PB81-200628
ATMOSPHERIC MEASUREMENTS OF SELECTED HAZARDOUS
ORGANIC CHEMICALS.
SRI International
Menlo Park, California
May 1981
U.S. DEPARTMENT OF COMMERCE
National Technical Information Service
-------
EPA-600/3-81-032
May 1981
PB81-200628
ATMOSPHERIC MEASUREMENTS OF
SELECTED HAZARDOUS ORGANIC CHEMICALS
Interim Report - 1980
by
H. B. Singh
L. J. Salas
A. Smith
R. Stiles
H. Shigeishi
Atmospheric Science Center
SRI International
Menlo Park, California 94025
Cooperative Agreement 805990
Project Officer
Larry Cupitt
Atmospheric Chemistry and Physics Division
Environmental Sciences Research Laboratory
U. S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
ENVIRONMENTAL SCIENCES RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U. S. ENVIRONMENTAL PROTECTION AGENCY
RESEARCH TRIANGLE PARK, NORTH CAROLINA 27711
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completinp'
1. REPORT NO.
EPA-600/3-81-032
2.
3. Rl
4. TITLE AND SUBTITLE
ATMOSPHERIC MEASUREMENTS OF SELECTED HAZARDOUS
ORGANIC CHEMICALS
Interim Report - 1980 '
5. REPORT DATE
May 1981
6. PERFORMING ORGANIZATION CODE
P881-200628
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
H. B. Singh, L. J. Salas, A. Smith, R. Stiles, and
H. Shioeishi
SRI Project 7774
9. PERFORMING ORGANIZATION NAME AND ADDRESS
SRI International
333 Ravenswood Avenue
Menlo Park, California 94025
10. PROGRAM ELEMENT NO.
C9TA1B/01-Q352
11. CONTRACT/GRANT NO.
CA805990
12. SPONSORING AGENCY NAME AND ADDRESS
Environmental Sciences Research Laboratory-RTP, NC
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park. North Carolina 27711
13. TYPE OF REPORT AND PERIOD COVERED
T n't" ov* 1 m
14. SPONSORING AGENCY CODE
EPA/600/09
15. SUPPLEMENTARY NOTES
Previous Report: EPA-600/3-80-072
16. ABSTRACT
Methods were developed for the accurate analysis of an expanded list of hazardous
organic chemicals in the ambient air. On-site analysis using an instrumented mobile
laboratory was performed, for a total of 44 organic chemicals. Twenty of these are
suspected mutagens or carcinogens. Toxicity studies for several others are currently
pending. Six important meteorological parameters were also measured. Four field
studies, each about two-weeks duration, were conducted in Houston, Texas; St. Louis,
Missouri; Denver, Colorado; and Riverside, California. An around-the-clock measure-
ment schedule (24 hours per day, seven days a week) was followed at all sites, per-
mitting extensive data collection. Widely varying weather conditions facilitated
observations of pollutant accumulation and wide variabilities in concentrations of
pollutants at a given site. Concentrations, variabilities, and human exposure (daily
dosages) were determined for all measured pollutants. The diurnal behavior of
pollutants was studied. Average daily outdoor exposure levels of all four sites
were determined to be 197 yg/day for halomethanes (excluding chlorofluorocarbons), 140
yg/day for haloethanes and halopropanes, 89 yg/day for chloroalkenes, 32 yg/day for
chloroaromatics, 1,394 yq/day for aromatic hydrocarbons, and 479 yg/day for secondary
organics. Exposure levels at Houston, Denver, and Riverside were comparable, but
levels were significantly lower at St. Louis.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
18. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (TMs Report/
UNCLASSIFIED
21. NO. OF PAGES
20. SECURITY CLASS (This page)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (R«v. 4-77) PREVIOUS EDITION is OBSOLETE
I
-------
DISCLAIMER
This report has been reviewed by the Office of Research and
Development, U.S. Environmental Protection Agency, and
approved for publication. Approval does not signify that the con-
tents necessarily reflect the views and policies of the U.S.
Environmental Protection Agency, nor does mention of trade
names or commercial products constitute endorsement or recom-
mendation for use.
n
-------
ABSTRACT
During the second year of this project, methods were developed for the
accurate ambient analysis of an expanded list of hazardous organic chemicals.
On-site analysis using an instrumented mobile laboratory was performed for a
total of 44 organic chemicals. Twenty of these are suspected mutagens or
carcinogens. Toxicity studies for several others are currently pending. Six
important meteorological parameters were also measured. Four field studies,
each of about two-weeks duration, were conducted in Houston, Texas; St. Louis,
Missouri; Denver, Colorado; and Riverside, California. A round-the-clock
measurement schedule (24 hours per day, seven days a week) was followed at all
sites, permitting extensive data collection. Widely varying weather condi-
tions facilitated observations of pollutant accumulation and wide variabili-
ties in concentrations of pollutants at a given site. Concentrations, varia-
bilities, and human exposure (daily dosages) were determined for all measured
pollutants. The diurnal behavior of pollutants was studied. Average daily
outdoor exposure levels of all four sites were determined to be 197 yg/day
for halomethanes (excluding chlorofluorocarbons, 140 yg/day for haloethanes
and halopropanes, 89 yg/day for chloroalkenes, 32 yg/day for chloroaromatics,
1,394 yg/day for aromatic hydrocarbons, and 479 yg/day for secondary organics.
Exposure levels at Houston, Denver, and Riverside were comparable, but
levels were significantly lower at St. Louis.
-------
CONTENTS
Abstract iii
Figures vii
Tables ix
1. Introduction 1
2. Overall Objectives 3
3. Second-Year Research Summary 5
4. Analytical Methodology 9
Trace Constituents of Interest 9
Field Instrumentation 11
Experimental Procedures. 13
Calibrations 15
Quality Control 19
5. Plan of Field Measurements 21
6. Analysis of Field Data 23
Atmospheric Abundances, Daily Exposures,
Fates, and Variabilities of Measured Species 23
Data Analyses by Chemical Category 25
7. Future Research Plans 49
Reference s 51
Preceding page blank
V
-------
FIGURES
Number Page
1 Permeation tube weight-time relationship
for selected chemicals 17
2 Location of field sites during the second year 22
3 Atmospheric concentration of methyl chloride 27
4 Atmospheric concentration of methyl bromide '. 28
5 Mean diurnal variation of methyl iodide 29
•
6 Mean diurnal variation of methylene chloride 30
7 Atmospheric concentration of methylene chloride
at Riverside, CA, 2-12 July 1980 31
8 Atmospheric concentration of chloroform
at Riverside, CA, 2-12 July 1980 32
9 Atmospheric concentration of carbon tetrachloride 32
10 Atmospheric concentration of ethyl chloride 33
11 Mean diurnal variation of 1,1 dichlo roe thane 34
12 Atmospheric concentration of 1,2 dichloroethane. 34
13 Mean diurnal variation of 1,2 dichloroethane. 35
14 Atmospheric concentration and mean diurnal variation
of 1,2 dibromoethane at Denver, CO, 16-26 June 1980 36
15 Mean diurnal variation of 1,1 trichloroethane 37
16 Mean diurnal variation of 1,1,2 trichloroethane
at Riverside, CA, 2-12 July 1980 38
17 Mean diurnal variation of 1,2 dichloropropane
at Riverside, CA, 2-12 July 1980 39
18 Mean diurnal variation of trichloroethylene 40
19 Mean diurnal variation of tetrachloroethylene 41
20 Mean diurnal variation of monochlorobenzene
at Denver, CO, 16-26 June 1980 42
21 Mean diurnal variation of m-dichlorobenzene
at Denver, CO, 16-26 June 1980 42
Preceding page blank
vii
-------
Number Page
22 Mean diurnal variation of 1,2,4 trichlorobenzene
at Riverside, CA 2-12 July 1980 43
23 Mean diurnal variation of benzene 45
24 Mean diurnal variation of toluene 46
25 Mean diurnal variation of m/p-xylene
at Houston, TX, 15-24 May 1980 47
26 Atmospheric concentrations of formaldehyde 47
27 Mean diurnal variation of peroxyacetyl nitrate (PAN)
at Riverside, CA, 2-12 July 1980 48
viii
-------
TABLES
Number Page
1 Concentration, Daily Exposures, and Toxic Effects
of Measured Hazardous Organic Chemicals 6
2 Average Daily Outdoor Exposures to Hazardous
Organic Chemical Groups 7
3 Target Chemicals for Second-Year Research 10
4 Estimated Unit Risk Factors for Selected Carcinogens 11
5 Environmental Mobile Laboratory Instrumentation 12
6 Analytical Conditions for the Analysis
of Selected Toxic Chemicals 14
7 Permeation Rate Data for Generating Primary Standards 16
8 PPM Primary Standards in Air 18
9 Concentrations and Daily Exposures of Measured
Chemical Species 24
10 Summary of Exposure to Hazardous
Organic Chemical Groups 25
ix
-------
SECTION 1
INTRODUCTION
A vast number of potentially harmful organic chemicals are released into
the environment, and it is becoming increasingly apparent that these chemicals
contribute to the growing rate of cancer in industrialized countries. Despite
recent and intense interest in toxic chemicals, the atmospheric abundance and
fate of this important group of pollutants remains poorly understood. The
purpose of this study project is to characterize the concentrations of a wide
range of toxic organic chemicals at several urban and source-specific loca-
tions under varying meteorological and source-strength conditions. The mea-
surement of these toxic chemicals is being conducted by in-situ analysis of
ambient air using a suitably outfitted mobile laboratory. The overall program
of analytical methods development, field measurements, data collection, and
analysis is expected to provide information that will permit determination of
the atmospheric abundance and chemistry of this potentially harmful group of
chemicals.
The research plan is primarily designed to answer the following basic
questions:
• What are the concentration levels and variabilities of selected toxic
organic chemicals in typical urban environments?
• What are the atmospheric fates of these chemicals?
• What is the extent of human exposure to selected toxic chemicals?
The answers to these questions will be sought through a combination of
approaches:
• A comprehensive program of field measurements at several urban loca-
tions and near several source-specific locations.
• Analysis of data collected during the field measurements and integra-
tion of this information with data acquired from outside sources.
• Compilation of all available information dealing with the sources,
sinks, chemistry, and effects (health as well as environmental) of the
toxic chemicals of interest.
This summary report presents the results accomplished during the second year
of a three-year research effort. Analysis of data collected during the second
year is by no means complete: Additional analysis will be presented in forth-
coming reports and publications.
-------
SECTION 2
OVERALL OBJECTIVES
The overall objectives of the proposed study are to:
• Characterize the abundance and variabilities of selected toxic organic
chemicals in urban environments.
• Investigate and assess the atmospheric fates (sources and sinks) of
these toxic chemicals.
• Determine the extent of human exposure.
To achieve these objectives, SRI will use the following approach:
• Develop and standardize new and improved procedures for sampling and
analyzing toxic chemicals.
• Measure the atmospheric concentrations of toxic chemicals at several
representative locations to develop a valid data base for ambient lev-
els of toxic chemicals, and use these measurements to better under-
stand the atmospheric fates of these chemicals.
• Update, validate, and assimilate information of production, emissions,
atmospheric abundance, fates, and effects of toxic chemicals based on
a continued program of literature search and information gathering.
• Develop and synthesize information on sources, removal mechanisms,
extent of exposure, and health effects suggested by the preceding
tasks.
Preceding page blank
-------
SECTION 3
SECOND YEAR RESEARCH SUMMARY
The second-year research effort comprised a program of analytical methods
development, field-data collection, data processing, and data interpretation
for an expanded set of hazardous organic chemicals. All field measurements
were conducted in-situ with the help of an instrumented mobile laboratory.
After completion of the program of methods development, four field studies of
roughly two-week duration each were conducted in Houston, Texas (Site 4); St.
Louis, Missouri (Site 5); Denver, Colorado (Site 6); and Riverside, California
(Site 7). These field studies were completed between early May and late July
of 1980. The studies were designed to complement the three field studies con-
ducted during the first year of this project at Los Angeles, California (Site
1); Phoenix, Arizona (Site 2); and Oakland, California (Site 3). Continuing
practice of the first-year research, all field work in the second year was
performed on a round-the-clock basis (24 hours per day, seven days a week),
permitting the efficient collection of a large amount of data. A total of 44
organic chemicals and 5 meteorological parameters were measured. Over 20 of
these chemicals are either mutagens or suspected carcinogens; in many other
cases toxicity studies are currently incomplete.
Table 1 summarizes the average concentrations measured at each of the
sites and the daily average outdoor exposure based on a total air intake of 23
m-Vday for a 70 kg male. The corresponding standard deviations associated
with these parameters are shown in Table 1. The mutagenicity and toxicity
information for individual species is also summarized in Table 1. It is per-
tinent to note that roughly 90 percent of mutagens are found to be carcinogens
(McCann and Ames, 1977). Table 2 summarizes average exposure (//g/day) to
individual categories of chemical groups at each of the sites. Overall, the
total exposure to measured toxic chemicals at Houston, Denver, and Riverside
was comparable (it was significantly lower at St. Louis). As a category,
exposure to aromatic hydrocarbons is the highest, and to chloroaromatics the
lowest, at all sites.
Hot-spots for specific toxic chemicals are found at different locations.
As is clear from Table 1, the ambient levels of 1,2-dichloroethane (a sus-
pected carcinogen) were significantly elevated at the Houston site despite
meteorological conditions that were unfavorable to pollutant accumulation.
Hot-spots of methylene chloride (a weak mutagen) and chloroform (a suspected
carcinogen) were observed at Riverside. The high concentrations of chloroform
at Riverside are surprising. (No large sources are known.) Special tests were
conducted to ensure the reliability of these data: Chloroform data were found
to be accurate to within ±10 percent. Formaldehyde, another suspected carci-
nogen, was measured at high concentrations at all sites.
Preceding page blank 5
-------
TABU t. CONCtNIHAllONS, DAILY EXPOSURES. A NO TOXIC EFFECTS
OF MfcASUHEU HAZARDOUS ORGANIC CHEMICALS
Chemical Gioup md SptCiM
Chtot otluot OCMirMn«
1.1.7.2. r«HKhlorotthMM
1.2 Oichtofop»a*Mn«
CMoio«lk*iwt
V.nyttd*n*> cMorid*
Icn) 1.7OKhlo>Dethyt«M
T» ktllo* o« ih y taw)
TaiiAchlotocthvtaM
Allyl chkMHte
H.IMh1 toJtwtt
1.7.4 tiinMihyl bennnt
1.3.5 Tumcthyl foment
°"Tr^^r*
flmupn*
P*'i>.v*C,mtmi«i«g* ••POM'* tMMil act tout •>< inuh* at 23 mj/d*» ml 2b°C *nd t am i
*8M B«cim«t Mtdaotn; Poiilivc mulaymtt Ktivily b«Mcl on Amtt Mlmonvll* ntuldgc
NBM (Not Bacuii*! Muiigcn) NC««|IM lenxinM in Ihe Amn i«tmonaltj mut»0>niciiy
SC Sinp«clEd
-------
TABLE 2. SUMMARY OF EXPOSURE TO HAZARDOUS
ORGANIC CHEMICAL GROUPS
Chemical Category*
Chlorofluorocarbonst
Halomethanes
Haloethanes and
halopropanes
Chloroalkenes
Chloroaromatics
Aromatic hydrocarbons
Oxygenated species
Total Average Daily Exposure (jig/day)
Houston -
Site 4
205
203
210
88
37
2130
-
St. Louis -
SiteS
141
97 -
59
78
25
430
344
Denver -
Site 6
241
168
137
92
34
1616
396
Riverside -
Site 7
262
319
153
98
-
1401
696
Average
of Sites
212
197
140
89
32
1394
479
*As defined in Table 1
tNOT suspected to be directly toxic
To the extent that urban data can act as an early warning indicator of
emissions, it appears that the use of fluorocarbon 113 has significantly
increased. Typical fluorocarbon 12 and fluorocarbon 113 ratios are 1/2 to 1/3
of what should be expected, based on known emission information.
In order to assess the atmospheric fates of measured toxic chemicals,
mean diurnal variations of these substances were studied at each of the sites.
These results are discussed in the text. It is clear, however, that the
atmospheric abundance of hazardous organic chemicals at a given site can vary
by an order of magnitude or more depending upon the source strength, chemical
lifetime, and the prevailing weather conditions. The spectrum of chemicals
measured is very similar in all urban atmospheres, although exposures can vary
significantly.
-------
SECTION 4
ANALYTICAL METHODOLOGY
TRACE CONSTITUENTS OF INTEREST
The target chemicals that were measured during the second year of
research were those suspected of being hazardous or chemicals structurally
similar to these. In many cases, toxicity data are currently unavailable or
pending. Our ability to satisfactorily measure a trace constituent at its
expected ambient concentration was also an essential requirement for its
inclusion in this work. No data are reported on p-CfclfyC^ because atmospheric
interferences prevented rigorous quantification. Preliminary efforts were
also made to measure acrylonitrile in the ambient environment; however, this
attempt was abandoned after we concluded that existing measurement methods are
unsuited for ambient analysis.
A total of 44 trace chemicals were targeted and are categorized in Table
3. The categories include chlorofluorocarbons, halomethanes, haloethanes,
halopropanes, chloroalkenes, chloroaromatics, aromatic hydrocarbons, and oxy-
genated and nitrogenated species. The chlorofluorocarbons are considered to
be nontoxic but are excellent tracers of polluted air masses. - Formaldehyde
was the only aldehyde measured, although work is in progress to develop mea-
surement methods utilizing liquid chromatographic techniques for other ali-
phatic and aromatic aldehydes. A number of important meteorological parame-
ters (wind speed, wind direction, temperature, pressure, relative humidity,
and solar flux) were also measured.
It is obvious from Table 3 that a large number of targeted chemicals are
either mutagens or suspected carcinogens (Helmes et al., 1980). It is per-
tinent to add here that 90 percent of the mutagens are found to be carcinogens
and 90 percent of noncarcinogens are found to be nonmutagens (McCann and Ames,
1977). Assuming a nonthreshold carcinogenic response, unit risk factors for
several carcinogens can be determined. A unit lifetime risk factor (f) is
obtained by extrapolating animal bioassay data to humans. The risk factors
computed for a healthy male (70-kg weight) when exposed to 1 ^g/m^ of a car-
cinogen are listed in Table 4 (Padgett, 1979) for a select group of carcin-
ogens targeted for study here. The yearly deaths in a given population that
is exposed to a carcinogen can be computed from the equation
computed deaths = fpe/1 ,
3
where p = population at risk, e = average exposure (|fg/m ); 1 = average
lifetime (= 70 years). Currently, risk factors are highly uncertain, and
Preceding page blank
-------
TABLE 3. TARGET CHEMICALS FOR SECOND-YEAR RESEARCH
Chemical Name*
Chloro- Fluorocarbons
Trichloromonof louromethane ( F 1 1 )
Oichlorodiflouromethane (F12)
Trichlorotrifluoroethane (F113)
Dichlorotetrafluoroethane (F114)
Halomethanes
Methyl chloride
Methyl bromide
Methyl iodide
Methylene chloride
Chloroform
Carbon tetrachloride
Haloethanes and halopropanes
Ethyl chloride
,1 Oichloroethane
.2 Oichloroethane
,2 Oibromoethane
.1,1 Trichloroethane
,1,2Trichloroethane
.1.1.2 Tetrachloroethane
,1.2,2 Tetrachloroethane
,2 Oiehloropropane
Chloroalkenes
Vinyledene chloride
(cis) 1,2 Oichloroethylene
Trichloroethylene
Tetrachloroethylene
Ally! chloride
Hexachloro-1.3 butadiene
Chloroaromatics
Monochlorobenzene
a-Chlorotoluene
o-Oichlorobenzene
m-Oichlorobenzene
P-Dichlorobenzene
1 ,2,4 Trichlorobenzene
Aromatic hydrocarbons
Benzene
Toluene
Ethyl benzene
m/p-Xylene
o-Xylene
4. Ethyl toluene
1,2.4 Trimethyl benzene
1 .3.5 Trimethyl benzene
Oxygenated and nitrogenated species
Formaldehyde
Phosgene
Peroxyacetyl nitrate (PAN)
Peroxypropionyl nitrate (PPN)
Acrylonitrilet
Chemical Formula
CCI3F
CCI2F2
CCI2FCCIF2
CCIF2CCIF2
CH3CI
CH3Br
CH3I
CH2a2
CHCI3
ca4
C2H5CI
CHCI2CH3
CH2aCH2CI
CH2BrCH2Br
CH3CCI3
CH2QCHCI2
CHCICCI3
CHCI2CHCI2
CH2OCHCICH3
CH2=CO2
CHCKHCI
CHCI=CCI2
CCI2=CCI2
C1CH2CH=CH2
CI2C=CCI-CCI»CCI2
C6H5CI
C6H5CH20
0-c6H4a2
m-C6H4CI2
p-CgH4Q2
1.2.4C6H3CI3
C6H6
C6H5CH3
C6H5C2H5
m/p-C6H4(CH3)2
o-C6H4(CH3)2
4-CeH4C2H5CH3
1.2.4C6H3|CH3)3
1.3,5C6H3(CH3)3
HCHO
COCI2
CH3COOON02
CH3CH2COOON02
CHSCN
Toxicityt
These chlorofluorocarbons
are nontoxic but have
excellent properties as tracers
of urban air masses
BM*
BM
SCt, BM
BM
SC.BM
SC. NBMt
-
NBM
SC.BM
SC
Weak BM
SC. NBM
NBM
SC.BM
BM
SC, ElM
NBM
SC.BM
SC
SC
BM-,
-
BM
-
-
—
-
SC
-
-
-
-
-
-
—
SC. BM
-
Phy to toxic
Phytotoxic
SC
'In addition to chemical species, meteorological parameters were measured. These were: wind speed, wind direction,
temperature, pressure, relative humidity and solar flux
tBM: Positive mutagenic activity based on Ames salmonella mutagenicity test (Bacterial Mutagens)
NBM: Not found to be mutagens in the Ames salmonella test (Not Bacterial Mutagens)
SC: Suspected Carcinogens
^Satisfactory measurement method for ambient analysis is not available
10
-------
TABLE 4. ESTIMATED UNIT RISK FACTORS FOR SELECTED
CARCINOGENS
Chemical
Chloroform
Carbon tetrachloride
1,2 Dichloroethane
1,2 Dibromoethane
Vinyl chloride
Vinyledene chloride
Trichloroethylene
Tetrachloroethylene
Ally! chloride
Benzene
Formaldehyde
Unit Risk
4.6 X
1.2 X
1.2 X
5.9 X
4.1 X
2.5 X
4.2 X
7.6 X
9.9 X
7.0 X
3.4 X
Factor, f *
io-6
io-6
10-5
1C'4
ID'6
io-5
ID'6
io-6
10'6
io-6
io-5
Source: Padgett (1979)
'Computed for a healthy male (70-kg weight) when exposed to an
average 1-Mg/m^ exposure over an extended period
insufficient exposure information is available to compute deaths caused by
carcinogens. However, those given here are useful for relative comparison.
FIELD INSTRUMENTATION
One of the primary motivations of our study was to conduct in-situ
analysis of trace chemicals, to minimize the many problems that arise when
samples are collected in vessels or in tubes filled with solid sorbents and
analyzed after long delays. It is widely agreed that the integrity of the air
samples is assured when careful in-situ analysis is performed.
All field work was therefore conducted in an in-situ mode using a suit-
ably instrumented mobile environmental laboratory. Table 5 summarizes the
equipment that was available on our mobile laboratory for the conduct of this
study. This laboratory was air conditioned for temperature control and
operated on a 220-V, 80-A circuit. Provision was also devised for operating
on 110-V input. A 200-m electrical cord was always used to station the
laboratory away from the electrical source or a power pole. The sampling man-
ifold was all stainless steel with a variable inlet height. In all cases the
sampling manifold was adjusted to be higher than nearby structures: A typical
manifold inlet height was 5 m above ground. For pumping and pressuring air
samples, a special stainless-steel metal bellows compression pump (Model MB
158) was always used.
11
-------
TABLE 5. ENVIRONMENTAL MOBILE LABORATORY INSTRUMENTATION*
Instrument
Features
Analysis
Perkin Elmer 3920 GC1
Perkin Elmer 3920 GC2
Perkin Elmer 3920 GC3
(capillary column GO
Coulometric dual EC-GC
Beckman 6800
Horiba AIA-24
Bendix 8101-B
Monitor Labs Model 8440E
Dasibi Model 1003 AH
AID Model 560
Bendix 8002
Eppley pyranometer
Eppley UV radiometer
Miscellaneous meteorological
equipment
Auto Lab IV Data System (No. 1)
SP-4000 Multichannel Data System
(No. 2)
Digitem Data System (No. 3)
Stainless-steel manifold
Teflon manifold
2ECDT,1dual FID*
2 ECD, 1 dual FID
2ECD. 1 dual FID
Coulometric ECD
FID
NDIR§
Chemiluminescent
Chemiluminescent
Photometric principle
Chemiluminescent
Chemiluminescent
Trace constituents
Trace constituents
Trace constituents
Halocarbons, PAN, PPN,
COC22; calibration
CO-CH4-THC
CO. C02
NO, N02
NO and N02
Ozone
Ozone
03
Solar flux
Ultraviolet radiative flux
Wind speed, wind direction,
temp, pressure, dew point,
relative humidity
GC data
GC data
All continuous air quality
and meteorological data
Sampling of HCs and
halocarbons
Sampling 03, NO, NOX
Note: Finnigan 3200 GC/MS available to this project at SRI
* Electron capture detector
tFlame ionization detector
§Nondispersive infrared
12
-------
EXPERIMENTAL PROCEDURES
Air Analysis
For all halogenated species and organic nitrogen compounds shown in Table
3, electron-capture detector (ECD) gas chromatography (GC) was the primary
means of analysis. The aromatic hydrocarbons were measured using flame-
ionization detector (FID) gas chromatography. Formaldehyde was the only spe-
cies measured by the wet chemical analysis technique utilizing the chromotro-
pic acid procedure (U.S. Public Health Science, 1965). Under normal operating
conditions 5 GC channels were operated with ECDs and only one with FID.
Although the exquisite sensitivity of the ECD would allow the determination of
several species in Table 3 with a direct 5-ml injection of air, preconcentra-
tion of air samples was necessary for efficient operation. All six GC chan-
nels were equipped with stainless-steel sampling valves and could be operated
either with a direct sampling loop or with a preconcentration trap. In no
instance was a sample size of greater than 1 liter used: In most cases, sample
volumes of 500 ml or less were satisfactory. Sample preconcentration was con-
ducted on a 4-inch-long bed of 100/120 mesh glass beads packed in a 1/16-inch
diameter stainless-steel tubing maintained at liquid oxygen temperature. The
glass beads could be replaced with an equivalent length of SE-30 packing (3
percent SE-30 on 100/120 mesh acid-washed chromosorb W) or glass wool with
completely satisfactory results. Desorption of chemicals from the preconcen-
tration traps was accomplished by holding the trap at boiling-water tempera-
ture and purging with carrier gas.
The sampling was achieved by pressurizing a 1-liter stainless-steel can-
ister to 32 psi. The sampling line and the pretrap (maintained at 90°C) were
flushed with ambient air and the canister pressure brought to 30 psi. Sam-
pling then began. The preconcentration trap was immersed in liquid oxygen and
an air volume sampled from pressure p} to P2« A high-precision pressure gauge
(±0.05 psi) was used to measure the canister pressure. A typical setting was
Pl = 30.0 psi and p£ a 24.0 psi. Ideal gas laws were found to hold excel-
lently at these pressures and were used to estimate sample volumes. The pres-
sure range of 30 to 20 psi assured smooth flow through the preconcentration
traps without problems of plugging. All other sampling was accomplished by
using sampling loops that were flushed with all-glass syringes of 100-ml
volume.
Table 6 summarizes methods used for the analysis of trace species. The
GC condition used are also stated. Because of the dominant water response of
the ECD, a post-column Ascarite trap was inserted to remove water from halo-
carbon analysis. No water trap was used for the analysis of aromatic hydro-
carbons, PAN, PPN, and phosgene.
The identity of trace constituents was established by using the following
criteria:
9 Retention times on multiple GC columns (minimum of two columns)
• EC thermal response
13
-------
TABLE 6. ANALYTICAL CONDITIONS FOR THE ANALYSIS OF SELECTED TOXIC CHEMICALS
GC Column
No.
1
2
3
4
5
6
7
8
Description
6 ft X 1/8 in. SS." 20% SP2100.
0. 1 % CW 1 500 on 100/1 20 mesh
Supelcoport
33 ft X 1/8 in. Ni. 20% DC 200
on 80/100 mesh Supelcoport
6 ft X 1/8 in. SS. 10% N. N. -bis
(2-cyanoethyl) Formamide on
Chromosorb P (A/W)
3ftX 1/8 in. Ni, 5%SP1200
-5% Bentone on 100/120
mesh Supelcoport
15 ft X 1/8 in. SS, 10% SP 1000
on 100/1 20 mesh Supelcoport
10 ft X 1/8 in. SS. 0.2% CW 1500
80/100 mesh on carbopack C
10 in X 1/4 in. Teflon. 5% CW
400. on 60/80 mesh Chromosorb
W(A/W)
5 ft X 1/4 in. SS. 30% didecyl
phthalate. 100/120 mesh.
Chromosorb P (A/W)
Temp.
<°C)
45
45
65
65
45
45
30
30
Species Measured
CHCI3; CH3CCI3; CCI4; cis-CHCICHCI .
C2HCI3;CH2CICHCI2;C2CI4;
CH3CHCI2; CH2CICCI3; CHCI2CHCI2;
CH2CICHCICH3
CH3CI; CH3Br; CH2CCI2; CH3I;
CCI3F;CCI2F2;CCIF2CCI2F;
CCIF2CCIF2
C6H6; C6H5CH3; m/p/o-C6H4(CH3)2;
4-C6H4C2H5; 1.3.5 C6H3(CH3)3;
1.2,4C6H3(CH3)3
C6H5CI; m-C6H4CI2; o C6H4d2;
1.2.4 C6H3CI3; C6H5CH2CI;
CCI2CCICCICCI2
CH2CICH2a
CH2CI2; CCI3F; cis CHCICHCI; CH3I;
CCI2FCCIF2; CH3CCI3; CCI4;
C2H5a;CH2CHCH2CI
PAN, PPN
COCIo
Detector
Type
Electron
capture
Electron
capture
Flame
ionization
Electron
capture
Electron
capture
Electron
capture
Electron
capture
Electron
capture
Temp.
<°C)
275
275
275
275
265
265
30
30
Typical
Carrier Gas
Flow Rate
(ml/min)
40
25
45
45
25
40
60
70
Typical
Sample
Size
(ml)
500
500
500
750
100
10
5
5
Remarks
No water trap
Ascarite water trap
No water trap
No water trap
Ascarite water trap
Ascarite water trap;
also used for CH2CCI2
measurement with
preconcentration
No water trap
No water trap
'Stainless steel
-------
• EC ionization efficiency
• Limited GC/MS analysis.
Details of these comparisons for halocarbon species, organic nitrogen com-
pounds, and aromatic hydrocarbons have already been published and need not be
repeated here (Singh et al., 1979).
CALIBRATIONS
Calibrations for all species were performed using three basic methods:
• Permeation tubes
• Multiple dilutions
• Gas-phase coulometry.
As reported earlier (Singh et al., 1979), permeation tubes provide the best
means to generate low-ppb primary standards for a significant number of chemi-
cals listed in Table 3. However, these were unacceptable for a large number
of species. Based on our previous experience, we concluded that unacceptable
permeation tubes could operate satisfactorily at high temperatures. There-
fore, two temperature baths maintained at 30.0 ±0.05°C and 70.0 ±0.1°C were
installed. The 30°C bath was a water bath, and the 70°C bath was an oil bath.
All permeation tubes were contained in specialized holders and were purged
continuously with a prepurified gas (He, air, or N£) flowing at 50 to 80
ml/min. A large-volume mixing chamber was installed at the permeation tube
exit to allow for complete mixing. Syringe samples were withdrawn from the
mixing chamber using all-glass syringes. With the installation of the 70°C '•"
bath, all permeation tubes performed excellently. Table 7 reports the mea-
sured permeation-rate data for each of the chemical constituents of interest.
It is clear from Table 7 that many species (e.g. CC14, CH3CC13, C^BrC^Br,
chloroaromatics) for which permeation tubes could not be used earlier are now
giving excellent results. Figure 1 demonstrates the excellent linearity of
the permeation rate for some of these chemicals. Overall, we believe that
this offers the best, most-accurate means of generating primary standards.
It is also clear from Table 7 that most of these permeation tubes can be
used to prepare standards directly at parts per billion (ppb) concentration
levels. Batch dilutions were carried out to reduce these concentrations by a
factor of 1Q2 to 103. Over a wide range of concentration levels of several
ppb's and low ppt's, the frequency-modulated ECDs that we used were completely
linear. The linearity of the FID over a much larger concentration range is
well known.
In addition to permeation tubes, standards were obtained from Scott-
Marrin (Riverside, California). These were obtained at higher concentrations
(5 to 10 ppm) for reasons of long-term stability. Table 8 lists the chemi-
cals, the standard concentrations, and the cylinder materials. All of the
chemicals were stored in aluminum cylinders except those containing CH^Cl,
which were contained in stainless-steel cylinders. Extreme care was required
15
-------
TABLE 7. PERMEATION RATE DATA FOR GENERATING PRIMARY STANDARDS
Compound
CH^CHCHO
CH2OCH2
Ca2F2(F12)
CCI3F(F11)
CHd2F IF21)
CHOF2 (F22)
Ca2FCCIF2(F113)
CCIF2CCIF2(F114)
CH3CI
c2H5a
CH2CHd
dCH2CH-CH2
CH3Br
CH3I
CH2CI2
(cis) CHCICHCI
(trans) CHCICHO
CQ2CH2
CH2CICH2CI
CH2dCH2O
CHd2CH3
CH2OCHdCH3
(trans) CHCI-CHCH2CI
COCI2
CHCI3
C2HO3
CCI3CH3
Cd3CH3
CHCI2CH2CI
CCI4
C2d4
C2CI4
CH2BrCH2Br
CHBr3
C6H5CI
C6H5CH2CI
o-C6H4CI2
m-C6H4CI2
P-C6H4CI2
Permeation
Tube Number
or I.D.
2356
1908
6138
1911
2347
2348
1238
2345
2355
2350
2352
7497
1893
1239
2354
1939
1898
1897
1907
1899
2353
MET1
MET2
2351
1229
1235
1896
1589
1901
1894
1902
1590
1237
1895
MET3
MET4
MET5
MET6
MET7
Temperature.
<°c-i
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
70.0
30.0
30.0
70.0
70.0
30.0
30.0
30.0
70.0
70.0
30.0
70.0
70.0
30.0
70.0
70.0
70.0
70.0
70.0
70.0
70.0
Permeation Rate
ng/min
969
1120
615
1680
942
80
715
6254
1915
480
1270
142
2477
109
523
2564
1696
731
2622
125
71
2456
7806
942
174
314
980
3450
129
1983
3352
706
1220
1316
4507
1528
1359
2515
1596
ppb/l/min
(25°C. 1 atm)
423
618
123
299
224
23
93
894
927
182
497
45
638
19
150
646
428
184
648
31
18
531
1720
233
36
58
179
632
24
315
494
104
160
127
980
295
226
418
265
Status*
S
S
S
S
S
?
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
Quality*
E
t
E
E
E
E
E
E
E
E
E
E
G
G
E
G
G
G
E
G
G
E
E
E
G
E
E
E
G
E
E
E
E
E
E
E
E
E
E
NOTE: All permeation tubes were given a 2 week or longer conditioning time
'Temperature maintained to ± 0.05°C
'E-Excellent (errors in permeation rate < ±10%); G-Good (errors in permeation rate < ±15%): S-Satisfactory (115 %)
16
-------
5°
0.20
0.18
0.16
i
0.14
9
0.12
O
UJ
S 0.10
HI
0)
t-
O
0.08
uj 0.06
5
0.04
0.02
0.00
2BrCH2Br (wo = 6.8)
vv*-
0-CBH4CI2>\\>
(w. - 13.7) V^S "^
CCI4
-------
TABLE 8. PPM LEVEL PRIMARY STANDARDS IN AIR*
Standard and Compound^
ST
1,1.1 Trichloroethane
Carbon tetrachloride
1,2 Dibromoethane
Hexachloroethane
S2
Monochlorobenzene
o-dichlorobenzene
S3 '
Benzene
Toluene
S4
Methyl chloride
Methylene chloride
1,2 Dichloroethane
S5
Trichloroethylene
Tetrachloroethylene
Chloroform
Concentration (ppm)
5.0
5.2
5.0
0.8
5.0
5.0
5.0
5.0
10.0
10.0
10.0
10.0
10.0
10.0
Long-term
Stability}:
(1-year period)
E
P
E
U
P
P
E
E
E
E
E
E
E
E
Cylinder
Type
Aluminum
Aluminum
Aluminum
Stainless steel
Aluminum
Size (ft3)
30
150
150
30
30
'Obtained on order from Scott-Marrin, Inc., Riverside, California
tFor all of these chemicals (except CgHg and Cgh^CK) satisfactory permeation tubes were also operational.
Therefore, a majority of these standards were used more as secondary standards than as primary ones. For
aromatic hydrocarbons, the Scott-Marrin standards were used as primary standards
tE: excellent; P: poor; U: unknown
Secondary Standards
Except for the aromatic hydrocarbons, it was not possible to use primary
standards during field operation. Therefore, an optimal scheme that depended
on the use of secondary standards was devised.
A 35 liter and several 5-liter (as back-ups) polished stainless-steel
samplers were filled with urban air samples to a pressure of 35 to 40 psi.
18
-------
These were allowed to stabilize for one to two days and then analyzed by com-
paring them against the primary standards. The 35-liter pressurized secondary
standard was then used for field operation: Each GC channel was calibrated
about 3 times a day with this secondary standard. The stability of nearly all
species over a period of several days was found to be excellent. Some spe-
cies, such as PAN, PPN, or COC12, could not be stored for any reasonable
length of time. This was not a serious hinderance since other chemicals could
be used to ascertain the constancy of the BCD and the FID responses during
field operations. All of the Scott-Marrin standards were also carried on
board after these had been diluted to low ppb levels. These were also used as
secondary standards (in addition to the collected air samples). The stability
of the diluted Scott-Marrin cylinders (in polished 1- to 5-liter stainless
steel vessels) was found to be excellent. Analysis of these prior to field
experimentation, during field studies, and after the completion of field stud-
ies did not show a charge from the measurement precision under field
conditions.
QUALITY CONTROL
Two major factors were critical in establishing the quality of the
acquired date: the accuracy of primary standards and precision and repeatabil-
ity of measurements. As stated earlier in this section, the primary standards
commercially obtained were compared with our permeation tubes which can be
routinely used to obtain reliable standards within errors of ±5 to 10 percent.
The aromatic hydrocarbon standards were compared with NBS propane standards
and found to be accurate to within ±5 percent. The cross-calibrations between
SRI generated standards and Scott-Marrin standards typically results in dif-
ferences of about ±10 percent or less. The use of secondary standards nearly
three times a day clearly demonstrated the excellent precision that was
obtainable during field studies. The precision of reported field measurements
is estimated to be ±5 percent. The measurements presented here have an
overall estimated accuracy of better than ±15 percent.
19
-------
SECTION 5
PLAN OF FIELD MEASUREMENTS
The. first quarter of this project was devoted to developing methods for
accurately analyzing a comprehensive list of toxic chemicals and to procuring
supplies and equipment for the four planned field studies.
After the measurement methodology was developed, field studies were con-
ducted in selected urban sites. The four sites selected were in Houston,
Texas; St. Louis, Missouri; Denver, Colorado; and Riverside, California. In
all cases, the sites represented an open urban atmosphere. There were no
nearby sources or topographical features that could directly affect the repre-
sentativeness of the measurements. Figure 2 shows the location of these
sites. Each field study was of about two-weeks duration. Despite the logis-
tical difficulty, a 24-hour measurement schedule offers the most efficient
means of collecting the maximum amount of data to characterize the burden of
toxic organic chemicals in the ambient air. In addition, night abundances of
trace chemicals are likely to provide crucial information about the sources
and sinks of measured species. Therefore, during all field programs a 24-
hour-per-day, seven-days-a-week measurement schedule was followed.
Although meteorological analysis has not yet been completed, general
weather conditions were not unusually severe. In Houston, rainfall and pas-
sage of fronts did not allow for severe pollution episodes. St. Louis weather
produced relatively clean environmental conditions. Weather in Denver was
moderately hot and stagnant. At Riverside, the first half of the study period
exhibited relatively clean conditions; the second half was more representative
of hot and somewhat stagnant conditions.
Preceding page blank
21
-------
.-.^---i-S1 DALLAS i ';
'•' s.iV*«. •-, > I
FORT; r>, \ - J.- t
''WORTH • \ X. T
1 / *> v \ i
WACO
(a) HOUSTON. TX, SITE (29° 47' N. 96° 16' W) (bl ST LOUIS, MO, SITE (38° 46' N. 90° 17' W)
\ t
\ BOULDER ; ] ; /'
/ V*v *1 | I /
D^-;"V\
> , '.
COLORADO SPRINGST/*
i \
.! N -\
'•*-» \'« :-•--.
'. - VIM«:-- • - - PASADENA
PALMDALE
LOS ANGELES
'Vv
>iN \X RIVERSIDE
A**"V """""-,'-. ..''ji's'TE 1
(c) DENVER, CO, SITE (39° 45' N. 104° 59' W) (d) RIVERSIDE, CA, SITE (33° 59' N, 117° 18' W)
Figure 2. Location of field sites during the second year.
22
-------
SECTION 6
ANALYSIS OF FIELD DATA
Experiments at all sites were performed satisfactorily, and no breakdowns
were encountered. The field operations were conducted around-the-clock on a
seven-day-per-week basis. This allowed the collection of a large body of
data. The entire data base was collected, validated, and compiled on our mas-
ter data file. This file also contains the data that were collected in the
first year of this research effort. All of the meteorological information is
currently on chart papers and is easily accessible. The toxic-chemical master
data file will be updated as additional studies are conducted. We have com-
piled, validated, and statistically treated the collected data, but no
detailed meteorological analyses of these data have been conducted. The
interpretation of data is therefore by no means complete, and further analysis
and interpretations will continue.
ATMOSPHERIC ABUNDANCES, DAILY EXPOSURES*, FATES,
AND VARIABILITIES OF MEASURED SPECIES
Table 9 summarizes data on all of the organic chemicals measured during
the four field studies; maximum, minimum, and average concentrations are
presented for each of the measured species. The averages and the standard
deviations associated with the concentration data are calculated from the
actual data acquired and involve no interpolations. In addition, Table 9
presents an average daily outdoor dose for each of the species and the stan-
dard deviations associated with this average daily dose. The dose is deter-
mined based on an average daily air intake of 23 m at 25°C and 1 atmosphere
for a 70-kg male. The daily doses were calculated by estimating hourly values
by linear interpolations between measured data. The reported-dose data in
Table 9 represent the average of daily average doses and the standard devia-
tions associated with variabilities in the daily means.
Much of the information presented in Table 9 is self-explanatory, so only
salient observations will be made below. Table 10 (presented earlier as Table
2) summarizes the total average exposure for the four sites to each chemical
category as defined in Table 9.
The terms "daily exposure" and daily dosage" are used interchangeably and do
not include the efficiency of chemical absorption in the human body.
23
-------
TADIE 0 CONCENTRATIONS AND OAILV OUIDOOH EXPOSURES OF MEASURED CHEMICAL SPECIES
Ch*fnic*l Gioup and Spvcm
liichlototluotonMinm IF 1 11
DicMu*ot1uo>o>n«ih#i« IF 121
TikMotonua>Mfh«iw IF 1 13t
Mtthyl cMutHte
Methyl iodide
Mtthyten* chlotMj*
C*> bun If tricht CMMta
Crtiyl chluiid*
1.1 D>cMa.o>lh.nt
1.2 D>b.wnoclt>«n*
1.1,1 liietiloiMitMn*
1.1.2 tnchhMMth«w
1.1.1.7 1*1>*CtirufOtttl*n«
1.1.2.2 T*ii»thlu(o*thM>«
VinytetltfM thluKd*
O Otchla'bbcn/tn*
m DicMcx otttn/m
P Dtchlwotent tn«
ToluC««
Ethyl banicn*
nt'p Xyltnt
D Xytonc
4 f ihyl lotiwnc
1.3.5 t'mxlhyl b«n^>fM
P«.o.»*.«l¥l.,.|i«tr (FAN)
Houiian - S>u 4
114- 76 Ifay 19801
Concwiti«iioo
fppit
Mun
474
897
78
955
too
36
574
404
63
1517
59
353
37
17
It
61
25
71
144
11
300
7
7
2
6 780
IO330
1380
3640
1307
6/0
I15O
460
<20
438
SO.'
178
474
190
10
4O3
56
2.2
653
449
70
1863
/2
263
74
IS
37
36
59
105
598
70
517
9
6
7
5680
10850
I4OO
4270
1460
1030
1470
BOO
B35
MM
ttos
7817
1664
58
7184
778
3404
7934
176
7300
368
1499
179
80
753
980
3715
154
7785
58
67
47
13
37700
65650
7780
73780
9790
7470
9760
5350
4150
M-n.
305
487
37
17
531
45
Ob
49
126
9
50
to
134
7
72
34
1
0
1
t
840
IO40
50
270
80
60
50
;o
«- 10
°i"tothuT'"
**•'•«•
596
1035
37.7
45
466
03
04
430
61.6
6 1
1250
90
41 5
1 1
85
614
2.7
344
10
0 7
04
4497
8224
1367
362 1
173 t
903
tine
77 1
440
SO
115
307
765
09
163
33
0?
246
433
1 1
81.1
56
128
14
61.9
7 7
248
0 7
03
0 1
7833
4199
948
7194
658
440
547
715
454
Si lou'i - S.I. 5
179 M*v-0 Jun 1980)
CanccntfMion
IPfHl
M.*.
374
627
137
75
B1
76
421
179
60
124
16
735
63
39
376
3
740
6
4
1
1410
1570
640
950
310
740
370
530
11300
<70
771
SD
105
1B7
171
6
138
75
1 B
583
6
14
101
4
136
12
8
154
955
7
243
It
8
1
1190
1750
460
703
300
tea
3/0
490
4500
703
MM
90S
1156
1791
37
1015
ITS
6407
MB
106
607
76
896
45
88
66
1040
76O4
10
1167
95
55
4
5820
6450
7100
3230
1490
1240
2560
1360
IB/OO
890
M",
217
383
22
13
531
7
8?
75
117
76
45
8
137
6
77
75
8
67
5
t
110
103
50
110
60
80
60
80
8100
40
(pa/a
*"'•«•
466
68 7
71 9
40
34 1
7 7
793
195
66
11 4
78
780
1.9
35
13 S
584
0 t
236
910
1260
449
868
719
197
174
787
3190
744
WMM«
*vl
SO
7.1
126
S 1
OS
12
1 7
105
1 8
09
1 1
09
4 t
O4
7 1
04
02
05
74
729
0?
103
484
U49
739
509
110
II 3
760
136
I77O
80
115-28 JunlB80)
**""
637
1005
721
34
763
124
967
IBS
174
41
65
241
31
713
27
76
IBB
394
2
790
4390
6240
2220
2860
1280
900
1410
340
I23OO
443
Conunuciion
tpplt
SO.
255
565
235
9
132
SI
926
206
19
24
31
797
16
553
10
81
313
156
t
717
3940
5280
313O
337O
17IO
760
2310
740
5900
1746
MM.
1246
3178
16O8
60
1157
227
4874
1630
274
ITS
14?
7089
78
7699
50
90
805
7483
113O
1
1114
38
35
239)0
74000
18520
70850
0000
4380
15450
1790
78700
<70
1164?
MM.
789
471
28
619
23
108
19
116
10
11
64
10
171
7
20
7
99
04
33
1
110
290
90
150
OO
70
130
30
6600
12
Dairy C
IP*/
*~"*
82.2
107.9
«SO
366
112
76 1
180
252
2.4
6.3
203
92.3
S.?
73
734
596
06
776
10
307.4
stie
1955
2633
n?r
68 1
1720
703
3470
< 1
460
wT"
SO
182
245
71.3
48
34
34.6
92
1 4
06
1.0
60
09
31.7
00
1.2
24
31 2
11.4
02
124
06
129B
1731
948
1308
600
316
113
1670
214
RiMraidk - Siu 7
ii- is July lean
ConcMtUttion
(MM)
M**n
671
IOS6
274
7O3
269
1949
703
175
87
06
357
22
747
41
ft)
80
118
484
4
10
3950
6800
1330
7731
1100
82O
740
73O
• SO
1BOOO
• SO
1196
193
SD.
318
4OI
702
179
107
1400
798
23
85
22
32S
7
257
21
IS
14
65
738
3
7
1910
3070
67O
ISIS
6SO
460
SOO
170
7600
1249
197
MM.
I860
2804
2211
1663
1033
9470
474*
707
at?
147
7SOS
47
1349
89
18
80
60
173
230
1020
16
40
10960
20070
4000
7340
3140
7650
3170
1760
41000
5760
900
Mm.
201
667
26
437
43
478
109
1SI
16
a
03
10
70S
4
11
<4
33
IS
173
1
1
2
670
450
2SO
360
80
70
100
70
10400
170
"wET
*"•"*
878
ITS?
448
348
736
1691
76 1
7S2
61
6 1
318
39
978
SO
I.I
1,4
60
06
54
145
re 7
i.i
08
1 7
7804
4969
127.7
2155
1077
858
784
136
6300
-75
1388
197
SO.
199
350
II S
83
123
0?
S3. 7
44.3
10
IB
1.1
123
OS
178
2.1
03
03
10
03
OS
3?
208
03
O4
03
03
03.9
ISSB
309
529
229
226
607
56
2I5O
83
-------
TABLE 10. SUMMARY OF EXPOSURE TO HAZARDOUS
ORGANIC CHEMICAL GROUPS
Chemical Category*
Chlorofluorocarbonst
Halomethanes
Haloethanes and
halopropanes
Chloroalkenes
Chloroaromatics
Aromatic hydrocarbons
Oxygenated species
Total Average Daily Exposure (jig/day)
Houston -
Site 4
205
203
210
88
37
2130
-
St. Louis -
SiteS
141
97
59
78
25
430
344
Denver —
SiteS
241
168
137
92
34
1616
396
Riverside -
Site 7
262
319
153
98
-
1401
696
Average
of Sites
212
197
140
89
32
1394
479
*As defined in Table 9
tNOT suspected to be directly toxic
DATA ANALYSIS BY CHEMICAL CATEGORY
Chlorofluorocarbons (CFCs)
Four CFCs (fluorocarbon 11, 12, 113 and 114) were measured. As indicated
earlier (Table 3), CFCs are not expected to be toxic to the human body. They
do, however, act as useful indicators of urban transport, and the involvement
of these halocarbons in stratospheric ozone destruction is well known. It is
clear from Table 9 that the mean F12:F11 ratio at Site 4 is 1.9, while this
ratio is between 1.6 and 1.7 for the other sites. While emissions information
for F12 and Fll for 1980 is not available, an F12:F11 ratio of 1.6 to 1.7 is
consistent with cumulative emission rates. The Houston ratio is slightly
higher but probably reflects a greater use of air-conditioned automobiles that
use F12 as a refrigerant. The consistency in data is much less obvious when
one considers the F12:F113 ratios: this ratio varied between 3 and 5 at all of
the sites. Past emission ratios would suggest that this ratio should be
greater than 10. To the extent that urban data can act as an early warning
indicator of major changes in use patterns, it would seem that emissions of
F113 are increasing at a faster rate than all other fluorocarbons. Since F113
is comparable to Fll in its stratospheric-ozone-destroying efficiency, its use
should be watched more carefully. The F114 levels are reasonable and not
inconsistent with available emissions data.
25
-------
Halomethanes
Six halomethanes were measured. As can be seen from Table 3, all six of
these chemicals are either mutagens or suspected carcinogens. It should be
pointed out that methyl chloride, one of the most dominant natural chlorine
carriers, is also found to be mutagenic in the salmonella mutagenicity tests.
Methyl bromide and methylene chloride are also mutagens (Table 3). The total
intake of halomethanes varies between 100 and 300 jag/day, depending upon the
city and the prevailing weather conditions (Table 10).
Average methyl chloride levels were typically less than 1 ppb. Measured
levels of approximately 700 parts per trillion (ppt) at Sites 5, 6, and 7 are
only slightly elevated above the expected background (= 600 parts per tril-
lion). However, the variability in methyl chloride levels at Site 4 (Houston)
was significant. Figure 3(a), (b), and (c) best demonstrates the selective
sources of methyl chloride. While general meteorological conditions at St.
Louis did not allow for much pollution, this was not the case at Riverside.
Days 6 through 10 at Riverside were extremely polluted (as shall be seen
later) and yet little variability in methyl chloride was found. From Figure
3, one can conclude that methyl chloride may be found significantly above
background levels only in some urban centers.
The behavior of methyl bromide was more typical of an urban pollutant.
It is safe to assume that in most polluted environments methyl bromide levels
are significantly above the expected background of about 10 to 15 parts per
trillion. The unusually high levels measured in Riverside (average of 0.26
ppb) are consistent with similarly high values reported previously for the
nearby city of Los Angeles (Singh et al., 1979). Figure 4 clearly shows the
variability in methyl bromide levels that is consistent with other anthropo-
genic pollutants (e.g. methylene chloride).
Methyl iodide was carefully measured to avoid any possible interferences
from other pollutants. It was resolved on two different GC columns: The
results were essentially identical. Average methyl iodide levels were between
2 and 4 parts per trillion at all sites. At no time did the concentration
exceed 11 parts per trillion. Methyl iodide is a suspected carcinogen (Table
3), and yet it is a component of the natural atmosphere. Typical levels of 4
to 6 parts per trillion are encountered in the marine environments. It
appears that methyl iodide has no sources in the urban environment. Figure 5
shows a mild diurnal variation in methyl iodide with a slight dip in the
afternoon levels.
Methylene chloride is clearly a large volume organic chemical (concentra-
tions reached as high as 9 ppb). At all sites the average concentration
exceeded 0.4 ppb, and the concentration was highest in Riverside (average =
1.9 ppb). This is somewhat lower than the average concentration of 3.8 ppb
measured in central Los Angeles (Singh et al., 1979). The diurnal behavior of
methylene chloride at Houston and Denver [Figure 6(a) and (b)] was somewhat
similar and showed reduced levels in the afternoon. This is contrary to the
behavior observed at Riverside where a distinct afternoon maximum is observed
[Figure 6(c)]. This is in part attributable to the downwind location of
Riverside, which is subject to transport from Los Angeles. Figure 7 clearly
26
-------
§ 2500
1 2000
1500
500
0
012345678
TIME — days
(a) HOUSTON. TX — 15-24 MAY 1980
10
JIAJU
1 2500
«
B 2000
3
L 1500
3 1000
r>
500
0
i • i • i • i • i * i • i • i ' i '
_
"••-*• ' - . '
'** > ' 0 fO . 0 „
__ ° ° 0 T>° O 0 ° „
i . i . i . i . I . i . i , t . t
0123456789 10
TIME — days
(b) ST. LOUIS. MO — 30 MAY-8 JUNE 1980
c
g
\
I
\
u
0
3000
2500
2000
1500
1000
500
0
i • i • i • i i
-
a
_ 0
' ° ° ° * ° 0 » „ 0 - = 00 0» 0°0 •
~ a ° ~
i . 1 . I . I . I
0123456789 10
TIME — days
(c) RIVERSIDE, CA — 2-12 JULY 1980
Figure 3. Atmospheric concentration of methyl chloride.
27
-------
1400
- 1000
I
g 800
&
I 600
a 400
l"
0 200
01 23456789 10
TIME — dayi
(•) ST. LOUIS. MO — 30-MAY-8 JUNE 1980
1400
- 1000
I
S 800
?" 600
o 400
I
0 200
0 2 4 6 8 10
TIME — days
(b) RIVERSIDE. CA — 2-12 JULY 1980
Figure 4. Atmospheric concentration of methyl bromide.
28
-------
| 16
i
5 12
&
l" 8
o
0
C
1 ' I ' i ' 1
-
"} 1 I I 1 II I i 1 ' ! •
i . i . i . i .
) 5 10 15 20 2E
TIME — hour
20
lie
t
&
512
s
1
u
0
e
(a) HOUSTON, TX — 15-24 MAY 1980
i • i • i ' i
-
"i n ' 1 1 j n J n :
i . i . i . i
5 10 15 20 25
TIME — hour
(b) RIVERSIDE, CA — 2-12 JULY 1980
Figure 5. Mean diurnal variation of methyl iodide.
29
-------
tuuu
3500
c
.2
= 3000
1 2500
5
| 2000
1 1500
(V
°N 1000
I
o
500
n
.
-
-
-
.
-
-'
i ' i ' i ' i
•
-
_
•
-
'
-r J
I
-
.
_
, ... , -
5 10 15 20
TIME — hour
(a) HOUSTON, TX — 15-24 MAY 1980
25
4000
c 3500
o
| 3000
1 2500
J 2000
1 1500
M
°N 1000
5 500
0
1 • 1 • 1 • I
]
_
.
_'
_
-
•
1
T ™
i
i
1
5 I i
-
1
—
-
5 10 15 20-
TIME — hour
(b) DENVER, CO — 16-26 JUNE 1980
25
4000
3500
i 3000
i 2500
[ 2000
1500
N
$ 1000
N
3 500
f\
i " 1
—
-
-
!I I I
I T T
* 1
-
t . 1
0 5 10
1
1
t
(
,
i
_
-
-
-
I -
X -L
_
L
I.I.
15 20 2
TIME — hour
(c) RIVERSIDE, CA — 2-12 JULY 1980
Figure 6. Mean diurnal variation of methytene chloride.
30
-------
| 8000
'C
*• 6000
t
| 4000
M
5* 2000
0
(
I ' 1 ' 1 1 1
• ° •
-
• ' ' :
•. -
» a 0° o ° o o .
a o A/*° *J ° rf
i . i . I . i . i
) 2 4 6 8 10
TIME — days
Figure 7. Atmospheric concentration of methylene chloride
at Riverside, CA, 2-12 July 1980.
shows the observation made earlier that the last half of our stay at Riverside
showed significantly greater pollution than the first half. The average
intake of methylene chloride varied from 30 to 160 ug/day at all sites.
Chloroform levels are significantly elevated in the urban environments.
Concentrations approaching 5 ppb were encountered at more than one site. The
average daily intake of chloroform was as low as 9 ng/day in St. Louis and was
close to 80 ug/day in Riverside (Table 9). The sources of cloroform are still
largely unknown but automobiles, chlorination of water, and direct emissions
probably all contribute significantly. The variability of chloroform at
Riverside is nearly identical to methylene chloride (Figures 7 and 8), further
confirming its urban source.
Unlike most other man-made pollutants, carbon tetrachloride showed little
variability at all sites except at Houston. This is clearly shown in Figure
9. The lack of variability of carbon tetrachloride at Riverside is intrigu-
ing. Carbon tetrachloride levels as high as 3 ppb were encountered (Table 9).
The average daily intake at all sites was typically between 18 and 25 fig/day
except in Houston, where it was 62 fig/day.
Haloethanes and Halopropanes
Nine important chemicals in this category were measured (Table 9). This
is the first measurement of ethyl chloride, and no comparative data are avail-
able. It is estimated that 0.01 million tons of ethyl chloride is released
into the atmosphere every year in the United States. Our measurements sug-
gested high levels of this chemical in Houston, where concentrations as high
as 1.3 ppb were encountered. The average concentration (0.23 ppb) and the
daily average dose (14 ^ig/day) were also highest in Houston (Figure 10).
31
-------
5000
1 4000
8. 3000
2
a
I 2000
5 1000
„%
a
0 o _.
4 6
TIME — dayi
10
Figure 8. Atmospheric concentration of chloroform
at Riverside, CA, 2-12 July 1980.
1
£
i
|
1
*
8
3000
2500
2000
1500
1000
500
0
l • l ' I :' i • i • i ' i • i ' i
-
-
a
u
s e
.
„= = „
c ,
s . r.- " r. 1: . _
c:: " - .
- C -Z .. - .i:" • ,.
agio. & z " sS^T.^'^.-s. = •!."-«--3hc.1." " w-'-
1 . ! . 1 . 1 1 ' . 1 1 . : 1 .
01234 56789 10
TIME — days
(a) HOUSTON, TX — 15-24 MAY 1980
3000
c 2500
o
S 2000
i
t 1500
I 1000
° 500
0
1 ' 1 • 1 ' 1 • . 1
J
j
1
i
T~ * "". "~i ' '. ' • . "i . T ' i
8
10
0246
TIME — days
(b) RIVERSIDE, CA — 2-12 JULY 1980
Figure 9. Atmospheric concentration of carbon tetrachloride.
32
-------
1400
1 120°
I 1000
&
r 800
I 600
°«400
z
N
0 200
12345671
TIME — days
(•) HOUSTON. TX — 15-24 MAY 1980
9 10
1400
I 1200
| 1000
f 800
O.
I 600
x" 400
° 200
0
O 3
8
10
246
TIME — days
(b) RIVERSIDE, CA — 2-12 JULY 1980
Figure 10. Atmospheric concentration of ethyl chloride.
Average levels in St. Louis, Denver, and Riverside were 0.05 ppb, 0.04 ppb,
and 0.09 ppb respectively (Table 9). Typical measured levels are not incon-
sistent with estimated emissions. No toxicity data on ethyl chloride was
available.
Unlike ethyl chloride, the variability in 1,1 dichloroethane was not
large. Average concentrations were between 0.06 ppb and 0.07 ppb at all
sites, and concentrations did not exceed 0.15 ppb. A daily average dose of 6
pg/day is calculated for all four sites. Based on the meteorological condi-
tion a diurnal trend was evident. Figure 11 shows this behavior at Denver
(Site 6) and Riverside (Site 7). 1,1 Dichloroethane is not found to be a bac-
terial mutagen (Table 3).
1,2 Dichloroethane is a large-volume chemical that is also a suspected
mutagen and a carcinogen (Table 3). Its estimated yearly U.S. emissions
exceed 0.2 million tons. The distribution of 1,2 dichloroethane was widely
different at the four sites but was highest in Houston, where concentrations
as high as 7.3 ppb were measured (Figure 12). The average 1,2 dichloroethane
33
-------
zuu
1
1 150
L.
Q)
a
2
ft 100
1
M
0
5 so
n
u
0
1
-
-,
•
!
1
i
i
1
:i ,
I]
i
i
-
•
• -
i ' '
•i-
i
05 10 15 20
TIME — hour
(a) DENVER, CO — 16-26 JUNE 1980
25
200
c
o
1 150
i
M
Q. 100
I
N
O
5 50
n
X
u
0
1 • t 1
-
.
..ll'lil,
I.I.I
1
-
-
1111.
1
20
0 5 10 15
TIME — hour
(b) RIVERSIDE. CA — 2-12 JULY 1980
25
Figure 11. Mean diurnal variation of 1,1 dichloroethane.
| 8000
I
t 6000
^,000
U
O 2000
N
5
0
' i i • i • i
=1
01234 587 89 10
TIME — days
Figure 12. Atmospheric concentration of 1,2 dichloroethane.
34
-------
concentration in Houston was 1.5 ppb, which was an order of magnitude higher
than the lowest average measure'd at St. Louis (Table 9). While the.diurnal
variation at Houston does not follow any special trend, the diurnal trend at
Denver is very much like that of 1,1 dichloroethane (Figure 13).
The high 1,2 dichloroethane concentrations in Houston were measured
although the weather on several days was rainy and windy and unsuited for pol-
lutant accumulation. During more typical (stagnant) summer weather, this site
has the potential to be a toxic "hotspot." The lack of a reasonable diurnal
variation of 1,2 dichloroethane at Houston is probably attributable to con-
stantly changing weather conditions and the proximity of local sources. The
lowest measured level of about 45 parts per trillion is representative of the
background of 1,2 dichloroethane in the free troposphere at midlatitudes.
1,2 Dibromoethane is a suspected carcinogen (Table 3) that has a high
risk associated with its exposure (Table 4). Fortunately, the levels of 1,2
dibromoethane are moderately low at all sites and the average concentration
did not exceed 0.06 ppb at any of the four sites. The highest concentration
of 0.37 ppb was measured at Houston. This may be partially attributed to the
4000
c
.2 3500
* 3000
i.
g 2500
g
• 2000
O 1500
N
X
g 1000
-------
proximity of this site to Highway 10. The average daily exposure at all sites
varied between 3 and 10 ^g/day. Figure 14 shows the daily variability and the
mean diurnal variation of 1,2 dibromoethane at Denver (Site 7).
1,1,1 Trichloroethane is another large-volume chemical that may be a weak
mutagen (Table 3). The highest concentration of 2.7 ppb was measured at
Denver. The lowest levels of about 140 parts per trillion are reflective of
its geochemical background. The daily average dose was determined to be 42
u.g/day, 28 fig/day, 92 ng/day and 93 |ig/day at Sites 4,5,6 and 7 respectively
(Table 9). The diurnal behavior of 1,1,1 trichloroethane at three selected
sites is shown in Figure 15. It is interesting that while methylene chloride
shows an afternoon maximum at Riverside, 1,1,1 trichloroethane shows a mini-
mum. This is largely due to the superimposition of afternoon vertical mixing
on the downwind transport. The large concentrations of methylene chloride
indicate that the reduction in species concentration caused by vertical mixing
is overwhelmed by the high transport source. The diurnal variation of 1,1,2
trichloroethane is very similar to that of 1,1,1 trichloroethane (Figure 16),
even though its average levels are at least an order of magnitude lower.
500
I
'5 400
300
£ 200
xN
u
»N100
u
2 4 6
TIME — days
(a) CONCENTRATION
10
/WJ
c
g
1 200
»
&
I 150
a
5 100
xw
a 50
01 OU
U
o
1 • t 1 1
-
.
-
-i i > 1 1 ,.,,., r
10 15
TIME — hours
(b) VARIATION
20
25
Figure 14. Atmospheric concentration and mean diurnal variation
of 1,2 dibromoethane at Denver, CO, 16-26 June 1980.
36
-------
2000
•s 1500
1000
8 500
I
u
{ i I I - { i !
5 10 15 20
TIME — hour
(a) HOUSTON, TX — 15-24 MAY 1980
25
•c 1500
e
s. 1000
8 500
(*)
u
-111[ t •
5 10 15 20
TIME — hour
(b) DENVER. CO — 16-26 JUNE 1980
25
2000
= 1500
1000
n
O
o
O
500
III
It1
5 10 15 20
TIME — hour
(c) RIVERSIDE, CA — 2-12 JULY 1980
25
Figure 15. Mean diurnal variation of 1,1,1 trichloroethane.
37
-------
200
AW
1
5
S 1K>
!
i 100
1
0
N
z
O en
O, DO
0
X
0
A
i • i • i ' i
-
_
}y
T
!T T T
X 1 i ~
T T ' ' I
T *
1 [
1 . 1 . 1 . 1
0 5 10 15 20 25
TIME — hour
Figure 16. Mean diurnal variation of 1,1,2 trichloroethane
at Riverside, CA, 2-12 July 1980.
Extremely small amounts of tetrachloroethan.es were measured. The two
isomers (1,1,1,2 and 1,1,2,2) together were present at an average concentra-
tion of about 20 parts per trillion (Table 9). At no time did the concentra-
tion of either one of these isomers exceed 0.1 ppb. The symmetric isomer
(1,1,2,2) is found to be a bacterial mutagen and is suspected to be a carcino-
gen (Table 3). The asymetric isomer (1,1,1,2) has been tested for mutageni-
city with negative results (Table 3).
1,2 Dichloropropane was the only chlorinated propane measured. There was
also evidence of the presence of a chemical tentatively identified to be an
isomer of dichloropropene, but further tests are necessary to ascertain its
identity. Dichloropropane, like many of the chlorinated ethanes, is a bac-
terial mutagen (Table 3). Its concentrations were relatively uniform in all
cities except Houston, where concentrations as high as 0.25 ppb were measured.
Average concentrations were 0.08 ppb at Houston (Site 4) and between 0.05 ppb
and 0.06 ppb at all other sites. Average outdoor intake is determined to be
about 6 to 8 jig/day. Figure 17 shows the diurnal behavior of 1,2 dichloropro-
pane at Riverside.
Chloroalkenes
Six chloroalkenes were sought. Of these, allyl chloride (a suspected
carcinogen) was found to be present at concentrations of less than 5 parts per
trillion at all sites. Vinyledene chloride (a bacterial mutagen and a sus-
pected carcinogen) was measured at an average concentration of 10 to 30 parts
per trillion at all sites. It was below our limit of sensitivity (4 parts per
trillion) at approximately 30 percent of the time. The highest concentration
measured was 0.23 ppb. The low abundance of vinyledene chloride is at least
partially attributable to its rapid removal from the atmosphere (Sing et al.,
38
-------
I 200
i
5 150
UJ
2 100
&
o
I
S
X
3
U
S
10 15
TIME — hour
20
25
Figure 17. Mean diurnal variation of 1,2 dichloropropane
at Riverside, CA, 2-12 July 1980.
1979). Another equally reactive dichloroethylene (cis-1,2) was found to be
more ubiquitous. Concentrations of 1,2 dichloroethylene as high as 0.6 ppb
were measured in Denver. Average concentrations at all sites varied between
40 and 80 parts per trillion. Together the two dichloroethylenes add up to a
daily intake of 4 to 8 H-g/day. Unlike vinyledene chloride, the symmetric iso-
mer is not found to be a mutagen. No carcinogenicity data on 1,2
dichloroethylene are currently available (Table 3)*
One of the two dominant chloroethylenes in the atmosphere is trichloroe-
thylene. It is a large-volume chemical (annual U.S. emissions = 0.15 million
tons) that is also a suspected carcinogen. The highest concentration of 2.5
ppb was measured at Denver (Table. 9). The average concentrations were typi-
cally between 0.1 to 0.2 ppb. The atmospheric variability of trichloroethy-
lene is substantial and is due to both variable emissions and a very short
atmospheric lifetime (Singh et al., 1979). The diurnal behavior of trichloro-
ethylene at Sites 4, 6, and 7 is shown in Figure 18. The daily average out-
door intake is determined to lie between 15 |ag/day and 25 fig/day.
The second large-volume chloroethylene that is also a suspected carcino-
gen is tetrachloroethylene. Its annual U.S. emissions are estimated to be
about 0.3 million tons. At all sites the tetrachloroethylene atmospheric
abundance was 2 to 4 times that of trichloroethylene. This is due to larger
emissions as well as its much longer lifetime when compared to trichloroethy-
lene (Singh et al., 1979). The highest concentration of tetrachloroethylene
was 7.6 ppb. The daily average dose was determined to be between 60 and 80
|j.g/day at all sites. The diurnal behavior of tetrachloroethylene was similar
to trichloroethylene (Figure 19).
The sources of hexachloro-1,3 butadiene (HCBD) are secondary, since its
production appears to have stopped in the mid 1960s. It has also been
39
-------
1000
| 800
t
« 600
I
| 400'
n
0
5-200
0
(
( .,.,.,-
-
1
-
1 1
i. .:.]
Llhl.ir
) 5 10 15 ^20 2
TIME — hour
1000
| 800
'C
S. 600
| 400
n
O
5-200
0
C
(•) HOUSTON.
-
-
(
•'II
1 . i
5
1000
i soo
| 600
&
1 400
n
0*200
n
TX — 16-24 MAY 1980
I " f " 1 *
J
_
.llil. ..: "
10 16 20 25
TIME — hour
(b) DENVER. CO — 16-26 JUNE 1980
j j . , . i . I i
-
-
Mili^jih*.
5 10 15 20
TIME — hour
(c) RIVERSIDE, CA — 2-12 JULY 1980
25
Figure 18. Mean diurnal variation of trichloroethylene.
40
-------
1
i 150°
a
e
S. 1000
1
8* 500
IN
8
0
t " 1 1
-
•I. '.,[,,, I
-
-
1 • 1
1 — • — 1
0 5 10 15 20
TIME — hour
(a) DENVER. CO — 16-26 JUNE 1980
25
2UUO
I 1500
01
a
5
& 1000
I
I
N
o
«, 500
0
o
0
i • i ' i • i •
-
•I1:
i
i . i . r
• -
0 5 10 15 20
TIME — hour
(b) RIVERSIDE. CA — 2-12 JULY 1980
25
Figure 19. Mean diurnal variation of tetrachloroethylene.
identified in the effluents of sewage treatment plants. Recognized to be a
bacterial mutagen (Table 3), its average atmospheric abundance is quite low (2
to 10 parts per trillion). The daily average dose is estimated to be between
0.5 and 3 ng/day. No information is available on the reactivity of HCBD, but
its chemical structure would suggest that it is unlikely to be completely
inert.
Chloroaromatics
Six chloroaromatics were sought. No data are being reported of
p-dichlorobenzene because of unknown interferences. Monochlorobenzene was the
most dominant of the chlorobenzenes and its average concentration appeared to
be close to 0.3 ppb. The highest concentration was 2.8 ppb in Houston. This
is not inconsistent with its large source (0.1 to 0.15 million tons/year in
the United States) and its moderately long lifetime. Figure 20 shows the
diurnal variation of monochlorobenzene, which is typical of other species at
this site including m-dichlorobenzene (Figure 21). Both dichlorobenzenes
(m- and o-) together were present at an average concentration of 15 to 30
41
-------
1000
I 800
! 600
t
400
J*
10 15
TIME — hour
20
25
Figure 20. Mean diurnal variation of monochlorobenzene
at Denver, CO, 16-26 June 1980.
§
s
I
.40
£
1 30
1U
Z
IU
g 20
UJ
CO
0
l'°
0
5 o
i • i • i • i
•
.
.
.
11'
_
•p
' 1 I I ' I J "
r . , * .1 , 1. , * ^
10 15 20
TIME — hour
25
Figure 21. Mean diurnal variation of m-dichlorobenzene
at Denver CO, 16-26 June 1980.
42
-------
parts per trillion at all sites. Typically o-dichlorobenzene was somewhat
more abundant than m-dichlorobenzene. The highest measured concentrations of
o- and m-isomers were 0.23 ppb and 0.05 ppb respectively. 1,2,4 Trichloroben-
zene was ubiquitously present, but its concentration never exceeded 0.04 ppb.
Average intake was always less than 2 j/g/day. Figure 22 shows the diurnal
behavior of 1,2,4 trichlorobenzene (TCB) at Riverside. The diurnal pattern
was typical of other pollutants at this site. Toxicity data are not available
for most chlorobenzenes. ot-chlorotoluene, a suspected mutagen, was also
sought but was found to be present at average concentrations that were less
than 5 parts per trillion. Excursions in a-chlorotoluene were encountered,
and levels as high as 0.1 ppb were measured. Given the very low emission rate
of a-chlorotoluene (- 0.5 thousand tons per year in the United States) its
absence from the ambient atmosphere at average levels above 5 parts per tril-
lion is not surprising.
Aromatic Hydrocarbons
Eight aromatic hydrocarbons were sought. While benzene is suspected to
be carcinogenic (Table 3), the carcinogenicity of other aromatic hydrocarbons
is currently uncertain. The two most dominant aromatic hydrocarbons were ben-
zene and toluene. The average abundance of toluene exceeded that of benzene
at all sites: Average toluene/benzene concentration ratios at Sites 4, 5, 6,
and 7 were respectively 1.8, 1.1, 1.4, and 1.5. As the air masses aged (or in
cleaner environments) the toluene/benzene ratio decreases, largely because of
the longer lifetime of benzene compared to toluene (8 days versus 2 days).
Highest benzene and toluene concentrations of 38 ppb and 66 ppb were measured
in Houston. Benzene average intake at Houston was 450 fjg/day and 91 //g/day at
St. Louis. The toluene intake was correspondingly higher (Table 9).
A common source of all measured aromatic hydrocarbons was indicated, as
the diurnal variation of all the aromatic hydrocarbons at a given site
- 1UU
1
g
I 80
I
1
£ 60
Ul
N
Z
Ul an
to 40
O
EC
O
I 20
u
£
1 ' 1 ' 1 * 1
-
" —
PlH...if.ih:
ft 0 5 10 15 20 2J
TIME — hour
Figure 22. Mean diurnal variation of 1,2,4 trichlorobenzene
at Riverside, CA, 2-12 July 1980.
43
-------
was nearly identical. Figures 23 and 24 clearly show the nearly identical
diurnal behavior of benzene and toluene at individual sites. Figure 25 demon-
strates that other aromatic hydrocarbons also showed virtually identical diur-
nal behavior.
As a whole, the aromatic hydrocarbon group is the most dominant, and
daily intake of this group was the highest at all sites (Table 10).
Oxygenated Species
Four oxygenated species were sought: formaldehyde, phosgene, peroxyacetyl
nitrate (PAN), and peroxypropionyl nitrate (PPN). Liquid chromatographic
analysis of other aldehydes that are also toxic is currently underway. For-
maldehyde, a suspect carcinogen (Table 3), was measured at relatively high
concentrations that varied from 6 to 41 ppb. The abundance of formaldehyde
compared to most other carcinogens that were measured in urban atmospheres is
significant. It is also found to be a bacterial mutagen and a suspected car-
cinogen (Tables 3 and 4). Figure 26 plots the formaldehyde concentration data
obtained at Sites 5, 6, and 7. No clear diurnal trends are apparent. At
Riverside (Site 7) an afternoon maximum is evident. The daily dose of formal-
dehyde at Sites 5, 6, and 7 is determined to be 319 //g day, 347 ^g/day, and
536 fjg/day, respectively, which is higher than the daily dose of benzene at
these sites.
Phosgene was not detected at most sites, largely because the coulometer
also was used for analysis of PAN, and PPN. Rain at Houston and St. Louis
prevented the formation and accumulation of phosgene. Limited data from
Riverside suggests levels approaching 50 parts per trillion (still very low).
As is clear from Table 9, PANJand PPN levels were quite low at all sites.
This is largely attributable to the prevailing weather. Maximum PAN levels at
sites 4, 5, 6, and 7 were 4.4 ppb, 0.9 ppb, 11.5 ppb, and 5.6 ppb. The PPN
levels were roughly lower by a factor of 5 when compared to those of PAN.
Also, PPN was less than 10 parts per trillion a significant (30 to 50 percent)
fraction of the time. The diurnal variation of PAN shown in Figure 27 for
Riverside is somewhat typical of that area. It is pertinent to repeat here
that coulometric analysis was used for PAN and PPN determination: The quanti-
tative nature of the coulometric response of PAN and PPN has not been tested.
44
-------
25
20
It.
I
5
0
(
i • i
-
.'
i
' i
i
I
> 5 10
1 ' 1 '
-
1.1.
.15 20 21
25
TIME — hour
(a) HOUSTON. TX — 15-24 MAY 1980
20
*
a 15
jb 10
l!
5 10 15 20
TIME — hour
(b) DENVER, CO — 16-26 JUNE 1980
25
20
15
ll
! i
5 10 15 20
TIME — hour
(e) RIVERSIDE. CA — 2-12 JULY 1980
25
25
Figure 23. Mean diurnal variation of benzene.
45
-------
50
40
i
i
30
n
5
.* 20
?
J
10
n
_
-
-i
i • i ' i '
.
-
T
" | I I { I J { -
.. - , , . 1 ,
50
40
30
5 10 15 20
TIME — hour
(a) HOUSTON. TX — 15-24 MAY 1980
r°
£ 20
o*
10
5 10 15 20
TIME — hour
(b) DENVER. CO — 16-26 JUNE 1980
50
40
2
a
30
n
O
20
O*
10
5 10 15 20
TIME — hour
(c) RIVERSIDE, CA — 2-12 JULY 1980
25
25
25
Figure 24. Mean diurnal variation of toluene.
46
-------
56
52
48
44
40
36
25
i 20
a
I
1
in 15
z
111
x 10
i
E
5
n
1 ' 1 ' 1
_
.
i
_
3.
i
1
I
t
T
i
' i T
[III- I'
. 1 i ... i . i J- .
10 15
TIME — hour
20
25
Figure 25. Mean diurnal variation of m/p-xylene
at Houston, TX, 15-24 May 1980.
ui 32
O
I 28
LU
\ 24
1 20
O
"• 16
12
8
4
ST. LOUIS (5-7 JUNE 19801
DENVER (23-24 JUNE 1980)
RIVERSIDE (8-10 JULY 19801
02 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40
TIME — hours
Figure 26. Atmospheric concentrations of formaldehyde.
47
-------
4000
3500
c
o
1 3000
J 2500
^
I2000
| 1500
2
< 1000
a.
500
n
-
-
-
-
-
•
i
"5
1
i
5 1
i
1
i *
i
. •
1
i
^
i
-
-
-
i
•
-
-
I:
1 . I . 1 ^
10 15
TIME — hour
20
25
Figure 27. Mean diurnal variation of peroxyacetyl nitrate (PAN)
at Riverside, CA, 2-12 July 1980.
48
-------
SECTION 7
FUTURE RESEARCH PLANS
The second-year research effort was completed successfully as planned.
To date data for a large number of selected toxic chemicals have been col-
lected from seven cities:
• Los Angeles, California
• Phoenix, Arizona
• Oakland, California
• Houston, Texas
• St. Louis, Missouri
• Denver, Colorado
• Riverside, California.
In the third (final) year of this project, a significant emphasis will be
placed on field measurements and on analysis and interpretation of the data
set collected during this study. The major effort"in the third year will be
devoted to:
• Expanding the list of toxic chemicals to be measured
• Conducting additional field studies in selected U.S. cities
• Analyzing and interpreting all collected field data
• Preparing a final report.
During the end of the second year and early part of the third year of
research efforts will be directed to developing measurement methods for
ambient aldehydes and ketones (as well as formaldehyde, which was measured in
the second year). A high-pressure liquid chromatograph (HPLC) has been
acquired and will be utilized. The test methods are similar to those utilized
by Kuwato et al. (1979). Attempts to identify currently unidentified species
that have been found to be nearly ubiquitously present will continue, and we
will try to improve the separation of chlorinated aromatics (especially
49
-------
The following four cities have been tentatively identified as field site
locations for the third year:
• New York City, New York
• Cleveland, Ohio
• Philadelphia, Pennsylvania
• Chicago, Illinois.
Three of these will be selected after discussions with the project officer.
The literature search will continue as will the analysis of collected data.
We expect to begin preparation of a comprehensive final report dealing with
the abundance, intake, sources, sinks and effects of toxic chemicals.
50
-------
REFERENCES
Helmes, C.T. et al., 1980: "Evaluation and Classification of the Potential
Carcinogenicity of Air Pollutants," SRI International, NCI Contracts
N01-CP-33285 and 95607, Menlo Park, California.
McCann, J., and B.N. Ames, 1977: "The Salmonella/Microsome Mutagenicity Test:
Predictive Value for Animal Carcinogenicity," in Origins of Human Cancer,
Cold Spring Conference on Cell Proliferation, Volume 4, 1431-1450.
U.S. Public Health Service, 1965: "Selected Methods for the Measurement of
Air Pollutants," Publication 999-AP-ll, Cincinnati, Ohio.
Singh, H.B., L.J. Salas, A. Smith, H. Shigeishi, 1979: "Atmospheric Measure-
ments of Selected Toxic Organic Chemicals," Interim Report, SRI Project
7774, prepared for U.S. Environmental Protection Agency, Menlo Park, Cal-
ifornia.
Kuwato, K., M. Vebori, and Y. Yamasaki, 1979: "Determination of Aliphatic and
Aromatic Aldehydes in Polluted Airs as their 2,4-dinitrophenylhydrazones
by High Performance Liquid Chromatography," J. of Chr. Sci., Vol. 7, pp.
264-268.
Padgett, H.J., 1979: "List of Chemicals Assessed Weight of Carcinogenic Evi-
dence," memorandum from Joseph Padjett, Office of Air Quality Planning
and Standards, U.S. Environmental Protection Agency, Research Triangle
Park, North Carolina.
51
------- |