation with the results shown in Figures
7 and 8. The hydrocarbon reduction required to meet the Federal oxidant
standard, and the NO reduction required to meet the Federal N02 standard
are shown in Figure 7. This figure emphasizes the effect of nitric
oxide inhibition on meeting the ozone standard. If NO were not controlled,
only 80 percent hydrocarbon control would be necessary to meet the
Federal ozone standard. If 75 percent NO control were required, over 95
percent HC control would be necessary. Any combination of HC and NO
/^
control which ends up in the cross-hatched area would simultaneously
meet both the Federal 0^ and N02 standards. The minimum emission reductions
necessary are then 90 percent for HC and 45 percent for NO . It is both
A
interesting and unexpected that this result is similar to that obtained
from simple roll-back calculations.
The emission reductions required to meet the California air quality
standards are shown in Figure 8, along with the emission reduction
necessary to meet a 0.5 ppm/1-hour N02 standard. The emission reduction
necessary to meet the California air quality standards are 87 percent
for HC and 45 percent for NO . On the other hand, if there were a
^\
short-term N02 standard of 0.5 ppm, emission reduction of 75 percent for
HC and none for NO would be sufficient. Obviously, the degree of
A
emission control required is highly dependent on the choice of air
quality standards for both 03 and NO,,.
CONCLUSIONS
These experiments have shown that the contributions of natural gas paraf-
fins is important in photochemical smog and should be considered in any
control strategy decisions. In the future as other hydrocarbons are
controlled in Los Angeles, the importance of the contribution of natural
gas leakage and petroleum seepage will grow. These results confirm that
ozone formation is a function of both hydrocarbon and nitrogen oxides
concentrations and that nitric oxide inhibits ozone formation under
8
-------
realistic atmospheric conditions. Hydrocarbon control is much more
efficient than NOX control in reducing Og. In fact, this study indicates
that reducing 03 by NO control will be difficult, if not Impossible.
Hydrocarbon control, by itself, will reduce peak NOp concentrations but
will probably not affect average N02 concentrations.
-------
Table I. Composition^ of Baseline Mixture
Nitric Oxide 0.55 pptn
Carbon Monoxide 15.0 ppm
Hydrocarbons 8.1 ppmC
10
-------
Table II. Hydrocarbon Composition of Baseline Mixture
Exhaust Plus
E vajjp ra ti ve Em i s s i on s
0.025 ppm ethane
0.025 ppm propane
0.145 ppm n-butane
0.125 ppm isopentane
0.17 ppm ethylene
0.07 ppm propylene
0.09 ppm benzene
0.165 ppm toluene
0.09 ppm m-xylene
Natural Gas
2.8 ppm methane
0.25 ppm ethane
0.11 ppm propane
0.04 ppm n-butane
11
-------
Table III. Reductions in Ozone and Nitrogen Dioxide Required
in Los Angeles Basin to Meet Various Air Quality Standards
Air Quality Standard
Agency Concentration
Maximum Observed Reduction
Averaging Concentrations Required
Time (1965-1969 Average) (percent)
Ozone
Federal
California
0.08
0.10
1 hour
1 hour
0.62
0.62
87
84
N i t r o g e n D i p x i d^ e
Federal 0.05 Annual Average 0.09
California 0.25 1 hour 0.75
45
67
12
-------
0.30
0.25
3 PPM n-HEXANE
PPMISOPENTANE
.a
0.20
// 3 PPM n-BUTANE
o
•z.
o
o
0.15
0.10
li.
3/l/ X ""*
\Y
3 PPM ETHANE
3 PPM PROPANE
0.05
/\
\
\
\
./
/
0
AIR QUALITY STANDARD
\
\
\
3 PPM METHANE \
0.25 0.50 0.75
1.00
1.25 1.50
INITIAL NOCONC., PPM
A
Figure 1. Maximum Ozone Produced from Irradiation
of Paraffin/NO Mixtures
/\
13
-------
0
Figure 2. Reaction Profile of Irradiation
of Baseline Mixture
14
-------
0.40
0.35
BASE! ;NL
Ml XT -7E
0.30
0.25
50% HC CUMTROi
o
o
o
a:
ZD
O
0.20
0.15
/O.IO
0.05
O —
•o
80% HC CONTROL
90% HC CONTRC
o 100% HC CONTROL
-,_ o
0
0.1
0.2
0.3
0.4
- o
0.5
0.6
INITIALNOYCONC., PPM
A
Figure 3. Maximum One-Hour Ozone Concentrations
Produced from Irradiation of Multi-
component Hydrocarbon/NO Mixtures
/\
15
-------
1.8
n:
x
g- 1.2
o
-------
0.40
0.35
BASELINE
MIXTURE
0.30
0.25
o
o
o
cf
0.20
50% HC CONTROL
90% HC CONTROL
x 0.15
0.10
0.05
-- o
/
100% HC CONTROL
o
0
0.1
Figure 5.
0.2
0.3
0.4
0.5
INITIALNOCONC.,PPM
A
Maximum One-Hour Nitrogen Dioxide Concentra-
tion Produced from Irradiation of Multi-
component Hydrocarbon/NO Mixtures
/\
17
0.6
-------
0
0.2 0.3 0.4 0.5
INITIALNOXCONC. , PPM
Figure 6. Nitrogen Dioxide Dosages in the Irradiation
of Multicomponent Hydrocarbon/NO Mixtures
18
-------
100
90
i
o
Q
UJ
o
70
TO MEET 0 STD.
0
0
>.
I ^TOMEETN0STD.
25 50 75
NO REDUCTION -%
100
Figure 7. Emission Reductions Necessary to Meet Federal
Air Quality Standards in the Los Angeles Basin
19
-------
100
75
5 50
ID
O
25
0
— s 0.5ppmN02
\
\
\
\
\
0
\
I
X25 ppm NO,
I
25 50 75
NO REDUCTION (%)
100
Figure 8. Emission Reductions Necessary to Meet Other
Air Quality Standards in the Los Angeles Basin
20
-------
REFERENCES
1. B. Dimitriades, "Effects of Hydrocarbon and Nitrogen Oxides on
Photochemical Smog Formation," Environ. Sci. Techno!., (5 (1972),
p. 253.
2. "A Critique of the 1975 Federal Automobile Emission Standards for
Hydrocarbons and Oxides of Nitrogen," Panel on Emissions Standards
and Panel on Atmospheric Chemistry, Committee on Motor Vehicle
Emissions, National Academy of Sciences (1973).
3. "Air Quality and Automobile Emission Control," a report by the
Coordinating Committee on Air Quality Studies, National Academy
of Sciences, National Academy of Engineering, September 1974.
4. "The Effects of Proposed Light-Duty Motor Vehicle Emission Standards
on Air Quality," Staff Report 74-21-4A, Air Resources Board, State
of California, November 13, 1974.
5. R. E. Neligan, "Hydrocarbons in the Los Angeles Atmosphere," Arch.
Environ. Health. 5_ (1962), p. 581.
6. A. P. Altshuller and T. A. Bellar, "GC Analysis of Hydrocarbons in
the Los Angeles Atmosphere," J. Air Pollut. Control Assoc., J3_
(1963), p. 81.
7. E. R. Stephens, E. F. Darley, and F. R. Burleson, "Sources and
Reactivity of Light Hydrocarbons in Ambient Air," Proc. Amer. Petrol,
Inst.. Division of Refining, 47 (1967), p. 466.
8. A. P. Altshuller, W. A. Lonneman, F. D. Sutterfield, and S. L.
Kopczynski, "Hydrocarbon Composition of the Atmosphere of the Los
Angeles Basin — 1967," Environ. Sci. Techno!.. J5 (1971), p. 1009.
21
-------
9. A. P. Altshuller, S. L. Kopczynski, D. Wilson, W. Lonneman, and
F. D. Sutterfield, "Photochemical Reactivities of n-Butane and
other Paraffinic Hydrocarbons," J. Air Pollut. Control Assoc.. 19.
(1969), p. 787.
10. W. E. Wilson and G. F. Ward, "The Role of Carbon Monoxide in Photo-
chemical Smog. I. Experimental Evidence for Its Reactivity," pre-
sented at 160th National Meeting, American Chemical Society, Chicago,
Illinois, September 1970.
11. J. J. Bufalini, B. W. Gay, and S. L. Kopczynski, "Oxidation of
n-Butane by the Photolysis of N02," Environ. Sci. Techno!.. 5_
(1971), p. 333.
12. C. S. Tuesday, B. A. D'Alleva, J. M. Heuss, and G. J. Nebel, "The
General Motors Smog Chamber," Research Publication GMR-490, presented
at the Air Pollution Control Association Annual Meeting, Toronto,
Canada, June 1965.
13. R. J. Jaffe, F. C. Smith, and K. W. Last, "Study of Factors Affecting
Reactions in Environmental Chambers," Report LMSC-D401598, Lockheed
Missies and Space Company, Sunnyvale, California, April 1974.
14. M. W. Korth, A. H. Rose, and R. C. Stahman, "Effects of Hydrocarbon
to Oxides of Nitrogen Ratios on Irradiated Auto Exhaust — Part I,"
J. Air Pollut. Control Assoc.. J^ (1964) p. 168.
15. M. C. Dodge and J. J. Bufalini, "Photochemical Smog and Ozone Forma-
tion," Adv. Chem. Ser.. No. 113, American Chemical Society, 1972,
p. 232.
16. K. Westberg, N. Cohen, and K. W. Wilson, "Carbon Monoxide: Its
Role in Photochemical Smog Formation," Science. 171 (1971), p. 1013.
17. Air Quality Criteria for Hydrocarbons, National Air Pollution Control
Administration Publication No. AP-64, March 1970, p. 3-8.
22
-------
18. W. A. Lonneman, T. A. Bellar, and A. P. Altshuller, "Aromatic
Hydrocarbons in the Atmosphere of the Los Angeles Basin,"
Environ. Sci. Techno!.. 2:, (1968), p. 1017.
19. W. E. Morris and K. T. Dishart, "The Influence of Vehicle Emission
Control Systems on the Relationship Between Gasoline and Vehicle Exhaust
Composition," presented at ASTM Workshop, Toronto, Canada^ June 24, 1970.
20. M. W. Jackson, "Effects of Some Engine Variables and Control Systems
on Composition and Reactivity of Exhaust Emissions," from Vehicle
Emissions II, SAE Progress in Technology Series, 12, 1967.
21. D. T. Wade, "Factors Influencing Vehicle Evaporative Emissions,"
from Vehicle Emissions III, SAE Progress in Technology Series, 14,
1971.
22. M. W. Jackson and R. L. Everett, "Effect of Fuel Composition on
Amount and Reactivity of Evaporative Emissions," from Vehicle
Emissions III, SAE Progress in Technology Series, J4., 1971.
23. E. R. Stephens and F. R. Burleson, "Analysis of the Atmosphere for
Light Hydrocarbons," J. Air Pollut. Control Assoc.. 17. (1967), p. 147.
24. A. P. Altshuller, S. L. Kopczynski, W. A. Lonneman, and F. D.
Sutterfield, "A Technique for Measuring Photochemical Reactions in
Atmospheric Samples," Environ. Sci. Techno1. 4, (1970), p. 503.
25. S. L. Kopczynski, W. A. Lonneman, F. D. Sutterfield, and P. E. Darley,
"Photochemistry of Atmospheric Samples in Los Angeles," Environ.
Sci._ Techno!.. 6 (1972) p. 342.
26. "Ten-Year Summary of California Air Quality Data, 1963-1972" report
of the Division of Technical Services of the State of California Air
Resources Board, January 1974.
27. Federal Register, 3£, June 8, 1973, p. 15174.
28. California Air Resources Board Bulletin, Vol. 5, December 1974.
23
-------
A Further Response to EPA's Discussion of
"National Air Quality Staadards for Automotive Pollutants;
A Critical Review"
J. M. Heuss, G. J. Nebel, and J. M. Colucci
Fuels and Lubricants Department
Research Laboratories
General Motors Corporation
Warren, Michigan
-------
A Further Response to EPA^ Discussion of
"National Air Quality Standards for Automotive Pollutants;
A Critical Review"
J. M. Heuss, G. J. Nebel, and J. M. Colucci
When we published the above paper in the September 1971 issue of the
Journal of the Air Pollution Control Association, it was immediately followed
by a Discussion defending the Standards, authored by Messrs. Barth, Romanovsky,
Knelson, Altschuller, and Horton of the Environmental Protection Agency. We
disagreed with many of their comments and replied with a Letter to the Editor
2
that was published in the December 1971 issue of the APCA Journal. This report
supplements our letter, which was necessarily limited to a few thousand words.
We recommend that it be read in conjunction with our original paper, the EPA
Discussion, and our Letter to the Editor . . . copies of which are attached.
General Comments
The Discussion by Barth, et al., is the only public statement from EPA
which explains the basis for the National Air Quality Standards. The April
30, 1971 Federal Register, in which the Standards were promulgated, states
only that they are based upon the published air quality criteria documents.
However, those document? were written to summarize the current state of
knowledge about the effects of pollutants, not to define air quality standards.
The important step from air quality criteria to air quality standards has never
been officially documented. This is most unfortunate, because as Stokinger
recently pointed out, "Standards, as well as the criteria upon which they are
3
based, must be completely documented." Since Barth, et al's., Discussion is
the closest EPA has come to disclosing the reasons behind its decisions, it
is important to review it in detail.
1
-------
Two more general comments. Our discussers contend that our basic premise
is that air quality standards should be formulated in such a manner that they
do not impose undue economic burdens. This is not true. Economics did not
enter into our judgment as to what standards are necessary to adequately pro-
tect public health. However, we do not agree with the simplistic idea that
if a given standard is satisfactory, a more restrictive standard would be
better. Rather, we agree with the Technical Advisory Committee of the
California Air Resources Board when it states, "Setting standards more
stringent than those Justified by the data on adverse effects delays obtain-
ing satisfactory air quality by channeling effort and money into non-essential
4
controls." EPA has also espoused this reasonable philosophy in discussing
its involvement with the APRAC program: "The interest of the CRC in this
support is basically the same as EPA's -- to establish a firm foundation for
standards and regulations so as to obviate unnecessary economic penalties
through over-restrictive standards."
Finally, we would point out that Congress provided two separate standards
for each pollutant: (1) a primary standard to protect the public health with
an adequate safety margin; and (2) a secondary standard to protect the public
welfare against any known or anticipated adverse effects. The primary
standard is to be met by a specific date, whereas the secondary standard is
a goal to be met as soon as practicable. For reasons which have never been
made public, EPA set the primary and secondary standards equal for the four
automotive pollutants we discussed. This must mean that EPA cannot anticipate
any adverse effects at concentrations below the present standards. This in
turn indicates to us that the primary standards provide more protection than
is necessary.
-------
Carbon Monoxide
Barth, et al., now cite studies other than the controversial Beard and
Wertheim work to support the National CO Standard. Most of these were
discussed in the CO Criteria Document. However, they fail to point out
that these studies, including those of Ayres, Astrup, Mills and Edwards,
and of McFarland, showed effects only at exposures far above either the
National Standard or our suggested standard. When Barth, et al., quoted
DuBois1 conclusion that there may not be a threshold for CO effects, they
failed to point out that the lowest exposure level in each case DuBois
cited was well above both the National Standard and our suggested
standard. The National Standard has, in fact, created a new definition
for toxicologists as to what constitutes a low CO exposure.
Barth, et al., also refer to the epidemiological studies of Goldsmith
and co-workers as cause for concern about the levels of CO in the atmosphere,
Cohen, Deane, and Goldsmith compared CO concentrations with the percent of
hospitalized myocardial infarction patients who died during 1958 in hospital!
in two sections of the Los Angeles Basin. They divided the weeks of the
year into quartiles ranked by CO concentration and found a significantly
higher fatality rate in the high CO area than in the low CO area during
the period (quartile) of highest CO exposure. As the data in the following
Table indicate, the fatality rate in the presumed high CO area increased
with increasing CO, while the fatality rate in the low CO area actually
decreased with increasing CO. The division of the Basin into areas of pre-
sumed high and low CO was based on LA APCD monitoring data for 1955. When
all the LA County CO data from 1956 to 1967 are considered, the dividing
line drawn by Cohen, et al., cannot be substantiated. Since it is unlikely
-------
that there was a difference in the average CO exposure between the supposedly
high CO and low CO areas, and since the fatality rate actually decreased with
increasing CO in the low area, we find it hard to conclude that CO con-
tributed to the deaths from myocardial infarction.
Table I
Data from Table 2 of Reference 6
Rearranged and Expressed as Quartile Averages
Quartile: 1 2 3 4
CO - Weekly Basin
Average, ppm 5.7 6.4 7.6 9.9
Average Admission
CFR, %
High Area 26.3 24.3 27.4 31.4
Average Admission
CFR, %
Low Area 23.1 26.8 19.3 17.7
Q
Earth, et al., also refer to the recent Hexter and Goldsmith study
which suggested a possible effect of CO on death rates. By adding a term,
log CO, to their multiple-regression equation they were able to explain
37.1 percent of the original variance compared with 36.7 percent for the
Q
model without any CO term. As pointed out by Hamming, et al., other
pollutants which have previously been related to excess deaths are correlated
with CO and might be expected to be responsible for the effect. In addition,
McDonald and Schwing have recently shown that the multiple-regression
technique can lead to erroneous results when the independent variables
are correlated. They used a technique called "ridge regression" to check
the stability of regression coefficients. This should be a very powerful
tool to check the validity of the Hexter and Goldsmith work.
-------
NOg
We agree with Barth, et al., that the continuous Griess-Saltzman method
is marginal, but our experience indicates that the Jacobs-Hochheiser method
is worse than marginal. Barth, et al., claim that the J-H method can be
controlled satisfactorily, but we believe the experience of the National
Air Sampling Network has shown that this is not the case. At low concentra-
tions typical of the atmosphere, the J-H method measures total oxides of
nitrogen more closely than it does N02. Barth, et alr, claim that at the
time of the study the NO concentrations in Chattanooga were low relative to
NOg. We have been unable to find any data to support this conclusion. Until
such data are presented, this assertion should not be accepted as fact. More-
over, the CAMP data for other U. S. cities suggest that it is unlikely that the
NO concentrations in. Chattanooga were low relative to NOa, particularly in the
two control areas away from the TNT plant. It is precisely the unexpected
medical results from the two control areas which are the basis for the NOa
standard.
Barth, et al., justify including School 3 in the high NOa area even
though the average NOa exposure there was identical to the Control 1 area
because the NOa standard deviation was higher at School 3. They claim that
this means that there were both higher and lower NOa exposures at School 3
and that the higher values would have relatively more effect on health.
However, they disregard the actual data in the Chattanooga study which
showed that the 90th percentile NOa concentrations were almost identical
for the School 3 and Control 1 areas.
Our discussers indicate that the distinction between the two control
areas used to delineate one as an "intermediate" area and the other as a
"low" area was made in the protocol for the Pearlman study. However, they
do not indicate why this same distinction was not made when analyzing the
-------
data from the two earlier portions of the Chattanooga Study. We object to
this "change of horses in midstream."
Hydrocarbons
Even though the hydrocarbon-oxidant relation which Earth, et al., defend
is no longer used by EPA, we still wish to respond to their comments.
They claim that we used "simplicity in statistical reasoning to imply
that the combine^ probability of exceeding
in 100 years" because we ignored the fact
to occur more often than 17» of the time. 1
that the maximum oxidant potential is reac
the oxidant standard is only once
that critical smog incidents tend
lowever, our source for the fact
\ed less than 1% of the time is the
Hydrocarbon Criteria Document. It states: "Since Fig. 5-3 contains only 11%
of the days for these cities for a 3-year period, it follows that for all days
in the 3-year period the maxium oxidant potential was achieved on less than
1 percent of the days." This conclusion is not readily apparent from Fig.
5-3 (reproduced as Figure 3 of our paper) because the many points which lie
below 0.07 ppm oxidant or 0.3 ppm C non-methane hydrocarbon are not shown.
The maximum oxidant potential may be reached much less than 17» of the time
since the 11% referred to in the quotation above may be in error. There may
be as many as 3,000 days of data represented in Fig. 5-3 (data for 3 years
at 3 different CAMP stations plus six months at one Los Angeles station).
The 11% may refer to all valid data days rather than to all days. Since the
hydrocarbon-oxidant relation was derived by plotting all the data, drawing a
line around it, and calling that line the "maximum oxidant potential," one would
expect that the maximum oxidant potential would be that oxidant concentration
reached only a very small percentage of time at any given hydrocarbon
concentration.
-------
The probability of exceeding the oxidant standard is the probability of a
given hydrocarbon concentration occurring times the probability of a given oxi-
dant concentration being formed at that hydrocarbon level. Our "simple reason-
ing" is that in a location where the hydrocarbon standard is met, the probability
of a hydrocarbon concentration above the standard is, by definition, once per
year. This must be multiplied by the probability of reaching the maximum oxi-
dant potential for that HC level which, according to the Hydrocarbon Air Quality
Document, is less than 1%. Thus, the probability of exceeding the oxidant
standard is less than once per hundred years at a location where the hydro-
carbon standard is met. At hydrocarbon concentrations below the standard, the
maximum oxidant potential is below the oxidant air quality standard so the
probability of exceeding the oxidant standard can be considered zero for all
hydrpcarbon concentrations below the hydrocarbon standard.
Barth, et al., state that, "The sam* meteorology that favors the formation
of oxidant favors the accumulation of hydrocarbons during the time period of
the hydrocarbon standard." This simplistic statement sounds reasonable, but
ignores the fact that there are two processes involved in the formation of
oxidant. One is the accumulation of primary pollutants and the other is their
chemical reaction to produce oxidant. Temperature inversions and low wind
speeds favor the accumulation of primary pollutants, whereas sunlight and
ambient temperature determine how rapidly they react. All the meteorological
variables must be favorable to form the highest oxidant concentrations. This
is rarely the case, however, because the highest concentrations of primary
pollutants occur in winter when sunlight intensity and ambient temperatures
are low. For example, in Philadelphia the highest (6-9 a.m. average) non-
methane hydrocarbon concentration for the entire year of 1967 was 6.0 ppm C
and occurred on January 24, a day when no ozone was formed. 96% control would
-------
have been required that day to meet the hydrocarbon air quality standard.
Such effort would have been entirely wasted since no ozone was formed anyway.
This is why we suggested that the hydrocarbon air quality standard is un-
necessary but that hydrocarbon emissions be controlled to whatever extent is
necessary to meet the oxidant air quality standard.
Earth, et al,, admit that the non-methane hydrocarbon data are imprecise,
but they do not appear to realize that the probable errors are of the same
magnitude as the hydrocarbon standard. This arises from the need to make two
measurements and subtract them, and from the fact that the charcoal adsorbent
is not perfect. We continue to believe that this imprecision affected many of
the low non-methane HC values that went into the oxidant model. As we pointed
out in the paper, the fact that there were 58 days during 1967 in which the
non-methane HC concentrations in Philadelphia were NEGATIVE is strong evidence
that there were many other days in other years and in other CAMP stations in
which the non-methane HC concentrations were seriously underestimated.
(Similarly, there were many days in which the concentrations were over-
estimated.) When the CAMP data were searched to find the LOWEST non-methane
HC which occurred on days of elevated oxidant, the underestimated values must
have been selected. Since these data established the upper limit line of the
model, the hydrocarbon standard was set lower than was really necessary.
Earth, et al., claim that weekend data dominate the lower end of the
upper limit curve because less oxidant is formed on weekends. Fortunately,
their claim can be checked. We compared the maximum hourly oxidant on week-
ends versus weekdays at two Los Angeles monitoring sites for the years 1967
to 1969. As shown in Table II, the maximum oxidant concentrations on week-
ends and weekdays are not significantly different even though, as our paper
-------
shows, the 6-9 a.m. hydrocarbon concentration* are corisii*»«bly lower on
weekends. We suggested that it was improper t* us* wMiwnsl data because
the HC-Oxidant proportionality factor is different for weekdays than for
weekends. Therefore, it is unduly restrictive to derive a standard pre-
dominantly from weekend data and then apply it to weekdays when the maximum
hydrocarbon concentrations occur.
Table II
Average of Maximum Hourly Oxidant Concentration*
on Weekdays apd Weekend* in
Weekdays
Weekends
Weekdays
Weekends
1947 19*8 1%9
0.11 0.0» 0.09
0.09 0.10 0.09
Azusa
1967 If6$ 1969
0.17 0.13 0.15
0.16 0.14 0.15
Earth, et al., claim that the data for July 18, 1967 support the
observational model. We cannot understand how a 6-9 a.m. average non-
methane HC concentration of 1.0 ppm C can be "... indicative of the
HC level responsible for the oxidant level later in the day ..." when
the HC level during the hour of maximum oxidant was 2.3 ppm C. Since
the hydrocarbons present at the time of maximum oxidant have already re-
acted somewhat, the level earlier that was responsible for the oxidant
-------
must have been greater than 2.3 ppm C. It is clear that the 6-9 a.m.
average of 1.0 ppm C at the monitoring site was not the same hydrocarbon
which reacted to produce the oxidant. It must have come from another
location.
One of the basic assumptions of the HC observational model is that
the composition at a specific point is a good indication of the composi-
tion of the air mass covering a large area. The data of Schuck, Pitts,
12
and Wan are cited to support this contention. However, Schuck, Pitts,
and Wan's conclusion only applies to averaged data. The average concentra-
tion at a point can be related to the average concentration at another
point, but on any specific day there is no discernible relation between
concentrations at one point and those at another (as the July 18, 1967
example illustrates). Unfortunately, the HC standard is derived from a
few specific days rather than the average of many days. Thus, the data
used to set the standard violate one of the model's basic assumptions.
This is why we suggested using all the' data to derive the standard. Most
of the arguments used by Earth, et al., to support the observational model
apply to the general case. They continually ignore the fact that the HC
standard was derived from a small fraction of the data available which
violates one or more of the model's assumptions.
In the observational model, Earth, et al., have defined the days
which are meteorologically favorable for oxidant formation as those in
which a maximum oxidant concentration of 0.1 ppm or higher is formed
from the lowest concentrations of 6-9 a.m. non-methane hydrocarbons. As
we have shown in our paper, and have reemphasized above, these days tend
to be those having erroneously low non-methane concentrations and those
days on which the 6-9 a.m. HC average is not representative of the
10
-------
hydrocarbon responsible for the oxidant present later at that point. When
the hydrocarbon-oxidant proportionality factor derived from a few specific
days is applied to the general case, it greatly over-estimates the degree
of hydrocarbon control necessary. It would be more logical to define the
meteorologically favorable days as those which have the highest oxidant
concentrations, and then decide what degree of hydrocarbon control is
necessary to meet the oxidant standard. This appears to be what EPA is
going to do to implement hydrocarbon controls; however, as we pointed out,
the derivation of this new model has still not been made public.
Photochemical Oxidants
We disagree with Barth, et al's., claim that we misquoted Higgins
13
and McCarroll's summary of the Koonitz study. By referring to page 90
of Reference 13, the reader will see that no direct correlation between
total oxidants and athletic performance was claimed, but that chanR.es in
either oxidant or temperature appeared to have an effect; and, finally,
that there was a lack of correlation of athletic performance with the
absolute pollution level. We wonder why Barth, et al., referred to "a
paucity of data" when the number of individual races was much higher in
Koonitz's study than in Wayne's study.
Barth, et al., approach the question of background concentrations
by assuming that detrimental effects of oxidant on public health have been
noted, and therefore that man-made sources must be controlled to an even
higher degree than in the absence of background levels. As we pointed out
in our paper, neither we nor California authorities agree that effects
detrimental to the public health have been established by EPA. Before
concluding that man-made sources must be controlled to such a high degree,
11
-------
we feel that background levels and health effects must be firmly established.
Our discussors stress that they are implementing major research programs to
develop missing scientific data. It see/is to us that one major program which
must be undertaken is to determine the natural background level of ozone. If
the oxidant standard is, in fact, at the background level and therefore un-
achievable, the "consequences of judgmental error" will be more than economic.
The efforts to control other pollutants which do have public health effects
will suffer from a gross misdirection of control effort.
12
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REFERENCES
1. Heuss, J. M., Nebel, G. J., and Colucci, J. M., J. Air Poll. Control
A88QC..21. 535 (1971).
2. Heuss, J. M., Nebel, G. J., and Colucci, J. M., J. Air Poll. Control
Assoc., n, 788 (1971).
3. Stokinger, H. E., Science. 174. 662 (1971).
4. Proposed Federal Ambient Air Quality Standards. Official Report from the
Technical Advisory Committee to the California Air Resources Board,
March 10, 1971.
5. Statement For the Record, Involvement of the Environmental Protection
Agency in the Activities of the Air Pollution Research Advisory
Committee of the Coordinating Research Council, Appendix of EPA
Public Hearings on Automobile Emission Standards, May 6-7, 1971.
6. Cohen, S. I., Deane, M., and Goldsmith, J. R., Arch. Environ. Health.
i£, 510 (1969).
7. Air Quality Criteria fo.r Carbon Monoxide. National Air Pollution
Control Administration Publication No. AP-62, March 1970.
8. Hexter, A. C. and Goldsmith, J. R., Science. 172. 265 (1971).
9. Mosher, J. C., Brunelle, M. F., and Hamming, W. J., Science. 173,
576 (1971).
10. McDonald, G. C. and Schwing, R. c., "Instabilities of Regression
Estimates Relating Air Pollution to Mortality," presented at the
Symposium of the International Association for Statistics in Physical
Sciences on Statistical Aspects of Pollution Problems at the Harvard
Business School, September 1971. GM Research Publication No. 1124.
11. Air Quality Criteria for Hydrocarbons. National Air Pollution Control
Administration Publication No. AP-64, March 1970.
12. Schuck, E. A., Pitts, J. N. and Wan, J. K. S., Air and Water Pollut.
Int. J.. W, 689 (1966).
13. Koonitz, C. H., as reported by Higgins, I.T.T. and McCarroll, J. R.,
in "Development of Air Quality Standards," A. Atkisson and R. S.
Gaines, eds., Merrill Publ. Co., Columbus, Ohio, 1970, p. 90.
13
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INHIBITION OF ATMOSPHERIC PHOTOOXIDATION
OF HYDROCARBONS BY NITRIC OXIDE
William A. Glasson and Charles S. Tuesday
Reprinted from
Environmental
Science & Technology
Vol. 4, No. 1, January 1970
Research
Laboratories
General Motors Corporation
-------
Reprinted from
Science 8* Technology
Vo1' 4' JanuarV 1970, Pages 37-44
Copyright 1969 by the American Chemical
Society and reprinted by permission of
the copyright owner
Inhibition of Atmospheric Photooxidation
of Hydrocarbons by Nitric Oxide
William A. Glasson and Charles S. Tuesday
Fuels and Lubricants Department, General Motors Research Laboratories, Warren, Mich. 48090
• The effects of nitric oxide concentration on the atmospheric
photooxidation of propylene, ethylene, f/wts-2-butene, iso-
butene, and m-xylene have been investigated using long-path
infrared spectrophotometry. Low concentrations of nitric
oxide increased the photooxidation rate, while higher concen-
trations inhibited the rate of hydrocarbon photooxidation
measured either by hydrocarbon disappearance or product
formation. The nitric oxide concentration necessary for the
maximum photooxidation rate for a given hydrocarbon
concentration decreased as the hydrocarbon concentration
decreased, but, for the olefins studied, it was relatively in-
dependent of reactivity or structure. Decreased concentra-
tions of hydrocarbon consistently decreased the rate of
hydrocarbon disappearance and product formation at all
nitric oxide concentrations investigated. The results of this
investigation, together with atmospheric analyses, have
established that nitric oxide inhibition is important in the
photochemistry of polluted atmospheres.
Nitric oxide and nitrogen dioxide promote as well as
inhibit the atmospheric photooxidation of olefins.
Nitric oxide has been shown to promote or inhibit the photo-
oxidation rates of /ran.s-2-butene (Tuesday, 1961), ethylene
(Altshuller and Cohen, 1964), 2,3-dimethyl-2-butene (Tues-
day, 1963), and propylene (Altshuller, Kopczynski, et al.,
1967; Romanovsky, Ingels, et al., 1967) depending on the
concentration of nitric oxide. Nitrogen oxide inhibition and
promotion of oxidant formation in hydrocarbon photo-
oxidations have been reported by Haagen-Smit and Fox
(1956) and Stephens, Hanst, et al. (1956), as well as the other
investigators given.
Although these studies established that nitric oxide and
nitrogen dioxide inhibit olefin photooxidations and smog
symptoms of hydrocarbon photooxidations, the general im-
portance of the inhibition could only be inferred, since the
various studies were carried out with a variety of reactant
concentrations, some substantially higher than normal
atmospheric levels. A study has been carried out, therefore,
with atmospheric concentrations of hydrocarbon and nitric
oxide (Korth, Stahman, et al., 1964; Neligan, 1962) to estab-
lish the importance of nitric oxide inhibition in the photo-
chemistry of polluted atmospheres and to investigate the
reactions responsible for the inhibition.
Experimental
Apparatus. Analyses were made with a 3-meter base path
multiple reflection cell used in conjunction with a modified
Perkin-Elmer Model 21 infrared spectrophotometer and
attached ordinate scale expansion unit. Analyses were made
with a 120 meter path length and five-fold ordinate scale
expansion. Irradiation was supplied by a number of black
light fluorescent bulbs (F96T8/BL) mounted in the long-path
cell, which also served as the reaction vessel. Details of the
cell and the irradiation system have been given elsevwhere
(Tuesday, 1961).
Chemicals. Airco "prepurified" nitrogen and U.S.P. oxygen
were routinely used. The hydrocarbons used were Phillips
Petroleum research grade. Matheson nitric oxide was used,
after purification by passage through Ascarite and several
bulb-to-bulb distillations. Nitrogen dioxide was prepared, as
needed, by the thermal oxidation of nitric oxide, as described
previously (Tuesday, 1963).
Procedure. The long-path cell was evacuated to a pressure
less than 10^ of Hg before each run. Reactants at known pres-
sures were expanded into the cell from an attached glass
vacuum system. Nitrogen was then added to about 600 mm of
Hg. After the addition of oxygen, (155 mm of Hg), the final
pressure was brought to 760 mm of Hg with the small amount
of "additional nitrogen required.
The time from the addition of oxygen to the start of irradia-
tion was 50 ± 2 min. for the ethylene photooxidation ex-
periments, and 32 ± 3 min. for the other hydrocarbons
studied. The nitrogen dioxide concentrations due to thermal
oxidation can be calculated from the various experiments
from the nitric oxide concentrations and the times given above,
in the integrated second-order rate equation, using the rate
constant of Glasson and Tuesday (1963). The thermal oxida-
tion of nitric oxide occurring in the cell prior to irradiation
was no more than 1 % for initial nitric oxide concentrations of
1 p.p.m. or less.
The rate of hydrocarbon disappearance, as well as the rate
. of formation of several products, was followed by repeated
scanning of a portion of the spectrum throughout the irradia-
tion and the subsequent determination of concentration
changes as a function of time using the appropriate absorp-
tivities. The absorptivities of the olefins, formaldehyde, and
acetone were determined by multiple calibrations based on
manometric measurements. The absorptivity of meto-xylene
was determined by multiple calibrations based on analyses
made with a flame ionization detector. The absorptivity used
Volume 4, Number 1, January 1970 37
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ISOBUIENE OXIDATION
ACETONE FORMATION
J L
FORMALDEHYDE FORMATION
J \ I L
2 .4 .6 .8 10
INITIAL NITRIC OXIDE CONCENTRATION (PPMI
Figure 1. Nitric oxide inhibition of the atmospheric photooxidation
of 1 p.p.m. ethylene and 1 p.p.m. isobutene
for ozone was that reported by Hanst, Stephens, et al.,
(1961), while the absorptivity used for peroxyacetyl nitrate
was that reported by Stephens (1964). Concentrations are re-
ported in parts per million (p.p.m,) on a volume/volume
basis. The wavelengths, in microns, used for analysis were:
ethylene, 10.5; isobutene, 11.2; propylene, 11.0; trans-2-
butene, 10.4; weto-xylene, 13.0; formaldehyde, 3.6; acetone,
8.2; peroxyacetyl nitrate, 8.6; and ozone, 9.5.
Light intensity was measured by photolyzing very low con-
centrations of nitrogen dioxide in nitrogen, and is expressed
as the first-order rate constant for photolysis K^NOj). The
details and advantages of this method of light intensity
measurement in the experimental system have been described
previously (Tuesday, 1961). For all of the photooxidations in
the present investigation, the light intensity was equal to
0.29 min.-1.
Olefin Photooxidation Rate
The effect of the initial nitric oxide concentration on the
rate of ethylene and isobutene photooxidation was determined
at an olefin concentration of 1.0 p.p.m., and nitric oxide con-
centrations of 0.02-1.0 p.p.m. and 0.05-1.0 p.p.m., respec-
tively, with the results shown in Figure 1. For these olefins,
the photooxidation rate, was measured both by the rate of
olefin disappearance and the rate of formation of a major
carbonyl product. The rates are given in parts per billion per
minute (p.p.b. min."1), where the p.p.b. unit is determined on
a volume/volume basis. The rates of isobutene and ethylene
oxidation given are the average rates to the half-time for hy-
drocarbon photooxidation, i.e.,
average hydrocarbon oxidation rate
2tw
(1)
where (HQo is the initial hydrocarbon concentration and
/i/2 is the time necessary to reduce this concentration by one
half. The rates of acetone and formaldehyde formation are the
average rates during formation of 0.25 p.p.m. of these prod-
ucts, as defined by Eq. 2
average product formation rale =>
0.25
(2)
where tp is the time required to form 0.25 p.p.m. of the
product P.
For both ethylene and isobutene, initial increases in nitric
oxide concentration increase the olefin oxidation rate, but be-
cause of nitric oxide inhibition, higher concentrations decrease
this rate. The nitric oxide concentration required for the
maximum rate of ethylene oxidation is 0.1-0.2 p.p.m., in sub-
stantial agreement with the results of Altshuller and Cohen
(1964). Formaldehyde and acetone formation rates vary with
nitric oxide concentration in the same way as the correspond-
ing olefin oxidation rates. Since the carbonyl formation rates
and olefin oxidation rates are both average rates defined some-
what differently, the agreement between these rates is quite
satisfactory.
For the other olefins studied, /ra/w-2-butene and propylene,
the rate of olefin disappearance was the only measure of
olefin photooxidation rate used. The variation of this rate with
nitric oxide concentration is probably reflected in a corre-
sponding variation in the rate of formation of the appropriate
carbonyl product, in view of the agreement between these
two measures of olefin photooxidation found for ethylene and
isobutene
Nitric oxide inhibition of the atmospheric photooxidation
of ftww-2-butene has been investigated at olefin concentra-
tions of 1.0 and 2.0 p.p.m., with the results given in Figure
2. The photooxidation rate given is the average rate to the
half-time, as defined in Eq. 1. For both concentrations of
fra/w-2-butene, the photooxidation rate increases and then
.8 1.2 1.6 2.0 2.4
INITIAL NITRIC OXIDE CONCENTRATION (PPMI
J I L
28
Figure 2. Nitric oxide inhibition of the atmospheric photooxidation
of irans-2-butene
38 Environmental Science & Technology
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.2 .4 .6
INITIAL NITRIC OXIDE CONCENTRATION (PPM)
1.0
Figure 3. Nitric oxide inhibition of the atmospheric photooxidation
of propylene
decreases with increased nitric oxide concentration, as was
observed for ethylene and isobutene. For 2.0 p.p.m. trans-2-
butene, however, the maximum photooxidation rate occurs
at a nitric oxide concentration about twice that at which
the maximum rate occurs for 1.0 p.p.m. (rans-2-butene.
The maximum photooxidation rate occurs at a trans-
2-butene to nitric oxide ratio of about 5:1 for both
hydrocarbon concentrations. This result can be compared to a
ratio of about 2:1 for the photooxidation of 10 p.p.m.
trans-2-bulene (Tuesday, 1961). The explanation of this dif-
ference is not readily apparent. Altshuller (1967) found ap-
proximately the same ratio for the photooxidation of propy-
lene at propylene concentrations from 0.5-3 p.p.m., but at a
hydrocarbon concentration as high as 10 p.p.m., the ratio
may change.
The effect of initial nitric oxide concentration on the rate of
propylene photooxidation has been studied at olefin con-
centrations of 0.5, 1.0, and 2.0 p.p.m. and nitric oxide con-
centrations of 0.03-0.5, 0.07-1.0, and 0.05-1.0 p.p.m., re-
spectively. The results of this investigation are given in
Figure 3. The rate used is the average photooxidation rate to
the half-time, as defined in Eq. 1. For all three concentrations
of propylene, the photooxidation rate increases and then de-
creases with increased nitric oxide concentration, as was ob-
served for ethylene, isobutene, and /ra/w-2-butene. Again,
the nitric oxide concentration which results in the maximum
photooxidation rate for a given olefin concentration decreases
as the olefin concentration decreases. For each of the propylene
concentrations investigated, the maximum photooxidation
rate occurs at a nitric oxide concentration such that the ratio of
propylene to nitric oxide is about the same, i.e., 5-7. Altshuller,
Kopczynski, et al. (1967) found the time for 50% conversion
of 1.0 and 2.0 p.p.m. of propylene, in a static system, to
minimize at propylene .-nitrogen oxide ratios greater than or
equal to 4:1, and Romanovsky, Ingels, et al. (1967) found
the maximum rate of propylene disappearance to maximize at
ratios from (1-4) :1 for (0.5-2.0) p.p.m. of propylene. Our
results are consistent with those of Altshuller, but are in
disagreement with those of Romanovsky. This disagreement
may be due, in part, to the difference in rate measures used
in the two studies.
0.73 PPM _
0.34 PPM
J_
_L
_L
_L
0 .2 .4 .6 .8
INITIAL NITRIC OXIDE CONCENTRATION (PPM)
Figure 4. Nitric oxide inhibition of the atmospheric photooxidation of
meta-xylene
The qualitative effect of nitric oxide concentration on the
photooxidation rates of trans-2-butene, isobutene, propylene,
and ethylene is insensitive to the olefin used. The nitric oxide
concentration at which the maximum photooxidation rate
occurs varies with olefin concentration and is relatively in-
dependent of olefin type or reactivity, at a constant olefin con-
centration.
Meta-Xylene Photooxidation Rate
Nitric oxide inhibition of the atmospheric photooxidation
of meta-xylene has been studied at xylene concentrations of
0.34 and 0.73 p.p.m. The results of this study are given in
Figure 4. The xylene oxidation rates used are the average
rates to the half-time, as defined in Eq. 1. For both concen-
trations of we/a-xylene, the photooxidation rate increases and
then decreases with increased nitric oxide concentration.
The variation of xylene oxidation rate with nitric oxide con-
centration is somewhat less than the variation found for the
olefins. The nitric oxide concentration at which the maximum
xylene oxidation rate occurs is roughly proportional to the
xylene concentration. This is quite similar to the effect of olefin
concentration observed for both fra/w-2-butene and propylene.
For meta-xylene, however, the maximum oxidation rate ap-
parently occurs at a higher nitric oxide concentration for the
same concentration of hydrocarbon.
Ozone Formation Rate
Ozone is one of the products formed in the atmospheric
photooxidation of hydrocarbons (Haagen-Smit, Bradley,
et al., 1953). The effect of nitric oxide inhibition on the rate of
formation of this product has been determined for several
hydrocarbons and several hydrocarbon concentrations. The
results are given in Figures 5-7. The ozone formation rates
given are the average rates to one-half the maximum ozone
concentration formed, i.e.,
average ozone formation rate =
(3)
where (O3)mal is the maximum ozone concentration formed
in the photooxidation and ?i,2 is the time, from the beginning
of the irradiation, necessary to form one-half of this concen-
tration.
Volume 4, Number 1, January 1970 39
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O-
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of 2.7:1. The use of nitrogen dioxide rather than nitric oxide
(Tuesday, 1963) results in the maximum terminal ozone con-
centration from the photooxidation of tetramethylethylene
occurring at a higher hydrocarbon:nitrogen oxide ratio.
Comparison of the above literature results with the data
of this investigation show that maximum ozone yields occur,
in general, at higher hydrocarbon .-nitrogen oxide ratios in
our system. The effect is not consistent, however, since the
propylene results are in essential agreement with the literature,
while the ethylene and isobutene results do not agree. There
appears to be no explanation for these differences, although
the reaction chambers used in our study and in the literature
studies are rather different in composition. The methods of
analysis used are also different. In any event, there is no clear-
cut reason for differences of the magnitude noted, particularly
in the case of the ethylene system.
The effect of olefin concentration on the nitric oxide in-
hibition of ozone formation is shown in Figure 6. For all three
concentrations of propylene, the nitric oxide inhibition of the
ozone formation rate is similar to the inhibition of the propyl-
ene oxidation rate given previously in Figure 3. The maximum
olefin oxidation rate occurs at a nitric oxide concentration
such that the ratio of propylene:nitric oxide is about 5-7.
For each of the propylene concentrations investigated, the
maximum ozone formation rate occurs at a lower nitric oxide
concentration, so that in this case the ratio of propylene:
nitric oxide is about 10.
The effect of nitric oxide on the rate of ozone formation in
the photooxidation of meto-xylene was determined at meta-
xylene concentrations of 0.34 and 0.73 p.p.m. The results
shown in Figure 7 are quite similar to the results found for
the olefins studied. The ozone formation rate increases as the
nitric oxide concentration increases, reaches a maximum
value, and then decreases with further increases in nitric oxide.
The nitric oxide concentration at which this maximum value
occurs increases with /weto-xylene concentration. A similar
effect was noted previously for propylene. The maximum
ozone formation rates found for weta-xylene occur at lower
nitric oxide concentrations than do the maximum xylene
oxidation rates shown in Figure 4. In addition, the variation
of the ozone formation rate with nitric oxide is much greater
than the variation found for the xylene oxidation rate.
The nitric oxide inhibition of ozone formation shown in
Figures 5-7 can be partially attributed to the use of the rate
expression defined by Eq. 3. This rate definition was used,
since it most nearly represents the atmospheric formation of
ozone in photochemical smog. Since ozone does not ac-
cumulate until virtually all of the nitric oxide is oxidized, in-
creased concentrations of nitric oxide can result in a delay in
ozone appearance. It is interesting to note, however, that
nitric oxide inhibition is still observed when the ozone-de-
lay elfecl has been eliminated. The delay effect was eliminated
by subtracting the time at which ozone first appeared, to,
from the time required for formation of one half the maximum
ozone concentration, ti/i. The modified ozone formation rate
is then defined by Eq. 4 and the results are given in Table I.
modified ozone formation rate = —--""
Table I. Modified Ozone Formation Rate as a Function of
Initial Nitric Oxide Concentration in the Photooxidation of
1.0 p.p.m. Propy!ene°
(4)
2(/i/2 - to)
Nitric oxide inhibition is clearly evident, even when the ozone-
delay effect has been eliminated.
Effect o/ Added Nitrogen Dioxide
The effect of added nitrogen dioxide on the nitric oxide
inhibition of propylene photooxidation and ozone formation
was determined at a propylene concentration of 1.0 p.p.m.
(NO),,
(p.p.m.)
0.075
0.10
0.25
0 50
0.75
1.00
>„•>"
(min.)
70
54
82
142
209
270
to'
(mm.)
10
20
48
90
140
150
<03) ,
(p.p.m.)
C.24
0.23
0.30
0.35
0.28
0 18
Ozone
Rate''
(p.p.h.
inin."1)
2 0
3 4
4.4
3 4
2.1
0 85
" The reactions were carried out using the conditions given in the
experimental section.
6 The total time necessary for the formation of one half of the maxi-
mum ozone concentration.
" The time required for the onset of ozone formation.
d Calculated according to Eq. 4.
and an initial nitrogen dioxide concentration of 0.1 p.p.m.
The results are shown in Figure 8. For comparison, the results
obtained without added nitrogen dioxide are also included in
this figure.
Added nitrogen dioxide increases the rate of propylene
oxidation at the same initial nitric oxide concentration, ex-
cept at 0.5 p.p.m. A previous study (Tuesday, 1963) also in-
dicated that nitrogen dioxide acts as both a promoter and
inhibitor of olefin photooxidation. Nitrogen dioxide increases
the rate of ozone formation at very low nitric oxide concentra-
tions, but decreases this rate at higher nitric oxide concentra-
tions.
At the same total initial nitrogen oxide concentration, i.e.,
nitric oxide plus nitrogen dioxide, 0.1 p.p.m. of nitrogen
dioxide and 0.1 p.p.m. of nitric oxide affect the propylene
oxidation rate similarly at total nitrogen oxide concentrations
o NO INITIAL NITROGEN DIOXIDE
• 01 PPM INITIAL NITROGEN DIOXIDE H
0246
INITIAL NITRIC OXIDE CONCENTRATION IPPMI
Figure 8. Effect of added nitrogen dioxide on the photooxidation of
propylene
Volume 4, Number 1, January 1970 41
-------
less than 0.15 p.p.m. and greater than 0.6 p.p.m. For total
nitrogen oxide concentrations between 0.15 and 0.6 p.p.m.,
propylene oxidation is inhibited more by 0.1 p.p.m. of nitric
oxide than by 0.1 p.p.m. of nitrogen dioxide. However, in
terms of total initial nitrogen oxide concentration, 0.1 p.p.m.
of nitric oxide and 0.1 p.p.m. of nitrogen dioxide are equally
effective in inhibiting ozone formation throughout the con-
centration range investigated.
Peroxyacetyl Nitrate
Peroxyacetyl nitrate is another product of the atmospheric
photooxidation of many hydrocarbons (Stephens, Hanst,
et al., 1956). The effects of initial nitric oxide concentration
on the yield of this product from the photooxidation of 0.5,
1.0, and 2.0 p.p.m. of propylene are given in Figure 9. The
yields given are the concentrations of peroxyacetyl nitrate
formed after 2 hours of irradiation. The amount of peroxy-
acetyl nitrate formed varies with nitric oxide concentration in
the same way as the corresponding rates of propylene oxida-
tion and ozone formation (Figures 3 and 6).
The amount of peroxyacetyl nitrate formed increases and
then decreases with increased nitric oxide concentration, and
the nitric oxide concentration which gives the maximum
yield of peroxyacetyl nitrate increases with propylene con-
centration. Altshuller, Kopczynski, et al., (1967) found that the
peroxyacetyl nitrate yield after a two hour irradiation of 2.0
p.p.m. of propylene with various amounts of nitric oxide
maximized at approximately 0.7 p.p.m. of nitric oxide, whereas,
in our system, the maximum was attained at 0.3 p.p.m. As
discussed for the ozone results, there is no clear-cut reason
that can be given for this difference.
0.10 PPM TRANS-Z-BUfENE
0.10 PPM PROPYLENE
O.M PPM ISOBUTENE
O.li PPM CTKVlfNf
0.08 PPM MltA-XYUNt
246
INITIAl NITRIC OXIDE CONCENTRATION IPPMl
0
0 .2
INITIAL NITRIC OXIDE CONCENTRATION (PPM)
Figure 9. Peroxyacetyl nitrate from propylene photooxidation
42 Environmental Science & Technology
Figure 10. Nitric oxide inhibition of the atmospheric photooxidation
of a hydrocarbon mixture
Photooxidation of a Hydrocarbon Mixture
Nitric oxide inhibition of the photooxidation of a hydro-
carbon mixture was investigated using a mixture similar in
composition and concentration to those present in polluted
air. The hydrocarbon mixture was 0.1 p.p.m. of trans-2-
butene, 0.10 p.p.m. of propylene, 0.04 p.p.m. of isobutene,
0.25 p.p.m. of ethylene, and 0.08 p.p.m. of meta-xylene, for a
total carbon-atom concentration of 2.00 p.p.m.
The results of this investigation are given in Figure 10.
Nitric oxide inhibition of the photooxidation of this hydro-
carbon mixture was very similar to the inhibition found for
the photooxidation of the individual components given
previously in Figures 5,6, 7, and 9. Nitric oxide concentrations
higher than about 0.05 p.p.m. inhibited both the rate of ozone
formation and the amount of peroxyacetyl nitrate produced
after 2 hours' irradiation.
Discussion
Nitric oxide inhibition was observed in the atmospheric
photooxidation of all the hydrocarbons studied. This inhibi-
tion decreased the rate of hydrocarbon photooxidation, the
rate of ozone formation, the rate of carbonyl product forma-
tion in olefin photooxidation, and, at least for propylene, the
yield of peroxyacetyl nitrate.
As a result of nitric oxide inhibition, the rates of hydro-
carbon photooxidation and ozone formation are maximum
at a certain nitric oxide concentration. At lower or higher
nitric oxide concentrations, the rates of hydrocarbon photo-
oxidation and ozone formation decrease. For the two olefins
and the aromatic hydrocarbon studied, the nitric oxide con-
centration at which the maximum rates of hydrocarbon
photooxidation and ozone formation occur decreases as
hydrocarbon concentration decreases.
For the two olefins and the aromatic hydrocarbon studied,
decreases in hydrocarbon concentration decreased the rate of
hydrocarbon photooxidation, the rate of ozone formation,
and, at least for propylene, the amount of peroxyacetyl
nitrate formed.
Since nitric oxide inhibition was observed at concentra-
tions of hydrocarbon and nitric oxide actually found in the
atmosphere (Korth, Stahman, et al., 1964; Neligan, 1962),
-------
nitric oxide inhibition is apparently important in the photo-
chemistry of polluted atmospheres. If nitric oxide inhibition
is occurring, decreases in nitric oxide concentration at a con-
stant hydrocarbon concentration will increase the rates of
hydrocarbon photooxidation and ozone formation. Further-
more, decreases in hydrocarbon concentration at a constant
nitric oxide concentration will increase the amount of inhibi-
tion. As a result, the rates of hydrocarbon photooxidation and
ozone formation may decrease more than expected from the
hydrocarbon concentration decrease.
A recent paper by Schuck, Pitts, et al., (1966), of the Uni-
versity of California, Riverside, has verified that nitric oxide
inhibition is important in the polluted atmospheres found in
Los Angeles. Schuck, Pitts, et at., compared the 6-9 A.M.
atmospheric analysis made at the downtown station of the
Los Angeles Air Pollution Control District with the daily
maximum oxidant values recorded at the Pasadena Station,
and with smog incidence as defined by the Control District.
According to this definition, a "smoggy" day is a day when
moderate to severe eye irritation is reported, or a day on which
the visibility is less than 3 miles at a relative humidity less
than 60%. Schuck, Pitts, et al., found that both the percentage
of days resulting in smog and the atmospheric oxidant con-
centration were a maximum when the concentration of oxides
of nitrogen was about 0.15 p.p.m. Atmospheric nitrogen oxide
concentrations higher than this resulted in lower atmospheric
oxidant concentration and lower percentages of smoggy days,
indicating that nitric oxide inhibition was occurring in the
Los Angeles atmosphere.
Recent measurements made by the U.S. Public Health
Service (Korth, Stahman, et al., 1964) indicate that polluted
atmospheres may contain 3-8 p.p.m. of hydrocarbon, ex-
pressed as p.p.m. of carbon and 0.3-0.6 p.p.m. of nitrogen
oxide. If 6 p.p.m. of carbon and 0.4 p.p.m. of nitric oxide are
taken as average values, and propylene is assumed typical of
the hydrocarbons present in polluted atmospheres, then the
hydrocarbon oxidation rate in this atmosphere is the value
shown in Figure 3 for 2.0 p.p.m. of propylene and 0.4 p.p.m.
of nitric oxide. The effects of various reductions in hydro-
carbon and nitric oxide concentrations on the hydrocarbon
oxidation rate in the "typical" polluted atmosphere are shown
in Table II. All of the values used were taken from Figure
3.
This table indicates that, with no nitric oxide reduction,
the hydrocarbon oxidation rate is decreased more than ex-
pected by a given hydrocarbon reduction because of increased
nitric oxide inhibition. As shown in this table, reduction in
both nitric oxide and hydrocarbon decrease the hydrocarbon
oxidation rate less than hydrocarbon reduction alone. This
illustrates the observation made previously that decreases in
nitric oxide concentration decrease the amount of inhibition,
and, as a result, the hydrocarbon photooxidation rate in-
creases.
Table EL Hydrocarbon Rate Reduction"
Nitric oxide reduction (%) 0 25 50 75
0% hydrocarbon reduction .. —3 2 18
50% hydrocarbon reduction 64 58 52 56
75% hydrocarbon reduction 82 80 78 70
« Based on assumed current atmospheric levels of hydrocarbon =
6 p.p.m., of carbon - 2 p.p.m. of CiHj, nitric oxide = 0.4 p.p.m.
Schuck, Pitts, et al., have estimated fr< m the Los Angeles
atmospheric analyses mentioned previous ty the effect various
reductions in atmospheric levels of nitrogen oxides and hydro-
carbons would have on smog incidence, while recognizing
that their estimates are based on "a limited amount of data
along with many unproven assumptions.'" They concluded
that a "50% reduction in smog active hydrocarbons would
lead to a 50% reduction in the number of 'smoggy' days."
The results given in Table II, on the other hand, indicate that
a 50% reduction in hydrocarbon will decrease the hydro-
carbon oxidation rate by about 64%.
Schuck, Pitts, et al., also state that a 50% reduction in
oxides of nitrogen would not lead to a reduction in "smoggy"
days. The results given in Table I are in essential agreement
with this, since they indicate only a 2% decrease in hydro-
carbon oxidation rate with a 50% reduction in nitric oxide
concentration. For a 75% reduction in oxides of nitrogen,
Schuck, Pitts, et al., estimate a 20% reduction in smog in-
cidence, which is also in essential agreement with the 18%
reduction in hydrocarbon oxidation rate given in Table II.
This observation is contrary to an interpretation of atmo-
spheric and laboratory data by Hamming and Dickenson
(1966), see also Nicksic, Harkins, et al., (1966).
Mechanism
Free radical mechanisms have been proposed for both the
atmospheric photooxidation of olefins (Leighton, 1961;
Tuesday, 1961) and aromatics (Kopczynski, 1964). Since
nitric oxide and nitrogen dioxide are known inhibitors of free
radical reactions (Steacie, 1954), nitrogen oxide inhibition of
the atmospheric photooxidation of hydrocarbons is consistent
with these mechanisms.
Although the results of this study do not define the chemical
reactions responsible for nitric oxide inhibition, two pertinent
conclusions can be drawn from the data. The observation that
the maximum photooxidation and ozone formation rates
occur at a nitric oxide concentration approximately propor-
tional to the hydrocarbon concentration used suggests that
an inhibitory reaction approximately first-order in both
nitrogen oxide and hydrocarbon is important. As shown in
Figures 1, 2, and 3, the nitric oxide concentration necessary
for the maximum photooxidation rate is relatively insensitive
to olefin structure. This result implies that the electronic and
steric requirements of the inhibitory reaction(s) are similar to
those of the rate-determining step for photooxidation.
Acknowledgment
The authors acknowledge the valuable assistance of Jerome
Zemla in obtaining the experimental data and preparing the
figures.
Literature Cited
Altshuller, A. P., Cohen, I. R., Intern. J. Air Water Pollution
8, 611 (1964).
Altshuller, A. P., Kopczynski, S. L., Lonneman, W. A.,
Becker, T. L., Slater, R., ENVIRON. Sci. TECHNOL. 1, 899
(1967).
Glasson, W. A., Tuesday, C. S., J. Amer. Chem. Soc. 85, 2901
(1963).
Haagen-Smit, A. J., Fox, M. M., Ind. Eng. Chem. 48, 1484
(1956).
Haagen-Smit, A. J., Bradley, C. E., Fox, M. M., Ind. Eng.
Chem. 45, 2086 (1953).
Hamming, W. J., Dickenson, J. E., /. Air Pollution Control
Assoc. 16, 317 (1966).
Hanst, P. L., Stephens, E. R., Scott, W. E., Doerr, R. C.,
Anal. Chem. 33,1113 (1961).
Volume 4, Number 1, January 1970 43
-------
Kopczynski, S. L., Intern. J. Air Water Pollution 8, 107
(1964).
Korth, M. W., Stahman, R. C, Rose, A. H., Jr., J. Air Pollu-
tion Control Assoc. 14,168 (1964).
Leighton, P. A., "Photochemistry of Air Pollution," p. 269,
Academic Press, New York, 1961.
Neligan, R. E., Arch. Environ. Health 5, 581 (1962).
Nicksic, S. W., Harkins, J., Painter, L. J., Intern. J. Air Water
Pollution 10,15(1966).
Romanovsky, J. C., Ingels, R. M., Gordon, R. J., J. Air
Pollution Control Assoc. 17,454 (1967).
Schuck, E. A., Pitts, J. N., Jr., Wan, J. K. S., Intern. J. Air
Water Pollution 10, 689 (1966).
Steacie, E. W. R., "Atomic and Free Radical Reactions,"
Vol. I, p. 56, Reinhold, New York, 1954.
Stephens, E. R., Anal. Chem. 36,928 (1964).
Stephens, E. R., Hanst, P. L., Doerr, R. C., Scott, W. E.,
Ind. Eng. Chem. 48,1498 (1956).
Tuesday, C. S., Arch. Environ. Health!, 72(1963).
Tuesday, C. S., "Chemical Reactions in the Lower and Upper
Atmosphere," p. 15, R. D. Cadle, Ed., Interscicnce, New
York, 1961.
Received for review November 29, 1969. Accepted July 31,
1969. Paper was presented in part at the 148th Meeting, ACS,
Chicago, III., Sept., 1964.
44 Environmental Science & Technology
-------
Ambient Air Quality and Automotive Emission Control
Wayne A. Daniel and Jon M. Heuss
General Motors Corporation, Warren, Michigan
This paper is concerned with uncertainties involved in projecting ambient air quality.
Ambient air quality was projected by assuming a linear dependence on estimated
future emissions. Future automotive emissions were estimated by a method rec-
ommended by EPA. Projections were made for the locations reported to have
the highest ambient air concentrations of each pollutant; Chicago for carbon
monoxide and the California South Coast Air Basin for hydrocarbon and oxidant.
The sensitivity of the projections to several input parameters was determined.
The uncertainty in projection of air quality due to the use of a maximum, once-
per-year concentration is large. For example, the reduction in total CO emissions
in Chicago in 1975, necessary to meet the air quality standard, was as high as 68%
or as low as 26%, depending on whether the historic high, 8 hr average concen-
tration of 44 ppm or the 1970 maximum of 21 ppm was used. The effects of
uncertainties in growth rates and fraction of emissions attributed to the automobile
were also sizeable. Differences in automotive growth rate had a large near-term
effect on projected concentrations, while differences in nonautomotive growth rate
or fraction of emissions attributed to the automobile had a large long-term effect.
The effect of 1 975 interim automotive emission standards on projected air quality
was negligible when compared with projected air quality based on the previous
Federal automotive emission standards for 1975.
Many projections of future emissions of pollutants have been
made. In this paper we have considered some uncertainties
associated with projections of ambient air quality made with
the proportional model, which assumes that emissions and air
quality are linearly related. The assumption of a linear
relation was made by the California Department of Public
Health1 in deriving the first automotive emission standards
and by Barth2 in determining automotive emission goals for
1980. More recently Trijonis3 and Cantwell, et al.,* have
questioned the assumption of a linear relation between emis-
sions and ambient air concentrations. At present, however,
the linear relationship is accepted for use in the development
of control strategies for attaining the National Air Quality
Standards.
Kircher and Armstrong5 recently published methods for
estimating area-wide emissions attributed to gasoline powered
vehicles. The methods were developed "specifically for use by
state and local air pollution control agencies in preparation of
transportation control measures and evaluation of alterna-
tives." Consequently, the present study used the Kircher-
Armstrong method, with some modification, to determine the
sensitivity of projections of ambient air quality to: (1)
variations in historical, once-per-year, maximum ambient
concentrations; (2) estimates of the growth rates of auto-
motive and nonautomotive sources and of the portion of the
total emission attributed to the automobile; and (3) the 1975,
interim automotive exhaust emission standards.
Carbon monoxide (CO) ambient air concentrations were
projected for Chicago, and hydrocarbon and oxidant ambient
air concentrations were projected for the California South
Coast Air Basin. These localities were chosen since they
were considered by Barth2 to be the worst situations observed
in the U. S. for these pollutants.
Total oxides of nitrogen (NO,) and nitrogen dioxide (N02)
ambient air concentrations were not projected because of
uncertainties concerning future automotive emission stan-
dards, present N02 concentrations, and the timetable for
implementing stationary source controls.
Reprinted from APCA JOURNAL, Vol. 24, No. 9, September 1974
-------
Analysis Technique
In all cases a linear relation between ambient air concentra-
tion and man related emissions was assumed:
Ambient concentration — Background concentration =
K (Automotive emission + Nonautomotive emission)
The background concentration is that portion of the ambient
concentration attributable to natural, rather than man
related, emission sources. K is a proportionality constant
which involves local meteorological as well as source distribu-
tion factors. In this simplified model, A' was considered
constant for a specific geographical area and for the time
frame involved. Thus, it was assumed that neither the
emission source distribution nor meteorological factors
changed from the reference year to a future year. It was
not necessary to determine K, since ambient concentrations
for a future year were projected from a reference year. The
projected concentrations were obtained by equating the ratio
of future to reference year concentrations with the ratio of
future to reference year emissions.
Automotive emission for a given calendar year was ex-
pressed as an average car emission. This average car
emission was calculated by the procedure given by Kircher
and Armstrong.6 The low mileage emission rates for pre-
1975 automobiles, the weighted, annual travel of the various
model year automobiles in a given calendar year, and the
deterioration factors for pre-1975 automobiles given by
Kircher and Armstrong were used.
The exhaust hydrocarbon emission rates presented by
Kircher and Armstrong for pre-control automobiles, 1965
and earlier in California, are considerably lower than the
emission rates previously used by EPA for these early model
automobiles. As a consequence, the calculated percent
reduction in automotive emissions and projected reduction in
ambient hydrocarbon concentration, due to subsequent
automotive emission control, are not as large as they would
have been if the previous values were used.
We did not use the emission rates and deterioration factors,
for post-1974 automobiles, given by Kircher and Armstrong,
because we believed their estimated deterioration factors
were unrealistic. Instead, low mileage, on the road, average
emission rates for 1975 and later model year automobiles were
estimated on the basis of the Federal emission standards
and the deterioration factors reported by Kircher and Arm-
strong for 1970-74 model automobiles. It was assumed that
the average emission level, for a given model year, would not
exceed the Federal emission standard level before the end of
5 years. Consequently, new car, low mileage hydrocarbon
and carbon monoxide emission levels were 85.5 and 69.5%
of the 1975 Federal emission standard levels respectively.
Projected automotive emissions were obtained by multiply-
ing the average car emission, calculated for a particular year,
by a growth factor, relative to the reference year.
Nonautomotive reference year emission was obtained by
proportioning the total annual emission between automotive
and nonautomotive sources, using emission inventories for
the specific geographic locations. Projected nonautomotive
emissions were obtained by multiplying the reference year
nonautomotive emission by a growth factor.
Reference year parameter values given in Table I were used
for base line projections of ambient air concentrations and for
determining the effects of the 1975 interim automotive ex-
haust emission standards. The additional values used in the
parameter studies are noted in the descriptions of those
studies. For the parameter studies, the automotive exhaust
emission standards given in Table II were used. These are
the standards specified at this time, May 1973.
Two criteria were considered in evaluating the significance
of the uncertainty, or lack of precision, in projected ambient
air quality: (1) the percent reduction in total emissions
necessary to meet the air quality standard by 1975, the Clean
Air Act deadline, and (2) the range, in ppm, of the projected
ambient air quality in 1385. Consequently, both near and
long-term effects of variations of the input parameters on
projected air quality were examined.
To facilitate making ambient air quality projections for a
large number of different input conditions and for many
future years, the calculation.-; were carried out on a computer.
A copy of the computer program is available upon request
from the authors.
Projected Carbon Monoxide Ambient Concentration
The historic maximum, 8 hr average CO concentration
reported for Chicago, 44 ppm, was used as the reference year
value for the projection shown in Figure 1. Other input
parameter values and automotive exhaust emission standards
were those given in Tables I and II. Eight hour average
ambient CO concentrations, which could result in blood
carboxyhemoglobin (COHb) levels of 5 and 23^% in non-
smokers (28 to 32 ppm and 12 to 15 ppm), NAPCA;6 and the
National Ambient Air Quality Standard (9 ppm) are marked
on the figure for reference purposes. Two histograms are
also shown in Figure 1. One histogram is plotted for 1966 and
one for 1981. These histograms show the expected number
of 8 hr intervals having CO concentrations within each 1 ppm
increment. The histograms were obtained by assuming a
lognormal distribution of concentration;13 consecutive, non-
overlapping intervals; and that the distribution could be
scaled between years. The histograms emphasize the fact
that the projected curve represents the maximum, once-per-
year concentration and that most 8 hr average concentra-
tions, and hence exposures, are much lower, even at this worst
case, downtown site. For instance, in 1966, the average 8 hr
average concentration was about 13 ppm, and in 1981, the
average was projected to be between 2 and 3 ppm.
A margin of safety in protecting susceptible individuals
from the first effects of CO was included in setting the ambient
air quality standard of 9 ppm. The first effects of CO on
susceptible individuals may occur between ftA and 5%
COHb.14 Preventing ambient CO concentrations from
reaching 9 ppm more than once-per-year introduces an addi-
tional large margin of safety. This additional margin of
safety has often been overlooked.
Table 1. Reference year parameter values.
Reference year
Concentration (ppm)
Background (ppm)
Fraction attributed
to automobile
Automobile growth rate
(not compounded)
Nonautomotive growth
(not compounded)
Carbon
monoxide
1966"
44."
O.lb
0.99*
l%d
0
Hydrocarbon
1967
5.3"
0.1"
0.894'
4.4%"
Oh
Oxidant
1970
0.67«
0'
0.894'
4.4%*
Oh
* The 44 ppm 8 hr average CO concentration was recorded in December
1965, but is given for 1966 by NAPCA.«
b Seiler and Junge.7
"•In a downtown area, essentially all of the CO is due to automobile.
d Most ambient CO is due to local sources,' and traffic density in down-
town areas has a low growth rate."
e Barth,« ppm carbon.
'South Coast Implementation Plan."
a California Air Resource Board "
* RECAT."
Table II. Automotive exhaust emission standards.
(grams per mile—1975 Federal Test Procedure)
CO'
HCb
1974C
1975
1976d
28.2
15.0
3.4
3.03
0.90
0.41
• In all states except California.
b For California only.
<• Pre 1975 emission rates same as given by Kircher and Armstrong «
d Post 1976 emission standards same as 1976 values.
850
Journal of the Air Pollution Control Association
-------
Number of
c intervals
3 100 0
1975 1980
Year
1985
1990
Figure 1. Projected ambient 8 hour average carbon monoxide concen-
trations and two representative histograms.
The maximum 8 hr average CO concentrations reported
for Chicago for each year from 1962 through 1971 are plotted
in Figure 2. Projected maximum, 8 hr average concentra-
tions are also shown, using each of the reported values as the
reference year value. Ambient CO concentrations, projected
from reference years 1962-1970, are considerably different
from the comparable CO concentrations reported for the same
time period. Variations in meteorology in these years could
possibly account for the differences, although systematic
errors in measurement have also been implicated.16 The
reduction in total emissions in 1975, necessary to meet the air
quality standard, may be as high as 68% or as low as 26%,
depending on whether the projected, 1975, ambient air quality
is based on the 1966 or the 1970 maximum, eight-hour-average
carbon monoxide concentration. Corresponding implementa-
tion plans would be drastically different. The range in
projected ambient carbon monoxide concentrations in 1985,
because of different reference year concentrations, is only 2
ppm. After about 1981, reference year concentration differ-
ences had essentially no effect on the projected concentrations.
The effects of differences in automotive growth rate and in
the fraction of the total, reference-year emissions attributed
to the automobile on the projected CO concentrations are
shown in Figure 3. Growth rates of 0 and 5%, not com-
pounded, and fractions attributed to the automobile of 0.90
and 0.99 were considered. These ranges were thought to
encompass the actual values and to be sufficiently wide to
illustrate possible variations in the projected values, which
might be attributed to uncertainties in estimates of either
parameter. Differences in automotive growth rate (com-
pare the two dotted lines, or the two dashed lines) had a
larger near-term than long-term effect, and differences in
fraction of emissions attributed to the automobile (compare
top dotted line with top dashed line, or bottom dotted line
with bottom dashed line) had a larger long-term than near-
term effect on projected, ambient CO concentrations. The
reduction in total emissions in 1975, necessary to meet the
air quality standard, was either 76 or 66%, depending on
automotive growth rate, and was essentially unaffected by the
differences in the portion of the reference year emissions at-
tributed to the automobile. The range in projected ambient
CO concentration in 1985, because of the different automotive
growth rates, is 3.6 ppm, and because of the different frac-
tions of the reference year emissions attributed to the auto-
mobile is 2.4 ppm. The combined range is 6 ppm, which is
significant when compared with th< CO air quality standard
of 9 ppm.
The effect of growth rate of nono itomotive CO emissions is
shown in Figure 4. I aerpai-'im1, .'me dwreasing growth rates of
4%/yr, not compounded, w?r(> s"leck-d as being reasonable
estimates. If 99% of the CO omission in 1966 were attributed
to the automobile, the growth rate in nonnutomotive soiiws
would have very little
I«'-HT, u
f 90% was
assumed for the projections shown in '''inure-!. A.-, would Iw.
expected, differences in projected r.ml ieut, iiir roiu'.eni.rntu/ii",
due to differences in nonautoinotive emission growth rate.
increased with time. With Ihese nonfmtoniotive emission
growth rates, about, the same total erri'ssion reduction in 1975,
68 and 72%, would be required to meet the air quality stan-
dard. The range in projected 1985 ambient CO concentra-
tions, because of different growth rates of nonautomotive
emissions, is 6.6 ppm.
The total range in projected 1985 ambient concentrations,
combining the results shown in Figures 2 - i is 9 ppm. Thut--,
there are significant differences in the projected eonoentia-
tions associated with reasonable estimates for the input
parameters.
The effect of the one year interim, 1975 automotive ex-
haust emission standard on projected ambient CO concentra-
tions is shown in Figure 5. Changing the 1975 exhaust
emission standard from 3.4 to 15.0 gpm, increased the pro-
jected 1980 ambient CO concentration from 10.9 to 11.7 ppm,
a negligible increase. However, the air quality should still
be below the ambient concentration which could result in a
COHb level of 21A%.
It should be emphasized that the projected, ambient CO
concentration curves presented in Figures 1-5 represent a
possible, once-per-year occurrence at what is thought to be
1965
1970 1975 1980 1985
Year
1990
Figure 2. Maximum 8 hi average carbon monoxide
concentrations in Chicago.
T~> 90% attributed
to automobile
__________ X.'j-X >.-.
1965 1970 1975 1980 1985 1990
Year
Figure 3. Effects of automotive growth rate and portion
of reference year emissions attributed to the automobile
on projected, ambient carbon monoxide concentration.
September 1974 Volume 24, No. 9
851
-------
the worst location in the U. S. At all other times and at all
other places, the projected, 8 hr average CO concentrations
would be lower.
Projected Nonmethane Hydrocarbon
Ambient Concentration
Projected ambient hydrocarbon concentration.-* are com-
pared in Figure f> with the National Air Quality Standard of
0.24 ppin (',, ouee-per-yetir, (> 0 A.M. average noninethane
hydrocarbon concentration. Projections obtained with and
without the 1975 interim exhaust hydrocarbon omission
standard arc also shown. In addition, ambient nonmethane
hydrocarbon concentrations were; projected assuming zero
new car exhaust hydrocarbon emissions after 1975 to indicate
a possible lower limit. It should be noted that in projecting
nonmethane hydrocarbon concentrations based on projected
total hydrocarbon emissions, it was assumed that the ratio
of nonmethane to total hydrocarbon remained constant.
Crankcaso and evaporative automotive hydrocarbon emis-
sions, as given by Kircher and Armstrong, were also included
as part of the emissions.
The projected nonmethane hydrocarbon concentration,
shown in Figure 6 for the current emission standards, de-
creased about 63% from 1970 to 1980, as a result of a decrease
in total automotive emissions of about 72%. Changing the
1975 exhaust hydrocarbon standard frpm 0.41 gpm to 0.9
gpm, increased the projected ambient hydrocarbon con-
centration in 1980 from 1.80 ppm to 1.82 ppm, an increase of
about 1%. If new car exhaust hydrocarbon emissions were
zero after 1975, the projected ambient hydrocarbon concentra-
tion iu 1980 would be 1.72 ppm, about 5% lower than the
projected concentration obtained with the current exhaust
emission standards.
540
:rr- Nonautomotive emission growth rate
Air quality standard ^-.-
o—.-— r"'Contribution of nonautomotive
Ti sources"
1965 1970
1975 1980
Year
1985 1990
Figure 4. Effect of nonautomotive emission growth rate
on projected, ambient carbon monoxide concentration.
50
540
l
•§,!
5 <
|!
i
*30
520
§10
\ With 1975 interim
\ /standard
\/
Air quality standard
--V
1965
1970
1975 1980
Year
1985 1990
Figure 5. Effect of automotive interim emission stan-
dard on projected, ambient carbon monoxide concen-
tration.
It is apparent from the results shown in Figure 6, that no,
new car exhaust hydrocarbon standard, including zero emis-
sions after 1975, would result in meeting the National Ambient
Air Quality Standard for nonmethane hydrocarbons. Con-
siderable reduction in nonautomotive hydrocarbon emissions
would also be required if the standard is to be met. In fact,
the background nonmcthtme hydroetirlion concentration in
Ix>s Angeles may be higher thini the hydrocarbon air ((utility
standard.1*'"1 This liydrnrnrhoii standard, however, may
not be enforced as long as the osidiint. .slnndiiril is met."
Oxidant ambient air ((Utility in the South Coast, Air MiiMin is
considered in the next section.
Projected Oxidant Ambient Concentration
The maximum, one-hour-average oxidant concentrations in
the California South Coast Air Basin for each year from 1964
through 1972 are plotted in Figure 7. Projected maximum,
1 hr average concentrations are also shown, using each of the
measured values as the reference year value.
The projections were obtained by assuming a linear rela-
tion between reactive hydrocarbon emissions and oxidant
concentration. This is the same relation used in the State of
California, South Coast Air Basin Implementation Plan.10
It was also assumed that the ratio of reactive to total hydro-
carbons remained constant for all emission sources. Parame-
ter values and automotive hydrocarbon emission standards
used for the projections are given in Tables I and II.
Ambient oxidant concentrations, projected from reference
years 1964-1971, are quite different from the comparable
oxidant concentrations reported for the same time period.
The maximum, once-per-year values were likely determined
by seldom repeated circumstances, whereas the projections
were based on average emissions throughout the air basin.
As a consequence, estimated reductions of total emission in
1975, necessary to meet the air quality standard of O.C8
ppm, varied between 77 and 83%, depending on which ref-
erence year was used for the projection. Although the differ-
ence appears small, it is significant because emission control
becomes increasingly difficult as the degree of control ap-
proaches 100%.
In all cases, the projected oxidant concentrations exceed
the air quality standard at this worst location in the Nation.
The range in projected 1985 ambient oxidant concentrations,
because of different reference year concentrations, is only
-E 5
So fc
2 D.
|!4
»l
!i
(0 £ Q
fl) O O
>,<->
M
E 1
X
\
\
With 1975 interim standard
Zero automotive exhaust '\\
emission after 1975 — \1>
Contribution of nonautomotive sources
1965
1970
1975 1980
Year
1985
1990
Figure 6. Effect of automotive interim emission stan-
dard on projected, ambient nonmethane hydrocarbon
concentration.
852
Journal of the Air Pollution Control Association
-------
*B— K
m = .b
SE
^•3
3 2
II.2
-_h\t quality standard
Contribution of nonautomotive sources
1965 1970 1975 1980 1985 1990
Year
Figure 7. Maximum 1 hr average oxidant concentrations
in the South Coast Air Basin.
&
C
i
.14
-12
£•£
,,.»
e'S.
1108
^ §.06
|8
.02
Contribution of nonautomotive sources
1965 1970 1975 1980 1985 1990
Year
Figure 8. Yearly means of daily maximum, 1 hr average
oxidant concentrations in the South Coast Air Basin.
0.025 ppm. The effect of different reference year concentra-
tions on projected ambient concentrations diminishes with
time.
Yearly averages of daily-maximum, one-hour-average
oxidant concentrations for 11 stations in the South Coast Air
Basin, Air Resources Board,11 are plotted in Figure 8. Pro-
jected concentrations are also shown. The agreement be-
tween projected concentrations and the measured concentra-
tions, which were averages over time and area, is much better
than the agreement shown in Figure 7, where the measured
concentrations were maximum, once-per-year values. In
Figure 8, the variation about the median value projected for
1975 is ±7.3%, whereas in Figure 7 the comparable variation
is ±16.3%, a two-fold difference. As would be expected,
there is more precision in projected average, daily maximum
oxidant concentrations than in projected maximum, once-
per-year oxidant concentrations.
The effects of differences in automotive growth rate and
in the fraction of the total, reference year concentration
attributed to the automobile on the projected oxidant con-
centration are shown in Figure 9. Growth rates of 0
and 5%/yr, not compounded, and fractions attributed to the
automobile of 0.8 and 1.0 were considered. The assumption
that all of the ambient oxidant concentration is attributable
to the automobile results in the same projection as an assump-
tion that nonautomotive emissions have the same growth and
are subjected to the same control a? automotive emissions.
After about the first three yeari-, the absolute difference in
the projected oxidant concentration associated with differ-
ences in automotive omission growth (compare the two dotted
lines or the two dashed lines) was .-.bout constant. On the
other hand, projected differences, due to differences in the
fraction of total emissions attributed to the autmobilc (com-
pare top dotted line with top dashed line or bottom dotted
line with bottom dashed line) increased with time. Even
though automotive emissions were Mfniific.nrtly reduced, the
constant, nonautomotive emissions, :n the case where 0.8
of the 1970 emissions were attributed to the automobile,
limited the possible reduction in ambient oxidant concentra-
tion. The reduction in total emissions in 1975, necessary to
meet the air quality standard, would be either 78%, if all
emissions were due to the automobile and the automobile
growth were zero; or would be 84%, if only 0.8 of the emission
were due to the automobile and the automobile growth were
5%/yr. The range in projected ambient oxidant concentra-
tion in 1985, because of the different automotive growth
rates, is 0.12 ppm, and because of the different fractions of the
reference year emissions attributed to the automobile, is
0.03 ppm. The combined range is 0.15 ppm, which is almost
twice the oxidant are quality standard of 0.08 ppm.
The effect of growth rate of nonautomotive, reactive-
hydrocarbon emissions is shown in Figure 10. Both increas-
ing and decreasing growth rates of 4%/yr, not compounded,
were used. Differences in projected ambient oxidant con-
centrations, due to differences in nonautomotive emission
growth, increased with time. About the same total emission
reduction in 1975, 83 and 84%, would be required to meet the
air quality standard for either growth-rate projection. How-
ever, the 4%/yr increased in nonautomotive emission caused
the projected oxidant concentration to exceed the air quality
standard even if there were no automotive emissions. The
range in projected 1985 ambient oxidant concentrations, be-
cause of different growth rates of nonautomotive emissions,
is 0.08 ppm.
The total range in projected 1985 ambient concentrations,
combining the results shown in Figures 7, 9 and 10, is 0.15
ppm. Apparently, considerable reductions in both automo-
tive and nonautomotive hydrocarbon emissions will be re-
quired to meet the National Ambient Air Quality Standard of
0.08 ppm, once-per-year, 1 hr average oxidant concentration
in the South Coast Air Basin. However, this area is recog-
nized as the worst in the Nation for photochemical smog.
The situation should be better everywhere else.
Discussion and Conclusions
The ambient air quality projections presented in this paper
are obviously only as good as the assumptions involved in the
calculation method and the accuracy of the input data. A
simplified model of the pollutant emission-ambient concentra-
tion problem was used. However, similar models have been
and are being used by various regulatory agencies. We were
necessarily restricted to using available data on ambient
concentrations, emission rates, etc. By including ranges,
which were believed to encompass actual values of the parame-
ters, it was possible to determine variations in the projected
values which might be attributed to uncertainties in the input
data.
There are additional uncertainties involved in projecting
ambient oxidant concentration. Oxidant or ozone is the
product of a complex series of chemical reactions between
hydrocarbons and oxides of nitrogen in the atmosphere.
The assumption being used in implementation plans, that
oxidant concentrations are proportional to reactive hydro-
carbon emissions, is a simplistic approach to a complex prob-
lem. Merz, et al.,ls Dimitriades,19 and Trijonis* have pro-
posed other relationships between hydrocarbon, oxides of
nitrogen and oxidant. The degree of control of NOZ emis-
sions, the contribution of low reactivity hydrocarbon emis-
September 1974 Volume 24, No. 9
853
-------
sions to oxidant formation, and changes in the hydrocarbon
composition in the South (''oast Basin with time, are all
expected to affect oxid:int production.
Considerably different ambient air quality projections
were obtained with the variations in the input parameters
considered in this study. Reference year ambient air con-
centrations and automotive growth rate had a greater near-
term effect on projected air quality than in the long-term, and
the portion of the emissions attributed to the automobile
and nonautomotive emission growth had a greater long-term
effect on projected air quality than in the near-term.
Implementation plans for meeting the air quality standard
in 1975 could be drastically different, depending on the values
of the input parameters used for projecting anticipated air
quality. It is therefore desirable to estimate the input data
for projecting ambient air quality with extreme care. Some
of the lack of precision, which results from differences in
reference year, ambient concentrations, would be eliminated
by using average concentration measurements rather than a
single, once-per-year, maximum value. The average con-
centration measurements could be either an average of
maximum values obtained at many sampling stations or
possibly an average of the few highest measurements obtained
at a single station.
The granting of interim exhaust emissions standards for
1975 model automobiles, as opposed to maintaining the
previous Federal automotive emission standards for 1975,
was projected to have essentially no effect on the ambient air
quality.
Ambient air quality projections are necessary for establish-
ing local implementation plans, and are useful in determining
National pollutant emission standards. We propose that
the projections be made with the most accurate estimates of
the input parameters, rather than possible extreme values.
A margin of safety in protecting human health was included
in establishing the National Ambient Air Quality Standard
concentrations, and an additional large safety factor was
achieved by imposing the once-per-year criterion. Adding
still other safety factors, by using extreme values for project-
ing ambient concentrations, appears unnecessary.
References
1. State of California Department of Public Health, "Technical
Report of California Standards for Ambient Air Quality and
Motor Vehicle Exhaust," Berkeley, Calif., 1960.
2. D. S. Barth, "Federal motor vehicle emission goals for CO,
HC, and NO* based on desired air quality levels," J. Air
Poll. Control Assoc., 20: 519 (1970).
3. J. C. Trijonis, "An Economic Air Pollution Control Model-
Application Photochemical Smog in Los Angeles County in
1975," Ph.D. Thesis, California Institute of Technology,
Pasadena, Calif., 1972.
4. E. N. Cantwell, W. E. Bettoney, and J. M. Pierrard, "A
Total Vehicle Emission Control System," presented at
American Petroleum Institute Division of Refining 38th
Midyear Meeting, Philadelphia, Pa., May 1973.
5. D. S. Kircher and D. P. Armstrong, "An Interim Report on
Motor Vehicle Emission Estimation," Office of Air Quality
Planning and Standards, Environmental Protection Agency,
revised Jan. 1973.
6. "Air Quality Criteria for Carbon Monoxide," NAPCA Publ.
No. AP-62, March 1970.
7. W. Seiler and C. Junge, "Carbon monoxide in the atmo-
sphere," /. Gcophys Res., 75 : 2217 (1970).
8. W. B. Johnson, W. F. Dabberdt, F. L. Ludwing, and R. J.
Allen, "Field Study for Initial Evaluation of an Urban
Diffusion Model for Carbon Monoxide," Comprehensive
Report, Coordinating Research Council and Environmental
Protection Agency, Contract CAPA-3-68 (1-69), Stanford
Research Institute, Menlo Park, Calif., 1971.
9. W. Ott, J. F. Clarke, and G. Ozolins, "Calculating Future
Carbon Monoxide Emissions and Concentrations from Urban
Traffic Data," NAPCA Publ. No. 999-AP-41, 1967.
10. State of California South Coast Basin Implementation Plan,
1971.
11. California Air Resources Board, "Air Quality and Emissions
1963-1970," Nov. 1971.
12. Cumulative Regulatory Effects on the Cost of Automotive
Transportation-RECAT, prepared for the Office of Science
and Technology, 1972.
.o
.7
"c
lc.6
Qfl ~
SI
SS 5
»- Q.
0 ">
1i> 2. 4
0 c
p.2
p. 3
.fc c
ra y
Eg ,
>," ^
n>
,1
0
1 1 1
.
"•:«. &% growth rate
\\\
\\v
Zeio growth rat*''., •.
\\V.
\V \
\ ''NX
\ 'A -.
%
100% attributed^ — v "X
to automobile \\ \
\
T
,30% attributed
to automobile
Contribution of nonautomotive sources
Air quality standard \ ""x^
1 i 1 .__
1
1965 1970
1975 1980
Year
1985 1990
Figure 9. Effects of automotive growth rate and portion
of reference year emissions attributed to the automobile
on projected ambient oxidant concentration.
ra
!i-6
D0=
2 E
§S.5
5.l
E*-
TO 3
is'
X U
as c
poo
V o -^
3
.1 -
1 1
\
-
-
-Air quality standard
— i 1 1
,\ Nonautomotive growth rate
\\ ^Increase 4% per year
'•.• -Decrease 4% per year
'•,/ (not compounded) -
\\
\\
'•. \
\ \
~N,
. —* - r.
Contribution of nonautomotive sources -
1965 1970
1975 1980
Year
1985 1990
Figure 10. Effect of nonautomotive emission growth
rate on projected, ambient oxidant concentration.
13. R. I. Larsen, "A new mathematical model of air pollutant
concentration averaging time and frequency," J. Air Poll.
Control Assoc., 19: 24 (1869).
14. J. M. Heuss, G. J. Nebel, and J. M. Colucci, "National air
in Medical Aspects of Air Pollution, Society of Automotive
Engineers, 1971.
16. A. P. Altshuller, W. A. Lonneman, F. D. Sutterfield, and
S. L. Kopczynski, "Hydrocarbon composition of the atmo-
sphere of the Los Angeles Basin—1967," Environ. Sci. Tech-
nol.5: 1009(1971).
17. Federal Register, 36: 81H6 (1971).
18. P. H. Merz, L. J. Painter, and P. R. Ryason, "Aerometric
data analysis-time series analysis and forecast and an at-
mospheric smog diagram," Atmos. Environ., 6: 319 (1972).
19. B. Dimitriades, "Effect of hydrocarbon and nitrogen oxides
on photochemical smog formation," Env. Sci. Technol., 6:
253 (1972).
Mr. Daniel is in the Fuels and Lubricants Department
and Mr. Heuss is in the Environmental Science Depart-
ment, Research Laboratories, General Motors Corpora-
tion, General Motors Technical Center, Warren, Mich.
48090. This paper was presented as Paper No. 73-72 at
the 66th Annual Meeting of APCA at Chicago in June 1973.
854
Journal of the Air Pollution Control Association
-------
D. MR. LOUIS LOMBARDO
PUBLIC INTEREST CAMPAIGN
-------
Public Interest Campaigns
9711 MacArthur Boulevard
— — — ,*., Louis V Lombardo
Advisory Council BetheSQa, Md. ZOO.J4 President
John Esponto, Esq (301)365-0412 Dirnru.rs
Chairman
Clnien, ,-M Dillow I
Edward Ayres
_ John ckpomto, LMJ
Philip Boraano. Esq. ,
. _ LmiuV Lomhairlo
Carl H. S.rgman
. . ~ .. .>n H.rburl S Lunentitld
Jo«l BuxbMim, M.D.
R ogar Ch.llop, M.D. Munan \
Clarence M. D.tlow. Esq. R """" '
Albert Fnttch. Ph.D. February 12, 1915
Sem Lov.
William H. Rodgery Jt, Esq
Edmund Rothfchild, M.D.
J.f< St.ntbury
James Sultlvan. Ph.D.
Robert 0. Vaughn, Esq
Dr. Herbert A. Wiser
Deputy Assistant Administrator
Environmental Protection Agency
Washington, D.'C. 20460
Dear Dr. Wiser:
This is to request the following questions be sent, Special Delivery,
return receipt requested, to each of the speakers at this seminar for res-
ponse by February 21 in order that the record may be completed in
enough time to assist the Administrator in his decision due March 3,
1975.
1. Given the requirements of the Clean Air Act that ambient air
quality standards should be set to protect the health of all
susceptible population groups -- the ill, the elderly, the very
young, etc. -- outside of artificial environments, and set with
an adequate margin of safety:, Do you believe the ambient air
quality standards are too stringent, not stringent enough or just
right? Please answer for HC, CO and NOX. If not just right,
please state your judgement as to what the standards should be.
2. In your judgement should the Administrator grant or deny the
suspension?
3. Please justify your position on health, economic and/or technological
grounds with a careful distinction between these grounds.
4. Identify all past and present sources and approximate amounts of
financial support of yourself and your institution or academic dept.
5. Who paid for your transportation and attendance expenses for this
presentation?
6.Who notified you of this seminar and/or suggested your participation,
and when?
/
Louis V. Lombardo
The Campaign is an independent, charitable, citizen's organization dedicated to protecting the public health and welfare Support for work on
consumer and environmental protection comes from tax deductible contributions, subscriptions to "Clean Air", and foundation grants.
-------
25" FES
Mr. Louis V. Lombardo
President
Public Interest Campaign
9711 MacArthur Boulevard
BethedjSa, Maryland 20034
Dear Mr. Lombardo:
The Environmental Protection Agency will not honor your request of
February 12, 1975 to interrogate the speakers who participated in the
Scientific Seminar on Automotive Pollutants with the questions you
submitted.
I believe the questions stated in your letter are not relevant to
scientific research findings, which was the purpose of the seminar.
Sincerely yours,
Herbert L. Wiser
Deputy Assistant Administrator
for Environmental Sciences
HMThron:raw;2/25/75 rm. 919 50644 (REWRITE)
ARS Reading File
STA File
-------
February 26, 1975
Mr. Louis V. Lonbardo
President
Public Interest Campaign
9711 HacArthur Boulevard
Bethesda. Maryland 20034
Dear Mr. Lonbardo:
Mr. Train has asked me to respond to your letter of February 13,
1978 to Mat concerning my denial of your request to query participants
1n the recent Scientific Seminar on Automotive Pollutants.
After reconsideration of the nature of your request In relation
to the purpose of tne Seminar, I have reached the saM conclusion
based on the sene premise: your propoied questions are not relevant
to scientific research findings. Therefore, I again deny your request.
Enclosed are names and addresses of the Seminar speakers so
that you My question them directly, 1f you with.
Sincerely yours,
Herbert I. Wiser, Ph.D.
Deputy Assistant Administrator for
Environmental Sciences
Enclosure
cc: AX-563
ARC
ARS
Reading File
HWISER:csc: RD-682: x50655: OES/ORD: 2/26/75
-------
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
NESFAW.M AND I>EVI LUPMILN I
Dr. Carl Shy
Institute for Environmental Studies
University of North Carolina
Chapel Hill, North Carolina 27514
Dear Dr. Shy,
After the close of the Scientific Seminar on Automotive Pollutants, in
which you participated several weeks ago, we were requested by Mr. Louis
Lombardo, on behalf of the Public Interest Campaign, to submit several
questions to you regarding your presentation and background. The Public
Interest Campaign is a citizens group which has taken an active interest
in the question of whether this latest suspension of automotive emissions
standards should be granted.
Although the Seminar was not conducted in the same manner as the actual
suspension hearings, where questioning of persons testifying was part of the
procedure, Mr. Lombardo believes that the information he has requested
of you is relevant to the decision-making process and his group's under-
standing of all the underlying factors. As requested by him, I am forwarding
a copy of his questions to you for your consideration. Any answers you
believe are appropriate to these questions should be sent directly to
Mr. Lombardo. I would appreciate receiving copies of any response you send
to him. With respect to question no. 4, Mr. Lombardo has indicated
to us that he is concerned only with post-1965 information.
Very truly yours,
Herbert L. Wiser
Deputy Assistant Administrator
for Environmental Sciences
Attachment
-------
Dr. James Pitts
Dr. John Redmond
Dr. Carl Shy
Mr. Louis Lombardo
Dr. Billings Brown
Dr. Harlod McFarland
Dr. Richard Ehrlich
Dr. Donald Gardner
Dr. James Fenters
Dr. Jean French
Dr. Sam Epstein
Dr. David Menzel
DR. John Knelson
Dr. Richard Stewart
Dr. Edward Radford
Dr. Steven Horvath
Dr. Daniel Menzel
Dr. Russell Sherwin
Dr. A.P. Altshuller
Dr. Basil Dimitriades
Dr. James Mahoney
Dr. R.A. Arasmussen
Dr. Thomas Hecht
Dr. Bernard Weinstock
Dr. John Kinosian
Dr. James Edinger
Dr. Bruce Bailey
Dr. John Heuss
Dr. Thomas Graedel
Br. Be&t Kleiner
Dr. Chet Spicer
Dr. R.A. Saunders
Dr. Alan Bandy
-------
March 7, 1975
Mr. Louis V. Lombardo
Public Interest Campaign
9711 MaeArthur Boulevard
Bethesda, Maryland 20034
Dear Mr. Lombardo*
I am responding to your question* sent to Dr. Viser concerning
participation in eh* Scientific Seminar on Autowotiv* Pollutant*. My
response* to your questions are aa follows:
1. Since I an not a health professional, I don't believe ny judgement
haa nuch weight. My impression haaed on nuneroua discussions involving
health proreaaionala ia that the atandarda are auffioiantly atrinyent and
perhapa alightly too stringent depending on how the margin or" aafety
ooncept ia applied.
2. Aa an JEFJt employee it ia not appropriate for me to comment on the
Adminiatrator'a actions.
J. See 2.
4. As an £PA and earlier as an ffJH? enployee my support has been through
the agency appropriation process.
5. My travel and expenses ware paid Jby oar laboratory's portion o/ the
travel allocation.
6. J was informed and Invited through Or. Herbert Wiser and his office.
Sincerely yours/
A. P. Altshuller
£>ire«tor
Chemistry and Physics Laboratory
OC: Dr. H. Wiser
-------
RESPONSE BY R. •". SAUNOQIS TO QUESTION SUaOTlKD BT L. V. LOMBARDO OF THE
PUBLIC IWTERBST OAKPAIDM (SBS
1. There are tines •when the concentration of hydrocarbons in the air
originating from natural SOUTOM easeed tho hydrocarbons in the air attributable
to Joan's activities. Thia occur* frequently in soas rural area*. There is
evidence that it also occurs in tatoan areae. itydroearbons from natural sources
are wry reactive and take part in the formation of photochemical oxLdants.
There seems to be little point in "Hatting the concentration of anthropogenic
hydrocarbons to a level that ean be •meertert by aatorally-occoring hydrocarbons.
I therefore bsllevo the proposed standards for hydrocarbons are too rUringent.
I of for no opinion as to the standards for CO aad
2. In ay judgnent the requested delay in the ijBjOejsjrafeation of aore rigid
standards for hydrocarbon eedseloos ehoold be (ranted.
3. See responoe to question #1.
U* I am a salaried eiaployee of the Naval Researoh Laboratory. I have no
other employer or active business intorosto. The opinions I eaq^reeaed at the
EPA hearings and OMitum- were sgr owu
5. Since I am aaeployed in Washington, D.C., 1 had no enponaos in commotion
with ay appearance at the hearings and sesdnar. J$r local transportation was
by Navy vehicle and private oar*
6. DP. L. Ooldnunts of EcoooMle* and Soienoe Planning inc., both previously
unknown to mt road of ay mark in the newspapers. He infomed as of the SPA
asotincs and suggeotod ay partiolpation 3 or It days prior to the event.
-------
UNIVERSITY OF CALIFORNIA
IHil'ARTMfiNT Ol Ml II OKOlOGY
405 HILCARD AVI'Nllli
I OS ANGBLES 24, CALIFORNIA
March 7,
Louis V. Lombarcb
i'ublic Interest Carrexaign
?/H Mac Arthur Blvd.
Bethesda, Md. 20034
Dear It*. Lombardo:
Dr. wiser has transmitted to me the list of questions, included in your
letter of February 12, and indicated your desire for answers by me. My response
to questions 1, 2 and J is that I hove not :iiade up my mind on this issue. As to
4,6 and 3 my research work at UCLA since 1965 has been supported by State of
California fund*/ vl~A U.S. Navy funds, $2G,202, and CRC funds, $50'%.
.' / presentation at s!ic recent Scientific Seminar on Automotive Pollutants was a
;>reli,,,i,!rration tinu attendance expenses-
Sincere ly,
James G. Edinger
JG£*I
cc: Dr* Wiser
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TEXACO
IMi'TIUll.lia'M I'lUUMICTN
KNVIHONMHNT vi, PHonor'noN TIOXACO INI
IJKl'AUTMKNT I'. (). noX M>H
HI'' VCON, NI'AV YORK
March 11, 1975
Dr. Herbert L. Wiser
Deputy Assistant Administrator For
Environmental Sciences
U.S. Environmental Protection Agency
4th & M Streets, S.W.
Washington, D. C. 20460
Dear Dr. Wiser:
This is in reference to your letter to me of March
4 which attached a letter from Mr. Louis V. Lombardo, asking
several questions of the participants in the EPA Scientific
Seminar on Automotive Pollutants.
Since the questions posed by Mr. Lombardo concern
health and personal matters which are not germane to the
atmospheric chemistry portion of the Seminar in which I par-
ticipated, I do not feel that answers to these questions are
relevant to the record of the Seminar. Accordingly, I do not
plan to respond to them.
Sincerely yours,
BSB-JAH
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
National Environmental Research Center
Research Triangle Park, North Carolina 27711
March 14, 1975
Louis V. Lombardo
Public Interest Campaign
9711 MacArthur Boulevard
Bethesda, Maryland 20034
Dear Mr. Lombardo:
In response to your request of February 12 to Dr. Herbert Wiser
I have the following comments.
1. I believe the Ambient Air Quality Standards for
hydrocarbons and carbon monoxide that we now have
are appropriate, neither too stringent nor too
relaxed. With respect to nitrogen dioxide, I
believe we need to acquire the sufficient data
necessary to establish a short-term standard.
2. I do not have adequate technical information to
decide whether the Administrator should or should
not grant a suspension. My background is in
Environmental Health. The Administrator's decision
will be based on Environmental Health as well as
technical considerations.
3. Not applicable.
4. I have been an employee of the Federal Government
since July 1969. My salary in various positions
I have held is a matter of public record.
5. As a Federal employee my transportation and
expenses for participating in the Scientific
Seminar on Automotive Pollutants was of course
paid by the Environmental Protection Agency.
6. I was notified of the seminar by Dr. Wiser as
soon as he was informed that such a seminar
should be conducted.
-------
I regret this response does not come in time to have any
influence on the Administrator's decision. The letter of February 12
to Dr. Wiser was forwarded to me on March 4, 1975.
If I can be of any further assistance in these matters, please
do not hesitate to contact me directly.
Sincerely yours,
tUn
John H Knelson, M.D.
Di rector
Human Studies Laboratory
Dr. Herbert Wiser
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STATE OF CALIFORNIA—RESOURCES AGENCY EDMUND 0. BROWN JR., Gov»tno
AIR RESOURCES BOARD
1709 - llth STREET
SACRAMENTO 95614
Maroh 17, 1975
Mr. Louie V. Lombard©
Public Intaraat Campaign
9711 MaoArthur Boulevard
Betheada, MS 2003^
Dear Mr. Loabardo:
Dr. Herbert L. Wiser, Deputy Assistant Administrator
for fixvironaantal Sciences, U.8.K.P.A., has sent to
•e a copy of your letter of February 12, 1975 con-
cerning questions for the speakers at the Scientific
Seminar on Air Pollutants held in Washington, D.C.,
on February 10-12, 1975- I received the letter after
the suspension hearings, and therefore I aa not
answering the questions. However, I will be pleased
to provide the answers if you feel that they are of
use to you at this tine.
Sincerely yours,
John R* Kinosian
Chief, Division of Technical Services
JHJCijb
cc:vXDr. Herbert L. Wiser
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UNIVEBSITY OF CALIFORNIA, SANTA BARBARA SAi-TABABBAHA, CAUFOBN* '
c
0
p
Y
March 20, 1975
Mr. Louis V. Lombardo
Public Interest Campaign
9711 MacArthur Boulevard
Bethesda, Maryland 20034
Dear Mr. Lombardo:
Your letter arrived recently.
1) Can only answer for CO. Levels approximately correct
for healthy individuals. More research needed to
answer question.
2) No opinion.
3) I developed no position. Just presentation of facts.
4) Research support for studies on CO received from
Air Resources Board, State of California and from
University funds.
5) Was attending another meeting in Washington and left
it for presentation.
6) EPA office notified re meeting. Was pleased to
present research results. A listing of our published
work on CO is attached.
Sincerely,
Steven M. Horvath
Director and Professor
SMH:fb
Enclosure
cc: Dr. Herbert L. Wiser, EPA
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INSTITUTE OF 11NVI RONMi-NTAL STRESS
Publications and Manuscripts
Concerning Carbon Monoxide
Sleven M. Ilorvath
b Director
PUBLISH!-!)
Raven, P. B., B. L. Drinkwater, S. M. Horvath, R. 0. Ruhling, J. A. Gliner,
,1. C. Sutton, and N. W. Rolduan. Age, smoking habits, heat stress,
and their interactive effects with carbon monoxide and peroxyacetyl-
n ilr.ile on man's aerobic power. Int. J. Bionieleor. 18(3): 222-232,
1974.
Dahms, T. E. , and S. M. Horvath. Rapid, accurate technique for
determination of carbon monoxide in blood. Clin. Cliem. 20(5):
533-537, 1974.
Drinkwater, B. L., P. B. Raven, S. M. Horvath, J. A. Gliner, R. 0. Ruhling,
N. W. Bolduan, and S. Taguchi. Air pollution, exercise, and heat
stress. Arch. Environ. Health 28: 177-181, 1974.
Raven, P. B., B. L. Drinkwater, R. 0. Ruhling, N. W. Bolduan, S. Taguchi,
J. A. Gliner, and S. M. Horvath. Effect of carbon monoxide and
peroxyacetylnitrate on man's maximal aerobic capacity. J. Appl.
Physiol. 36(3): 288-293, 1974.
Raven, P. B., B. L. Drinkwater, and S. M. Horvath. Physiological effects
of air pollutants during long and short term work in 25°C and 35°C
temperature. Final report on Grant ARB-2098 of the California State
Air Resources Board, June, 1974.
Horvath, S. M. Effects of carbon monoxide on human behavior. IN:
Proceedings of the Conference on Health Effects of Air Pollutants,
Assembly of Life Sciences, National Academy of Sciences - National
Research Council, October 3-5, 1973, pp. 127-144.
Horvath, S. M., T. E. Dahms, and J. F. O'Hanlon, Jr. Carbon monoxide
and human vigilance: a deleterious effect of present urban
concentrations. Arch. Environ. Health 23: 343-347, 1971.
Horvath, S. M., P. B. Raven, B. L. Drinkwater, J. F. O'Hanlon, and
T. E. Dahms. A brief literature search regarding the influence
of air pollutants on work capacity and psychophysiological
responses of man. Proj. Clean Air Task Force Assessments,
2: E-l-25, 1970.
Horvath, S. M., J. F. O'Hanlon, Jr., and T. E. Dahms. Carbon monoxide
and vigilance: potential danger from existing urban concentrations.
Proj. Clean Air Rep., 2: 1-11, 1970.
-------
INSTITUTE OF ENVIRONMENTAL STRESS
Publications and Manuscripts
Concerning Carbon Monoxide
Horvath, S. M. 1-lTi.T.ts of r.irbon monoxide during ex<.-rrise. Serlion V
of National Research Council Panel on Carbon Monoxide report to
the U.S. Senate Committee on Public Works, 1974.
Ilorvath, S. M. Populations especially susceptible to carbon monoxide
exposure owing to reduced oxygcnation at altitudes above sea level.
Section VI I (D) of National Research Council Panel on Carbon Monoxide
report to the U.S. Senate Committee on Public Works, 1974.
MANUSCRIPTS IN PRHSS
Dahins, T. E., S. M. Horvath, and D. J. Gray. Technique for accurately
producing desired carboxyhemoglobin levels during rest and
exercise. J. Appl. Physiol.
Horvath, S. M., P. B. Raven, T. E. Dahms, and D. J. Gray. Maximal
aerobic capacity at different levels of hemoglobin. J. Appl.
Physiol.
Wagner, J. A., S. M. Horvath, and T. A. Dahms. Carbon monoxide
elimination. Pespir. Physiol.
MANUSCRIPTS SUBMITTED OR TO BE SUBMITTED
Gliner, J. A., P. B. Raven, S. M. Horvath, B. D. Drinkwater, and
J. C. Sutton. Man's physiologic response to long-term work
during thermal and pollutant stress. J. Appl. Physiol.
Horvath, S. M. Influence of carbon monoxide on cardiac dynamics
in normal and cardiovascular stressed animals. Final report
on Grant ARB-2096 of the California State Air Resources Board.
Raven, P. B. , B. L. Drinkwater, J. A. Gliner, S. M. Horvath, and
J. C. Sutton. Spirometric changes following long-term work
in polluted environments. Environ. Pes.
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Ford Motor Company 20000 Rotunda Drive
Dearborn, Michigan 48121
Mailing Address:
la io-»c P.O. Box2053
April -LH , 1975 Dearborn, Michigan 48121
Mr. Louis V. Lombardo
Public Interest Campaign
9711 MacArthur Boulevard
Bethesda, Md. 20034
Dear Mr. Lombardo:
In response to your letter of February 12, 1975 to Dr. Wiser, which
requested that the speakers at the seminar answer six questions, I
submit to you my answers.
1. I am not a medical expert and therefore not competent to judge
the Air Quality Standards. However, I believe that the AQS for HC's
is inappropriate because HC's at low concentrations are not a health
hazard themselves.
2. The Administrator should grant a suspension.
3. My position is based on analysis of air quality improvements to be
expected from emissions control. I have sent you a number of my re-
prints relating to this subject.
4. Ford Motor Company.
5. Ford Motor Company.
6. Dr. A. P. Altshuller of EPA about ten days before the seminar.
Sincerely,
•>
••'7/1
B. Weinstock
Manager, Chemistry Department
Scientific Research Staff
BW:ml
cc: Dr. H. L. Wiser''
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E. COMMENTS/COORDINATING RESEARCH COUNCIL
-------
COORDINATING RESEARCH COUNCIL
THIRTY ROCKEFELLER PLAZA
NEW YORK, N. Y. 1OO2O
SUSTAINING MEMBPRS
Amrikon Pplrolnuni Institute
Society of Automotive Enginectv Inc.
March 1, 1975
Mr. Harry Thron
Environmental Protection Agency
Office of Environmental Sciences
Room 919-W (RD-682)
401 "M" Street, S. W.
Washington, D. C. 20460
Dear Mr. Thron:
At the recent Environmental Protection Agency Scientific Symposium held on
February 10 and 11 on automotive pollutants, Mr. Lombardo of the Public Interest
Campaign referred in his remarks to the CRC/APRAC research programs a joining
of the automobile and petroleum industries with EPA in "an unholy alliance be-
hind closed doors to do research on automotive pollutants." Clearly Mr. Lombardo
is misinformed and I would like to request that the material enclosed, along with
this letter, be placed in the public record on the symposium.
Of course the formal relationship between APRAC and the EPA was severed in
late 1973 — although informal technical liaison is still carried out. EPA stated
that their relationship with APRAC had been entirely constructive; however, they
decided to change their relationship to assuage the doubts of some who were con-
cerned with environmental matters.
A very clear description of the CRC/APRAC program and its organization was pre-
pared for the record and placed there by Mr. Ruckelshaus once before, and I
believe it would be appropriate to make that write-up a part of the record for
the February 10th and llth symposium as well.
Thank you for your consideration.
Very truly yours,
AEZ:n
Enclosure-
Alan E. Zengel
Project Manager
-------
STATEMENT FOR THE RECORD
INVOLVEMENT OF THE ENVIRONMENTAL PROTECTION
AGENCY IN THE ACTIVITIES OF THE
AIR POLLUTION RESEARCH ADVISORY COMMITTEE :
OF THE COORDINATING RESEARCH COUNCIL {
The participation of the Environmental Protection Agency in the program
!
of the Coordinating Research Council (CRC) through the Air Pollution
Research Advisory Cormiittee (APRAC) is a viable means for optimising
the Nation's resources, both technical and financial, to improve the
•v
scientific and technical base for control of motor vehicle emissions.
It must be recognized that the CRC/APRAC program is not involved either
in the promulgation of regulations for the control of vehicle cmius-io-i.-;,
which is a governmental prerogative, or the development of hardv&rc to
enable regulations to be met, which is the primary responsibility of
automobile manufacturers (albeit also a responsibility of government in
\.^
relation to fostering the attainment of prescribed regulations) . lVit;)--c
the program is aimed at providing sound scientific and technical c1:..':.' cr
which both of these operations are based. Close coordination of; Llicjue
purely technical operations is not only prudent in regard to manpover
and funding, but it provides close liaison in a field that is rapidly changing
in a context vhere time constraints for setting standards by the govern-
• •
ment and meeting them by industry is critical. In the area of motor
vehicle emissions control, where available time to meet goals established
by the Clean Air Act is minimal, it would be prudent, in the absence of the
CRC/APRAC program, to establish close coordination in any case on many of
the activities now being handled through CRC/APRAC program.
-------
The management of the CRC/APRAC program la a joint venture shared
equally by the CRC supporters (the Automobile Manufacturers Anoocinti.on
i
and the American Petroleum Institute) and the Environmental Protection
Agency. All of the administrative activities of the program, starting
'•
with the planning of projects and ending with the publication of rcsenrcVi
reports, are jointly shared. The Environmental Protection Agency has
full voice in deliberations on all of the projects undertaken in the
CRC/APRAC program when EPA contributes to this funding or not. A
complete delineation of the CRC/APRAC operations, including preliminary
programming for 1972 and 1973 operations, is disclosed in the attachu-d
report entitled, "APRAC Research Program for 1972, Air Pollution Ilasertrch
Advisory Committee of the Coordinating Research Council, Inc., April 15,
1971." It is pertinent to note that management functions do not include
fiscal decisions. There is no blanket agreement by EPA relative to fu-jclinf;
of all of the projects in the APRAC program; rather the cor.uniturjnt oJ ft nur.
by EPA is dependent en EPA priorities and funding capabilities c.nd it; bmcd
on the type of study and the support EPA is giving to other closely
related projects in our own facilities or.by separate contract.
• .
For management of thie APRAC program, a number of groups have been established;
EPA has membership on all of these:
(1) Air Pollution Research Advisory Committee (APRAC). EPA has four
members out of 18 on this committee. (At its option, EPA could name
three additional members to bring EPA membership on a parity to that
of the. API or AMA.)
-------
(2) Executive Committee. EPA has one member on this committee with
a total membership of three.
(3) Engineering and Sctentific Advisory Group. EPA has three members
on this group with a total membership of nine.
(A) Medi c al Advisor v Group. EPA has two members on this group with
a total membership of eight. (At its option, EPA could name another
member,)
(5) Public Relations Advisory Group. EPA has one member on this four-
man group.
(6) Publieati on s Adv i s ory G r ou p s. EPA has a member on each of the
four-man publications groups for medical projects and a member on
the three-man group for engineering and atmospheric projects.
(7) Project Groups. EPA hes representatives on each of the project
groups that directs the projects sponsored by APRAC including both
contract projects and those conducted directly by the project group.
Salient steps in the prosecution of the APRAC program are as fo?.lowy:
(1) Program Planning. Plans for support of future projects are
developed by,the Research Advisory Groups from proposals submitted by
members of the APRAC, from the Project Groups, or otherwise brought to
the attention,of APRAC, e.g., unsolicited proposals by research groups.
These proposals are then discussed, priorities are set and a list of
projects for future implementation is established contingent on funding
capabilities.
-------
Fiscal Considerations. The program plans are submitted to the
API, AMA and EPA for approval as review with respect to priorities
and allocation of funds. Based on this review the future protjnim is
delineated for implementation. Consideration of funding by EPA is
on a project-by-project basis.
(3) Project Direction. Each project is directed by a Project Group,
composed of members of all three sponsors, which is responsible for
the development of the project, preparation of documsntation for
solicitation for research sources, technical review of qualification
of research sources, preparation of documentation for issuance of
requests for a proposal (RFP) to accomplish the required research,
technical review of the proposal and selection of the contractor,
monitoring of the contract, and review of reports and publications
resulting from the contract.
(A> Contrac t Negot iat ions. All procedures for the solicitation of
qualifications statements for research sources, solicitation of
requests for proposal, and contract negotiation are handled through
the Procurement Office of EPA in accordance with governmental contract
t
procedures followed for all contract negotiations by EPA. Any patentable
Item developed through a CRC/APRAC is dedicated for public use.
*
(5) Project Approval and Reviexj. The Air Pollution Research Advisory
Committee (APRAC) holds meetings approximately quarterly to review
progress on individual projects and the status of the program. Changes
in programing from that indicated by the planning document trc
subject to approval by APPJ\C. Projects developed end selectee! for
-------
contracting by the project groups require individual review by the
APRAC members and approval in writing.
(6) Reports and Publicetions. Reports resulting from APRAC projects
(e.g., contractor's progress or final reports), in addition to review
by the Project Groups, are submitted to all members of the APRAC
for review, acceptability of content, recommended changes nnd/or
additions, and opinion as to desirability of submitting to the
o
Clearinghouse for Federal Scientific and Technical Information,
operated by the U. S. Department of Commerce/National Bureau of
Standards, in order to make these reports available to the public.
The question of not entering reports into the Clearinghouse is cue
of judgement as to interest of the public in the reports not .the
nature of the research results; to date all significant reports have been
entered into the Clearinghouse. Publications are subject to review,
not only by the Project Groups, but by APRAC members arid by the ru' Vi.c.-i-
tions. Advisory Groups. Through the latter groups, normal EPA c?.cai:anc«j
procedures are followed. It is noted that reviews of reports and
publications apply to thg information developed by the CRC/APRAC projects.
' Subsequent.Interpretation of these data, by the government or industry
sponsors, or the general public, is not the purview of CRC/APRAC.
Value of the CRC/APRAC program to EPA. The projects undertaken and the
scientific and engineering information developed through CRC/APRAC
projects incorporate principally the full spectrum of knowledge
required to establish^ regulations for control of vehicle emissions. A"
-------
the same time, however, some of this knowledge is requisite to the
understanding of the problems related to control of emissions. APRAC
projects can be subdivided for evaluation of their merit to EPA into
three categories: (1) effects of pollutants, (2) chemical and physical
characteristics of pollutants as emitted or as transformed in the
atmosphere, and (3) vehicle use characteristics.
-------
Effec ts of Pollutant s. APRAC projects in this area concern effects of
carbon monoxide (six projects), oxidants, nitrogen oxides, nitrogen oxides
plus oxidants, p61ynuclear hydrocarbons, and a study of synergistic
effects covering a variety of pollutants.
i
>
Primarily these studies relate directly to EPA's responsibility fov the
development of air quality criteria documents and the promulgation of r.ir
quality standards and regulations on fuel composition. EPA will continue
to support work in this area consequent to the need for establishing
and revising standards and regulations. The interest of the CUG in this
support is basically the same as EPA's--to establish a firm foundation
for standards and regulations so as to obviate unnecessary economic pc;;r
through over-restrictive standards.
Association of EPA with the CRC in this work has several advantages to
EPA: (1) it stretches governmental funds, which are quite limited in this
as in other areas as well, and allows a much larger array of studies to bz
undertaken than would otherwise be the case; (2) through the joint direction
of these projects with knowledgeable medical experts from the petroleum
and auto industries, it improves the design and conduct of studies in that
competing philosophies are recognized; from this point of view It improves
the quality and acceptability of the results to both groups; and (3) since
the Nation's resources for conducting this type of study is severely
limited, it optimizes the use of the same talent available to and which
oust be turned to by both EPA and CRC.
-------
Although obviously there are biases as to the motivations of EPA
and the CRC in their desire to support such studies, there can be no
bias in the quest for scientific fact even though the next step—the
interpretation of these data—may lead to confrontation. However,
recognition of all points of view in the design of the studies should
minimize later confrontation in the interpretation of results, end gl
a basis for understanding that otherwise would not exist.
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Chemical and Physical Characterization of Pollutnnta. APRAC projects
in this area cover a wide range of studies characterizing both gaseous
and particulate pollutants as emitted from sources and their transport
i
and transformation in the atmosphere. Included are investigation of i
i
background pollutants of the same types associated with vehicular
emissions (e.g., carbon monoxide and haze) .and measurement technique !
and instrumentation.
These efforts have been directed towards five general objectives:
(1) Improved quantitative assessment of the contribution of control
of motor vehicles to reduction in hydrocarbon, nitrogen oxide, anJ
oxidant concentration level and polycyclic organic concentration love?13
in cities.
(2) Determining the relative contribution of motor vehicles, stationary
sources and natural sources to haze and visibility reduction.
(3) Developing criteria for standardized operation of environr-.enta!!
irradiation chambers.
(A) Obtaining better relationships between engine-fuel parameters-and
exhaust emissions of polycyclic organica.
(5) Developing improved instruments or analytical methods for aldehydes
and polycyclic organics in motor vehicle exhaust and for characterizing
diesel odor. Such analytical techniques are nee'ded as part of any future
regulations with regard to these pollutants.
These projects are fully compatiSle with research needs of EPA. If the
projects had npt been conducted on a cooperative basis, it is doubtful
-------
whether resources vould have been available to carry out several
of these projects during this period of time. Several of the more
•v
pertinent studies of particular value to EPA are discussed in
greater detail below.
Atmospheric Recction Studiea. The project'entitled, "Atmospheric T.^c'jJ.ca
Studies" was originally conceived by staff of EPA in 1968. Such fieLf!
studies were being conducted on a small scale by an in-house research
group, but personnel limitation prevented enlarging this in-houy^
activity. A contract program was needed to provide more extensive field
research efforts, but resources were insufficient to completely fund
such an effort. EPA personnel proposed' that the project be incorporaC-;!
into the APRAC program. Major experimental studies were conducted in
Los Angeles in 1968 and 1969 aad in New York in 1970. The study sites
were agreed upon on the basin of EPA needs as well as CRC/APRAC intoriiS':.
The experimental results obtained provided en excellent data hac-j foe
analyses of hydrocarbon reactivity in the atmosphere, relating atmospheric
hydrocarbon composition to source emissions of hydrocarbor.3 and relating
•
oxidant concentration and nitrogen dioxide concentration levels to
hydrocarbon and nitric oxide emissions. Such data were utilized by EPA
i
as part of the information base for promulgation of air quality standards
for -notor vehicle pollutants. The results have also made it possible
for EPA to supply the data base, needed for mathematical modeling of
photochemical air pollution by several contracts funded exclusively by
EPA. In addition, EPA staff urged the development of a diffusion trcj
-------
project group effort In APRAC. Such n group was act up and haa been
active in modeling carbon monoxide transport.
Diesel Exhaust. At present panels of human subjects provide the only
means of characterizing diesel exhausts. _Whtle such panels cnn be u;;od
as part of research projects, such an approach is not practical for
routine measurement of odors for the purpose of determining compliance
vith diesel odor regulations. Either a manual or instrument technique 1.s
urgently needed to permit implem.cnting a dicnel odor regulation. Tlvj
chemical characterization of diesel odor haa posed a very complex
scientific problem. Despite work by several different research labora-
tories in the last few years, no simple analytical approach hrs bc-.cci.iM
evident. Because of the importance of the problem, research continuen,
since chemical characterization and development of an analytical toch".fnuo
appears feasible using all available current research approaches. Cent:-it",1*.?
association with CRC-APRAC in this area is desirable to bring the talcs',-.
of all groups Interested to bear on developing the scientific data required
to enable regulations to be promulgated for control of diesel emissions.
Organic Particulates in Exhaust. Several APRAC projects are concerned with
Improved methods of analysis of polynuclear aromatlcs and phenols and particu-
lates In vehicle exhaust. Such results are needed to serve as the basis
for measurement requirements for additional Federal regulations specifically
limiting these types of emissions. Since the technical requirements for
this task are quite sophisticated, It is highly desirable that government
and Industry cooperate In this task to insure results that are pr.iei:icnl
for application not only for certification and surveillance purpo-:aj bvt,
-------
in addition, for use during the control hardware developmental phnse
by industry.
Factors Affecting Reactions in Environmental Chambers. Previous evalua-
tion of product yields and rates of reaction of smog reactions in
environmental irradiation chambers have shc-wn significant nutr.ericnl
differences among various laboratories active in this area. Although
the differences are no greater than among investigations of a nior<> b;iif.c
^.
nature of chemical reactions, a higher degree of agreement is desir.:.'->!;..
Such environmental chamber results provide an input to standards dcvali.-)
ment as well as to an understanding of atraoopheric processes. A sttciy
io now being funded to determine the importance of the severe!
possibly influencing the comparability of results between lebo
operating such environmental chambers. The results of this work uhruld
permit for the first time steps towards standardization of results rrv-.i
these environmental -chambers. Since such chamberc are utilized by bo'^.t
governmental and industrial groups, inclusion of this project in the
APRAC program is inherently logical.
Vehicle Use Characteristics. EPA is participating In a number of CRC/APRAC
projects in this area of work. The projects may be roughly subdivided into
three categories: (1) studies related to the Identification and character-
lection of motor vehicle pollutants; (2) studies related to defining
typical usage patterns for vehTcles; and (3) studies related to evaluation
of problems posed by motor vehicle emission control technology. In all
-------
cases but one, these studies have been performed by private ronenrch
organizations; other Government Agencies, or academic institutionu--
the same sources to which EPA looks to in obtaining contract support for
its own independently sponsored studies.
Efforts related to the identification and characterization of motor
vehicle pollutants have provided basic information on such subjects ns
the types of chemical compounds responsible for the offensive odor of
diesel engine exhaust and how to define them. EPA employs such informa-
tion in assessing the need for and feasibility of controlling various
motor vehicle emissions although these cooperative studies do not provide
the sole basis for making such decisions. .The results of these studies
are of value to the industrial participants because they provide back-
ground data needed in developing emission control technology for thase
pollutants.
Projects related to determining typical vehicle uscge patterns provide.
EPA vith data useful in the development of vehicle testing procedures.
Test procedures used by EPA in certification of new motor vehicles are not
developed in these cooperative studies. All such procedures development
is conducted in efforts solely under the control of EPA.
CRC/APRAC projects related to evaluation of problems posed by emission
control technology are basic in nature; they do not include developrrant
of control technology which will subsequently be applied by automobile
manufacturers. Thejnost important project of this type is an intensive
-------
study of vehicle maintenance and emission inspection as a means for
i
reducing emissions from in-use vehicles. The results of this vork,
vhich calls heavily on experience available primarily to the automobile
and petroleum industries, a're expected ~to, be. of great value to SPA j
as a part of its program to develop an effective means of conducting
motor vehicle emission inspection and maintenance. It in anticipated
that such inspection and maintenance programs vill be needed by scr.,a
states in achieving national ambient air quality standards. H^re .ivjn.'ri,
only basic information is being developed; decisions on pr omul" at ion iir
regulations based on these and other data are a separate activity in !£''.'* .
Summary. The association of EPA with the CRC/APRAC program is
to be a viable means for bringing the Nation's limited manpov/er r.«d fiscal
X^
resources to bear in an optional fashion en establishing- improved scti.i-
tific and engineering knowledge related to the responsibility o? Lha
government for setting regulations and the petroleum and automobile
manufacturers to provide the means for control. Adequate safeguards are
provided to protect the prerogatives of the government through the
established procedures of (1) full partnership of EPA in all management
decision, including project planning, direction and review; (2) selectivity
of project support by EPA on a project-by-project basis; (3) negotiation
of all contracts through EPA contract procurement channels; (4) opportun-
ity .for review of all project reports and publications, and (5) full
disclosure of all information to the public.
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F. CORRESPONDENCE FROM
AMERICAN PUBLIC HEALTH ASSOCIATION
-------
j.N'i~ED Jj
ENVIRONMENTAL PROTECTION
WASHINGTON. D.C. 204-50
AGENCY
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.-.nericar: Public Health Association
1:15 Eighteenth Street, N.W.
Washington, D.C.
Dsar Dr. Miller:
20036
Yoxir letter of February 5, 1975, to the President was
rsf erred to this Agency for reply. We were most interested
to receive your views concerning the proposed relaxation
of the autoaobile emission standards. The Environmental
Protection Agency is keenly aware of the potential danger
which automotive pollutants pose to the public health and
welfare, and we are in agreement with your position that
concern, for this danger should be of paramount importance
5_~ong the factors which contribute to any decision concerning
the eaission standards. Indeed, Administrator Train has
r-^blicly stated that, although he supports the President's
reccr-.ar.dation, he believes he has an obligation to work
to/arc, a modification of that recommendation if the factual
rerord which EPA is currently compiling supports such a
Q
The task of compiling such a record is being accomplished
means of both a public hearing and a public symposium.
5 hearing is being held in two parts.. The first was
Id from January 21, 1975, to February 7, 1975, and it
vclved the technological issues inherent within the
irairenent of meeting the standards. The second part will
-rr.ence or. February 18, 1975, and will focus on the question
the potential adverse health effects that may result
Dm -che sulfate emissions of automobiles equipped with
talytic converters, as well as the issue of how best to
iuce these emissions if a potential health problem is
-~d to s:-:ist. The symposium was held this week and
ied yesterday, February 12, 1975. It addressed the issue
:ects caused by the introduction of automobile
: = -_;sr emissions, primarily oxides of nitrogen, into
i atmosphere. Public participation is encouraged in all
r.'.ese proceedings.
CONCURRENCES
FONM 13»O-1
OFFICIAL FILE COPY
-------
-2-
Your letter will be entered into the record of the
Health Effacts Symposium, In addition, if you wish to
further contribute to that record, you should contact
3r. Herbert L. Wiser, Deputy Assistant Administrator for
Environmental Science (755-0644), Also, if you desire
ro participate in the Sulfate Hearing, you should contact
Mr. Eric O. Stork, Deputy Assistant Administrator for
Mobile Source Air Pollution Control (426-2464).
Sincerely yours,
/s/ Richard H. Johnson
Richard H. Johnson
Acting Assistant Administrator
for Enforcement (EG-329)
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AMERICAN PUBLIC HEALTH ASSOCIATION
1015 Eighteenth Street, N.W., Washington, D.C. 20036 • (202)467-5000
February 5, 1975
rf \ The President
v-- The White House
-/ 1600 Pennsylvania Avenue, N.W.
Was hington, D. C.
Dear Mr. President:
The American Public Health Association, a non-profit
professional association representing many of the leading
health authorities in the United States, would like to
express its concern regarding proposed relaxation of the
automobile emission standards. ,
We are not impressed with industry's claims that fuel economy
can be achieved only with the relaxation of the auto emission
standards as set forth in the 1970 Clean Air Act and its
1971 Amendments. Studies conducted by both federal government
agencies and independent consulting firms indicate that 1977
and 1978 standards can be met with a 40% increase in fuel
economy.
Our major concern regarding your decision is the implications
such might.have on the health of the American public.
Review of the current health literature leads one to believe
that the current standards set forth by the Clean Air Act
do, in fact, allow protection for the majority of the American
public. Although these standards do not protect all of the -
population all the time — and the margin of safety in some
areas iar slight — they do demonstrate that we should expect
decreased morbidity and mortality associated with reduced
auto emissions. A departure from these standards as expressed
- in your proposed freeze at the 1975 California level except
for NOx, we believe, will mean a continuation of health problems
which are associated with periodic high levels of auto effluents.
For the thousands of persons who suffer from asthma, bronchitis,
-------
The President
February 5, 1975
Page 2
and other respiratory problems as well as aged persons and
others affected by cardiovascular disease, the continuation
of current levels of auto emissions can only mean continued
aggravated disease. We deplore the concept that these people
should continue to bear the burden of air pollution which
need not exist. All evidence that we have seen indicates
that fuel economy and emission control are not unrelated,
but are in fact harmonious. We strongly urge that as the
entire energy conservation and environmental protection program
evolves it should reflect deep concern for the public health.
Sincerely,
C. Arden Miller, M.D.
President
-------
G. NOTICE OF SEMINAR
-------
U.S. ENVIRONMENTAL PROTECTION AGENCY
SCrENTTKIC. SEMINAR ON AUTOMOTIVE I'OLI.UTANTS
Notice of Seminar
Notice is hereby given that a scientific, seminar will be held at
the Thomas Jefferson Memorial Auditorium, U.S. Department of Agriculture,
South Building, 14th Street and Independence Avenue, Washington, D. C.,
on February 10, 11, and, if necessary, February 12, 1975, each day
at 9:00 am.
The purpose of the seminar is to continue to assemble the most-
recent research knowledge on the health effects and atmospheric chemistry
of air pollutants from automobiles by offering the* scientific community
and other interested persons the opportunity to present information
through this forum.
Representatives of industry, environmental groups, government
agencies, universities and private research institutions are invited to
present and discuss research findings pertaiuing to the subject. The
principal concern of the seminar will be NOx because of recently devel-
oped information on this subject; however, the presentation of any new
information related to CO, HC, or other automotive pollutants is also in
order. Presentations should address the following agenda items:
(1) health effects (experimental animal and human studies); and (2)
atmospheric chemistry of NOx including the relationship of NOx to
hydrocarbons and the formation of photochemical oxidants.
-------
The meeting will be open to the public. Persons wishing to submit
a paper, attend, or obtain further information should contact" Dr, Harbor I-
L. Wiser, Deputy Assistant Administrator for Environmental Scie:nce.s,
Office of Research and Development (RD-682), Environmental Protection
Agency, Washington, D. C. 20460. The telephone number is (202) 755-0655.
Persons failing to notify EPA by February 3, 1975 of their intent
to give an oral presentation at the seminar shall not be entitled to give
such a presentation except at the discretion of EPA, Such persons are
not precluded, however, from submitting written statements for the record,
/ \
Wilson K. Talley
Assistant Administrator^ for
Research and Development
-------
,
'L'.Y/.L PHO > '1C i'lON AGtiNCY ' »
• ,HINC.TO:I. c.' ':. :.'. vo I-CV-TJ.'. .st.-i. ; :.t •.;/.-. I
- ,/ . . I •. .'I '*O '•'-'-'.- - '• ' "' f IT T 1 C> .\ G '. ' . c. '
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O'Neill (202) 755-0344
EPA TO HOLD SCIENTIFIC SEMINAR ON AUTO POLLUTANTS
The ErLvironmeatai. Pro-tectd-Oit r^srtcY-" wiZ t ia.ald~.-a -oubiic -
" ~""r ' - - - . - __ -fr *
three-day scientiric- se^tlrar on- l.ne r:eaJ-t-/_ errcictjr- oj? srTjtczio--
«
tive pollutants, beginning :;o~ -u",y, Fobrua:-:-' .10, 1975.
EPA Adminis tratcr ilussell E. Tr^^In ar.r.oTT.cco the '.- err, in ax-
on January 21, 1975 in his opnn 1 .-.-r state.r.c-.r. h ;;t EPA's public
hearing on the requc-shs by Ford, (-"enaral I.:::.o-:r; end Chr^ sl&r
for one yaar suspension of the 1977 auto emission. standards
for- hydrocarbons and carbon monoxide. The hearing 3 are con-
tinuing at the Thomas Jefferson Auditorium., U.S. Department
of Agriculture, in Washington , n.C.
Train said that the purpot;^ of the scientific seminar is
"to bring out the l-?.tesr. scienLAfic inforrtation on tha impact
of auto pollutants, carticule.r"' 7 nitrocrer; oxides, on hurra n
health."
Train indicated that the .information gathered during the
symposium, along with, the record, of the suspension hearings
and submissions by the automakers, would, -provide "r.n authori-
tative record" botn for EPA ar.c. i^or- Congress, which ij rocpon
ble for long range decisions af r^cting auto emission s t arv.l -.. re'
and fuel economy improvements.
Ur.der tiie Cl'-in Air Act ir_L"?.-in m\ist c. ecidc trie i"f.T!3 t"'on
of a OPV ^'Orir suso?^iion of •!-'•;-- 1977 sta::'."""rc'^ not later than
March 3, 19/5 -- 6J - . -'.^ from tr - dato of tiie first rc.r-uos:;-.
for su-jp"n::ion (For.'" on Janu" 2, 1215', r
-! '• ,' i c'c flC'." . '.!] to r_ -•>.•-« t. i mat.--.!! ^.
1510-1 (K:-- .'. , . ;.->!
-------
Train indicated in hie o^'/ri. :v: shatc.^^r. '; that ho av-'l Pre-
sident Ford were in n? reemen c that tl:o r:-u.-v;-:."i.';ion decision
would not be inf lujaceu by the Prcs vJer.t ' i, roccxmeiixL, tic;i o [.
a five year freeze of the current California standards .tor th-3
rest of the country beginning v:!. ':.".-_ zhc-i 1977 rodal y'.iar.
The scientific seminar v/ill bs hslcl on February 10, 11
and, if necessary 12, beginning at 9 a.n. eie:ch day a.t the Thcruas
Jefferson Memorial Auditoriura, U.S. Department of Agriculture,
South Building, 14th Street and Ir.iepar.ciGvi::e Avenue., Washing-
ton/ D.C.
Representatives of industry, environ:r-cntal groups,
ment agencies, universities c^r.d private research institutions-
are invited to present and discuss research findings pertain-
ing to the health effects and ucrr.cspheric cheiaistry or auto
-r*i:atedr~ai-r;-poilution. --. ......_.-
-'Specifically, presentations should address- .Tp- health
effects (experimental! ar.inal ar:-d hTrran studies} 2}r-atir-ospharic
chemistry of KOx including the reTatior.ship of HO:?"to hydrocar-
bons and the formation of photoaheirJLca.?.. o:;:ic.ants. .
Percons v/ishing to subr.i';, ? --^31- c"~ obtain further infr^r-
mation should contact Dr. Herbert L. Wis^r, Deputy Assistant
Administrator for Environraontal Sciences. Office of Research
and Development (RD--5.82) , Environmental Protection. Agsncy,
Washington, D.C. 20460. telephone: (202) 755-0655.
February 3, 1975 is the deadline for- parsons wishing to
give an oral presentation at the seninar to notify EPA.
Written statements may be submitted, for the record, up to the.
close of— the seminar.
Copies of Administrator Train's openirtg statement at the
1977 suspension hearings are available from the EP?». Press Offic
Room 339, 401 M Stteet, Sr.'7., Washington, D.C. 20450.
-------
H. PAPER:
CLARENCE M. DITLOW III
-------
SHORT-TERM NITROGEN DIOXIDE LEVELS
Clarence M. Ditlow III
Public Interest Research Group
February, 12, 1975
The Environmental Protection Agency's (EPA's) analysis
of the impact of a relaxation of the statutory 0.4 grams
per mile (g/m) oxides of nitrogen motor vehicle emission
standard on ambient air quality looks only to the current
annual ambient air quality standard of 100 micrograms per
cubic meter (ug/irr) for nitrogen dioxide (NO ). The EPA
analysis does not look at the impact of relaxation of the
statutory emission standard on short-term N0? levels. Consequently,
the EPA analysis concludes that only two cities, Chicago and
Los Angeles, will exceed the ambient annual N02 standard by
more than 10 ug with a relaxation of the oxides of nitrogen
standard to 3-1 g/m.
The following is a partial analysis intended to spur
full analysis of the implications of short-term N0p ambient
standards as suggested by Dr. Carl Shy of the National Research
Council-National Academy of Sciences Panel on Nitrogen Oxides.
(Dr. Shy suggested ambient N0? exposure levels of 375-475 ug/m
for one-time, one-hour and 140-280 ug/m for repeated two to
three hours at this symposium on February 10, 1975.) This
analysis is based on one-hour N0~ chemiluminescent readings
for the latter part of 1972, 1973 and 1974 for a limited number
of cities not thought to have an ambient N02 problem in EPA's
analysis — Atlanta, , the District of Columbia, Denver,
Philadelphia and Springfield, Massachusetts. It does not
include Chicago and Los Angeles, the two cities with an admitted
NOp problem, and Chattanooga, the city which has the most frequent
short-term excursions according to Gardner Evans of EPA's National
Environmental Research Center.
-------
-2-
With a motor vehicle emission standard of 3.1 g/m for
oxides of nitrogen, Philadelphia is said not to have an NO,,
o
problem because projected 1-985 levels would be 109 ug/m
or within "measuring error" of the annual average standard of
100 ug/m3. But from January 1973 through December 197^, Dr.
Shy's one-hour NO^ level of 375 ug/m was exceeded four times.
Two hour levels in excess of Dr. Shy's level of 140 ug/rrr were
much more numerous. Just taking back-to-back one-hour N0p
measurements in excess of 1^0 ug to get an indication of how
many times a two-hour average NO- standard of 1^0 ug/m would
be exceeded, the EPA data revealed 525 excess two hour excursions
in 1973 and 487 during 197^. If one were to average two hour
values, the number of excess N0? excursions would go up still
further. For example, during June 197^5 there were 139 two
hour periods with NOp levels in excess of 1^0 ug. Averaging
one-hour N0? levels over two hours increased the number of
two hour NOp excursions to 172 for June 197^ in Philadelphia.
Springfield, Massachusetts apparently should be on EPA's
list of cities violating even the annual average NO standard.
for the Springfield average ambient N0_ level from September
1973 through August 197^ was 132 ug/m3. From August 1973
through November 197^5 ambient one-hour N0? levels in Springfield
•3
exceeded 375 ug/m 57 times. Two hour N0? excursions in excess
o
of 1^0 ug/m were too numerous to count by hand. But just during
the months of June to August 197^> there were 1,257 two hour
periods with each hour in excess of 1^0 ug/m .
Denver, Colorado is another city said to be without a
long-term N0? problem. From December 1972 through September
197^j one hour NO,, readings exceeded 375 ug/m 56 times. Two
hour NOp levels in excess of 1^0 ug/m were again too numerous
to count. But just during the month of January 197^, there were
218 two hour periods with each hour exceeding 1^40 ug/m . Averaging
the hourly readings over two hours would have sent the number
of excess two hour periods still higher.
-------
The District of Columbia is also without an N02 problem
according to the EPA's long-term analysis. Yet from January
1973 to December 1974, one-hour N0? levels exceed 375 ug/ra^
three times. During summer months, two hour levels frequently
•3
exceed 140 ug/rrr as was the case in August 1973 when there were
120 two hour periods with each hour exceeding 140 ug/m .
How about Atlanta, Georgia which does not even make the
EPA list of cities with potential N0? air quality problems.
During 1974, one-hour N02 levels in Atlanta exceeded 375 ug/nr
five times. Two hour NOp levels in excess of l40ug/m are
again very numerous, particularly in the summer months. But
even October 1974 had 154 two hour periods with each one-hour
NOp reading in excess of 140 ug/m .
CONCLUSION
Any analysis of the need for the statutory 0.4 g/m oxides
of nitrogen motor vehicle emission standard which looks only at
annual N02 levels must err when one considers the demonstrated
need for a short-term N0_ standard. The impact of a short-term
N0_ standard on motor vehicle oxides of nitrogen emission
standards becomes even more severe than the relationship of the
short-term standard to the long-term standard when one
considers the diurnal variation in ambient N0? in urban areas
caused by traffic patterns. The short-term NOp data available
for a limited number of cities said not to have an NOp problem
under EPA's annual average standard analysis indicates a severe
NOp problem does exist. The EPA must revise its analysis of
the need for the statutory oxides of nitrogen motor vehicle
emission standard to consider the short-term N0? health effects
which support the need for the statutory 0.4 g/m emission standard.
Clarence M. Ditlow III
Public Interest Research Group
Washington, D.C.
-------
I. CONCLUSIONS - ENVIRONMENTAL RESEARCH &
TECHNOLOGY, INC.
-------
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WTC/065/75
February 4, 1975
Dr. Herbert Wiser
Deputy Assistant Administrator
U. S. Environmental Protection Agency
401 M. Street, S. W.
Room 919 W. Tower
Washington, D. C. 20460
Re: Statement for EPA Hearing on NOX Control
February 10-12, 1975, Washington, D. C.
Dear Dr. Wiser:
This letter conveys a statement of my interpretation of the conclusions
on NOX control derived from the National Academy of Sciences Panel
on the relationship of emissions to ambient air quality. As you know,
the Panel was convened by the NAS/NAE Environmental Studies Board under
my chairmanship as a part of a larger group to examine several aspects
of air quality and automobile emission control for the U. S. Senate
Public Works Committee. The panel started its work in February 1974
and completed the draft report by July 1974. Our report was submitted
to the Senate Committee in early September of 1974*. The objectives
of the panel were to examine several aspects of the adequacy of ex-
isting emissions data, ambient air quality measurements, and methods
of predicting ambient air quality from changes in emissions of trans-
portation and stationary sources. The panel concentrated on the pre-
sently regulated pollutants, carbon monoxide, hydrocarbons, nitrogen
oxides and oxidant.
There are three aspects of the NOX question that must be considered.
First, the gas nitrogen dioxide (N02), a product of nitric oxide (NO)
oxidation, is regulated with an ambient air quality standard derived
from evaluation of health effects. Second, nitrogen dioxide plays
a key role in the atmosphere as a precursor with hydrocarbon vapors
to form photochemical oxidant. Third, NOX are precursors in the
formation of secondary aerosols, including their water, ammonium
and nitrate content. For these potentially hazardous particulate
pollutants, no basis has been clearly established for governing
regulations.
* National Academy of Sciences/National Academy of Engineering
Coordinating Committee on Air Quality Studies, "The Relationship
of Emissions to Ambient Air Quality", Volume 3, No. 93-24, Sept.
1974, U. S. Government Printing Office, Washington, D. C., 137 p
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Dr. Herbert Wiser February 4, 1975
U. S. EPA Page 2
Control strategies of NO to meet the ambient air quality standards
for each of the regulated pollutants NOo and oxidant may not neces-
sarily be the same, which creates a need for optimization.
Review of the measurements and analyses available prior to mid-summer
1974 indicated that there is considerable uncertainty in the emissions
data available for NOX, particularly for short-time resolution re-
quired for characterization of oxidant levels. Furthermore, there
is little information on the long-term reliability of present emission
control hardware either on mobile or stationary sources. Just this
month, the California Air Resources Board has made available a new
research report on emissions and control of NOX in the South Coast
Basin prepared by D. R. Bartz et al. Emission factors were experi-
mentally verified and fluctuation in time and space were assessed.
The maximum daily emissions during December and January are 30% higher
than annual average emission rates. Forty-seven percent of the total
is emanating from a 500 km2(192 m2) area in the S-W corner of the basin.
Unfortunately, that concentration of power plants and refineries is
upwind of a substantial portion of the basin. Even if all mobile source
emissions from this area were to be eliminated, the localized stationary
source emissions during stagnant conditions and typical inversion heights
were found to be sufficient to generate first-stage NC>2 alert, i.e.,
3.0 ppm "instantaneous" NOX level (actually about a 15-minute average).
In another report which I recently completed together with a number
of co-workers and to be released shortly by the California Air Resources
Board, it was demonstrated that the atmospheric conversion rates of
both S02 and NOX emissions influencing the accumulation of particulate
sulfates and nitrates may be greater in the South Coast Basin than
elsewhere. The attached Table 1 shows the 24-hour average and 2-hour
extreme values observed during that study. In the eastern areas of the
basin, observed two-hour highs were 71.1 ug/m3 sulfates and 247. ug/m-*
nitrates. Trajectory studies also sponsored by the California ARE
indicate that emissions from the southwestern area could be playing
a major role in contributing to such major and hazardous episodes.
Therefore, it seems to me that instead of devising control strategies
on concepts based on broad scale averaging and linearizing, success
is more readily achievable by way of a systems approach such as is
illustrated in the attached Figure 1, which includes consideration
of realistic variables.
The nationwide base of air quality to establish the history of urban
and non-urban concentrations of NOX, hydrocarbons and oxidant since
the mid 1960's is very limited and is variable in quality as a result
of limitations in instrumentation and calibration methods. The data
derived from the U. S. National Air Surveillance Network has been
criticized for poor quality and for limitations in accessibility.
The observations from many Federal, State and local agencies has been
accumulating in the National Air Data Bank, but little work has been
done on careful, detailed analysis of this collection because of a
lack of accessibility and inadequate resources of manpower and funding.
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Dr. Herbert Wiser February 4, 1975
U. S. EPA Page 3
The data base that appears to be most useful for establishing trends
in NOX and its impact on oxidant over the past ten years is that of
the Southern California area. Like other sets, these data have been
criticized for uncertainties in calibration. These have now been re-
solved by a special ARE California ARE committee on which Dr. Peter
Mueller, a co-NAS panelist, also served. The actual monitoring data
were obtained by use of essentially the same instrumentation and op-
erational methods for several years so that correction by appropriate
calibration factors now yields an internally consistent perspective.
The results from the monitoring in the Los Angeles area indicate that
center city NOX has increased with increasing emissions. In contrast,
as a result of the interaction between increased NO emissions and de-
creased hydrocarbon emissions, combined with spatial changes in emission
distributions, oxidant has deereased in central Los Angeles but increased
in areas downwind of the city, as is likely to be documented in detail
by Mr. Kinosian on your program. Such trends are not adequately docu-
mented on a nationwide basis.
There is evidence in several areas of the United States that oxidant
levels have increased, particularly in rural and suburban locations.
There is speculation that such changes are the result of ozone formed
in urban areas and transported in air parcel trajectories or widespread
increased NOX emissions combined with effects of mixtures of anthro-
pogenic and natural non-methane hydrocarbons having a wide range of
chemical reactivity in the atmosphere. Thus, the relationship between
NOX and hydrocarbons in the atmosphere is extremely complicated and
is not fully understood at the present time.
Considerable progress has been made over the past five years in im-
proving air quality models for the reactive air pollutants. The newer
prediction schemes involve calculation explicitly of the interactions
between geographical emission distributions, meteorological factors,
and atmospheric chemical processes. Because of concern for their
accuracy and their data requirements, these methods have been used
operationally only in a limited way to supplement or supersede the
classical rollback approach adopted several years ago for setting
emissions standards. There was disagreement in our panel about the
value of the simple rollback approach vs. diffusion-chemistry modeling
within its present state of development. In any case, the panel con-
cluded that the air quality modeling and data analysis has fallen far
short of those needed to establish confidence in our present national
control strategy for NOX. This is particularly distressing since
policy decisions involving a national investment of billions of dollars
have relied on an engineering analysis investment of the order 1-5
million dollars. In air history, few other technological changes have
been implemented with such a meager engineering background.
The NAS/NAE panel's original charge was not to examine the adequacy
of the current motor vehicle standards. However, at the request of
the parent coordinating committee, we attempted to evaluate the ade-
quacy of the standards to achieve the desired air quality late in the
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Dr. Herbert Wiser February 4, 1975
U. S. EPA Page 4
study. This evaluation was done with very limited resources in man-
power and time.
On the basis of a review of existing rollback calculations, it appears
that the projected NOV emission standard may be more stringent than
needed continuously to achieve the NO? ambient air quality standard
for Los Angeles. This conclusion must be qualified by (a) rollback
requires that emissions from stationary sources are reduced in pro-
portion to motor vehicle emissions, and (b) rollback will be a satis-
factory predicter of NC-2 if concentrations of this gas are proportional
to NOX emissions, and (c) there are no changes in geographical distri-
bution of sources. None of these requirements has been established in
existing analyses for any city in the United States. In fact, the
California Air Resources Board sponsored research cited earlier indi-
cates control strategies based on more realistic considerations are
likely to be more successful.
The existing rollback calculations for oxidant reduction rely heavily
on a non-methane hydrocarbon (NMHC) vapor control approach. The role
of NOX and the changes expected by shifts in NOX/NMHC ratio in oxidant
formation are considerably more uncertain than the projections for
other air pollutants. The existing analyses for the interactions of
NOy and NMHC inspire a low level of confidence for achieving oxidant
air quality using the present NOy emission projections.
The national emission standards for motor vehicles NOX + NMHC may be
overly stringent in some geographical locations, but unsatisfactory
for others, particularly where significant photochemical smog is
observed. The geographical differences in control strategy have not
been fully exploited.
In conclusion, I believe that it is clear that there are compelling
economic arguments for reconsideration of the impact on emission stan-
dards on fuel consumption and economy of transportation operations.
The present NOX emissions standards are inadequately justified on the
basis of current knowledge and experience in air quality data trends
over the past ten years. Control of pollution at the source remains
the best means for air quality improvement. However, it is necessary
now to make the detailed analytical effort to assess the degree of
NOy control required for public health and welfare commensurate with
the economic investment required for change. These engineering analyses
will require at least a year to complete and perhaps another year to
digest by policy makers.
I recommend that:
1. Careful and detailed analysis of existing information on
emissions and ambient air quality be expedited using air
quality models for key cities' potential N0£ problems or
photochemical oxidant problems.
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Dr. Herbert Wiser February 4, 1975
U. S. EPA Page 5
2. Present experimental studies in the laboratory and in the
field be expedited to provide improved information to elucidate
the interactions between NOX and NMHC in the atmosphere for
engineering applications.
3. Decisions on changing ambient air quality and emissions
standards for NOX be tempered with consideration of the long-
range air conservation needs and goals of the United States
and not be short-term economic considerations.
4. The emissions standard for NOX not be changed at this time,
but implementation be delayed for one to two years pending
the receipt of results of ongoing investigations.
A delay in implementation of NOX emission standards proposed for 1977
may be in order at this time to await the results of adequate studies
now underway or those that should be initiated. However, such delays
should be accepted knowing full well that air quality may deteriorate
further in certain parts of the nation.
The opinions expressed here are mine and do not represent those of the
Panel members, the National Academy of Sciences, or Environmental
Research & Technology, Inc.
I regret that I am unable to participate in the hearing next week.
However, I know that Dr. Mahoney will serve as an excellent substitute
for me.
If any questions emerge from the discussions that require an answer
in a communication, please let me know.
Best regards.
Yqurs sincerely,
G. M. Hidy
General Manager/WTC
GMH/mam
cc: Members of Panel
Ted Schadt (NAS/ESB)
R. Tipton (NAS/ESB)
A. P. Altshuller
Russell Train (Adm/EPA)
W. Talley (Ass't. Adm/EPA)
-------
EXPOSURE TO MAJOR AEROSOL CONSTITUENTS
(24-hour "average" /2-hour extreme)
in ^^g/mJ
SITE
South Coast Basin
A. West/Coastal
B. Central
C. Eastern
San Francisco
A. San Jose
Central Valley
A. Fresno
Non-Urban
A. Pt. Arguello
(Marine)
B. Goldstone
C. Hunter /Liggett
TCO CO*53
lor ou/j,
120/213 4.5/16.4
133/322 13.4/42.6
143/467 10.2/71.1
86.5/158 4.3/4.2
153/170 3.6/15.9
185/183 -6.5/-
42.4/42.3 1.2/-
64. O/- 2.9/-
M3~
5.2/27.3
7.6/50.2
14.7/247
5.58/
7.7/N.D.
0.98/-
1.5/-
2.1 f-
Pb C_
4.3/12.5 -/39.2
2.2/7.42 -/38.6
1.7/3.32 -/158.4
1.93/7.35
0.88/2.66
0.029/-
0.074/-
0.12/-
-------
METEOROLOGY
! EMISSIONS
Sf TIME & SPACE
OPERATE
AIR QUALITY
MODELS
1 CHEMICAL &
PHYSICAL
TRANSFORMATIONS
DEVISE
CONTROL
STRATEGIES
CONDUCT
MONITORING
DESIGN
DEPLOYMENT
DATA
/
/RE
REMOVAL FLUXES
AMBIENT
CONCN. LEVELS
RECEPTOR DOSAGES,
JUDGE
ADVERSITY
OF IMPACT
ACHIEVEMENT OP ACCEPTABLE AIR QUALITY
-------
J. QUESTIONS - COMPTON/RASMUSSEN
-------
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON. D.C. 20460
February 13, 1975
OFFICE OF
RESEARCH AND DEVELOPMENT
Dr. R.A. Rasmussen,
Associate Plant Physiologist
Air Pollution Research
College of Engineering . .
Research Division
Washington State University
/Pullman, Washington,- 99163
:;" '"' "'"' ' V . " 1 '-•!•
-Dear Dr. Rasmussen:
-•*."•• ,--j- - - i''-l"'*?v
,- *.. •»•.,«&, ~ •
.,- : Thank you for participating in the-Scientific Seminar on.'
Automotive JPollutants sponsoredjjy the S.S1. Environmental Protection.
Agency by presenting the results of your: recent field studies,
_•--; On Wednesday February 12," Mr. W. Dale Compton^of the Ford
Motor Company asked that I transmit a question to you. Mr. Compton's
question is: __ _. rr •- >-->f •'~ . •
I understood you to say that yoor^recent results
confirm an earlier independent work which stated
that any oxidant concentration greater than O.OSppta
results from anthropogenic act-jvities. If this is
correct, doesn't this mean that with a natural back--
ground value of O.OSppm it will he physically
impossible to achieve the primary Air Quality Standard .
, of O.OSppm, for oxidant? Would yctu also "please enter
--•;<% .into; the recprd the reference _to the earlier work which-.,.
; _.-,- you gave?.,- W. Dale Compton, Baxd Hotor Company.
: "I would appreciate your responding to Mr, Compton directly with
a copy to me for the record. Again,?!" thank you for participation
and commend your;excellent research.. . "-.r „
•_£_. ( Sincerely.yours,
Herbert E. Wiser
^ .Deputy Assistant Administrator
for Environmental Sciences <
-------
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
February 24, 1975
or rice OK
nr'-,FARCH AND OEVFLOPMFN T
Dr. James Mahoney
Environmental Research and Technology, Inc.
696 Virginia Road
Concord, Massachusetts 01742
Dear Dr. Mahoney:
Thank you for participating in the Scientific Seminar on Automotive
Pollutants sponsored by the U.S. Environmental Protection Agency by
presenting the National Academy of Sciences viewpoint on the NOx-
Oxidant-NO problem.
During the seminar Mr. W. Dale Compton of the Ford Motor Company
asked that I transmit a question to you. Mr. Compton's question is!
I was interested in your answers to a question which indicated
that much of the concern of the NAS Committee study was related
to the smog problems of the Southern California Basin. If the
conclusions of the study are to be taken as primarily related
to the California basin, does it therefore follow that the
Committee felt that the most acceptable VES (Vehicle Emission
Standards) would be represented by a two car strategy wit:h the
49 state VES being less stringent than that proposed in the
report?
I would appreciate your responding to Mr. Compton directly with a
copy to me for the record. Again, thank you for your contribution to
the seminar.
Sincerely yours,
Herbert L. Wiser
Enclosures
Deputy Assistant Administrator
for Environmental Sciences
-------
DR JAMtS H MAHONIY
Vcu PiustcJnnt iiiuJ Fuchnioal LJuci.toi
Reference: JRM-63
26 February 1975
Dr. W. Dale Compton
Vice President for Scientific Research
Ford Motor Company
20000 Rotunda Drive
Dearborn, Michigan 48121
Dear Dr. Compton:
During the Scientific Seminar on Automotive Pollutants sponsored by the U. S.
Environmental Protection Agency, I presented the National Academy of Sciences'
viewpoint on the N0x-Oxidant-N02 problem. At the conclusion of my presenta-
tion you forwarded the following question:
"I was interested in your answers to a question which indicated that
much of the concern of the NAS Committee study was related to the
smog problems of the Southern California Basin. If the conclusions
of the study are to be taken as primarily related to the California
basin, does it therefore follow that the Committee felt that the most
acceptable VES (Vehicle Emission Standards) would be represented by
a two car strategy with the 49 state VES being less stringent than
that proposed in the report?"
My response to this question follows:
1) In my oral response to the question I did indicate that the
majority of the NAS panel had specific experience with the
smog problems of the Southern California Basin. However, I
also indicated that the panel specifically considered the
need to offer advice for the entire nation, and not only
for the Southern California region.
2) The NAS panel did consider the two-car strategy and felt
that the strategy should be examined in greater detail.
However, the panel did not make a specific recommendation
concerning the two-car strategy.
-------
Dr. W. Dale Compton
Page 2
3) On the basis of substantial technical and professional ex-
perience, both Dr. Hidy (who chaired the NAS panel) and I
feel that the two-car strategy should definitely receive
intensive study. As our panel report indicated, the data
base for the national policy decisions on automotive emis-
sion controls is very limited. A two-car strategy must be
.considered as an attractive control operation in terms of
(1) achieving compliance with the National Ambient Air
Quality Standards in all urban regions of the country and
(2) efficient use of energy and financial resources. The
data base presently available for evaluation of two-car
strategies is very much improved compared to the informa-
tion available during the period when the 1970 amendments
to the Clean Air Act were being drafted and debated.
If you desire further information, please let me know.
Sincefely,
James R. Mahoney
Vice President and
Technical Director
JRM.-BQH
cc: VDr. H. L. Wiser, EPA
Dr. G. M. Hidy, ERT
bcc: N. E. Gaut
J. S. Kent
E. Newman
P. E. Sherr
R. A. Stauffer
O9O VIRGINIA ROAD. CONCORH. MAS.SAC.I UJSf I IS O1;/K> (617) 3GO R<)K
-------
WASHINGTON STATE UNIVERSITY
PULLMAN, WASHINGTON 99163
DEPARTMENT OF CIVIL AND ENVIRONMENTAL ENGINEERING
March 11, 1975
Dr. Herbert L. Wiser
Deputy Assistant Administrator
for Environmental Sciences
United States Environmental
Protection Agency
Washington, DC 20460
Dear Dr. Wiser:
In reply to the question raised by Dr. Dale Compton of Ford Motor
Company on Wednesday, February 12, I have the following reply:
Dear Dr. Compton: The earlier independent work that I referred to in my
talk, that had concluded that any oxidant concentration greater than
0.08 ppm results from anthropogenic activities, was a specific reference
to the conclusions by Ripperton, Jeffreys and Worth in their paper
entitled "Relationship of Measurements in Nonurban Air to Air Pollution:
Namely Ozone and Oxides of Nitrogen," published in the Proceedings of
the Second International Clean Air Congress in 1970.
Your suggestion that the statement infers that, with a natural background
value of 0.08 ppm, it will be physically impossible to achieve the
Primary Air Quality Standard is a reasonable conclusion derived from the
statement alone. However, the data we have on background surface ozone
levels measured within the United States in rural sites suggest that
0.08 is the upper limit of the natural ozone level. It is not possible
to unequivocally exclude 0.08 ppm of ozone as not resulting from the
natural ozone sources in the lower troposphere. Under such conditions
it would be very difficult to achieve the standard.
Sincerely,
R. A. Rasmussen
Professor
Environmental Engineering
Air Pollution Research
RAR:tt
-------
K. HEALTH EFFECTS CRITIQUE
-------
SUMMARY OF HEALTH STUDIES PRESENTED
AT THE EPA SEMINAR
"Health Effects of Automotive Pollution"
IDuring this Scientific Seminar on Automotive pollutants, 18
papers were presented and discussed. For the rest part, the
presentations v/ere related to nitrogen oxides.
Conclusions
f--. Evidence presented at these hearings contains scrr.e recent
scientific thinking which may-have a bearing on administrative
decision-making. It does not, however, represent an exhaustive
jj-vijy/ of all.-extant data on the "Ox prcbiei.i, nor the CO and
'oxidant problems. Opinions of scientists presenting papers at
;_
this seminar cannot be taken _a_s fully representing all sectors of
-the scientific..community. Results and apparent opinions are
summarized in-the attached table with this understanding.
Regarding the delay or relaxation of the NOx standard, it
appears that two fundamental considerations must be recognized.
first, any basis for a decision of this nature rust take into
account the health importance of short-term, peak f!0x
concentrations in the atmosphere, _ar.d must consider both
stationary and mobile sources. ' ;
-------
There has been recent recognition that short-tern, peak
exposures £lay an important role in the appearance of adverse
health effects. Jn this connection, these health considerations
point to the need for a strategy to limit short-tern excosures.
Hhile it is essential to continue existing control of long-tern
exposures, ccnipler.enting them with measures to lirrit short-term
exposures also seetr.s warranted. -...-. -.. . ...u._"... . . • .:
- •• The second-.fundamental consideration v,'hich surfaced refers to
the fact that EPA is confronted vrith indications that N02
"'transformation products, jfor which standards have not been set, •.
may be associated vn'th adverse health effects. '_Tn the absence of
'fully definitive data to assess the health impact of increasing
these products by increasing KG?, emissions, it v/oulc! be prudent
to maintain the mobile source KQx standards at least within the
• range 0.4-2.0 grer.s _p_er mile until ir.ore precise data_can be
-^obtained. An exact value within this range would, of course,
'depend in part on the existing and anticipated degree of
stationary source MOx control.' . ••-:.- ' " • '
i- D_ata presented on CO generally suggest that the current
' standard is adequate vn'th respect to health considerations.
. • «<
Although health information or, cxidants v/as linited, it
''Appeared that h_ealth effects observed in relation to ozcr.e
-------
SFEAKCP.S OPIN'ICXS UGAKOiNG STANDARDS*
t.'Cr
Wants More Supports
Stringent Present
' • ' • Stnio'ords Stondnrd
Wants Wants Don't Want Nor
Short-term Standards Any Ccnva!
• jtnn'iard Related Standnrd
'Itt; (University of California - Riverside) ' • ' - :*,'. ' "-*; '' x . x
:ed-:r.J (S'o.'or.il Acac/;r.y of Sciences) • . • x x
hy Co''.!
O-'!.I"!T
ro.n (.
c"a rl,ii,
r 1 i c ;; (
arc.", or
: n t e r -i
M, ' c i n
!;i;-; 1
icr .', n
ic1 son
i ^ ,.,. ,j ^ (
3df,rd
3,-, Jtl.
v:r :,! ty of North Corcll'ia) ' . , . x X
1 (P'l'jllc Intercit Ceupaljn ; ,'. x '.;, • •'' ' •':','•. . .. ;•';,. x
r '' v>it e C 1 t ! f.n
• ' • ' • •'••-• ' .. '.'' ;. x
.! (-.il fOM Corpor.it Ion) • ' • • •
- - ' • X
1 ! i Inolu Ins t 1
Crv!(o.n-,,..Tt3|
( ! i 1 1 .-. . i c 1 .- , t
(Cj'.v '.'-',',trn 1
':••;- e Unlvcrult'
1'J.t' ver 5l ly of
(Cnvlv.n,= ntal
!'..;.Jk.:l Co!!e<
( J'. ',r, 5 'lop!-, ins
{ixi Ivors I ty of
lute of Tfchnolo'jy , Inc. .,••'. >
Protection Agency - RTP) x x
Itule of Technology Research, Inc. . x x
n,e;erv.- Unlvt.rifty) x
/) x x
California - L.A.) • x x
• • ro
Protection Agency - RTP) X
rje of V/! sconsln X
Unl verj 1 ty
Cj 1 1 fornla x
iclson {environmental Protection Agency - RTP)
Ozorc
•rhesc opinions were deo'ufctc.d by staff fro,ii the papers given or frcxn answers given to questions from the floor.
i
-------
exposure v/culd tend to support _the notion that increased exposure
to this pollutant above that currently allowable is undesirable.
Results
«-,,— --...- .—..-......• i
During the overviev/ presentation and discussion on KOx,
several general but nevertheless important ccnclusions emerged.
First, in considering the health implications of nitrogen
dioxide, j_t nust be recognized that multiple chemical and
physical interactions and meteorological conditions conbins to
produce a_ complex of nitrogenated compounds, not to irention other
£ollutants,-for-which standards have not been established, Ttiese
nitrogen compounds, having health implications„ nay include
pir^ s\i-t fpf- y"t pi-f-^pfr, •, p -? ^,-fv-.-!r ;,r,,! r''1'-r.i"- -.,•-'/! •' -t -%'!'!• *- i r-^ i-r,
I » , , , ,j ^L,<- u^' ; It . .-r C« i« I ,v. i :r!»: I ^. C, i . ' I i I '. i L> WJ ~> C. L I U 5. ! !i U J vi i %, i 01 I tO
1.0 end K02. j^itrosarr.ines, v;hich have carcinogenic properties,
have also been suggested _a_s possibly being linked to NOx
transformation processes. j_n -the Los Angeles basin, it has been
estimated that 50% of the suspended aerosols are of secondary
origin, that is, they are the result of atmospheric
transformation processes. Tracer studies show that these
pollutants ray drift from region to region, generally in an
eastward direction. During transformation or conversion
processes, aerosol particles'of subnicron dimensions _are •
generated. Particles in this size range are r?st significant to -•-
visibility cegradation and to adverse health effects.
-------
It v/as noted that stationary as well as mobile sources
~ibute to nitrcgen oxide loading in the atrcsphere. _Tt v.-es
rated tha~ in the Los Angeles basin, if the current ^Cx
,rol prcgran for mobile sources is carried out by 1920 or the
y 80's, stationary sources will contribute as r.uch to ^Ox
h'ng as will irobile emissions. Coal corrbusticn in stationary
•ces represents a significant contribution jto total NOx .
;s1on, •••. ''...'."''--
B_ased on single, 10-45 minute exposures to N02 in humans, it
Calculated that an adverse response as indicated by
n'ficantly decreased a_irv/ay resistance could be expected v.'ith
yle, 1-hour maximum N02 exposures _of 0.40 - 1,33 ppm.
:?ptiblc populations could be expected to resporid to ihe lov/er
of this range> or at apprcxirr.ately 0.40 - 0.50 ppn. Animal
human data suggest that resistance to respiratory infections
be impaired and lung damage may occur with repeated, short-
•n exposures to 0.15 - 0.50 pprn N02. _Susceptible individuals
ild be likely to respond at approximately 0.15 - 0.30 ppn j_!Q2.
A_ riaxinurn allowable one-tine, one-hour N02 exposure can
srefore be Calculated as 0.20 - 0.34 ppm, based on protecting
.3ccjpt:!:le individuals _a_nd providing a rargin of safety of
proxir.-'tely 2. An analogous calculation ray bo race for
xir-'.-n allowable repeated, short-tern exposures as 0.03 - 0.20
-------
pprn. It should be recognized that these estimates do ret j_r.clud=
the potential for adverse effects v.'hich rr.ay be associated v/ith
N02 transformation products.
i
To achieve the above exposure limits for short-tern fiC2
concentrations, a_n f!Qx emission standard in the range of 0.£ -
2.0 grarr.s per nile has been projected. It has been stated that
there is no reason to believe that an NOx emission standard above
2.0 grams per mile would achieve the indicated range of exposure
limits. The exact emission standard required to insure that 1-
hour ambient concentrations _dp not exceed 0.20 - 0.34 ppn would
ba determined in part by the extent to which stationary source
hOx is controlled. ' •
It was pointed out that a recent EPA analysis of the impact
of relaxing the statutory r.obile source f.'Ox standard is based
upon the current ar.bient air quality N02 standard. Since the
ambient standard j_s given only as an annual average, .
considerations of potential short-term peak exposure jvere net
included, and therefore this assessment of the FI02 situation may
have underestimated the magnitude of the IIOx problem in U.S.
cities.
rf
Hhile the absence of adequate r.easurenent pet-scds _fcr .".'Ox do
not fully pc-rnit the precise- quantitative results jvhich are
-------
unu ir.caei snc-'.nncr th?.t ircreised
Mstanin.e, a known broncho-constrictor, is released \::;n exposure •
to armors i urn nitrate or arr.oniun sulfate, components cf suspended
fine participates. Another health effect mentioned, v.-hlch iray
result from exposure to either .-102 alcne or in ccr.bi nation v/ith
other atmospheric jopllutants, v;?.s that of chronic respiratory
disease, i.e., chronic bronchitis or ejnphyserr.a, ' •
","•**•- - • -
The data presented on health effects from ozone v/ss based
pj-inarily en controlled exposure studies in humans. These
studies looked at certain £hysiological parameters before and
after exposure to 0.4 pp.^ of ozone for four hours. A_ highly
statistically significant decrement ,v/as observed j_n the ability
of human peripheral neutrophils to phagocytize k_ncv/n doses of
bacteria. Sisrrificar.tly increased chrorr.atid breaks v.sre
observed, a_s v;ere significant decreases _in pulrcnary function.
/\11 of these functions returned to basolina levels. 4 weeks after
of exposure. • '• :
J_he studies presented showed that exposures to CO ranifest
themselves in a variety of responses. J_n controlled, huran
studies of exposure to CO resulting j_n carboxyher-c-plcbin levels
of approximately 4.5 - 5.0;i, a marked reduction occurred rn both
the capability for physical v;ork and in cental vigilance. Aninal
*
studies on the effects of CO showed a decrement in cardiovascular ••
-------
rfornance as measured by EKG changes, population studies
dicatcd that a decrease in carboxyheroglobin .levels from 1370
1974 v.'as compatible viith a decrease in ajr.bient CO roasurcront
the con.munity studied.
-------
Dr. A. P. Altshullcr . : '
National Environmental Research
Center
Chemistry and Phtsics 'Laboratory
Research Triangle Park, N. C. 27711
Dr. Bruce Bailey V: • ''
P.O. Bo." 500 '
Beaho.% 1\.Y. 12500
i «
Dr. -Alan Bandy
Chemistry Department
O;d Dominion University
V -c X ^ O C) U O
•Dr. Billings Brown
"'3501 South 3G50 East
Salt Lake City, Utah 84109
• Dr. Basil Dimitriades
National Environmental Research
Center
Chemistry and Phvsics Laboratory
Research Triangle Park, N. C. 27711
Dr.. Clarence Ivl, Di^ov ITT.
Public Interest Research Group
2000 P Street, N.W.
Suite 711 -- •--••-....-
Washington, D. C. 2C03S
Dr. James Edingcr
Department of Meteorology
University of California
L-os Angeles, California 90024
Dr. Richard Ehrlich
IITRl
50 West 35th Street
Chicago, Illinois 60616
Dr. Samuel Epstein
Sv/etland Professor of
• Envi.ro:;mental Health and
Human Ecology
School of Medicine
d se Western Reserve University
Cleveland, Ohio 44106
D,% Jamer- "Tenters
10 V-r' 'i t 3 5' i • c-1>- --- ^+
C'icago, i'll:r.o:p C0316
Dr. Jean French
National Environmental Research
•-' Center
Human Studies Laboratory
.Research Triangle Park, N. C. 277
Dr. Donald Gardner
Kaiional Environmental Research
Center
Experimental Biology Laboratory
Research Triangle Park, N. C.' "277
. Dr. Thomas Graedel
Bell Telephone Laboratory
Room ID 349
Murray Hill, New Jersey 07974
Dr. Thomas Hecht
Systems Application Inc.
850 Korthgate Drive
San Rafael, California 94903
Dr. Jon Ileus s
General Motors Research
Laboratory
GM-Technical Center
Warrea, Michigan 4S090
Dr. Steven Horvath
Institute of Environmental Stress
University of California
Santa Barbara, California 93105
Dr. John Kinosian,
1709'llth Street
Sacramento, California 95814
Dr. Beat Kline r
Bell Telephone Laboratory
Murray Hill, Ncv/ Jersey 07974
Dr. John Knelso::
'National En vii _____ ;...•.•:: ".'.-.-c.'-i-c;;-
Center "^
Him an Studies I.oboratury
Research Triangle Park, N. C. 2
Mr. Louis Lombardo
0711 :,li.A:-ii:;:r i;ivd.
2003-*
-------
:>. James Mahoney
r/ironmental Research and
''echnolcoy, Inc. • • -•--.
Virginia- Road • •-" •'.
,ncord, Massachusetts 01742
\ Daniel Menzel - • >->
0. Box 3709
he University
•nU-,->-> AT p 97 7 ID
1. lliLlitf . 1\ . >^« £• > I J-\J
, -James Pitts
iversity of California
rerside, California 92502
, Ecnvard Radford
•>artment of Environmental Medicine
ool of Hygiene and Public Health
3 Johns Hopkins University
• North V/olfc Sireet
Urn ore, Ivlaiyland' 21205 •
R.; i. R a s m u r- a e n
ocicite Pia:it Piiysiologist - • •..
]-'ollution Research
letrje of Engineering
;earch Division -
•;hington Stale University
Irnan, Washington S9163
, John Redmond
•oncJ. Academy of Sciences
1 Constitution Avenue, N. W.
3liinf;ton, D. C, 20418
Dr. R. A. Saundera
Code 6110
Naval Research Lab
.Washington, D. C. 20375 ;'.
Dr, Russell P. She r win -
Department of Patliology
School of Medicine
University- of Southern California
2025 Zonal Avenue
Los Angeles, California 90033
Dr. Carl Shy'
institute for Environmental Studies
University of North Carolina
Chapel Hill, N. C. 27514 "
Dr. Chet Spicer - -
Battclle, Columbus Laboratories
505 King Avenue
Columbus, Ohio 43201
Dr. 'Richard Stev/art
Allen Bradley Medical Sciences .
Laboratory
KcGzorl C:.llc.je of Wisconsin
8YOG West Wisconsin Avenue
Mihvaukee, Wisconsin 53225
Harold McFarlar.d
Oil Corporation
ccl Depatrrent
Pa. 15230
------- |