AMBIENT AIR QUALITY STANDARD FOR OZONE
("MINOR" REPORTS)
Tab A - Revisied Ozone Standard - (part 50 Notice)
B - Calibration Package (Part 50 Notice)
C - Implementation Regulations (Part 51 Notice)
D - Federal Register Notice of 6/22/78
E - Summary of Contents (PEDCo)
J - Summary Statement from the EPA Advisory Panel on Health
Effects of Photochemical Oxidants
L - Alternative Forms of the Ambient Air Quality Standard for
Photochemical Oxidants
Q - The Use of Judgemental Probobility Distribution in Setting
NAAQS for Ozone
S - CWPS/RARG Report
T - Memo form Walt Barber to Dave Hawkins (re: CWPS/RARG Report)
U - Estimates of Economic Benefits Associated with Alternative
Secondary Ozone Standards (Under Revision)
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11/21/73
ENVIRONMENTAL PROTECTION AGENCY
(40 CFR Part 50)
(FRL Docket Number OAQPS 78-8)
PHOTOCHEMICAL OXIDANTS
Revisions to the National Ambient Air
Quality Standard
AGENCY: Environmental Protection Agency.
ACTION: Final Rulemaking.
SUMMARY: In accordance with the provisions of Sections 108 and 109
of the Clean Air Act as amended, EPA has conducted a review of the
criteria upon which the existing primary and secondary photochemical
oxidant standards are based. These standards were promulgated in 1971
(36 FR 8186) and were both set at an hourly average IGVO! of 0.08 part
per million (ppm) not to be exceeded more than 1 hour per year. On
June 22, 1978, EPA proposed changes in the standard (43 FR 26962)
based on the findings of the revised criteria. The proposed changes in-
cluded (1) raising the primary standard to 0.10 ppm, (2) retaining the 0.08
ppm secondary standard, (3) changing the chemical designation of the standard
from photochemical oxidant to ozone, and (4) changing to a standard with a
statistical rather than deterministic form. The final rulemaking will make
two further changes in the standard; (1) raising the secondary standard to
0.10 ppm, and (2) changing the definition of the point at which the standard
is attained to "when the expected number of days per calendar year with maxi-
mum hourly average concentrations above 0.10 ppm is equal to or less than
one."
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FOR FURTHER INFORMATION CONTACT:
Mr. Joseph Padgett, Director
Strategies and Air Standards Division
Office of Air Quality Planning and Standards
U.S. Environmental Protection Agency, RTP, NC 27711
Telephone: 919-541-5204
AVAILABILITY OF RELATED INFORMATION: A docket (Number OAQPS 78-8) con-
taining information used by EPA in revising the standards is available
for public inspection and copying between 8:00 a.m. and 4:30 p.m.
Monday through Friday, at EPA's Public Information and Reference Unit,
Room 2922, Waterside Mall, 401 M Street SW., Washington DC 20460. These
materials include the "Air Quality Criteria for Ozone and Other Photo-
chemical Oxidants" and "Control Techniques for Volatile Organic Emissions
from Stationary Sources," both of which were issued simultaneously when
this standard was proposed. The Control Techniques Document and staff
papers pertaining to the form of the ozone standard, risk assessment
method, secondary standard, and health panel assessment are available
upon request from Mr. Joseph Padgett. Statements of the environmental,
economic, and energy impacts of implementing this standard revision are
also available upon request from Mr. Joseph Padgett, at the address
shown above. The Air Quality Criteria Document can be obtained from:
Mr. Michael Berry
Environmental Criteria and Assessment Office, MD-52
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
Telephone: 919-541-2266
Revisions to 40 CFR Part 50, Appendix D, "Measurement Principle and
Calibration Procedure for the Measurement of Photochemical Oxidants Cor-
rected for Interferences Due to Nitrogen Oxides and Sulfur Dioxide"
and Appendix H, "Interpretation of the National Ambient Air Quality
CH. ,^,^ *n n^nnp» are described elsewhere in this preamble.
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Revisions to 40 CFR Part 51, substituting the word "ozone" for
"photochemical oxidants" throughout that part, and to Section 51.14,
pertaining to control strategies, are being promulgated by EPA elsewhere
in this issue of the Federal Register.
SUPPLEMENTARY INFORMATION:
BACKGROUND
On April 30, 1971, the Environmental Protection Agency
promulgated in the Federal Register (36 FR 8186) National Ambient
Air Quality Standards for photochemical oxidants. The scientific,
technical, and medical bases for these standards are contained in the
air quality criteria document for photochemical oxidants, published by
the U.S. Department of Health, Education, and Welfare in March, 1970.
Both the primary and secondary standards were set at an hourly average
level of 0.08 ppm not to be exceeded more than once per year. The
preamble to the regulation stated:
"The revised national primary standard of 0.08 ppm is based
on evidence of increased frequency of asthma attacks in some
asthmatic subjects on days when estimated hourly average concen-
trations of photochemical oxidant reached 0.10 ppm. A number
of comments raised serious questions about the validity of
data used to suggest impairment.of athletic performance at lower
oxidant concentrations. The revised primary standard includes a
margin of safety which is substantially below the most likely
threshold level suggested by this data. It is the Administrator's
judgment that a primary standard of 0.08 ppm as a 1-hour average
will provide an adequate safety margin for protection of public
health and will protect against known and anticipated adverse
effects on public welfare."
The asthma study cited as evidence for the original study is oased on
work by Schoettlin and Landau. As discussed in the June 22, 1978, pro-
posed revision to the original standard, EPA has reassessed its conclusions
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regarding this study. This reassessment, plus the evaluation of medical
evidence generated since 1970, led EPA to propose, on June 22, 1978, a
revised primary standard of 0.10 ppm (43 FR 26962). EPA did not
propose a change in the secondary welfare standard at that time. The
proposal was accompanied by publication of revised criteria and control
techniques documents, as well as various staff papers relating to the
standard itself and to implementation of the standard. EPA solicited written
comments on the proposed standard and, to accept oral testimony, sponsored
four public hearings (Washington, D. C. - July 18; - Atlanta, Ga. - August 17;
Dallas, Tex. - August 22; Los Angeles, Calif. - August 24).
Oxidants are strongly oxidizing compounds, which are the primary
constituents of photochemical smog. The oxidant found in largest
amounts is ozone (0.,), a very reactive form of oxygen. Oxidants also
include the group of compounds referred to collectively as peroxyacyl-
nitrates (PANs) and other compounds, all produced in much smaller
quantities than ozone.
Most of these materials are not emitted directly into the atmosphere
but result primarily from a series of chemical reactions between
oxidant precursors (nitrogen oxides and organic compounds) in the
presence of sunlight. The principal sources of organic compounds are
the hydrocarbon emissions from automobile and truck exhausts, gasoline
vapors, paint solvent evaporation, open burning, dry cleaning fluids,
chemical plants and other industrial operations. Nitrogen oxides are
emitted primarily from combustion sources such as electric power
generation units, gas and oil-fired space heaters, and automobile,
diesel and jet engines.
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The reductions in emissions of nitrogen oxides and organic
compounds are achieved through Federal and State programs that have
been formalized in regulations promulgated under the Clean Air Act.
The Federal programs provide for the reduction in emissions nationwide
through the Federal Motor Vehicle Control Program, the Federal
program for control of aircraft emissions, National Emission Standards
for Hazardous Air Pollutants, and the development of New Source
Performance Standards. The State programs provide for additional
control measures through State Implementation Plans in those areas of
the country where the Federal programs are not sufficiently stringent
to permit attainment of air quality standards.
LEGISLATIVE REQUIREMENTS AFFECTING THIS PROMULGATION
Two sections of the Clean Air Act govern the development of a
National Ambient Air Quality Standard. Section 108 instructs EPA to
document the scientific basis for the standard, and Section 109 provides
guidance on establishing standards and reviewing criteria.
Air quality criteria are required by Section 108(a)(2) to reflect
accurately the latest scientific information useful in indicating the kind
and extent of all identifiable effects on public health or welfare that
may be expected from the presence of the pollutant in the ambient air.
The Administrator is required to propose, simultaneously with the
issuance of these criteria, primary and secondary ambient air quality
standards based upon such criteria. The primary standard is defined in
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Section 109(b)(l) as that ambient air quality standard the attainment
and maintenance of which in the Administrator's judgment, based en such
criteria and allowing an adequate margin of safety, are requisite
to protect the public health. The secondary standard (Section 109(b)(2))
must specify a level the attainment and maintenance of which in the Admini-
strator's judgment, based on such criteria, are requisite to protect
the public welfare from any known or anticipated adverse effects associated
with the presence of the pollutant in the ambient air. These adverse
welfare effects, which are discussed in Section 302(h) of the Act, include
effects on soils, water, crops, vegetation, man-made materials, animals,
weather, visibility, hazards to transportation, economic values, personal
comfort and we11-being, and other factors.
The Clean Air Act specifies that National Ambient Air Quality
Standards are to be based on scientific criteria relating to the
level that should be attained to protect public health and welfare
adequately. Considerations of cost of achieving those standards or the
existence of technology to bring about needed reductions of emissions
are not germane to such a determination, as the words of the Act and its
legislative history clearly indicate. Section 109(d) directs the
Administrator to complete a review of all existing standards and
criteria before the end of 1980 and at 5-year intervals thereafter
and to revise them in whatever manner that review reveals is necessary.
This promulgation is the result of such a review.
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Assuring attainment and maintenance of ambient air quality
standards Is the responsibility of the states. Under Section 110 of
the Act, they are to submit to EPA for approval State Implementation
Plans (SIPs) that provide for the necessary legal requirements for
sources of the relevant pollutant so as to demonstrate attainment and
maintenance of the standards by certain deadlines. In many areas of
the country the ambient air quality standards are not being attainea,
despite the fact that the deadline for attainment has long since
passed. As a remedy, Part D of the Act requires states with
violations of ambient air quality standards to submit revised SIPs
to ensure attainment of the standards and to meet certain new
requirements of Part D by January 1, 1979. (Section 129(c),
Publ. L. 95-95, note under 42 U.S.C. 7502.) The Act does not
authorize the Administrator to extend that deadline, and consequently
this revision of the photochemical oxidant standard does not affect the
deadline for submittal of SIP revisions.
A state that submits a revised SIP meeting the requirements of
Part D by January 1, 1979, will escape the consequences of §§ llOfa) (2.) 1(1)
and 176(a) of the Act, even if the target standard of the plan is
0.08 ppm. Attainment of 0.08 ppm will ensure attainment of 0.10 ppm.
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There may be cases, however, where states will wish to revise
their newly submitted SIPs to reflect the change in the standard.
For example, where the air quality in a state is close to 0.10 ppm, a
plan that ensures attainment of a 0.08 ppm standard by 1982 may require
controls that a 0.10 ppm standard would render unnecessary. These states
may want to revise their SIPs before the controls take effect. Such
revisions can be accomplished quickly, since the difficult and time-
consuming tasks of developing an emission inventory and weighing the
reduction capabilities of various possible measures have already been
accomplished.
In many cases, revisions of this type are expected to be un-
necessary. States that cannot demonstrate attainment before 1982 must
include in their 1979 submittals measures sufficient to demonstrate
reasonable further progress through 1982, but need not
include measures that demonstrate attainment until the SIP is further
revised in 1982. Where the 1979 plan does not contain measures demon-
strating attainment, the minor shift in the target from 0.08 to 0.10 ppm
should not affect the 1979 requirements.
The time schedule of any SIP revisions occasioned by the raising
of the standard will be determined by the states. Section 110(a)(l)
requires that SIP revisions be submitted within 9 months after a
standard is revised. This, however, refers to situations where a
standard is tightened so that existing SIPs no longer show attainment.
Where a standard is relaxed, no SIP revision is required by the law,
since states may have more stringent controls than necessary if they
choose. Thus, there is no deadline. On the other hand, those states
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that do elect to revise their SIPs will undoubtedly act as quickly
as possible, for the reasons discussed above.
SUMMARY OF GENERAL FINDINGS FROM AIR QUALITY CRITERIA FOR
OZONE AND PHOTOCHEMICAL OXIDANTS
On April 20, 1977 (42 FR 20493), EPA announced that it was in
the process of reviewing and updating the 1970 criteria document
for photochemical oxidants in accordance with provisions of Section 109(d)(l)
of the Clean Air Act as amended. The notice called for information and
data that would be helpful in revising the document. In the process of
developing the criteria document, EPA has provided a number of opportunities
for external review and comment. Two drafts of the criteria document
have been made available for external review and EPA has received more
than 50 written comments on the first draft and approximately 20 on the
second draft. The American Petroleum Institute has submitted extensive
information that EPA has considered in this standard review. The
criteria document was the subject of two meetings of the Subcommittee
on Scientific Criteria for Photochemical Oxidants of EPA's Science
Advisory Board. Each of these meetings has been open to the public
and a number of individuals have presented both critical review and new
information for EPA's consideration. A full discussion of comments
received during the review process as well as EPA's disposition of
these comments can be found in the docket (OAQPS 78-8) assembled for
this rulemaking.
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From the extensive review of scientific information presented in
the criteria document, findings in several key areas have particular
relevance for setting the ozone standard.
1. The concept of a "threshold" may not be an appropriate term
for describing the impact of ozone on human health. Since
"thresholds" will depend upon who is studied and what is measured,
it is unlikely that scientific evidence for a specific effects
threshold can be satisfactorily derived for protecting public
health. Limited studies can be performed on groups of unusually
sensitive persons. Most experimental studies of humans are
performed on small numbers of healthy subjects who do not
adequately reflect the range of human sensitivity. Animal exposure
studies usually cannot provide appropriate models of sensitive
human populations. Thus, "thresholds" for sensitive persons
are difficult or impossible to determine experimentally, while
the "threshold" for healthy persons or animals is not likely to be
predictive of the response of more sensitive groups.
2. Ozone is a broncho-pulmonary irritant which affects the respiratory
mucous membranes, other lung tissues and respiratory functions. It
has been demonstrated in clinical and epidemiological studies that
ozone impairs the normal mechanical function of the human lung and causes
clinical symptoms such as chest tightness, cough and wheezing. These
effects may occur in sensitive individuals at short-term ozone concen-
trations between 0.15 and 0.25 ppm. The clinical studies data base on
these effects is far more extensive than that available in 1970 and
these effects have been demonstrated at lower levels than those
cited in the 1970 criteria document.
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3. The best available evidence suggests that an elevated proportion
of asthmatics experience attacks on days when the peak hourly oxidant
concentrations reach about 0.25 ppm. This finding is based on a
revaluation of the Schoettlin and Landau study and represents, a
revision of the 0.10 ppm estimate made in the 1970 criteria document.
4. The key finding from toxicologic studies is the increased
susceptibility to bacterial infection in laboratory animals
exposed to 0.10 ppm ozone and a bacterial challenge. Infection
rates are lower for animals exposed only to the bacterial
challenge. Other effects such as biochemical changes, morpho-
logical abnormalities, and genetic changes have been shown in
some animal studies but the physiological significance of these
effects remains to be established.
5. There is a limited amount of data that suggests that ozone
may accelerate the aging process in living organisms. Exposure
of rabbits to unspecified concentrations of ozone for one hour
per week for a year has been reported to induce premature aging
symptoms such as premature cartilage calcification, severe
depletion of body fat, and general signs of aging.
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6. The fact that ozone exposure is frequently accompanied by
exposure to other pollutants, such as sulfur dioxide (S02), has
prompted several investigators to conduct laboratory evaluations
of exposure of humans to combinations of 0-, and other pollutants.
Exposures to 0.37 ppm 0, and 0.37 ppm SOg simultaneously have
been reported to produce larger changes in pulmonary function
than does either pollutant alone. Other simultaneous exposure
tests using 0.25 ppm 0., and 0.3 ppm nitrogen dioxide (N02), as well as
0,, NOp, and 30 ppm carbon monoxide (CO), showed no obvious effects.
Nevertheless, the SO^ - 0^ synergism findings support the need for an
adequate margin of safety.
7. There are no studies that link exposure to ozone or
photochemical oxidants to an increase in human mortality. A number
of epidemiologic studies have been designed and conducted to demon-
strate this effect, but all have been negative or inconclusive.
8. Ozone accelerates the aging of many materials resulting in rubber
cracking, dye fading and paint erosion. These effects are related
to the total dose of ozone and can occur at very low levels,
given long duration exposures. Damage to vegetation occurs as
leaf injury, decreased growth and yield, and disruption of
reproductive functions.
9. All evidence presently available indicates that around urban
centers with severe oxidant problems, the major concern is the forma-
tion of photochemical oxidants from man-made organic and nitrogen oxide
emissions. Control of these emissions will result in significant
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reductions in ambient ozone, peroxyacetylnitrate (PAN), aldehydes
and photochemical aerosol.
RULEMAKING PETITIONS
The Agency was petitioned by the American Petroleum Ins-titute (API) and
29 member companies on December 9, 1976, and the City of Houston on
July 11, 1977, to revise the criteria, standards and control strategy
guidelines for photochemical oxidants. These efforts were already
underway when both petitions were filed, and the Agency responded
that it was deferring decision on their petitions until the rulemak'ing
was completed. EPA considers this final rulemaking and the accompanying
one on control strategy guidelines to be the Agency's final action on
these petitions. A summary of the two petitions and EPA's response is
summarized below.
The API petition requested that EPA revise the air quality criteria
document for photochemical oxidants in light of new information regarding
the causes, effects, and extent of air pollution attributed to ozone and
other oxidants. EPA has published a revised air quality criteria
document for photochemical oxidants which in the Agency's judgment
accurately reflects the latest scientific information regarding the
causes, effects, and extent of air pollution attributed to ozone and
other oxidants.
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The second request in the API petition was that EPA establish
a national primary ambient air quality standard based on new studies
which allegedly demonstrate no significant adverse human health
effects at or below ozone levels of 0.25 ppm for two-hour exposures.
The Agency has, as requested by API and as required under the Clean
Air Act, considered all new studies published since 1971 that are
relevant to setting a revised primary standard the attainment and
maintenance of which would,in the Administrator's judgment, protect the
public health with an adequate margin of safety. EPA differs with API's
conclusion that new studies conducted since 1971 demonstrate no signifi-
cant adverse human health effects at or below 0.25 ppm. A more detailed
discussion of EPA's judgments regarding reported or probaDle health
consequences at concentrations below 0.25 ppm is presented in the
rationale for revising the primary standard and in tne response to
comments, which appear elsewhere in this notice.
The third request by API was that the national secondary ambient
air quality standard be based on adverse effects on public welfare
as indicated by studies using ozone-specific measurement methods. In
addition, API urged the Agency to take into account the full range of
economic and social considerations which define the "public welfare"
as described under Section 302(h) of the Clean Air Act. Since the
proposal of June 22, 1978, EPA has added to its assessment an analysis
of the estimated economic benefits of a secondary standard more stringent
than the primary. Based on this analysis as well as effects data
presented in the criteria document, EPA has concluded that a secondary
standard more stringent than the primary standard does not appear
necessary.
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Both the API and Houston petitions requested EPA to state the
primary and secondary standards so as to permit reliable assessments of
compliance. EPA agrees that the present deterministic form of the oxidant
standard has several limitations and has made reliable assessment of
compliance difficult. The revised ozone air quality standards are
stated in a statistical form which will more accurately reflect the
air quality problems in various regions of the country and allow more
reliable assessment of compliance with the standards.
The API and Houston petitions requested that EPA specify the use
of an appropriate measurement method for the monitoring of ambient
concentrations of ozone. API suggested the use of ethylene chemilumi-
nescence calibrated by either gas phase titration (GPT) or ultraviolet (UV)
photometry. As a result of EPA's continuing evaluation of several
calibration techniques the Agency has defined the reference method to
be ethylene chemiluminescence calibrated by UV photometry.i(See amendment
to Part 50, Appendix D in this edition of the Federal'Register.) EPA is
allowing the use of a modified version of trie current calibration method
(acidified KI) as an interim measure to avoid problems whicn would result
from immediate conversion to UV photometry.
Both the API and Houston petitions requested revision of the State
implementation plan (SIP) requirements to: (1) delete the assumption
of no background concentration of photochemical oxidants; and (2) specify
more reliable, alternative oxidant prediction relationships to replace
Appendix J for determining the degree of necessary precursor emission
reductions.
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EPA realizes that background concentrations and transport of ozone
from upwind locations can impact upon high levels of ozone in or near
an urban area during the afternoon hours. Therefore, several revisions
are being made in control strategy and implementation guidelines for
ozone. The revised guidelines set forth procedures for consideration
of both upwind transport and irreducible natural background by the States
in calculating the necessary reductions in hydrocarbon emissions. In
response to the second request, EPA nas determined that Appendix J of
40 CFR 51 no longer represents an acceptable analytical relationship
between hydrocarbons and ozone. Appendix J is therefore being deleted.
EPA will now allow States to use any of four analytical techniques to
determine the amount of hydrocarbon reduction necessary to demonstrate
attainment of the national ozone air quality standards. The four tech-
niques include: (1) Photochemical Dispersion Models, (2) Empirical
Kinetics Modeling Approach (EKMA), (3) Empirical and Statistical Models,
and (4) Proportional Rollback. These four techniques are discussed
further in the revision of Part 51 which appears elsewhere in this edition
of the Federal Register.
The Houston petition requested that: EPA consider information in their
petition relative to atmospheric conditions and other factors tnat affect
photochemical oxidants in the Houston area. The petition claimed that
the air pollution problems in Houston warrant special attention in
standard-setting and "tailor-made" control strategies, because the emis-
sion and meteorology situations and the overall pollution picture in that
area are "unique".
In response to the above claim, it should be noted tnat the majority
of the data presented in the revised criteria document is baseci on
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ozone exposure. Nearly all of the clinical and toxicological
studies are based on the effects of ozone. The biomedical data also
suggest that many of the effects observed during periods of elevated
photochemical oxidant concentrations are reasonably attributable primarily
to ozone in the ambient air. Since the primary and secondary standard
are based on the effects of ozone, the differences between areas in their
overall photochemical oxidant mixtures do not bear upon the setting of
national ozone air quality standards.
EPA agrees with the Houston petition that components of the photochemical
oxidant mixture other than ozone may have an adverse impact on health and/or
welfare. However, the data base is not sufficient at this time to
justify a separate standard for PAN or other non-ozone oxidants.
While EPA does not propose to establish separate standards for the
non-ozone constituents of the mixture at this time, those measures
taken to reduce ozone precursor emissions will also reduce PAN and
other non-ozone oxidant concentration levels. Finally, in response
to Houston's request for a unique standard based on their local
situation, it must be realized that the Clean Air Act does not
contemplate separate standards for different cities. The Act, dealing
in terms of national ambient air quality standards, has charged EPA to
identify the air quality levels wnich must be attained and maintained
to assure, with an adequate margin of safety, that adverse health
effects will not occur.
The Houston petition also requests that EPA "include realistic
requirements for the reduction of oxides of nitrogen as conditions
in the Houston area may indicate to be necessary to achieve the
revised standards." EPA's response is that it is the responsibility
of the State of Texas and the City of Houston to submit State
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implementation plan provisions tailored to the situation prevailing in
Houston. If the current SIP is not representative of the most efficient
means of reducing ozone in Houston, then, with Houston's assistance, Texas
should submit a revision which is consistent with local emission and
meteorological conditions.
SUMMARY OF COMMENTS RECEIVED
EPA has solicited public comment and critique on proposed
revisions to the photochemical oxidant air quality standard during all
phases of the standard development process. Prior to proposal, (April 20,
1977 - 42 FR 20493) EPA announced it was reviewing and updating the
criteria document and called for information that might be helpful in
revising the document. Public comments were received on two drafts of the
criteria document and the public was invited to two meetings of the Sub-
committee on Scientific Criteria for Photochemical Oxidants of EPA's
Science Advisory Board. In addition, a public meeting was held on
January 30, 1978, to receive comments from interested parties prior to
development of any formal agency position on the initial proposed revision
of the standard. The results of this meeting are discussed in the proposed
regulation (43 FR 26970) and a transcript of the meeting is available in the
OAQPS Docket 78-8.
Following proposal, EPA held four public meetings to receive comments
on the proposed standard revisions. Meetings were held in Washington, DC -
July 18, Atlanta, GA - August 17, Dallas, TX - August 22, and
Los Angeles, CA - August 24; transcripts are available in OAQPS Docket
78-8. In addition, 167 written comments were received during the formal
comment period which extended through October 16, 1978.
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The principal comments and Agency responses are discussed in the
following paragraphs (individual responses to comments are contained in
OAQPS Docket 78-8). EPA "also received comments on the proposed standard
after October 16. Although EPA does not have a legal obligation to review
these comments, we have addressed and responded to all significant issues
raised in the post-October 16 comments as part of the discussion of
comments in this preamble. As with all other documents considered o»- examined
by EPA as part of its decision process, these documents have been placed
in the public docket and have become part of the administrative record of
this decision.
The majority of comments received (127/167) opposed EPA's proposed
standard revision, suggesting either a more relaxed or a more stringent
standard. State air pollution control agencies generally supported a more
relaxed standard of 0.12 ppm or higher. State and Territorial Air Pollu-
tion Program Administrators (STAPPA) supported a standard lavel of 0.12 ppm,
municipal groups 0.12 ppm.or higher,and industrial groups 0.15 ppm or higher.
Environmental groups encouraged EPA to retain the 0.08 ppm st*nHarH.
Comments on the proposed revisions were received from five Federal
agencies. Three of the agencies endorsed the proposed primary standard
but one of these agencies requested that EPA consider formulating the
standard on a daily maximum hourly average basis. Another agency expressed
concern that EPA had inadequately substantiated the rationale for
raising the primary standard level and requested that the final revisions
provide further analysis in this regard. Finally, the Executive Office of
the President/Council on Wage and Price Stability through the Regulatory
Analysis Review Group suggested that the proposed standard was unnecessarily
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stringent and recommended an alternative methodology for setting the
primary standard that focuses on the marginal costs per person-hour
of ozone effects avoided.
Groups and individuals submitting comments are identified below:
COMMENTS RECEIVED ENDORSING CURRENT PRIMARY STANDARD
LEVEL OF .08 ppm
Organizations and Agencies
American Lung Association of Colorado
American Lung Association of Colorado, West Region
American Lung Association of Louisiana
American Lung Association of New Jersey
American Lung Association of New York State, Inc.
Bangor-Brewer TB and Health Association, Maine
California Lung Association
Connecticut State Department of Health
Environmental Confederation of Southwest Florida
Environmental Defense Fund
Ms. Nancy C. Fahden, Supervisor District Two, Contra Costa County (Calif.)
Board of Supervisors
Florida Lung Association
Green leaf Nurseries, Warsaw, IN
Issac Walton Teag"ue~Man~asbta Chapter"
League of Women Voters of the U.S.
League of Women Voters of Dallas, Texas
Maine Health Systems Agency
Maine Lung Association
Medford-Ashland Air Quality Maintenance Advisory Committee, Oregon
Michigan Lung Association
Michigan Lung Association, Saginaw Valley Region
National Air Conservation Commission, American Lung Association
Natural Resources Advisory Committee, Cedar Grove, N.J.
New Mexico Lung Association
Oregon Environmental Council
Oregon Lung Association
Queensboro Lung Association, Jamaica, N.Y.
Sierra Club
Sierra Club, Houston Chapter
South Shore (Ohio) Christmas Seal Association
Southwestern Ohio Lung Association
U.S. Department of the Interior
Washington Air Quality Coalition
Yale Environmental Law Association
Summary:
35 comments from organizations, agencies or their representatives ana
38 comments from concerned citizens supporting the current
primary standard level of .08 ppm.
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COMMENTS RECEIVED ENDORSING PROPOSED PRIMARY STANDARD
LEVEL OF .10 ppm
Organizations and Agencies
Air Pollution Control League of Greater Cincinnati
Air Quality Advisory Committee, California Department of Health
California Air Resources Board
.Coalition of Labor and Business (COLAB)
Co.lor.ado. Department of Health
Connecticut Department of Environmental Protection
MasSjachusetts_Dep_artment of Environmental Qualjty Engineering"
Public Health Ser vice /U.S." Department of"HEW
Regional Planning Commission for Jefferson, Orleans, St. Bernard and
St. Tammary Parrishes, Louisiana
Rhode Island Lung Association
Southern Alameda County Board of Realtors, California
U.S. Department of Energy
U.S. Department of Transportation
Wasatch Front Regional Council, Utah
Wayne County Department of Health, Michigan
Wisconsin State Department of Natural Resources
Summary:
16 comments from organizations, agencies or their
.representatives and 1 comment, from a concerned citizen
endorsing the proposed primary standard level of .10 ppm.
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COMMENTS RECEIVED ENDORSING A PRIMARY STANDARD LEVEL OF
.12 ppm
State and Local Agencies
Alabama Air Pollution Control Commission
City of Philadelphia, Pennsylvania
Georgia Department of Natural Resources
Griffith, Berkely, Charleston, Dorchester Council of Governments, S.C.
Indiana State Board of Health
Kansas Department of Health and Environment
Kentucky Department for Natural Resources and Environmental Protection
Maryland Environmental Health Administration
Michigan Department of Natural Resources
Nebraska Department of Environmental Control
Nevada Department of Conservation and Natural Resources
New York Department of Environmental Conservation
North Carolina Department of Natural Resources and Community Development
Pennsylvania Department of Environmental Resources
Tennessee Department of Public Health
Utah Bureau of Air Quality
Virginia Air Pollution Control Board
Organizations and Companies
Area Cooperation Committee of Tidewater and Virginia Peninsula Chambers
of Commerce
Evansville, Indiana, Chamber of Commerce
Sierra Pacific Power Company
State and Territorial Air Pollution Program Administrators
Texas Oil Marketers Association
Vulcan Materials Company, Wichita, KS
Summary:
17 comments from State and local agencies and 6 comments from
organizations and_corjprAtions.sup_pgr^ijg^_pjQmary standard
level of .12 ppm.
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23
COMMENTS RECEIVED ENDORSING A PRIMARY STANDARD LEVEL HIGHER
THAN .12 ppm AND/OR PROPOSED STANDARD TOO STRINGENT
Organization or Agency
Endorse Standard
Higher than .12
ppm
American Petroleum Institute (API)
Association of Local Air Pollution Control Officials
Associated Building Industry of Northern California
Cook County Dept. of Environmental Control, Illinois
Dow Chemical Company
General Motors Corporation
Great Plains Legal Foundation
Greater San Antonio Ch amber of Commerce, Texas
Houston Chamber of Commerce, Texas
Iowa-Illinois Gas and Electric Company
Louisiana Air Control Commission
Manufacturing Chemists Association
Monsanto Chemical Intermediates Co.
Motor Vehicle Manufacturers Assoc.
National Flexible Packaging Association
New Orleans Public Service, Inc.
Oklahoma State Dept. of Health
Owens-Illinois
Packnett, Steams-Roger, Inc.
Rio Blanco Oil Shale Company
San Antonio Metropolitan Health District, Texas
St. Louis County, Missouri
Shell Oil Company
Tennessee Eastman Corp.
Texas Air Control Board
Texas Chemical Council
U.S. Council on Wage and Price Stability
Utah Manufacturers Assoc.
Virginia Air Pollution Control Board
Western Oil and Gas Assoc.
White River Shale Project
X
X
X
X
X
X
X
X
X
X
X
Proposed Standard
Too Stringent
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Summary:
14 comments from organizations, agencies, and companies supporting
a primary standard level higher than .12 ppm,
4 comments from concerned citizens supporting a primary standard level
higher, .than. ...12 ppm. and. 23 comments stating the proposed standard
is too stringent.
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The principal issues raised during the comment period relate to
the following topics:
I. HEALTH EFFECT CRITERIA AND SELECTION OF PRIMARY STANDARD
- Definition of an Adverse Health Effect
- EPA's Interpretation of Cited Studies
- Margin of Safety
- Use of Animal Studies
- Exposure of Sensitive Groups
- Synergistic Effects and Chemical Species of the Standard
II. RISK ASSESSMENT METHOD
III. WELFARE EFFECTS AND SECONDARY STANDARD
IV. IMPLEMENTATION AND ATTAINABILITY
- Value of Hydrocarbon Control Questioned
- Timing of SIP Submissions
- Cost of Control Should Be Considered in Setting Standard
- Natural Background
V. PROCEDURAL ISSUES
A review of the comments received and their disposition has been
placed in the rulemaking docket (OAQPS 78-8) for public inspection.
The following sections summarize the significant comments and present
the Agency's responses.
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Definition of an Adverse Health Effect
Comment
The proposed standard is unsuitable because EPA has never defined
what constitutes "protection of public health." As a specific example,
EPA has not shown that pulmonary function and ventilatory pattern
changes are adverse health effects.
Agency Response
As stated in the Criteria Document, the pulmonary function
changes which have been observed in clinical exposures of healthy
subjects to ozone are reversible, and the available evidence does not
suggest that small changes in lung function (unaccompanied by discomfort
systems or impairment of oxygen uptake) would interfere with normal
activity in healthy individuals. However, even small changes in people
with underlying respiratory disease such as asthma, chronic bronchitis,
and emphysema can interfere with normal activity and thus may signal
impairment of public health.
Comment
EPA should identify where adverse effects begin in the
continuum of responses to pollutants.
Agency Response
In conducting a preliminary risk assessment, EPA interviewed
several biomedical experts to obtain their judgments as to the risk of
exceeding the threshold of adverse health effects in sensitive persons
for alternative standard levels. An essential feature of this risk
assessment procedure is the utilization of the experts' judgments
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26
as to the point in the continuum of physiological responses to ozone in
the ambient air which constitutes an adverse health effect. As an
example of this point, several experts indicated that a 0.5% decrease in
pulmonary function ( e.g., forced expiratory volume-1 second test)
would be inconsequential, whereas a 50% decrease would be a severe
effect in sensitive persons; the experts stated they would
begin to be concerned with a 5-15% decrease.
Comment
Sever a l_comrnents_ stated that quickly reversible ^irritation
experienced for a short period of time is a welfare effect
related to personal comfort and well-being and should therefore
be addressed under the secondary standard.
Agency Response
The Criteria Document states that physical discomfort, as
manifested by symptoms such as difficulty in breathing, chest tightness,
and pain on deep inspiration, has usually been observed in clinical
studies in conjunction with pulmonary function1 changes. Even when
reversible, respiratory symptoms may restrict normal activity or
limit the performance of tasks. In clinical studies, realistic
levels of ozone (0.3 ppm) have provided sufficient discomfort in healthy
subjects as to prevent completion of experimental protocols, particularly
when vigorous exercise was involved. Accordingly, the Criteria Document
concluded that increased rates of respiratory symptoms constitute
impairment of public health. On this topic, a physician from the California
Department of Health stated his medical opinion (Docket OAQPS-78-8,
IV-F-31) that symptoms such as tne above constitute adverse
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pulmonary function decrements and an increased pulmonary work load for
affected individuals. He expressed his concern for the long-term
effect of repeated exposure to levels of ozone sufficient to induce
such symptoms. EPA concurs in this view and considers such symptoms,
even though transitory, to be of concern in selecting the level of
the primary standard.
EPA's Interpretation of Cited Studies
Comments
1. DeLucia and Adams Study
(a) EPA has misread the DeLucia and Adams study in claiming
significant effects have been reported at 0.15 ppm
for 1 hour.
(b) Mouthpiece breathing may have invalidated the DeLucia
and Adams study.
(c) Since DeLucia and Adams demonstrated effects at 0.15 ppm
in healthy individuals, more susceptible populations would
be expected to sustain effects at lower levels.
Agency Responses
(a) EPA acknowledges that DeLucia and Adams failed to demonstrate
any statistically significant decrements in pulmonary function resulting
from exposure to 0.15 ppm for 1 hour. However, in groups as small as
those tested by DeLucia and Adams (six subjects), tests of statistical
significance are difficult to interpret. The Criteria Document con-
cluded that the study by DeLucia and Adams, although unreplicated,
has raised the question of whether Q+ concentrations as low as 0.15 ppm
exert effects in a portion of healthy subjects exercising vigorously.
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28
Indeed, DeLucia and Adams specifically state that the two most
sensitive subjects sustained markedly impaired respiratory function
and exercise ventilatory patterns during the two most stressful exercise
protocols in the four ozone-exposure experiments (i.e., both 0.15 ppm
and 0.30 ppm).
Furthermore, DeLucia and Adams state that most of the subjects
experienced subjective symptoms of discomfort (e.g., congestion,
chest pain, and cough) when exposed to 0.15 ppm for 1 hour under the
most stressful exercise protocol (equivalent to running about 6 miles
in an hour). DeLucia and Adams did not report the incidence of these
symptoms in a quantitative manner, but this fact does not remove EPA's
concern about the implications for healthy persons such as those tested
by DeLucia and Adams, or for more susceptible persons who may sustain
more severe reactions or who may be affected at lower concentrations
than those observed.
(b) As noted by the Criteria Document, persons tend to breathe
through their mouths when exercising. Thus, DeLucia and Adam's utilization
of mouthpieces to dispense 0- is probably representative of actual
exposures in persons who in the course of their nbrmardaily activities are
undergoing exercise.
(c) EPA agrees with this comment, as noted above. EPA considered
the implications of this study for more susceptible members of the
population in its determination of the margin of safety for the ozone
standard.
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Comments
2. Schoettlin and Landau Study
(a) There are still problems with the reliance on this study
due to ambiguities which remain in its interpretation, and because
more recent studies of effects of 03 on asthmatics have failed to
corroborate this study's conclusions.
(b) EPA's interpretation of the concentration at which
Schoettlin and Landau correlated increased incidence of asthmatic
attacks is unnecessarily conservative. There is good reason to believe
that the 0.25 ppm oxidant concentration cited by Schoettlin and Landau
was a daily peak (5-minute average) concentration rather than a daily
maximum hourly concentration, as EPA claims. Furthermore, the level of
ozone occurring on these high oxidant days would have been less than the
level of oxidant reported.
Agency Responses
(a) The Criteria Document recognizes that limitations exist
which render interpretation of the Schoettlin and Landau study difficult.
Nevertheless, Schoettlin and Landau concluded that the proportion of
asthmatics having attacks was significantly greater on days when the
oxidant concentration exceeded 0.25 ppm than on days when the concentration
was below that level. EPA does not believe that this conclusion has been
convincingly refuted by more recent studies. The reported results of the
recent epidemiological study by Kurata et al.. although inconclusive,
are qualitatively similar to those of Schoettlin and Landau. EPA's
analysis (Docket OAQPS 78-8 , ) of the findings presented in the Kurata
study indicates that a statistically significant elevation of the asthma
index occurred on days when the maximum instantaneous (5-minute average)
ozone concentrations exceeded 0.28 ppm.
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30
(b) EPA acknowledges that it is uncertain from Schoettlin and
Landau's paper what averaging time was used in correlating oxidant con-
centration and incidence of asthma attacks. However, as stated in the
Criteria Document, consultations with the authors have established
that daily asthma attack rates were correlated with daily maximum
hourly average oxidant levels. EPA considers that these consultations
have satisfactorily resolved the controversy regarding the averaging
times used by Schoettlin and Landau.
Furthermore there is concern that ozone levels were lower than
the oxidant readings with which Schoettlin and Landau correlated
asthma attack incidence. Ozone levels have been shown to range from
approximately 65 percent to nearly 100 percent of the total oxidant
levels. For this reason, EPA is concerned that ozone in the ambient
air at daily maximum hourly average concentrations less than 0.25 ppm
may adversely affect asthmatic persons.
3. Hammer et al: (Student Nurse Study)
Comments
(a) Methodological problems with this study diminish its use-
fulness.
(b) It is uncertain that oxidants caused the increase in symptoms
observed in this study.
Agency Responses
(a) As noted in the Criteria Document, the results of this
epidemiological study closely correlate with the results of clinical
studies. This fact, along with the extensive data base evaluated
(about 53,000 person-days of observation}, enhances the reliability
of Hammer's study.
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31
(b) Hammer et al. found that symptom frequencies were more
closely correlated to photochemical oxidants than to several other
environmental parameters.(e.g., carbon monoxide and nitrogen dioxide).
In addition, the Criteria Document noted that the oxidant levels at which
cough and chest discomfort were observed to increase in the student
nurse population were quite similar to ozone concentrations which
have been observed to produce impairment of pulmonary function and
respiratory irritation in experimental exposures of healthy
subjects performing intermittent light exercise (0.37 ppm for 2 hours).
Consequently, it is reasonable to propose that photochemical oxidants —
and specifically ozone in the ambient air -- contributed substantially to
observed increases in rates of cough, chest discomfort, and headache.
4. Hazucha Clinical Study
Comment
Results reported by-Hazucha on impairment of pulmonary function
at ozone levels of 0.25 ppm for 2 hours are not statistically significant,
Agency Response
The small number of subjects (3) examined at that exposure
precludes the application of statistical methods to the results. The
absolute value of the pulmonary function decrements (about 5 percent)
is the more relevant factor in evaluating this study's results.
As described in the Criteria Document, the small pulmonary function
changes observed by Hazucha in a 2-hour exposure of healthy subjects
undergoing intermittent light exercise lies along a continuum of
responses when compared with results at higher concentrations and similar
exposure regimes. There is no indication that 0.25 ppm is the threshold
for that exercise level, and indeed DeLucia and Adams have shown sympto-
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32
matic effects in healthy individuals that are indicative of pulmonary
function impairment at levels as low as 0.15 ppm.
5. Studies in which effects were not observed at levels above 0.15 ppm
Comments
(a) The National Academy of Sciences (NAS) document, Ozone and Other
Photochemical Oxidants, was cited in several comments as concluding that ef-
fects in humans have been observed only from ozone exposures above 0.25 ppm.
(b) Linn et al. found no adverse effects on asthmatics exposed
to 0.20 - 0.25 ppm for 2 hours under conditions of heat and exercise.
(c) Hackney et al. observed human health effects only at ex-
posures above 0.25 ppm for 2 hours.
Agency Responses
(a) The NAS document states that "some limited studies show
evidence of human health effects of exposure to pure ozone at concen-
trations as low as 0.25 ppm . . ." This document was prepared before
the publication of the DeLucia and Adams and von Nieding et al. studies
which suggest effects at lower levels. Furthermore, this NAS document
in no way concludes that effects due to ozone, as it occurs in the ambient
photochemical mix, do not occur at concentrations below 0.25 ppm.
(b) While it is true that Linn et al. found no statistically sig-
nificant impact on pulmonary function in their study, there was a slight
increase in symptom scores during ozone exposure, and these investigators
did find statistically significant changes in blood biochemical factors.
While the clinical significance of these latter changes is uncertain, they do
represent alterations in normal body functions and cannot be discarded in
selecting a standard that protects public health with an adequate margin
of safety.
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(c) Although the Criteria Document states that Hackney et al.
found no lung function changes of note at 0.25 ppm for 2 hours even
among "reactive" subjects (persons giving a history of cough, chest
discomfort, or wheezing in response to allergy or air pollution
exposure), this finding does not invalidate or permit EPA to ignore
other studies which report effects at 0.25 ppm or below.
6. Other Human Studies
Comments
(a) Von Nieding has demonstrated effects on pulmonary function of
healthy individuals at 0.10 ppm ozone.
(b) EPA cannot justify a conclusion that Japanese epidemiological
studies indicate a risk of symptomatic effects in humans from ozone
exposures below 0.15 ppm for 1 hour.
Agency Responses
(a) EPA is concerned about the findings of von Nieding et al.
showing decreased oxygen pressure in arterialized blood and increased airway
resistance after 2 hours of exposure to 0.10 ppm ozone and intermittent
light exercise. However, the Criteria Document points out several limita-
tions of von Nieding's studies, most notably the use of non-standard
physiologic measurement methods. Thus, although von Nieding's findings
cannot be ignored in the standard-setting process, they are not conclusive,
and must be interpreted cautiously.
(b) Makino and Mizoguchi reported an epidemiological study of
Tokyo students that showed increased rates of discomfort symptoms
on days when the oxidant level (believed to be a daily maximum hourly
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34
average concentration) exceeded 0.15 ppm as compared with days when it
fell below 0.10 ppm. Althounh the Criteria Document cautions that these
studies may not be applicable to ambient situations in the U.S., EPA
nonetheless must set a standard which considers uncertainties which medical
research has not yet resolved and must consider evidence such as the
Japanese studies in selecting an adequate margin of safety.
7. Validity of Clinical Studies in General
Comment
Testimony heard on August 22, 1977 at the Dallas public hearing
alleged that ozone generators used in clinical health studies were
producing other toxic materials in addition to ozone. It was further
alleged that these additional oxidants were present in large quantities
(as high as 300 percent greater than ozone) and that adverse effects
noted in clinical studies were probably a result of the additional
oxidants and not ozone.
Agency Response
EPA has concluded that the experimental evidence offered to support
these findings is unconvincing and cannot be substantiated. The issue of
additional oxidants in the output of ozone generators is not a new issue
and was addressed in the 1977 National Academy of Sciences document on ozone.
This document focuses on three such oxidants, singlet oxygen and two forms
of atomic oxygen. Although singlet oxygen is described as the most stable
of these materials, the National Academy of Sciences document concludes that
even sinqlet oxygen is too unstable for any more than a minute fraction of
the amount generated to be present at more than 0.1 seconds downstream
from the generator output. Evidence submitted to EPA at the hearing indicates
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35
that the sampling lines used in some of the experiments would require a
residence time of 20 seconds, far longer than the estimated survival
time for the additionally-produced oxidants. Because of this, and
because new non-validated measurement techniques were used, EPA feels
that the higher numbers reported can probably be attributed to the reagent
used in the detection device and not to the actual presence of any additional
oxidant. EPA has provided a more extensive discussion of this issue in
the docket as well as the results of laboratory work conducted to support
this conclusion.
Margin of Safety
Comment
EPA has proposed a standard with an inappropriate margin of safety.
The margin of safety was criticized as being either inadequate or too great.
Agency Response
The Clean Air Act requires that EPA set a standard that allows an
adequate margin of safety requisite to protect the public health. As
stated in the support material to the Clean Air Act, the standard must
protect against hazards which research has not yet identified. EPA feels
this is a judgment which must be made by the Administrator after weighing
all the medical evidence bearing on ozone. This includes inconclusive
evidence as well as findings from studies which are considered definitive
and not subject to challenge. Factors which must be considered by the
Administrator in selecting an adequate margin of safety include: (1)
findings from animal studies which show increased mortality and other serious
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36
effects at relatively low ozone levels, (2) concern that health studies
may not always reflect the health impact in more sensitive segments of
the population, and (3) concern that ozone may produce an enhanced effect
when combined with other elements of the photochemical mix commonly present
in the urban atmosphere but not present in clinical study chambers.
Use of Animal Studies
Comment
EPA has failed to give appropriate consideration to the results of
animal studies, especially those involving young animals and those
examining reduced resistance to infection.
Agency Response
EPA is concerned about the studies which have demonstrated enhanced
effects in young animals and decreased resistance to infection. The in-
fection effect has been demonstrated at exposures as low as 0.08 ppm for
3 hours. The Criteria Document concluded that these findings have
definite human health implications, although different exposure levels
may be associated with such effects in humans. For this reason, these
results cannot be the sole factor used in selecting the level of the
primary standard. However, as is the case with other inconclusive evidence,
EPA must consider these studies in selecting an adequate margin of safety.
Comment
There is no evidence of reduced resistance to infection in epidemiologic
studies in places such as Los Angeles.
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37
Agency Response
Epidemiological studies have been inconclusive in demonstrating
this effect in man. However, EPA does not agree with this comment.
Durham's study of air pollution effects on college students, although
inconclusive, suggests that rates of new illness increase during short-term
exposures to elevated oxidant concentrations. Also, several studies documenting
increased levels of mucous membrane irritation during periods of ozone ex-
posure suggest indirectly that susceptibility to infection may rise during
these periods. While animal study findings cannot be directly extrapolated
to man, the criteria document concludes that the reactions observed in mice
represent effects on basic biological responses to infectious agents, and
there is no reason to believe that the pollutant-induced alterations of
basic defense mechanisms that occur in mice could not occur in humans. Thus,
these studies cannot be ignored in the standard-setting process.
Exposure of Sensitive Groups
Comment
EPA is being unnecessarily stringent in selecting the sensitive
population. The standard could be much less stringent without endangering
the health of such persons if EPA accounted for the portion of time that
persons are indoors and thus not exposed to higher ambient concentrations.
Agency Response
The legislative history of the Clean Air Act makes quite clear
Congress1 intention to protect sensitive persons (asthmatics and emphysematous
patients are cited as examples) who in the normal course of daily activity
are exposed to the ambient environment. Air quality standards are to be
established with reference to protecting the health of a representative sample
of persons comprising the sensitive group rather than a single person in such
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38
a group. Standards must be based on a judgment of a safe air quality level
and not on an estimate of how many persons will intersect given concentration
levels. EPA interprets the Clean Air Act as providing citizens the oppor-
tunity to pursue their normal activities in a healthy environment.
Synergistic Effects and Chemical Species of Standard
Comment
There were objections to the proposed change of the chemical designa-
tion of the standard from photochemical oxidants to ozone because the
health impacts of photochemical air pollution arise not only from ozone,
but also from the spectrum of other gaseous and parti oil ate pollutants which
co-exist with ozone. There was also concern that the change in the chemical
designation signalled a change in emphasis in oxidant control efforts which
would impede progress in the reduction of non-ozone components of the
photochemical oxidant mixture such as peroxyacetylnitrate (PAN). Specific
concern was expressed regarding the eye-irritating components of the mixture,
since at ambient levels ozone alone is not an eye irritant.
Agency Response
Studies (such as Hazucha and Bates) have demonstrated the potential
for greater health impacts resulting from exposure to ozone in combination
with other pollutants in the ambient air than for ozone alone. The ozone
standard is not intended merely to protect against the levels of ozone
which have been demonstrated to produce effects in clinical studips ex-
posing subjects to highly purified air to which ozone has been added.
Rather, the standard is set to protect against ozone as it occurs
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39
in the ambient air, in combination with other pollutants. Such considera-
tions are involved in determining an adequate margin of safety.
One reason for changing the chemical designation of the standard from
photochemical oxidants to ozone is to correct an inconsistency between the
title of the standard (photochemical oxidants) and the chemical species (ozone)
which has always been measured to determine compliance with the Standard. Con-
sequently, no redirection of control efforts is comtemplated; i.e. reductions in
hydrocarbon and nitrogen oxide emissions will continue to be required in order
to reduce the levels of the secondarily generated pollutant (ozone) measured
to determine compliance with the standard.
Furthermore, with regard to the issue of whether or not measures taken to
reduce ozone will also reduce other manifestations of photochemical pollution
such as eye irritation, the criteria document describes the evidence from
laboratory and theoretical studies as indicating that for urban
atmospheres, reductions in hydrocarbon and nitrogen oxide emissions should
have even greater impacts on ambient PAN than on ambient ozone. Similarly,
laboratory data suggest a linear relation between hydrocarbon emissions and
ambient levels of photochemically produced aldehydes. Since PAN and such
aldehydes as formaldehyde and acrolein are known to be eye irritants, the
criteria document concludes that emission control measures for ozone reduction
will probably have a positive effect on reducing eye irritation in those
situations where eye irritation is associated with photochemical processes
(6.9., Los Angeles).
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40
Risk Assessment Method
Comment
The risk assessment method should not be used at this time because
it has not been reviewed adequately by the Science Advisory Board or
the scientific community.
Agency Response
The risk assessment method is not being used to set the ozone stand-
ard. However, in determining what ozone standard has an adequate margin
of safety, the findings of the initial application of the risk assessment
method to ozone have been- considered. EPA agrees that the method has
not received sufficient review. The method will be published in the
open literature and the Science Advisory Board is forming an ad-hoc
subcommittee to review the method.
Comment
EPA's risk assessment method is incomplete.
Agency Response
EPA agrees with the comment. As applied to ozone, the risk assessment
method assesses the risk (probability) that ozone would contribute to
heal'th effects in some sensitive people if alternative standards were just
met. A complete risk picture would also include information on:
(a) a best (point) estimate of the number of peop-le affected;
(a1) the "expected number" (in a statistical sense) of people
affected;
(a") various risks (probabilities) that the actual number of people
affected would be various amounts greater than the expected
number;
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41
(b) a best (point) estimate of the amount of health damage;
(b1) the "expected" health damage; and
(b") various risks (probabilities) that the actual health
damage would be various amounts greater than the expected
health damage.
As is noted in the draft EPA document explaining the risk assessment
method, there are complex technical problems which must be dealt with
in developing responsible information of this type suitable for use in
setting National Ambient Air Quality Standards. EPA is presently develop-
ing the capability to generate this type of information and will only
consider its risk assessment method complete when it includes this
capability.
Comment
The main problem with the risk assessment method stems from its
purpose. Instead of estimating health damage, EPA provides a table of
risk numbers without providing an estimate of their health significance;
these numbers serve no function.
Agency Response
EPA agrees that the risk estimates provided do not serve the function
of estimating health damage, but we do not agree that the estimates are
without value. The function of these estimates is to indicate the vary-
ing risk (or probability) that some sensitive people would suffer health
effects in a given period of time if alternative ozone standards were
just met. For each health effect category the response which is of
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42
sufficient concern to be deemed a health effect has been decided and
its seriousness described. Under EPA's interpretation of the intent
of the Clean Air Act this is an important function to be served by a
risk assessment that is to be used in setting National Ambient Air
Quality Standards.
There were many comments on procedural and technical aspects of the
risk assessment method. EPA will address these comments in the detailed
responses to be placed in the docket. Some of the comments point out
improvements that can be made in the risk assessment, method, while others
reflect misunderstandings that will be addressed in the detailed docket
responses. Some of the comments provide discussion and opinions on
various complex issues that arise in the subject areas of risk assessment
and standard setting methodology. EPA will take these comments into
advisement as it develops its risk assessment and standard-setting
'methodologies.
Secondary Standard
Comment
EPA's proposal to retain the existing secondary standard is based
entirely on evidence of possible damage to extremely sensitive vegetation.
An adequate economic analysis which considers the incremental costs
and benefits of alternative secondary standard levels should be conducted.
EPA should then weigh the economic costs of pollution control measures
against the benefits of reduced damages from lower ozone concentration
levels before setting a secondary standard.
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43
Agency Response
The Clean Air Act requires EPA to set a national secondary ambient
air quality standard at a level which in the judgment of the Administrator
is "requisite to protect the public welfare from any known or anticipated
adverse effects." The term "public welfare" is defined in Section 302(h)
of the Clean Air Act and includes among other things effects on crops,
vegetation, wildlife, visibility, and climate, "as well as effects on economic
values and on personal comfort and well being."
EPA agrees that both the incremental control costs and the benefits/
damages associated with alternative standard levels need to be carefully
considered in selecting the level of the national secondary ambient air
quality standard. However, it should be kept in mind that there are large
uncertainties associated with both the estimation of control costs and
benefits/damages associated with alternative standard levels. For example,
the current state of knowledge and data base for making reasonably accurate
quantitative estimates of the economic loss due to ozone-related plant
damage are extremely limited and inadequate. EPA has conducted a limited
economic analysis, employing the best data currently available, to obtain
a rough picture of the maximum benefits to be achieved by a secondary stand-
ard more stringent than the primary.. "(A copy of "the" staff report, entitled
"Estimate of Economic Benefits Associated with Alternative Secondary Ozone
Standards" has been placed in the docket.) In concluding that a secondary
standard more stringent than the primary is not justified at this time, EPA
has considered the above mentioned analysis, discussions with expert plant
pathologists, the-data in the criteria document on damages to plants and
materials, and the incremental control costs.
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44
Implementation and Attainability
Comments were received regarding the effectiveness of hydrocarbon
controls in reducing levels of ozone in the ambient air as well as on
the issue of whether or not the statutory deadline for submission of
revised State implementation plans (SIP) for non-attainment areas should
be postponed due to the changes in the photochemical oxidants standard.
The Agency responses to these comments are contained in the accompanying
Federal Register notice for the revision of the CFR Part 51 regulations
pertaining to the implementation of the standard.
Comment
Cost of control should be considered in selecting the level of the
primary standard.
Agency Response
The Agency's position regarding this point was addressed in the preamble
to the proposed regulation (43 FR 26963); this position remains
unchanged. The Clean Air Act specifies that National Ambient Air
Quality Standards are to be based on scientific criteria relating to
the level that should be attained to adequately protect public health
and welfare. Considerations of cost of achieving those standards or the
existence of technology to bring about needed reductions of emissions are not
germane to such a determination, as the words of the Act and its legislative
history clearly indicate. However, EPA has conducted an analysis of the
cost and economic impacts of the control programs required to attain alterna-
tive ozone standard levels in order that the public may be better informed
of the consequences of the Agency's decision. This analysis and the
comments received in response to it are available to the States for
their use in developing strategies to implement the standard.
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45
Comment
The cost estimates in EPA's cost and economic impact assessment
underestimate the actual costs incurred by specific industries.
Agency Response
EPA has carefully reviewed and considered these comments and is pub-
lishing a revised economic impact assessment which is available from
Mr. Padgett at the previously mentioned address.
Comments on Natural Background Concentrations
Several comments were made regarding the issue of natural source con-
tribution to ambient ozone concentrations. These comments relate primarily
to the extent that natural background was considered in developing the
proposed standards and the attainability of these standards, considering
that natural background may at times contravene the proposed levels.
Some of the comments suggested that EPA ignored or did not adequately con-
sider natural background in developing the proposed standards and
related control programs. While not emphasized in the preamble to the
proposed rulemaking, EPA was and is cognizant of the background levels
that can be attributed to natural sources. This topic was treated ex-
tensively in the Revised Criteria Document. Furthermore, EPA procedures
for preparation of control plans recommend allowance for natural background
in developing control strategies for ozone.
For several years, EPA has had an active field and laboratory re-
search program seeking to determine the nature and extent of background
concentrations of ozone. The results of these studies have been widely
publicized in EPA reports, scientific literature, and public conferences.
One comment indicated that EPA had ignored evidence of natural source
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46
impacts reported in contract work done for the Agency and that this
information had not been released for public review. Actually, all
pertinent information available to EPA were considered. However, there
may have been some contractually developed information that had not been
released or could not be specifically cited because the contract studies
were still in progress and the resulting data had not been fully validated
or analyzed. Subsequent to the comment, all information in question were
released publically or arrangements have been made to release them as soon
as possible.
EPA's review of data indicative of natural background contribution
leads the Agency to conclude that such levels are usually well below the
proposed levels of the standard, especially during the season when the
most active production of photochemical ozone occurs. However, it is
possible that natural events could occasionally contravene the proposed
standard levels. EPA policy (see 40 CFR 51.15(d)) permits data for such
occurrences to be disregarded for regulatory purposes. Such events are
usually distinguishable because they tend not to coincide with conditions
conducive to buildup of man-caused, photochemically produced ozone. Field
measurements at some remote sites where man-caused ozone is likely to be
negligible have shown low, but not insignificant, rates of exceedances of
the 0.08 ppm level originally proposed for the secondary standard. The
frequencies decrease markedly for concentrations above 0.10 ppm, such that
the occurrence of natural exceedances can be considered relatively rare
at any particular location.
One comment indicated that stratospheric tracer levels measured at
surface sites increase by about 40 percent between the front and back
side of high pressure systems in the Eastern United States, thus suggesting
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47
that stratospheric ozone, through subsidence and horizontal circulation
In highs, plays a significant role in the widespread buildup of ozone
that tends to occur in the back side of highs in the East during the
photochemically active season. EPA's estimate is that, even if
commonly occurring natural ozone background were increased by 40 percent,
it would be insufficient to exceed proposed standard levels. Also, a
corresponding increase between the tracer and ozone of stratospheric
origin would not be expected, since the tracer is chemically stable near the
surface, while ozone is rapidly depleted by reactions with surfaces and air
contaminants.
Some comments referred- to possibly significant contribution to ozone
concentrations from reactions involving organic compounds emitted by
vegetation. Such emissions are abundant, relative to man-made emissions,
but are relatively diffuse spatially. A recent statistical study was cited
in some of the comments which reported a high correlation between
vegetative growth in the Bay Area of California, as indicaleu u> winter
rainfall, and the frequency of days with concentrations above the
0.08 ppm level. EPA, however, has not seen sufficient physical
evidence of a relative abundance of natural organics or associated
ozone increases in ambient air to consider vegetative sources as
significant contributors to high ambient ozone levels. The principal
source of natural ozone is still considered to be the stratosphere, with
gradual transfer accounting for the more commonly observed background
levels, and sporadic intrusions being the principal cause of anomalous high
values.
Although research will continue to definitively assess natural source
contribution, EPA feels that adequate consideration has been given this
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48
issue in developing the ozone standards and control programs. Furthermore,
it is EPA's judgment that natural background levels will not prevent
attainment of the standards.
Procedural Issues
Comment
EPA's use of an "Advisory Panel on Health Effects of Photochemical
Oxidants" was procedurally incorrect in that certain legal requirements
on establishment and use of Advisory Committees were not followed.
Agency Response
The Advisory Panel consisted of a group of medical experts retained
by EPA as consultants for the purpose of obtaining their interpretation of the
evidence presented in a preliminary version of the criteria document.
Consequently, EPA considers that the Panel was not subject to the requirements
of the Advisory Committee Act of 1972. In any case, all the objectives
of that Act have been met, since the Panel's report has been in the docket
and subject to comment since proposal. All viewpoints on the health effects
of ozone have been presented to EPA and have been given consideration equal
to that given the Panel's report.
Comment
EPA has failed to comply with the recommendations of the statutory
scientific review body, the Science Advisory Board (SAB), in revising
its criteria document, as evidenced by the SAB's refusal to approve the
criteria document.
Agency Response
EPA has responded to each of the substantial comments made by the SAB
subcommittee established to review the criteria document; these responses
have been placed in the docket and are available for public review. Follow-
ing the last meeting of the subcommittee in February 1978, EPA personnel
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49
consulted with the members of the subcommittee individually to resolve
the objections expressed at that meeting. In a subsequent correspondence
with EPA, the subcommittee's chairman, Dr. James L. Whittenberger, stated
that "any remaining complaints I have are minor." (Docket OAQPS 78-8,
H-A-E-2-27).
Comment
EPA has failed to submit the proposed standard to the SAB for
review as required by the Environmental Research, Development, and
Demonstration Authorization Act of 1978 (P.L. 95-155). EPA should do
so before promulgating the standard.
Agency Response
EPA has not proceeded as requested by this comment. P.L. 95-155
states that the SAB may comment on the technical and scientific basis
of an EPA proposal. The SAB has already extensively reviewed the
criteria document and has given its advice on the technical and scientific
basis for the document. Since this document is the principal basis for the
proposed standard, resubmittal to the SAB is not necessary to effectuate
P.L. 95-155.
SELECTING THE LEVEL OF THE PRIMARY STANDARD
EPA's objective in setting the standard level is to select an ozone
concentration that will reflect an accurate consideration of the existing medi-
cal evidence and an adequate assessment of the uncertainties in this evidence,
and thus will protect all population groups with an adequate margin of safety.
Relevant to this charge, the National Academy of Sciences reached the
following conclusion in 1974:
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... in no case is there evidence that the threshold levels
have clear.physiological meaning, in the sense that there are
genuine adverse health effects at and above some level of
pollution, but no effects at all below that level. On the
contrary, evidence indicates that the amount of health damage
varies with the upward" and downward variations in the concen-
tration of the pollutant, with no sharp lower limit.
The House of Representatives Committee on Interstate and. Foreign
Commerce has observed that the concepts of threshold and adequate margin
of safety that underlie the language of Section 109(b)(l) of the Clean
Air Act are necessary simplifications to permit the Administrator to
set standards.
The criteria document confirms that no clear threshold can be identified
for health effects due to ozone. Rather, there is a continuum consisting
of ozone levels at which health effects are certain, through levels at
which scientists can generally agree that health effects have been
clearly demonstrated, and down to levels at which the indications of
health effects are less certain and harder to identify. Selecting a
standard from this continuum is a judgment of prudent public health
practice, and does not imply some discrete or fixed margin of safety that
is appended to a known "threshold."
The uncertainties with which such a judgment must deal are the
result of several factors. First, human susceptibility to health effects
varies and we cannot be certain that experimental evidence has accounted
for the full range of susceptibility. Second, we cannot be certain that
all effects occurring at low ozone levels have been identified and demon-
strated. Third, variations in weather create uncertainty as to the expected
annual maximum ozone concentrations.
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The Clean Air Act, as the Administrator interprets it, does not permit
him to take factors such as cost or attainability into account in setting
the standard; it is to be a standard which will adequately protect public
health. The Administrator recognizes that controlling ozone to very low
levels is a task that will have significant impact on economic and social
activity. This recognition causes the Administrator to reject as an
option, setting a zero-level standard as an expedient way of protecting
public health without having to decide among uncertainties. However, it is
public health, and not economic impact, that must drive the decision. Thus,
the decision as to what standard protects public health with an adequate
margin of safety is based on the uncertainty that any given level is low
enough to prevent health effects, and on the relative acceptability of various
degrees of uncertainty, given the seriousness of the effects.
In selecting the proper level for the standard, EPA must make
assessments and judgments in five critical areas:
1. Reported effect levels from human studies.
2. Characterizing the sensitive population.
3. Nature and severity of effects.
4. Probable effect level in sensitive persons.
5. Judgment of a standard level below the probable effect level
that provides an adequate margin of safety and an acceptable
level of risk.
REPORTED EFFECT LEVELS
In the preamble to the proposed standard (43 FR 26965), EPA presented
a table of demonstrated effect levels in man ranging from 0.15 to 0.30.
Based on suggestions received during the comment period, that table has been
expanded to include a greater number of studies where effects have been
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REPORTED EFFECT LEVELS
Concentration,
pptn
0.01 -
0.30
0.03 -
0.30
0.10
0.10 -
0.15
0.15
0.20
0.20 -
0.25
0.25
0.25
0.25
0.25
0.28
0.30
0.30*
0.37
0.37
0.37
0.37
0.37
Exposure Duration,
hours (for clinical
studies); Averaging
tine (for epidera to-
logical studies)
binourly
average
hourly
average
Z
probably dally
maximum hourly
average
1
3
2
Z
2 and 4
dally maximum
hourly average
0.5 - 1
daily maximum
instantaneous
(5-minute)
average
1
dally maximum
hourly average
Z
2
2
2
Z
Pollutant
Measured
(0, = ozone,
0- » oxidant)
°3
°x
°3
°x
°3
°3
°3
°3
°3
°x
°3
°3
°3
°x
°3
S§3
°3
S°Z
Reported
Effect (s)
Lung function parameters in about Z5X of Japanese
school children tested were significantly corre-
lated with 0, concentrations (over the range of
0.01 - 0.30) In the 2 hours prior to testing.
Although significant correlation was observed be-
tween decreased athletic performance & 0 concen-
trations 1n the range of 0.03 - 0.30 ppm, the
Criteria Document concludes that no consistent
linear relationship could be detected below
about 0.10 pptn.
Decreased 0. pressure in arterial 1zed blood.
Increased airway resistance observed using non-
standard measurement techniques.
Increased rates of respiratory symptoms and head-
ache were reported by Japanese students an days when
0 concentrations exceeded 0.15 ppm as compared to
days when 0 concentrations were less than 0.10 ppm.
Subjective symptoms of discomfort were observed by
most subjects, and discernible but not statistical-
ly significant changes in respiratory pattern oc-
curred while performing vigorous exercise.
Reduction in visual acuity (night vision) ob-
served .
Asthmatic patients exposed under intermittent
light exercise conditions showed no statistically
significant changes In respiratory function.
Symptom scores Increased slightly during Oj ex-
posures. . Small but statistically significant Y
blood biochemical changes occurred.
Small changes in lung function were observed in 3
subjects performing intermittent light exercise.
No lung function changes of note were observed in
"reactive" subjects (who had histories of cough,
chest discomfort or wheezing associated with air
pollution or allergy) while performing inter-
mittent, light exercise.
The average number of asthma patients having
attacks was statistically significantly elevated
on days when Ox levels exceeded 0.25 ppm.
Blood samples of exposed subjects had increased
rates of sphering of red blood cells
Although the reported results are inconclusive, "
EPA's examination of the evidence presented
suggests exacerbation of asthma when 0, levels
are above 0.28 ppm.
Subjective symptoms of discomfort and statistical-
ly significant changes in pulmonary function were
observed In subjects undergoing vigorous exercise.
Increased rates of cough, chest discomfort, and
headache were observed in student nurses on days
when the Ox concentrations exceeded 0.30 ppm.
Discomfort symptoms & significant changes In lung
function were observed in subjects undergoing
Intermittent light exercise.
Exposure to 0, and SO, together produced changes
In lung function substantially greater than the
sum of the separate effects of the Individual
pollutants.
The observed 0, - SO. interactive effect on lung
function was considerably smaller than that seen
by Hazucha and Bates. The authors concluded that
the earlier study probably more nearly simulated
a smog episode in regions having high oxidant and
sulfur oollution.
Reference(s)
Kagawa and Toyama
(1975); Kagawa, et al.
(1976)
Wayne, et al.
(1967)
von Nieding, et al.
(1976)
Makino and Mlzoguchi
(1975)
OeLucia & Adams
(1977)
Lagerwerff
(1963)
Linn, et al.
(1978)
Hazucha (1973)
Hackney, et al.
(1975)
Schoettlin and
Landau (1961)
Brinkman. et al.
(1964)
Kurata, et al.
(1976)
OeLucia and Adams
(1977)
Hammer, et al.
(1974)
Hazucha, et al. (1973),
Folinsbee7"eT"al. (1975);
Silverman, eTlT. (1976)
Hazucha and Sates (1975)
Bell, et al. (1977)
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53
reported. EPA feels this is a more complete representation of the
medical evidence since it includes some less conclusive studies at low levels
which cannot be discarded in weighing the full body of health data.
This table is not intended to provide, nor can it provide, an un-
disputed value for the adverse effect level in sensitive individuals.
It does indicate however that disruption or modification of normal
body functions most likely occurs at relatively low ozone concentrations.
The reported findings leave open the question of increased intensity of
effects in more sensitive persons and the concern that effects reported
in some studies may occur at lower concentrations when ozone is in combina-
tion with other urban pollutants.
SENSITIVE POPULATION
The legislative history of the Clean Air Act indicates that in setting
primary ambient air quality standards, EPA is to direct its efforts at groups
of "particularly sensitive citizens such as bronchial asthmatics and
emphysematics who in the normal course of daily activity are exposed to the
ambient environment." (S. Rep. No. 91-1196, 91st Cong. 2d Sess. 10 (1970).)
Clinical and epidemiological studies have shown that persons with chronic
obstructive airway disease, particularly asthmatics,, appear most sensitive
to changes in ozone concentrations. This is because their airways are hyper-
reactive to irritants such as ozone. These people are thus judged to be the
principal sensitive group of concern in setting the standard.
Studies have also established that exercise effectively increases
the ozone dose delivered to the target tissues in the respiratory tract.
Thus, persons engaging in exercise are particularly vulnerable to the
acutely irritating effects of ozone. However, the response of these
groups to such changes in concentrations has not been systematically studied.
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54
NATURE AND SEVERITY OF EFFECTS
Impaired Pulmonary Function and Clinical Symptoms — Ozone is a broncho-
pulmonary irritant which affects the mucous lining, other lung tissue
and respiratory function. Changes in lung function appear as increased
airway resistance, and reductions in vital capacity, expiratory flow rates
and diffusion capacity. These effects are greater in exercising individuals
and individuals with hyper-reactive airways (history of developing
symptoms during light activity in smog or history of asthma). Changes
in lung function are accompanied by clinical symptoms such as coughing,
chest tightness, and lower chest soreness.
Because the human respiratory system is endowed with a large reserve,.
even airway resistance increases of 50 to 100 percent will not ordinarily
be perceived in normal individuals. However, as stated in the criteria
document, "three considerations suggest that oxidant-associated changes
in lung function may signal impairment of public health. First, in
people with underlying respiratory illness such as asthma, chronic
bronchitis, and emphysema, even small decrements in lung function often
interfere with normal activity. Second, at experimental ozone concen-
trations as low as 0.30 ppm, decrements in lung function have usually
been accompanied by physical discomfort, as manifested in symptoms such
as sore throat, chest pain, cough, and headache. At times this dis-
comfort has been great enough to prevent the completion of experimental
protocols, particularly when subjects have been exercising vigorously.
It appears quite likely that the pulmonary irritant properties of ozone
(and perhaps other oxidants) underlie both the discomfort and the decre-
ments in function. Thus, at least when associated with ozone exposure,
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55
changes in lung function often represent a level of discomfort which,
even among healthy people, may restrict normal activity or impair the
performance of tasks."
Decreased Resistance to Infection — This effect is represented by an
increased rate of mortality in laboratory animals subjected to both a
bacterial challenge and exposures to ozone. According to some, studies,
the effect may be enhanced by the addition of such stresses as heat,
exercise, or the addition of other pollutants in combination with the
ozone dose. Despite the lack of confirmatory studies in man, and the
uncertainties involved in predicting human effects from animal studies,
most medical experts agree that decreased resistance to infection may
well occur in man and the lack of_such evidence is probably due
to the difficulty of detecting these responses in epidemiologic studies.
Aggravation of Chronic Respiratory Disease — It is generally accepted by
the scientific community that there is a link between ambient oxidant
levels and aggravation of pulmonary disease. This link was demonstrated
by the Schoettlin and Landau study which related the frequency of asthma
attacks to measured ambient photochemical oxidant concentrations. Several
studies have investigated the aggravation of emphysema and chronic
bronchitis without revealing any definitive links to photochemical oxidant
concentrations.
Air pollution is one of the many stresses which can precipitate
an asthma attack or worsen the disease state in persons with chronic
cardiopulmonary disease. Other factors which can act like ozone in
precipitating attacks include: respiratory infections, passage of cold
fronts, seasonal pollens, extreme heat or cold, and!emotional
disturbances.
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Eye Irritation — Eye irritation is associated with selected chemical
species (such as PAN) in the photochemical oxidant mix and other organic
vapors. There is no evidence that eye irritation is produced by
ozone. Since EPA is redesignating the standard from photochemical
oxidants to ozone, the eye irritation effect is not a critical one in
establishing the standard level.
Biochemical Effects ~ Experimental exposures of human subjects to ozone
have produced changes in blood biochemistry, such as increased fragility
of red blood cells and altered enzyme activities in the serum. The
significance of these ozone-mediated changes is not yet known,; and
changes of the magnitude observed in experimental exposures have not
yet been linked to any clinical diseases.
Carcinogenic, Mutagenic and Related Effects — Studies have been conducted
in an attempt to relate ozone to carcinogenic, mutagenic, and related
effects. Available evidence in these areas is not particularly helpful
in setting ambient ozone standards because most of the studies are as yet
unreplicated, and because some effects observed in lower life forms are
of questionable significance to man. The criteria document states that
the significance of effects such, as chromosomal aberrations has hot been
established. EPAis Science Advisory Board has recommended that certain
studies, which have not been replicated, should not be emphasized in the
criteria document.
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57
PRIMARY STANDARD
As illustrated in the table of reported effect levels, there is no
sharp break or threshold air concentration of ozone indicated by the data
as the onset of health effects. It is EPA's best judgment that responses
which may or may not be adverse probably occur in sensitive persons at levels
approaching natural background. At what point these responses become an
adverse health effect and at what level they most likely occur in sensitive
persons must necessarily be an informed judgment. EPA made such a judgment
in the proposed revision to this standard and has received no convincing
evidence that would change that choice. As stated in the proposal, this
judgment is based on: (1) our understanding of the medical evidence presented
in the criteria document and the effect level table, (2) the findings of the
advisory panel on health effects, and (3) the judgment of medical experts
- i
as to the adverse effect level in sensitive persons.] The health experts
who were consulted were asked to focus not only on the most sensitive
population group, but also on a very sensitive portion of that group
(specifically, those persons who are more sensitive than 99 percent of the
sensitive group, but less sensitive than 1 percent of that group). The
lowest effect level estimate cited by the health panel and the median
values generated through the expert interview process are reasonably
consistent, ranging from 0.15 to 0.18 ppm. (See table below.) Based on
this data and on the effect levels cited in the criteria document (0.15 -
0.30 ppm) 1t is EpVs judgment that the most probable level for adverse effects
effects in sensitive persons is 0.15 ppm.
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PROBABLE EFFECT LEVEL ESTIMATES
(Estimates for Sensitive Population Segments)
Aggravation of Asthma,
Emphysema, and Chronic
Bronchitis
Reduced Resistance in
Bacteria Infection -
(Animal Studies-)
Reduction in
Pulmonary Function
Chest Discomfort &
Irritation of the
Respiratory Tract
Health panel
judgment of
effect level
Probable or median
effect level as
estimated from
0.15 - 0.25 ppm
0.17 ppm
( 0.14 - 0.25 ppm)
Not available
0.18 ppm
( 0.07 - 0.38 ppm)
0.15 - 0.25 ppm
0.15 ppm
( 0.07 -0.18 ppm)
0.15 - 0.25 ppm
0.15 ppm
( 0.11 - 0.18 ppm)
health experts
(Range of estimates
given in parentheses)
It is not EPA's task, however, to identify a probable effects level.
EPA's task is to set an ambient air quality standard that protects the
public health and welfare with an adequate margin of safety. EPA must
therefore deal with the uncertainty inherent in the judgment that the
probable level for adverse effects in sensitive persons is 0.15 ppm.
Because the nature and intensity of effects vary from pollutant to
pollutant and because medical research produces new and different findings
as science progresses, EPA does not believe that a fixed acceptable margin
of safety can be established for all pollutants or for a single pollutant
over time. Each decision on a standard level must be made on the best
evidence available at the time and should include considerations of such
factors as:
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59
1. Concern for sensitive groups whose response to ozone may
be different than the response of less sensitive persons tested in
reported studies. Individuals with underlying respiratory illness
such as asthma, chronic bronchitis, and emphysema are particularly
sensitive to even modest impairments of pulmonary function resulting
from ozone exposure. There is real concern that effects reported
in some ozone studies may occur at lower concentrations, and may
be enhanced when ozone is in combination with other urban pollutants.
Laboratory studies of single pollutants (e.g., ozone in clean
filtered air), while important in elucidating physiological effects
peculiar to that pollutant, cannot be viewed as providing definitive
evidence of the minimum level at which these effects occur when the
source pollutant is present as only a part of the total insult delivered
to an individual in the urban environment. Thus, the effects of ozone
must be considered in the context of the total environment of the
exposed individual, including concentrations of other pollutants
consistent with their maximum allowable levels, high relative humidity,
high ambient temperatures, and high levels of physical stress.
2. Long-term deleterious effects of ozone — unfortunately, there
are few studies that have attempted to document the long-term adverse
effect of human exposure to repeated peaks of ozone. Some animal
studies do indicate that long-term oxidant exposures seem to act
as an inducer of biochemical or morphological changes. These
changes are transient, and, on a short-term basis, may have a
physiological significance in that they confer a resistance
against further lung injury in an oxidant environment (a similar
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60
response has been observed in human clinical studies). However,
the long-term effects of these changes resulting frorm continued
exposure are yet to be determined. Whether or not low-level
oxidant exposures can lead to enhanced aging, or development of
chronic bronchitis or pulmonary carcinoma, fibrosis, or emphysema
needs to be determined by long-term tests.
3. Animal Studies — although evidence of reduced resistance to
bacterial infection has not reached the point where it can be
meaningfully used to extrapolate concentrations that would similarly
affect man, these studies cannot be dismissed in selecting a
standard level that provides an adequate margin of safety.
Most experts agree that this affect does occur in humans, and
that it is only the concentration at which these affects occur
that is uncertain. Further, it is the kind of effect that is serious
enough in its implications to raise a need for caution. Thus,
it is prudent public health practice to set a standard more stringent than
the probable effect level estimated from human studies, in order to
account in some measure for these unquantified but possibly
serious effects.
4. Inconclusive Studies Reporting Effects at Low Levels — a similar
caution is suggested by both the Japanese epidemiological studies
and the German (von Nieding) clinical studies reporting effects
at levels around 0.10 ppm.
5. Uncertainties Arising from Variations in Air Quality Concentrations
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61
Due to Prevailing Meteorological Conditions — since EPA's revised
standard is statistically based and permits an expected number of
allowable violations per year, there is concerni about the magnitude
of these excursions and how they might impact an exposed sensitive
individual.
6. Findings from the Preliminary Risk Assessment— the preamble
to the proposed standard described a preliminary risk assessment
method performed to aid EPA in accurately treating the uncertainties
associated with a standard decision. While this method cannot be
used at this time as the sole tool for making that decision, we do
believe its findings suggest caution in any relaxation of the standard
above 0.10 ppm.
The Administrator has thoroughly considered the reported effects level,
the comments provided during the public comment period, and the cautions
signalled by uncertainties in the. medical evidence. Based on all these
data, EPA is revising the primary standard to 0.10 ppm.
WELFARE EFFECTS AND THE SECONDARY STANDARD
The Clean Air Act mandates the setting of a national secondary
ambient air quality standard to protect the public welfare from any
known or anticipated adverse effects associated with the presence of
an air pollutant in the ambient air. Ozone and other photochemical
oxidants constitute a form of air pollution that has been shown to
affect vegetation and materials, and that may have an impact on visibility.
The resultant economic loss has been estimated to be in the range of
several hundred million dollars per year nationwide. Non-quantifiable
losses to the natural environment occur as well. A staff paper,
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"Assessment of Welfare Effects and the Secondary Air Quality Standard
for Ozone," has been placed in the docket. The following material
summarizes that report and information received subsequent to its release.
Exposure of vegetation to harmful levels of ozone may result
in leaf injury, decreased growth and yield, or reproductive effects.
Visible leaf injury is the most readily detectable and frequently
reported symptom of ozone damage, this effect provides the best
available data base for evaluating alternative standard levels.
In the Federal Register proposal of June 22, 1978 (43 FR 26968 -26969)
it was stated that several investigators suggested that foliar injury
rates in the range of 5 to 10 percent could produce detectable reductions
in growth or yield, depending on the timing of the injury and other
environmental factors. Since proposal of the standard in June, EPA
has conducted further discussion with experts in the field of
air pollution damage to vegetation, as to what level of leaf injury
should be of concern in protecting against significant reductions
in yield or growth to commercially important crops and indigenous
flora. These experts emphasized the uncertainty associated with
correlating yield reduction with foliar injury. Some stated that
detectable yield reductions would not occur until leaf injury reached
values as high as 10 to 20 percent and others felt that foliar
injury was an inappropriate indicator of yield reduction.
The effects of ozone on vegetation are not linearly dependent on
the dose (product of concentration" and exposure duration) sustained by
the plant. A given dose applied over a short period of time is more
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63
damaging than if it were applied over a longer period. A mathematical
model has been used to summarize for several crops the experimental
results which depict the variation in foliar response with short-term
(0.5-hour to 8-hour) ozone exposures. The proposed rule stated that a
secondary ozone air quality standard set at an hourly average con-
centration of 0.08 ppm, expected to be exceeded only once per year,
was predicted (based on the mathematical model) to prevent any
important commercial crop from receiving more than 3 percent leaf injury.
The following factors have led EPA to reassess the reasonableness
and uncertainties associated with the judgments that led to the
proposed 0.08 ppm 1-hour average secondary standard. First, there are
potentially large incremental control costs associated with a secondary
standard more stringent than the primary standard. Second, the rationale
for the proposed secondary standard was brought into question by field
measurements at some remote sites where man-caused ozone is likely to be
negligible. Spring-time monthly averages ranging up to about 0.05 ppm
and maximum hourly averages up to 0.08 ppm were reported at these
sites. Third, there are large uncertainties involved in the
assumptions relating yield reduction to foliar injury. The mathe-
matical model employed to predict foliar injury was based on chamber
studies, not real field conditions. EPA has been cautioned by various ex-
perts that these studies generally represent experimental conditions using
the most sensitive varieties of a given species and optimum moisture and
temperature conditions for producing injury. In addition, a given dose of
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64
ozone which can produce 5, 10, or even 20 percent foliar injury in a
given plant is unlikely to have an impact on yield unless the exposure
occurs during the critical stage of growth in the plant's life cycle.
As part of EPA's reassessment, a limited economic analysis (included
in the docket) has been conducted by the Agency to estimate the maximum
benefits to be obtained by adoption of a secondary standard more stringent
than the primary standard. Employing worst case assumptions with regard
to damage to vegetation, the analysis indicates that a secondary standard
more stringent than the primary does not appear necessary at this
time based on ozone-related damage to vegetation.
Materials damage due to ozone can be described as an acceleration
of aging processes, that is, rubber cracking, dye fading, and paint
weathering. In contrast to the effects of ozone on vegetation, these
effects are linearly dependent on the ozone dose sustained by the
material. As a result, the annual average concentration, not the short-
term peak exposure, will determine the rate at which material damage
occurs. Any nonzero ozone concentration (including natural background
levels) will contribute to the deterioration of sensitive materials over
a sufficiently long exposure duration. While peak 1-hour concentra-
tions of ozone tend to be higher in urban areas, rural areas remote from
man-made emission sources have been found to have similar annual
average concentrations. This is due to the nighttime scavenging of
ozone by man-made pollutants in the urban areas. Reducing the
hourly peak exposure of ozone is not likely to result in a detectably lower
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annual average. Therefore, a secondary standard more stringent than
the primary air quality standard will not reduce economic damage to
materials.
For the above reasons, no effect-based rationale can be offered
to decide the level of the secondary standard needed to protect materials.
Additionally, on the basis of information presented in the 1977 NAS ozone
document, EPA believes that little if any effect on visibility results from
these low ozone exposures. Based on the preceding considerations, EPA
has concluded that a secondary standard more restrictive than the primary
air quality .standard does_ not _appeajr j»ecessary at_this time._ Therefore,.
EPA is_revising the_s_econdary ai^ qualjty standard level^ for ozone
to 0.10 ppm.
OTHER ASPECTS OF THE STANDARD
Based on EPA's evaluation of evidence submitted and comments received
during the public review process, no major changes will be made in the
following aspects of the standard: (1) averaging time — 1 hour, (2)
chemical species — ozone, (3) form — statistical, and (4) a separate
standard for PAN is not being promulgated. As discussed below, minor
changes will be made in the form of the standard and the definition of
compliance will focus on a calendar day of hours above the standard
and not on a single hour.
Form of the Standard
In an attempt to account for the random nature of meteorological
variations, the present deterministic standard permits a single hourly
exceedance per year. In order to better account for these variations, EPA
-prgpr^ad-fr.ft-mftAi£y_i--ho_JLLanriard hy expressing it in a statistical form;
a further improvement is now being made based
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66
on comments received on the proposed standard. This improvement is
to employ a daily interpretation when determining the number of times the
standard has been exceeded. The proposed standard was structured in terms of
the number of hours exceeding the level of the standard. As indicated in
the proposal, there were certain advantages to employing a daily interpreta-
tion whereby a day is said to exceed the standard if the maximum hourly value
for the day exceeds the level of the standard. Based upon comments received,
it is evident that there is considerable support for the use of this
daily interpretation. The reason most commonly advanced for this
change was the dependence of successive hourly ozone values due to
meteorological factors. In addition, for a secondary pollutant such as
ozone there is a time lag between the associated emissions and the measured
ozone values. Consequently, once a high hourly ozone value above the level of
the standard is recorded there is little that can be done to immediately
reduce the next hourly value. A final consideration is that precursor
emissions are not easily manipulated on a short-term basis. This limits
the likelihood that emission sources could readily alter emission patterns
to take advantage of the daily, rather than hourly, interpretation. In
view of these factors, the ozone standard has been restructured in terns of
days exceeding the level of the standard.
A modification has also been made to the exclusion criteria for missing
data. The proposed standard permitted certain missing values to be excluded
from the estimated exceedances calculation if either of two exclusion
criteria were satisfied. The first criterion dealt with the magnitude
of adjacent values to reflect short-term meteorological influences. This
should be relatively easy to incorporate into data-handling schemes and
has been retained, although it now applies to daily values. The second
criterion dealt with comparisons with data from the previous three years.
The purpose of this second criterion was to accommodate situations for
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which ozone data for a particular season is not available and yet known
seasonal patterns of ozone and related meteorological factors make it
unlikely that the level of the standard would have been exceeded. This
second criterion would be more difficult to implement because it necessitates
the cross-referencing of earlier historical data. It also requires that
historical data must be available in order to invoke this exclusion.
Thus this second criterion in the proposal is difficult to implement and
could be potentially burdensome in geographic areas where the climate
makes high ozone values during certain seasons very unlikely. It is also
possible to accomplish the intended purpose of this exclusion through
provisions of 40 CFR 58 which would grant waivers of the ozone monitoring
requirements for certain times of the year at the discretion of the appro-
priate Regional Administrator. Therefore, the second exclusion criterion
has been eliminated and the computation formulas have been modified to
reflect the number of required monitoring days for the year.
Definition of When the Standard is Attained — EPA is adding Appendix H to
40 CFR 50 to explain when the standard is or is not being attained.
Certain modifications to the proposal were necessary to accommodate
the daily interpretation and the previously mentioned changes in the
treatment of missing data. In order to implement a daily, rather than
hourly, interpretation it is necessary to define what is meant by a valid
day of ozone data. Such a definition must ensure that a sufficient number
of hours of the day have been monitored and that the hourly values in
question reflect the time of day when high ozone values are likely to
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occur. At the same time, this criterion should be relatively easy
to implement, it should allow time for routine maintenance, and yet
protect against high values being ignored merely because not enough
hours of the day were measured. In view of this, a daily maximum
will be considered valid if 75 percent of the hourly values from
9:01 a.m. to 9:00 p.m. (LSI) were recorded or if an hourly value above
the level of the standard was measured. This validity criterion is in-
tended as a minimum requirement and not as a recommended schedule.
The computation formula for calculating the estimated number of
exceedances per year has been modified to correspond to the daily
interpretation of the standard. Allowance has also been made for any situa-
tion in which the Regional Administrator has granted a waiver of the
ozone monitoring requirements under the provisions of the newly proposed
40 CFR 58 (43 FR 34892) and therefore the total number of required monitoring
days is less than a full year. The use of the exclusion criterion may result
in an underestimate of the probability of an exceedance in some situations
but is relatively easy to implement and should suffice to account for the
effect of missing data. It should be noted that the formula given in
Appendix H is necessary to show attainment. However, accounting for
missing data can never decrease the number of exceedances and thus it
is possible to establish non-attainment without the use of this equation.
These modifications to Appendix H are intended to somewhat simplify
the calculations and allow for more flexible monitoring schedules. The
comments received on Appendix H were varied. A few thought it was too
complicated while others suggested even more complex techniques. However,
most comments were either supportive of the proposed approach, or at least
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neutral. One suggestion was to employ a minimum percent completeness
requirement, rather than estimating the number of exceedances. However,
the problem with that type of approach is that it remains unclear as to
what should be done with data sets that fail to meet such a complete-
ness requirement.
Some comments addressed the use of three years of data. As indicated
in the proposal, the choice of a three year period represents a compromise
between added stability and reasonably current status assessments. It is
worth noting that even under the previous once per year standard, attainment
designations (e.g. 40 CFR 81-107) were based on more than one year.
Although three years are used, it is still possible to establish non-
attainment after one year if, for example, four or more exceedances
were reported. Therefore, an upper bound to exceedances during a
single year still applies under the new form.
ECONOMIC, ENERGY, AND ENVIRONMENTAL
IMPACTS
As has been noted previously, the Clean Air Act specifically
requires that National Ambient Air Quality Standards be based on
scientific criteria relating to the level that should be attained to
adequately protect public health and welfare. EPA interprets the Act
as excluding any consideration of the cost of achieving such a standard
in determining the level of the standard. However, in compliance with
the requirements of Executive Orders 11821 and 11949 and OMB Circular
A-107 and with the provisions of the recently issued Executive Order
12044 for rulemaking proceedings which are currently pending, EPA has
prepared an analysis of economic impacts associated with efforts to
attain this standard.
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Ozone air pollution is a pervasive problem throughout the country.
Most urban and many rural areas exceed the existing standard. Even with
the less stringent standard, most of the major urban areas are not
expected to attain the standard in the near-term. Control of the
organic precursor materials which generate photochemical oxidants
is a major effort in this country and a multi-billion dollar program.
The existing control program includes measures to reduce organic emissions
from: automobile and truck exhausts, production of chemical and petroleum
products, the dry-cleaning industry, most painting operations including the
automotive industry, and other industrial operations.
Because the attainment problem in most urban areas is so severe,
the relaxation of the standard is "not expected to change the level of
control requirements in the near-term. However, the move to a 0.10 ppm
standard will eliminate the need for major control programs in many rural
and wilderness areas which currently exceed the standard.
With the relaxation of the standard, the longer-range outlook
does indicate that many urban areas will achieve the standard by 1987.
However, even with aggressive control programs, it will be very difficult
for some urban areas to achieve the standard within the next 10 years.
In addition, a document has been prepared assessing the impacts
that efforts to attain the standard may have on the nation's energy
requirements. Control of oxidant precursors will often be accomplished
by recovery of organic materials that would otherwise be emitted to the
atmosphere. Because of such energy savings, this document concludes
that oxidant precursor control measures may well lessen the nation's
energy requirements.
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Furthermore, environmental impacts associated with control of
oxidant precursors have been examined in a document available in
docket number OAQPS 78-8. This study indicates that modifying the
current standard should have minimal environmental impacts..
Copies of the above-mentioned analyses of the economic,
energy, and environmental impacts involved in the revised ozone
standard are available from EPA at the address given earlier.
REVISIONS TO PART 50 REGULATIONS
In addition to the revised standard, this action necessitates two
other revisions to Part 50 as follows:
1. In Appendix D, as well as in the table of sections for
Part 50, the title is revised to read as follows: "Appendix D -
Measurement Principle and Calibration Procedure for the Measurement
of Ozone in the Atmosphere." The substitution of "ozone" for "photo-
chemical oxidants corrected for interferences due to nitrogen oxides
and sulfur dioxide" is a result of the proposed change in the
chemical designation of the standard.
2. Appendix H, "Interpretation of the National Ambient Air Quality
Standard for Ozone", is added because additional guidance is
necessary to understand the statistical nature of the revised
standard.
REVISIONS TO PART 51 REGULATIONS
Elsewhere in this issue of the Federal Register, three revisions to
Part 51 are promulgated concurrently with the revision to the photochemical
oxidant standard. They are as follows:
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1. The term "photochemical oxidants" is changed to "ozone"
throughout Part 5J.
2. Section 51.14, "Control strategy: Carbon monoxide, hydro-
carbons, photochemical oxidants, and nitrogen dioxide", is revised
to allow the states to use any of four analytical techniques in
the place of Appendix J to calculate the percent hydrocarbon reduction
needed to attain the ozone standard.
3. Appendix J is deleted from Part 51.
FEDERAL REFERENCE METHOD
The measurement principle and calibration procedure applicable to
reference methods for measuring ambient ozone concentrations to determine
compliance with the standard are not affected by this rulemaking. Else-
where in this issue of the Federal Register, however, EPA is replacing
(superseding) the current calibration procedure with a new, superior
calibration procedure based on ultraviolet photometry. The measurement
principle and the current calibration procedure are set forth in Appendix
D of 40 CFR Part 50 (as amended in the February 18, 1975 issue of the
Federal Register, 40 FR 7042). Reference methods — as well as equivalent
methods — for monitoring ozone are designated in accordance with 40 CFR
Part 53 (40 FR 7044). A list of all methods designated by EPA as reference
or equivalent methods for measuring ozone is available from any EPA regional
office, or from EPA, Department E (MD-76), Research Triangle Park, NC 27711.
Date Administrator
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73
EPA amends Part 50 of Chapter I, Title 40, of the Code of Federal
Regulations as follows:
1. Section 50.9 is revised as follows:
§ 50.9 National primary and secondary ambient air qua-lity
standards for ozone.
(a) The level of the national primary and secondary ambient air
quality standards for ozone measured by a reference method based
on Appendix D to this part and designated in accordance with Part
53 of this chapter, or by an equivalent method designated in
accordance with Part 53 of this chapter, is 0.10 part per million
(196 yg/m ). The standard is attained when the expected number of
days per calendar year with maximum hourly average concentrations
above 0.10 part per million ("196 yg/m3) is equal to or less than
one, as determined by Appendix H.
2. In Appendix D, as well as in the table of sections for Part 50,
the title is revised to read as follows: Appendix D — Measurement
Principle and Calibration Procedure for the Measurement of Ozone
in the Atmosphere.
3. Appendix H is added as follows:
APPENDIX H - INTERPRETATION OF THE NATIONAL AMBIENT AIR
QUALITY STANDARD FOR OZONE
1. General
This appendix explains how to determine when the expected number
of days per calendar year with maximum hourly concentrations above
0.10 ppm (196 yg/m3) is equal to or less than one. An expanded discussion
of these procedures and associated examples are contained in the "Guide-
line for Interpretation of Ozone Air Quality Standards." For purposes
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74
of clarity in the following discussion, it is convenient to use the
term "exceedance" to describe a daily maximum hourly ozone measurement
that is greater than the level of the standard. Therefore, the phrase
"expected number of days with maximum hourly ozone concentrations above
the level of the standard" may be simply stated as the "expected number
of exceedances".
The basic principle in making the above determination is
relatively straightforward. Most of the complications that arise
in determining the expected number of annual exceedances are
consequences of accounting for incomplete sampling. In general, the
average number of exceedances per calendar year must be less than or
equal to 1. In its simplest form, the number of exceedances at a monitoring
site would be recorded for each calendar year and then averaged over the
past three calendar years to determine if this average is less than or
equal to 1.
2. Interpretation of Expected Exceedances
The ozone standard states that the expected number of exceedances
per year must be less than or equal to 1. The statistical term
"expected number" is basically an arithmetic average. The following
example explains what it would mean for an area to be in compliance
with this type of standard. Suppose a monitoring station records a
daily maximum ozone value for every day of the year during the past
three years. At the end of each year, the number of days with maximum
hourly concentrations above 0.10 ppm is determined and this is averaged
with the results of previous years. As long as this average remains
"less than or equal to 1" the area is in compliance.
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3. Estimating the Number of Exceedances for a Year
In general, a value may not be available for eachi hour of the
year and it will be necessary to account for these missing values
when estimating the number of exceedances for a particular calendar
year. It should be noted that the purpose of these computations is
to determine if the expected number of exceedances per year is less
than or equal to 1. Thus, if a site has two or more observed
exceedances each year, the standard is not met and it is not necessary
to use the procedures of this section to account for incomplete sampling.
The term "missing value" is used here in the general sense to de-
scribe all days that do not have an associated ozone measurement. In
some cases, a measurement might actually have been missed but in other
cases no measurement may have been scheduled for that day. A daily
maximum ozone value is defined to be the highest hourly ozone value
recorded for the day. This daily maximum value is considered to be
valid if 75 percent of the hours from 9:01 a.m. to 9:00 p.m. (1ST) were
measured or if the highest hour is greater than the level of the standard.
In some areas the seasonal pattern of ozone is so pronounced that
entire months need not be sampled because it is extremely unlikely that
the standard would be exceeded. Any such waiver of the ozone monitoring
requirement will be handled under provisions of the newly proposed 40 CFR
58. To avoid unfairly penalizing such areas, some allowance must be made to
allow for days that were not actually measured but would quite likely have
been below the standard. This introduces a complication in that it
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76
becomes necessary to define under what conditions a missing value
may be assumed to have been less than the level of the standard. The
following criterion may be used for ozone:
A missing daily ozone value may be assumed to be less than the
level of the standard if both the daily maximum preceding and the
daily maximum following this missing day do not exceed 75 percent of
the level of the standard.
Let z denote the number of missing daily values that may be
assumed to be less than the standard. Then the following formula
shall be used to estimate the expected number of exceedances for the
year:
e = v +[(v/n) * (N-n-z)] (1)
(Indicates multiplication)
Where
e = the estimated number of exceedances for the year.
N = the number of required monitoring days in the year
n = the number of valid daily maxima
v = the number of daily values above the level of the standard
z = the number of days assumed to be less than the standard level
This estimated number of exceedances shall be rounded to
one decimal place (fractional parts equal to 0.05 round up).
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It should be noted that N will be the total number of days
in the year unless the appropriate Regional Administrator has granted
a waiver under the provisions of 40 CFR 58.
The above equation may be interpreted intuitively in the
following manner. The estimated number of exceedances is equal to
the observed number of exceedances (v) plus an increment that accounts
for incomplete sampling. There were (N-n) missing values for the
year but a certain number of these, namely z, were assumed to be less
than the standard. Therefore, (N-n-z) missing values are considered to
include possible exceedances. The fraction of measured values that are
above the level of the standard is v/n. It is assumed that this same
fraction applies to the (N-n.-z) missing values and that (v/n)*(N-n-z)
of these values would also have exceeded the level of the standard.
4. Use of multiple years of data. - Ideally, the expected number
of exceedances for a site would be computed by knowing the probability
i
that the site would record 0, 1, 2, 3 ... exceedances in a year. Then
each possible outcome could be weighted according to its likelihood of
occurrence and the appropriate expected value, or average, could'be com-
puted. In practice, this type of situation will not exist because ambient
data will only be available for a limited number of years.
Consequently, the expected number of exceedances per year at a site
shall be computed by averaging the estimated number of exceedances for
each year of available data during the past three calendar years. In
other words, if the estimated number of exceedances has been computed
for the calendar years of 1974, 1975, and 1976 then the expected number
of exceedances is estimated by averaging those three numbers. If
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this average is greater than 1, then the standard has been exceeded at
this site. It suffices to carry one decimal place in this computation.
For example, the average of the three numbers 1, 1 and 2 is 1.3 which
is greater than 1. If data is not available for each of the- last three
years then this average shall be computed on the basis of available
data from the remaining years in that period.
AUTHORITY: Sections 109 and 301 of the Clean Air Act, as amended
(42 U.S.C. 7409, 7601).
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References
Bell, K. A., W. S. Linn, M. Hazucha, J. D. Hackney, and 0. V.
Bates. "Respiratory effects of exposure to ozone plus sulfur
dioxide in Southern Californians and Eastern Canadians." Am. Ind.
Hyg. Assoc. J. 38: 696-706, 1977.
Brinkman, R., H. B. Lamberts, and T. S. Veninga. "Radio-mimetic
toxicity of ozonized air," Lancet J_ (7325): 133-136, 1964.
DeLucia, A. J., and W. C. Adams. "Effects of 03 inhalation during
exercise on pulmonary function and blood biochemistry." J. Appl.
Physiol.: Respirat. Environ. Exercise Physiol. 43 (1): 75-81, 1977.
____ _ __j__ f _-mw __ ^^^™ k.
Durham, W.H. "Air pollution and student health." Arch. Environ.
Health. 28: 241-254, 1974.
Follinsbee, L. J., F. Silverman, and R. J. Shephard. "Exercise
responses following ozone exposure." J. Appl. Physiol. 38_: 996-1001, 1975.
Hackney, J. D., W. S. Linn, and others. "Experimental studies on
human health effects of air pollutants." Arch. Environ. Health 30_: 373-
390, 1975.
Hammer, 0. I., V. Hasselblad, B. Portnoy, and P. F. Wehrle. "The
Los Angeles student nurse study." Arch. Environ. Health 28: 255-260, 1974.
Hazucha, M. "Effects of ozone and sulfur dioxide on pulmonary
function in man." Ph.D. Thesis. McGill University, Montreal, Canada.
1973. 233 p.
Hazucha, M., and D. V. Bates. "Combined effect of ozone and sulfur
dioxide on human pulmonary function." Nature 257 (5521): 50-51, 1975.
Hazucha, M., F. Silverman, C. Parent, S. Field, and D.V. Bates.
"Pulmonary function in man after short-term exposure to ozone." Arch,
Environ. Health 27^: 183-188, 1973.
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Kagawa, J., and T. Toyama. "Photochemical air pollution:
Its effects on respiratory function of elementary school children."
Arch. Environ. Health 30: 117-122, 1975.
Kagawa, J., T. Toyama, and M. Nakaza. "Pulmonary function tests in
children exposed to air pollution." In: Clinical Implications of Air
Pollution Research. A. J. Finkel and W. C. Duel (eds.). Acton, MA. Pub-
lishing Sciences Group, Inc. 1976. pp. 305-320.
Kurata, J. H., M. M. Glovsky, R. L. Newcomb, and J. G. Easton.
"A multi-factorial study of patients with asthma. Part 2: Air pollution,
animal dander and asthma symptoms." Annals of Allergy. 37: 398 - 409,
1976.
Lagerwerff, J. M. "Prolonged ozone inhalation and its effects
on visual parameters." Aerospace Med. 34: 479-489, 1973.
Linn, W. S., R. D. Buckley, C. E. Spier, R. L. Blessey, M. P. Jones,
D. A. Fischer, and J. D. Hackney. "Health effects of ozone exposure in
asthmatics." Amer. Rev. Resp. Dis. 117: 835-843, 1978.
Makino, K., and I. Mizoguchi "Symptoms caused by photochemical
smog." Japanese Journal of Public Health 22_ (8): 421-430, 1975.
National Academy of Sciences - National Academy of Engineering.
"Air Quality and Automobile Emission Control." Report for the 93rd
Congress, 2d Session, Serial Number 93-24. Prepared for the U.S. Senate
Committee on Public Works by the Coordinating Committee on Air Quality
Studies, September 1974.
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National Academy of Sciences. Ozone and Other Photochemical Oxidants.
Prepared by the Committee on Medical and Biologic Effects of Environ-
mental Pollutants, National Academy of Sciences. Washington, D.C. 1977.
"Report of the U.S. House of Representatives Committee on Interstate
and Foreign Commerce on the Clean Air Act Amendments of 1977." H.R.
Report 95-924, 95th Congress, 2d. Session, pp. 110-112.
Schoettlin, C. E., and E. Landau. "Air pollution and asthmatic
attacks in the Los Angeles area." Public Health Repts. 76: 545-548, 1961.
Silverman, F., L. J. Folinsbee, J. Barnard, and R. J. Shephard.
"Pulmonary function changes in ozone — interaction of concentration and
ventilation". J. Appl. Physiol. 41. (6): 859-864, 1976.
U.S. Department of Health, Education, and Welfare. Air Quality
Criteria for Photochemical Oxidants. National Air Pollution Control
Administration, Public Health Service, U.S. DHEW. NAPCA Publ. AP-63.
Washington, DC. U.S. Government Printing Office. 1970.
U.S. Environmental Protection Agency. Air Quality Criteria for
Ozone and Other Photochemical Oxidants. Preprint. U.S. EPA Publ.
EPA-600/8-78-004. Washington, DC. April 1978.
von Nieding, A.,_H.M. Wagner, H.L. Loellgen, and H. Krekeler.
Presented at the VDI Kommission Reinhaltung der Luft Colloquim on
Ozone and Related Substances in Photochemical Smog, Duesseldorf, W.
Germany, September 22-24, 1976.
Wayne, W.S., P.F. Wehrle, and R.E. Carroll. "Pollution and
athletic performance." J. Amer. Med. Assoc. 199 (12): 901-904, 1967.
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TAB B
ENVIRONMENTAL PROTECTION AGENCY
[40 CFR Part 50]
i
MEASUREMENT OF OZONE IN THE ATMOSPHERE P.-otacL:^ P-. -re
Calibration of Ozone Reference Methods nc« . ,
UtL «.. ^ J.97c
LIBRARY
AGENCY: U.S. Environmental Protection Agency
ACTION: Final rule.
SUMMARY: Appendix D to 40 CFR Part 50 prescribes a measurement
principle upon which reference methods for the measurement of ozone*
in the atmosphere must be based. This appendix also specifies a
procedure to be used for calibrating those ozone reference methods.
EPA has evidence that another calibration procedure for ozone refer-
ence methods is significantly more accurate and less variable than
the procedure currently specified in Appendix D. Accordingly, EPA
is amending 40 CFR Part 50, Appendix D, to replace (supersede) the
current calibration procedure with a superior calibration procedure
based on ultraviolet photometry.
DATES: Effective date: [30 days after publication in the FEDERAL
REGISTER].
*The term "ozone" is used herein to be consistent with another EPA
action in this issue of the FEDERAL REGISTER substituting "ozone"
for "photochemical oxidants corrected for interferences due to
nitrogen oxides and sulfur dioxide," which was formerly used in
Part 50.
1
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FOR FURTHER INFORMATION CONTACT: Mr. Larry J. Purdue,
Telephone 919-541-2666 (FTS: 629-2666).
ADDRESS: Department E (MD-77)
Environmental Monitoring and Support Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
SUPPLEMENTARY INFORMATION:
Background
Part 50 of Title 40, Chapter I of the Code of Federal Regula-
tions specifies the National Ambient Air Quality Standards for
several air pollutants including ozone. Appendices to Part 50
provide information concerning the reference methods which are
used to measure those pollutants. In particular, Appendix D to
Part 50 describes a measurement principle upon which ozone refer-
ence methods must be based, and specifies a calibration procedure
to be used for calibrating such methods. Previously, the calibra-
tion procedure specified by Appendix D was based on assay of ozone
with 1% neutral buffered potassium iodide (NBKI) and was known as
the "NBKI procedure."
On June 22, 1978, EPA indicated its conclusion that another
calibration procedure was clearly superior to the NBKI procedure,
and accordingly EPA proposed an amendment to Appendix D to replace
the NBKI procedure with the new procedure, based on ultraviolet (UV)
photometry (43 FR 26971-26984). The rationale for the proposed
amendment was discussed in the preamble to that proposal.
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Interested persons and organizations were afforded an opportunity
to comment on all aspects of the proposed changes. The amendment,
revised slightly after consideration of the public comments, is
being promulgated today in conjunction with related changes in the
ambient air quality monitoring requirements appearing elsewhere in
this issue of the FEDERAL REGISTER.
Nature of Changes
The amendment makes three salient changes to the previous
requirements for calibration of ozone reference methods. These
are as follows:
(1) The NBKI calibration procedure is superseded by a pro-
cedure based on UV photometry for the calibration of reference
methods for ozone. Since no National Bureau of Standards (HBS)
Standard Reference Material is available for ozone, ozone standard
concentrations established via the UV procedure are tantamount to
primary ozone standards, and the UV procedure itself is thus
referred to as a "UV standard" for ozone.
(2) Independent use of a manual KI procedure known as the
"BAKI procedure" in lieu of the UV procedure is allowed for 18
months after the effective date of the amendment, with the recom-
mendation that the BAKI technique be related to a UV standard
whenever possible.
(3) The use of alternative procedures as transfer standards
is specifically allowed if they meet certain transfer standard
performance guidelines set forth by EPA. A transfer standard is
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any device or procedure which can be referenced to a UV ozone
standard and then used at another location to reproduce ozone
standards. A practical transfer standard offers some important
advantages—such as lower cost, ruggedness, easier operation, or
convenience—over direct use of the UV procedure.
New UV Calibration Procedure
The new UV calibration procedure is quite simple. After
generating a stable, dynamic ozone concentration with an ozone
generator, the operator assays it by passing all or a portion of
the gas flow through the cell of a UV photometer. The photometer
readings are then used in a formula to calculate the ozone concen-
tration, which as noted earlier, is effectively a primary ozone
standard. Most commercially available photometers do the photo-
metric calculations automatically, and some may also make tempera-
ture and pressure corrections automatically. The primary burden
on the operator is to insure (1) that the photometer is operating
correctly, (2) that the apparatus is set up properly and is clean
and leak-free, and (3) that the calculations are complete and
accurate. While none of these is particularly difficult, EPA has
prepared a Technical Assistance Document which explains these tasks
and provides other detailed information about the procedure. This
document, which is still in draft form to allow further incorpora-
tion of user's comments, is available from the address specified at
the beginning of this preamble.
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The photometer is obviously of critical importance to the
procedure and must have a precision within 0.005 ppm or 3% of the
concentration, whichever is greater. While a calibration photom-
eter can be assembled from laboratory components, EPA recommends
the purchase of a commercial photometer which is either designed
specifically for this calibration procedure, or which can be readily
adapted to it. EPA is presently aware of 2 such commercial pho-
tometers (available from Dasibi Environmental Corp., Glendale,
California, and Science Applications, Inc., La Jolla, California)
and expects others will become available in the future.
UV photometers of the type used in ambient ozone analyzers
are likely to be suitable as calibration photometers. Conversion
of an ambient UV analyzer to a calibration photometer is covered
in the Technical Assistance Document mentioned above. However, it
is important to differentiate between the use of a UV photometer as
an ambient analyzer and its use as a calibration photometer. This
distinction is predicated more on operational differences than on
any specific physical differences. The new calibration procedure
requires that a photometer used for calibration must be dedicated
exclusively to such use, must be maintained under meticulous con-
ditions, and must De used only with clean, calibration gases. UV
analyzers used for ambient monitoring should always be calibrated
wHh an independent calibration photometer or a certified transfer
standard. A UV analyzer should not be considered to be "self-
calibrated" even though it contains a UV photometer which meets the
-------
specifications of the UV calibration procedure.
New BAKI Calibration Procedure
The new BAKI calibration procedure is very similar to the pre-
viously specified NBKI procedure. Relatively minor modifications
provide somewhat less variability than the NBKI procedure. Agencies
which are famili-ar with the NBKI procedure should have no difficulty
switching to the BAKI procedure. Independent use of the BAKI pro-
cedure is allowed only for direct calibration of ozone analyzers
(not transfer standards) on a temporary basis during the 18-month
transition period to permit agencies to adopt the new, UV calibra-
tion procedure. Nevertheless, the BAKI procedure has more varia-
bility than the UV procedure. Therefore, EPA would urge agencies
to adopt the UV procedure as soon as practical. And, when possible,
the BAKI procedure should be related to the UV procedure to improve
the overall accuracy.
Following the 18-month period, the BAKI procedure will not
be authorized for independent use, but can be used as a transfer
standard. As such, it must be related to the UV procedure, and its
variability and accuracy must be monitored and controlled. Thus,
agencies which find the BAKI procedure advantageous could continue
to use this procedure as a transfer standard.
Transfer Standards
EPA is specifically allowing transfer standards for calibrating
ozone analyzers, and has noted a number of advantages which can be
6
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realized by their use. Transfer standards for ozone can include
procedural techniques such as BAKI and gas phase titration, as well
as devices such as ozone analyzers and stable ozone generators.
EPA recommends that agencies consider the use of transfer standards
where advantageous. But transfer standards must meet certain per-
formance specifications, and their performance must be monitored.
EPA has prepared a Technical Assistance Document on "Transfer
Standards for Calibration of Ambient Air Monitoring Analyzers for
Ozone," which gives the required performance specifications and
general guidance on the certification and use of any type of trans-
fer standard for ozone. This document is also still in draft form
to allow incorporation of further user's comments, and a copy of it
may be obtained from the address given at the beginning of this
preamble.
SUMMARY OF COMMENTS RECEIVED
AND CHANGES MADE TO FINAL AMENDMENT
Comments relative to the proposed amendment (43 FR 26971) were
received from 26 respondents representing EPA Regional Offices,
State and local air pollution control agencies, industrial corpora-
tions, and other organizations. Almost all of the respondents ex-
pressed general support for the proposed change to the UV photometric
calibration procedure. Other comments ranged from issues of basic
policy to technical aspects of the proposed amendment. After
-------
consideration of all the comments, several minor revisions and
improvements were made to the proposed amendment, although the
basic principles and objectives have not been altered. Specific
changes to the proposed amendment are discussed briefly below.
A document containing a summary of all the comments received, the
identity of the respondents, the resulting changes made to the
amendment, and the rationale for adoption or rejection of each
comment is available from the address given at the beginning of
this preamble. This document will also be added to Docket No.
OAQPS 78-8, which is available for public inspection during normal
business hours at the USEPA, Public Information Reference Unit,
Room 2922 (EPA Library), 401 M. Street, S.W., Washington, DC 20460.
Several respondents pointed to the relatively high cost of
implementing the change in calibration procedures and suggested
that EPA should either provide the necessary funds to those
agencies with nonattainment and unclassified areas, or make
available, in each EPA Region, a reference photometer that could
be used to certify appropriate transfer standards. Other comments
suggested a similar need for such reference photometers until
such time that commercial photometers become more generally
available. EPA agrees with these general comments and intends to
pursue them, but this requires no actual change to the amendment
as proposed.
Many of the comments indicated a concern for a lack of
reliability in present commercial UV systems. Some of these same
8
-------
respondents recommended revisions in the UV calibration procedure to
incorporate procedures for checking or calibrating the photometer's
wavelength, path length, and optical density (or absorbancy).
However, EPA believes that the reliability of most commercial
photometers will be adequate. The photometer specifications
require a non-dispersive optical system which is not likely to
experience changes in the wavelength. Path length is normally
fixed and should be adequately specified by the photometer manu-
facturer. Optical density checks with neutral density filters
(for example) are not practical because of the extremely small
optical density range over which the photometer normally operates.
The only practical way to check the response of the photometer is
with an absorbing gas such as ozone. The linearity test described
in Section 5.2.3 serves this purpose.
There was some concern for whether the absorption coefficient
of ozone at 254 nm (given in the procedure as 308 +_4 atm" cm"
at 0°C and 760 torr) might be different at different temperatures.
Other comments indicated that the corrections for temperature and
pressure in the UV photometeric assay procedure were not always
clear. The absorption coefficient of ozone is, in fact, quite
insensitive to temperature between 0 and 40°C--aside from the
normal effect of gas density change with temperature. For
photometers used at temperatures and pressures other than 0° and
760 torr, corrections are required according to the perfect gas
laws. Efforts are being made to further clarify these correction
-------
procedures in the ozone calibration Technical Assistance Document
mentioned earl ier.
A series of comments from one respondent recommended revisions
to the proposed procedure to more clearly allow the use of other
UV photometer designs and other configurations of components
within the UV calibration system. It was further pointed out
that, with certain configurations, some of the components shown
in the suggested configuration might not be necessary, and some
of the procedural steps in the proposed procedure might not be
necessary or even possible. This respondent questioned whether
UV photometer linearity tests by the user are necessary if the
manufacturer of the photometer has already done the tests.
Modification of the commercial photometer might be necessary to
carry out the tests and any resultant leaks in the system or
improper dilution techniques might confuse the results.
In response to these comments, EPA has revised Sections 3,
3.2, and 5.3 somewhat to more explicity allow alternate systems
or system configurations and to provide for appropriate variations
in the procedural steps to accommodate such systems. Also,
Section 5.2.3 on linearity has been changed to allow acceptance
of the manufacturer's linearity test in lieu of the user-conducted
test if the manufacturer can show that the linearity error is
less than 3%. When the user carries out the test, the error
specification remains at 5% to allow for some variation in the
necessary flow measurements.
10
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There were several comments regarding the BAKI calibration
procedure and its use for an interim period of 18 months. One
respondent questioned the wisdom of changing from a known procedure
(NBKI) to an unknown procedure (BAKI) and then changing again to
UV photometry within 18 months. The respondent recommended that
EPA allow the continued use of the NBKI procedure on an interim
basis until the change to UV photometry can be implemented.
Another respondent questioned the necessity of allowing the
considerably more variable (than UV photometry) BAKI procedure
for the interim period, and recommended that comments from State
and local agencies directly affected should guide EPA in this
area.
EPA agrees that the BAKI procedure is more variable than the
UV procedure bur believes thar seme t-ansition period is necessary
before the UV procedure is required exclusively. There were few
comments to the contrary. EPA considered allowing continued use
of the NBKI procedure during the transition period, but the BAKI
procedure is really only a slightly modified version of the NBKI
procedure and is thus very similar. Since the change from NBKI to
BAKI is so easily made, and the performance of the BAKI procedure is
significantly better than the NBKI procedure, EPA feels the interim
change to BAKI is adequately justified.
11
-------
A few relatively minor changes were made to the BAKI procedure
in Sections 1, 3.8, 4.4.4, and 4.4.5 where respondents suggested
a need for clarification or where various improvements to the
method could be realized. For example, the units given as "eq"
in equation 5a of the BAKI were changed to "equivalents" in order
that they not be confused with equivalent weight. Also, the
concentration of the hydrogen peroxide added in Section 3.8 has
been increased slightly and the specification for the resulting
absorbance increase has been reduced from 0.010 to 0.008. And
the calibration slope specification in Section 4.4.5 has been
changed from 25,800 +_ 600 to 26,000 +_ 780.
While several respondents endorsed the use of transfer
standards in general, one respondent questioned the advisability
of allowing the use of transfer standards based on methods known
to be highly variable even under ideal conditions. EPA still
believes that the variability of such transfer standards will be
adequately controlled by the qualification and certification
requirements on transfer standards described in the transfer
standard Technical Assistance Document mentioned previously.
Hence, EPA has made no major changes to the transfer standard
concept as originally proposed.
In regard to EPA's statement that no factor is available to
"correct" previously collected ozone measurements to make them
comparable to the new UV standard, one respondent thought that
EPA should allow individual states or Regions to make corrections
12
-------
to their previously obtained ozone air quality data if they have
consistent comparative data for the NBKI and UV photometric
calibration techniques. EPA has re-evaluated this position, but
as noted below, still discourages such attempted corrections.
Effect on National Ambient Air Quality Standard for Ozone
Because of the substantial variability of the NBKI procedure
and the unpredictable bias results reported by various investigators,
the exact magnitude of any universal bias which may exist between
the NBKI and UV procedures cannot be determined. However, avail-
able data suggest that any such bias probably does not exceed 10%
on the average. For this reason, EPA believes that supersession
of the NBKI calibration procedure with the UV procedure should
have no effect on the magnitude of the National Ambient Air
Quality Standard for Ozone (being revised elsewhere in this issue
of the FEDERAL REGISTER). And for the same reason, EPA discourages
any attempt to "correct" or "adjust" previously obtained oxidant
or ozone measurements to make them "comparable" to measurements
based on the new UV calibration procedure—even when individual
agencies or laboratories try to determine a more precise, laboratory-
specific bias value.
Effect on Currently Designated Reference and Equivalent Methods
As noted in the June 22 proposal, a change in the calibration
procedure specified in Appendix D of 40 CFR Part 50 does not
13
-------
affect the design or performance characteristics of existing
reference methods for ozone. The only effect of the change is on
the calibration procedure described in the operation manuals
associated with the analyzers. EPA will allow a 6-month period
of time after final promulgation for manufacturers to revise
their manuals, have the revised manuals approved by EPA, and
distribute revised manuals (or manual supplements) to all analyzer
owners.
The two equivalent methods for ozone designated to date pre-
scribe the NBKI calibration procedure. Because the UV calibration
procedure and the transfer standard concept are as beneficial to
equivalent methods as they are for reference methods, EPA will
also request that the manufacturers of the two equivalent methods
revise their respective manuals to specify the UV procedure or
certified transfer standards for calibration. EPA believes that,
under the circumstances, such a modification to equivalent methods
for ozone is desirable and appropriate and should not jeopardize
their designated status. Conversly, failure to make such a
change may be considered by EPA as possible grounds for cancellation
of the equivalent method designation under 40 CFR 53.11. If all
manufacturers respond promptly to this request for appropriate
manual changes, there will be no impact (other than the change in
calibration procedure itself) to owners of designated ozone
analyzers.
14
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Revision Adopted
Accordingly, with the final changes as described above,
Appendix D of 40 CFR Part 50 is revised as set forth below.
Date
Administrator
15
-------
is amended J"
.icnts on the use of transfer standart
\nd on the transfer standard guideliny
re welcome.
JSE or NEW PROCEDURES PRIOR
PROMULGATION OF AMENDMENT
^.indicated in this proposal, th* UV
calibration procedure—and to a ^esser
exten\ the BAKI procedure—ye be-
lieved \to be scientifically superior to
the currently prescribed NBJCI cali-
bration procedure And it is very likely
that the\UV procedure (and the BAKI
procedure^ on a temporary basis) will
be promulgated to supersede the
NBKI procedure. Accordingly, agen-
cies whichXhave the capability and
desire to commence using'these proce-
dures immediately would not be dis-
couraged frorn doing so Immediate
use of transfer\standards could also be
considered on the same basis.
PUBLIC KARTICIPATION
All documents arid information rele-
vant to this rulsmaking are being
placed in Docket iw. OAQPS 78-8, the
docket for the proposed amendments
to the standards fcir photochemical
oxidants. That docneft, will be available
for public inspection during the hours
8.00 to 4.30 at,the PuSilic Information
Reference Unit. Room\ 2922, 401 M
Street SW. Washington.\D.C.
Comments/on any aspect of this pro-
posed amendment are solicited from
interested -persons or agencies. Com-
ments should be submitted to Mr.
Larry J. Purdue at the address given
at the beginning of this nonce. Com-
ments should be receded \ttithm 60
dajs of.-"the date of publicationUor due
consideration prior to final prqrnulga-
tion. Copies of all comments received
will tie added to the docket. \
Ir/addition interested personsynay
ma/ce comments on the proposal otally
at/the public hearing on the oacme
sttmdard scheduled for July 18. 1971
Dated- June 9. 1978.
DOUGLAS COSTLE.
Administrator.
It 10 propc
MM! Part 50 of
Title 40. Code of Federal Regulations
as follows:
1 Appendix D is revised to read as
follows:
APPENDIX D—MEASUREMENT PRINCIPLE AND
CALIBRATION PROCEDURE FOR THE MEASURE-
MENT OF OZONE IN THE ATMOSPHERE
AUTHORITY Section 109 301 of the Clean
Air Aci as amended (42 USC 57409. 7601)
MEASUREMENT PRINCIPLE
1. Ambient air and eihylene are delivered
simultaneously to a mixing zone »here the
ozone in the air reacts with the eihylene to
f:DEHAl REGISTER. VOl. «. NO. 121— THURSDAY, JUNE 22. 1978
Ifi
-------
PROPOSED RULES
3. Apparatus. A complete UV calibration
system consists of an ozone generator, an
output port or manifold, a photometer, an
appropriate source of zero air, and other
components as necessary. The configuration
must provide a stable ozone concentration
at the system output and allow the
ohotometer to accurately assay the output
concentration to the precision specified
for the photometer (3.1). Figure 1 shows
a commonly used configuration and serves
to illustrate the calibration procedure
which follows. Other configurations may
require appropriate variations in the
orocedural steps. All connections...
emit light, which is detected by a photomul-
tiplier tube The resulting photocurrent is
amplified and is either read directly or dis-
played on a recorder
2 An analyzer based on this principle will
be considered a reference method only if it
has been designated as a reference method
in accordance with Part 53 of this cnapter
and calibrated as follows
CALIBRATION PROCEDURE
1 Principle The calibration procedure is
based on the photometric assav of ozone
concentrations in a dynamic flow
system. The concentration of d in an ab-
sorption cell is determined from a measure-
ment of the amount of 254 nm lignt ab-
sorbed b> the sample This determination
requires knowledge of cl) the absorption co-
efficient (u) of Oi at 254 nm. (2) the optical
path length U) through the sample. (3) the
transmittanca. of th,e s,afT?PlC_ j'j__it__jiii>e-_
length of 25'ifim. and U) the'temperature"
(T) and pressure IP) of the sample The
transmictance is defined as the rano I/I,,
where I is the intensity of light which
passes through the cell and is sensed by the
detector when the cell contains an O,
sample, and I, is the intensity of light uhich
passes through the cell and is sensed by the
detector -Alien the cell contains zero air It is
assumed that all conditions of the s>stem.
except for the contents of the absorption
cell, are identical during measurement ot I
and I, The quantities defined above are re-
lated b> the Beer-Lamoeri absorption law.
Trjm-.:tjice « *- • e"lCI '')
3
where
a=absorption coefficient of Oi at 254
nm = 30S=4 atm'1 cm'1 at O'C and 760
torr !>•"«»•«'i = ^
c = d concentration in atmospheres
J=optical path length in cm
In practice, a stable O, generator is used
to produce Oi concentrations o< er the re-
quired range Each Oj concentration is de-
termined from the measurement of the
trsinsmutance (I/I,) of the sample at 254 nm
with a photometer of path length I and cal-
culated irom the equation.
or.
cum • - — (.n II
«;,-,, . . 12- ,,„
"he calculated O, concentrations must be
corrected for O, losses vihich may occur m
the photometer and for the temperature
and presiure of the sample
2 Applicability This proceaure is applica-
ble to the calibration of ambient air d ana-
lyzers, either directly or by means of a
transfer standard certified by this proce-
dure. Transfer standards must meet the re-
quirements and specifications set forth in
References
3 Apparatus I Piaq
tfro nu
calii
"HtuGUiiU.il u UtuiL
(space)
(0 [zero])
afcste
connections between
17
FEDERAL REGISTER. VOL 43, NO. 121—THURSDAY, JUNE 22. 1978
-------
26975
glass, Teflon, or other n
relatively inert materials.!
Devices capable of regulating
air flows as necessary to
meet the output stability
and photometer precision
requirements.
components in the calibration system down-
stream of the O. generator should be of
^^^Additional informa-
tion regarding the assembly of a UV photo-
met nc calibration apparatus is given m Ref-
erence 9 For certification of transfer stand-
ards which provide their own source of O,.
the transfer standard may replace the O,
generator and possibly other components
shown in Figure 1. see Reference 8 for guid-
ance.
3 1 tTV photometer. The photometer con-
sists of a low-pressure mercury discharge
lamp, (optional) collimation optics, an ab-
sorption cell, a detector, and signal-process-
ing electronics, as illustrated in Figure 1 It
must be capable of measuring the transmit-
tance. I/Io. at a wavelength of 254 nm with
sufficient precision such that the standard
deviation of the concentration measure-
ments does not exceed the greater of 0 005
ppm or 3% of the concentration Because
the low-pressure mercury lamp radiates at
several wavelengths, the photometer must
incorporate suitable means to assure 11.ai.
no Oi is generated m the cell by the lamp.
and that at lease 995% of the radiation
sensed by the detector is 254 nm radiation
(This can be readily achieved by prudent se-
lection of optical filter and detector re-
sponse characteristics > The length of the
light path through the absorption cell must
be known with an accuracy of at least
99 5% In addition, the cell and associated
plumbing must be designed to minimize loss
of O> from contact witn cell walls and gas
handling components See Reference 9 for
additional information.
3.2 Air flow controllers. Doviooo capable of
- maintaining oonotant air flow within -!_ac"u
3.3 Ozone generator. Device capable of
generating stable levels of Oi over the re-
quired concentration range
3 4 Output manifold. The output manifold
should be constructed of glass. Teflon*"or (delete "R")
other relatively inert material, and should
be of sufficent diameter to insure a negligi-
ble pressure drop at the photometer connec-
tion and other output ports. The system
must have a vent designed 10 insure atmos-
pheric pressure in the manifold and to pre-
vent ambient air from entering the mani-
fold.
3 5 Two-way valve. Manual or automatic
valve, or other means to switch the photom-
eter flow between zero air and the O, con-
centration.
3 6 Temperature indicator Accurate to
±rc.
3.7 Barometer or pressure indicator. Accu-
rate to = 2 torr.
4. Reagents.
4 1 Zero air The zero air must be free of
contaminants which would cause a detect-
able response from the O, analyzer, and it
should be free of NO. C,H.. and other spe-
cies which react with O,. A procedure for
generating suitable zero air is given in Ret- , .
erence 9. As shown m figure 1. the zero air ( r )
supplied to the photometer cell for the I,
reference measurement must be derived
from the same source as the zero air used
for generation of the ozone concentration to
be assayed (I measurement). When using
the photometer to certny a transfer stand-
ard having its own source of ozone, see Ref-
erence 8 for guidance on meeting this re-
quirement.
18
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26976
5 Procedure
5 1 General operation The calibration
photometer must be dedicated exclusively
to use as a calibration standard It should
alwavs be used with clean, filtered calibra-
tion gases and never used for ambient air
sampling Consideration should oe guen to
locntir.g the calibianon photometer in a
Cit?an laboratory where it can be stationary
protected irom ph>sical shock, operated b>
a responsible analyst and used as a common
^iandara for £11 field calibrations via trans-
fer standards
5 2 Preparation Proper operation of the
photometer is of critical importance to the
accuracy of this procedure The following
hieps uill help to verify proper ope-anon
The, stops are not necessarily required prior
to each use of the photometer Upon initial
operation of the photometer, these steps
s.iould be earned out frequently, with all
quantitative results or indications recorded
m a chronological record either in tabular
form or plotted on a graphical chart As the
performance and stability record of the
photometer is established, the frequency of
these steps may be reduced consistent with
the documented stability of the photometer
521 Instruction manual. Carry out all set
up and adjustment procedures or checks as
described in the operation or instruction.
manual associated with the photometer
522 Sjstem check Check the photometer
s>si.em for integrity leaks, cleanliness.
proper flow rates, etc Service or replace fil-
ters and rero air scrubbers or other consum-
able materials, as necessary
523 Linenrit\ *~-i Ten rhn photomutcr
fop linearity n' dilution Generate and assay
an O, concentration near the upper range
1'mit of the sv&tem (0 5 or 1 0 ppm) then ac-
curatelv dilute that concentration vvtth zero
air and reas;>a\ it Repeat at several difter-
ciu dilution ratios Compare the assav of
the ong'nal concentration with the assay of
the diluted concentration divided bv the di-
lution ratio, as follows
5.2.3. Linearity: Verify that the
photometer manufacturer has adequately
established that the linearity error
of the photometer is less than 3%, or
test the linearity by dilution as
follows: Generate ...
where
E = !meaniv error percent
A,=asiav 01 the onginal concentration
A.=nssav of the diluted concentration
R-dilution ratio = flovv of original concen-
trai.on divided bv the total flow
Tr-e linearitv. error rmist be less than 5<^
Since the accuracy of the measured flow-
rates »ill affect the linearity error as meas-
ured this wav the test is not necessarily
conclusive Additional information on ven-
fMng linearity is contained in Reference 9
524 Intercompanson When possible.
the photomerer should be occasionally m-
te'compared either directIv or via transfer
standards 'viih calibration photometers
used bv ether agencies or laboratories
525 Ozone losses Some portion of the
O, mav be lost upon contact with the pho-
tome'.er cell walls and Jfas Handling compo-
r.ems The magnitude of this loss must be
drterrninea and used to correct the calculat-
ea O, concentration This loss must not
Q\cvsd 5"^ Some guidel'nes for quar.lita-
iivrl; de!er-rinmg this "oss are discussed in
Reference 9
--(g)
19
-------
PROPOSED RULES
allows
Insure thatj-
Insure thatj-
5 3 Assay of O, concentrations.
5 3 1 Allow the photometer system to
warm up and stabilize
532 AdjttsiJJthe floArate through the
photometer absorption cell. F.. to ft oonio-
rioni . dluo r,o ifratfthe ceil eett^be flushed in
a reasonably shoiO period of 'time (2 luer/
mm is a typical flow.) The precision of the
measurements is inversely related to the
time required for flushing, since the pho-
tometer drift error increases with time
533 Atljuot'the flow rate into the output
manifold to a value-at least 1 liter/mm
greater than the toLar flowrate required by
the photometer and any other flow demand
connected to the manifold
534 Adjast^the flow rate of zero air Pz.
te a valgT.at least 1 liter/nr.m greater than
trip flow rate required by the photometer
535 With zero air flowing m the output
manifold, actuate the two-way valve to
allow the photometer to sample first the
manifold zero air. then P, The two photom-
eter readings must be equal (I=I0)
NOTE In some commercially available
photometers, the operation of the two-way
\alve and various other operations in sec-
tion 5 3 ma> be carried out automatically by
the photometer
536 Adjust the O, generator to produce
an O, concentration as needed
537 Actuate the two-wav valve to allow
the photometer to sample zero air until the
absorption cell is thoroughly flushed, and
'record the stable measured value of I,
538 Actuate the two-way valve to allow
the photometer to sample the ozone concen-
tration until the absorption cell is thor-
oughly flushed and record the stable meas-
ured value of I.
539 Record the temperature and pres-
sure of the sample in the photometer ab-
sorption cell. (See Reference 9 for guid-
ance )
5 3 10 Calculate the O, concentration
from equation 4 An average of several de-
terminations mil provide better precision.
-[Verify that
-fro
"j OUT
'.TT-
where
tOJoLT = Oj concentration ppm
a = absorption coefficient of Oi at 254
nm = 308 atmr1 cm'1 at O'C and 7SO torr
/=optical path length, cm
T = sample temperature. K
P=sample pressure, torr
L=correction factor for Oj losses from
5 25=(l-fraction O, lostJQ *
Note —Some commercial photometers
may automatically evaluate all <&y part of
equation 4 It is the operator's responsibility
to verify that all of the information re-
quired for equation 4 is obtained, either
automatically by the photometer or man-
ually For •automatic* photometers which
evaluate the first term of equation •) based
on a linear approximation a manual correc-
tion may be required particularly at higher
O, levels See the photometer instruction
manual and Reference 9 for guidance
5311 Obtain additional O, concentration
standards as necessary by repeating steps
5 3 6 to 5 3 10 or by Option 1
(or)
20
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5 4 Certification of transfer standards A
transfer standard is certified b;, relating the
output of the transfer standard to one or
more ozone standaids as determined accord-
ing to section 5 3. The exact procedure
varies depending on the nature and design
of the transfer standard Consult Reierence
8 for guidance
5 5 Calibration of ozone anahzers. Ozone
anal}zers are calibrated M foiious using
. . 71 • analjzers are calibrated as foiinus
Certified ^ ozone standards obininpd'ficcornmg
-I ' tion 5 3 or b> means ofHransfer stand
to see-
... transfer standard* i^^^^^^
551 Allow sufficient lime for the O, ana- —(delete "s")
lyzer and the photometer or transfer stand-
ard to warmup and stabilize
552 Allow the O, anal\?e) to sample
zero air until a stable response is obtained
and adjust (he Oi analjzers zero control.
Offsetting the analyzer s zero adjustment to
-o^c of scale is recommenoed to lacihtate
observing negative zero drift Record the
stable zero air response an ' Z"
553 Generate an O, concentration
standard of approximately 80"~i of the de-
sired upper range limit (URL) of the O, ana-
lyzer Allow the O, analv^cr to sample this
O, concentration standard until a stable re-
sponse is ootained
554 Adjust the O. annlvzers span con-
trol to obta.n a convenient recorder re-
sponse as indicated below
w here
URL=upper range limit of the O, analyz-
er ppm
Z=recorder response with zero air *~t scale
Record the O, concentration and the cor-
responding analyzer response If substantial
adjustment of the span control is necessary
recheck the zero and span adjustment by
repeating steps 5 5 2 r.o 5 5 4
555 Generate several other Oj concen-
tration standards (at least 5 others are rcc
ommended) over the scale range of the O,
analyzer by adjusting the O, source or by
Option 1 For each O, concentration stand-
ard, record the O, concentration and the
corresponding analjzer response
5.5 6 Plot the O, analjzer responses
versus the corresponding O, concentrations
and draw the Oi analjzcr s calibration curve
or calculate the appropriate response factor
557 Option ; The various O, concentra-
tions required in steps 5311 and 555 may
be obtained oy dilution of the Oi concentra-
tion generated in steps 536 and 553 With
this option, accurate flow measurements are
required. The djnamic calioration svstem
modified as shown in Figure 2 to
aliow for dilution air to be metcred in down-
stream of the O, generator A miMng cham-
ber between the Oi generator and me
output manifold is also required The flow
rate through the O, generator tF,,J and the
dilution air flow rate (Fn) are measured with
a reliable flow or volume standard traceable
to NBS Eacn d concentration generated bv
dilution is calculated from
« here
21
-------
PROPOSED RULES
CO 1 m T=diliuen the Gas Phase.
1 Rate Constant ind Actuation Sner^-es".
Int : Jour at Chcin. Kinetics, VI. 725 (19745
6 M A A Cl) ne ana J A Co\om. Kinet-
ic Studies of O\y halogen Radical Systems".
Proc. Roy Soc. A303 207 (1968)
/ ,
v_
(7)
J Pajr. H A
'-
w Trr-
\ I Tl-e U.t-aviole: Spectrun
. J9. i:>03 1 1973)
26977
.
Photoly.
J C»iewi
(delete "in
draft form)
8 'Transfer Stnr.cards for Calinration of
Ambient Air Mor.itonng Analjzers for
Ozone EPA_ Publication a'anaole
»nn irom tPA. Department E
Researcii Triangle Park XC 27711.
— 1f-P-i"!-^-3S-Sta"CM Doc'-!f:'6nt f"j"
EPA P.io!icatiop. •" "•li':["'
fro-. EPA. Department E
Research Tnanale Pa.-,:, X C J7711.
rCalibration of Ambient Ozone
illonitors",
(77)
22
-------
PROPOSED RULES
ZERO
AIR
now
CONTROLLER
FO
°J
GcncRAtoR
I FLOW
CONTROLLER
r
UV PHOTOMETER
Sic.'iai
PROCESSING
ELCCTHOrjICS
OUTPUT
MANIFOLD
• VEKT
VtUT
1.1
EXTRA OUTLETSC&PPEO
WHEN NOT IN USE
T3I11ETOF ANALVZER
U.'.DEP C4LI8RATIO'J
OfCS
ABSORPTION CELL
DSOUPCE
0
• EXHAUST
Figure 1 Sc'iemaiic I'lugram ol 3 lypicjl OV i>i.oiomt rn. Cu-iuicuoi. S.SK.'".
EXTRA OUIitTSripC
V.HEN -JOl I'J USE
• VEM
F.nu-e ? Sc'-.c-'anc diagram of J i.pieal 'JV onc'o—? • c c: -'"afon :vs ,-m "OPT:;:1" :i
FEDERAL REGISTER, VOL. 43, NO. 121—THURSDAY, JUNE 22, 1978
23
-------
Ozone is absorbed in a 0 1M l~" _
.so.) soiution containing i% reacts with excess iodide ion (I ) to form triiodide
e It released<• is measured !,•«« /T~\ , ,u-;^u
netncally u ii»o Hmauntu .urn I10n U-j) WhlCP ...
Terr.pc'ary Alternative Calibration Proce-
dure— 13onc Acia-Potassurn Icaide) This
procecvire .T&J oe used as an alternative to
il-e u;t~v.olet Photometry procedure for
d.rect cal.ora: on of ozone analyzers—but
r.ot to cer: fv r.-ar.sfer stanoaros—until C18
rr.cri'-.s a::er the date of final promulga-
tion! Alter that time tms procedure can be
used or.lj as a transfer standard in accord-
ance with the guioar.ce and speculations
set form in Reference 4. 'Transfer Stand-
ards for Calibration of Ambient Air Moni-
toring Analir.ers for O:o".e '
1. Pr nciple This calibration procedure (1)
is oased upon the reaction between ozone
(O:) anc potassium looiae (KI) to release
locme cl:j according to the stoichiometnc
equation (2)
The stoichior-.e:ry is such that the amount
of I: released is equivalent to the amount of
Oi absoroed Ozone is absorbed in a 0 1M
boric acid 'H,
KI. and the
spectropnotomet really
<*^at a «a<.elt-rlg:h of 352 nrr The output*
of a stable O, .rene-ator is assayed sn r'lis
manner, ana -"e generator is immediately
used :o calibrate the Oi analvzer The Oi
generator mjal be used immediately alter
calibration ana Aithout p'ljsical movement.
and it is -ecahoraied prior to each use Al-
terrat.vely U-.e Oi inaljzer may be calibrat-
ed by assaiir.2 tne Oi concentrations using
the preserved procecure vvniie simulta-
neously measuring the corresponding O,
analyzer responses Ozone concentration
stancaras mnjr also be generated by an op-
tional ciluuon technique With this option.
the lug.-ipst Oi concentration standard is as-
saied using the prescnoed procedure The
aad.uonai O. concentration standards re-
quired are then obtained b> dil.ition
2 Apparatus Figures 1 and 2 illustrate a
t.vpical 3AKI O, calibration bjstem and
SP.OA the sj-'scsted configuration of the
components Ustsd oelovv All connections be-
tween co-naopeits downstream of the O,
gi-::erator jr.oula be of glass. Tcflonf ^ or
ot ler relati.e'j mer: material.
2 1 Air no\\ controller Device capable of
maniiainm): a co:iotam air ilowrate thiough
trie Oi iii'ner.iior >vitnm =2^1
22 Air ilo" meter Calibrated flov.meter
capaole o! mcasunng and monitontig the
air ilC'vratc tnrough the O, generator
within =Jrl
23 Ozor.e gcrierator Device capable of
gem'raiT.e stable le-.els of Oj over the re-
qicred concentration range
J •{ O'Jtpi:: manifold The output mnni-_
folj inou 3 be co:-s:ruc:ea of glass. Teflon^'i
or o:!'er reMi. eiv inert material and should
be o: 3uific:c.T. oiarnete- to Tisure an negli-
gible pressure croo r.t fie anaijzcr connec-
tior. Tl-p i;.item "iij-.t nave a vent des.ened
to insure a'r-.osonor'c pressure m the rnnni-
fola and to pre ent arr.oieru air from enter-
ing ti:e rRiinifoU
J 5 Irr.pir.gc-rs All glass impirgers with
the speciiicit ons ird.cated 'n F'guie 2 are
recorrmoideo T.:c irr.o'rigcrs r"3> be pur-
chas^ii irom i-.ost major 2l.iss.>a:e -supp.:-
ers T vo 'mp'rjers connected in series are
usoa to ir.iure compete collection of the
2 ri Air puri-ip and floa controlior Any
pump a:-.ti flo" co:itrol de1 ice capaole of
f.a!n;.-'i!''-is: .1 constant f'o-vrate of 04-06
liter, mm throiu'M the impmsers may be
iiacd A <.rii>cal orifice as described by Lodge
Xdelete "as the triiodide ion (13))
-(delete "R")
•(delete "R")
FEDERAL REGISTER. VOL. 43, NO. 121— THURSDAY. JUNE 22. 1978
24
-------
PROPOSED RULES
500, ]-
et al (3) is recommended The orifice should
be protected against moisture and panicu-
late matter with a mem crane filter or mois-
ture trap containing Dnente/Xsilica gel. or
glass wool The air pump must be capaole of
maintaining a pressure differential of at
least 0 6-0 7 atmospheres across the critical
orifice Alternatively, a needle valve could
be used with the pump to adjust the flow
through the impingers. A floumeter is then
recommended to monitor the flow The
neeoTe valve-floumeter combination should
be protected against moisture and panicu-
late matter with a membrane filter or mois-
ture trap
2.7 Thermometer Accurate to = 1'C.
2 8 Barometer. Accurate to =2 torr
29 Volumetric flasks (Class A) 25. 100.
_2,0q*1000.ml £
2TO Pipets (Class A) I././ 5. 10. 15. 20,
and 25-ml volumetric^ (•
2 11 Spectrometer Capable of measuring
absorbance at 352 nm with an absolute accu-
racy of =!<"<> and linear response over the
range of 0-1 0 aosorbance units The photo-
metric accuracy may oe checked using opti-
cal glass filters which have certified absor-
ba.ice values at specified wavelengths.
Matched 1-cir. or 2-cm cells should be used
for all absoroance determinations
3 Reagents
3 1 Zero air The zero air must be free of
contaminants vvrucn Will cause a detectable
response on the Oi anaivzer or which might
react with 1% BAKI Air meeting this re-
quirement may be obtained by (1) passing it
through silica gel for drying: (2) treating it
with Oj to comert any nitric oxide (NO) to
nitrogen dioxide (NO:). <3> passing it
through activated charcoal (6-14 mesh) and
molecular sieve (6-16 mesh, type 4A> to
remove any NO,, hydrocaroons. and traces
of water < apor. and '4) passing ic through a
2-micron filter to remove any paniculate
matter
3 2 Boric acid (K.BOJ ACS reagent grade
33 Potassium iodide (XI). ACS reagent
grade
34 Kvdrogen pe-oxide iH,O,). ACS rea-
gent grade. Zf0 or 30~
3.5 Potassium lodate (KIO,). ACS reagent
graae certified 0 IN
36 Suliunc acid . ACS reagent
grade. 35aa to SS1^
37 Distilled v.ater Used for preparation
of ->il reagents
3 8 Absorbing reagent Dissolve 6 2 g of
bone acid
-------
26979
jsing a
graduated
pi pet, add
D.7
absorbance units/cm g-eaier :han the first
deierrr.ip.at.on. the acsorb.ng reagent 15
reaay for "s* Jf_ no increase or an increase
of .ess thanpHHO absorbance un.:s/cn is oo-
ser\ ed. the KI reagent probaoly contains an
excessive amount of a reducing contaminant
and must oe disca.ra.ed In this event pre-
pare fresh absorbing reagent using a differ-
ent numbered lot 01 KI If unacceptable ab-
sorbing reagent results from cifferert lots
of KI. test the possibility of contain.nation
in the HiBO, by using a different numbered
lot of H.BO, -
3 9 H>drogen peroxide solut:onVfl,an»'-.i
Tiliii» il'iTil of 30«c o&JW ir.l of 3«". hydrogen
peroxide (H,O,) >eto approximately 200 ml
of distilled wateriTfa'-BgBSaL volumetric
flask, dilute to volume with dist
and mix thoroughly To prepare the
c, -i aiOOt8"iflSOlmion. ciastrt ml of the aooxe so-
">j lulion into 50 ml of distilled water in a 100-
ml volumetric flasK. d.lute to voiume vv.h
-, distilled water, and mix thorough'.! This
U . UL)£ I ,a I L Q.OQiarj»H.O, solution must be prepared
fresh eacn time a fresh catch of absorbing
reagent is prepared Therefore tne renam-
ing contents of both volurretnc flasks
should be discardec after treatment of tlie
BAKI aosoroir.g reagent (see 3 3)
3 10 Standard potassium iCdtite solution
(0 IN) Use a commercial standard solution
of potassium lodate iKIOi) ha< ing a certi
fied normality
311 Suifunc acid (1>7) D-lute 23 ml of
concentrated (95-98"^) sulfunc acid fH.SO.)
to volume in a 1000-ml voiunetnc flask
4 Procedure.
4 1 Assemble an ozone ca!ibra:.on system
such as sho
Ts = temperature at sarr.plinc concslions
'C
44 KI calibration cur1, e
4 4 1 Prepare iodine standards fresh
when nceucd as follow s
A Accurate^ pippt 10 ml of 0 IN standr.rd
poiaumm lodaie 'KIO.i solution 'nto a iOl>-
ml volumetric tlask containiiiR approximate
Ij 50 ml of distilled vater Ada 1 g of poiis
sium iodide (KI) and 5 ml of IN siilfunc
-------
26980
acid (H.SO.). dilute to volume with distilled
water and mix thoroughly
B Irrmeoiate'v- before use. cipet 10 ml of
Hie 'Odme (L) solution prepared in steo A
above into a 100-ml volumetric flask and
dilute to volume with absoromg reagent.
Then further dilute this solution by pioet-
tms 10 ml of 11 into a 200-ml volumetric
flask and diluting it to volume with absorb-
ing reagent
C. In turn pipet 5. 10. 15. 20 and 25 ml
aliquots of the final I, solution prepared in
step B above into a series of 25-ml voljmet-
ric flasks Dilute each to volume with ab-
sorbing reagent and mix thoroughly To
prevent Ii losses by volatilization, tne flasks
should remain stoppered unil absorbance
measurements are made Absorbance mea-
surements (see 442) should be taken within
CO minutes after preparation of the I, stand-
ards
4 4 J Determine the absorbance of each
I.- standard at 352 nm. Also measure the ab-
sorbance of a sample of unexposed absorb-
irg reagent Determine the net absorbance
of each I, standard as.
443 For each I, standard, calculate the
net absortance/cm as
D=spectrophotometer ceil path length cm
444 For each I, standard calculate the
I. concentration in mc'.c/ liter as
or.
\\jiere
(5b)
CI.],=concentranon of each I, standard.
mole I,/!!ter
t% of KIO, (from 3
hter
V, = volune of I, solution (from step
4 4 1 C) = 5. 10. 15 20 or 25 ml
445 Plot net absorbance/cm (y-axis)
versus tne mole I;/'lner (\-axis) for each I,
Standard and drau the KI calioration curve
Calculate the slope of the ome in liter
•nole"' cm" and record as S, The value of
the slope should b
-------
PROPOSED RULES
4 5 Calioration of the ozone generator
451 Adjust the air flow through the O,
generator to the desired llOArate and record
as FJ At all times the air flow througn the
generator must be greater than the toial
flow, required bj the sampling ijsierr.s. to
assure exhaust flou at ihe vent
452 With the O, generator off. flush the
system 'vith zero air for at least 15 minutes
to remove residual O, Pipet 10 ml of absorb-
ing reagent mio each of 2 imomsers and
connect them into the sampling train as
shown in Figure 2 Draw air from the
output manifold of the O, calibration
svsterr. through the sampling train at 0 4-
0 6 liter/mm for 10 minutes Immediately
transfer the exposed solution-; to clean spec-
trophotometer cells Determine the pet ao-
soroance (sample absortar.ce-unex?os?d
reagent absoruance) cf eacn solution at 352
nm within three minutes And the net ab-
sor'cnnces of the two solutions to obtain the
total net abscrbance Calculite the muicat-
ed Oi concentrat on is.vstem oiank) as equiv-
alent. O, concentration according to 4 5 4 If
the sjstem blank is greater than 0 005 ppm
O>. continue fljs.-img trie O, generation
s> stem for an additional 30 minutes and re-
asterrr.ine the s;.s;em blank If tne svstem
blanii is still greater than 0 COS ppm O, the
zero air prooaoly contains traces of an oxi-
d.zir.g contarr..r-ant. a^.d the activated cnar-
coa! ana mclscj.ar sieve (see 31) snould be
reo'aced
453 Adjust the Oi generator to generate
an Oj concentration in the range cf interest
and a..ou. i,-.a sj.stsm to equilicrate for
aoout 15 minutes The uncaliorated O, ana-
lyzer to oe cal arat?d can corr.emencly be
used to indicate trie stiiotl.ty of the O, gen-
erator output Wren i'.:e d generator
ou:pjt has stabilized, pipec 10 ml of aosorb-
ir.g rsageni ir.to each impinger Draw. O,
from tr.e output mar.iicid cf the O, calibra-
tion system t.-.rci-g.i the sampling train at
04-06 l:tcr/rr..n Use a sample time of be-
tween 10 and 33 minutes such that a total
net a^ssroar.cs between 0 1 and 1 0 absor-
oar.ce uni;s is cbta'nsd (At an O, concentra-
tion cf 0 1 ppm and a sampling rate of 0 5
!iter/T.in, a total net absorbance >0 1 absor-
tance s.r".s sr.ould os co:a:ned if a sampling
time of 20 rr.ir..:tes and l-cr»i scec:ropnoto-
rr.ster cells are ussa ) Immeciately after col-
lection transfer the exposed solutions to
clean spsctrcphoiometsr cells Determine
the net absoroance (sample absorbancs—im-
c\posed reagent aosorbance) of each solu-
tion at 352 nm Kithin three minutes Add
the net absorbances of the two solutions to
obtain the total net absorbance
454 Calculation of ozone concentration
4541 Calculate the total \olume of air
sampled cor-ected to reference conditions
of 25 C and T60 torr as
4542 Calculate the I, released in moles
as.
w here
VB = volume of air sampled, corrected to
reference conditions liier
F» = sampling flovvnto corrected to refer-
ence conditions liter/mm
resampling time mm
.,. .
'
where total net aosorbnnce = sum of net ab-
sorbances for the tuo solutions
001=voiume of absorbing leagent m each
impingcr. liter
Se=sio^: of KI cali'craLion carve liter
mo!c "' cm "'
b = spectrophotomet?r ceil patn length cm
4543 Calculate HIP u/ of O, absorbed as
or.
^/Oj = mole I.\24 -i
4544 Calculate the O. conceniration in
ppm as
455 Repeat steps 453 an d 4 5 4 at least
one more time at the same O, generator set-
ting Average tne I-AO of the O, analvzer
464 Allow the Oi anahzer to sample
this O, concentration until n stable response
is obtained Adjust the anal.vzer's bpan con-
trol to obtain a convenient recorder re-
sponse as indicated below
loir " ° concept-?tion at the output mani-
fold ppm URL = upper range limit of
the O, anal\zer ppm Z = recoraer re-
sponse v.uh zero air "e scale
28
-------
PROPOSED RULES
Record the Oi corcertration and the O»
an.ilizer response If substantial adjustment
of the span control is necessarj. reeheck the
zero and span adjustments by repealing
steps 462 through 464
4 S3 Generate several other O. concen-
trations s also re-
quired The flow-rate through the O, gcr.tr-
ator
are measured with a reliable flow, or '. oluine
standard traceable Co NBS The highest O,
concentration stanaard required ' assaj mg the
-------
26981
O, concentrations using the procedure in 4 5
while simultaneously measuring the corre-
sponding O, analyzer responses as specified
in 46.
REFERENCES
1 D L. Plamm. "Analysis of Ozone it Loi
Concentrations with Bone Acid Buffered
KI." Environ. Sci. fechnol. 11. 978 (1977).
2 B E Saltzman and N Gilbert. "lodome-
trie Microdeterrrunation of Organic Oxi-
dants and Ozone." Anal Chem.. 32, 1914
(1959).
3. J. P Lodge. Jr. J B. Pate. B E.
Ammons, and G A Svianson. "The Use of
Hypodermic Needles as Critical Orifices in
Air Sampling." J Air Poll Control Assoc..
16. 197(1966)
4 "Transfer Standards for Calibration of
Ambient Air Monitoring Analizers for . , „ . , _. ,. „
Ozone.' EPA Publication available «-****<——( delete 1 H draft TOrm
form from EPA. Department E lMD-7<).
Research Triangle Park. N.C 27711.
30
-------
26982 .
PROPOSED RULES
O'
ZERO
AIR
FLOW
CONTROLLER
FLOV.'METER
F° .
03
GENERATOR
OUTPUT
MANIFOLD
VENT
EXTRA OUHETSCAPPEO
U'HEiM NOT IN USE
TO ITJLETOF
Kl SAMPLING TRAIN
i
TO ff'RET OF ANALYZER
UWOER CALIBRATION
Fujuro 1 Sclu'iiutic
o! ;i t/.nc.-l SAKi c^ i'.nuiion
31
FEDERAL REGISTER. VOL. 43. NO. 121—THURSDAY, JUNE 22. 1978
-------
PROPOSED RUL2S
26983
HYPODERMIC
NEEDLE
TO AIR
PUMP
CRITICAL ORIFICE FLOW CONTROL
INSIDE
CLEARANCE
3 TO 5 mm
jL
10 mm O.D.
24 40, CONCENTRIC WITH
OUTER PIECE APJD WITH
NOZZLE
GRADUATIONS AT 5-ml
INTERVALS. ALLTHE
WAY AROUND
NOZZLE ID. EXACTLY
1mm: PASSES 0.09 TO 0.11
cfm AT 1Z m H20 VACUUM.
PIECES SHOULD BE INTER-
CHANGEABLE,MAINTAINING
NOZZLE CENTERING AND
CLEARANCE TO BOTTOM
INSIDE SURFACE
GLASS
WOOL ,$£&,
'
TRAP
A
f [\l/1 ^ TO AIR
f f l/Nl PUMP
NEEDLE VALVE
I
FLOWMETER
ALTERNATE FLOW CONTROL
ALL GLASS MIDGET IMPINGER (THIS IS A COMMERCIALLY
STOCKED ITEM).
Figure 2. Kl sampling tram.
32
FEDERAL REGISTER, VOl. 43, NO. 121—THURSDAY, JUNE 27, 1978
-------
26984
PROPOSED RULES
03
GENERATOR
Mi XING
CHAMBER
VENT •*
OUTPUT
MANIFOLD
EXTRA OUTLETS CAPPED
WHEN NOT IN USE
Ill
I
t
TO INLET OF
Kl SAMPLING TRAIN
TO INLET OF ANALYZER
UNDER CALIBRATION
FKRIII- 3 Sc:i"i'\ntu; dunum of <.< ;vP'C.il BAKI cai'iirjtiOfi sysiL'iii (O.)iio;i 1)
[FR Doc 78-17154 Filed 6-21-78 8 -S5 am]
33
FEDERAL REGISTER, VOL. 43. NO 121—THURSDAY, JUNE 22. 1978
-------
TAB C
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON. D C 20460
OFFICE OF
AIR AND WASTE MANAGEMENT
SUBJECT: Amendments to 40 CFR Part 51, Concerning Photochemical
Oxidants—ACTION MEMORANDUM
FROM: David G. Hawkins, Assistant Administrator Environmsniai
for Air, Noise, and Radiation -
Proteo.,0,-,
MEMO TO: The Administrator r >-;,
THRU: AX
LIBRARY
Purpose
The accompanying Federal Register notice amends Part 51 in Title 40
of the Code of Federal Regulations with respect to photochemical oxidants.
A separate action involving 40 CFR Part 50 includes the redesignation of
the photochemical oxidant standard as an ozone standard. Therefore, in
the action accompanying this memorandum, the appropriate nomenclature
changes are being made. A copy of the entire Part 51, underlining the
terms "photochemical oxidants" and "oxidants," is being sent to the
Office of the Federal Register so that these terms can be changed to
read "ozone."
Another part of the accompanying action is the deletion of Appendix
J of 40 CFR Part 51. The deletion is necessary because the modeling
technique described by Appendix J is no longer recommended as the sole
acceptable technique for determining the relationship between ambient
ozone concentrations and hydrocarbon emissions. Part 51.14 is being
amended to account for the deletion of Appendix J and to allow States to
use any of four analytical techniques which include consideration of
background concentrations and levels resulting from ozone transport.
EPA guidance is available to assist States in applying any of the four
techniques.
Major Issues
The deletion of Appendix J was unanimously supported by those
commenters responding to the June 22 proposed action. The use of the
four alternative techniques, however, represents a problem in that
different levels of control could result from one State to another,
depending upon the specific model employed. EPA has responded to this
problem by requiring that States apply RACT regulations on large hydro-
carbon sources when any of the models except a photochemical dispersion
-------
model is used to demonstrate attainment of the ozone standard. In.
consequence, States desiring to demonstrate attainment of the ozone
standard without the application of RACT regulations must do so only by
using a photochemical dispersion model to predict the level of control
needed.
Impact and Anticipated Reactions
States have received notice of the possibility of revisions to the
ozone standard and to the techniques available to develop their ozone
control strategies. Some States have claimed, however, that if the
amendments are not made sufficiently prior to the January 1, 1979,
submittal date for SIP revisions, then an extension will be needed. EPA
is taking the position that the States must submit their ozone plan
(likely to be based on the old standard of 0.08 p.p.m.) on January 1, 1979,
as originally required. States may then make further revisions to take
into account the revised standard at any point thereafter that they
choose. It is anticipated that the States will comply with this ruling
in order to avoid possible sanctions set forth under the Clean Air Act.
Coordination
This action was coordinated with OGC.
Recommendation
I recommend that you sign the enclosed Federal Register notice of
final rulemaking.
Enclosure
-------
Title 40—Protection of Environment
CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY
PART 51—PREPARATION, ADOPTION, AND SUBMITTAL
OF IMPLEMENTATION PLANS
Revisions to Procedures Related to Photochemical
Oxidants (Ozone)
AGENCY: Environmental Protection Agency.
ACTION: Final Rulemaking.
SUMMARY: In this action, the Administrator revises the procedures for
preparation of State Implementation Plans for ozone (formerly photo-
chemical oxidants). Throughout 40 CFR Part 51, the terms "photochemical
oxidant(s)," and "oxidant(s)" are changed to "ozone" to be consistent
with EPA's redesignation of the photochemical oxidant standard as an
ozone standard. The redesignation action is being taken elsewhere in
this issue of the FEDERAL REGISTER.
40 CFR 51.14 is amended to allow States to use any of four analyt-
ical relationships for determining the hydrocarbon reductions necessary
to meet the ozone standard. This particular amendment also involves the
deletion of Appendix J and section 51.14(c)(4).
EFFECTIVE DATE: This rulemaking is effective upon publication.
ADDRESSES: U.S. Environmental Protection Agency, Office of Air Quality
Planning and Standards, Control Programs Development Division (MD 15),
Research Triangle Park, North Carolina 27711.
FOR FURTHER INFORMATION CONTACT: Joseph Sableski, Chief, Plans Guidelines
Section, at the above address or at 919-541-5437 (commercial) or
629-5437 (FTS).
-------
SUPPLEMENTARY INFORMATION
1. BACKGROUND
On June 22, 1978, at 43 FR 26985, EPA proposed certain revisions to
40 CFR Part 51 concerning the procedures for preparation of State Imple-
mentation Plans for photochemical oxidants. This proposed action was
taken simultaneously with related EPA proposals in the same issue of the
FEDERAL REGISTER to numerically change the primary photochemical oxidant
standard from 0.08 p.p.m. to 0.10 p.p.m., to redesignate the primary and
secondary standards as ozone standards, and to change to standards with
a statistical form rather than a deterministic form (43 FR 26962); and
to replace the existing calibration procedure for the ozone reference
methods (43 FR 26971).
A total of four public hearings were held during July and August to
receive comments on all the actions being taken relative to photochemical
oxidants (ozone). In addition, written comments were received through
October 16. EPA received comments on the proposed revisions to the
implementation requirements from 23 commenters, including nine representa-
tives from industry, 10 from State and local governmental agencies, and
four from citizen's organizations and private citizens.
2. SUMMARY OF COMMENTS AND RESPONSES
The following discussion summarizes the comments received on the
proposal to amend 40 CFR Part 51. In some cases, similar comments are
considered together in order to prepare a common response where appro-
priate. Where an interested person wishes to identify individual
comments, a summary of all comments received, including those comments
pertaining to the other related actions, and EPA's responses is available
-------
for public inspection during normal business hours in EPA's Public
Information Reference Unit (PM 215), 401 M Street, S.W., Washington,
D.C. 20460, telephone: 202-755-0707.
2.1 CONTROL STRATEGY
In proposing the deletion of Appendix J, EPA also proposed that
States use instead any of four analytical techniques to determine the
amount of hydrocarbon reductions necessary to demonstrate attainment of
the national ozone standard. The four techniques include: (1) Photo-
chemical dispersion models, (2) Empirical Kinetics Modeling Approach
(EKMA), (3) Empirical and Statistical Models, and (4) Proportional
Rollback.
Several commenters criticized the analytical techniques proposed to
replace Appendix J, citing various shortcomings of the techniques. Some
commenters pointed to the failure of the EKMA and rollback techniques to
account for temporal and spatial distributions of sources in the design
of control strategies and pointed out that, since control of industrial
sources will be extremely costly, the most effective models should be
used in strategy development. One commenter indicated that the level of
control necessary to achieve the standard could not be predicted with a
satisfactory level of confidence since the various techniques produced
different results. EPA acknowledges the fact that the various techniques
do produce different results since different assumptions and different
data bases are required for each specific model. Also, EPA agrees that
control strategies should be based on the most effective models. However,
effectiveness is in part determined by -he cost of gathering input data
and running a model. If simple models, such as rollback, indicate the
-------
need for extensive controls, EPA feels it may not be necessary to expend
additional time and resources to gather the information needed to run a
more sophisticated model which would reach the same general conclusion.
A sophisticated model, i.e., a photochemical dispersion model, would
appear to be most warranted in cases where there is some doubt whether
extensive controls are needed to attain the standard. EPA requires that
States attempting to demonstrate attainment and maintenance of the
t
revised ozone standard by 1982 without adopting reasonably available
control technology (RACT) regulations for large hydrocarbon sources must
employ photochemical dispersion modeling. The use of other less rigorous
analytical techniques are only acceptable in areas where RACT measures
are also scheduled for implementation. Where States are unable to
demonstrate attainment by 1982, EPA believes any of the models are
useful for indicating the magnitude of the ozone problem and for identi-
fying the need for major control programs to be implemented over the
next several years. As these control programs are implemented and the
State moves closer to attainment, it is likely that sufficient information
will be acquired to use dispersion models to adjust the control strategy.
Additionally, it should be noted that the city-specific version of EKMA
can account, to a limited extent, for temporal and spatial distribution
of sources.
Another commenter stated that the annual emission inventory may not
be readily adaptable to the models and to refine the inventory into
hourly segments may be very costly, time-consuming, and inaccurate. In
response, EPA points out that of the techniques specified, only photo-
chemical dispersion models require a detailed emission inventory to
-------
arrive at their predictions (with the exception of the more sophisticated
city-specific version of EKMA which can consider emission data). The
other techniques primarily utilize ambient air quality data. At the
same time, EPA recognizes the importance of an accurate emission inventory
in translating the requirements forecast by these simple models into
actual control programs. For example, suppose EKMA predicts that a 70
percent control requirement is needed to meet the standard. If the
emission inventory only includes 50 percent of the emissions, a 70
percent reduction in the inventory would only result in a 35 percent
reduction in actual emissions. Photochemical dispersion models, on the
other hand, do require explicit information concerning hourly emissions.
It would obviously be impractical to make hourly measurements for every
source. However, hourly rates can be estimated by superimposing observed
diurnal emission patterns on annual average emissions. Such patterns
have been observed in several cities so that it would be possible to
utilize annual emissions data.
Several persons commented that there is an inadequate understanding
of the relationship between hydrocarbons and ozone, and that controlling
hydrocarbon emissions may or may not be effective in reducing maximum
ozone concentrations. This particular issue was addressed in a recent
2
published report for the Manufacturing Chemists Association (MCA) which
noted a lack of any clear downward trend in Houston's ozone levels
despite control measures to reduce hydrocarbons. This report concluded
that existing ambient air quality data do not necessarily support the
hypothesis that reducing hydrocarbon emissions reduces ambient ozone
levels. At least two difficulties exist which prevent straightforward
-------
interpretation of the study's findings. First, the period of record was
relatively short (two to three years of data) and no attempt has been
made to normalize the trends for meteorological differences. It is
generally believed by EPA that at least a five year period of record may
be needed to discern a trend in air quality attributable to changes in
emissions. A recent review of ozone trend data conducted for EPA in
areas having long periods of records suggests that periods as long as
eight years may be required.3 Thus, while efforts are underway within
EPA to develop procedures for "normalizing" trends for differing meteorology
during short periods of record, at the present time trend analyses are
useful in only a limited number of areas. The second difficulty in
using the conclusions drawn from the study is that it appears as though
some of the controls may have been initiated prior to any substantial
air quality measurement programs.
EPA believes that convincing evidence exists to say that reducing
hydrocarbons will reduce ambient concentrations of ozone. This position
4-15
rests primarily upon experimental and theoretical studies which have
clearly established a physical cause-effect relationship between organic
pollutants and ozone in the presence of oxides of nitrogen. Smog chamber
studies have shown that maximum ozone concentrations are particularly
sensitive to hydrocarbon controls when the ratio of non-methane hydro-
carbons (NMHC) to nitrogen oxides (NO ) is lower than 15-20:1. In fact,
rt
the lower the ratio the more effective the hydrocarbon strategy is
likely to be. Examination of available NMHC and NO data suggests that
A
most U.S. cities experience ratios in the order of 6-12:1. Also, there
is a limited number of areas having ambient air quality data and emission
estimates over sufficiently long periods of record that tends to confirm
the theory of smog formation.
-------
Two commenters indicated that a consequence of relaxing the standard
could be the change of some urban areas from nonattainment to attainment
status, thus, permitting greater hydrocarbon emissions than allowed by
their former status. In one case the commenter argued that prior to
revising the standard EPA should ascertain that existing downwind viola-.
tions would not be further aggravated. The other commenter opposed the
revision because, when coupled with current EPA control strategy policy,
the burden of control would be shifted to the States where ozone is
measured and away from States where emissions originate. EPA does not
believe that consideration of such arguments is appropriate in setting
the national primary ambient air quality standard. The Clean Air Act
requires that primary standards be based solely upon effects on public
health. However, the consequences indicated by the commenters are valid
concerns in the formulation of policy and guidance to assist States in
developing a control strategy to meet the standards. EPA responds to
these comments by stating first, that few urban areas are expected to
change from nonattainment to attainment areas as a result of the revised
standard. EPA estimates that only five urban areas have the potential
for being redesignated as attainment areas. On this basis, it would be
difficult to anticipate widespread aggravation of air pollution in areas
downwind of an attainment area. Second, EPA does not consider the long
distance transport of precursors (e.g., hydrocarbons) to be as important
in the formation of ozone at downwind locations as the transport of
ozone itself. If the transported precursors are insufficient to violate
the ozone standard when they are at relatively high concentrations near
the source area, it is unlikely they will make significant contributions
-------
to observed violations in areas far downwind particularly in the presence
of freshly emitted precursors. The transport of increased amounts of
ozone itself, while more significant in contributing to downwind violations,
should generally be offset by the fact that the recorded violations
downwind will also be based on a higher standard.
EPA is concerned, however, that the transport of ozone itself may
be a problem when it originates in areas for which insufficient monitoring
data preclude classifying the area as either attainment or nonattainment.
EPA is now taking steps to identify areas which are currently unclassified
but which have a high potential for exceeding the national ozone standard.
Within such areas, States will be urged to require controls on existing
large stationary sources. If controls are not subsequently adopted, the
States will be required to monitor for ozone, whereupon, the area in
question will be classified nonattainment if violations are identified.
These areas would then be subject to the requirements to control hydro-
carbon emissions from existing stationary sources as in other nonattain-
ment areas. EPA believes that the present policy focuses the limited
resources of air pollution control agencies and industry on the areas
(i.e., nonattainment areas) where the controls will be most effective.
One commenter suggested that the chemical diethylhydroxylamine
(DEHA) be dispersed in the atmosphere to scavenge free radicals as an
effective means of controlling ambient concentrations of photochemical
oxidants. The use of various scavenger compounds has been suggested in
the past as a means of reducing pollutant concentrations. When considering
this type of approach, such concerns as how, when, and where to introduce
the chemicals to the ambient air constitute a problem whose solution is
8
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extremely difficult to resolve in practice. Furthermore, irradiation of
mixtures of NO , hydrocarbons, (HC), and DEHA was carried out in a
/\
large smog chamber at EPA's Research Triangle Park, North Carolina,
facility. The results indicate that after the DEHA is used up, smog
could sharply increase. Prolonged irradiation of DEHA resulted in
increased formation of ozone and ozone producing chemicals. Thus, EPA
does not consider DEHA to be a suitable additive to reduce ambient ozone
concentrations.
Several commenters claimed that the ozone problem is an urban
problem and EPA requirements for control strategies should concentrate
on the urban area while paying special attention to the present levels
of NOV and the NMHC/NO ratio. EPA agrees that the ozone attainment
X X
problem is primarily an urban problem. Consequently, the most stringent
requirements are imposed in urbanized areas with a population greater
than 200,000. Low NMHC/NO ratios primarily occur in such urbanized
/\
areas, thus the required controls would be effective in controlling
ozone levels. However, EPA does not feel it is appropriate to ignore
hydrocarbon emissions outside the urbanized areas because these emissions
may contribute to the overall ozone problem, particularly during adverse
meteorological conditions. EPA therefore believes it is justified in
requiring that large hydrocarbon sources (more than 100 ton/year potential
emissions) in rural nonattainment areas implement reasonably available
control techniques (RACT) to reduce their organic emissions.
One commenter claimed that EPA has failed to issue timely guidance
on control techniques as required by the Clean Air Act and as needed by
States in revising their implementation plans. The commenter's argument
-------
is based upon Section 108(b)(l) of the Clean Air Act which requires
control technique information to be issued simultaneously with the
issuance of health and welfare related air. quality criteria. EPA acknow-
ledges that no additional control technique information was issued
simultaneously with the recently revised health and welfare criteria.
This is because the original control technique information is not invali-
dated by revisions made to the air quality standard. Further, the Clean
Air Act does not require information on control techniques to be reissued
in the event that air quality criteria are revised, only that such
information from time to time be reviewed, modified, and reissued as
appropriate (Section 108(c).).
EPA has published a series of Control Technique Guidelines (CTGs)
which define reasonably available control technology (RACT) for stationary
sources of volatile organic compounds (hydrocarbons). This guidance is
designed to assist State and local jurisdictions in the development of
air pollution control regulations for hydrocarbons which contribute to
the formation of ozone. Although additional guidelines are planned for
future publication, the 1979 ozone plan submissions required of States
are to reflect the application of RACT to those stationary sources for
which EPA published CTGs by January, 1978. As additional CTGs are
published, States will be required to adopt and submit additional RACT
regulations on an annual basis beginning in January, 1980, for those
CTGs that have been published by January of the proceeding year.
One commenter inquired as to why the proposal did not retain the
original statement contained in Section 51.14(c)(4) which-allowed States
to assume that the hydrocarbon emission reductions necessary to attain
10
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the ozone standard would also be adequate to attain the national hydro-
carbon standard. EPA's response is that this statement was uninten-
tionally omitted from the June 22 proposal, and this omission is being
corrected in today's action. Previously, statements concerning the
attainment of the ozone standard and the hydrocarbon standard were both
contained in Section 51.14(c)(4). To take the actions described herein,
EPA is deleting (and reserving) paragraph (c)(4) of Section 51.14 and
establishing three new paragraphs (c)(7), (c)(8), and (c)(9). Paragraph
(c)(7) is to be used to set forth the four analytical techniques for
determining the amount of hydrocarbon reduction necessary to demonstrate
attainment of the ozone standard; paragraph (c)(8), describes specific
considerations to be made in developing the ozone control strategy; and
paragraph (c)(9) addresses attainment of the hydrocarbon standard.
2.2 SUBMITTAL OF SIP REVISIONS
Several industrial and governmental agency spokesmen expressed the
opinion that EPA should grant States extensions of up to nine months to
correct their SIPs to be consistent with the revision of the ozone
standard. EPA's response to this request is provided in detail in the
preamble to the revision of the ozone standard appearing elsewhere in
today's FEDERAL REGISTER. In summary, States are still expected to
submit their plan revisions to EPA on January 1, 1979, as required by
the Clean Air Act. These plans will most likely be based upon the old
standard of 0.08 p.p.m. However, once submitted, any State is free to
make the additional revisions necessary to account for the revised
standard, if they so desire. Thus, the time schedule for submitting the
latter revisions is to be determined by each State.
11
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3. OTHER CHANGES FROM PROPOSAL
In reviewing the June 22 proposed rule, EPA has determined that two
changes from the proposal are necessary even though no comments addressing
these particular matters were received. With regard to the first change,
EPA originally proposed to change the terms "photochemical oxidants" and
"oxidants" to "ozone" in 40 CFR Parts 51 and 52 to be consistent with
the proposed redesignation of the photochemical oxidant standard to an
ozone standard. EPA has decided not to proceed with the proposed nomen-
clature changes in Part 52 at this time. The reason for this decision
is that in numerous places throughout Part 52 the terms "photochemical
oxidants" and "oxidants" are used either as part of the title of a State
Implementation Plan or to denote use of the terms within the plan
itself. EPA therefore, feels that it would be proper to wait until
States made the appropriate nomenclature changes in their plans prior to
enacting any changes to Part 52.
The second change concerns EPA's proposal to allow States to use
photochemical grid models as one of four analytical techniques for
determining the needed hydrocarbon emission reductions. The intended
terminology for such models should have been photochemical dispersion
models. There are two major types of dispersion models - grid (or
Eulerian) and Lagrangian. EPA intends to allow either type model to be
used where appropriate. Thus, the more inclusive terminology (i.e.,
photochemical dispersion models) will appear in Section 51.14(c)(7)(i).
12
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4. REFERENCES
1. Uses, Limitations and Technical Basis of Procedures for
Quantifying Relationships Between Photochemical Oxidants and Precursors.
U.S. EPA, Research Triangle Park, N.C. 27711, EPA 450/2-77-021 a,
November, 1977, p. 31.
2. Examination of Ozone Levels and Hydrocarbon Emissions
Reduction. Final Report, DCN 77-100-151-04, Prepared by the Radian
Corporation, Austin, Texas, for the Manufacturing Chemists Association,
Washington, D.C., November, 1977.
3. Wayne, L., et al., Detection and Interpretation of Trends
in Oxidant Air Quality, Prepared for U.S. EPA by Pacific Environmental
Services, Santa Monica, Calif., EPA 450/3-76-034 (October, 1976).
4. U.S. Department of Health, Education and Welfare, Air
Quality Criteria for Photochemical Oxidants. AP-63, (March, 1970),
Ch. 2.
5. Altshuller, A.P., and J.J. Bufalini, "Photochemical Aspects
of Air Pollution: A Review," Environmental Science and Technology,
5_, 39 (January, 1971).
6. Dimitriades, B., Photochemical Oxidants in the Ambient
Air of the United States. U.S. EPA, Research Triangle Park, N.C. 27711,
EPA 600/3-76-017, (February, 1976), Ch. 3.
7. Air Quality Criteria for Ozone and Other Photochemical
Qxidants, Volume I. U.S. EPA, Washington, D.C., EPA 600/8-78-004,
(April, 1978),
Ch. 4.
8. Dimitriades, B., "Effects of Hydrocarbon and Nitrogen
Oxides in Photochemical Smog Formation," Environmental Sciences
and Technology. 6_, 253 (1972).
9. McCracken, M.C., et al., Development of an Air Pollution
Model for the San Francisco Bay Area. Volume I. NTIS No. UCRL-51920,
(October, 1975).
10. Dodge, M.C., Combined Use of Modeling Techniques and Smog
Chamber Data to Derive Ozone-Precursor Relationships. U.S. EPA,
Research Triangle Park, N.C. 27711, EPA 600/3-77-001b, p. 881,
(January, 1977).
13
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11. Dimitriades, B., "Oxidant Control Strategies, Part 1: An
Urban Oxidant Control Strategy Derived from Existing Smog Chamber
Data," Environmental Science and Technology. 1J_, p. 80 (1977).
12. Anderson, G.E., et al., Air Quality in the Denver Metro-
politan Region 1974-2000, Prepared for U.S. EPA by Systems Applica-
tions, Inc., San Rafael, Calif., EPA 908/1-77-002, (May, 1977),
Ch. 2.
13. Seinfeld, J.H., and K.R. Wilson, International Conference
on Oxidants, 1976 - Analysis of Evidence and Viewpoints. Part VI,
The Issue of Air Quality Simulation Model Utility, EPA 600/3-77-118,
(November 1977).
14. Air Quality Criteria for Ozone and Other Photochemical
Oxidants. Volume I. U.S. EPA, Washington, D.C., EPA 600/8-78-004,
(April 1978), Ch. 6.
15. Guideline for the Evaluation of Air Quality Trends,
Guideline Series OAQPS No. 1.2-014, U.S. EPA, Research Triangle
Park, N.C. 27711, (Feburary 1974).
16. Altshuller, A.P., "Evaluation of Oxidant Results at CAMP
Sites in the United States," Air Pollution Control Association J,
25., 19 (January 1975).
17. Trijoim's, J.C., et al., Emissions and Air Quality Trends
in the South Coast Air Basin. EQL Memo No. 16, Environmental Quality
Laboratory, California Institute of Technology, Pasadena, CA 91125.
18. Gise, J.P., Recent Ozone Trends in Texas, AICHE, 83rd
National Meeting, Houston, Texas, (March 1977).
19. Trijom's, J., et al.. Verification of the Isopleth Method
for Relating Photochemical Oxidant to Precursors, Prepared for U.S.
EPA by Technology Services Cooperation, Santa Monica, Calif., EPA
600/3-78-019, Ch. 2-3, (February 1978).
Date Administrator
14
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The Code of Federal Regulations, Title 40, Chapter I, Part 51, is
amended as follows:
1. Wherever the terms "photochemical oxidant(s)" or "oxidant(s)"
appear in Part 51, they are changed to read "ozone."
2. Appendix J is deleted and reserved.
3. Section 51.14(c) is amended by deleting and reserving paragraph (4)
and by adding new paragraphs (7) and (8) as follows:
§ 51.14 Control strategy: Carbon monoxide, hydrocarbons, ozone,
and nitrogen dioxide.
*****
(c) * * *
(4) [Reserved].
* * * * *
(7) In selecting an appropriate model to determine the amount of
hydrocarbon reductions necessary to demonstrate attainment of the ozone
standard, one of the following techniques must be applied:
(i) Photochemical dispersion models - These models are based on
the most accurate available physical and chemical principles underlying
the formation of ozone.
(ii) Empirical Kinetics Modeling Approach (EKMA) - This model
represents a compromise between rigorous treatment of chemical and
physical principles underlying ozone formation and dispersion and the
extensive data requirement that would be necessitated by such an approach,
(iii) Empirical and statistical models - These models reflect
observed relationships between ozone and other variables.
15
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(iv) Proportional rollback - This model assumes a linear relation-
ship between hydrocarbon emissions and ambient concentrations of ozone.
(8) In developing an ozone control strategy for a particular area,
background concentrations and ozone transported into an area must be
considered. States may assume that the ozone standard will be attained
in upwind areas.
(9) The degree of total hydrocarbon emission reduction necessary
for attainment of the national standard for ozone will also be adequate
for attainment of the national standard for hydrocarbons.
AUTHORITY: Sections 110 and 301(a), Clean Air Act, as amended (42
U.S.C. 7410, 7601).
16
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U21740
TAB 0
PART II
ENVIRONMENTAL
PROTECTION
AGENCY
PHOTOCHEMICAL
OXIDANTS;
MEASUREMENT OF
OZONE IN THE
ATMOSPHERE;
REQUIREMENTS FOR
PREPARATION,
ADOPTION, AND
SUBMITTAL OF
IMPLEMENTATION
Environmsntal PLANS
Protection Agency
RO^'TI o
DEC 20 1978
-------
26962
PROPOSED RULES
[6560-01]
ENVIRONMENTAL PROTECTION
AGENCY
[40 CFR Part SO]
CPRL 886-4 Docket Number OAQPS 78-81
PHOTOCHEMICAL OXIDANTS
Proposed Revisions la (he National Ambient
Air Quality Standard
AGENCY: Environmental Protection
Agency.
ACTION: Proposed rule.
SUMMARY: In accordance with the
provisions of Sections 108 and 109 of
the Clean Air Act as amended. EPA
has conducted a review of the criteria
upon which the existing primary and
secondary photochemical oxidant
standards are based. The revised crite-
ria are being published simultaneously
with the issuance of this proposed ru-
lemaking. The existing primary and
secondary standards for photochemi-
cal oxidants are currently set at 0.08
ppm, l-hour average not to be exceed-
ed more than once per year. As a
result of the review and revision of
health and welfare criteria, EPA pro-
poses to raise the primary standard
level to 0.10 ppm. 1-hour average. EPA
also proposes that the secondary wel-
fare-based standard remain at 0.08
ppm. 1-hour average. Other changes
proposed in this rulemaking include:
(1) changing the chemical designation
of the standard from photochemical
oxidants to ozone, and (2) changing to
a standard with a statistical rather
than deterministic form. i.e. allowable
exceedances will be stated as an ex-
pected value, not an explicit value.
During the period between this pro-
posal and final promulgation of the
standard. EPA will continue its exami-
nation of health and welfare criteria
and seek to further involve the public
and other affected parties In the final
decision on the air quality standard.
DATES: Comments must be received
by August 18, 1978. There will be a
public hearing at 9:00 aan. on July 18,
1978. This hearing may be extended
into the following day, July 19. as nec-
essary. The standard will be promul-
gated by the end of September. 1978.
ADDRESS: Send comments to Mr,
Joseph Padgett (MD-12V Director.
Strategies and Air Standards Division.
U.S. Environmental Protection
Agency. Research Triangle Park. NC
27711.
The public hearing will be held at:
Environmental Protection Agency, 401
M Street SW., Room 2117. Washing-
ton. DC 20460.
FOR PUHTUUK INFORMATION
CONTACT:
Mr. Joseph Padgett. Telephone: 919-
541-5204 (PTS 629-5204).
Availability of supporting informa-
tion: A docket (Number OAQPS 78-8)
containing information used by EPA
in development of the proposed stand-
ard is available for public inspection
between 8:00 ajn. and 4:30 p.m.
Monday through Friday, at EPA's
Public Information and Reference
Unit. Room 2922. Waterside Mall. 401
M Street SW., Washington. DC 20460.
These materials Include the "Air Qual-
ity Criteria'for Ozone and Other Pho-
tochemical Oxidants" and "Control
Techniques for Volatile Organic Emis-
sions from Stationary Sources", both
issued simultaneously with this pro-
posal. In addition, staff papers per-
taining to the form of the ozone stand-
ard, risk assessment method, second-
ary standard, and health panel assess-
ment are also available. These docu-
ments can be received upon request
from Mr. Joseph Padgett.
Revisions to 40 CFR Part 50. Appen-
.dix D, "Measurement Principle and
Calibration Procedure for the Mea-
-surement of Photochemical Oxidants
Corrected for Interferences Due to Ni-
trogen Oxides and Sulfur Dioxide"
and Appendix B. "Interpretation of
the National Ambient Air Quality
Standard for Ozone" are described
elsewhere in this preamble.
Revisions to 40 CFR Part 51 substi-
tuting the word "ozone" for "photo-
chemical oxidants" throughout that
part, and to Section 51.14 pertaining
to control strategies are being pro-
posed by EPA elsewhere in this issue
of the FEDERAL REGISTER.
Statements of the environmental.
, economic, and energy Impacts of im-
plementing this standard revision are
available upon "request from Mr.
Joseph Padgett, at the address shown
above.
SUPPLEMENTARY INFORMATION:
BACKGROUND •
On April 30.. 1971,- the Environmen-
tal Protection agency promulgated in
the FEDERAL REGISTER (36 FR 8186)
National Ambient Air Quality Stand-
ards for photochemical oxidants. The
scientific, technical, and medical basis
for these standards is contained In the/
air quality criteria document for pho'
tochemical oxidants published by the
U-S. Department of Health. Educa-
tion, and Welfare In March. 1970.
Both the primary and secondary
standards were set at a level of 0.08
ppm. hourly average not to be exceed-
ed more than once per year. The pre-
amble to the regulation stated:
"The revised national primary standard of
0.09 ppm Is based on evidence of increased
frequency of asthma attacks in some asth-
matic subjects on days when estimated
hourly average concentrations of photoche-
mical oxidant reached 0.10 ppm. A number
of comments raised serious questions about
the validity of data used to suggest Impair-.
ment of athletic peformance at lower oxi-
dant concentrations. The revised primary
standard Includes a margin of safety which
Is substantially below the most likely
threshold level suggested by this data. It Is
the Administrator's judgment that a prima-
ry standard of 0.08 ppm as a 1-hour average
will provide an adequate safety margin (or
protection of public health and will protect
against known and anticipated adverse ef-
fects on public welfare."
The asthma study cited above as evi-
dence for the original standard is
based on work by Schoettlin and
Landau. Effect level estimates from
this study have changed and are dis-
cussed elsewhere in this proposed reg-
ulation.
Oxidants are strongly oxidizing com-
pounds which are the primary con-
stituents of photochemical smog. The
oxidant found in largest amounts is
ozone (O>). a" very reactive form of
oxygen. Oxidants also include the
group of compounds referred to collec-
tively as peroxycylnitrates (PANs) and
other compounds all produced in
much smaller quantities than ozone.
Most of these materials are not emit-
ted directly Into the atmosphere but
result primarily from a senes of
chemical reactions between oxidant
precursors-(nitrogen oxides and organ-
ic compounds) in the presence of sun-
light. The principal sources of organic
compounds are the hydrocarbon emis-
sions from automobile .and truck ex-
hausts, gasoline vapors, paint solvent
evaporation, open burning, dry clean-
ing fluids, chemical plants and other
industrial operations. Nitrogen oxides
are emitted primarily from combus-
tion sources such as electric power
generation units, gas and oil-fired
space heaters, and automobile, diesel
and jet engines.
The reductions in emissions of rutro--
gen oxides and organic compounds are
achieved through ..Federal and State
programs which have been formalized
in regulations promulgated under the
Clean Air Act. The Federal programs
provide for the reduction in emissions
nationwide through the Federal Motor
Vehicle Control Program, the Federal
program for control of aircraft emis-
sions. National Emission Standards tor-
Hazardous Air Pollutants, and the de-
velopment of New Source Perform-
ance Standards. The State programs
provide for additional control meas-
ures through State Implementation
Plans in those areas of the country
where the Federal programs are not
sufficiently stringent to permit attain-
ment of air quality standards.
STATUTORY REQUIREMENTS AFFECTING
THIS PROPOSAL
Two sections of the Clean Air Act
govern the development of a National
Ambient Air Quality Standard. Sec-
tion 108. instructs EPA to document
the scientific basis for the standard.
and Section 109 provides guidance on
establishing standards and reviewing
criteria.
FEDERAL REGISTER, VOL 43, NO. 121—THURSDAY, JUNE 22, 1978
-------
PROPOSED RULES
26963
Air quality criteria are required by
section 108(a)(2) to accurately reflect
the latest scientific Information useful
in Indicating the kind and extent of all
identifiable effects on public health or
welfare which may be expected from
the presence of the pollutant in the
ambient air.
Simultaneously with the Issuance of
these criteria, the Administrator is re-
quired to propose primary and second-'
ary ambient air quality standards
based upon such criteria. The primary
standard is defined In section 109
as that ambient air quality standard
the attainment and maintenance of
which, based on such criteria and al-
lowing an adequate margin or safety,
is in the Administrator's judgment
requisite to protect the public health.
The secondary standard (section
109
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26964
PROPOSED RULES
effects such as biochemical changes.
morphological abnormalities, and ge-
netic changes have been shown in
some animal studies but the physio-
logical significance of-these effects re-
mains to be established.
5. There is a limited amount of data
that suggests that ozone may acceler-
ate the aging process in living organ-
Isms. Exposure of rabbits to unspeci-
fied concentrations of ozone for one
hour per week for a year has been re-
ported to induce premature aging
symptoms such as premature cartilage
calcification, severe depletion of body
fat. and general signs of senescence.
Inhalation of 0.20 to 0.25 ppm ozone
by animals and humans over 30 to 60
minute periods increased the rate of
sphering of red blood cells when their
blood samples were irradiated, sug-
gesting an acceleration In the aging of
the cells.
6. Acknowledgement of the fact that
ozone exposure is frequently accompa-
nied by exposure to other pollutants,
particularly sulfur dioxide (SO,), has
prompted several investigators to con-
duct laboratory evaluations of expo-
sure of humans to combinations of Ot
and SOi.
Exposures to 0.37 ppm Oi and 0.37
ppm SO* simultaneously have been re-
ported to produce enhanced decre-
ments in pulmonary function as com-
pared with either pollutant alone.
Other simultaneous exposure tests.
using d and nitrogen dioxide (NO,)
and Oj, NO, and carbon monoxide
(CO) produced few important physio-
logical changes and only mild symp-
toms. These findings suggest the need
for an adequate margin of safety as
well as the need-for more definitive
data.
• 7. There are no health studies that
link exposure to ozone or photochemi-
cal oxidants to an increase in human
mortality. A number of epidemiologic
studies have been designed and con-
ducted to demonstrate this effect, but
all have been negative or inconclusive.
8." Ozone accelerates the aging of
many materials resulting In rubber
cracking, dye fading and paint erosion.
These effects are related to- the total
dose of ozone and can occur at very
low levels, given long duration expo-
sures. Damage to vegetation occurs as
leaf Injury, decreased growth and
yield, and disruption or reproductive
functions.
9. All evidence presently available In-
dicates that around urban centers
with severe oxidant problems, the
majoc-concern Is the formation of pho-
tochemical oxidants from man-made
organic and nitrogen oxide emissions.
Control of these emissions will effect
significant reductions in ambient
ozone, peroxyacetylnitrate (PAN), al-
dehydes and photochemical aerosoL
GENERAL APPROACH TO SELECTING THE
LEVEL OF THE PRIMARY OZONE STAND-
ARD
'Revision of the National Ambient
Air Quality Standard for ozone re-
quires certain judgments b'y EPA
about the relationship between con-
centrations of ozone in the air and
possible adverse health effects experi-
enced by the public. This relationship
is greatly complicated by the fact that
there is variability of response among
individuals exposed to ozone, and that
there are numerous effects of ozone
on health occurring at different levels
of exposure. In selecting the proper
level for the revised standard. EPA
must make judgments relating to four
critical areas: - -
1. The range of demonstrated health 'ef-
fects.. "
2. The sensitive population.
• 3. The seriousness of the health effect and
the level at which the health effect has
been demonstrated to occur.
4. What constitutes an adequate margin of
safety to protect the public health.
DEMONSTRATE HUMAN HEALTH EFFECTS
AND EFFECTS OBSERVED IN ANIMAL
STUDIES
Tne purpose of this discussion Is to
describe the health effects attributed
to ozone that are of concern in setting
an ozone air quality standard. The dis-
cussion attempts to put these effects in
perspective, and where possible, relate
them to common personal experiences
of the average person.
Impaired Pulmonary Function and
Airway Resistance—Ozone Is a bron-
chiopulmonary Irritant which affects
the mucous lining, other lung tissue
and respiratory functions. Changes in
lung function appear as increased
airway resistance, reductions in vital
capacity, expiratory flow rates and dif-
fusion capacity. These effects - are
greater in exercising individuals and
individuals with hyper-reactive air-
ways (history of developing symptoms
during light activity in smog or history
of asthma). Changes In lung function
are accompanied by clinical symptonis
such as coughing, chest tightness, and
lower chest soreness. -
Because the human respiratory
system is endowed with a large capac-
ity, even airway resistance increases of
50 to 100 percent will not ordinarily be
perceived in normal Individuals. How-
ever, a portion of the population with
respiratory problems may be operating
at the limit of their lung capacity even
in normal activity states, and any In-
crease In air flow resistance will affect
their ability to perform or aggravate a
pre-existing pulmonary disease. For
healthy individuals engaged in strenu-
ous activity, a SO to 100 percent in-
crease In airway resistance might be
accompanied by shortness of breath
and fatigue. Since these sensations are
normally associated with strenuous ac-
tivity, it would be difficult to detect
the air pollution induced effect in
healthy persons. In a light activity
state, it is unlikely that any observable
effect could be noted from changes
even as high as 50 to 100 percent in-
crease in flow resistance.
Decreased Resistance to Infection—
This effect Is represented by an In-
creased rate of mortality In laboratory
animals subjected to both a bacterial
challenge and exposures to ozone. Ac-
cording to some studies, the effect
may be enhanced by the addition of
such stresses as heat, exercise, or the
addition of other pollutants in combi-
nation with the ozone dose. Despite
the lack of confirmatory studies in
man. and the uncertainties involved in
predicting human effects from animal
studies, most medical experts agree
that decreased resistance to Infection
most likely does occur in man and the
lack of such evidence is probably due
to the difficulty of detecting these re-
sponses in epidemiologic studies.
Aggravation of Chronic Respiratory
Disease—It is generally accepted by
the scientific community that there is
a link- between ambient oxidant levels
and aggravation of pulmonary disease.
This link was demonstrated by the
Schoettlin and Landau study which, re-
lated the frequency of asthma attacks
to measured ambient photochemical
oxidant concentrations. Several stud-
ies "have Investigated the aggravation
of emphysema and chronic bronchitis
without any. definitive links to photo-
chemcial oxidant concentrations.
Air pollution Is one of the many
stresses which can precipitate an
asthma attack or worsen the disease
state in persons with chronic cardio-
pulmonary disease. Other factors
which can act .like ozone in precipitat-
ing attacks include: respiratory infec-
tions, passage of cold fronts, seasonal
pollens, extreme heat or cold, and
even emotional disturbances.
" Eye Irritation—Eye irritation is asso-
ciated with selected chemical species
(such as PAN) in the photochemical
oxidant mix and other organic vapors.
There Is no evidence that eye Irrita-
tion Is associated with ozone. Since
EPA plans to redesignate the standard
from photochemical oxidants to ozone.
the eye irritation effect is not a criti-
cal one in establishing the standard
level.
Biochemical fleets—Experimental
exposures of human subjects to ozone
have produced changes in blood bio-
chemistry, such as increased fragility
of red blood cells and altered enzyme
activities in the serum. The signifi-
cance of these ozone-mediated changes
is not yet known, but changes of the
magnitude observed In experimental
exposures have not yet been linked to
any clinical diseases.
Carcinogenic, Mutagenic and Relat-
ed Effects—Studies have been conduct-
FEOERAL REGISTER, VOL 43, NO. 121—THURSDAY, JUNE 22, 1978
-------
PROPOSED RULES
26965
ed in an attempt to relate ozone to
carcinogenic, mutagenic, and related
effects. These studies are not deemed
to be important in setting ambient
ozone standards because of the failure
of researchers to replicate much of the
work and because of the questionable
significance to man of some effects ob-
served in lower life forms. The criteria
document states that the significance
of effects such as chromosomal aber-
rations has not been established.
EPA's Science Advisory Board has rec-
ommended not including some of the
studies in the criteria document lest
they receive unwarranted emphasis.
SENSITIVE POPULATION
Clinical and epidemiological studies
have shown that asthmatics and other
persons with reactive airways appear
most sensitive to changes in ozone con-
centrations and are thus judged to be
the principal sensitive group of con-
cern in setting the standard.- This is
because their airways are hyper-reac-
tive to irritants such as ozone.
Studies have also established that
exercise effectively increases the
ozone dose delivered to the target tis-
sues in the respiratory tract. Thus.
persons engaging in exercise are par-
ticularly vulnerable to the acutely irri-
tating effects of ozone. However, the
response of these groups to such
changes in concentrations has not
been systematically studied.
SELECTING THE LEVEL OF THE PRIMARY
STANDARD . .
The language of section 109(b)(l) re-~"
quires EPA to set a primary standard
that, based on the air quality criteria
and allowing an adequate margin of
safety, is requisite to protect the
public health.
Relevant to this charge, the Nation-
al Academy of Sciences reached the
following conclusion in 1974:
• • • in no case Is there evidence that the
threshold levels have clear physiological
meaning. In the sense that there are genu-
ine adverse health effects at the above some
level of pollution, but no effects-at all below
that level. On the contrary, evidence indi-
cates that the amount of health damage
vanes with the upward and downward vari-
ations m the concentration of the pollutant.
with no sharp lower limit.
The House of Representatives Com-
mittee on Interstate and Foreign Com-
merce has observed that the concepts
of threshold and adequate margin of
safety that underlie the language of
section 109(b)(l) of the Clean Air Act
are necessary simplifications to permit
the Administrator to set standards.
The criteria document confirms that
no clear threshold can be identified
for health effect due to ozone. Rather.
there is a continuum consisting of
ozone levels at which health effects
are certain, through levels at which
scientist can generally agree that
health effects have-been clearly dem-
onstrated, and down to levels at which
the indications of health effects are
less certain and harder to identify. Se-
lecting a standard from this contin-
uum is a judgment of prudent public
health practice, and does not imply
some discrete or fixed margin of safety
that is appended to a known "thresh-
old".
The uncertainties with which such a
judgment must deal are the result of
several factors. First, human suscepti-
bility to health effects vanes and we
cannot be certain that experimental
evidence has accounted for the full
range of susceptibility. Second, we
cannot be certain that all effects oc-
curring at low ozone levels have been
identified and demonstrated. Third,
variations in weatheacreate uncertain-
ty- as to the expected annual maxi-
mum ozone concentrations.
The decision is made more difficult
by the fact that the Clean Air Act. as
the Administrator interprets it, does
not permit him to take factors such as
cost or attainability into account in
setting the standard; it is to be a
standard which wfll adequately pro-
tect public health. The Administrator
recognizes, however, that controlling
ozone to very low levels is. a task that
will have»significant impact on eco-
nomic and social activity. It is thus im-
portant that the standard not be any
more stringent than protection of the
public health demands.
Human health effect levels cited in
the criteria document from published
studies vary from 0.15 to 0.30 ppm.
The studies documenting effect levels
are presented below:
DSMONSZE
i EFFECT LEVELS IB MAN
Aggravation of asthma
Redaction In pulmonary
function
Chest dtaconxfort and bntauoo
. of the respiratory tract
0 29 p/m—eplderaiotogie (aehoettlln and 0 19 p/m to 0 30 p/m elbilcal
Landau).
-------
26966
PROPOSED RULES
effect of reduced resistance to bacte-
rial infection in man., The criteria doc-
ument cites numerous epidemiologlcal
studies that fail to link increased mor-
tality or increased hospital admissions
with. ozone or oxidant exposures.
Those few studies which do suggest
such a link are described as Inconclu-
sive in the criteria document, and all
these studies are deemed to have seri-
ous limitations.
Based on the studies cited In 'this
section,. EPA concludes that the dem-
onstrated, human effects levels as cited
in the criteria document vary from
0.15 ppm to 0.30 ppm. Additional opin-
ions were sought from an advisory
panel of health experts (referred to
hereinafter as the health panel) and
other selected medical experts, who
were asked to assess the literature re-
ported in the.criteria document.
Estimates made by these experts are
based on their understanding and in-
terpretation of those health critieria.
A summary statement from the health
panel has been placed in 'the docket
and is available from EPA at the ad-
dress given earlier. As an added aid for
addressing' the uncertainties associat-
ed with setting an adequately protec-
tive standard, EPA has used an analyt-
ic technique of risk assessment.
Formal interviews of selected medical
experts were evaluated using a meth-
odology known as subjective probabil-
ity encoding. This analysis estimated
the probability of various health ef-
fects occurring in-sensitive persons at
alternative ozone levels. A report
which discusses the basis for and ap-
plication of the analytic method has
been placed in the docket and is avail-
able from EPA at the address given
earlier.
The most probable effect levels for
various health effects as estimated by-
the health panel and by the risk -as-
sessment procedure are shown below:
PROBABLE EFFECT LEVEL ESTIMATES— Estimates for sensitive population segments
[Parts per million]
Aggravation at asthma. Reduced resistance In bacteria
emphysema, and chronic Infection (animal studies)
bronchitis
Reduction In pulmonary
function
Chest discomfort and irritation
of the respiratory tract
Health panel judgment of effect level. -
Probable (median) effect level as estl- '
mated from interviews with health
experts—
0.15-0.29
0.1T
(0.14-0.25)
. 0.18
(0.01-0.38)
0.19-0.33
0.13
(007-018)
0.15-0.25
015
(0 11-0.18)
•Not available.
These estimates are based on the
most sensitive population-segments. In
the-case of the risk assessment inter-
views,-the experts were asked to focus
not only on the most sensitive popula-
tion group, but also on a very sensitive
portion of that group (specifically;
those persons who are more sensitive
than 99 percent of the sensitive group.
but less 'sensitive than 1 percent of
that group). However, these people
should not be considered as medically
. handlcaped as a result of their sensi-
tivity. Their outward appearance may
be perfectly normal-,-but when exposed -
they could have adverse reaction. The
lowest effect level estimate cited by
the health panel and those generated
through the expert- interview process
are reasonably consistent, ranging
from 0.15 to 0.18 ppm. Based on this
data and on the demonstrated effect
levels cited in the criteria document, it
can be concluded that health effects
have been demonstrated at ozone
levels of 0.15 ppm.
The criteria document contains sev-
eral indications of the uncertainties
discussed above that have/glven EPA
reason to believe that a standard of
0.15 ppm would not be adequately pror
tective. Of particular importance arer
(1) new and replicated animal studies
showing reduced resistance to infec-
tion at ozone levels of 0.10 ppm; (2)
Japanese epidemiologlcal studies re-
porting an increase In respiratory dis-
comfort and other symptoms in school
children at oxidant concentrations
below 0.15 ppm.
Evidence t>f reduced resistance to
bacterial infection has not reached the
point where It can be meaningfully
used- to extrapolate concentrations
that would similarly affect man. Most
experts agree, howeVer. that the effect
occurs in humans, and that it is only
the concentration at which r these ef-
fects occur that is uncertain. Further,
it is the kind of effect that is serious
enough in its implications to raise a
need for caution. Thus, there is a need
for setting a standard more.stringent
than the effect level which has been
demonstrated in human studies, in
order to account in some measure for
these unquantified but possibly seri-
ous effects. - -.
A similar caution is suggested by the
Japanese epidemiological studies. The
Science Advisory Board questioned the
merit of the studies because there
exists the possibility that some of the
symptoms observed1 may have been In-
duced 'by the subject's knowledge of
the prevailing levels. Nevertheless, it
would not be wise to totally disregard
the studies on the basis- of this possi-
bility.
An added uncertainty which must be
considered is the variation In air qual-
ity concentrations due to prevailing
meteorologic conditions. Since EPA's
proposed standard will be attained
when the expected number of hours
per calendar year with concentrations
above the standard level is equal to or
less than one, there is concern for the
magnitude of this one allowable excur-
sion. The probabilities for several al-
ternative standard levels that this ex-
cursion will exceed the demonstrated
effect level are shown below.
PROBABILITY THAT THE ALLOWABLE STANDARD
EXCEEDANCE WILL BE AS OR ABOVE THE
DEMONSTRATED EFFECT LEVEL OF 0.15 F/M
FOR ALTERNATIVE STANDARD LEVELS
Standard level (p/m>
Probability
0.08.
0.10.
0.12.
0.14.,
-------
PROPOSED RULES
26967
report has been submitted to the EPA
Science Advisory Board for review.
However, the review is not yet com-
plete nor has the report received ade-
quate review by others in the scientific'
community. Consequently, the prob-
ability estimates presented therein
and summarized below should be con-
sidered preliminary.
Probability that effect threshold wtB be exceeded S times or more in 5 years for alternate standard levels'
Hourly average standard . CD Aggravation of asthma, (2) Reduced resistance to (3) Reduction (4) Chest discomfort and Probability of exceeding 1 or
level (1 expected exceedance emphysema, and chronic bacterial Infection (animal In pulmonary Irritation of the respiratory more of the thresholds for
per year) • bronchitis studies) function tract the Individual categories
OOflppm .„ u,
0.08 ppm
0.10 ppm._._« ..
0.02
0.06
0.16
0.28-0 29
0.40
0.08 - ~ 0.11
0.1S 0.19-0.20
0.21 0.27
0 26 0.3S
&29 0.44
0.03
0.06
015
0.27
0.39
0.21
0.36
0.52
0.67
0.78-0.80
•Pmhnhllitv vnliin nnrmed an ranre to reflect runffff of anumDttom nmr^tne dtatrihutlim of pea* ozone vaitu*.
In the above table, the right-hand
column estimates the probability that
the threshold concentration for one or
more of the four health effect catego-
ries will be exceeded five or more
times in five years. The term "thresh-
old" as used in this context applies to
people in a narrowly defined range of
sensitivity, namely, persons more sen-
sitive than 99 percent of the sensitive
population but less sensitive than 1
percent of that group. For a standard
level of 0.10 ppm. the probability that
persons within this range of sensitivity
win experience an effect is about 0.5.
These figures illustrate several im-
portant points: (1) all alternative
standard levels reflect some risk. (2)
there is no sharp break in the prob-
ability estimates that would suggest
selecting one alternative standard
level over another, and (3) the choice
of a standard between zero and a level
at which health effects are virtually
certain (0.15 ppm) is necessarily sub-
jective.
The Administrator has thoroughly
considered the demonstrated effects
levels, our new understanding of the
study that served as the primary basis
for the 0.08 standard, and the uncer-
tainties introduced by the various
studies discussed in the criteria docu-
ment. Based upon an these data, it has-
been determined that a standard of
0.08 ppm does not appear necessary to
protect the public health. However, at
this time it appears that a standard
above 0.10 ppm would- not adequately
protect public health. It is therefore-
proposed that the primary standard1
for ozone be revised1 to- ft 10 ppm. Com-
ments are solicited on whether a less
stringent standard could adequately
protect public health.
OTHER ASPECTS OPTHK STANDARD
Chemical Species of the Standard—
EPA is proposing to redesfgnate the
photochemical oxidant standard* as an
ozone standard. Evidence in the re-
vised criteria document indicates that:
1. The majority of data, presented in the
revised criteria doaimmit Is based on ozone
exposure. Nearly an of the clinical and toxl-
cological studies are based on effects of
3. Some more recent epldemiological stud-
ies associate advene effects- more closely
with ozone than with total oxidants.
3. Effects observed in clinical studies with
ozone alone are similar to those effects ob-
served In epidemiologial studies where
ozone occurs, along the complex mix of
urban pollutants. These findings from the
health data further suggest that health ef-
fects- observed during periods of elevated
photochemical oxidants concentrations are
reasonably attributable primarily to ozone
In the ambient air.
The-existing standard for photoche-
mical oxidant ostensibly was estab-
lished for the entire class of this com-
plex' mix of compounds. Unfortunate-
ly, there are no satifactory methods
for accurately and reliably measuring
this collective class of pollutants. The
reference method used to estimate am-
bient oxidant levels and to determine
compliance with trig standard has
always measured only a single compo-
nent of the oxidant mix—ozone. Thus.
the chemical designation of the stand-
ard and the chemical composition of
the pollutant measured to determine
compliance have not been stated con-
sistently. Ambient ozone concentra-
tions can range from approximately 65
percent to nearly 100 percent of the
total photochemical oxidant concen-
tration; consequently, ozone can be a
poor indicator of the quantity and
composition of the non-ozone oxidant
In the ambient air. Also of concern is
the fact that aside from PAN. which is
an important constituent of the photo-
chemical oxidant mix. the non-ozone
oxidants remain essentially unidenti-
fied, cannot be measured, and have
not been uniquely associated with ad-
verse effects,
The inconsistencies cited' above
argue for ch»»>g<"g the designation
from a total photochemical oxidant
standard' to, an ozone standard.
Promulgation of a Primary Stand-
ard for PAS—EPA does not propose to
establish a separate standard for PAN
at this time. Although PAN is ah eye.
irritant, the health data upon which
to base a separate PAN standard are
inadequate and routine PAN measure-
ment methods are not available. Most
of the studies which have documented
the effects of PAN have used ozone or
total oxidants as a surrogate for the
material causing the adverse effect.
Ozone is not a reliable indicator of
PAN. Recorded data shows ozone/
PAN ratios ranging from 3:1 to 150:1.
This variation in the ratio of ozone to
PAN makes it extremely difficult to-
correlate the eye irritation effects of
PAN with specific ozone values. How-
ever, it has been shown that at ozone
levels of about 0.1 ppm. PAN concen-
trations win be at a level below those
associated with perceptible eye irrita-
tion effects. This is true even for low
ozone/PAN ratios.
Despite the lack of a separate PAN
standard, those measures taken to
reduce oxidant/ozone precursor emis-
sions will also reduce PAN levels. In
fact, smog chamber studies indicate
that, control of oxidant precursor emis-
sions have a greater impact-on PAN
levels than on ozone/oxidant levels.
Farm of the Standard—The current
standard specifies that the hourly
average ozone concentration must not
exceed 160 /ig/m* (approximately 0.08
ppm) more than once per year. As dis-
cussed in a report placed in the docket
and available from EPA at the address'
given earlier, this deterministic (once-
per-year) approach has several limita-
tions, one of which is the fact that it
does not adequately take into account
the random nature of meteorological
variations. The original purpose of
permitting a single exceedance was to
. allow, for unique meteorological condi-
tions that were unrepresentative of air
quality problems in a given area. Un-
fortunately, the current standard does
not achieve this objective because it
specifies In effect that there be zero
probability that the second-highest
concentration measured in a year
FEDERAL REGISTER; VOL 43, NO. 121—THURSDAY. JUNE 22, 1978
-------
26968
PROPOSED RULES
exceed the standard level. However,
when'a single exceedance of the stand-
ard is permitted, there is a definite
possibility that a second or third ex-
ceedance will also occur. If this prob-
ability is to be zero, there cannot be
even a single exceedance of the stand-
ard. This limitation means that com-
pliance with the standard, and conse-
quently pollutant emission control re-
quirements, would be determined qn
the basis of exceedingly rare adverse
weather conditions.
Another fundamental problem wijh
the current standard is that it focuses
on a single measured value, the
second-highest observation. This value
is subject to instrument error, is not a
stable statistic, and also will vary in
any given area over a period of time.
For a given year, the true second-high-
est value in an area may not be. ob-
served because of gaps in the monitor-
ing record. Use of such a random sta-
tistic to- determine compliance and
levels of control can lead to values
that are unrepresentative of the true
air quality problems in an area.
Because of these and other limita-
tions in the current form of the stand-
ard, EPA proposes that the ozone air
quality standard be stated in a statisti-
cal' form. This would mean that the al-
lowable number of exceedances of the
standard would be expressed as an
average or expected number per year.
The standard would be attained when
the expected number of hour per cal-
endar year with concentrations above
0.10 ppm is less than or equal to one.
The average or expected value would
be calculated from data obtained over
several years, as .explained below.
Definition of When the Standard is
Attained—EPA proposes to add Ap-
pendix H to 40 CFR Part 50 to explain
how to determine when the standard
is or is not being attained. The proce-
dure proposed in Appendix H requires
that States compute a three-year
moving average of -the number of
hours above the standard and adjust
that average for missing* data. This
would, mean that the allowable
number of exceedances of the stand-
ard, i.e.. the times when the standard
level is allowed to be exceeded, would
be expressed as an expected number of
hours, during the three-year period.
' The central feature of this approach is
a description of how missing hourly
values are handled. The calculations
required would add the number of ex-
ceedances of the standard expected to
be present in the hourly values miss-
ing during any calendar year to the
actual number of exceedances meas-
ured during that year. The three-year
average of the expected number of ex-
ceedances so computed would have to
be equal to or less than one in order to
attain the ozone air quality standard.
There is strong similarity between
determining attainment of the present
oxidant standard and determining at-
tainment of the proposed ozone stand-
ard. In both cases, the number of ex-
ceedances of the level of the standard
is used. The current approach requires
that the level of the standard never be
exceeded more than once in any year
while the proposed form of the stand-
ard would permit two or more excee-
dances in any year provided that the
average number of exceedances during
the most recent three-year period does
not exceed I. For example, if three
successive years of ozone monitoring
data showed annual exceedances of 2,
1, and 0, the current standard would
not be attained since the first year re-
corded more than one exceedance.
Under the proposed approach, the
same exceedance pattern would lead
to a decision of attainment since the
average number of- exceedances for
the three years was not above one. De-
tails of the calculations discussed
above are given in Appendix H.
A period of three successive years
was chosen as the basis for determin-
ing attainment for two reasons. First.
increasing tha number of years in-
creases the stability, of the resulting
average number of exceedances.
Stated differently, as more years are.
used, the greater the chance of mini-
mizing the effects of. an extreme year
caused by unusual weather conditions.
The second factor is that extending
the number of successive years too far
Increases the risk of averaging data
during a period in which a real shift in
emissions and air quality has occurred.
•This would penalize areas showing
recent improvement and similarly
reward areas which are experiencing
" deteriorating ozone air quality. Three
years is thought by EPA to represent
a proper balance between these two
considerations.
Another modification that was con-
sidered during 'this review was to
change the form of the standard to
permit one calendar day in which the
hourly standard could be exceeded.
This form of the standard has several
advantages, including: (1) the require-
ments for less manipulation and inter-
pretation of data in calculating attain-
ment or non-attainment. (2) reduced
time and resources on the part of state
and local agencies to validate low con-
centration values occurring in the
evening and morning hours, and (3)
greater stability in design statistics
needed for control strategy develop-
ment'. However, based on potential
conflicts with other air quality man-
agement programs such as prevention
of significant deterioration, EPA does
not propose to make such a change in
the form of the ozone standard at this
time.
EPA believes the statistical form of
the standard coupled with the proce-
dures explained in Appendix H will
ameliorate the problems experienced
with the present form of the standard.
Comments are invited on the form of-
the standard and the method in*-Ap-
pendix H for determining when the
standard is or is not being attained.
Averaging Time of the Standard—
EPA does not propose a change in the
current one-hour averaging time of
the standard. Most clinical studies
clearly show impairment of lung func-
tion in moderately exercising healthy
subjects exposed to ozone for two
hours. Since the impact of ozone is re-
lated to the total dose delivered to the
respiratory tract and since more in-
tense exercise would shorten the time
required to deliver an equivalent dose,
exposure durations of less than two
hours are of concern for protection of
individuals engaged in intense exer-
cise. A recent clinical study published
last year by DeLucia and Adams con-
firms this thesis at its shows lung
function changes in exercising sub-
jects after a one-hour exposure to rela-
tively low ozone levels.
WELFARE EFFECTS AND THE SECONDARY
STANDARD
The Clean Air Act mandates the set-
ting of a national secondary ambient
air quality standard to protect the
public welfare from any known or an-
ticipated adverse effects associated
with the presence of an air pollutant
in the ambient air. Ozone and other
photochemical oxidants constitute a
form of air pollution that affects vege-
tation and materials. The resultant
economic loss has been estimated to be
in the range of several hundred mil-
lion dollars per year nationwide. Non-
quantifiable losses to the natural envi-
ronment occur as welL A report dis-
cussing these issues has been placed in
the docket and is available from EPA
at the address given earlier. The fol-
lowing material summarizes that
report. Exposure of vegetation to
harmful levels of ozone may result in
leaf injury, decreased growth and
yield, or reproductive effects. Visible
leaf injury is the most readily detect-
able symptom- of ozone exposure and
for this reason has commonly been
used in attempts to quantify damage
to economic crops. Decreases in
growth and yield can occur without
such visible symptoms; however, since
leaf injury is the most readily detect-
able and frequently reported symptom
of ozone damage, this effect provides
the best available data base for evalu-
ating alternative standard levels.
While it is not currently possible to
make definite correlations of foliar
Injury with reductions in yield, several
investigators have suggested that
foliar injury rates in^the range of 5 to
10 percent could produce detectable
reductions in growth or yield, depend-
ing on the timing .of the injury and
other environmental factors. Ozone
exposures which may be reasonably
FEDERAL REGISTER, VOL 43, NO. Ill—THURSDAY, JUNE 22. 1978
-------
PROPOSED RULES
26969
expected to produce injury ratings
within this range in commercially im-
portant crops or indigenous flora are
undesirable; therefore, the basis of the
secondary National Ambient Air Qual-
ity Standard for ozone will be to pro-
tect against such exposures.
The .effects of ozone~ on vegetation
are not linearly dependent on the dose
(product of concentration and expo-
sure duration) sustained by the plant.
A given dose applied over a short
penod of time is more damaging than
if it were applied over a longer period.
A mathematical model has been used
to summarize for several crops the ex-
perimental results which depict the
variation in foliar response with short-
term (0.5-hour to 8-hour) ozone expo-
sures. Based on these results, no com-
mercially important crop is predicted
to receive more than 3 percent leaf
injury as a result of short-term peak
ozone exposures at sites where an
hourly average concentration above
0.08 ppm is expected t« occur only'
once per year. Such a level of air qual-
ity should thus protect agricultural
crops from detectable effects on
growth and yield due to short-term
peak ozone exposures, even after al-
lowing for possible interaction be-
tween ozone and other air pollutants.
In addition, studies which have exam-
ined the effects of long-term, intermit- •
tent ozone exposures on growth and
yield of vegetation indicate that no de-
tectable effects are predicted to occur
as a result of the long-term pattern of
ozone exposures anticipated when an
hourly average concentration of 0.08
ppm is expected to be exceeded only
once per year.
It should be noted that the above
predictions were based on air quality
relationships (e.g.. the ratio of the 1-
hour-average peak concentration to
the corresponding 8-hour-average
value) which were judged to be repre-
sentative for urbanized areas where an
hourly average concentration above
0.08 ppm is expected to occur only
once per year. Equivalent relation-
ships for rural areas have not been
quantified, yet there is reason to be-
lieve that higher 8-hour-average con-
centrations may occur at a rural site
than at an urban site when both are
attaining the same hourly average
standard. EPA has attempted to factor
this uncertainty into its analysis of al-
ternative hourly average standard
levels, but is soliciting comments as to
whether the standard should be set
for an averaging time of 8 hours
rather than 1 hour in order to insure
the protection of vegetation in rural."
areas.
Material damage due to ozone can be
described as an acceleration of aging
processes,' e.g.. rubber cracking, dye
fading, and paint weathering. In con-
trast to the effects of ozone on vegeta-
tion, these effects appear to be gov-
erned by the ozone dose sustained by
the material. As a result, the annual
average concentration will determine
the rate at which material damage
occurs, and any nonzero ozone concen-
tration (including natural background
levels) will contribute to the deteriora-
tion of sensitive materials if the expo-
sure is sustained long enough. In
remote areas selected to be as free
from man-made influences as possible,
annual average ozone concentrations
are comparable with those seen in
urgan areas, due to strong nighttime
scavenging of ozone in urban areas by
man-made pollutants. For the above
reasons, no effect-based rationale can
be offered to decide the level of the
secondary standard needed to protect
materials. As a result, EPA proposes to
evaluate the level of the secondary
standard principally on the basis of
the air quality required to protect
vegetation from growth and yield ef-
fects, since- there is no level at which
some material'damage will not occur
given sufficient times-
Based on the preceding consider-
ations, EPA proposes to set the sec-
ondary ozone air quality standard
level at an hourly average, concentra-
tion of 0.08 ppm expected to be ex-
ceeded only once per year.
ECONOMIC, ENERGY, AND
ENVIRONMENTAL IMPACTS •
As has been noted previously, the
Clean Air Act specifically requires
that National Ambient Air Quality
Standards be' based on scientific crite-
ria relating to the level that should be
attained to adequately protect public
health and welfare. EPA interprets
the Act as excluding any consideration
of the cost of achieving such a stand-
ard in determining the level of the
standard. However. In compliance with
the requirements of Executive Orders
11821 and 11949 and OMB Circular A-
107 and with the provisions of the re-
cently issued Executive Order 12044
for rulemaklng proceedings which are
currently pending, EPA has prepared
an analysis of economic impacts asso-
ciated with efforts to attam this pro-
posed standard.
Ozone air pollution is a pervasive
problem throughout the country.
Most urban and many rural areas
exceed the existing standard. Even if a
less stringent standard (as proposed) is
promulgated, most of the major urban
areas are not expected to attain the
standard in the near-term. Control of
the organic precursor materials which
generate photochemical oxidants is a
major effort in" this country and a
multi-billion dollar program. The ex-
isting control program includes meas-
ures to reduce organic emissions from:
automobile and truck exhausts, pro-
duction of chemical and petroleum
products, the dry-cleaning industry*
most painting operations including the
automotive industry, and other indus-
trial operations.
Because the attainment problem in
most urban areas is so severe, the pro-
posed relaxation of the standard is not
expected to change the level of control
requirements in the near-term. How-
ever, the move to a 0.10 ppm standard
would eliminate the need for major
control programs in many rural and
wilderness areas which currently
exceed the standard.
With the proposed relaxation of the
standard, the longer-range outlook
does indicate that many urban areas
will achieve the standard by 1987.
However, even with aggressive control
programs, it will be very difficult for
some urban areas to achieve the pro-
posed standard within the next 10
years.
In addition, a document has been
prepared assessing the impacts that
efforts to attain the proposed stand-
ard may have on the nation's energy
requirements. Control of oxidant pre-
cursors will often be accomplished by
recovery of organic materials that
would otherwise be emitted" to the at-
mosphere, or by more efficient com-
bustion. Because of such energy sav-
ings, this document concludes that ox-
idant precursor control measures may
well lessen the nation's energy re-
quirements.
Furthermore, environmental im-
pacts associated with control of oxi-
dant precursors have been examined
in a document available in docket
number OAQPS 78-8. This study indi-
cates that modifying the current
standard as proposed should have
minimal environmental impacts.
Copies of the above-mentioned anal-
yses of the economic, energy, and envi-
ronmental impacts involved in the pro-
posed ~ ozone standard are available
from EPA at the address given earlier.
REVISIONS TO PART 50 REGULATIONS '
In addition to the revised standard.
this action necessitates two other revi-
sions to Pan 50 as follows:
1. In Appendix D. as well as in the Cable of
sections for Part 50. the title is revised to
read as follows Appendix D—Measurement
Principle and Calibration Procedure for the
Measurement of Ozone in the Atmosphere.
The substitution of "ozone" for "photoche-
mical oxidants- corrected for Interferences
due to nitrogen oxides and sulfur dioxide" is
a result of the proposed change in the
chemical designation of the standard.
2. Appendix H. "Interpretation of the Na-
tional Ambient Air Quality. Standard for
Ozone". is added because additional guid-
ance is necessary to understand the statisti-
cal nature of the revised standard.
REVISIONS TO PART 51 REGULATIONS
Elsewhere in this issue of the FEDER-
AL REGISTER three revisions to Part 51
are proposed concurrently with the re-
vision to the photochemical oxidant
standard. They are as follows:
FEDERAL REGISTER, VOL 43, NO. 121—THURSDAY, JUNE 27, 1978'
-------
26970
PROPOSED RULES
1. The term "photochemical oxidants"
will be changed to "ozone" throughout Part
51
2. Section 51.14. "Control strategy: Carbon
monoxide, hydrocarbons, photochemical ox-
idants. and nitrogen dioxide". Is being re-
vised to allow the states to use any of four
analytical techniques in the place of Appen-
dix J to calculate the percent hydrocarbon
reduction needed to attain the ozone stand-
ard.
3. Appendix J Is being deleted from Part
51.
With regard to SIP development under
Part 51. the proposed ozone standard should
have little impact on the attainment status
designation of most areas. However, where -
sufficient data is available to support a
change in designation, either the State or
EPA may Initiate such a change under the
terms of section 107 of the Clean Air Act
after the standard is promulgated. The pro-
posed standard may Impact" the control
strategies needed in some areas. These Im-
pacts will need to be analyzed on a case-by-
case basis and EPA will provide guidance on
this matter when the standard is promulgat-
ed. The standard will not substantially
affect New Source Review requirements.
FEDERAL REFERENCE METHOD •
The measurement principle and cali-
bration procedure applicable to refer-
ence methods for measuring ambient
ozone concentrations to determine
compliance with the standard are not
affected by the proposed amendments.
Elsewhere in this issue of the FEDERAL
REGISTER, however, EPA is proposing
to replace (supersede) the current cali-
bration procedure with a new. superior
calibration procedure based on ultra-
violet photometry. The measurement
principle and the current calibration
procedure are set forth in Appendix D
of 40. CFR Part 50 (as amended in the
February 18. 1975 issue of the FEDERAL
REGISTER. 40 FR 7042). Reference
methods—as well as equivalent meth-
ods—for monitoring, ozone are desig-
nated in accordance with 40 CFR Part
53 (40 FR 7044). A list of all methods
designated by EPA as reference or
equivalent methods for measuring
ozone is available from any EPA re-
gional office, or from EPA. Depart-
ment E (MD-76). Research Triangle
Park, NC 27711.
PUBLIC PARTICIPATION
EPA has solicited public comment
and critique, on draft revisions to the
criteria document as well as comments
on several staff position papers de-
scribing possible modifications to the
standard. Comments on the two draft
revisions of the criteria document
have been considered in the final doc-
ument published simultaneously with
the issuance of this proposal. An ex-
planation of how EPA addressed each
of these comments will be provided as
a part of the docket number OAQPS
78-8 prior to promulgation of this
standard. On December 30. 1977. EPA
announced in the FEDERAL REGISTER
(42 FR 65264) a public meeting to dis-
cuss issues related to possible revisions
of the national ambient air quality
standard for photochemical oxidants.
In that notice, EPA announced the
availability of staff papers describing
preliminary recommendations: (1) re-
designating the standard from oxidant
to ozone; (2) proposing not to set a
separate standard at this time for per-
oxyacetylnitrate (PAN); (3) redefining
the standard in a statistical, rather
than deterministic, form; (4) retaining
the one-hour averaging time for the
standard; and (5) establishing the
standard level somewhere in the range
between 0.08 ppm and 0.15 ppm. The
public meeting was held'January 30.
1978; a transcript of the meeting is
available through- docket ' number
OAQPS 78-8. During the meeting and
afterwards, comments were received
which addressed the aforementioned
issues as well as other topics related to
the standard or to control measures
required to attain the standard. The
greatest area of controversy was with
the interpretation of health data. In-
dustrial groups criticized much of the
available data as incomplete, unreli-
able, or not applicable to the determi-
nation of health effects threshold.
Most of these groups maintained that
there exists little evidence for health
effects below 0.25 ppm. As discussed
elsewhere in this proposed regulation,
EPA does not agree with this judg-
ment of a demonstrated effect level.
Comments from other groups such as
the American Lung Association argued
that hyperreactive asthmatics may
suffer health effects below 0.15 ppm
and suggested that there may not be a
no-effect threshold for ozone.
The use of the "risk" analysis ap-
proach to aid in selecting a standard
was generally supported. However,
there were several criticisms jot the
specific methodology selected by EPA.
The American Petroleum Institute
(API) doubted that the population
considered at risk could be adequately
characterized. The health department
of the city of Houston. Texas did not
feel the probability encoding tech-
nique was valid for extending the
range of knowledge beyond experi-
mental data. The API also called on
EPA to seek peer review of the entire
risk assessment methodology. We have
accepted the API's suggestion for fur-
ther review of the methodology, as
mentioned earlier, and have submitted
the material to the EPA Science Advi-
sory Board for review. We have also
been cooperating with the API by pro-
viding them with information on all
aspects of the development of the risk
assessment methodology. We do not
agree with the city of Houston on the
lack of the utility of the probability
encoding technique. The approach is
probably the best technique for quan-
tifying an expert's knowledge of un-
certainty. Some measure of this uncer-
tainty is extremely useful as input for
establishing an adequately protective
standard.
Changes in the form of the standard
and the chemical designation of the
standard received little criticism as a
result of the public review process.
The recommendation not to promul-
gate a PAN standard at the present
time was not challenged.
A number of comments were re-
ceived regarding implementation of
the air quality standard. Representa-
tives of industry and areas with high
ozone concentrations felt that the cur-
rent air quality standard could not be
attained. The principal reasons cited
were high 'natural background levels
of ozone and transport of ozone from
other locations. In addition, comments
were made that the hydrocarbon
abatement strategies required for im-
plementing a stringent standard were
unproven. ineffective, and excessively
destructive of social and economic ac-
tivity. Since these factors are not re-
lated to health and welfare criteria,
they are not germane to the establish-
ment of the standard, but are impor-
tant considerations in developing state
implementation plans. EPA will assure
that these comments are given proper
attention.
Dated: June 9.1978.
DOUGLAS M. COSTLE,
Administrator.
EPA proposes to amend Part 50 of
Chapter I. Title 40, of the Code of Fed-
eral Regulations as follows:
1. Section 50.9 is revised as follows:
§50.9 National primary and secondary
ambient air quality standards for
ozone.
(a) The level, of the national primary
ambient air quality standard for ozone
measured by a reference method based
on Appendix D to this part and desig-
nated in accordance with Part 53 of
this chapter, or by an equivalent
method designated in accordance with
Part 53 of this chapter, is 0.10 part per
million (196 jig/m3). The standard is
attained when the expected number of
hours per calendar year with concen-
trations above 0.10 part per million
(196 pg/m3) is equal to or less than
one, as determined by Apperfdix H.
(b) The level of the national second-
ary ambient air quality standard for
ozone, measured as in § 50.9(a) is: 0.08
part per million (157 jig/m3). The
standard is attained when the expect-
ed number of hours per calendar year
with concentrations above 0.08. part
per million (157 pg/m3) is equal to or
less than one. as determined by Ap-
pendix H.
2. In Appendix D, as well as in the
table of sections for Part 50, the title
is revised to read as follows' Appendix
D—Measurement Principle and Cali-
bration Procedure for the Measure-
ment of Ozone in the Atmosphere.
FEDERAL REGISTER, VOL 43, NO. 121—THURSDAY, JUNE 22. 1978
-------
PROPOSED RULES
26971.
3. Appendix H is added as follows:
APPENDIX H—INTERPRETATION OF THE
NATIONAL AMBIENT AIR QUALITY STANDARD
FOR OZONE
1. General—This Appendix explains how
to determine when the expected number of
hours per calendar year with concentrations
above 0.10 part per million (196 pg/m*) is
equal to or less than one. An expanded dis-
cussion of these procedures and associated
examples are contained in the "Guideline
for Interpretation of the Ozone Air Quality
Standard." For purposes of clanty in the
following discussion, it Is convenient to use
the term "exceedance" to describe an
hourly ozone measurement that is-greater
than the level of the standard. Therefore.
the phrase "expected number of hourly
values with concentrations above the level
of the standard" may be simply stated as
the "expected number of exceedances."
The basic principle in making the above
determination is. relatively straight-forward.
Most of the complications that arise in de-
termining the expected number of annual
exceedances are consequences of accounting
for incomplete sampling. In general, the
average number of exceedances per calendar
year must be less than or equal to 1. In its
simplest form, the number of exceedances
at a monitoring site would be recorded for
each calendar year and then averaged over
the past three calendar years to > determine
if this average is less than or equal to L
2. Interpretation of expected number of ex-
ceedances.—The ozone standard states that
the expected number of exceedances per
year must be less than or equal to 1. The
statistical term, "expected number" is basi-
cally an arithmetic average. The following
example explains what it would mean for an
area to be in compliance with this type of
standard. Suppose a monitoring station rec-
ords an ozone value for every hour of the
year during the past 3 years. At the end of
each year, the number of hours with con-
centrations above 0.10 part per million is de-
termined and this is averaged with the re-
sults of previous years. As long as this arith-
metic average remains "less than or equal to
1" the area is in compliance. -
3. Estimating the number of exceedances
for a year.—ID general, a value is not availa-
ble for each hour of the year and it will be
necessary to account for these missing
values when estimating the number of ex-
ceedances for a- particular calendar year. It
should be noted that the purpose of these
computations is to' determine if the expect-
ed number of exceedances per year Is less
than or equal to 1. Thus, if a site has two or
more observed exceedances each year,-1he-
standard is not attained- and it is not neces-
sary to use the procedures of this section to
account for incomplete sampling.
The-term "missing value" is used here in
the general sense to describe all hours that
do-not have an associated ozone measure-
ment. In some cases, a measurement might
actually have been missed but in other cases
no measurement may have been scheduled
for that hour.
Many State and local air pollution-control
agencies deliberately design their schedules
so that missing data associated with instru-
ment maintenance occur at times when
there is virtually no- chance of violating the
standard. Also, in some areas the seasonal
pattern of the pollutant is so pronounced
that entire months may be omitted because
it is extremely unlikely that the standard
would be exceeded. To avoid unfairly penal-
izing such areas, some allowance must be
made to allow for hours that were not actu-
ally measured but would certainly have
been below the standard. This introduces a
complication in that it becomes necessary to
define under what conditions a missing
hourly value may be assumed to have been
'less than the level of the standard. The fol-
lowing criteria shall be used for ozone.
A missing hour of ozone data shall be as-
sumed to be less than the level of the stand-
ard If either of the following conditions is
met:
(a) An individual missing hourly value
shall be assumed to be less than the level of
the standard if both the hour preceding and
the hour following this missing value have
values that do not exceed 79% of the level
of the standard^
(b) In cases where consecutive mining
hours occur, a missing hour shall be as-
sumed to be less than the level of the stand-
ard If no hourly value for that same hour of
any day In the particular month in question
has exceeded 75% of the standard level
based upon the most recent, three calendar
years of available monitoring data.
Let z denote the number of missing values
that is assumed to be less than the stand-
ard. Then to establish that the ozone stand-
ard has been met. the following formula
shall be used to estimate the number of ex-
ceedances for the yean
(Hl-l)
(1)
Where:
N=the number of hours in the year.
n=the number of hourly ozone measure-
ments.
v=the number of hourly values a'Bove the
level of the standard,
z=the number of hours assumed to be less
than the standard level, and
e=the estimated number of'exceedances
for the year.
The estimated number of exceedances
shall-be rounded to one decimal place (frac-
tional parts equal to O.OS round up).
The above equation may be interpreted in-
tuitively in the following manner. The esti-
mated number of exceedances is equal to
the observed number of exceedances (v)
plus an increment that accounts for Incom-
plete sampling. There were (N-n) missing
hourly values for the. year but a certain
number of these, namely z. were assumed to
be below the standard. Therefore, (N-n-z)
missing values are considered to Include pos-
sible exceedances. The fraction of measured
values that are above the level of the stand-
ard Is v/n. It is assumed that this same frac-
tion applies to the (N-n-z) misamg values
and that
1 - . (HIM)
n
of these values would have also exceeded
the level of the standard.
4. Use of multiple yean of data.—Ideally,
. the. expected number of - exceedances for a*
site would be computed by knowing the
probability that the site would record 0,1.2.3
. . exceedances in a year. Then each possi-
ble outcome could be weighted according to
its likelihood of occurrence and the appro-
priate expected value, or average, could be
computed. In practice, this type of situation
will not exist because ambient data will only
be available for a limited number of years.
Consequently, the expected number of ex-
ceedances per year at a site shall be comput-
ed, by averaging the estimated number of
exceedances for each year of available data
during the past three calendar years. In
other words, if the estimated number of ex-
ceedances- has been computed for the calen-
dar years of 1974. 1975. and 1976 then the
expected number of-exceedances is estimat-
ed by averaging those three numbers. If this
average is greater than 1. then the standard
has been exceeded at this site. It suffices to
carry one decimal place in this computation.
For example, the average of the three num-
bers 1, 1 and 2 is-1.3 which is grater than 1.
If data is-not available for each of the last
three years then this average shall be com-
puted on the basis of available data from
the remaining years in that period.
AUTHORITY: Sections 109 and 301 of the
Clean Air Act, as amended (42 U.S.C. 7409.
7601).
REFERENCES
DeLucia A. J. and W. C. Adams. "Effects
of Oi inhalation during exercise on pulmon-
ary function and blood biochemistry." J.
AppL Physiol.. Respirat. Environ. Exercise
Physiol. 43 (1): 75-81. 1977.
Hammer. D. I., V. Hasselblad, B. Portnoy,
and P. F. Wehrle. "The Los Angeles student
nurse study." Arch. Environ. Health 28: 255-
260.1974.
Hazucha, M. "Effects of ozone and sulfur
dioxide on pulmonary function in man." Ph.
D. Thesis. McGill University, Montreal,
Canada. 1973. 233 p.
National Academy of Sciences—National
Academy of Engineering. "Air Quality and
Automobile Emission Control." Report for
the 93rd Congress, 2d Session, Serial
Number 93-24. Prepared for the O.S. Senate
Committee on Public Works by the Coordi-
nating Committee on Ah- Quality Studies,
September 1974.
"Report of the UJS. House of Representa-
tives Committee on Interstate and Foreign
Commerce on the Clean Air Act Amend-
ments of 1977." HJl. Report 55-924, 95th
Congress, 2d Session, pp. 110-112.
Schoettthn. C. E. and E. Landau. "Air pol-
lution and asthmatic attacks in the Los- An-
geles area." Public Health Repts. 76 (6):
545-548. 1961.
U.S. Environmental Protection Agency.
Air Quality Criteria for Ozone and Other
Photochemical Oxidanta. Publication
Number EPA-800/8-78-004. April 1978. '
CFR Doc. 78-17153 Piled 6-21-78; 8:45 am]
[6560-01]
[40 OTU>nrt 50]
' CFRL 914-1 Docket Number OAQPS 78-8]
MEASUREMENT OF OZONE IN THE
ATMOSPHERE
Calibration of Ozone Reference Methods
AGENCY: Environmental Protection
Agency.
ACTION: Proposed rulemaking.
• SUMMARY: Appendix D to 40 CFR
Part SO prescribes a measurement
FEDERAL REGISTER, VOL 43, NO. 121—THURSDAY, JUNE 22, 1978
-------
26972
PROPOSED RULES
principle upon which reference meth-
ods for the measurement of ozone' in
the atmosphere must be based. This
appendix also specifies a procedure to
be used for calibrating those ozone ref-
erence methods. EPA now has evi-
dence that at least one other calibra-
tion procedure for ozone reference
methods is significantly more accurate
and less variable than the procedure
currently specified in Appendix D. Ac-
cordingly. EPA is proposing an amend-
the October 6, 1976, issue of FEDERAL
REGISTER (41 FR 44049), EPA pub-
lished a notice indicating that EPA
was aware of some inherent shortcom-
ings- with the NBKI procedure. In ad-
dition, the notice described evidence to
suggest that one or more alternative
calibration procedures may be superi-
or to the NBKI procedure. The notice
also indicated EPA's intention to in-
vestigate this situation by testing,
evaluating, and-soliciting public com-
ment to 40 CFR Part 50, Appendix D; ment on the alternative procedures.
to replace (supersede) the current cali-
bration procedure with the new, supe-
rior calibration procedure which is
based on ultraviolet photometry.
DATES: Comments relative to the
proposed amendment must be received
by August 18. 1978.
ADDRESS: Send comments to: Mr.
Larry J. Purdue. Department E (MD-
76). Environmental Monitoring and
Support Laboratory, U.S. Environmen-
tal Protection Agency. Research Tri-
angle Park, NC 27711.
FOR FURTHER INFORMATION
CONTACT:
Mr. Larry J. Purdue. Telephone 919-
541-3076 (FTS 629-3076).
SUPPLEMENTARY INFORMATION:
INCIDENTAL INFORMATION.
This proposal is indirectly related to
EPA's proposal to change the National
Ambient Air Quality Standard for
. photochemical oxidants (ozone) speci-
fied in 40 CFR Part 50, which appears
elsewhere in this issue of the FEDERAL
REGISTER.
BACKGROUND
Part 50 of-Title 40. Chapter I of the
Code of Federal Regulations specifies
the National Ambient Air .Quality
Standards for several air pollutants In-
cluding ozone. Appendixes to Part 50
provide information concerning the
reference methods which are used to
measure those pollutants. In particu-
lar. Appendix D to Part 50 describes a
measurement principle upon which
ozone reference methods must be
based and a calibration procedure to
be* used for calibrating such methods-.
It is the latter—the calibration proce-
dure prescribed for reference methods
for ozone—that would be changed by
the amendment being proposed
herein.
The calibration procedure presently
contained in Appendix D is based on
assay of ozone with 1% neutral buf-
fered potassium iodfde~XNBKI) and* is
known as the "NBKI procedure".- In
'The term "ozone" Is used herein, to be
consistent with another EPA action propos-
ing to substitute "ozone" for "photochemi-
cal oxidants corrected for interferences due
to nitrogen oxides and sulfur dioxide."
which is currently used In Part 50.
and to propose to revise or replace the
NBKI procedure as appropriate based
on the results of that investigation.
The amendment to 40 CFR Part 50,
Appendix D, being proposed today is a
direct result of that course of action.
Interested readers are referred to the
October 6, 1976, notice for additional
background information.
\ TESTS
The October- 6, 1976, FEDERAL REGIS-
TER notice described 3 candidate proce-
dures which were likely to be supenor
to the NBKI procedure. These were
identified as gas phase titration (OPT)
with excess, nitric oxide, ultraviolet
photometry (UV). and OPT with
excess ozone, and were set forth as al-
ternates A. B. and C, respectively, in
Attachment A to that notice. Subse-
quent to the "drafting of the notice, a
fourth promising procedure, based on
a boric- acid potassium iodide tech-
nique and identified as the "BAKI
procedure", became available.
The performance (precision and ac-
curacy) of each of these 4 procedures
jias been laboratory tested by EPA
and compared. The tests were conduct-
ed with volunteer technicians _from
both within and outside EPA. Each
volunteer was asked to become famil-
iar with and then use the procedure
being tested. The results from each
volunteer were compared quantitative-
ly to a highly stable, controlled labora-
tory reference system. Results from all
of the volunteers were then used to es-
timate the precision (variability) and
accuracy (bias) for each method.
TEST CONCLUSIONS
Interpreting the results of these
tests is difficult because of a number
of .variables which were impossible to
control. The primary uncertainty is. in-
estimating the * representativeness of
the test data to the actual perform-
ance of the procedure in real applica-
tions. Most of the procedures are de-
pendent on the accuracy and reliabil-
ity of the required equipment and ap-
paratus, and on the capability and
skill of the operator. These factors are
difficult to quantify. Nevertheless,
EPA believes certain conclusions are
valid, based on statistical and judge-
mental evaluation of the test data as
well as' information from other
sources.
Briefly,, the UV calibration proce-
dure showed very low calibration vari-
ability in the tests. Its accuracy is be-
lieved to be excellent because 'it is a
direct measurement of ozone based on
the well-established ozone absorption
coefficient. Also, independent com-
parisons of the procedure among var-
ious researchers agree within a few
percent. The other three procedures
showed considerably greater variabil-
ity in the tests than the UV procedure,
probably reflecting their relative com-
plexity and large equipment depen-
dence. While the test showed no sig-
nificant average bias for the BAKI
procedure, the two OPT procedures
were shown to have an average posi-
tive bias of 7 to 8% with respect to the
UV reference.
Additional information concerning
the test results can be obtained from a
summary report which summarizes
the test results of all four procedures.
More specific information concerning
the tests and. test results is given in
the individual test reports for each
procedure. All of these test reports can
be obtained upon request from De-
partment E (MD-78), Environmental
Monitoring and Support Laboratory,
Environmental Protection Agency. Re-
search Triangle Park. N.C.. 27711 and
will be available in a docket [Number
OAQPS 78-8] for Inspection and copy-
ing at the United States Environmen-
tal Protection Agency, Public Informa-
tion Reference Unit, Room 2922 (EPA
library). 401 M Street. Washington
D.C. 20460.
- SUMMARY OF COMMENTS RECEIVED
The October 6, 1976 FEDERAL REGIS-
TER notice specifically solicited public
comments on the three alternative
calibration procedures set forth in the
notice, and on EPA's proposed course
of action. Comments were received
from 12 respondents, representing 5
air pollution control agencies and 5 in-
dustrial organizations. While many of
the respondents recognized inadequa-
cies in the present version of the
NBKI procedure and generally sup-
ported EPA's intended course of
action, several of the respondents ex-
pressed a desire to retain the present
procedure or to adopt a modified KI
procedure demonstrated to have im-
proved accuracy and precision. In gen-
eral, these respondents indicated the
need for an inexpensive, easy to per-
form- procedure 'compatible with exist-
ing equipment. Some respondents of-
fered evidence of acceptable perform-
ance of the NBKI procedure in the re-
spondents' agency or laboratory.
Several of the respondents favored
adoption of the UV photo-metric pro-
cedure as the primary calibration pro-
cedure because it appears to be the
least complex, the most direct, and the
least operator-dependent of the alter-
native procedures under consideration.
FEDERAL REGISTER, VOL 43. NO. 121—THURSDAY, JUNE 22, 1978
-------
PROPOSED RULES
26973
The GPT procedures were generally
judged to be the least desirable alter-
natives because they are considered
too difficult to perform. There was
some concern for the reliability of the
required standards (NO standard for
GPT, 0. absorption coefficient for UV)
and the availability of the required
equipment. The effect of water vapor
and other potential interferences on
the GPT and UV procedures was also
questioned. A few of the respondents
felt that certain statements in the
notice regarding the performance of
the NBKI procedure and the consist-
ent agreement between the UV and
GPT procedures were in conflict with
the results of the various studies cited
in the notice.,
Some comments were received re-
garding the use of ozone generators
and ozone analyzers as transfer stand-
ards and the effect of atmospheric
pressure on the performance of these
devices. Several respondents showed
concern that the additional documents
cited in the notice (e.g. the Transfer
Standard Document and the Techni-
cal Assistance Documents) were not
available for public review at the time
of publication of the FEDERAL REGISTER
notice.
A more detailed summary of all of
the comments received and EPA's re-
sponse to them is available from De-
partment E at the address specified at
the beginning of this notice.
SUPERSESSION OF NBKI PROCEDURE
As noted in the October 6. 1976.
notice. EPA was aware of shortcom-
ings with the prescribed NBKI proce-
dure—substantial variability and an
apparently positive but unpredictable
bias.-The tests of the four alternate
calibration procedures confirmed
EPA's surmise that at least one of the
procedures was sufficiently superior to
the NBKI procedure to consider su-
persession. However, although accura-
cy and precision are of primary Impor-
tance, many other factors had to be
considered as well before supersession
by a new procedure could be pro-
posed—factors such as complexity.
cost and availability of equipment,
field portability, operator training.
evaluation of benefits to be obtained.
and overall impact to user agencies.
Another question was whether or not
to consider replacing the NBKZ proce-
dure by more than one new calibration
procedure to provide flexibility of
choice by users.
EPA has carefully considered all
these factors as well as all public com-
ments, and is proposing what it be-
lieves to be the optimum course of
action. The proposed changes are as
follows:
(1) Supersede the NBKI calibration
procedure with a procedure based on
UV photometry for the calibration of
reference methods for ozone. (As
noted In the October 6. 1976, notice,
no Standard Reference Material is
availabe for ozone. Hence, ozone con-
centrations established via the UV
procedure would be tantamount to pri-
mary ozone standards, and the UV
procedure itself is thus often referred
to as a "UV standard" for ozone.).
(2) Allow the independent.use of the
BAKI procedure in lieu of the UV pro-
cedure, for 18 months after promulga-.
tion of the amendment, with the rec-'
ommendation that the BAKI tech-
nique be related to a UV standard
whenever possible.
- (3) Specifically allow the use of al-
ternative procedures as transfer stand-
ards if they meet certain transfer
standard performance guidelines to be
set forth by EPA. A transfer standard
would be any device or procedure
which can be referenced to a UV ozone
standard and then used at another lo-
cation to reproduce ozone standards. A
practical transfer standard would
offer some important advantages-
such as lower cost, ruggedness. easier
operation, or convenience—over direct
use of the UV procedure.
RATIONALE FOR PROPOSED CHANGES
Of all the procedures tested, the UV
procedure clearly has the best per-
formance—low variability, high accu-
racy, and minimum operator involve-
ment. From a scientific viewpoint, it is
perhaps the most Ideal technique pres-
ently available for assaying pure ozone
concentrations below 1 ppm. While
the procedure is not without some
practical disadvantages, these appear
to be relatively few and minor, and
EPA believes they are adequately
minimized as discussed below. There-
fore, the UV procedure appears to be
the logical choice to replace the NBKI
procedure.
EPA is also convinced that the UV
procedure is the only procedure which
should be promulgated to replace the
NBKI procedure—for several reasons:
First, since no primary ozone concen-
tration standards (e.g. Standard Refer-
ence Materials) are available, the cali-
bration procedure is actually a means
for obtaining primary ozone stand-
ards. In this important respect, singu-
larity is necessary for uniformity and
comparability, and to avoid conflicts
'or discrepancies which could arise If
more than one Independent standard
were allowed. Second, none of the
other procedures can match the preci-
sion and accuracy of the UV proce-
dure. And finally, flexibility to use al-
ternate techniques is adequately—and
possibly better—provided by allowing
their use as transfer standards. As a
transfer standard, an alternative tech-
nique would have to be tested for per-
formance and related to a UV ozone
standard. Thus, accuracy would be de-
termined by the UV procedure, not
the alternative technique, and each
user would have to determine and con-
trol the variability of the technique
under his own individual conditions of
use.
The UV procedure has not been
widely used by air monitoring agencies
in the past, and many agencies are not
familiar with the procedure and may
not own a UV photometer meeting the
requirements of the procedure. Also,
the availability of UV photometers is
somewhat limited presently (a situa-
tion which should' improve shortly
after promulgation of the procedure).
In view of this situation, and in re-
sponse to a number of the public com-
ments. EPA proposes an 18-month
transition period to allow agencies to
acquire the necessary equipment,
become familiar with the UV proce-
dure, and phase it into their calibra-
tion and quality control programs.
During this 18-month period, use of
the BAKI procedure would be accept-
able until the UV procedure can be im-
plemented. The BAKI procedure is
very similar to the currently pre-
scribed NBKI procedure, and any
agency equipped for and familiar with
the NBKI procedure should have no
trouble adapting to the BAKI proce-
dure. Unfortunately, the BAKI proce-
dure shares some of the same prob-
lems associated with the NBKI proce-
dure (general variability). But the
tests showed low bias, and the variabil-
ity of the BAKI should be easier to
control because the BAKI procedure is
much less sensitive to such factors as
color development time, unpinger
typeT'and water vapor effect.
.In addition. EPA is proposing and
advocating the use of transfer stand-
ards for calibration of field-sited ozone
analyzers. Transfer standards would
have to be related to primary ozone
standards obtained by the UV proce-
dure, but would offer several impor-
tant advantages such as the following:
1. The UV calibration photometer
could be permanently located in a lab-
oratory and operated by an experi-
enced, responsible person under labo-
ratory conditions to maximize the pre-
cision and accuracy of the procedure.
This would also spare the photometer
from possible physical damage from
being moved about to field locations.
2. Agencies would have flexibility to
select a transfer standard technique or
device of their choice, and still have
comparability to the UV ozone stand-
ard.
3. Costs could be reduced by using a
single UV photometer to certify as
many transfer standards as needed by
the agency. Small agencies may even
avoid the purchase of a photometer if
they could gain access to one through
a cooperating larger agency, a State or
Regional EPA Office, an agency coop-
erative, or by commercial certification
of transfer standards.
4. Transfer standards could- be de-
signed to better survive the demands
FEDERAL REGISTER, VOL 43, NO. 121—THURSDAY, JUNE 22, 197a
-------
26974
PROPOSED RULES
of frequent transportation and field
use.
5. Transfer standards could be used
to Intel-compare UV photometers
among various agencies to assure accu-
racy.
6. Transfer standards may also be
more convenient, easier to operate.
and less expensive.
Finally. EPA emphasizes that the
proposal to supersede the NBKI proce-
dure arises more from the demonstrat-
ed superiority of the UV procedure
than from the degree of unreliability
of the NBKI procedure itself. Thus su-
persession is specifically not intended
to imply that ambient ozone measure-
ments obtained with reference (or
equivalent) methods calibrated with
the NBKI procedure are categorically
invalid or useless.
EFFECT ON NATIONAL AMBIENT Am
QUALITY STANDARD FOR PHOTOCHEMICAL
OXIDANTS
EPA believes that supersession of
the NBKI calibration procedure with
the U.V. procedure requires no revi-
sions to the oxidant standard (or pro-
posed new ozone standard) for the fol-
lowing reasons; Because of the sub-
stantial variability and unpredictable
bias in the NBKI procedure the exact
magnitude of any bias which may
exist cannot accurately be determined.
Thus no precise quantitative factor is
available for use as a basis for revision
of the standard. (For the same reason.
no factor is available to '"correct" or
"adjust" previously obtained data.)
Comparative studies cited in the Oc-
tober 6. 1978 notice suggest that the
differences between the NBKI proce-
dure and the GPT and UV procedures
generally do not exceed' 10 percent.
This degree of bias is not sufficient to
warrant revision of the standard and is
adequately accounted for within the
margin of safety included in the stand-
ard at the time of promulgation (36
FR 8186. April 30. 1971). EPA will con-
tinue to study health and other effects
related to ozone using this new cali-
bration procedure. If any evidence be-
comes available to indicate- that revi-
sion of the standard should be consid-
ered, EPA will address the issue at
that time.
EFFECT ON CURRENTLY DESIGNATED
REFERENCE AND EQUIVALENT METHODS
As noted In the October 6; 1976.
notice, replacement of the calibration
procedure specified in Appendix D of
40 CFR Part 50 would not affect the
design or performance characteristics
of existing reference methods for
ozone. Thus the only effect of the
change would be on the calibration
-procedure described in the operation
manuals associated with the analyzers.
EPA proposes to provide a reasonable
period of time—probably 6 months
after final promulgation—for manu-
facturers to revise their manuals, have
EPA approve the revised manual, and
to distribute revised manuals (or
manual supplements) to all analyzer
owners. Also, since the two equivalent
methods which have been designated
to date prescribe the NBKI calibration
procedure. EPA sees no reason why
they could not be treated in the same
way. If all manufacturers respond
promptly, there would be no impact
(other than the change in calibration
procedure Itself) to owners of desig-
nated ozone analyzers.
NEW UV CALIBRATION PROCEDURE
Unlike the currently prescribed
NBKI procedure, the new UV calibra-
tion procedure is quite simple. After
generating a stable, dynamic ozone
concentration with an ozone gener-
ator, the operator assaysJt by passing
a portion of the gas flow through the
cell of the UV photometer. The pho-~
tometer readings are then used in a
formula to calculate the ozone concen-
tration, which, as noted earlier, is ef-
fectively a primary ozone standard.
(Some photometers do the calcula-
tions automatically.) The primary
burden on the operator .is to insure (1)
that the photometer is operating cor-
rectly, (2) that the apparatus is set up
properly and is clean and leak-free.
and (3) that the calculations are accu-
rate. While none of these are particu-
larly-difficult. EPA is •preparing a
Technical Assistance Document which
will explain these tasks and provide
other detailed information about the
procedure. A draft form of this docu-
ment will be available from the ad-
dress specif led. at the beginning of this
notice.
The photometer is obviously of criti-
cal importance to the procedure and
must have a precision within 0.005
ppm or 3% of the concentration.
whichever is greater. While a calibra-
tion photometer can be assembled
from laboratory components. EPA rec-
ommends the purchase of a commer-
cial photometer which is either de-
signed- specifically for this calibration
procedure, or which can be readily
adapted to it. EPA is presently aware
of 2 such commercial photometers
(available from Dasibl Environmental
Corp.. Glendale. California, and Sci-
ence Applications. Inc.. La Jolla. Cali-
fornia) and expects others will become
available in the future.
UV photometers of the type used in
ambient ozone analyzers are likely to
be-suitable as calibration photometers.
(Conversion of an ambient UV analyz-
er to a calibration photometer Is cov-
ered in the Technical Assistance Docu-
ment mentioned above.) However, it is
important to differentiate between the
use of a UV photometer as an ambient
analyzer and its use as a calibration
photometer. This distinction is predi-
cated more on operational differences
than on any specific physical differ-
ences. EPA proposes to require that a
photometer to be used for calibration
be dedicated exclusively to such use,
be maintained under meticulous condi-
tions, and be used only with clean.
calibration gases. UV analyzers used
for ambient monitoring should always
be calibrated with an Independent cali-
bration photometer or a certified
transfer standard. A UV analyzer
should not be considered to be "self-
calibrated" even though it contains a
UV photometer which meets the speci-
fications of the UV calibration proce-
dure.
NEW BAKI CALIBRATION PROCEDURE
As noted earlier, the BAKI proce-
dure is an improved form of the cur-
rently prescribed NBKI calibration
procedure. Its independent use would
be allowed only for calibration of
ozone analyzers (not transfer stand-
ards) on a temporary basis during a
18-month transition period to permit
agencies to adopt the new. UV calibra-
tion procedure. However, the BAKI
procedure has considerable variability
and is distinctly inferior to the UV
procedure. Therefore, EPA would urge
agencies to adopt the UV procedure as
soon as practical. And, when possible,
the BAKI procedure should be related
to the UV procedure to improve the
overall accuracy.
Following the 18-month period, the
BAKI procedure would not be author-
ized for independent use, but could be
used as a transfer standard. As such, it
would have to be related to the UV
procedure, and its variability and accu-
racy would have to be monitored and
controlled. Thus agencies which find
the BAKI procedure advantageous
could continue to use this procedure
as a transfer standard.
TRANSFER STANDARDS
As indicated'earlier, EPA intends to
specifically allow transfer standards
for calibrating ozone analyzers, and
has noted a number of advantages
which might be realized by their use.
Transfer standards for ozone could in-
clude any of the alternate techniques
(GPT. BAKI) as well as devices such
as ozone analyzers and stable ozone
generators. EPA recommends that
agencies consider the use of transfer
standards where advantageous. But
transfer standards are not without pit-
falls and disadvantages of their own.
EPA is preparing a fairly comprehen-
sive guideline/Technical Assistance
Document on transfer standards for
ozone. This document is available (in
draft form), and a copy may be re-
quested by writing to the address
given for comments. If the use of
transfer standards for ozone proves to
be successful and widely accepted,
EPA intends to consider extending the
concept to SO,, NO,, and CO. Com-
FCDERAL REGISTER. VOL 43, NO. 121—THURSDAY, JUNE 22, 1978
-------
PROPOSED RULES
26975
ments on the use of transfer standards
and' on the transfer standard guideline
are welcome.
USE OF NEW PROCEDURES PRIOR TO
PROMULGATION OF AMENDMENT
As indicated in this proposal, the UV
calibration procedure—and to a lesser
extent the BAKI procedure—are be-
lieved to be scientifically superior to
the currently prescribed NBKI cali-
bration procedure. And it- is very likely
that the UV procedure (and the'BAKI
procedure on. a temporary basis) will
be promulgated to supersede the
NBKI procedure. Accordingly, agen-
cies which have the capability and.
desire to commence using these proce-
dures immediately would not be dis-
couraged from doing so. Immediate
use of transfer standards could also ba
considered on the same basis.
PUBLIC PARTICIPATION
All documents and information rele-
vant to this rulemaking are being
placed in Docket No. OAQPS 78-8* the
docket for the proposed amendments
to the standards for photochemical
oxidants. That docket will be available
for public inspection during the hours-
8:00 to 4:30 at the Public Information.
Reference Unit, Room 2922, 401 M
Street SW.. Washington. D.C.
Comments on any aspect of this pro- .
posed amendment are solicited from
interested persons or agencies. Com-
ments should be submitted to Mr.
Larry J. Purdue at the address given
at the beginning of this notice. Com-
ments should be received within 60
days of the date of publication for due,
consideration prior to final promulgar
tion. Copies of ail comments received
will be added to the docket.
In addition interested persons- may-
make comments- on the proposal orally
at the public hearing on the ozone
standard' scheduled for July 18.1978:
Dated; June ft 1OT&
DOUGLAS Cassia.
'Adottmatmtm.
It Is proposed to amend Part 50 of
Title 40, Code of Federal Regulations-
as follows:
L. Appendix D ia revised to read as
follows::
APPBMDQC. P—MUMBHEHtHNg PttBCmB AHA.
GujBR&nas PnocKDtns. FOB
KENT Of Qy""f pt tint
AUTHORITY: Section 189, sn of file CTestt
Air Act as amended (42 USC 57409. 7601).
emit light, which Is detected by a photomul-
tlplier tube. The resulting photocnrrent is
amplified and Is either read directly or dis-
played on a recorder.
2. An analyzer based on this principle win
be considered a reference method only if it
has been designated as a reference method
In accordance with Part S3 of this chapter
and calibrated as follows:
CALIBRATION PROCEDURE"
1. Principle The calibration procedure la
based on the' photometric assay of ozone
(Ot> concentrations in a dynamic flow-
system. The concentration of O, In an ab-
sorption cell Is determined from a measure-
ment of the amount of 254 nm light ab-
sorbed by the sample. This determination
requires knowledge of (1) the absorption co-
efficient (a) of O, at 254 nm. (2) the optical
path length (Z> through the sample. (3) the
transmittance of the sample at a wave-
length of 254am. and (4) the temperature
(T) and pressure (P) of the sample. The
transmittance Is defined as the ratio I/I..
when I "Is the Intensity of light which
passes through- the cell and is. sensed by the
detector when the cell contains an O,.
sample, and I. Is the Intensity of light which
passes through the cell and Is sensed by the
detector when the cell contains zero air. It is-
assumed that all conditions of the-system.
except for the contents of the absorption
cell, are Identical during measurement of I
and I* The quantities, defined above are re-
lated by the. Beer-Lambert absorption law.
TmmtniK*
(1)
UEASO
1. Ambient air and ethylene are delivered
simultaneously to a mixing zone where the
ozone in the air reacts with the ethylene to
where:
over the re-
quired concentration range.
3.4 Output manifold. The output manifold
sltould -be constructed of glass. Teflon*, or
other relatively Inert material, and should
be of sufficent diameter to insure a negligi-
ble pressure drop at the photometer connec-
tion and other output ports. The system
must have a vent designed to insure atmos-
pheric pressure In the manifold and to pre-
vent ambient air from entering the mani-
fold,
3.5 Two-way valve. Manual or automatic
valve, or other means to switch the photom-
eter flow between zero air and the Oi con-
centration.
3-.A Temperature indicator. Accurate to*
±1'C.
3.7 Barometer or pressure indicator. Accu*
-rate to ±2 torr.
4. Reagents:
4J Zero- air. The zero air must-be- free of
contaminants which would cause a detect-
able response front the O> analyzer, and it
should be. free of NO, C.H.. and other spe-
cies which react with O». A procedure for
generating suitable zero air Is given in Ref-
erence 9. As shown In figure 1. the aero air
supplied to the photometer cell- for the I.
reference measurement moat be derived
from the same source as tbe zero aiv used
- for generation.ot tbe ozone concentration to
be assayed U measasementx When, using-
the photometer to certify a. transfer stand- .
ard having its own source of ozone; see Ref-
erence 8 for guidance on meeting this re-
quirement.
FEDERAL REGBKfr, VOL «, NO. 12T—THOBWAr, JUNE 2Z 197»
-------
26976
PROPOSED RULES
5. Procedure.
5.1 General operation. The calibration
photometer must be dedicated exclusively
to use as a calibration standard. It should
always be used with clean, filtered calibra-
tion gases, and never used for ambient air
sampling. Consideration should be given to
locating the calibration photometer in a
clean laboratory where it can be stationary,
protected from physical shock, operated by
a responsible analyse, and used as a common
standard for all field calibrations via trans-
fer standards. —
5.2 Preparation. Proper operation of the
photometer is of critical importance to the
accuracy of "this procedure. The following
steps will help to venfy proper operation.
The steps are not necessarily required pnor
to each use of the photometer. Upon Initial
operation of the photometer, these steps
should be earned out frequently, with all
quantitative results or indications recorded
in a chronological record either in tabular
form or plotted on a graphical chart. As the
performance and stability record of the
photometer is established, the frequency of
these steps* may- be reduced consistent with
the documented stability of the photometer.
5.2.1 Instruction manual: Carry out all set
up and .adjustment procedures or checks as
described in the operation or instruction
manual associated with the photometer.
5.2.2 System check: Check the photometer
system for Integrity, leaks, cleanliness.
proper flowrates. etc. Service or replace fil-
ters and zero air scrubbers or other consum-
able materials, as necessary.
5.2.3 Linearity test: Test the photometer
for linearity by dilution. Generate and assay
an Oi concentration near the upper range
limit of the system (0.5 or 1.0 ppm). then ac-
curately dilute-that concentration with zero
air and reassay it. Repeat at several differ-
ent dilution ratios. Compare the assay of
the anginal concentration with the assay of
the diluted concentration divided by the di-
lution ratio, as follows-
where:
E=linearity error, percent
A.=assay of the original concentration
A,=assay of the diluted concentration
R=dilution ratio = flow of original concen-
tration divided by the total flow
The linearity error-must be less than 5%.
Since the accuracy of the measured flow-
rates will affect the linearity error as meas-
ured this way. the test Is not necessarily
conclusive. Additional information on veri-
fying linearity is contained in Reference 9.
5.2.4 Intel-comparison: When possible,
the photometer should be occasionally tn-
tercompared. either directly or via transfer
standards, with calibration photometers
used-by other agencies or laboratories.
5.2.5 Ozone losses: Some portion of the
O> may be lost upon contact with the pho-
tometer cell walls and has handling compo-
nents. The magnitude of this loss must be
determined and used to correct the calculat-
ed Oi concentration. This loss must not
exceed 5%. Some guidelines for quantita-
tively determining this loss are discussed in
Reference 9.
5.3 Assay of O, concentrations.
5 3.1 Allow the photometer system to
warm up and stabilize.
532 Adjust the flowrate through the
photometer absorpcion'cell. P., to a conve-
nient value so that the cell can be flushed In
a reasonably short penod of time (2 liter/
min is a-typical flow). The precision of the
measurements is Inversely related to the
time required for flushing, since the pho-
tometer drift error increases with tune.
5.3.3 Adjust the flowrate into the output
manifold to a value at least 1 liter/mm
greater than the total flowrate required by
the photometer and any other flow demand
connected to the manifold.
5.3.4 Adjust the flowrate of zero air. Fz.
to a value at least 1 liter/mln greater than
the flowrate required by the photometer.
535 With zero air flowing In the output
manifold, actuate the two-way valve to
allow the photometer to sample first the
manifold zero air. then Ft. The two photom-
eter readings must be equal (1 = 1.).
NOTE: In some commercially available
photometers, the operation of the two-way
valve and various other operations in sec-
tion 5 3 may be earned out automatically by
the photometer.
5.3.6 Adjusfthe O> generator to produce
an Oi concentration as needed.
5.3.7 Actuate the two-way valve to allow
the photometer to sample zero air until the"
absorption cell Is thoroughly flushed and.
record the stable measured value of I..
5.3.8 Actuate the two-way valve to allow
the photometer to sample the ozone concen-
tration until the absorption cell is thor-
oughly flushed and record the stable meas-
ured value of I. '
5.3.9 Record the temperature and pres-
sure of the sample in the photometer ab-
sorption cell. (See Reference 9 for guid-
ance.)
5.3.10 Calculate the O» concentration
from equation 4. An average of several de-
terminations will provide better precision.
where:
COj]0uT=O, concentration, ppm
a=absorption coefficient of O, at 254
nm=308 atm'1 cm'1 at 0"C and 760 torr
2=optical path-length, cm
T=sample temperature. K
P=sample pressure, torr
L=correction factor for O, losses from
5.2.5= concentration and the cor-
responding analyzer response. If substantial
adjustment of the span control is necessary.
recheck the zero and span adjustments by
repeating steps 5.5.2 to 5.5.4.
5.5.5 Generate several other O, concen-
tration standards (at least 5 others are rec-
ommended) over the scale.range of the O>
analyzer by adjusting the O, source or by
Option 1. For each O, concentration stand-
ard, record the Oi concentration and the
corresponding analyzer response.
5.5.6 Plot the O> analyzer responses
versus the corresponding O> concentrations
and draw the O, analyzer's calibration curve
or calculate the appropriate response factor.
5.5.7 Option 1. The various O, concentra-
tions required in steps 5.3.11 and 5'5.5 may
be obtained by dilution of the O, concentra-
tion generated in steps 5.3.6 and 5 5.3. With
this option, accurate flow measurements are
required. The dynamic calibration system
must be modified as shown in Figure 2 to
allow for dilution air to be metered in down-
stream of the O, generator. A-tmxing cham-
ber between the Oi generator and the
output manifold is also required. The flow-
rate through the O, generator (F0) and the
dilution air flowrate (F0) are measured with
a reliable flow or volume standard traceable
to NBS. Each O» concentration generated by
dilution is calculated from:
A-
where:
FEDERAL REGISTER, VOL 43, NO. 121—THURSDAY, JUNE 22, 1978
-------
PROPOSED RULES 26977
[O,]'our=cliluted O, concentration, ppm 3.-W. B. OeMore and O. Raper, "Hartley J. W. Simons. R. J. Paur, H. A. Webster.
F0=flowrate through the O, generator. Band Extinction Coefficients of Ozone in and E. J. Bair. "Ozone Ultraviolet Photoly-
llter/mln the Gas Phase and In Liquid Nitrogen. sis. VI. The Ultraviolet Spectrum". J-. Ctiem.
Po = diluent air flowrate. liter/min Carbon Monoxide, and Argon". J. Phya. Phya., 59, 1203 (1973).
1.EC.Y. inn and Y. Tanaka. "Absorption
Coefficient of Ozone In the Ultraviolet and 5. K. H. Becker. U. Schurath. and H. Seitz. s.i'. v
Visible Regions". J. Opt Soc. Am., 43. 870 "Ozone Olefin Reactions in the Gas Phase Kesearen inangie rars. «.c.
(1953). 1. Rate Constants and Activation Energies", 9. "Technical Assistance Document for
2. A. G. Hearn. "Absorption of Ozone In IntT. Jour, of Chen. Kinetics, VI. 725 (1974). the Chemiluminescence' Measurement of
the Ultraviolet and Visible Regions of the 6. M. A. A. Clyne and J. A. Coxom. "Kinet- Ozone". EPA Publication available in draft
Spectrum". Proc. Phya. Soc. (London). 78, ic Studies of Oxy-halogen Radical Systems". form from EPA. Department E (MD-76).
932 (1961). Proc. Roy. Soc.. A303. 207 (1968). Research Triangle Park. N.C. 27711.
FEDERAL REGISTER, VOL 43, NO. 121—THURSDAY, JUNE 22, 1978
-------
26978
PROPOSED RULES
ZERO
•in
FlOW
CONTROLLER
F»
Oj
GENERATOR
OUTPUT
MANIFOLD
•VENT
TO INIET OF ANALYZER
UNDER CALIIRATION
EXTRA OUTLETS CAPPED
WHEN NOT IN USE
OPTICS
SOURCE
o I
•EXHAUST
Figure 1 Schematic diagram of a typical UV photometric calibration system
EXTRA OUTLETS CAPPED
WHEN NOT IN USE
-VENT
—— ;..»«?."» — PUMP —--EXHAUST
. Figure 2 Schematic diagram of a typical UV photometric calibration system (OPTION 1)
, VOL 4X NO. Ml—THUBSDAY. JUNE 2fc 197»
-------
PROPOSED RULES
26979
Temporary Alternative Calibration Proce-
dure—(Boric Acid-Potassium Iodide). This
procedure may be used as an alternative to
the Ultraviolet Photometry procedure for
direct calibration-T>r ozone analyzers—but
not to certify transfer standards—until [18
months after the date of final promulga-
tion]. After that time this procedure can be
used only as a transfer standard in accord-
ance with the guidance and specifications
set forth in Reference 4. "Transfer Stand-
ards for Calibration of Ambient Air Moni-
toring Analyzers for Ozone".
1. Principle. This calibration procedure (1)
is based upon the reaction between ozone
(Oi) and potassium iodide (KI) to release
iodine (I,) according to the stoichiometiic
equation: (2)
O,+2I-+2H*-I.+H,O+O,
(1)
The stolchiometry is-such that the amount
of I. released is equivalent to the amount of
O> absorbed. Ozone is absorbed In a 0.1M
boric acid (HJ3O.) solution containing 1%
KI, and the I> released la measured
spectrophotometrically as the trllodide Ion
(!••> at a wavelength of 352 nm. The output
of a stable O, generator Is assayed In this
manner, and the generator Is immediately
used to calibrate the O, analyzer. The O,
generator must be used immediately after
calibration and without physical movement.
and It is recalibrated prior to each use. Al-
ternatively, the O> analyzer may be calibrat-
ed by assaying the O, concentrations using
the prescribed procedure while simulta-
neously measuring the corresponding Ot
analyzer responses. Ozone concentration
standards may also be generated by an op-
tional dilution technique. With this option.
the highest O, concentration standard Is as-
sayed using the prescribed procedure. The
additional O, concentration standards re-
quired are then obtained by dilution.
2. Apparatus. Figures 1'and 2 Illustrate a
typical BAKI O, calibration system and
show the suggested configuration of the
components listed"below. All conneatlons be-
tween components downstream of the Oi
generator should be of glass. Teflon* or
other relatively inert material.
2.1 Air flow controller. Device capable of
maintaining a constant air flowrate through
the O> generator within ±2%.
2.2 Air flowmeter. Calibrated flowmeter
capable of measuring and monitoring the
air flowrate through the Oi generator
witlun-±2%.
2.3 Ozone generator. Device capable of
generating stable levels of Oi.over the re-
quired concentration range.
. 2.4 Output manifold. The output mani-
fold should be constructed of glass. Teflon*.
or other relatively inert material and should
be of sufficient diameter to Insure an negli-
gible pressure drop at the analyzer connec-
tion. The system must have a vent designed
to Insure atmospheric pressure In the mani-
fold and to prevent ambient air from enter—.
ing the manifold. . '
2.S Implngers: All glass Imp'lngers witbT
the specifications indicated In Figure 2 are
recommended. The unpingers may be pur-
chased from most major glassware suppli-
ers. Two unpingers connected In series are
used to Insure complete collection of the
sample.
2.6 Air pump and flow controller. Any
pump, and flow control device capable of
maintaining a constant flowrate of 0.4-0.6
liter/nun through the unpingers may be
used. A critical orifice as described by Lodge
et aL (3) Is recommended. The orifice should
be protected against moisture and particu-
late matter with a membrane (flier or mois-
ture trap containing Drterite", silica gel. or
glass wool. The air pump must be capable of
maintaining a pressure differential of at
least 0.6-0.7 atmospheres across the critical
orifice. Alternatively, a needle valve could
be used with the pump to adjust the flow
through the Impingers. A flowmeter is then
recommended to monitor the flow. The
needle valve-flowmeter combination should
be protected against moisture and panicu-
late matter with a membrane filter or mois-
ture trap.
2.7 Thermometer. Accurate to ±TC.
2.8 Barometer. Accurate to ±2 torr.
2.9 Volumetric flasks (Class A). 25, 100,
200, 1000-mL
2.10 Plpets (Class A). 1. 2, 3. 5. 10. 15, 20.
and 25-ml-volumetric.
2.11 Spectrometer. Capable of measuring
absorbance at 352 nm with an absolute accu-
racy of ±1% and linear response over the
range of 0-1.0 absorbance units. The photo-
metric accuracy may be checked using opti-
cal glass filters which have certified absor-
bance values at specified wavelengths.
Matched 1-cm or 2-cm cells should be used
for all absorbance determinations.
3. Reagents.
3.1 Zero air. The zero ait must be free of
contaminants which will cause a detectable
response on the O. analyzer or which might
react with 1% BAKI. Air meeting this re-
quirement may be obtained by: (1) passing it
through silica gel for drying: (2) treating it
with Oi to convert any nitric oxide (NO) to
nitrogen dioxide (Nd); (3) passing it
through activated charcoal (6-14 mesh) and
molecular sieve (6-16 mesh, type 4A) to
remove any NO,, hydrocarbons, and traces
of water vapor and (4) passing it through a
2-micron filter to remove any partlculate
matter. v
3.2 Boric add (B^BO,). ACS reagent grade.
3.3 Potassium iodide (KI), ACS reagent
grade.
3.4 Hydrogen peroxide (H.O.). ACS rea-
gent grade. 3% or 30%.
3.5 Potassium lodate (Kid). ACS reagent
grade, certified 0.1N.
3.6 Sulfuric acid (H£O.>. ACS reagent
grade. 95% to 98%.
3.7 Distilled water. Used^for preparation .
of all reagents.
3.8 Absorbing reagent. Dissolve 6.2 g of
boric acid (HUBOi) in approximately 750 ml
of distilled water In a nonactinometric 1000-
ml volumetric flask. The flask, may be
heated gently to speed dissolution of the
HiBO* but the solution must then be cooled
to room temperature or below before pro-
ceeding 'With the reagent preparation.
CWhile the HiBOt solution is cooling, pre-
pare the hydrogen peroxide (H,O,; solution
according to the directions in 3.9.1 When
• the H»BO. solutlonhaa cooled, add 10 g of
potassium Iodide (KI) to the BUBO, solution
and dissolve. Add 1 ml of 0.0018% H,O. solu-
tion (see 3.9) and mix -thoroughly. Within 5
minutes after adding the peroxide, dilute to
volume with" distilled water, mix. and deter-
mine the absorbance of this BAKI solution
at 352 nm against distilled water as the ref-
erence. The pH of the BAKI solution must
be 5.5x0 2.
Set the absorbing solution aside for 2
hours and then redetemune the absorbance
at 352 nm against distilled water as the ref-
erence. If the resultant absorbance from
this second determination is at least 0.010
absorbance units/cm greater than the first
determination, the absorbing reagent is
ready for use. If no increase or an Increase
of less than'03) 10 absorbance units/cm is ob-
served, the KI reagent probably contains an
excessive amount of a reducing contaminant
and must be discarded. In this event, pre-
pare fresh absorbing reagent using a differ-
ent numbered lot of KI. If unacceptable ab-
sorbing reagent results from different lots
of KI, test the possibility of contamination
in the H>BOi by using a different numbered
lot of BUBO,.
3.9 Hydrogen peroxide solution (0.0018%-).
Pipet 3 ml of 30% or 30 ml of 3% hydrogen
peroxide (H,O.) into approximately 200 ml
of distilled water in a 1000-ml volumetric
flask, dilute to volume with distilled water.
and mix thoroughly. To prepare the
0.0018% solution, pipet 2 ml of the above so-
lution Into 50 ml of distilled water in a 100-
ml volumetric flask, dilute to volume with
distilled water, and mix thoroughly. This
0.0018% HjOi solution must be prepared
fresh each time a fresh batch of absorbing
reagent is prepared. Therefore, the remain-
Ing contents of both volumetric flasks
should be discarded after treatment of the
BAKI absorbing reagent (see 38).
3.10 Standard potassium tcdate solution
(0.1N). Use a commercial standard solution
of potassium lodate > having a certi-
fied normality.
3.11 Sulfunc add (IN). Dilute 28 ml of
concentrated (95-98%) sulfuric acid (H,SO.>
to volume In a 1000-ml volumetric flask.
4. Procedure.
4.1 Assemble an ozone calibration system
such as shown in Figure 1.
4.2 Assemble the KI sampling train such
as shown in Figure 2. All connections be-'
tween the various components must be leak
tight and may be made using grease-free.
ball Joint fittings, heat-shrtnkable Teflon"'
tubing, or Teflon* tube fittings. The connec-
tion to the O> output manifold should be
made using 6 mm (1/4 in.) Teflon" tubing
not to exceed 1.5 meters in length.
4.3 Calibrate all flowmeters and critical
orifices under the conditions of use against
a reliable flow or volume standard such as a
NBS traceable bubble flowmeter or wet-test
meter. Correct all volumetric flowrates to
25'C and 760 torr as follows:
>S - "HZO
r, • f« • •
. where:
F,=flowrate corrected to reference condi-
tions (25* C and 760 torr), liter/nun
F,=flowrate at sampling conditions, liter/
nun
Pi=barometric pressure at sampling con-
ditions, torr
PBW=vapor pressure of R, at T9. torr (For
wet volume standard. For a dry stand-
ard. PTO=0)
Tj=temperature at sampling conditions.
•C
4.4 KI calibration curve.
4.4.1 Prepare iodine standards, fresh
when needed, as follows:
A. Accurately pipet 10 ml of 0.1N standard
potassium lodate
-------
26980
PROPOSED RULES
acid (H.SO.). dilute to volume with distilled
water, and mix thoroughly.
B. Immediately before use. plpet 10 ml of
the iodine (I,) solution prepared in step A
above Into a 100-ml volumetric flask and
dilute to volume with absorbing reagent.
Then further dilute this solution by pipet- •
ting 10 ml of it into a 200-ml volumetric
flask and diluting it to- volume with absorb-
ing reagent.
C. In turn, pipet 5. 10. 15. 20. and 25 ml
aliquots of the final !• solution prepared in
step B above into a senes of 25-ml volumet-
ric flasks. Dilute each to volume with ab-
sorbing reagent and mix thoroughly. To
prevent I, losses by volatilization, the flasks
should1 remain stoppered until absorbance
measurements are made. Absorbagce mea-
surements (see 4.4.2) should be taken within
20 minutes after preparation of the I> stand-
ards.
4.4.2 Determine the absorbance of each
I, standard at 352 run. Also measure the ab-
sorbance of a sample of unexposed absorb-
ing reagent. Determine the net absorbance
of each I, standard as:
/ tuoli'
• IIHOrMM
. • LJSWSM,J
4.4.3 For each T, standard, calculate the
net absorbance/cm as:
Mt .norwu/c. .' Mt »..r«.nc. (<)
where:
bispectrophotometer cell path length, cm
4.4.4 For each I. standard, calculate the
It concentration in mole/liter as;
or.
[Wi=NI,i,xV,xlO-i
<5b)
where:
(Iili=concentration of each Ii standard.
mole It/liter
NMO>=normality of K3O, (from 3.10). eq-
liter
V,=volume of !• solution (from step
4.4.1.0=5, 10.15. 20. or 25 ml
4.4.5 Plot net absorbance/cm (y-axis)
versus the mole I,/liter (x-axis) for each I,
standard and draw the KI calibration curve.
Calculate the slope of the curve In liter
mole-' cm-' and record as S* The value of
the slope should be 25.800±600. If the slope
Is not within this range, and .the photomet-
ric accuracy of the spectrophotometer
meets the specifications given in 2.11. repeat
the procedure using freshly prepared !•
standards. If the slope is still not within the
specified range, repeat the procedure using
a different lot of certified 0.1N KIO. to pre-
pare the Ii standards.
4.5 Calibration of the ozone generator.
4.5.1 Adjust the air now through the O,
generator to the desired flowrate and record
as P.. At all times the air flow through the
generator must be greater than the total
flow required by the sampling systems, to
assure exhaust flow at the vent.
4.5.2 With the O, generator off. flush the
system with zero air (or at least 15 minutes
to remove residual O* Pipet 10 ml of absorb-
ing reagent Into each of 2 Impingers and
connect 'them into the sampling train as
shown in Figure 2. Draw air from the
output manifold of the O, calibration
system through the sampling train at 0.4-
0.6 liter/mm for 10 minutes. Immediately
transfer the exposed solutions to- clean spec-
trophotometer cells. Determine the net ab-
sorbance (sample absorbance-unexposed
reagent absorbance) of each solution at 352
ran within three minutes. Add the net ab-
sorbances of the two solutions to obtain the'
total net absorbance. Calculate the indicat-
ed Oi concentration (system blank) as equiv-
alent O> concentration according to 4.5.4. If
the system blank is greater than 0.005 ppm
CX. continue flushing the O, generation
system for an additional 30 minutes and re-
determine the system blank. If the system
blank is still greater than 0.005 ppm Cs. the
zero air probably contains traces of an oxi-
dizing contaminant, and the activated char-
coal'and molecular sieve (see 3.1) should be
replaced.
4.5.3 Adjust the Oi generator to-generate
an Oi concentration in the range of interest
and allow the system to equilibrate for
about 15 minutes. The uncalibrated O, ana-
lyzer to be calibrated can conveniently be
used to indicate the stability of the O, gen-
erator output. When the O, generator
output has stabilized, pipet 10 ml of absorb-
ing reagent into each unpinger. Draw O,
from the output manifold of'the O» calibra-
tion system through the sampling train at
0.4-0.6 Uter/mln. Use a sample time of be-
tween 10 and 30 minutes such that a total
net absorbance between 0.1 and 1.0 absor-
bance units is obtained. (At an O, concentra-
tion of 0.1 ppm and a sampling rate of 0.5
liter/mln. a total net absorbance >0.1 absor-
bance units should be obtained if a sampling
time of 20 minutes and 1-cm spectrophoto-
meter cells are used.) Immediately after col-
lection, transfer the exposed solutions to
clean spectrophotometer cells. Determine
the net absorbance (sample absorbance—un-
exposed reagent absorbance) of each solu-
tion at 352 run within three minutes. Add
the net absorbances of the two solutions to
obtain the total net absorbance.
4.5.4. Calculation of ozone concentration.
4.5.4.1 Calculate the total volume of air
sampled, corrected to reference conditions
of 25'C and 760 torr as:
4.5.4.2 Calculate the I, released in moles
as:
V.=F.xt,
where:
DDK I,
UUl Mt
-------
Record the O> concentration and the O»
analyzer response. II substantial adjustment
of the span control is necessary, recheck the
zero and span adjustments by repeating'
steps 4.6.2 through 4.8.4.
4.6.5 Generate several other O> concen-
trations (at least 5 others are recommended)
over the scale range of the O. analyzer by
adjusting the O, generator settings (prefer-
ably the same settings as used In 4.5) or by
Option 1. For each O, concentration, allow
for a stable analyzer response, then record
the response and the corresponding O> con-
centration.
4.6.6 Plot the Or analyzer responses
versus the corresponding O> concentrations
and draw the O, analyzer's calibration curve
or calculate the appropriate response factor.
4.6 7 Option 1: The various O, concentra-
tions required in step 4.6.5 may be obtained
by dilution of the O, concentration generat-
ed In 4 6.3. With this option, accurate flow
measurements are required. The dynamic
PROPOSED RULES
calibration system must be modified as
shown in Figure 3 to allow for dilution air to
be metered in downstream of the O, gener-
ator. A mixing chamber between the O, gen-
erator and the output manifold is also re-
quired. The flpwrate through the O> gener-
ator (F0> and the dilution air flowrate (PD)
are measured wjth a reliable flow or volume1
standard traceable to NBS. The highest O>
concentration standard required (80% URL)
Is assayed according to the procedure In 4.5.
Each Oi concentration generated by dilu-
tion Is calculated from:
(11)
v^'
where: COJ'our = diluted Oi concentration.
ppnv F. = flowrate through the O, gen-
erator, liter/nun; F0 = diluent air flow-
rate, llter/mln.
NOTE.—Direct calibration of the O, analyz-
er may also be accomplished by assaying the
26981
O, concentrations using the procedure in 4.5
while simultaneously measuring the corre-
sponding Oi analyzer responses as specified
in 4.6.
REFERENCES
1. D. L. Plamm, "Analysis of Ozone at Low
Concentrations with Boric -Acid Buffered
KI," Environ. Sa.-TechnoL, 11. 978 (1977).
2. B. E. Saltzman and N. Gilbert. "lodome-
tric Mlcrodeternunation of Organic Oxi-"
dants and Ozone." AnaL Chem., 31, 1914
(1959). ' -
3. J. P. Lodge. Jr.. J. B. Pate. B. E.
Ammons. and G. A. Swanson. "The Use of
Hypodermic Needles as Critical Orifices in
Air Sampling." J. Air Poll Control Assoc.,
16, 197(1966).
4. "Transfer Standards for Calibration of
Ambient Air Monitoring Analyzers for
Ozone." EPA Publication available in draft
form from EPA. Department E (MD-T8).
Research Triangle Park. N.C. 27711.
FEDERAL. REGISTER. VOL 43, NO. Ml—THURSDAY, JUNE 22. 1978
-------
26982
PROPOSED RULES
O*
ZERO
AIR
FLOW
CONTROLLER
FLOWMETER
fQ ^
•
03
GENERATOR.
OUTPUT
MANIFOL-D
VENT
i.r
EXTRA OUTLETS CAPPED
WHEN NOT IN USE
TO INLET OF
Kl SAMPLING TRAIN
TOINLETOF ANALYZER
UNDER CALIBRATION
Fiqure 1 Schematic diayram of a typical BAKI calibration system
FEDERAL REGISTER, VOL 43. NO. 121-THURSDAY, JUNE 22. 1978
-------
PROPOSED RULES
26983
HYPODERMIC
NEEDLE
CRITICAL ORIFICE FLOW CONTROL
TO AIR
PUMP
Smml.D.-^ [«-
1
1
i
E
r-
^
<
(
9
i
a
a
3
3
/
u
M
m
•»
>
fi h — — •
INSIDE 25mm
CLEARANCE 0.0.
3 TO 5 mm
*—
1
/ ——*> T0A|R
|j—IAr~ PUMP
NEEDLE VALVE
_L
T
10 mm 0.0
f FLOWMETER
? 24/40, CONCENTRIC WITH
OUTER PIECE AND WITH
NOZZLE
GRADUATIONS AT 5-ml
INTERVALS. ALL THE
WAY AROUND
NOZZLE I.D. EXACTLY
1mm; PASSESO.09TOO.il
dm AT 12 in. H20 VACUUM.
PIECES SHOULD BE INTER-
CHANGEABLE, MAINTAINING
NOZZLE CENTERING AND
CLEARANCE TO BOTTOM
INSIDE SURFACE
ALTERNATE FLOW CONTROL
ALL GLASS MIDGET IMPINGER (THIS IS A COMMERCIALLY
STffCKED ITEM).
Figure 2. Kl sampling train.
KDHAL REOISra, VOL 43, NO. 171— THURSDAY, JUNE 2Z 1971
-------
26984
o
PROPOSED RULES
F0
03
GENERATOR
MIXING
CHAMBER
VENT
OUTPUT
MANIFOLD
i
i
u V 'i
H
WHEN NOT IN USE
TO INLET OF-
Kl SAMPLING TRAIN
TO INLET OF ANALYZER
UNDER CALIBRATION
Fiqure 3 Schematic ciiaqranvof a typical BAKI calibration system (Option 1)
[PR Doc. 78-17154 Filed 6-21-78: 8.45 am]
FCDHtAL REGISTER. VOL 43. NO. 121—TNURSOAY, JUNE a, 1979
-------
PROPOSED RULES
26985
[6560-01]
CFRL 914-2]
[40 CFR Part* 51 and 52]
REQUIREMENTS FOR PREPARATION. ADOP-
TION, AND SUBMITTAL OF IMPLEMENTA-
TION PLANS
Approval and Promulgation of Implei
Plan.
irtatld
AGENCY: Environmental Protection
Agency.
ACTION: Proposed rule.
SUMMARY: In this action, the Ad-
ministrator proposes _ to make certain
revisions to the procedures for prepa-
ration of State Implementation Plans
for photochemical oxidants. Specifi-
cally, he proposes the following ac-
tions:
1. Change the terms "photochemical
oxidant(s)" and "oxidant(s)" to
"ozone" throughout Parts 51 and 52.
2. Delete Appendix J of 40 CFR Part
51 and revise 40 CFR 51.14 with re-
spect to the method for calculating
needed reductions in hydrocarbon
emissions.
The terms "photochemical oxi-
dants" and "oxidants" are being
changed to "ozone" to be consistent
with EPA's proposal to redesignate
the photochemical oxidants standard
as an ozone standard. The redesigna-
tion of the standard, along with the
reasons for it. will be proposed as a
separate FEDERAL REGISTER action.
Thoughout the rest of these actions
the word "ozone" will be used in place
of "oxidant". except when reference Is
made to existing language in the Code
of Federal Regulations.
Appendix J Is being deleted to make
the Part 51 regulations consistent with
EPA's current policy on development
of State Implementation Plans (SIPs)
to meet the ozone standard. States will
be allowed to use any of four pre-
scribed techniques to relate ozone con-
centrations to hydrocarbon emissions.
The techniques will be set forth In the
proposed revisions to 40 CFR
51.14(0(4).
DATES: Comments must be received
by August 18. 1978. Comments submit-
ted will facilitate internal distribution
and public availability.
ADDRESSES: Persons may submit
written comments on this proposal to:
U.S. Environmental Protection
Agency. Office of Air Quality Plan-
ning and Standards, Control Programs
Development Division (MD 15), Re-
search Triangle Park. N.C. 27711. At-
tention: Mr. Darryl D. Tyler.
EPA will make all comments re-
ceived within 30 days of publication of
this proposal available for public in-
spection during normal business hours
at: EPA Public Information Reference
Unit, 401 M Street, SW.. Room 2922,
Washington. D.C. 20460.
FOR FURTHER INFORMATION
CONTACT:
Joseph Sableski, Chief Plans Guide-
lines Section, Control Programs De-
velopment Division (919-541-5437).
SUPPLEMENTARY INFORMATION
In connection with the review of the
NAAQS and associated SIP require-
ments for ozone, EPA has determined
that certain changes in 40 CFR Part
51 are appropriate.
APPENDIX J
Petitions to EPA from- the American
Petroleum Institute (and 29 member
companies) on December 9, 1976, and
the City of Houston on July 11. 1977.
recommended revisions to the method
of calculating needed hydrocarbon re-
ductions specified in Appendix J. EPA
has studied various methods by which
these calculations can be made and
has determined that Appendix J of 40
CFR 51 no longer represents the only
acceptable analytical relationship be-
tween hydrocarbons and ozone. There-
fore, Appendix J is being proposed for
deletion.
SECTION 51.14
The Administrator is also proposing
to, amend 40 CFR 51.14(0(4) to allow
the use of alternate analytical rela-
tionships for' determining the hydro-
carbon reductions necessary to meet
the ozone standard. EPA is conducting
further studies and will propose alter-
. natives or a replacement for Appendix
J when the studies are concluded.
During the interim period, for the pur-
poses of SIP control strategy develop-
ment, any one of four modeling tech-
niques may be used. EPA has pub-
lished a document entitled. "Uses,"
Limitations and Technical Basis of
Procedures for Quantifying Relation-
ships Between Photochemical Oxi-
dants and Precursors" (November.
1977; EPA 450/2-77-02 la) which refer-"
ences analytical techniques that
States must consider. These tech-
niques include the following:
(1) Photochemical grid models—
These models are based on the most
accurate available physical and chemi-
cal principles underlying the forma-
tion of ozone.
(2) Empirical Kinetics Modeling Ap-
proach (EKMA>—This model repre-
sents a compromise between rigorous
treatment - of chemical and physical
principles underlying the formation
and dispersion of ozone and the exten-
sive data requirements necessary to
represent such principles in model
form. EKMA is not as accurate or
flexible as the grid models. However. It
does reflect reality to a greater extent
than the empirical and statistical ap-
proaches.
(3) Empirical and Statistical
Models—These models reflect observer
relationships between ozone and other
variables. However, they do not imply
cause-effect relationships; hence, their
applicability to estimating the impact
of substantial control programs is lim-
ited because the conditions, under
which the relationships in the model
have been derived, will be altered by
control programs.
(4) Proportional Rollback—This
model assumes a linear relationship
between hydrocarbon emissions and
ambient concentrations of ozone. Pro-
portional rollback appears to be useful
as a lower bound for estimates of hy-
drocarbon controls needed to attain
the ozone standard in most U.S. cities.
EPA will also make available com-
puter programs and other aids to
enable States to use the techniques de-
scribed above.
Background concentrations and
transport of ozone from upwind loca-
tions can impact upon high levels of
ozone in or near an urban area during
afternoon hours. Therefore, considera-
tion of background and transport
should be made in applying any of the
techniques to develop an ozone control
strategy. Means for measuring trans-
ported ozone and interpreting the
measurements, as well as procedures
for assessing the impact of transport
in an urban area are described in the
EPA document referenced above. In
developing the ozone control strategy
for a particular area. States may
assume that the ozone standard will
be attained at upwind locations.
IMPACT
In accordance with Agency policy as
set forth in 39 FR 37419. EPA has re-
viewed the proposed changes and de-
termined that they do not constitute
"significant" "revisions or modifica-
tions (as defined in 39 FR 37419) and
therefore do not require an environ-
mental impact statement.
Dated: June 9,1978.
DOUGLAS M. COSTLE,
Administrator.
In Title 40. Chapter I. EPA proposes
to amend Subchapter C as follows:
PART 51—REQUIREMENTS FOR PREPARATION.
ADOPTION, AND SUBMITTAl OF IMPLEMEN-
TATION PLANS
1. Wherever the terms "Photochemi-
cal oxidanUs)" or "oxidant(s)" appear
in Part 51. they are changed to-read
"ozone."
2. Appendix J is deleted and re-
served.
3. Section 51.14(0(4) is revised to
read as follows:
FEDERAL REGISTER. VOL 43, NO. 121—THURSDAY. JUNE 22. 1978
-------
26986
§51.14 Control strategy: Carbon monox-
ide, hydrocarbons, photochemical oxi-
dants, and nitrogen dioxide.
(c)
• • • • •
(4) In selecting an appropriate model
to determine the amount of hydrocar-
bon reductions ^necessary to demon-
strate attainment of the ozone stand-
ard, one of the following techniques
must be applied:
(i) Photochemical grid models—
These models are based on the most
accurate available physical and chemi-
cal -principles underlying the forma-
tion of ozone.
PROPOSED RULES
(ii) Empirical Kinetics Modeling Ap-
proach (EKMA>—This model repre-
sents a compromise between rigorous
treatment of chemical and physical
principles underlying ozone formation
and dispersion and the extensive data
requirements that would be necessitat-
ed by- such art approach.
(ill) Empirical and- Statistical
Models—These models reflect observer
relationships between ozone and other
variables.
"(iv) Proportional Rollback—This
model assumes a linear relationship
between hydrocarbon emissions- and
ambient concentrations of ozone.
In developing ozone control strate-
gies for a-particular area, background
concentrations and ozone transported
into an- area must be considered.
States may assume that the ozone
standard will be attained in upwind
areas.
PART 52—APPROVAL AND PROMULGATION
OF IMPLEMENTATION PLANS
4. Wherever the terms "photochemi-
cal oxidant(s)" or "oxidant(s)" appear
in Part 52, they are changed to read
"ozone".
AUTHORITY: Sections 110 and 301(a). Clean
Air Act. as-amended (42 U.S.&-9410. 7601).)
(PR Doc. 78-17155 Filed 6-21-78: 8:45 am]
FORM. RCQUTfX. VOL. 4& NO; 1«—THURSDAY. JUKI 7Z I97»
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TAB E
021740
DRAFT - October 12, 1978
(Through IV-F-40 and IV-D-122)
STAFF REPORT
REVIEW OF PUBLIC COMMENTS CONCERNING PROPOSED REVISION OF
THE NAAQS FOR PHOTOCHEMICAL OXIDANTS
Washington, D.C. , July 18, 1978
Atlanta, GA, August 17, 1978
Dallas, TX, August 22, 1978
Los Angeles, CA, August 24, 1978
Prepared by
PEDCo Environmental, Inc.
11499 Chester Road
Cincinnati, Ohio 45246
Contract No. 68-02-2515
Task No.
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Pollutant Strategies Section of
Strategies and Air Standards Division
October, 1973
Environmental
Protection Agency
p^Tinn 0
DEC 20 197P
LIBRARY
-------
Review of Public Comments Concerning
Proposed Revision of the NAAQS for Photochemical Oxidants
Summer 1978
1.0 INTRODUCTION
EPA has conducted a review of the criteria upon which the existing
primary and secondary photochemical oxidant standards are based. The
revised criteria have been published (EPA-600/8-78-004, Volumes I and
II, April 1978) and the proposed revision to the standard appeared in
the Federal Register on June 22, 1978 (Vol. 43, No. 121, pp 26962-
26986). The Federal Register announcement included a preamble which
identified supporting information used by the EPA in developing the
proposed standard, and supplementing information pertinent to the proposal,
The existing primary and secondary standards for photochemical
oxidants are currently set at 0.08 ppm, 1-hour average not to be exceeded
more than once per year. As a result of the review and revision of
health and welfare criteria, EPA has proposed to raise the primary
standard level to 0.10 ppm, 1-hour average. EPA also has proposed that
the secondary welfare-based standard remain at 0.08 ppm, 1-hour average.
Other changes proposed include: (1) changing the chemical desgination
of the standard from photochemical oxidants to ozone, and (2) changing
to a standard with a statistical rather than deterministic form, i.e.
allowable exceedances will be stated as an expected value, not an explicit
value.
1-1
-------
During the period between the June 22 proposal announcement and
final promulgation of the standard, EPA will continue its examination of
health and welfare criteria and seek to further involve the public and
other affected parties in the final decision on the air quality standard.
Public hearings regarding the proposal were held at Washington,
D.C., on July 18, 1978, at Atlanta, GA, on August 17, 1978, at Dallas,
TX, on August 22, 1978, and at Los Angeles, CA, on August 24, 1978.
Written comments on the proposed revision are due on or before September
24, 1978.
Section 2.0 of this report is an outline and summary of specific
issues discussed in the oral presentations in the hearings and of written
comments received.
Section 3.0 is a general overview and summary of the presentations
and written comments outlined in Section 2.0.
In the document notation the IV-F- series are transcripts and
written materials from the hearings; the IV-D- series are other written
materials supplied relative to the proposed standard.
1-2
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2.0 Outline of Key Issues
I. Summary of Comments on Level of Standard
A. Primary standard
1. Endorse current standard level, 0.08 ppm
Rauch, EOF, IV-F-1, p.15 (Any doubt, resolve in favor
of current standard.)
Wilber, Concerned citizen, Broomfield, CO, IV-D-1
Leven, Concerned citizen, Walden, CO, IV-D-2
Wilson, Natural Resources Advisory Committee, Cedar Grove,
N.J., IV-D-4
Roberts, Concerned citizen, Denver, CO, IV-D-5
Mannchen, Concerned citizen, Houston, TX, IV-D-6
Martin, Sierra Club, Houston, TX, IV-D-7
Marth, Concerned citizen, Costa Mesa, CA, IV-D-8
Hillestad, Concerned citizen, Denver, CO, IV-D-11
Hartzler, Concerned citizen, Goshen, IN, IV-D-12
Ellman, Concerned citizen, Tiburon, CA, IV-D-13
Gross, Concerned citizen, Wichita, KS, IV-D-14
Barcus, Concerned citizen, Wichita, KS, IV-D-15
Glover, Concerned citizen, Houston, TX, IV-D-18
James F. Presso, Concerned citizen, IV-D-23
(current standard or lower level)
Gluckman, Florida Lung Assoc., IV-F-11, p.67
Rains, Manasota 88; Manasota Chapter, Issac Walton League,
and the Environmental Confederation of Southwest Florida,
IV-F-11, p.78
Martin, Houston Sierra Club, IV-F-17, p.21; IV-F-19
Bass and Titus, League of Women Voters of Dallas, IV-F-17,
p.70; IV-F-23
•
Dixon, California Lung Assoc., IV-F-31, p.55
Goldsmith, Sierra Club, IV-F-31, p.61; IV-F-37
C. Freeman Allen, Concerned citizen, IV-F-40
Coombs, Maine Health Systems Agency, IV-D-24; IV-D-25
Fryan, Florida Lung Assoc., Northeast Branch, IV-D-27
Sagady, Michigan Lung Assoc., IV-D-28
2-1
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Chalupnik, Washington Air Quality Coalition, IV-D-39
Serra, Michigan Lung Assoc., Saginaw Valley Retion,
IV-D-45
Dtyzel, New Mexico Lung Assoc., IV-D-49
Platt and Renstrom, Oregon Environmental Council,
IV-D-50
American Lung Assoc. of New Jersey, IV-D-52
Vogel, South Shore (Ohio) Christmas Seal Assoc.,
IV-D-53
Curfman, Southwestern Ohio Lung Assoc, IV-D-55
Woodhull, Connecticut State Dept. of Health, IV-D-57.
(Allows very slight margin of safety.)
Lui, American Lung Assoc. of Colorado, IV-D-58.
Mehlhaff, Oregon Lung Assoc., IV-D-59.
(Objects of proposed relaxation of current standard
to 0.10 ppm.)
Monteith, Concerned citizen, IV-D-61
Knudson, American Lung Assoc. of Colorado, West Region,
IV-D-62
Ahlers, Queensboro Lung Assoc., Jamaica, N.Y., IV-D-64
McNulty, League of Women Voters of the U.S., IV-D-71
Raymond, American Lung Assoc. of Louisiana, IV-D-73
Lund, Concerned citizen, IV-D-79
Lee, Bangor-Brewer TB & Health Assoc., IV-0-80
Jensen, Medford-Ashland Air Quality Maintenance Advisory
Committee, IV-D-82
Mayer, Concerned citizen, IV-D-85
Ragadale, American Lung Assoc. of New York State, Inc.,
IV-D-89
Meierotto, U.S. Dept. of the Interior, IV-D-97
Malchon, National Air Convervation Commission, American
Lung Assoc., IV-D-102
Burk, Maine Lung Assoc., IV-D-107
Kuhn, Concerned citizen, IV-D-113
Randle, Yale Environmental Law Assoc., New Haven, CT.,
IV-D-14 (health hazards associated with the new standard
as proposed would be substantial)
Davis, New York Lung Assoc., IV-D-121
2-2
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2. Endorse proposed standard level, 0.10 ppm
Regional Planning Commission for Jefferson, Orleans,
St. Bernard and St. Tammany Parrishes, Louisiana,
IV-D-29
James Pitts, Concerned citizen, IV-F-31, p.27; IV-F-33
England, COLAB (Coalition of Labor and Business), IV-F-31,
p.66; IV-F-38
Rokaw, Air Quality Advisory Committee, California Dept. of
Health (endorsement of 0.10 ppm PO ), IV-F-31, p.70; IV-F-39
(S.M. Rokaw, M.D., who testified d§es not personally
endorse, but does not oppose 0.10 ppm PO , IV-F-31, p.79)
A
Auberle, Colorado Dept. of Health, IV-D-22
Morgan and Lash, U.S. Dept. of Transportation, IV-D-31
Foege, Center for Disease Control, USDHEW, IV-D-38
Moss, Wasatch Front Regional Council, Utah, IV-D-40
Jones and Johnson, Southern Alameda County (CA) Board of
Realtors, IV-D-51
MacCorison, Rhode Island Lung Assoc., IV-D-81
Cortese, Div. of Air and Hazards Materials, Massachusetts
Dept. of Envir. Quality Engineering, IV-D-99
Warner, Wayne County Dept. of Health, MI, IV-D-111
Howison, Air Pollution Control League of Greater
Cincinnati, OH, IV-D-119
Austin, California Air Resources Board, IV-D-120
3. Endorse level higher than 0.10 ppm
0.12 ppm:
Osegueda, Virginia APC Board, IV-F-1, p.131-132
Mattson, Virginia APC Board, IV-D-16
Schnetzke, Evansville, IN, Chamber of Commerce, IV-F-1,
p.137-138 (0.12 or 0.13 ppm)
Hovey, STAPPA, IV-F-1, p.114
Hodges, Tennessee Dept. of Public Health, IV-D-20
Williams, Indiana State Board of Health, IV-D-32
Ledbetter, Georgia Dept. of Natural Resources, IV-D-33
Rickers, Utah Bureau of Air Quality, IV-D-34
Jones, Sierra Pacific Power Co., IV-D-35
Noren, Maryland Environmental Health Administration,
IV-D-42
2-3
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Serdoz, Nevada Dept. of Conservation and Natural Resources,
IV-D-48
Lokey, Texas Oil Marketers Assoc., IV-D-54
Reilly, City of Philadelphia, PA, IV-0-63
Smither, Div. of Air Pollution Control, Kentucky Dept.
for Natural Resources and Environ. Protection, IV-D-68
Hambright, Bureau of Air Quality Control, Pennsylvania
Dept. of Environ. Resources, IV-D-69
Saiger, Bureau of Air Quality and Occup. HHh., Kansas
Dept. of HHh. and Environ., IV-D-77
Robinson, Air Pollution Control Div., Nebraska Dept.
of Environ. Control, IV-D-78
Rector, Air Quality Division, Michigan Dept. of Natural
Resources, IV-D-86
Robinson, Vulcan Materials Company, IV-D-87
Berle, N.Y. Dept. of Environ. Conservation, IV-D-92
Terrell, Area Cooperation Committee of Tidewater &
Virginia Peninsula Chambers of Commerce, IV-D-96
{averaging time 2, 4, or more hours.)
McRorie, N.C. Dept. of Natural Resources and Community
Development, IV-D-100
Hovey, STAPPA, IV-D-101
Leak, S.C. State Development Board, IV-D-108
Cooper, Alabama Air Pollution Control Commission, IV-D-112
Griffith, Berkeley, Charleston, Dorchester Council of
Governments, S.C., IV-D-115 (if clinical studies
documenting effects at 0.15 ppm are proved to be valid.)
0.13 ppm:
Harrison, San Antonio (TX) Metropolitan Health District,
IV-F-17, p.93; IV-F-26
J.R. Strausser, Concerned citizen, IV-D-37
0.14 ppm:
Rhoades, St. Louis County, MO, IV-D-110
0.15 ppm:
Huess, General Motors, IV-F-1, p.95
Coerver, Louisiana Air Control Commission IV-D-106
2-4
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0.20 ppm;
Stewart, Texas Air Control Board, IV-F-17, p.28; IV-F-20
(Basis: epidemiologic studies; apparently rejects experi-
mental studies because of singlet oxygen possibility.)
Hurstell, New Orleans Public Service, Inc., IV-0-90
(0.20 ppm 3-hour average, 1 exceedance/year.)
0.20 - 0.25 ppm:
Cyphers, Texas Chemical Council, IV-F-17, p.44; IV-F-21
0.20 - 0.30 ppm:
Conder, Dow Chemical Co., IV-D-109
0.23 - 0.35 ppm:
John H. Engle, Jr., Motor Vehicle Manufacturers Assoc.,
IV-F-31 , p.18 (response to question)
0.25 ppm:
L.B. McDonald, Concerned citizen, IV-D-41 (0.25 ppm, 2-hour
average, 10 exceedances/year)
Miller, Rio Blanco Oil Shale Co., IV-D-93
4. Oppose proposed standard, no specific level given
Walker, Monsanto Company, IV-F-17, p.Ill; IV-F-28
(Proposed changes are of such minor practical conse-
quences that they will serve only to delay more
appropriate changes.)
Mattson, Va. Air Pollution Control Board, IV-D-70
Foster, Div. of Air Pollu. Control, State of Tennessee
Dept. of Public Health, IV-D-104 (Standard should be
set at 80 percent of effects level. This amends
statments recommending standard should be set at
80 percent of 0.15 ppm, i.e. 0.12 ppm, made in
IV-F-11 and IV-F-13.)
Griffith, Berkeley, Charleston, Dorchester Council of
Governments, S.C., IV-D-115 (should not set standard
at this time because of lack of scientific concensus
on harmful concentration of ozone.)
Too lenient:
Mannchen, Concerned citizen, Houston, TX, IV-D-6
Kramer, Georgia Clean Air Council, IV-F-11, p.85;
IV-F-16
2-5
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Paul Miller, Concerned citizen, IV-F-31, p.34; IV-F-34
M. Mehlhaff, Oregon Lung Assoc., IV-D-59
(Change from 0.08 would be going downward instead of
upward.)
Bennett, Dept. Vegetable Crops, Univ. of California,
IV-D-72
Rogers, Natural Resources Council of Maine, IV-D-122
(should impose standard stricter than 0.08 ppm.)
Too Stringent:
Pierrard, API, IV-F-1, p.42
Hawk, API, IV-F-1, p.83
Huess, General Motors, IV-F-1, p.86,98
Osegueda and Mattson, Va ARC Board, IV-F-1, p.131-132;
IV-D-16 (24-hour averaging time is suggested.)
Gall ion, Oklahoma State Dept. Health, IV-D-10
Starke, Shell Oil Co., IV-F-11, p.16; IV-F-12
Packnett, Steams-Roger, Inc., IV-F-17, p.74; IV-F-24
(implied)
Feldcamp, Houston (TX) Chamber of Commerce, IV-F-17,
p.104; IV-F-27
McKenzie, Association of Local Air Pollution Control
Officials, IV-F-17, p.132
Greater San Antonio (TX) Chamber of Commerce, IV-F-30
Engel, Motor Vehicle Manufacturers Assoc., IV-F-31, p.15;
IV-F-32 (Prepared testimony)
Spaulding, Western Oil and Gas Assoc., IV-F-31, p.42;
IV-F-35
Edwards, Tennessee Eastman Corp., IV-D-26
Mole, Cook County (IL) Dept. of Environmental Control,
IV-D-30
Melchior, Associated Building Industry of Northern
California, IV-D-56
Hatladay, Utah Manufacturers Assoc., Salt Lake City,
UT, IV-D-66
Smith, Iowa-Illinois Gas & Electric Co., IV-D-105
Clark, Manufacturing Chemists Assoc., IV-D-116
Madsen, White River Shale Project, UT, IV-D-117
Potter, General Motors Corp., IV-D-118
2-6
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B. Secondary standard
1. Endorse proposed (current) standard level, 0.08 ppm
McNulty, League of Women Voters of the U.S., IV-D-71
Austin, California Air Resources Board, IV-0-120
2. Alternate proposals and criticism of proposed level
Paul R. Miller, Concerned citizen, IV-F-31, p.37
(0.05 ppm for 8 hours should be considered.)
0.10 ppm:
Williams, Indiana State Board of Health, IV-D-32
Jones, Sierra Pacific Power Co., IV-D-35
Warner, Wayne County Dept. of Health, MI, IV-D-111
0.12 ppm:
Rickers, Utah Bureau of Air Quality, IV-D-34
(Recommend same as primary standard: 0.12 ppm.)
Smither, Div. of Air Pollution Control, Kentucky Dept.
for Natural Resources and Environ. Protection, IV-D-68
Griffith, Berkeley, Charleston, Dorchester Council of
Governments, S.C., IV-D-115
Proposed level too stringent (no level stated):
Huess, General Motors, IV-F-1, p.98 (Protection of
vegetation requires secondary standard no more
stringent than primary standard.)
Hovey, STAPPA, IV-F-1, p.120
Collum, Georgia Dept. of Natural Resources, IV-F-11, p.61;
IV-F-15 (Implied too stringent)
Ledbetter, Georgia Dept. of Natural Resources, IV-D-33
(consider 8-hour averaging time)
Greater San Antonio (TX) Chamber of Commerce, IV-F-30
Hambright, Bureau of Air Quality Control, Pennsylvania
Dept. of Environ. Resources, IV-D-69
Rector, Air Quality Division, Michigan Dept. of Natural
Resources, IV-D-86
Berle, N.Y. Dept. of Environ. Conservation, IV-D-92
(Suggests either regional secondary standard or permit
each State to sec its own.)
Hovey, STAPPA, IV-D-101 (Suggests new nationwide dose
related secondary standard or separate standard for
each AQCR.)
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Foster, Div. of Air Pollution Control, State of
Tennessee Dept. of Public Health, IV-D-104
Potter, General Motors, Corp., IV-D-118
Howison, Air Pollution League of Greater Cincinnati,
OH, IV-D-119
Eliminate secondary standard:
Bargren, Illinois Manufacturer's Assoc., IV-D-43
II. Health Effects Criteria and Selection of Primary Standard
A. Completeness of data and general validity of conclusions
1. Science Advisory Board suggested changes in EPA interpre-
tation of various studies; EPA has failed to correct many
of the most significant defects. Hawk, IV-F-1, p.25.
2. Concern that EPA Science Advisory Board has recommended
that certain studies not be included in the Criteria
documents lest they receive unwarranted emphasis; studies
should be a valid part of the record unless refuted.
Rauch, EOF, IV-F-2, p.2.
3. EPA has not adequately justified a primary standard level
of 0.10 ppm. Faulkner, Arkansas Dept. of Pollution Control
and Ecology, IV-F-17, p.13; IV-F-18, and Stewart, Texas
Air Control Board, IV-F-17, p.23; IV-F-20.
4. Evaluations of the validity and inconsistency of the
evidence has not been given sufficiently objective
appraisal by EPA. E.W. Starke, Shell Oil Co., IV-F-11, p.10;
IV-F-12.
5. The Criteria documents lack the kind of convincing evidence
we'd like to have. McKenzie, Assn. of Local APC officials,
IV-F-17, p.129.
6. An ozone standard based solely on peak exposures and annual
concentration extremes fails to account for total ozone
dosage. Stewart, Texas Air Control Board, IV-F-17, p.25;
IV-F-20.
7. A large part of the data on which the standard is based used
measurements of total oxidants made with the inadequate
potassium iodide method. McKee, Houston Health Dept., IV-F-17,
p.54; IV-F-22
2-8
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8. An oxidant or ozone standard should require the presence of
threshold levels of one or more co-existing substances or
conditions. These could include concurrent concentrations
of: NO , N02-N0 ratio, NMHC, NO -NMHC ratio, aldehydes, and
various meteorologic parameters. Drone, Univ. of Florida,
IV-D-29.
9. There is no sound evidence as to health effects to humans
from oxidants at levels below 0.25 ppm/hr. EPA should
consider all evidence and information and should base
the standard on sound technical data. Melchior, Associated
Building Industry (Calif.), IV-D-56.
10. Properly conducted studies subject to peer review
support a Threshold no less than 0.30 ppm. Reilly, E.I.
Du Pont De Nemours & Co., IV-D-91.
11. The proposed standard is unsuitable because it is based
on faulty interpretation of pivotal data, because EPA
has never defined what constitutes "protection of public
health", and because the risk assessment technique on
which it is based in flawed. Miller, Rio Blanco Oil
Shale Co., IV-D-93.
Singlet Oxygen Possibility -
12. It has just been discovered in Texas Air Control Board
studies that ozone generators of the corona discharge and
U.V. types yield ozone and another oxidant, designated
"singlet oxygen", simultaneously; the amount of singlet
oxygen produced has been found to be as much as 3 times
the amount of ozone produced. This may make worthless
effects studies using such generators. Stewart, Texas
Air Control Board, IV-F-17, p.26-27; IV-D-20.
13. There is no direct evidence that singlet oxygen is bio-
logically reactive in the human respiratory tract, and
finding it in the generated air stream does not warrant
invalidation of conclusions drawn from experimental
biological research on ozone. (The theoretical half-life
of singlet oxygen.in dark space, such as that in the lung,
is only 9.0 X 10" minutes, that for ozone is 5000 times
greater.) Shy, Inst. for Environ. Studies, Univ. of N.C.,
IV-D-75.
14. Further experiments by the Texas Air Control Board indicate
that the additional oxidant is not singlet oxygen; the specific
identity remains an open question. Stewart, Texas Air Control
Board, IV-D-88.
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B. Definition of "Adverse Health Effect"
1. The term "adverse" (relative to health effects) has not
been adequately defined, but should be used in terms of
those that we recognize as being the most susceptible.
Mullenix, API, IV-F-1.
2. It has not been determined whether changes in pulmonary
function, changes in mean tidal volume or respiratory
rate, indicate adverse health effects; scientists are
beginning to question whether a change in biochemical
enzymes is an indication of adverse health effect. (On
inquiry to Hackney and DuBois neither could say
definitely that change in respiratory rate or mean tidal
volume would lead to a long-term disease or cause any
problem other than a temporary physiological change.)
Millenix, API, IV-F-1, p.58-59. (Note: Mullenix implies that
temporary or reversible changes are not adverse effects.
IV-F-1, p.60-61.)
3. Answers to question of what constitutes an adverse effect
in the continuum of responses which the body makes to
pollutant exposures are critical to the issue at hand.
Huess, General Motors, IV-F-1, p.91.
4. Quickly reversible irritation experienced for a short-
period of time falls in the category of comfort and well-
being and is contemplated to be taken into account in a
secondary standard. Van Voorhees, API, IV-F-1, p.70.
5. EPA has failed to adequately define what constitutes an
adverse health effect and at what point a measurable
response is a normal physiological fluctuation within
homeostasis. Engel, Motor Vehicle Manufacturers Assoc.,
IV-F-31, p.9; IV-F-32.
6. In response to a question regarding DeLucia and Adams'
results and identification of adverse effect: "...whether
chest tightness is really a health effect or is simply
a change, I really don't know " Engel, Motor Vehicle
Mfgr. Assoc., IV-F-31, p.17.
7. In response to a panel question: "As an M.D. do you believe
that difficulty in breathing or tightness of the chest as a
symptom of exposure to ozone constitutes an adverse health
effect?" Answer: "Yes". Rokaw, Air Quality Advisory
Committee, California Dept. of Health, IV-F-31, p.72.
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C. Comments on key studies
DeLucia and Adams
1. EPA significantly misreads the DeLucia and Adams study
as reporting significant effects at 0.15 ppm. Mullem'x,
API, IV-F-1, p.36.
2. The DeLucia and Adams study showed no statistically
significant changes is respiratory pattern (0.15 ppm
implied). Mullenix, API, IV-F-1, p.66.
3. In DeLucia and Adams studies no data on symptoms are given;
raw data should be given to permit judgement of its signi-
ficance. Huess, General Motors, IV-F-1, p.90.
4. Regarding the DeLucia and Adams studies, it is not clear
that inhalation of ozone via mouthpiece during stressful
exercise has application to ambient air standard; inhalation
by mouthpiece itself might have effects. Schnetzke, Evans-
ville, IND., Chamber of Commerce, IV-F-1, p.140.
5. DeLucia and Adams saw no significant effects from ozone
exposure below 0.30 ppm in heavily exercising subjects.
Starke, Shell Oil, IV-F-11, p.12.
6. Effects shown by DeLucia and Adams probably include the
effects of singlet oxygen. Stewart, Texas Air Control
Board, IV-F-11, p.27.
7. Powers quotes Mullenix, items II.C.I and II.C.2 above.
Powers, EXXON, IV-F-17, p.80.
8. Results of DeLucia and Adams do not support EPA interpre-
tation. With or without DeLucia and Adams, real health
effects due to ozone do not occur in man below 0.25 ppm.
Walker, Monsanto, IV-F-17, p.112.
9. EPA misreads DeLucia and Adams as showing effects at 0.15 ppm
ozone. It is asserted that DeLucia and Adams published
response data for .15 ppm ozone, along with reponse data
supplied by Adams for two additional subjects, fail to demon-
strate significance. Engel, Motor Vehicle Mfgr. Assoc.,
IV-F-31, p.11-14.
10. DeLucia and Adams demonstrated effects at 0.15 ppm ozone
on six healthy young non-smokers. The necessary inference
is that more susceptible populations (asthma and emphysema
victims, the elderly, and the young) would have shown similar
symptoms at lower level exposures. Dixon, California Lung
Assoc., IV-F-31, p.56.
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11. EPA reaches conclusions from DeLucia and Adams not
supported by the data. Reilly, E.I. Du Pont De Nemours
& Co., IV-D-91.
12. EPA has misinterpreted the meaning of the DeLucia and
Adams study. Clark, Mfgr. Chemists Assoc., IV-D-116.
Schoettlin and Landau
13. Even with reinterpretation of Schoettlin and Landau studies,
there remain problems with reliance on the studies because
of: (1) ambiguities in the studies, and (2) failure to
consider more recent well conducted studies on asthmatics
(Kurata, Hackney). Mullenix, API, IV-F-1, p.33-34.
14. Reinterpretation of Schoettlin and Landau results attributes
an increase in asthmatic attacks to a level of 0.25 ppm ozone.
Schnetzke, IV-F-1, p.138.
15. Same observation as II.C.14 above. Collum, Georgia Environ.
Protection Division, IV-F-11, p.58.
16. Upward reassignment of effects levels have been made for the
Schoettlin and Landau study; there still remains confusion
on how to interpret this study. Engel, Motor Vehicle Mfgr.
Assoc., IV-F-31, p.10.
17. EPA's new interpretation of Schoettlin and Landau is
unnecessarily conservative. Randle, Yale Environ. Law
Assoc., IV-D-114.
Hammer, et al
18. An unreliable diary technique was used and there is question
whether something other than oxidants caused symptoms in
the Hammer student nurse study. Mullenix, API, IV-F-1., p.37.
19. EPA assertions regarding the Hammer study, among others,
should be reexamined. Starke, Shell Oil, IV-F-11, p.12.
20. Hammer's study has a number of problems; 38 percent of sub-
jects were smokers and 25 percent had history of allergy.
No adjustments were made for these. Engel, Motor Vehicle
Mfgr. Assoc., IV-F-31, p.11.
Studies showing no effect at levels higher than
the propsed standard
21. None of the evidence would justify a standard based on a
finding of adverse health effects below the range of
0.25-0.30 ppm (ozone) for 2 hours. EPA seriously misinter-
prets the work of DeLucia and Adams. Hawk, API, IV-F-1, p.23.
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22. EPA identifies three kinds of effects demonstrated in humans
at low levels (of ozone exposure): aggravation of asthma,
reduction in pulmonary function, and chest discomfort and
irritation of the respiratory tract. None of these effects
has been demonstrated in even susceptable humans at 0.25 ppm
ozone for 2 to 4 hours. Mullenix, IV-F-1, p.32.
23. Hackney exposed asthmatics to 0.20 ppm ozone for 2 hours
under conditions of heat and exercise and found no significant
effect from ozone. Mullenix, API, IV-F-1, p.34.
24. Linn, et al, have shown no adverse effects on asthmatics
exposed to 0.20 ppm ozone for 2 hours during exercise.
Mullenix, API, IV-F-1, p.38.
25. Results by Hazucha (doctoral thesis) on impariment of
pulmonary function at ozone exposures of 0.25 ppm for
2 hours are not statistically significant; OeLucia and
Adams did not report any statistically significant
effects from ozone exposures below 0.30 ppm. Mullenix,
API, IV-F-1, p.36-37.
26. The National Academy of Science concluded in 1977 that
the effects on humans have been observed only from ozone
exposures above 0.25 ppm. Mullenix, API, IV-F-1, p.38.
(Note: Dr. J.H.B. Gardner, EPA, pointed out that the
National Academy of Science recommended to the Congress
that the 0.08 ppm standard be maintained. IV-F-1, p.54.)
27. Human health effects have been observed only from ozone
exposures well in excess of 0.25 ppm for 2 hours. Starke,
Shell Oil, IV-F-11, p.10.
28. The Von Nieding study, Hazucha and Bates, and various
Japanese studies should be reexamined by EPA before
promulgating a final standard. Starke, Shell Oil,
IV-F-11, p.12.
29. Hackney, Bates and Hazucha, Kerr, Folinsbee, and others
have observed human effects only after exposures above
0.25 ppm ozone for 2 or more hours, Starke, Shell Oil,
IV-F-11, p.12.
30. Health effects are observed above 0.15 ppm 0. in the
range of 0.37 ppm for 2 hours; no significant adverse
health effects have been observed at lower concentrations
or dosages. E.W. Starke, Shell Oil Co., IV-F-11, p.15;
IV-F-12.
31. The National Academy of Science has concluded that exposure
to 0.25 ppm ozone for 2 to 4 hours is a level at which
no adverse effects are observed. Cyphers, Texas Chemical
Council, IV-F-17, p.41. (In response to a question,
Cyphers stated that this is not an explicit conclusion of
NAS. IV-F-17, p.45.)
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32. EPA is unable to show that real health effects due to ozone
occur in man below 0.25 ppm; this is consistent with the
consensus of most of the informed medical community even
for susceptible humans. Walker, Monsanto, IV-F-17, p.112;
IV-F-28. (In response to questions, Walker identified
4 physicians whom he thinks hold this view. IV-F-17.
p.121-122.)
33. There appears to be no sound evidence of health effects of
oxidants on humans at levels below 0.25 ppm. Trimpey, Bay
Area League of Industrial Assocs., Inc., IV-D-47.
Other human studies
34. EPA cannot justify a conclusion that Japanese epidemio-
logical studies indicate a risk of symptomatic effects in
humans from ozone exposures below 0.15 ppm for 1 hour,
methodology deficiencies undermine their reliability.
Mullenix, API, IV-F-1, p.40.
35. The Science Advisory Board subcommittee urged EPA to re-
evaluate the interpretations of findings of Goldsmith's
and Von Nieding's studies. Starke, Shell Oil, IV-F-11, p.20.
36. Von Nieding has demonstrated effects on pulumonary function
of healthy individuals at 0.10 ppm ozone. Randle, Yale
Environ. LawAssoc., IV-D-114.
D. Use of animal studies
1. Reference is made to Criteria statements that ozone appears
to much more severly affect very young animals than the
adults of the species, and that recent reports from Japan
reveal that very young human children experience upper
airway difficulty at 0.04 ppm ozone. Rauch, EOF, IV-F-1,
p.12.
2. EPA has not produced an adequate rebuttal to its observation
of two years ago that 0.08 ppm ozone can reduce the capability
of body defense of animals to fight off infectious bacteria.
Rauch, EOF, IV-F-1, p.13.
3. There is no agreement among experts that humans experience
the effects which have been attributed to some animals.
Mullenix, API, IV-F-1, p.39.
4. The animal infectivity model gives no reason to believe that
an effect in humans would occur as low as 0.10 ppm ozone.
Huess, General Motors, IV-F-1, p.94.
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5. Health experts do not agree on extrapolation of the animal
infectivity experience to man. There is no evidence of
infection effect in epidemiologic studies in places like
Los Angeles. Huess, General Motors, IV-F-1, p.100-101.
6. Animal studies show effects at low levels; there are
difficulties in translating adverse effects in animals
to adverse effects in humans. Starke, Shell Oil, IV-F-11,
p.20.
7. Research done with young animals addresses a basic problem.
Animal studies are critical because they look at mechanisms
whereby humans might be affected but cannot be tested; one
will not subject a three-week old infant to experimental
exposures to oxidants. Gluckman, Florida Lung Assoc.,
IV-F-11, p.69.
8. Findings in five successfully replicated studies show
that test animals suffer increased susceptibility to
respiratory disease and mortality after 3-hour exposures
to ozone at 0.08 to 0.10 ppm. Dixon, Calif. Lung Assoc.,
IV-F-31, p.57.
9. Susceptibility of experimental animals to respiratory
infection increases after exposure to 0.10 to 0.15 ppm
ozone. Since the biochemistry in man is similar to such
animals in most respects it is reasonable to expect that
humans may be affected at these concentrations. Allen,
Concerned citizen (Pomona College), IV-F-40.
E. Exposure to sensitive groups
(See also II-C-11, 12, 13, 19, 20, 21, 29)
1. Sensitive people should be protected, but the degree
and nature of that protection requires thought and
discussion.... Staying indoors for a few hours a year
may be sufficient to protect the most sensitive people.
Huess, General Motors, IV-F-1, p.91-92.
2. Testing methods are deficient because one does not test
sick humans to learn how much sicker they become when
subjected to increased levels of oxidants. Gluckman,
Florida Lung Assoc., IV-F-11, p.73.
3. The public should be warned that the concept of thresholds
may be inappropriate in the case of ozone; yet tables in
FR26966-7 are based on threshold estimates for a precisely
defined segment of the most sensitive population. EPA
should not be obligatea at this time to express a standard
which addresses the most sensitive population; EPA states
that there is insufficient data to get such a standard.
Faulkner, Arkansas Dept. Pollution Control and Ecology,
IV-F-17, p.11-12.
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4. Exposure to ozone in the range 0.15-0.25 ppm may impair
mechanical function of the lung and may induce respiratory
and related symptoms in sensitive groups; this has important
public health implications, particularly for the developing
lungs of young children. (Quoting EPA Health Advisory
Panel), Martin, Houston Sierra Club, IV-F-17, p.19.
5. A person who is sensitive to ozone should be given credit
for an ability to recognize when he's affected by ozone
and go indoors. The concept of protecting the most
vulnerable subjects is open-ended because the sensitivity
begins at zero and works upward. Walker, Monsanto,
IV-F-17, p.126.
6. Although laboratory investigations with humans have apparently
not demonstrated significant effects at levels below about
0.25 ppm, they were done with ozone, not smog, and on healthly
subjects, not those with respiratory problems. Pitts,
Concerned citizen, IV-F-1, p.23.
7. The reactions of healthy young adults at 0.15 ppm ozone
implies effects at lower levels for more susceptible
people. Oixon, Calif. Lung Assoc., IV-F-31, p.57.
8. If 0.10-0.15 ppm ozone causes observable effects in
normal exercising human subjects, then it is reasonable
to expect that lower levels may cause similar effects
in exercising sensitive elements of the population.
Allen, Concerned citizen, IV-F-40.
9. Exposure to oxidants can bring on asthma attacks in sensitive
people. Current standards are based on effects on adults;
relaxation of the standard would pose an even greater threat
to children, whose tolerance is lower and susceptibility
higher to such pollutants. Lui, American Lung Assoc. of
Colorado, IV-D-58.
10. Concern is expressed for exposures of young children,
especially concern for protection of children with asthma.
Mehlhaff, Oregon Lung Assoc., IV-D-59.
F. Additive and synergistic effects, mixed exposures, and 0 vs 0.,
A J
1. Total exposure to the mixture of photochemical oxidants
should be the target, including peak concentrations of
synergistic materials. Faulkner, Arkansas Dept. of
Pollution Control and Ecology, IV-F-17, p.10.
2. We must have more information about human health effects
of ozone and more research on the synergistic reactions
of ozone with other atmospheric agents. Martin, Houston
Sierra Club, IV-F-17, p.21.
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3. Measured ozone levels raise serious questions about possible
health effects of other oxidant constituents such as
aldehydes, peroxyacetylnitrate, peroxides, and others. McKee,
Houston Health Dept., IV-F-17, -.57.
4. A report in Environment, June 1978, indicates that some
insecticides produced toxic effects 30 times greater with dust
and ozone than without. Bass, Dallas League of Women Voters,
IV-F-17, p.71.
5. Ozone does not occur alone in urban atmospheres; it must
be considered in relation to other contaiminants. Harrison,
City of San Antonio, IV-F-17, p.93.
6. The health impacts of photochemical air pollution arise not
only from ozone, but also from the spectrum of other gas and
particulate pollutants which coexist with it. Pitts, Concerned
citizen, IV-F-31, p.23.
7. Additive health effects are real; nitrous oxides have much the
same effects as ozone. Goldsmith, Sierra Club, IV-F-31, p.63.
8. The effects of ozone may be more severe in the presence of
other pollutants. Though not extensively studied, this has
been demonstrated and there is no reason to believe that the
worst case situation has yet been identified. Allen, Concerned
citizen, IV-F-40.
9. The presence of other oxidants and the possibility of
additive or synergistic effects of ozone and other pollutants
argue against changing the standard. Chalupnik, Washington
Air Quality Coalition, IV-D-39.
10. Synergistically the effects of chemicals can be far more
damaging to health (than the agents alone, -implied). Lui,
American Lung Assoc. of Colorado, IV-D-58.
11. Relaxing the standard now when there is new evidence for
effects from combinations of ozone and other common pollutants
appears irresponsible. Mehlhaff, Orgeon Lung Assoc., IV-D-59.
G. Margin of safety
Inadequacies:
1. Quote, Chairman, Panel for Photochemical Oxidants, WHO, "It is
apparent that any primary protection standard between 0.05 and
0.10 ppm will provide the narrowest margin of safety against
some possible detrimental effects in the more susceptible
segments of the population." Rauch, EOF, IV-F-1, p.11. (Rauch:
Don't believe they have adopted the standard. IV-F-1, p.17.)
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2. Criticizes means by which EPA reached the proposed level of
0.1 ppm ozone; quotes Federal Register preamble p.26967, col.l,
2nd complete paragraph:
"These figures illustrate several important
points: (1) all alternative standard levels reflect
some risk, (2) there is not sharp break in the
probability estimates that would suggest selecting one
alternative standard level over another, and (3) the
choice of a standard between zero and a level at which
health effects are virtually certain (0.15 ppm) is
necessarily subjective."
The next paragraph states in part:
"Based on all these data, it has been determined
that a standard of 0.08 ppm does not appear necessary
to protect public health. However, at this time it
appears that a standard above 0.10 ppm would not
adequately protect public health."
EPA has not justified it decision in terms of the statutory
requirement for an adequate margin of safety, and the
conclusion is legally inadequate. Rauch, EDE, IV-F-1,
p.10-11.
3. EPA must develop a legal rationale for a margin of safety.
Rauch, EOF, IV-F-1, p.18. This is necessary in situations
wherein no threshold p_er_ se_ can be identified. Rauch, EOF,
IV-F-2, p.3.
4. With health effects occurring around 0.15 ppm ozone, a
standard of 0.10 ppm gives an excessively low safety
factor. No information is offered on how the effects of
the proposed increase in ozone level will synergistically
interact with other air pollutants. Mannchen, Concerned
citizen, IV-F-6.
5. Quotes NAS 1974 review of standards for Senate Committee on
Public Works to the effect that a 20 percent margin of
safety is unreasonably low when experimental error in
controlled experiments is a least 35 percent and is probably
much greater in uncontrolled epidemiologic studies. Dixon,
Calif. Lung Assoc., IV-F-31, p.59.
6. Health effects data, public responses, and new laboratory
experimental work indicate that for 0.1 ppm level the margin
of safety against health effects is quite scanty. Rokaw.
Air Quality Advisory Committee, Calif. Oept. of Health,
IV-F-31, p.71.
7. The present 0.08 ppm standard allows a very slight margin
of safety. Woodhull, Conn. Oept. of Health, IV-D-57.
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Adequate:
8. There are questions regarding the DeLucia and Adams studies,
but proceeding on the basis that they are valid, the ENCON
and STAPPA proposed standard of 0.12 ppm ozone will still
have an adequate 25 percent margin of safety. Hovey, STAPPA,
IV-F-1, p.116.
9. If there is confidence that effects below a particular level
are unlikely even in sensitive groups, then an adequate margin
of safety has been identified and the standard may be set at
that level. Hawk, API, IV-F-1, p.28.
10. Somewhere in the range 0.25 to 0.30 ppm is the level at which
no significant health effects occur. Adding to that a margin
of safety, 0.02 ppm was used in the 1971 standard, suggests
an appropriate standard. Hawk, API, IV-F-1, p.54.
11. Regarding a panel question on margin of safety: Two things
at least should be considered, (1) attainability of the
standard, and (2) the magnitude of risk associated with any
particular level. Starke, Shell Oil Co., IV-F-11, p.18.
12. Consistency with past decisions would have the new standard
set at 80 percent of the health effect level. Foster, Tenn.
Dept. Public Health. IV-F-11, p.30.
13. The standard should be 0.12 ppm for 1 hour; this maintains
the 25 percent margin of safety of the original standard.
Collum, Georgia Envir. Protection Division, IV-F-11, p.59.
H. The margin of safety previously used would result in a new
standard of 0.2 ppm ozone An additional margin of
safety is provided by the fact that indoor levels of ozone
have been shown to be less than half the outdoor levels.
Cyphers, Texas Chemical Council, IV-F-17, p.42.
15. Indoor ozone levels are lower than corresponding outdoor
levels; for sensitive people, usually indoors, an additional
margin of safety is provided. Feldcamp, Houston Chamber of
Commerce, IV-F-17, p.104.
16. We should establish a standard at 0.02 ppm below a health
effects threshold level. Engel, Motor Vehicle Mfgr. Assoc.,
IV-F-31, p.17.
17. A 0.12 ppm standard with a 0.15 ppm effects level has the
same 20 percent margin of safety as was adopted for the
current standard. Ledbetter, Ga. Dept. of Natural Resources,
IV-D-33.
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Excessive:
18. With no effects identified below 0.30 ppm (ozone) EPA has
offered inadequate explanation for the excessive margins
of safety inherent in the present standard and the proposed
primary standard. Huess, API, IV-F-1, p.22.
19. EPA concludes that the margin of safety should be 2 1/2
times greater than that set in 1971. This is based on
several studies which supply scanty support. Mullenix,
API, IV-F-1, p.39.
20. The proposed standard has an unjustifiably large margin of
safety. Starke, Shell Oil Co., IV-F-11, p.15.
21. In opting for such a large safety factor (0.1 ppm standard
vs 0.25 ppm effects level) EPA overlooked a major safety
factor in the enormous difference between (outdoor) monitoring
values and actual (indoor) exposures. Walker, Monsanto,
IV-F-17., p.113.
22. Considering Schoettlin and Landau, DeLucia and Adams, and
the Japanese studies, it is concluded that a NAAQS of 0.12 ppm,
or possibly 0.14 ppm ozone would provide an adequate margin
of safety. Robinson, Vulcan Materials Co., IV-D-87.
23. EPA has used an excessive margin of safety in the current
proposal. Clark, Manufacturing Chemists Assoc., IV-D-116.
24. Reconsider whether 0.05 ppm margin of safety is essential.
Potter, General Motors, Corp., IV-D-118.
Cost Considerations:
25. EPA should consider cost/effectiveness in evaluations to
determine the margin of safety for the standards. Huess,
General Motors, IV-F-6.
26. The tremendous impact on the economy by restrictive
standards should persuade EPA to weigh carefully whether
a safety margin as large as 0.05 ppm is essential. Huess,
General Motors, IV-F-1, p.98.
27. Since the proposed standard is substantially below the
level of adverse health effects, the attainability and
economic impact of the standard become important consider-
ations in determining the margin of safety. Stone, Western
Oil and Gas Assoc., IV-F-31, p.49.
28. Cost is a consideration in factor of safety for any level
above zero. Reilly, E.I. De Pont De flemours & Co., IV-D-91.
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General considerations:
29. In setting a standard the margin of safety is critical
(concern for effect on children). Ellison, Council woman,
Ventura, CA., IV-F-31, p.31.
H. Procedural issues
1. EPA has chosen to rely on an irregular Advisory Panel
instead of on recommendations of the statutory Science
Advisory Board. Hawk, API, IV-F-1.
2. EPA has developed the standard through an irregular
process based on conclusions rejected or severly ques-
tioned by the legitimate expert scientific review body.
Hawk, API, IV-F-1, p.26.
3. API questions whether the appropriate or even the required
use was made of the Scientific Advisory Board which has
legal status under the Clean Air Act and is concerned with
procedural aspects relative to the Advisory Panel on Health
Effects. Hawk, API, IV-F-1, p.50-51.
4. API contends that certain legal requirements on establishment
and use of Advisory Committees were not followed in the case
of the Advisory Panel on Health Effects. Van Voorhees,
API, IV-F-1, P.51.
5. The Advisory Panel on Health Effects met privately and a
complete record of its deliberations has not been made
available to the public. Powers, EXXON, IV-F-17, p.82.
6. EPA did not seek Science Advisory Board Review of the proposed
standard and failed to accord proper weight to SAB recommen-
dations for changes in the revised criteria document. EPA
did not place primary reliance for the choice of standard
on the revised criteria, but used staff papers, an irregular
Advisory Panel, and an unreviewed experimental risk assess-
ment technique. Spaulding, Western Oil and Gas Assoc.,
IV-F-31, p.44.
7. EPA does not incorporate the provisions of the Clean Air
Act which deal with significant deterioration into the
revision of the standard. Faulkner, Ark. Dept. of Pollution
Control and Ecology, IV-F-17, p.12.
8. The advisory panel on health effects contravenes the Federal
Advisory Committee Act of 1972, and was not "fairly balanced".
Reilly, E.I. Du Pont De Nemours & Co., IV-D-91.
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III. Welfare Effects Criteria and Selection of the Secondary Standard
A. Completeness and reliability of data and conclusions
1. In considering effects on vegetation there is a failure to
distinguish between the effects of ozone and those of other
photochemical oxidants. There is apparent reliance on the
results of vegetation studies using extremely sensitive
strains which overstate the aggregate effects caused by
ozone in the ambient air. Hawk, API, IV-F-1, p.30.
2. Experiments on vegetation are flawed because in their
design the large natural ozone burden was not taken into
account; clean filtered air was used for control rather
than natural ozone. Huess, General Motors, IV-F-1, p.97.
3. It has not been adequately demonstrated that secondary
standard of 0.08 ppm is necessary to protect welfare.
Smither, Div. of Air Pollution Control, Kentucky Dept. for
Natural Resources & Environ. Protection, IV-D-68.
B. Effects levels and damage functions
1. There is no evidence that a secondary standard more stringent
than the primary standard is necessary to protect vegetation -
generally thought to be the main basis for the secondary
standard. Huess, General Motors, IV-F-1, p.86.
2. Except for limited sensitive species most plants are not
harmed at levels well above the secondary standard; review of
the proposed level and averaging time is advocated. Suggest
consideration of a growing-season standard is a secondary
standard is justified. Hovey, STAPPA, IV-F-1, p.120.
3. Setting a standard for ozone alone fails to consider other
phytotoxic pollutants; synergistic interactions, principally
of ozone and sulfur dioxide, can cause injury at lower concen-
trations than can the pollutants separately. Miller, U.S.
Forest Service, IV-F-31, p.34.
C. Cost and benefits
1. An adequate economic analysis will reveal that the pro-
posed secondary standard is far too stringent to protect
the public welfare. (To be expanded in written comment.)
Hawk, API, IV-F-1, p.29.
2. Economic assessment for welfare effects is based on overly
optimistic assumptions of ozone air quality improvements
resulting from RACT; the RACT cost estimate is substantially
low; inflationary impact is ignored. Pierrard, API, IV-F-1,
p.46-47.
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3. The analysis done on the secondary standard doesn't allow
increment analyses to show total cost in achieving various
levels of a standard; costs and benefits cannot be portrayed.
Everett, API, IV-F-1, p.79.
4. There are alternative strains of vegetation, more resistant
to ozone damage, which should be considered in the trade-offs
of cost-benefit analyses. Everett, API, IV-F-1, p.82.
5. Costs of controlling from 0.10 to 0.08 ppm ozone is estimated
by EPA to range from $1 billion to $3 billion, but the economic
benefit is unknown; it must be less than the $300 million which
EPA estimates to be the vegetation damage from ozone. Huess,
General Motors, IV-F-1, p.97.
6. It is obvious that an impact (by pollution) on cultivated
crops would adversely affect food productivity and the national
economy; erosion of air quality standards in incompatible with
the long-term maintenance of these national assets. Miller,
U.S. Forest Service, IV-F-31, p.36.
7. The Clean Air Act requires consideration of economic factors
in setting the secondary standard; EPA has failed to do so.
The required cost-benefit analyses have not been done. Stone,
Western Oil and Gas Assoc., IV-F-31, p.50.
8. The cost figure of significance is the differential cost
of control necessary to achieve the secondary standard
over and above the cost to achieve the primary standard.
Hambright, Bureau of Air Quality Control, Pennsylvania
Dept. of Environ. Resources, IV-D-69.
9. The level of the secondary standard is improper because
it does not account sufficiently for economic values and
improper criteria for plant damage were adopted. Miller,
Rio Blanco Oil Shale Co., IV-D-93.
IV. Risk Assessment
1. EPA's risk assessment technique remains incomplete, its use in
standard setting is premature and inappropriate. (Defects will
be detailed in API's written comments.) Hawk, API, IV-F-1, p.27.
2. The risk assessment method used extensively by EPA in arriving
at the proposed 0.10 ppm standard has not had complete review
by the Science Advisory Board or others. If it is to be so
used, the method should be published with opportunity for
comment before the new standard is promulgated. Stewart,
Texas Air Control Board, IV-F-17, p.24.
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3. EPA has not had adequate review of the risk assessment method-
ology. Powers, EXXON, IV-F-17, p.81.
4. The risk assessment results are unclear. The states would
like to review the EPA assessment approach. Hovey, STAPPA,
IV-F-1, p.117.
5. There is need to assess risk to human health. Starting with
the lowest level for which there is significant adverse effect
on health one would assess risks at that level and below that
level. Starke, Shell Oil Co., IV-F-11, p.18.
6. We need to reassess the total system and the methods by which
EPA establishes standards. We are giving economic consideration
too much weight. Gluckman, Fla. Lung Assoc., IV-F-11, p.73.
7. The risk assessment technique should not be used because
it has not been reviewed adequately by the Science Advisory
Board or the scientific community. Miller, Rio Blanco
Oil Shale Co., IV-D-93.
V. Form of the NAAQS
A. Ozone standard vs oxidant standard
1. Ozone standard is preferred to oxidant standard
Huess, API, IV-F-1, p.85.
Hovey, STAPPA, IV-F-1, p.117.
Schnetzke, Evansvilie, Ind., Chamber of Commerce,
IV-F-1, p.136.
Starke, Shell Oil Co., IV-F-11, p.8.
Foster, Tenn. Dept. Public Health, IV-F-11, p.38.
Coll urn, Ga. Environmental Protection Division,
IV-F-11, p.57.
Martin, Houston Sierra Club, IV-F-17, p.18
(Standards are needed for other photochemical
oxidants as well.)
Stewart, Texas Air Quality Control Board, IV-F-17, p.70.
Bass, Dallas League of Women Voters, IV-F-17, p.70.
Powers, EXXON, IV-F-17, p.79.
Walker, Monsanto, IV-F-17, p.111.
Stone, Western Oil and Gas Assoc., IV-F-31, p.47.
Sierra Club, IV-F-37.
Beadle, U.S. Dept. of Energy, IV-D-21.
Auberle, Colorado Dept. of Health, IV-D-22.
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Morgan and Lash, U.S. Dept. of Transportation, IV-0-31.
Noren, Envr. Health Admin., Maryland Dept. of Health
and Mental Hygiene, IV-D-42.
McNulty, League of Women Voters of the U.S., IV-D-71 .
Bennett, Dept. Vegetable Crops, Univ. of Calif., IV-D-72 .
Robinson, Vulcan Materials Co., IV-D-87 .
Hurstell, New Orleans Public Service Inc., IV-D-90.
Berle, N.Y. Dept. of Environ. Conservation, IV-D-92.
Scott, Arizona Dept. of Health Services, IV-D-98.
Cortese, Div. of Air and Hazardous Materials, MA, IV-D-99.
Hovey, STAPPA, IV-D-101.
Peterson, Eastman Kodak Co., IV-D-103.
Smith, Iowa-Illinois Gas & Electric Co., IV-D-105.
Coerver, Louisiana Air Control Commission, IV-D-106.
Griffith, Berkeley, Charleston, Dorchester Council of
Governments, S.C., IV-D-115.
Clark, Manufacturing Chemists Assoc., IV-D-116.
Howison, Air Pollu. Control League of Greater Cincinnati,
OH, IV-D-119.
Oxidant standard is preferred to ozone standard
Roberts, Concerned citizen, Denver, CO., IV-D-5.
Henke, Water and Wastewater Systems, Streamwood, IL.,
IV-D-9 (03 is water additive.)
Pitts, Concerned citizen, IV-F-31, p.23.
Rokaw, Air Qua!. Advisory Comm., Calif. Dept. of
Health, IV-F-31, p.70.
Sagady, Mich. Lung Assoc., IV-D-28.
Serdoz, Nevada Dept. of Conservation and Natural
Resources, IV-0-48.
Okey, Envirotech Research Center, Utah, IV-D-65,
(03 is water and wastewater additive.)
Kominek, Envirotech, EIMCO Process Machinery Div.,
Utah, IV-D-67. (03 is water additive.)
Austin, Calif. Air Resources Board, IV-D-120.
3. General
Redesignation as an ozone standard (vs oxidant) does not
remove the confusion of these agents in the criteria
document. McKee, Houston Health Dept., IV-F-17, p.53.
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Although the new standard addresses ozone only, the
discussion relates to the entire photochemical system;
other constituents are not properly addressed. McKenzie,
Assoc. of Local ARC Officials, IV-F-17, p.130.
B. Separate PAN standard
1. Agree with EPA that a separate PAN standard should not be
promulgated at this time:
Starke, Shell Oil Co., IV-F-11, p.8.
McKee, Houston Health Dept., IV-F-17, p.58.
There is insufficient knowledge at this time, but the
problem may be as serious as that of ozone.
Auberle, Colorado Dept. of Health, IV-D-22.
PAN should be a pollutant of concern and specific
studies undertaken.
Bennett, Dept. Vegetable Crops, Univ. of Calif., IV-D-72
(PAN standard should be developed as soon as possible.)
Cortese, Div. of Air & Hazardous Materials, MA, IV-D-99.
C. Statistical form vs deterministic form
1. Statistical form is preferred over deterministic form
Schnetzke, Evansville, Ind. Chamber of Commerce, IV-F-1,
p.141.
Powers, EXXON, IV-F-17, p.79.
(Need detailed technical analysis supporting specific
choice of form.)
McKenzie, Assoc. of Local APC officials, IV-F-17, p.132.
("We ask that a still more improved statistical base
be utilized in determining the exceedance kind of
discussion.")
Stone, Western Oil and Gas Assoc., IV-F-31, p.46.
(Form adopted still has problems.)
Beadle, U.S. Dept. of Energy, IV-D-21.
Auberle, Colorado Dept. of Health, IV-D-22.
(Grave reservation concerning some aspects of
statistical form proposed.)
Morgan and Lash, U.S. Dept. of Transportation, IV-D-31.
Serdoz, Nevada Dept. of Conservation and Natural Resources,
IV-D-48.
Bennett, Dept. Vegetable Crops, Univ. of Calif., IV-D-72.
Miller, Rio Blanco Oil Shale Co., IV-D-93.
(Some reservations regarding proposed form.)
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Cortese, Div. of Air & Hazardous Materials, MA, IV-D-99.
Peterson, Eastman Kodak, IV-D-103.
Smith, Iowa-Illinois Gas & Electric Co., IV-D-105.
Coerver, Louisiana Air Control Commission, IV-D-106.
Austin, Calif. Air Resources Board, IV-0-120.
2. Oppose statistical form
Hovey, STAPPA, IV-F-1, p.118.
(Prefers deterministic to the proposed statistical
form, IV-F-1, p.127-129.)
Collum, Georgia Envr. Protection Div., IV-F-11, p.61.
(Prefers deterministic, IV-F-11, p.64.)
Faulkner, Ark. Dept. Pollution Control and Ecology,
IV-F-17, p.10,11,15.
McNulty, League of Women Voters of U.S., IV-D-71.
Rector, Air Quality Div., MI, IV-D-86.
Scott, Arizona Dept. of Health Services, IV-D-98.
3. General comments
Deterministic form is inappropriate, but it is doubtful
that the proposed statistical form is an improvement.
Starke, Shell Oil Co., IV-F-11, p.9.
Both current (deterministic) and proposed (statistical)
forms, based on peak exposures, fail to account for total
ozone dosage. Stewart, Texas Air Control Board, IV-F-17,
p. 25, 30-32.
Weibull distributions have a tendency to predict highest
or second highest annual values greater than actually
occur. Ollison, Amer. Petroleum Institute, IV-D-76.
A more sophisticated procedure is needed in handling of
missing data. Hovey, STAPPA, IV-D-101.
D. Allowable exceedances
1. Opposes relaxing exceedances from 1 hourly average to 1
day with hourly averages over the standard. Mannchen,
Concerned citizen, Houston, TX, IV-F-6.
2. Supports 1-hour averaging time for both primary and
secondary standards. Bennett, Oept. Vegetable Crops,
Univ. of Calif., IV-D-72.
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3. Assess compliance on basis of number of days with one or
more hourly exceedances: (Problem: multiple exceedances
in successive hours.)
Pierrard, API, IV-F-1, p.42-43.
Hovey, STAPPA, IV-F-1, p.118,126.
Cyphers, Texas Chemical Council, IV-F-17, p.45.
McKenzie, Assoc. of Local APC Officials, IV-F-17,
p.134.
Stone, Western Oil and Gas Assoc., IV-F-31, p.47.
Morgan and Lash, U.S. Dept. of Transportation,
IV-D-31.
Saiger, Bureau of Air Quality and Occup. Hlth,
Kansas Dept. of Hlth. & Environ., IV-D-77.
Rector, Air Quality Div., Michigan Dept. of Natural
Resources, IV-D-86.
Berle, N.Y. Dept. of Environ. Conservation, IV-D-92.
Miller, Rio Blanco Oil Shale Co., IV-D-93.
Beuforado, Minnesota Minning & Manufacturing Co.,
IV-D-94.
Hovey, STAPPA, IV-D-101.
Clark, Manufacturing Chemists Assoc., IV-D-116.
Other limits of exceedance
4. Recommends averaging time interval of 24 hours. Osegueda,
Virginia APC Board, IV-F-1, p.131. (Because of reference
to STAPPA this is assumed to mean hourly exceedances in
one day.)
5. Propose that there be allowed more consecutive hours at
lower readings before there is a designation of non-
attainment. Schnetzke, Evansville Chamber of Commerce,
IV-F-1, p.143.
6. Suggest that the standard disregard exceedances attributable
to natural causes; determinations of freon concentrations
and Be activity can be used to distinguish anthropogenic
genesis and incursions. Foster, Tenn. Dept. of Public
Health, IV-F-11, p.32.
7. Recommends consideration of several days or several conse-
cutive hours of exceedance in determining violations.
Collum, Georgia Envir. Protection Division, IV-F-11, p.64.
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8. Exceedances should discount events associated with unusual
meteorological conditions. Faulkner, Ark. Oept. of Pollution
Control and Ecology, IV-F-17, p.11.
9. Violation should be based on 3 or more days of exceedances.
Cyphers, Texas Chemical Council, IV-F-17, p.43.
10. The number of allowable exceedances should have sound
statistical basis; it should take into account unique
meteorologic events causing more than 1 high hour in a
single day or single high levels during non-ozone seasons.
Auberle, Colorado Dept. of Health, IV-D-22.
11. A minimum of 20 exceedances should be allowed to compensate
for God made ozone. Mole, Cook County Dept. of Envr. Control,
(IL), IV-D-30.
12. A one hour value one time per year is overkill. Daniel,
Va. ARC Board, IV-D-36.
13. A localized normal should be established for abnormal
meteorological events leading to exceedances. Moss, Wasatch
Front Regional Council (Utah), IV-D-40.
14. Provision must be made for setting aside events in aerometric
data record which are due to natural sources. Bailey, API,
IV-F-1, p.56.
15. A standard involving only one hour is untenable. Mattson,
Va. Air Pollution Control Board, IV-D-70.
16. Exceedances caused by metorological events and instrument
malfuction or unusual event should be discontinued. Koslow,
Yolo-Solano, Air Pollution Control District, IV-D-83.
17. Averaging time for exceedances should be 3 hours. Hurstell ,
New Orleans Public Service, Inc., IV-D-90.
18. Prefer assessment of compliance to be based on percent of
hourly exceedances per year. Cortese, Div. of Air &
Hazardous Materials, MA, IV-0-99.
19. Recommend statistical standard based on a percentile of
hours (preferably days) of exceedances. Coerver,
Louisiana Air Control Commission, IV-D-106.
20. Allowable frequency of exceedance should be changed to a
more robust statistic. Potter, General Motors Corp., IV-D-118.
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Secondary standard
21. There appears to be no justification for the secondary standard
of 0.08 ppm on a 1-hour average. Consider a growing season
standard if a secondary standard is justified. Hovey, STAPPA,
IV-F-1, p.120.
22. 8-hour secondary standard may be appropriate. Cortese,
Div. of Air & Hazardous Materials, MA, IV-0-99.
23. Favor 0.08 ppm 8-hour averaging time. Smith, Iowa-
Illinois Gas & Electric Co., IV-D-105.
VI. Implementation and Attainability
A. Natural background levels of ozone
1. Standard should consider high natural background levels of ozone
Hawk, API, IV-F-1, p.29.
Pierrard, API, IV-F-1, p.43,44,48.
Bailey, API, IV-F-1, p.56.
Huess General Motors, IV-F-1, p.86.
Hovey, STAPPA, IV-F-1, p.126.
Osegueda, Mattson, Virginia APC Board, IV-F-1, p.131.
Packnett, Steams-Roger, Denver, CO, IV-0-17.
Faulkner, Ark. Dept. of Pullution Control and Ecology, IV-F-11,
p.10.
Melchior, Associated Building Industry of Northern California,
IV-D-56.
Milbrodt, South Lake Tahoe, Calif., IV-D-60.
Smither, Div. of Air Pollu. Control, Kentucky, IV-D-68.
Koslow, Yolo-Salano, IV-D-83.
Berle, N.Y. Dept. of Environ. Conservation, IV-D-92.
Miller, Rio Blanco Oil Shale Co., IV-D-93.
Beuforado, Minnesota Mining & Manufacturing Co., IV-D-94.
Hovey, STAPPA, IV-D-101.
Griffith, Berkeley, Charleston, Dorchester Council of
Governments, S.C., IV-D-115.
Madsen, White River Shale Project, IV-D-117.
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2. Standards are unattainable because of natural background
Congress intended standards to be attainable; the proposed
secondary standard is rendered unattainable by natural back-
ground ozone. Hawk, API, IV-F-1, p.29.
Extreme measures in SIP's will not achieve attainment because
of the impact of natural ozone. Pierrard, API, IV-F-1, p.48.
Increasing evidence indicates that ozone from natural sources
precludes attainment of present standards in many, if not most,
areas. Starke, Shell Oil Co., IV-F-11, p.10.
0.08 ppm standard is exceeded by natural background ozone.
Foster, Tenn. Dept. of Public Health, IV-F-11, p.31; IV-D-104.
Natural ozone may exceed 0.08 to 0.12 ppm on a regular basis.
Davis, Ga. Inst. Tech., IV-F-11, p.40.
0.10 ppm ozone cannot be achieved in some pristine areas
because of natural background. Packnett, Steams-Roger,
IV-F-17, p.73. (e.g. at elevations over 5,000 to 6,000 ft.,
IV-F-17, p.76.)
Standard will be impossible to meet because of intrusions
of stratospheric ozone. Hodges, Tenn. Dept. of Public Health,
IV-D-20.
In remote parts of the country natural God made ozone frequently
exceeds the standard. Mole, Cook County Dept. of Environmental
Control, IV-D-30.
Natural Ozone will exceed 0.10 ppm. Potter, General Motors
Corp., IV-D-118.
B. Non-background attainment problems
1. Relaxation of the standard may change some urban areas from
non-attainment to attainment, permit greater hydrocarbon
emissions, and contribute to or aggravate violations downwind.
Rauch, EDF, IV-F-1, p.14.
2. EPA's failure to consider adequately the role of nitrogen
oxides in its control strategies is a serious deficiency.
The proposed revision of Part 51 to recognize the importance
of nitrogen oxides in ozone formation is commendable.
Pierrard, API, IV-F-1, p.45.
3. EKMA fails to account for temporal and spatial distributions
of sources in the design of control strategies. Because
control efforts will be extremely costly, control strategies
should use the most effective models. Pierrard, API
IV-F-1, p.46.
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4. Annual emission inventories may not be adaptable to modeling
for means to control 1-hour average levels. Hovey, STAPPA,
IV-F-1, p.119.
5. Present standards cannot be attained in most areas even if
widespread gasoline rationing and/or massive industrial
shutdowns were put into effect. Starke, Shell Oil Co.,
IV-F-11, p.10.
6. A rural non-attainment area faces economic sanctions when
an offset policy is imposed on a prospective industrial
establishment. Drye, Buncombe County, N.C., IV-F-11, p.27.
7. Both rollback techniques and EKMA approaches to control
strategies proposed by EPA have shortcomings. Stone,
Western Oil and Gas Assoc., IV-F-31, p.48.
8. Relaxation of the standard, along with EPA control strategy
policy, increases the difficulty of achieving the standard
by shifting more of the burden of control to the states
where ozone is measured and away from those where emissions
originate. Schneidermeyer, Conn. Dept. of Environmental
Protection, IV-D-46.
9. Resort areas at high elevations face special attainment
problems because of (1) elevation, (2) high natural hydro-
carbons (terpenes), (3) many visiting motor vehicles are
adjusted for operation at lower elevations. Milbrodt,
South Lake Tahoe, Nev., IV-D-60.
C. Congressional intent on attainability of standards
1. Congress contemplated that primary standards should be
attainable. Van Voorhes, API, IV-F-1, p.78.
(Note: Lee, EPA, observed that standards (secondary?) need
not be immediately attainable or attainable by current
technology, IV-F-1, p.79.)
2. While the legislative history of the Clean Air Act indicates
that EPA may set standards beyond the reach of current techno-
logy, we cannot believe that Congress would expect control
below the natural background. Huess, General Motors, IV-F-1,
p.89.
3. Congress intended standards to be set at the highest possible
level consistent with protection of public health; it wished
to minimize the social and economic disruptions attendant
on attaining and maintaining air qualitv. Starke, Shell Oil
Co., IV-F-11, p.15.
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4. Standards are to be based on criteria relating to the level
needed to protect public health and welfare; cost of achieving
the standards or existence of control technology are not germane
to the determination. Martin, Houston Sierra Club, IV-F-17,
p.20.
D. Control of hydrocarbons and its correlation with ozone levels
1. Relaxation of control requirement may permit greater
amounts of hydrocarbon carcinogens as well as oxidant
precursors to be emitted. Rauch, EOF, IV-F-1, p.14.
2. Hydrocarbon control may or may not be effective in reducing
maximum ozone concentrations. Pierrard, API, IV-F-1, p.45.
3. Time requirements for implementation of control of hydro-
carbon emissions from painting processes is difficult; much
more could be done by 1987 than by 1982. Huess, General
Motors, IV-F-1, p.99-100.
4. Use of free radical scavenger atmospheric additives (e.g.
diethylhydroxylamine) is an effective means for controlling
ambient concentrations of photochemical oxidants. Reaction
products of DEHA are not deleterious and DEHA does not reach
the stratosphere. Heicklen, Penn. State Univ., IV-F-1,
P.105,109,112.
5. Poor correlation exists between control of hydrocarbons and
ozone level. Packnett, Steams-Roger, Denver, CO, IV-D-17.
6. Despite reactive compound emission reductions of 40 percent
in the Houston Region and 46 percent in the Southeat Texas
Region, reductions in ozone concentrations are not demon-
strated. Foster, Tenn. Dept. of Public Health, IV-F-11,
p.32.
7. It is not known whether reduction of hydrocarbon emissions
while allowing nitrogen oxide emissions to increase makes
urban air more or less healthful. Stewart, Texas Air Control
Board, IV-F-17, p.26.
8. Hydrocarbon control appears to have been ineffective in
reducing ozone episodes in Houston. Perhaps ozone forma-
tion is limited by oxides of nitrogen rather than by hydro-
carbons. McKee, Houston Health Dept., IV-F-17, p.52-56.
9. Recent studies in the Houston area have shown negative
correlation between ozone and ncnmethane hydrocarbon
concentrations. Packnett, Sterns-Roger, IV-F-17, p.74.
10. In areas (e.g. rural) where NMHC to NO ratios are greater
than 30:1, ozone formation if insensitive to initial
hydrocarbon concentration, so hydrocarbon control is
inappropriate for ozone control. Miller, Rio Blanco Oil
Shale Co., IV-D-93.
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Data collection and monitoring methodology
1. Agree with change in calibration technique
Pierrard, API, IV-F-1, p.42.
Hovey, STAPPA, IV-F-1, p.119.
Starke, Shell Oil Co., IV-F-11, p.9.
McKee, Houston Health Dept., IV-F-17, p.56.
(recommends holding in abeyance prospective change to
boric acid method.)
Powers, EXXON, IV-F-17, p.79.
Stone, Western Oil and Gas Assoc., IV-F-37, p.46.
Hodges, Tenn. Dept. of Health, IV-D-20.
Moss, Wasatch Front Regional Council, Utah, IV-D-40.
Smither, Div. of Air Pollution Control, Kentucky
Dept. for Natural Resources & Envir. Protection,
IV-D-68.
Bennett, Dept. Vegetable Crops, Univ. of Calif., IV-D-72.
Rector, Air Quality Div., Michigan Dept. of Natural
Resources, IV-D-86.
Berle, N.Y. Dept. of Environ. Conservation, IV-D-92.
Scott, Arizona Dept. of Health Services, IV-D-98.
Hovey, STAPPA, IV-D-101.
Warner, Wayne County Dept. of Health, MI, IV-D-111.
Austin, Calif. Air Resources Board, IV-D-120.
2. Agree with chemiluminescence monitoring method.
Starke, Shell Oil Co., IV-F-11, p.9.
3. EPA should expand its monitoring system for measuring
background levels of natural ozone. Huess, General
Motors, IV-F-1, p.86.
4. The proposed formula penalizes those northern states
which may sample on a seasonal basis. Hovey, STAPPA,
IV-F-1, p.118.
5. Development of a weighted formula expressed in terms of
contact/concentration hours for determining compliance is
suggested. Schnetzke, Evansville, Ind., Chamber of Commerce,
IV-F-1, p.141.
6. Criticizes EPA for setting a standard then proposing a new
monitoring method. Foster, Tenn. Dept. of Public Health,
IV-F-11, p.33.
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7. Concerned that data analysis procedures (accounting for
missing data) will promote redundant monitoring at expense
of monitoring in dirty areas. Faulkner, Ark. Dept. of
Pollution and Ecology, IV-F-17, p. 11.
8. We should not rely on ozone monitoring for assurance that
photochemical oxidant problems are being solved. Martin,
Houston Sierra Club, IV-F-17, p.18.
9. An adequate monitoring network must consider vertical as
well as horizontal distributions (mountain elevations).
Miller, U.S. Forest Service, IV-F-37, p.34.
10. None of the four modeling techniques acceptable to EPA are
applicable to predicting ozone concentrations in rural
areas. Miller, Rio Blanco Oil Shale Co., IV-D-93.
Effect of standard promulgation on SIP submissions
1. Revision of standard may adversely affect timely submission
of SIP revisions.
Hawk, API, IV-F-1, p.30.
Hovey, STAPPA, IV-F-1, p.118.
Starke, Shell Oil Co., IV-F-11, p.16.
(Recommends 9-month extension from promulgation date.)
Bass, Dallas League of Women Voters, IV-F-17, p.70.
Harrison, City of San Antonio, IV-F-17, p.94.
Spaulding, Western Oil and Gas Assoc., IV-F-37, p.43.
Mattson, Va. Air Pollu. Control Board, IV-D-70.
Miller, Rio Blanco Oil Shale Co., IV-D-93.
Terrell, Area Cooperation Committee of Tidewater &
Virginia Peninsula Chambers of Commerce, IV-D-96.
G. Cost
1. Peak hourly natural ozone concentrations between 0.08 ppm
and 0.10 ppm occur in remote locations in the order of
once a year. 0.08 ppm is unachievable and cost benefit
studies hsould be done on whether secondary standard more
stringent than primary standard is needed. Huess, General
Motors, IV-F-1, p.88,97.
2. Substantial cost savings can be made by control agencies
when seasonal monitoring can be practiced. Hovey, STAPPA,
IV-F-1, p.118.
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3. Controlling ozone to low levels will have significant impact
on economic and social activity, the standard should be no
more stringent than protection of the public health demands.
Hovey, STAPPA, IV-F-1, p.121.
VII. Other
A. Speakers stated intentions to supply written comments
Hawk, API, IV-F-1, p.26,27,30,49.
Pierrard, API, IV-F-1, p.41,44.
Huess, General Motors, IV-F-1, p.85,101; IV-F-6, p.6,19.
Hovey, STAPPA, IV-F-1, p.118,119,121,125,129.
Osegueda, IV-F-1, p.134. (Supplied as IV-D-36.)
Starke, Shell Oil Co., IV-F-11, p.26.
Feldcamp, Houston Chamber of Commerce, IV-F-17, p.106.
(Objective regarding Houston health effects study.)
Walker, Monsanto, CO, IV-F-17, p.125.
(Re: references on exposure levels vs monitored levels.)
Engel, Motor Vehicle Mfgrs. Assoc., IV-F-37, p.21.
(Guidance regarding definition of adverse health effect -
equivocal answer.)
Rokaw, Air Quality Advisory Committee, Calif. Dept. of Health,
IV-F-37, p.78.
B. Wish to put questions to EPA
Hawk, API, IV-F-1, p.49,84.
2-36
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3.0 OVERVIEW AND SUMMARY
A review of the public comments outlined in Section 2.0 reveals
that there is still disagreement on interpretation of health effects
information compiled in Criteria documents and on the selection of the
primary standard. Environmental groups and private citizens in general
advocate retaining the current 0.08 ppm one-hour standard. Some control
agencies, associations, and individuals endorsed the proposed 0.10 ppm
primary standard, but control agency spokesmen generally support
relaxation to 0.12 ppm hourly average to be exceeded on no more than one
day per year. Industry representatives advocated higher levels, in the
range 0.15 ppm to 0.25 ppm, or did not recommend specific levels, but
criticized the proposed level as being too stringent.
Adequacy and/or interpretation of specific studies cited for health
effects (DeLucia and Adams, Schottlein and Landau, Hammer et al, Japanese
epidemiologic studies) were criticized, primarily by industry spokesmen,
but in some control agency testimony as well, as not justifying the
proposed standard. Particularly noteworthy in regard to experimental
studies is a report by the Texas Air Control Board that common types of
ozone generators, as used in experimental studies, produce an oxidant,
identified in August 22 testimony as "singlet oxygen", which, although
generated in substantial concentration, is not measured by the ozone
analytic procedure; it is suggested that this may invalidate a number of
experimental studies. By letter of September 18, 1978, the Texas Air
Control Board advised that laboratory experiments done since August 22
indicate that the additional oxidant, though still present, is not
singlet oxygen.
3-1
-------
An issue was raised on the definition of "adverse health effect".
There was difference of opinion, unresolved in the hearings, on what is
merely an observable physiological response (e.g. compensation) and what
is an effect on health. Responses to exposures at 0.15 ppm reported by
DeLucia and Adams were generally characterized by critics as not being
significant health effects. A number of speakers maintained that
significant health effects in humans have not been demonstrated at
levels below 0.25 ppm ozone. Others disagree with this contention that
0.25 ppm (or other reported "no effect" level) is a valid index level
for no effect because any such reported level relates to responses of
generally healthy young adult experimental subjects, not to susceptible
segments of the population - particularly infants, young children, and
ill people - who are never used as experimental subjects. It was pointed
out that animal work showing differences between responses of adults and
the very young is especially important in this regard. Further, actual
ambient exposures are to mixtures of pollutants with their synergistic
activities, not to the single pollutant, ozone, as used in experimental
exposure systems.
Rauch of the Environmental Defense Fund maintains that methods
reported to have been used by EPA in deciding on the proposed primary
standard are legally vulnerable, particularly on the statutory margin of
safety issue. Some speakers felt that the margin of safety in the
proposed standard was marginal or inadequate; about the same number felt
that it was excessive. Several speakers consider a standard set 20 to
25 percent below the lowest reported effect level comprises an adequate
margin of safety. A few maintain that a margin of 0.02 ppm (an absolute
value from the 1971 standard) is appropriate.
3-2
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Use of the ad hoc Advisory Panel on the Health Effects of Photo-
chemical Oxidants by EPA in its development of the proposed standard was
criticized, primarily on procedural grounds, by industry spokesmen.
Rauch, EOF, criticized dismissing some studies which, in the judgement
of the Science Advisory Board, might receive unwarranted emphasis
(carcinogens, mutagenesis, chromosomal aberrations?), unless these
studies have been shown to be invalid.
Little was said of the proposed secondary standard except that some
speakers consider it to be unrealistically low, subject to violation by
natural background ozone, and/or that it is not necessary for it to be
lower than the primary standard. It was stated that only especially
sensitive vegetation species are damaged at ozone levels as low as
0.08 ppm.
The thrust of discussion on risk analysis, primarily by industry
spokesmen, was that use of the method in standard setting is premature.
Additional scientific scrutiny is needed.
Most agencies which addressed the matter favor an ozone standard
over an oxidant standard, although there was some support for an oxidant
standard. There was no testimony in favor of a PAN standard at this
time.
Although a number of persons supported a statistical form of the
standard, there was still substantial support for the deterministic
form, particularly by the STAPPA spokesman and some State air pollution
control agencies.
Several speakers and persons submitting written testimony observed
that two or more consecutive hours of exceedance may occur in a single
day and advocated that determinations of compliance or violation of the
3-3
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standard be based on the number of days on which one or more hourly
exceedances occur. Support for the current limit of one hour per year
exceedance is implied, but was not explicitly stated, by supporters of
the current standard.
Discussion of attainment problems included frequent mention of
ozone concentrations from natural sources approaching or exceeding the
proposed standards. Control programs, or mechanics of control received
little mention except for discussion of the lack of positive correlation
between non-methane hydrocarbon emission and ozone concentrations in the
Houston region.
There was general agreement with the proposed change in instrument
calibration technique.
There was some disagreement with the EPA position that revision of
the oxidant standard will not upset the time schedule for revisions of
SIP's due January 1, 1979.
3-4
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EPA amends Part 50 of Chapter I, Title 40, of the Code of Federal
Regulations as follows:
/") 1. Section 50.9 is revised as follows:
c. -
-r'" I 50.9 National primary and secondary ambient air qua-lity
,, standards for ozone,
J ,-ri
<^j<'' (a) The level of the national primary and secondary ambient air
1>-L quality standards for ozone measured by a reference method based
on Appendix D to this part and designated in accordance with Part
53 of this chapter-, or by an equivalent method designated in
accordance jw-ith' Part 53 of this chapter, is O.le part per million
(Wfr ug/m3). The standard is attained when the expected number of
days per calendar year with maximum hourly average concentrations
/*- ^
above O.JQ part per million 096 ug/nTJ is equal to or less than
one, as determined by Appendix H.
2. In Appendix D, as well as in the table of sections for Part 50,
the title is revised to read as follows: Appendix D -Measurement
Principle and Calibration Procedure for the Measurement of Ozone
in the Atmosphere.
3. Appendix H is added as follows:
APPENDIX H - INTERPRETATION OF THE NATIONAL AMBIENT AIR
QUALITY STANDARD FOR OZONE
1. General
This appendix explains how to determine when the expected number
of days per calendar year with maximum hourly concentrations above
0.10 ppm (196 ug/m3) is equal to or less than one. An expanded discussion
of these procedures and associated examples are contained in the "Guice-
line for Interpretation of Ozone Air Quality Standards." For purposes
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74
of clarity in the following discussion, it is convenient to use the
term "exceedance" to describe a daily maximum hourly ozone measurement
that is greater than the level of the standard. Therefore, the phrase
"expected number of days with maximum hourly ozone concentrations above
the level of the standard" may be simply stated as the "expected number
of exceedances".
The basic principle in making the above determination is
relatively straightforward. Most of the complications that arise
in determining the expected number of annual exceedances are
consequences of accounting for incomplete sampling. In general, the
average number of exceedances per calendar year must be less than or
equal to 1. In its simplest form, the number of exceedances at-a monitor'
site would be recorded for each calendar year and then averaged over the
past three calendar years to determine if this average is less than or
equal to 1.
2. Interpretation of Expected Exceedances
The ozone standard states that the expected number of exceedances
per year must be less than or equal to 1. The statistical term
"expected number" is basically an arithmetic average. The following
example explains what it would mean for an area to be in compliance
with this type of standard. Suppose a monitoring station records a
daily maximum ozone value for every day of the year during the past
three years. At the end of each year, the number of days with maximum
hourly concentrations above 0.10 ppm is determined and this is averaged
with the results of previous years. As long as this average remains
"less than or equal to 1" the area is in compliance.
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75
3. Estimating the Number of Exceedances for a Year
In general, a value may not be available for each hour of the
year and it will be necessary to account for these missing values
when estimating the number of exceedances for a. particular calendar
year. It should be noted that the purpose of these computations is
to determine if the expected number of exceedances per year is less
than or equal to 1. Thus, if a site has two or more observed
exceedances each year, the standard is not met and it is not necessary
to use .the procedures of this section to account for incomplete sampling.
The term "missing value" is used here in the general sense to de-
scribe all days that do not have an associated ozone measurement. In
some cases, a measurement might actually have been missed but in other
cases no measurement may have been scheduled for that day. A daily
maximum ozone value is defined to be the highest hourly ozone value
recorded for the day. This daily maximum value is considered to be
valid if 75 percent of the hours from 9:01 a.m. to 9:00 p.m. (1ST) were
measured or if the highest hour is greater than the level of the standard.
In some areas the seasonal pattern of ozone is so pronounced that
entire months need not be sampled because it is extremely unlikely that
the standard would be exceeded. Any such waiver of the ozone monitoring
requirement will be handled under provisions of the newly proposed 40 CFR
58. To avoid unfairly penalizing such areas, some allowance must be made to
allow for days that were not actually measured but would quite likely have
been below the standard. This introduces a complication in that it
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Ur
>"** {
.
0
_j/ Yvyw"%
P/o becomes necessary to define under what conditions a missing value
may be assumed to have been less than the level of the standard. The
following criterion may be used for ozone:
A missing daily ozone value may be assumed to be less than the
level of the standard if both the daily maximum preceding and the
daily maximum following this missing day do not exceed 75 percent of
the level of the standard.
Let z denote the number of missing daily values that may be
assumed to be less than'the standard. Then the following formula
shall be used to estimate the expected number of exceedances for the
e = v +[(v/n) * (N-n-z)] (1)
(indicates multiplication)
Where
e = the estimated number of exceedances for the year.
- ^
N = the number of required monitoring days in the year
n = the number of valid daily maxima
v = the number of daily values above the level of the standard
z = the number of days assumed to be less than the standard level
This estimated number of exceedances shall be rounded to
one decimal place (fractional parts equal to 0.05 round up).
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77
It should be noted that N will be the total number of days
in the year unless the appropriate Regional Administrator has granted
a waiver under the provisions of 40 CFR 58.
The above equation may be interpreted intuitively in the
following manner. The estimated number of exceedances is equal to
the observed number of exceedances (v) plus an increment that • accounts
for Incomplete sampling. There were (N-n) missing values for the
year but a certain number of these, namely z, were as'sumed to be less
than the standard. Therefore, (N-n-z) missing values are considered to
Include possible exceedances. The fraction of measured values that are
above the level of the standard is v/n. It is assumed that this same
fraction applies to the (N-n.-z) missing values and that (v/n)*(N-n-z)
of these values would also have exceeded the level of the standard.
4. Use of multiple years of data. - Ideally, the expected number
-of exceedances for a site would be computed by knowing the probability
that the site would record 0, 1, 2, 3 ... exceedances in a year. Then
each possible outcome could be weighted according to its likelihood of
occurrence and the appropriate expected value, or average, could be com-
puted. In practice, this type of situation will not exist because ambient
data will only be available for a limited number of years.
Consequently, the expected number of exceedances per year at a site
shall be computed by averaging the estimated number of exceedances for
each year of available data during the past three calendar years. In
other words, if the estimated number of exceedances has been computed
for the calendar years of 1974, 1975, and 1976 then the expected number
of exceedances is estimated by averaging those three numbers. If
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78
this average is greater than 1, then the standard has been exceeded at
this site. It suffices to carry one decimal place in this computation.
For example, the average of the three namoers 1, 1 and 2 is 1.3 which
is greater than 1. If data is not available for each of the- last three
years then this average shall be-computed on the basis of available
data from the remaining years in that period.
AUTHORITY': Sections 109 and 301 of the Clean Air Act, as amended
(42 U.S.C. 7409, 7601).
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TAB 0
SUMMARY STATEMENT FROM THE EPA ADVISORY PANEL
ON HEALTH EFFECTS OF PHOTOCHEMICAL OXIDANTS
January, 1978
Prepared for the Environmental Protection Agency
under the supervision of the Institute for Envirunmental
Studies of the University of North^Carolina.at Chapel Hill
re
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I. Composition of the Panel
The Advisory Panel on Health Effects of Photochemical Oxidants (here-
after called the "Health Panel") was convened at the request of the
Office of Air Quality Planning and Standards, U. S. Environmental
Protection Agency. The Institute for Environmental Studies, University
of North Carolina at Chapel Hill, served as advisor in the selection of
panel members and as host for the panel meeting held in Chapel Hill,
N. C. on June 7th and 8th, 1977. Panel members were:
Carl M. Shy, (Panel Chairman), Director, Institute for Environmental
Studies, University of North Carolina at Chapel Hill
Stephen M. Ayres, Chairman, Department of Internal Medicine, St.
Louis Univeristy School of Medicine
David V. Bates, Dean, Faculty of Medicine, University of British
Columbia
T. Timothy Crocker, Chairman, Department of Community and Environmental
Medicine, University of California College of Medicine, Irvine
Bernard D. God!stein, Associate Professor, Department of Medicine
and Department of Environmental Medicine, New York University School
of Medicine
John R. Goldsmith, Environmental Epidemiology Unit, California State
Department of Public Health
Staff and scientists of the U. S. Environmental Protection Agency participated
in the discussions of the Health Panel; documents prepared by EPA staff
were distributed and, where appropriate, commented on. The conclusions and
recommended guidelines for protection of public health given in this
summary statement represent a consensus of the panel members only.
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II. Purpose and Scope of the Meeting
The purpose of the panel discussions was to interpret the current
state of knowledge on health effects of ozone and other photochemical
substances, with the objective of developing a guideline to the Environ-
mental Protection Agency (EPA) for the protection of public health.
These discussions were prompted by EPA's current program for review
and re-assessment of the existing air quality standard for photochemical
oxidants.
The panel reviewed studies relating to the following categories of
health effects:
A. Human studies
1. Mechanical function of the lung (controlled human exposures)
2. Asthma and lung function in children
3. Athletic performance
4. Other effects: mortality, occupational hazards
B. Toxicological studies
1. Experimental infection of animals
2. Morphological abnormalities of the respiratory system
3. Biochemical effects
4. Mutagenic and teratogenic potential
5. Performance and behavioral effects
In its discussions, the Panel considered several issues bearing on the
overall interpretation of reported studies. Among the major issues were:
relative weights to be given to published and unpublished reports, concept
of threshold concentrations for effects, human health significance of
toxicological data, chemical specificity of the air quality standard
("ozone," "oxidants," "photo-chemical substances") margins of safety, and
the health significance of exceeding a stated concentration one or more
times.
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III. Format for Discussion of Health Effects
The EPA staff requested the Panel to consider three characteristics
of population exposure that bear upon protection of public health: the
concentration at which human health risk would be increased, the duration
of exposure which is related to this risk, and the temporal exposure
pattern that would be associated with increased risk. In its deliberations
on each category of health effects, the Panel addressed the probability
that the health effects are induced by exposure to ozone or other photo-
chemical substances, the severity of each health effect and the uncertainties
of the evidence.
IV. Concept of Threshold Concentrations
A threshold was defined as a concentration between a no-effect
level and the lowest concentration at which a health effect was demon-
strated. Identification of a threshold relevant to protection of public
health requires evidence for specific exposures that produce no effect
as well as exposures that produce effects in susceptible segments of the
population. The Panel emphasized that biological reactions to pollutants
are not characterized by sharp discontinuities in dose-response relationships,
and that demonstration of no-effect levels is dependent upon the sensi-
tivity of the measurement of effects and exposure, as well as the selection
of the most sensitive groups and reaction systems. Since "thresholds"
will depend upon who is studied and what is measured, it is unlikely that
scientific evidence for a specific effects threshold can be satisfactorily
derived from existing data. Limited studies can be performed on groups
of unusually sensitive persons. Most experimental studies of humans are
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performed on small numbers of healthy subjects who do not adequately
reflect the range of human sensitivity. lexicological studies
usually cannot utilize appropriate models of sensitive human popu-
lations. Thus, the Panel concurred in the statement that thresholds
for sensitive persons are difficult or impossible to determine experi-
mentally, while the threshold for healthy persons or animals is not
likely to be predictive of the response of more sensitive groups.
The Panel discussed alternatives to the "threshold" concept for
arriving at recommended guidelines for protection of public health. An
acceptable alternative considered by the Panel was
(1) to state at what level health effects have been demonstrated
in population groups, in controlled human exposures, and in
experimental animals,
(2) to evaluate the relationship between the responses of subjects
or animals studied and sensitive segments of the population,
(3) to assess the severity of each category of effect,
(4) to recognize the uncertainty in this body of evidence,
(5) to propose guidelines for a margin of safety, given the
strength of the evidence, the severity of the effects, and
the magnitude of the uncertainties,
(6) to recognize that decisions on margins of safety involve
more than scientific evidence.
V. Acceptabiliy of Cited Reports
In their assessment of evidence from the various sources of information
on health effects, Panel members agreed that greater weight should be
given to peer reviewed publications than to unpublished reports or reports
published without this review. The Panel felt that the latter category
of data should be considered, but could not serve as a major contribution
to its recommendations concerning public health protection. Overall,
-------
there was a sufficient body of peer reviewed publications to serve alone
as the basis for the Panel's recommendations. In the one instance where
a significant human effect was demonstrated at a low ozone exposure, the
Panel took account of the data but made its conclusion -primarily on the
basis of other published evidence.
VI. Human Studies
A. Mechanical function of the Lung
The Panel focused its discussion on the more recently published
human exposure data as reported by von Nieding, et al. (1977a, 1977b),
Hackney et al. (1975a, 1975b, 1975c, 1977), Bates and Hazucha (Bates
and Hazucha 1973, Hazucha 1973, Hazucha et al. 1973, Hazucha and Bates
1975). The Panel agreed that there was convincing evidence for pro-
nounced effects on mechanical function of the lung, as variously
measured by flow rates, airway resistance and other parameters of
ventilatory function, at ozone exposures of 0.37 to 0.75 ppm for two
hours under conditions of intermittent moderate exercise. The Panel
also accepted the validity of findings showing an effect on lung
function at 0.25 ppm, but recognized that these effects were less
pronounced than at higher concentrations and that they occurred in
Montreal subjects and not in Los Angeles subjects studied under iden-
tical protocols. The difference between the dose-response relationships
for Los Angeles and Montreal subjects was felt to be explainable by one
or more of the following factors: adaptation in Los Angeles subjects,
admixture of submicronic aerosols in the Montreal chamber, and/or
selective migration away from Los Angeles of persons who could not tolerate
previous repeated ambient ozone exposures without undue reactions.
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The Panel also identified the fact that a plateau in the dose-response
relationship in Montreal subjects was not demonstrated, and therefore that
effects may be produced at even lower concentrations than those employed.
In support of this hypothesis were the data from recent publications of
von Nieding et al. (1977a, 1977b). Differences from other study protocols
in the measurement of airway resistance and of arterial partial pressure of
oxygen were recognized. The small standard error about mean values of airway
resistance was also noted. The Panel felt that these aspects of the von
Nieding studies required replication of their results by other investigators
but that the data waSrtfhereby invalidated. The Panel concluded that
results of the von Nieding studies served to reinforce the conclusion that
changes in mechanical function of the lung may well occur in some subjects
at ozone concentrations less than 0.25 ppm for two hours, and that there may
be some risk of inducing functional changes at levels in the range of 0.15
to 0.25 ppm.
The Panel considered the issue of repetitive experimental exposures,
and asked whether effects on mechanical function would be more severe
with repetition of exposure or would possibly occur at lower concentrations
with repetition of exposure. The Panel consensus was that the risk of
effect was related to the total dose of ozone delivered to the respiratory
tract within a day (but not over long periods), and that this dose
increased with the frequency of exposures, with the concentrations of a
single exposure, and with the intensity of exercise of exposed subjects.
The Panel concluded that the evidence for a relationship between ozone
exposure and effects on mechanical properties was conclusive. In
discussing the severity of this effect, the Panel agreed that one exposure
-------
.ay not portend risk of serious consequences in healthy individuals. How-
ever, a single exposure of a sensitive individual such as an asthmatic,
or other persons with airway disease, may induce a serious health effect,
and repeated exposures even of healthy individuals may lead to increased
risk of respiratory impairment in the form of irreversible effects or
susceptibility to chronic respiratory disease. However, the Panel
recognized that judgments concerning repetition of exposures fall in
the area of greatest uncertainty because experimental human studies have
not been conducted to evaluate repetitions of exposure. The Panel
also cited recent experimental evidence that the maximum stimulus to
histamine release in the lung occurred 24 hours after ozone exposure,
suggesting that exposed persons with sensitive airways may experience
untold delayed effects. These findings are not fully understood and
generally have not been incorporated into the assessment of ozone
induced health effects.
B. Asthma and Lung Function in Children
The Panel reviewed the air quality data available for interpreting
the findings of the Schoettlin and Landau (1961) asthma study. Although
there was some confusion in the early reviews of this study, it is now
clear that oxidant measurements for each day were made by the Los
Angeles Air Pollution Control District, that these data were obtained
by the potassium iodide method, and that there were significantly more
asthma epidodes in subjects on days when peak oxidant concentrations
exceeded 0.25 ppm, and finally that these peak concentrations were
associated with average maximum hourly oxidant concentration of about
0.20 ppm. From these data, the Panel agreed that the evidence supported
the statement that a proportion of asthmatics will be affected by maximum
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8
hourly oxidant concentrations of 0.20 ppm, and that the effect is likely
to occur at concentrations in the range of 0.15 to 0.25 ppm in some
asthmatics or other persons with sensitive airways.
The Panel also considered the recent reports of Kagawa and Toyama
(1975) and Kagawa et al. (1976) on the association of changes in lung
function of school children with oxidant exposure. These published
reports show a decrease in ventilatory function of school children
associated with increasing ambient ozone concentrations, from 0.1 to
0.30 ppm. The Panel noted that the authors stratified the data into
low and high temperature seasons, but could not isolate the effect of
ozone from other measured pollutants, since population exposures only
occur in the presence of pollutant combinations, not for single pollutants
in isolation. The Panel concluded that these studies further supported the
evidence for an increased health risk from ozone exposures over the range
of 0.15 to 0.25 ppm, and for the likelihood of a lesser but real health
risk at even lower concentrations.
The Panel expressed additional concern for ozone exposures of
young children, in view of the findings of Bartlett et al. (1974) which
demonstrated a reduction in lung elasticity and overdistention of the
lungs of rats exposed at 3-4 weeks of age for 30 days to 0.2 ppm ozone.
The Panel felt that these data were particularly significant since there
is continuous growth of lung capacity, in humans, both in terms of
number of alveoli and ventilatory function from birth to age 8 or 9
years, and since ozone exposures which compromise lung development at
these ages might have serious implications for risk of impairment later
in life.
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The evidence that ozone effects may be enhanced by other concurrent
pollutants (Bates and Hazacha 1973) was interpreted by the Panel as
indicating the desirability of providing a margin of safety between
these observed effects and the primary standard for ozone and other
photochemical substances.
C. Respiratory and Other Symptoms in Human Populations
Experimental exposures of humans and epidemiological observations
support the conclusion that ozone exposures in the range of 0.15 to
0.25 ppm are associated with increased risk of cough, chest discomfort,
susternal soreness, headache and eye irritation. Respiratory symptoms
are enhanced by more intense exercise. The Panel judged that the attempts
to obtain threshold estimates for these effects (Hammer et al., 1974)
violated biological evidence for nonlinear dose-response relationships,
and that in general, segmental regression analysis ("Hockay-stick"
function) is inappropriate for determining the onset of health risk.
In reviewing the several Japanese reports on acute respiratory and
other symptoms in school children during "photochemical smog" episodes,
the Panel noted the occurrence of acute effects at ozone levels of 0.15
ppm and above. The Panel attributed the high rate of reporting of
symptoms in the Japanese episode to a combination of several factors.
(1) biological reactions producing manifest symptoms, particularly
in actively exercising school children,
(2) Probable combination of ozone with other pollutants which interact
in their biological effects,
(3) sociological factors which in one culture may result in repression
of perceived symptoms and in another articulation of perceived
symptoms, and
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10
(4) psychological factors which may alter the individual's judgment
concerning the severity of symptoms.
One or more of these factors may account for the apparently high
incidence of chest discomfort and eye irritation in affected
juvenile groups and for the associated extrapulmonary mani-
festations such as numbness, fainting and necessity for
hospitalization. Thus the Panel concluded that the Japanese
reports of symptoms at 0.15 ppm should be given due weight
in arriving at a guideline for public health protection.
The repetition of these episodes with associated symptoms
adds to their significance.
D. Athletic Performance
The Panel's previous comments concerning the inappropriateness of
segmental regression analysis was stated to apply to Wayne et al.'s (1967)
study of athletic performance. The data as presented in the original
study do not suggest a plateau in the dose-response function. Never-
theless, some members of the Panel were unconvinced of an association
between impaired performance and oxidant concentrations less than 0.15
ppm. However, these members stated that their judgment was based on a
visual truncation of data points rather than on quantitative statistical
analysis. The Panel noted that a recent paper (Folinsbee et al. 1977)
has documented a decline in maximal oxygen uptake in healthy young
subjects exercising under controlled experimental exposure to 0.75 ppm
ozone, thus suggesting a mechanism for the effect on athletic performance.
E. Other Effects: Mortality, Occupational Hazards
Review of existing studies fails to show any evidence for increased
risk of mortality in association with daily oxidant concentrations
measured in the Los Angeles basin. The Panel stated that there was no
new evidence to alter this conclusion.
The Panel expressed concern with the absence of studies of different
groups occupationally exposed to ozone. These groups include airline
pilots and crews, workers exposed to coronal discharges in the electric
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11
utility industry, and other persons working in the vicinity of ultraviolet
lights, e.g., in cold storage rooms. The Panel was quite convinced that
some adverse reactions would be produced in these occupational settings,
and expressed concern that the absence of systematic studies will lead to
continued exposures without identification of the induced health risks.
F. Conclusions from Human Studies
The Panel reached consensus on the conclusion that short term exposures
to ozone in the range of 0.15 ppm to 0.25 ppm may impair mechanical function
of the lung, and may induce respiratory and related symptoms in sensitive
segments of the population. These symptoms and effects will be more
readily induced in exercising subjects, particularly in a complex urban
atmospheric environment in which ozone can interact with other pollutants.
Short term exposures only 3 or 4 times this level, that is, exposures
to 0.75 ppm for two hours, can induce severe symptoms in exercising sub-
jects. Such experiments are ethically unacceptable.
The Panel judged that the occurrence of respiratory symptoms and
alteration of mechanical function of the lung have important public health
implications, particularly for the developing lungs of young children.
Although such effects appear to be reversible in exposed young adults, they
represent a potentially serious risk for asthmatics and other individuals
with airway disease. In the population of individuals with varying states
of biological adaptability, exposures which produce the above described
effects may at times overwhelm the biological defense of some persons. Thus
reversibility of effects in experimentally exposed healthy subjects should not
be generalized to the entire population.
The Panel related many of the experimental human effects to a two-hour
averaging time. However, the Panel noted that more intense exercise was
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12
likely to bring about respiratory symptoms and ventilatory function effects
within a period of one hour. Panel members concurred that it was not
possible to perform a fine tuning on the averaging tine associated with
this category of effects, and agreed that a one-hour averaging time represented
a satisfactory estimate of the exposure duration which should be considered
in a primary air quality standard aimed at protection of public health.
To some extent, a one-hour averaging time may provide a desirable addition
to the margin of safety, in that it may better protect actively exercising
persons.
VIII. Animal Toxicology Studies
A. Experimental Infection of Animals
Increased susceptibility to bacterial infection following ozone exposure
at 0.1 ppm is described by several investigators (Coffin et al. 1968, Ehrlich
et al. 1976, Gardner et al. 1974) in reports that do not fulfill the desi-
deratum of peer reviewed publications. These reports are, however, con-
sistent with a larger body of published evidence (Coffin and Gardner 1972,
Goldstein et al. 1971a, 1971b, Goldstein and Hoeprich 1972, Goldstein et al.
1974 and others) that establishes indices of infection or of mortaility
from bacterial infection as sensitive measures of the effect of ozone in
rodent lung. Additional stress such as heat, exercise or a combination with
other pollutants, according to some reports, may enhance the effect of
ozone on susceptibility to infection, and may thereby lower the ozone
dose at which the organism will be adversely affected.
The Panel agreed that these finding have definite human health implications
although an exposure level associated with such effects in humans may be
different. These reactions in mice represent basic biological responses to
infectious agents, and there is no reason to believe that pollutant induced
alterations of basic defense mechanisms in experimental mice would not
-------
13
occur in similarly exposed and challenged humans. However, the Panel is not
aware of epidemiological evidence that susceptibility to infection increases
in persons exposed to ozone and other photochemical materials. However,
the biochemical and cellular alterations described below for rodents suggest
that multiple epithelial and biochemical targets are perturbed by ozone
exposure. Since similar epithelial perturbations occur in humans when
viral infection precedes the onset of bacterial pneumonia, it is reasonable
to expect that chemical injury to respiratory epithelium will predispose to
infection. Ozone induced irritation of the major bronchi in man does
occur at ozone concentrations in the range of 0.25 ppm. Hence it is
possible that ozone damage at the level of respiratory bronchioles and
alveoli occurs in man as well as rodents, leading to promotion of sus-
ceptibility to bacterial infection of the lower respiratory tract. The
Panel observed that it may be particularly difficult to demonstrate these
relationships because bacterial pneumonia is a disease of low incidence,
occurring more in the winter season when oxidant concentrations are
typically low. It is possible that concentrations of ozone high enough
to injure macrophages do not reach the alveoli in man but do so in rodents
because of anatomic differences between human and rodent lungs. In this
case, the significance of the animal data on ozone-induced susceptibility
to infection lies in the demonstration that a measurable effect on a
biologically important system (defense against infection) occurs in rodents
at concentrations that also produce measurable responses in man (altered
mechanical function of the lung).
B. Morphological Abnormalities of the Respiratory System
A range of morphological effects was noted in association with experi-
mental ozone exposures of 0.2 to 1.0 ppm. These effects varied from
replacement of Type I with Type II alveolar cells, which are not known to
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14
have associated harmful consequences, to emphysematous changes and terminal
bronchiole and alveolar damage. These effects occurring after long-term
low concentrations, raise the level of suspicion that repeated or chronic
exposures have the potential for inducing similar effects in humans.
C. Biochemical Effects
The Panel observed that there is an impressive variety of biochemical
alterations associated with ozone exposures over the range of 0.1 to
1.0 ppm. The Panel judged that effects induced by 0.1 to 0.2 ppm exposures
are probably largely adaptive while effects caused by levels of 0.5 ppm
and greater have definite toxic potential. The Panel judged that these
biochemical changes are significant in demonstrating that there are
ozone-induced effects at cellular sites and organ systems distant from
the lung. While many of the biological reactions were in the nature of
a protective response and could possibly be prevented or reversed with
increased vitamin E levels in the lung or increased antioxidants at
other tissue sites, nevertheless they represented the organism's response
to stress. The Panel agreed that such perturbations in biological systems
may pose a health risk to the population of impaired or susceptible
individuals. One of the panel members noted that, in experimental
studies, Canadian subjects who manifested greater change in mechanical
function of the lung than in Los Angeles subjects also showed greater
hemolysis of red blood cells. These observations suggest that ozone
levels which produce lung function changes can also lead to biochemical
changes and other reactions of definite concern to health, and vice versa.
Overall, the Panel felt that there is not a sharp dividing line between
protective responses and potential for pathological consequences.
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15
D. Genetic and Teratogenic Potential
The Panel focused its attention on the reports of chromosomal abnor-
malities in peripheral leukocytes first observed upon exposure of intact
hamsters to 0.2 ppm ozone for five hours (Zelac, 1971)- One experimental
study of humans (Merz et al. 1975) found similar abnormalities in individual';
exposed to 0.5 ppm ozone. The significance of chromosomal aberrations in
peripheral blood cells has not been determined. Furthermore these studies
have not,been replicated, and the Panel agreed that there was insufficient
evidence to evaluate the long term implications of these reports. Although
confirmation of the results may suggest another category of ozone-induced
effects, the preliminary evidence does not suggest these effects occur at
drastically lower levels of exposure. It was further noted that genetic
consequences of population exposures to human mutagens are very difficult
to identify, even for such well recognized mutagens as ionizing radiation.
Veninga's observation (1967) of increased neonatal deaths and congenital
abnormalities in newborn mice was cited by the Panel as grounds for raising
the index of concern over the potential teratogenic effects of ozone. The
evidence for the mutagenic effect of ozone in bacterial systems and lung
tumorigenesis was also noted. The Panel observed that, were similar
findings demonstrated for food additives or pesticides, these substances
would undoubtedly be banned from use.
E. Performance and Behavioral Effects
Few experimental studies of performance and behavioral effects of
ozone have been reported and the Panel considered this category of effects
to be a neglected area of research both in animal and human ozone studies.
The effects of ozone and other oxidant exposure on athletic performance
(Wayne et al. 1967) and on motor vehicle accidents (Ury 1968) provide
epidemiological evidence for impact on performance in humans.
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16
F. Implications of Animal Toxicology Data
The Panel observed that the ozone dose which caused chronic tissue
damage in the lungs of experimental animals was much closer to ambient
concentrations than are the doses of carcinogens employed to produce tumors
in laboratory animals. The chronic respiratory diseases related to similar
tissue changes in humans were felt to be at least as important, from a
public health perspective, as respiratory cancer. Thus, it was noted
that the margin of difference between ozone concentrations that produce
serious toxicological effects in animals (as well as symptomatic and lung
'unction changes in humans) and ambient levels of ozone is much smaller
than for any other atmospheric pollutant. The Panel also emphasized that
there was a remarkable clustering and convergence of various toxicological
experimental human, and epidemiologically observed effects within a narrow
ozone concentration range, that is 0.2 to 0.6 ppm. These findings further
reinforce the judgment that there is not a sharp cut-off for ozone dose-
response relationship. The Panel hypothesized that exposures above maximum
observed background levels of 0.05-0.06 ppm may well be associated with
some increased health risk; this perception is based on the convergence
of various effects at concentrations minimally above background (less than
one order of magnitude).
The Panel pointed out that chronic disease effects of long term
ozone exposure in man cannot be quantitatively related to specific ozone
concentrations of short (hourly or daily) averaging times due to the long
period of disease induction and the varied exposures of individuals during
the period of induction. Epidemiological studies may establish relation-
ships between long-term ozone exposure and human chronic disease risk,
but we must rely on toxicological studies to guide us in quantifying the
ozone level that may induce chronic effects.
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17
VIII. "Ozone" vs. "Oxidant" Standard
The question was raised by the EPA staff whether the Health Panel felt
that an ozone standard or a standard for ozone and other photochemical
substances was required for protection of public health. The Panel agreed
that two characteristics of ozone exposure should be cited with reference
to public health protection: (1) ozone itself is a primary cause of most
of the health effects reported in toxicological and experimental human
studies and the evidence for attributing many health effects to this
substance alone is very compelling, and (2) ozone measurements should
be considered as an index for the complex of atmospheric photochemical
substances some of which are known to produce health effects which either
are not attributable to pure ozone, e.g., eye irritation, or which may
possibly augment the effects of pure ozone. The Panel judged that it was
not appropriate at this time to consider a primary air quality standard
for specific photochemical compounds other than ozone.
The Panel agreed that when ozone is measured specifically, in contrast
to measurements of total oxidants, it should be considered both as a
causal agent of adverse health effects in its own right and as an index
for the photochemical mixture which is associated with a broader range
of health consequences. Beyond this, the Panel did not reach consensus
as to whether the primary air quality standard should be expressed solely
as an ozone standard or as a standard for ozone and other photochemical substances,
Some Panel members were concerned that a standard for ozone alone would lead
some to dismiss epidemiological evidence relating health effects to "oxidant"
concentrations and further to discount the occurrence of symptoms and
effects not attributable to pure ozone. Other Panel members believed that
citing ozone as an index as well as primary agent in its own right would
obviate these problems.
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18
IX. Recommended Guidelines for the Protection of Public Health
In considering the margin of safety between concentrations that
represent a public health risk and the recommended standard, the Health
Panel called attention to several conslusions that were previously
stated:
1. There appears to be a finite probability of health risk
associated with population exposure to ozone concentrations
above observed maximum background levels, i.e., 0.05 to 0.06
ppm. Specifically, there is evidence from studies of ozone
and other photochemical oxidants for alterations of
mechanical function of lung in humans, for exacerbation of
asthma in humans, for alteration of ventilatory function in
school children, for induction of acute respiratory symptoms
in exercising children and young adults, for impaired athletic
performance in young adults. The Panel judged, as discussed
in the previous sections, that these effects may be induced
by short term exposures to ozone in the range of 0.15 to 0.25 ppm.
An unreplicated study of airway resistance in humans and
repeated studies of susceptibility to experimental respiratory
infection in animals further suggest the possibility of adverse
effects in some persons at short term ozone exposure of 0.10 ppm.
2. In contrast to most other atmospheric pollutants, there is a
convergence of experimental animal, experimental human, and
epidemiological studies demonstrating effects at relatively
low ozone concentrations, 0.15 to 0.35 ppm. These concentrations
represent a relatively small margin of difference between
observed minimum background levels and concentrations causing
increased health risks.
3. The implications of these demonstrated health risks are
significant to the overall health of human populations.
4. There is new evidence for biological reactions to combinations
of ozone with other commonly occurring atmospheric pollutants.
In reviewing the body of evidence on health effects, the Health
Panel concluded that there is no compelling reason to suggest a change
from the concentration defined by the existing primary air quality
standard, namely, 0.08 ppm. This conclusion was based upon the previously
cited Panel consensus that a variety of adverse effects are likely to
occur in some segments of the population from short-term ozone exposures
of 0.15 to 0.25 ppm, and upon other evidence that suggests, though less
conclusively, the possibility of effects at concentrations as low as 0.10
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19
ppm. The Panel recognized that this standard provides very little margin
of safety, for the reasons cited immediately above.
In considering the appropriate averaging time to be associated with
this recommended concentration limit, the Panel judged that a one-hour
exposure limit would provide some slight margin of safety for exercising
individuals, whereas two or three hour exposures at the same level would
tend to increase the delivered dose and thus raise the level of risk.
Thus the Panel concluded that a primary standard of 0.08 ppm for one
hour represents a level of exposure which would be consistent with pro-
tection of public health.
The issue of how many times the 0.08 ppm one-hour level could be
exceeded without increased health risk was addressed. The Panel agreed
that the level of health risk increased (1) in proportion to the hourly
concentration above 0.08 ppm, (2) in proportion to the number of hours
in one day above 0.08 ppm, and (3) in proportion to the frequency of
days in which hourly averages exceed 0.08 ppm, though the latter
conclusion was recognized to be quite judgmental and generally lacking
in confirmatory studies. Nevertheless, the Panel could cite no medical
reason to suggest that any exceedances of the standard were without
health risk.
In offering its recommendation of a 0.08 ppm one-hour exposure limit
as a guideline for the protection of public health, the Panel proposed
that this guideline be considered as a public health objective for
developing control strategies, rather than a signal for injunctive legal
actions. Excursions above the 0.08 ppm hourly limit should call for
evaluation of implementation strategies and not for crisis reactions
-------
that are disruptive of normal activities. As previously stated, the
level of health risk is judged to be proportional to the conceniration,
duration and frequency of exposures above the standard. The Panel is
not suggesting that small health risks are acceptable, but that occasional
excursions should be evaluated in the context of long tern goals and
the difficulty of reducing the primary emissions necessary to achieve
the standards. Overall, however, the Panel judges that there is now
mnre experimental and epidemiological evidence to be concerned with
ozone exposures above the standard than when the standard was originally
established, and that this concern should reinforce the determination
to implement the control strategies required to achieve the primary
standard.
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effect of exposure to 0^ and N0~ by exercise. (Abstract). Toxicol.
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Goldstein, E. and P. Hoeprich (1972). Influence of ozone on pul-
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Goldstein, E., W. Tyler, D. Hoeprich, and C. Eagle (1971a). Ozone
and the antibacterial defense mechanisms of the murine lung. Arch.
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Goldstein, E., W. Tyler, P. D. Hoeprich, and C. Eagle (1971b). Adverse
influence of ozone on pulmonary bactericidal activity of murine lung.
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Goldstein, E., D. Warshaver, W. Lippart, and B. Tarkington (1974). 0^
and N02 exposure. Arch. Environ. Health 28:85-90.
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D. C. Law, and A. Fischer (1975a). Experimental studies on human health
effects of air pollutants. I. Design consideration. Arch. Environ.
Health 30:373-378.
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lljckripy, ,J. D., W. S. Linn, J. G. Mohlor, C. F. Pedersen, P. Brnisacher,
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Health 30:305-.'WO.
Hackney, J. n., W. S. Linn, S. K. Karuza, R. n. Buckley, D. C. Law,
D. V. Bates, M. Hazucha, L. D. Penqelly and F. Silverman (1977).
Effects of ozone exposure in Canadians and Southern Californians. Arch.
Environ. Health 32:110-116.
Hazucha, M. (1973). Effects of ozone and sulfur dioxide on pulmonary
function in man. Ph.D. Thosis, McGill University, Montreal, Canada,
pp. 223.
Hdzucha, M. and D. V. Bates (1975). Combined effect of ozone and sulfur
dioxide in human pulmonary function. Nature 257:50-51.
Hazucha, M., F. Silverman, C. Parent, S. Field, and D. Bates (1973).
Pulmonnry function in man after short-term exposure to ozone. Arch.
Environ. Health 77:183-188.
Hmmicr, D. I., V. Hasselhlad, B. Portnoy, and P. F. Wehrle (1974).
Los Anqeles student nurse study. Daily symptom reporting and photochemical
oxidants. Arch. Lriviron. Health 28:255-260.
Kaqawa, J. and T. Toyama (1975). Photochemical air pollution: its
effects on respiratory function of elementary school children. Arch.
Environ. Health 30:117-122.
Kagawa, J., T. Toynma, and M. Nakaza (1976). Pulmonary function tests
in children exposed to air pollution. In Clinical Implications of Air
Pollution Research, A. J. Finkel and W. C. Duel, editors. Acton,
Mass.: Publishing Sciencinq Group, Inc., pp. 305-320.
Merz, T., M. A. Bcndor, II. n. Kerr, and T. J. Kullc (1975). Observations
of aberrations in chromosomes of lymphocytes from human subjects exposed
to ozone at concentrations of 0.5 ppm for G and 10 hours. Mutat. Res.
31:299-302.
Schoettlin, C- E. and F.. Landau (1961). Air pollution and asthmatic
attacks in the I os Anqoler, aroa. Public Health Repts. 76:545-548.
Ury, II. (1968). Photochnnicnl air pollution and automobile accidents in
Los Angplos. Arch. Environ. Health 17:334-342.
Vemnqa, T. (1967). Toxicity of ozone in comparison with ionizing
radiation. Strahlontherapie (Munich) 134:469-477.
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von Nieding, G., M. Wagner, H. Lollgen, and H. Krekeler (1977a). Zur
akuten wirkung von ozon auf die lungenfunktion des menschen. Proceedings
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von Nieding, G. and H. M. Wagner (1977b). Experimental studies on the
short-term effect of air pollutants on pulmonary function in man: two-
hour exposure to NO^, 0^ and SO
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TAB L
ALTERNATE FORMS
OF THE
AMBIENT AIR QUALITY STANDARD
FOR PHOTOCHEMICAL OXIDANTS
May 1978
Staff Summary Paper
Strategies and Air Standards Division
Office of Air Quality Planning and Standards
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
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ALTERNATE FORMS OF THE AMBIENT AIR QUALITY STANDARD FOR PHOTOCHEMICAL OXIDANTS
Summary
The present review of the primary and secondary ambient air quality
standard for photochemical oxidants includes an examination of the overall
form of the standard as well as a consideration of the appropriateness of
the concentration level and averaging time. The present form appears to
be simple and readily understood. By using the annual second highest
hourly average, an apparently simple means is available for determining
compliance. However, analysis shows that there are problems of sufficient
importance that alternate forms must be given serious consideration.
Because the annual second highest concentration is a single measurement
a large measurement error may occur and missing monitoring data may cause
the true second highest value to be missed. Further analysis reveals a
more fundamental difficulty which has not been as generally recognized.
Photochemical oxidant concentrations are subject to random changes in weather
and in daily precursor emission levels. Therefore, the average concentration
observed in any hour has a random aspect not recognized in the present form.
The standard concentration of 0.08 ppm is allowed to be exceeded once annually
but never more than once. However, if at a given level of precursor emissions
a certain meteorological condition can occur which will lead to oxidant
concentrations above the standard once in a year, then there is a definite
probability that these same conditions can occur two or more times in a year
and, therefore, lead to multiple violations in some years. The only way to
assure compliance with the present standard over all years in a given area
is to control precursor emission levels to the point that 0.08 ppm is never
exceeded, which is not a feasible expectation.
Thus, the current standard is more severe than apparent from first
inspection. As discussed in the report its seeming simplicity can lead to
inconsistent treatment from one AQCR to the next in deciding both compliance
and degree of emission control required. The report recommends that the
following form be adopted:
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X^ ug/m3 hourly average concentration with expected (average)
number of exceedances per year less than or equal to one.
This form represents the least possible departure from the present form
while fully taking into account the random statistical nature of factors
influencing oxidant concentrations. The recommended form allows for the
occasional occurrence in some years when more than one hourly average con-
centration will be above the standard (the number of such years is set by
the choice of the expected number of exceedances per year); it also provides
the basis for a consistent approach to decisions on compliance and degree of
emission control required. Use of the recommended statistical form requires
the use of a substantial portion of the air monitoring data collected in
a given year. Thus the statistical estimates that are needed to determine
compliance and degree of control are much less subject to measurement error
and statistical variation than the annual second highest concentration now
used.
Introduction
The present primary and secondary ambient air quality standards for
photochemical oxidants are both the same and may be stated as follows:
160 ug/cu. meter (0.08 ppm) maximum hourly average con-
centration not to be exceeded more than once per year.
The review of the oxidant standard now under way will not only include
an examination of the appropriateness of the concentration level and averaging
time based on our present knowledge of health and welfare effects but will
also consider the appropriateness of the overall form (expression) of the
standard. The form of the standard could be expressed in many ways, examples
of which are: the mean (geometric and arithmetic); expected value; percentile;
and some level never to be exceeded. However, since health effects are of
primary importance, the form must be compatible with current medical opinion
that adverse health effects occur when oxidant levels exceed certain levels
for short periods of time. Thus, any form of the standard selected must be
directed at minimizing excursions above the designated standard level.
While health and welfare effects are the primary considerations in
choosing the most appropriate form of the standard it is also important that
the form provide an adequate and clear basis for defining the overall quality
of ambient air it is desired to achieve. We, therefore, would want the form
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to be such that it: 1. adequately defines what must be measured to determine
compliance and measurements which can be made with the needed accuracy; 2.
provides clear, unambiguous criteria for determining whether an area is or
is not in compliance; and 3. provides a clear, unambiguous definition of
the air quality it is desired to achieve to serve as a target for the develop-
ment and verification of control strategies. This report examines the form
of the standard from this point of view and will provide a proper basis for
examining the impact of health and welfare effects on the form.
The Present Form of the Oxidant Standard
The current form of the oxidant standard has several advantageous features;
1. It seems to be simple and readily understood. 2. It reflects medical
opinion that protection should be provided against the highest levels likely
to be encountered in an area when brought under control. 3. It provides in
the annual second highest hourly average concentration, a simple, clear indi-
cation of the measurement to be made and a clear criterion for determining
compliance. However, as the analysis in this section will show, there are
problems with the current form which are of sufficient magnitude that alter-
native forms should be given serious consideration.
Two aspects of the present form of the standard have been criticized by
workers in the field and are brought out in the recent petition of the
American Petroleum Institute (API) for review and revision by EPA of the
oxidant standard. The two concerns stem primarily from the fact that the
standard focuses on a single measurement for determining compliance, the
annual second highest hourly average concentration. The petition points
out that Air Quality Control Regions (AQCR) differ widely in the completeness
of their monitoring data over a given year. Because of missing data the
probability of capturing the actual second highest concentration can vary
from as little as 1% to as high as 99% from one AQCR to the next, depending
upon the data retrieval rate. This can result in underestimation of control
levels needed on man-made emissions. In some areas a more serious result
would be the erroneous judgment that the areas are in compliance with the
standard when, in fact, they are not.
The second concern is that the second high is a single measurement and,
therefore, bears the full brunt of experimental error. The petition suggests
this error may be almost equal in magnitude to the second high itself at the
0.08 ppm level.
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The effects of these problems can be reduced by improved monitoring
equipment and procedures. They can also be reduced substantially by changing
to a form which requires the use of more of the available data to develop a
more "robust" statistic, that is, a statistic whose estimates have lower
variance or are less subject to random error. Examples might be: the expected
(or average) value of the second high, the expected (or average) number of
exceedances of the standard, the arithmetic mean of the hourly averages, or
the geometric mean.
Further consideration of the form of the present standard, however,
shows that it has a more fundamental problem than those discussed in the
proceeding paragraphs and one which has not been generally recognized. The
present form does not provide a clear, unambiguous definition of the air
quality it is desired to achieve, and, therefore, does not provide a clear
target for the development of control strategies and their verification.
The present standard appears to establish as a target a quality of ambient
air over an AQCR such that one hourly average concentration in a given year
may exceed 0.08 ppm but never more than one. This is a situation, however,
which does not appear to be feasible. There is no level of control of oxidant
precursor emissions which will yield a situation in which the standard can
be exceeded once in some years but never more than once. Hourly average
oxidant concentrations are subject to the random changes in weather and
in emission levels. If at a given level of precursor emission control a
certain meteorological condition can occur which will lead to oxidant con-
centrations above the standard once in a year, then there is a finite
probability that these same conditions can occur two or more times in a
year and, therefore, lead to multiple violations in some years. In this
situation the area will comply with the standard some years and be out of
compliance in other years.
For example, if under a given level of emissions the probability any
given hourly average oxidant concentration will exceed 0.08 ppm is 1 in
8760 (the number of hours in one year), the percentage of years 0.08 ppm
would be exceeded a given number of times is shown in Table 1. In 74 years
out of 100, the AQCR in question would be in compliance with the standard
(either one or zero exceedances), whereas in 26 years out of 100 it would
not be. On the average, the AQCR would violate the standard about once every
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TABLE 1
VIOLATIONS PER YEAR WHEN STANDARD EXCEEDED AN AVERAGE OF ONCE PER YEAR
NUMBER OF TIMES
STANDARD EXCEEDED
IN A GIVEN YEAR
0
1
2
3
£4
PERCENT OF YEARS
OCCURRING*
37
37
18
6
2
CUMULATIVE
PERCENT
OCCURRENCE
37
74
92
98
100
'ASSUMES INDEPENDENCE OF HOURLY AVERAGES AND UNIFORM PROBABILITY OVER
ALL HOURS
-------
four years. The average number of exceedances per year over a number of
years is one in this example (see Note #1). Although the above numbers
are not fully applicable to real situations, owing to seasonal and diurnal
variations and interdependence of hourly averages, they do illustrate the
principle involved.
The only way to assure compliance with the present standard over all
years in a given area is to control emission levels to the point that
0.08 ppm is never exceeded. Thus, both from the point of view of compliance
and emission control, the present standard is fully equivalent to a standard
in which the hourly average concentration 0.08 ppm is never to be exceeded.
The present standard requires, therefore, a greater level of control than is
apparent from superficial inspection of its form. It seems unlikely that
this situation was intended by its formulators. This is the reason for saying
the current form seems to be simple and easily understood when its advantages
were listed at the beginning of this section. The statement of the standard
is straightforward, but its true meaning is understood only when the stochastic
or random aspect of oxidant concentrations is appreciated.
From the proceeding arguments it is clear that the present form has
difficulties of a fundamental nature. The end state of overall air quality
the standard appears to define is not realizable. In fact, the standard can
only be satisfied by an end state in which exceedances never occur.
This latter point has not been fully recognized in establishing guide-
lines for developing emission control strategies for meeting the standard.
For example, if, for the purposes of this discussion, it is assumed the
current Part 51 Guidelines for calculating control levels needed for com-
pliance give correct results, the level of overall air quality that would
be attained in a given area is such that the area could be in violation
(more than one exceedance per year) 50% of the succeeding years. The present
practice is to apply Appendix J (or Proportional Rollback) to the second
highest hourly average observed in a base year to calculate the degree of
control needed to make 0.08 ppm the second highest value. However, because
the hourly oxidant values are subject to the random behavior in weather patterns
and daily emissions, the observed second highest values will tend to vary
from one year to the next. The potential impact of this variation on the
calculation of required control levels is shown in Figure 1.
Here it is assumed that the AQCR under consideration has an air quality
such that the most probable value of the second highest concentration is 0.18
ppm. The observed second highs in any year around this most probable value
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FIGURE 1
EFFECT OF STOCHASTIC BEHAVIOR OF SECOND HIGH CONCENTRATION ON APPARENT
AMOUNT OF CONTROL NEEDED AND VIOLATIONS OF STANDARD AT CONTROL LEVEL
Amount Control for No Violations '
Distribution I
of second high
concentration^
0.08
0.18
0.18
note: Shaded area represents fraction of years standard violated
whpn farnof- rnntrnl 1 oval ^«»/-w«/J
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8
are represented by the probability density function centered about 0.18 ppm.
The distribution functions shown are purely hypothetical and only serve
to illustrate the stochastic (random) behavior of the annual second high.
The top illustration in the figure shows the situation in which data for
only one year are available and the most probable value of the second
high was observed in this base year. The line marked "apparent control
needed" divided by 0.18 ppm (the observed second high) gives the amount of
control required by the proportional rollback method. If it is assumed that
this level of control shifts the distribution in a manner such that the
most probable second high would be at 0.08 ppm, then it is seen that in half
the years the second high will be above 0.08 ppm and the standard will be
violated half the years. This would be approximately the situation for
most AQCR's having this distribution of second high values.
The middle illustration shows the outcome if the observed second high
was on the high side of the distribution. In this case a higher
level of control would be calculated. But there still would be some years
in which the standard is violated. In the bottom illustration the observed
second high is below the most probable value. A lower level of control is
calculated and the resulting air quality will lead to violations in excess
of 50% of the years. Thus, the current form, by focusing on the second
high hourly average, has led to recommended procedures that are not likely
to lead to compliance and, furthermore, can give rise to unequal treatment
of AQCR's having the same air quality.
The top illustration in Figure 1 also shows the degree of control that
would be required to bring the AQCR into full compliance, that is the over-
all air quality in which no exceedances of 0.08 ppm occur. This is, as seen,
a higher level of control than would be required through use of the observed
second high in any one year.
The situation depicted in Figure 1 is most directly applicable to the
situation in the early 1970's when implementation plans were first being
formulated. At this time the base year was given as 1971 and, generally,
there was little data from other years to modify the second highest value.
The most recent guidelines (Guideline Series, OAQPS NO 1.2-047, January 1977)
allow the use of the second high concentration from one year if data from
other years is not available, but recommends using the highest of the second
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high values from three ormor-e years when available. When applied, this
procedure tends to favor the case shown in the middle illustration of
Figure 1. Even in this case there will tend to be some years in violation
and, overall, the effect on different AQCR's will be uneven. Differences
will be greatest when AQCR's use different numbers of years to determine
the second high. Those which use the smallest numbers of years will tend
to have relatively more lenient control requirements.
Other approaches have been suggested which may provide more uniform
treatment. R. Larsen has suggested the (average) annual maximum hourly
average could be used for calculating the required degree of control. But
this measure does not flow as naturally from the standard as does the
second high, and there will be some years in which the standard will be
violated. Larsen estimates 1 in 8 years will exceed the standard more than once
if the annual expected maximum is used as a "design value" to calculate required
control. The method, therefore, does not lead to an overall air quality which
will fully meet the implicit requirements of the standard.
Alternative Forms of the Oxidant Standard
From the previous discussion it is clearly worthwhile, in reviewing
the potential impact of the current understanding of health and welfare
effects on the form of the standard, to consider alternatives which avoid
the problems inherent in the current form. To provide a clear, unambiguous
definition of the air quality which will provide the desired protection of
the public health and welfare it will be necessary that the form take into
account the stochastic nature of ambient concentrations of oxidant. Forms
meeting this requirement will generally define a statistic that is estimated
from a significant fraction of the total data base. The measured statistic
will be more robust than the second high and, therefore, not as sensitive to
missing data and measurement error.
An exception is the nonstochastic form: 0.08 ppm hourly average never
to be exceeded. This form provides a well defined end state and a simple
test of compliance and is, therefore, acceptable in these respects. However,
the maximum possible ozone level in an AQCR is infrequently observed (the
maximum value observed in a given year would typically be below this value),
and would need to be estimated in some way in order to use currently available
methods for calculating degree of control needed.
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10
Table 2 lists several alternate statistical forms each of which
unambiguously defines a desired end state of overall air quality. The
forms shown were chosen to parallel the present standard in limiting
exposure to extremal values of the hourly average oxidant concentration.
The first five forms do this directly, the last two indirectly. There
should be no difficulty in defining the appropriate statistical forms
should medical opinion change concerning the type of protection needed.
The first alternative departs least from the present form. By
placing the number of exceedances on an expected or average value basis
it avoids the pitfalls of the present standard. Under the statistical form,
years in which the 0.08 ppm hourly average was exceeded more than once
would not be considered in violation of the standard unless the estimate
of the expected number of exceedances was greater than one. Setting the
expected exceedances at one is roughly equivalent to the situation depicted
in Table 1 (see Note #1). We would, therefore, expect violations of the
present form (more than one exceedance per year) to occur on the average of
approximately once in four years if the alternate were adopted. Note also
from Table 1 that three or more violations in a year would occur an average
of approximately only once in every 12 years.
If it is considered that the excursions above 0.08 ppm would be too
frequent with the expected number of exceedances set at once per year, the
number can be set at a more stringent value such as 1 in 5 years. Thus
EPA has two parameters, the concentration level and expected number of exceedances,
which can be adjusted to obtain whatever level of protection is needed.
At the present time this general form is recommended over the others
in the table because it represents the least departure from the present form,
is easy to understand, and the expected number of exceedances can be readily
estimated from the distribution of hourly averages over one or more years
(see Note $2}.
An example of how health considerations enter into the form of the
standard is seen in the following variation of the recommended form:
0.08 ppm daily maximum hourly average with expected exceedances per year
less than or equal to one. This form would be preferred if medical opinion
shifted from the current emphasis on hourly average concentrations to
concern about maximum daily hourly average concentrations.
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11
TABLE 2
ALTERNATE STATISTICAL FORMS OF OXIDAHT STANDARD
• 0.08 ppm HOURLY AVERAGE WITH EXPECTED NUMBER OF EXCEEDANCES PER
YEAR LESS THAN OR EQUAL TO ONE.
• 0.08 ppm-HOURLY AVERAGE WITH 90% PROBABILITY (CONFIDENCE) THAT THIS
CONCENTRATION WILL NOT BE EXCEEDED IN ONE YEAR.
e 0.08 ppm HOURLY AVERAGE NOT TO BE EXCEEDED ON THE AVERAGE BY MORE
THAN 0.01% OF THE HOURS IN ONE YEAR.
• 0.08 ppm ANNUAL EXPECTED MAXIMUM HOURLY AVERAGE.
• 0.08 ppm ANNUAL EXPECTED SECOND HIGHEST HOURLY AVERAGE
• 0.0125 ppm ANNUAL AVERAGE.
• 0.0100 ppm ANNUAL GEOMETRIC MEAN.
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12
The second form in Table 2 also has two adjustable parameters and
has the desirable feature of directly displaying the level of confidence
that the given concentration level will not be exceeded in a given year.
However, the confidence level is not readily deduced from ambient air
data. At the present time, it would be necessary to use existing equations
developed from extreme value and order statistics which assume no inter-
dependence of the hourly averages. Since these assumptions are not correct
for hourly average oxidant concentrations the use of this form, or any
form requiring these assumptions, is not recommended at the present time.
If independence of hourly averages is assumed, a confidence level of about
37% would provide the same air quality as the first alternate form (see
Note #3).
The third form is essentially equivalent to the first but refers
directly to the distribution of hourly averages. Notice that in order
to avoid the problem of the present form it is necessary to talk about
average (or expected) percentage of exceedances. This form is considered
less desirable than the first alternate because using a percentage figure
forces the use of a very small number, such as the 0.01% in the illustration.
There will be less intuitive grasp of the effect of this number of years
(the first form). The third and the first forms, as stated in the table,
give roughly equivalent protection (see Note #4).
The next two forms each involve a single parameter and thus provide
less flexibility than the preceeding forms. As in the case of the second
form in the table, they also require the assumption of independence of hourly
average concentrations if their values are to be estimated from hourly
average ambient air data. The use of an expected or average value results
in two distinct air quality end states for these two forms. Based on the
discussion in the last section, an AQCR meeting the expected maximum value
standard would (assuming independence of hourly averages) violate the
present standard an average of 1 in 8 years, while an AQCR meeting the
expected second high form would violate the present standard an average
of every other year. If the two forms were based on observed maximum
or second high values in a given year, the only way either standard could
be met consistently year after year would be to achieve an air quality where
0.08 ppm would never be exceeded. This is, of course, the problem with the
present standard. In fact, the form 0.08 ppm not to be exceeded by the
second highest hourly average in a given year is equivalent to the present
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13
form of the standard.
The final two forms are included to bring attention to the suggestion
which has been made occasionally that mean values be used in the oxidant
standard in place of extremal values because the former use all the avail-
able hourly average data. They are, therefore, much more robust than
forms based on extremal values. The presumption is that there exists a
correlation between the extremal values and mean values of hourly averages.
Supporting data has been advanced to show this to be the case. While good
correlations may exist, it would be preferable that the standard reflect
the type of protection desired from health and welfare effects. Present
medical opinion is that protection should be directed against the excur-
sions in oxidant concentrations rather than at maintaining average levels
below some value. Thus the standard should be based on minimizing excur-
sions of the highest ozone concentrations above certain levels. The use
of standards based on extremal values would not prevent the use of cor-
relations between average values and extremal values as a means of developing
control strategies or confirming compliance with a standard based on extremal
values.
Application of Statistical Forms
An understanding of how alternate statistical forms such as the first
form in Table 1 might be used in practice can be obtained from examining
three potential problems with their use which have been suggested. The
first is that year to year variations in weather and emission levels will
make it difficult to obtain a stable estimate of the statistic. This
difficulty applies to any statistic whose yearly value must be estimated.
The second highest oxidant value observed in a given year is, in fact,
more subject to this source of variance than the alternate statistical
measures given in Table 2. For example, even if general weather patterns
and emission levels did not shift from year to year, the observed second
high would change from year to year due to fluctuations in weather and
emissions within the year to year patterns. There would be an additional
source of variation arising from lack of a complete data set and the effect
of random experimental error on a single observation.
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14
In contrast, if the first form in Table 2 were adopted, the overall
air quality for a given AQCR could be characterized by that hourly average
concentration level for which the expected number of exceedances was one.
It would not be correct to estimate this statistic by finding the second
highest oxidant value for that year. Ambient air data would be plotted on
a suitable probability paper and a "best line" fitted to the data (see
Note #2). The concentration above which 1/8760 of the data for one year
lie is read from the line. The expected exceedance of this concentration
is once per year. The concentration corresponding to an expected exceedance
of one determined by the above procedure would be expected to show relatively
small changes from year to year unless there were significant shifts in
overall weather and emission patterns.
The present guidelines use year to year data to define a highest
second high for a period of several years. This highest second high is
also subject to statistical variance as well as trends over time in weather
and emission levels. It would be possible to apply this same procedure to
the forms in Table 2. For example, the highest concentration corresponding
to an expected exceedance of 1 could be determined from such concentrations
for several consecutive years. In reducing the effects of weather and emissions
variations within any given year by using more of the available data, the
estimated oxidant concentration (expressed in any of the forms in Table 2)
would be more reliable and statistically valid because within year variations
would be adjusted out. Subsequently, longer-term (year to year) changes in
weather and emissions levels also could be separated out of the statistic.
The improved statistical forms would therefore allow more accurate tracking of
progress in improving air quality.
The second potential problem suggested is that the statistical forms in
Table 2 do not provide a positive indicator that an AQCR is out of compliance.
This consideration is only potentially applicable to situations in which an
AQCR is close to compliance since the statistical forms would easily detect
regions significantly out of compliance. Before considering the statistical
forms it will be worthwhile to examine the limitations of the trigger provided
by the second high concentration. First, the absence of an incomplete data
base and experimental error may cause the second high value to indicate
compliance when an AQCR is not in compliance. Second, experimental error
can also lead to a false indication that the AQCR is in compliance. These
problems are reduced with the more robust measures provided by the statistical
forms.
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15
Probably more important is the year to year variation in the second
high due to "within year" and "year to year" variations in weather and
emissions. As discussed in earlier sections, even after emission levels
have been brought to the levels indicated necessary by the second high
value in a base year or over several years, the AQCR will continue to
violate the standard in some years. If further control action is initiated
after each violation (two exceedances in a year), violations will continue
to occur after each new control action until finally a level of control is
reached in which the 0.08 ppm level is never exceeded. This would be overkill
in terms of the air quality which was desired but would be the inevitable
consequence of triggering control action every time the 0.08 ppm was exceeded
twice in one year.
In actual practice this is not likely to happen. If the control levels
which have been calculated from the base year(s) have been reached and a
given year is mildly in violation (say three exceedances), control officials
recognizing the variability of oxidant concentrations likely will wait to
view the number of violations occurring next year or over several years
before requiring further control. If these years also show violations
they would probably impose further controls. If violations occurred rela-
tively infrequently in succeeding years the officials would probably be
disinclined to act further since a substantial amount of additional control
might be required to totally eliminate violations. Thus, the positive
trigger provided by the present form would probably not be fully acted on
by knowledgeable control officials. Such discretion on the part of control
officials would not be required with the new form of the standard which would
correctly allow for occasional excursion above the standard.
With regard to the alternative statistical forms, it is possible to
make these into as positive triggers as desired. The statistic in eacl*
of these forms can be estimated solely from the hourly average data within
a given year using the approaches discussed in preceeding paragraphs. If
the estimate indicates a violation,that year could be established as a new
base year and further controls imposed.
However, even though these estimates are less subject to variation
than the observed second high it would still be unwise to use the yearly
estimates of these statistics alone as positive triggers. Since the yearly
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16
estimates are only estimates of the real statistic corresponding to the
overall air quality for a given level of control, it would be better to
establish confidence intervals around these estimates. If a predetermined
confidence level 1s exceeded, further control action could be taken.
These procedures would only be needed when the region was close to com-
pliance. At this point, each year of additional data would build increased
confidence in the estimate of the compliance statistic and provide a more
reliable test of departure from compliance. There is, therefore, no
Inherent problem with the alternate statistical forms as triggering mechan-
isms for control action.
The third potential problem area is concerned with how to handle an
AQCR with multiple sampling sites. The most stringent method would be to
pool all hourly averages from all sites in determining compliance by whatever
form chosen. In this case an area with several monitors experiencing an
oxidant episode spread relatively uniform over the region would almost
certainly be in violation. Since it is the same episode over the area this
procedure seems rather strict. In the case of the third, fourth, and fifth
forms in Table 2 there would be no convenient way to apply this procedure.
With these forms, data from the different monitoring sites would in effect
be simply averaged.
The second alternate would be to pool all the data from all sites
in determining the probability distribution but calculate the statistics
on the basis of 8760 observations (the hours in one year). This would put
all the forms in the table on the same footing. But it would also dilute
the effect of the sites experiencing the highest ozone levels during an
episode.
A third alternate would be to apply the standard to each site separately.
In this way if the data from any one site in the area is in violation the
whole AQCR would be considered in violation. This alternate is intermediate
in effect between the two above methods. It appears to combine the positive
features of each and, therefore, seems the most reasonable. This alternate
1s recommended for use with the present standard in the most recent air
quality standards guideline. (Guidelines for the Interpretation of Air
Quality Standards, EPA-OAQPS-MDAD, February, 1977).
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17
Other concerns with statistical forms which have been expressed are
that they lack the simplicity and directness of the present form and, there-
fore, may not be as readily understood by the public and may present problems
in legal proceedings. However, it is clear that the form of the present
standard is flawed. If the present standard is applied as stated, an AQCR
will only attain full compliance when conditions are such that the standard
concentration will never be exceeded. This, as was shown, is a direct
consequence of the variable or random aspect of hourly average oxidant con-
centrations. This stochastic feature of oxidant concentrations can only be
taken into account by statistical forms such as those shown in Table 2.
These forms are also based on more robust statistics than the second high
and provide clear, unambiguous targets for compliance and the development
and verification of control strategies.
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18
Notes
1. Probability theory shows that if the probability that a certain
event will occur in a given trial is p then the probability, Pm,
that the event will occur m times in n repeated independent trials
is:
D _ n* _ _m /i _\n-m
P-- P (1'p) •
This equation is known as the binomial distribution. If it is assumed
that p(C) is the probability that the average concentration for any
hour of the year is greater than or equal the hourly average concen-
tration C (assumption of independence of hours), the probabilities
of 0, 1, 2, 3 exceedances of a given concentration in the 8760 hour
in a year can be calculated.
For example:
For no exceedances per year:
P = 876° ( i ,9, i x
M " J
0 0! 87601 W60 " 8760
1 8760
8760} = °'3679'
For one exceedance per year:
P - 8760' _ r * U1 - ]
1 1! (8760 - 1)1 ^8760MI 8760
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19
For two exceedances per year:
R7fin' i 2 1 8758
_ _ o/ou. / i \ /I _J \
2 " 2! (8760-2)1 V8760 8760;
87KQ i 8758
9 (1 - o^n) = 0.1840.
2 x 8760
The expected or average number of exceedances per year is obtained
by summinq each number of exceedances per year weighted by its
probability of occurance. Referring to Table 1,
Expected exceedances per year = 0.37 x 0 + 0.37 x 1 + 0.18 x 2
+ 0.06 x 3 + 0.02 x 4 + etc.
Thus the concentration which corresponds to p(C) = 1/8760 is also
the concentration with an expected exceedances/year of one.
2. The cummulative distribution of hourly averages over one or more years
1s defined as a function f(C) where f(C) is the fraction of hourly
averages which exceeds the concentration C. This function can be
estimated from a collection of one or more years of hourly average
concentration data by standard plotting techniques.
If the standard concentration level is 0.08 ppm then the relative
frequency f(0.08) multiplied by 8760 is the average or expected
number of exceedances per year of the standard concentration. This
follows directly from the definition of f(C). This frequency, f(C),
is read from the "best fit" line drawn through a plot of hourly
average concentration vs. frequency data.
Another useful statistic is the concentration which corresponds
to exceedances/year of one. In this case the concentration corres-
ponding to f(C) = 1/8760 is read from the best fit line.
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20
Recent studies suggest that the log normal distribution function
does not give a good fit to the distribution of hourly average oxidant
concentrations, but the Weibull distribution does. In any case, if a
statistical form of the standard is adopted, detailed guidance will
need to be given on how to treat the air monitoring data to obtain
the needed statistics.
3. The probability that a given concentration level will not be exceeded
1n a given year corresponds to PQ of the binomial distribution given
under Note 1. As shown, for p(C) = 1/8760 the expected exceedances/
year is one (corresponding to the first alternate form of the standard
in Table 1), and for p(C) = 1/8760, PQ = 0.37 (corresponding to the
second form of the standard in Table 1).
Note that calculation of P_ assumes independence of hourly average
concentrations. At the present time there are no formulas for exactly
calculating P for the nonindependence case.
4. By the definitions in Note #2, 100 x f(C) is the per cent frequency
to be used in the third alternate form. f(C) = 1/8760 for the concen-
tration with an expected exceedances/year of one, and, therefore,
1/8760 = 0.0114% = approx. 0.01%.
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'•pre*^
'/ 1 \ y*
TAB Q
THE USE OF JUDGMENTAL
PROBABILITY DISTRIBUTIONS IN
SETTING NATIONAL AMBIENT AIR
QUALITY STANDARDS FOR OZONE
By:
Daniel J.Quinn
Prepared for:
U.S. Environmental Protection Agency
Research Triangle Park
North Carolina
SRI Project 8780
SRI International
333 Ravenswood Avenue
Menlo Park, California 94025
(415) 326-6200
Cable: SRI INTL MPK
TWX: 910-373-1246
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Abstract
This report documents the conduct of interview sessions held with
health experts for encoding their judgmental probability distribution
over the health effects level of ambient ozone concentration. The
interview sessions were conducted by EPA staff in conjunction with a
review of the primary National Ambient Air Quality Standard for
ambient ozone. The encoding techniques used are documented in a
companion report, The Use of Judgmental Probability in Decision Making
by Daniel J. Quinn and James E. Matheson.
Introduction and
This report documents work performed by a member of the Decision
Analysis Department of SRI International in response to an EPA
task-ordering agreementUJ^ The work was~~carried out to assist EPA in
it-.y distributions on the health effects of
photochemical oxidants as measured by ambient ozone concentrations and
to verify the validity of the techniques used. Motivation for this
project derives from SPA's review of the National Ambient Air Quality
Standard (NAAQS) for ambient ozone.
The Clean Air Amendments of 1970 [2] give the Environmental
Protection Agency responsibility for setting NAAQS for a number of
pollutants. The 1977 Clean Air Amendments [3] require that EPA review
its current NAAQS for a number of pollutants by 1980. The EPA staff has
developed an explicit formal procedure for incorporating the judgment of
health experts into the setting of standards. [U] This procedure
requires the encoding of probability distributions from health experts
concerning the health effects of ambient ozone concentrations.
The Decision Analysis Department of SRI International has had
extensive experience in the practical aspects of encoding probability
distributions, and was asked to assist EPA staff in the probability
encoding procedure. This report documents that work. A companion
report, The Use of .Judgmental Probability in Decision Making (Reference
5) , contains a general discussion of the concept of judgmental
probability, including its definition, past applications in government,
and a procedure for its assessment developed at SRI International. The
term 'subjective probability' has often been used; we prefer 'judgmental
probability,' or, even better, Just 'probability.'
This report is divided into three sections. The second section
briefly indicates the role of judgmental probability distributions in
setting air pollution standards. It contains a brief justification of
the use of judgmental probability (further information is contained in
Reference 5, which was prepared concurrently). The third section
discusses the three encoding sessions participated in by SRI and offers
some general observations concerning the encoding sessions.
The distributions encoded are a reasonable representation of the
judgment of the health experts consulted. They represent a great
1
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improvement in the communication of that state of judgment over other
methods.
The Use of Judgmental Probability Distributions in Setting
Air Quality Standards
The results of the encoding sessions are documented in the next
section. However, before presenting the results, it is useful to
discuss the role of Judgmental probabilities in setting air quality
standards.
The social regulation of pollutant levels is a complex process, one
requiring technical and scientific, as well as political, judgment. In
the absence of perfect information about health effects of pollutants,
and given the need to extrapolate to the population as a whole from
limited situations where objective knowledge is available, the encoding
of experts' probability distribution can play a useful role.
The Clean Air Act states:
National primary ambient air quality
standards...shall be ambient air quality standards,
the attainment and maintenance of which in the
judgment of the Administrator, based on [air
quality] criteria and allowing an adequate margin of
safety, are requisite to protect the public
health.[6]
Supporting material to the Act states:
An ambient air quality standard, therefore, should
be the maximum permissible ambient air level of an
air pollution agent or class of such agents (related
to a period of time) that will protect the health of
any group of the population.[7]
To set an ambient air quality standard, according to the Act and
its supporting material, one needs to know the level of a given air
pollution agent that will cause health effects in the most sensitive
group of the population. Because this level is uncertain, the standard
should provide an adequate margin of safety.
There are thus two types of judgment needed to set a standard:
judgment about the health effects level and the uncertainty in that
level, and normative judgment, to define an 'adequate' margin of safety.
Both scientific and normative judgment need to be brought to bear on the
definition of health effects.
The Air Quality Criteria document (Reference 8) reviews available
scientific knowledge bearing upon che effects of photochemical
oxidants/ozone on human health and welfare. The air quality criteria
document is reviewed by the scientific community.
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Unfortunately, knowledge of health effects i3 never complete ~
available scientific knowledge is not sufficient to unambiguously set a
standard that will protect the health of the most sensitive group of the
population, yet be as high as possible so as not to be unduly
restrictive. Available data must be interpreted and related to the
specific question of an ambient health effects standard.
The use of probability distributions on the health effects level
(related to a period of time) encoded from health experts, is intended
to allow the maximum use of the health experts' knowledge and Judgment
in this necessary proce.ss of integration and interpretation of data.
Judgmental probability distributions have the additional advantage of
being an unambiguously defined, quantitative, and concise way of
specifying the state of information and judgment of the health experts.
A judgmental probability distribution is a quantitative
representation of a person's current state of knowledge; it is the
distillation of all the knowledge the expert would bring to bear about
the given effects level and the uncertainty in that effects level, if he
or she had to act today, based upon the information at hand. This
information is summarized in the air quality criteria document.
The alternative to using judgmental probability distributions to
convey the state of information of an expert is to rely on verbal
formulae such as 'highly likely' or 'there is a small chance.1 In the
present case, the use of judgmental probability distributions has
enabled a much more precise communication of the experts' judgment.
Several factors contributed to this result:
o The precision and lack of ambiguity of the
probability curve as compared to verbal
formulations,
o The focus of the encoding sessions on results
relevant to the standard-setting procedure,
o The interviewing of the health experts separately,
allowing them to express their true judgment without
interferences resulting from the social dynamics of
a group discussion.
EPA has proposed a methodology that includes using judgmental
probability distributions to allow the scientific judgments of the level
and its uncertainty to be made in precise, unambiguous fashion, so chat
this data may be of maximum use to EPA when it sets the standards. This
methodology is explained and justified in Reference 4. Reference 5
discusses the justification for using judgmental probability
distributions, and documents past uses of this means of quantifying
expert judgment in both the public and private sectors.
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Conduct of the Encoding Sessions
This section documents the procedures used during the actual
encoding sessions. The results obtained, as well as the precise
definition of the health effects level encoded, are in Reference 4.
A total of nine experts (listed in Reference Uj were interviewed in
the standards-setting procedure. This section is based on observations
made during three representative sessions that were attended by Dr.
Daniel J. Quinn of SRI International.
The lead role in probability encoding sessions was taken by Mr.
Thomas Feagans of EPA. For two sessions, he was assisted by Dr. William
Biller, an EPA contractor. Dr. Quinn1s function was to observe and
assist in the probability encoding task, and to assure that proper
techniques (see, for example, References 5 and 9) were being followed to
assure chat the judgmental probability distributions corresponded to the
best judgment of the experts interviewed. It wag deemed sufficient to
have Dr. Quinn's assistance at three of the nine interviews.
The structure of the encoding session was designed using the
accumulated experience of the Decision Analysis Department of SRI
International. This group has been instrumental in the development and
application of the concept of judgmental probability distributions over
the past 12 years [5, 9f and 10]. The assessment of probability
distributions is an integral part of the practice of decision analysis,
a methodology that has been applied to a number of decisions involving
risk and uncertainty in complex environments in both the public [11] and
private [12] sectors. General principles to guide the encoding of
probability distributions are given in References 5 and 9. Reference 10
is a bibliography of literature concerning the encoding and use of
probability distributions. The application of decision analysis to
problems of concern to tne EPA is discussed in Reference 13.
The sessions followed the procedure described in Reference 5> The
process was divided into five phases, motivating, structuring,
conditioning, encoding, and verifying.
» . •
The motivating phase introduced the importance and purpose of the
probability encoding. It was stated that the expert should not include
a 'margin of error1 in his judgment; on the other hand, he should not
favor what has been unequivocally scientifically demonstrated over what
is most likely in view of current evidence. What was wanted was his
best current judgment regarding the actual health effects level.
>—
The structuring phase was especially involved, because the health
effects chreshhold, the quantity on which expert judgment was sought,
was particularly complex to specify. It was defined very carefully and
unambiguously. (See Reference U for the definition of the health
effects threshhold.)
The conditioning, encoding, and verifying phases were as described
in Reference 5.
-------
It is important to note that the subjects were not 'led by the
hand1 in any way. The interviewers were careful not to suggest values
that were 'good1 or 'bad.1 The subjects themselves provided the range
of values encoded and were comfortable with the'scale in which the
values were expressed. The subjects verified that the final probability
distribution obtained represented their best judgment, both by direct
examination and by confirming their acceptance of logical implications
of the distributions as discussed in Reference 5.
The experts were quite cooperative, and tried to make their
responses correspond to their true judgment.
The distributions encoded are a reasonable representation of the
judgment of the health experts consulted. They represent a great
improvement in communication of that judgment over other methods.
-------
References
[1] EPA Contract No. 68-02-2835 (9/21/77). SRI International
Internal Charge No. 6780-1.
[2] Clean Air Act, Section 109, 42 U.S.C.
[3] Public Law 95-95, August 1977.
[4] EPA Staff, "A Method for Assessing the Health Risks Associated
with Alternative Air Quality Standards for Photochemical
Oxidants, Strategies and Air Standards Division, Office of Air
Quality Planning and Standards, Office of Air & Waste
Management, U.S. Environmental Protection Agency, Research
Triangle Park, North Carolina (External Review Draft, January 6,
1978); a final version of this document is scheduled to appear
in May 1978.
[5] Quinn, Daniel J., and James E. Matheson, "The Use of Judgmental
Probability in Decision-Making," SRI Report, May 1978.
[6] Clean Air Act, Section 109, 42 U.S.C.
[7] Senate Committee on Public Works, A Legislative History of the
Clean Air Amendments of 1970, 1974.
[8] Oxidant/Ozone Health Effects Air Quality Criteria Document, EPA.
February, 1978.
C9] Carl S. Spetzler and C.-A. S. Stael von Holstein, "Probability
Encoding in Decision Analysis," Management Science, Vol. 22, No.
3, November 1975.
[10] C.-A. S. Stael von Holstein, "A Bibliography on Encoding of
Subjective Probability Distributions," unpublished manuscript,
SRI International, 1972.
[11] Representative applications of decision analysis in the public
sector have included the following:
1. Howard, Ronald A., James E. Matheson, and D. Warner North,
"The Decision to Seed Hurricanes," Science, 16 June 1972, Vol.
176, pp. 1191-1202. Letters appeared in Science, 23 February
1973, Vol. 179, pp. 744-747; and 14 September 1973, Vol. 181,
pp. 1072-1973.
2. D. Warner North and M. W. Merkhofer, "Analysis of
Alternative Emissions Control Strategies," in Air Quality and
Stationary Source Emission Control, a report by the Commission
on Natural Resources, National Academy of Sciences, National
Academy of Engineering, and National Research Council, prepared
for the Committee on Public Works, U.S. Senate, Serial Ho. 94-4,
U.S. Government Printing Office, #052-070-02783-5 (March 1975).
-------
3. North, D. Warner, Fred L. Offensend, and C. N. Smart,
"Planning Wildfire Protection for the Santa Monica Mountains:
An Economic Analysis of Alternatives," Fire Journal. January
1975.
4. Cazalet, Edward G., "Recommendations for a Synthetic Fuels
Commercialization Program," Vol. II of "Cost/Benefit Analysis of
Alternate Production Levels." Report submitted by the Synfuels
Interagency Task Force to the president's Energy Resources
Council, November 1975. Includes a decision analysis of
synthetic fuels commercialization program alternatives.
(Available from the U.S. Government Printing Office,
#041-001-00111-3, price $4.30.)
5. Barrager, Stephen M., Bruce R. Judd, and D. Warner North,
"The Economic and Social Costs of Coal and Nuclear Electric
Generation: A Framework for Assessment and Illustrative
Calculations for the Coal and Nuclear Fuel Cycles." Prepared by
SRI International for the National Science Foundation, March
1976. (Available from the U.S. Government Printing Office,
#038-000-00293-7, price $2.05.)
6. Judd, Bruce R., et al., "Decision Analysis Framework for
Future Electrical Planning," Vol. I of Electricity Forecasting
and Planning ReportT prepared by the Office of Planning and
Analysis, Energy Assessment Division, California Energy
Resources Conservation and Development Commission, November
1976.
7. Merkhofer, M. W., and D. J. Quinn, "Methodology for
Back-Contamination Risk Assessment for a Mars Sample Return
Mission," prepared by SHI International for the Jet Propulsion
Laboratory, Pasadena, California, April 1977.
[12] The SRI International Decision Analysis Department has assisted
dozens of corporations to make decisions involving major
committments of assets, such as capital expenditures,
acquisitions, and new product development.
[13] A philosophy and a methodology for making environmental
protection decisions, based upon the principles of decision
analysis, is found in:
Howard, Ronald A., James E. Matheson, and D. Warner North,
"Decision Analysis for Environmental Protection Decisions,"
prepared for the National Academy of Sciences, June 1977.
A copy of this report is enclosed. A general discussion of the
role of analysis vis a. vis expert judgment and policy making
decisions in public policy is in:
Barrager, Stephen M., and D. Warner North, "Analyzing the
Decision on Radioactive Waste Management," paper prepared for
the SPA workshop, "Issues Pertinent to the Development of
Environmental Protection Criteria for Radioactive Wastes,
February 3-5, 1977.
-------
TAB S
EXEa_rnvE OFF1CE OF THE PRESIDENT
COUNCIL ON WAGE AND PRICE STABILITY
726 JACKSON PLACE. N.W.
WASHINGTON. DC 2O5O6
OCT 1 6 1978
Honorable Douglas M. Costle
Administrator
U.S. Environmental Protection Agency
401 M Street, S. W.
Washington, D. C. 20460
Dear Mr. Costle:
The Regulatory Analysis Review Group has completed its review concerning
the proposed revision to the national ambient air quality standards for
photochemical oxidants (the ozone proposal). On September 15 and 28,
respectively, I submitted for the Environmental Protection Agency s
public record a notice that this proposal had been selected ror review
and a list of the issues the Review Group expected to address. The
outcome of this- review is the enclosed report which I. request be placed
in the public record for this proceeding.
Sincerely,
Barry P. Bosworth
Director
cc: Members of Regulatory Analysis Review Group
Mr. Joseph Padgett (MD-12), Director
Strategies and Air Standards Division
U.S. Environmental Protection Agency
Research Triangle Park, N.C. 27711
Environmental
Protection Agan
r!«« O
DEC 20 19TP
"LIBRARY
-------
Environmental Protection Agency's
Proposed Revisions to the National
Ambient Air Quality Standard for
Photochemical Oxidants ]/
Report of the
Regulatory Analysis Review Group
Submitted by the
Council on Wage and P_Hce Stability 2J
QCT 1 S 1978
I/ Federal Register. June 22, 1978 (43 FR 26962-26985).
2/ The Council on Wage and Price Stability is an organization created by
the Council on Wage and Price Stability Act (P.L. 93-387) within the
Executive Office of the President, The authority of the Council to inter-
vene in governmental rulemaking and ratemaking proceedings, conferred by
Section 3(a) of the Act, has been delegated to the Director of the Council
(see 40 ££52882).
-------
The current primary and secondary national ambient air quality standards
for photochemical oxidants are 0.08 parts per million (ppml for a one hour
average, not to be exceeded more tfian once a year.
i/
EPA's proposed revision to these standards has the following key
provisions:
The standards are to be defined in terms of ozone rather
than photochemical oxidant.
The primary standard is to be changed to the proposed
level of 0.10 ppm for a one hour average, not to be
exceeded more than once a year on an expected value
basis (using a three year average of occurrences)..
The secondary standard is to remain at 0.08 ppm.
The primary and secondary ambient air standards become the target for
State Implementation Plans and the Federal Motor Vehicle Emissions Control
Program in controlling hydrocarbon and nitrogen oxide emissions (ozone results
from such emissions).
Sunnaarv
In developing its primary standard, EPA has pursued a methodology
that does not consider aggregate exposure to ozone; EPA has not
provided an adequate rationale for its crucial policy choices in
the application of its methodology.
EPA's decisions and judgments in applying its methodology have
pushed the standard in a direction that may be more stringent than
is necessary.
It Federal Register, June 22, 1978 (43 FR 269.62-Z69851.
-------
estimates the costs of meeting che 0.10 ppm standard to be
S6.9 - $9.5 billion per year; these costs are understated, and
more accurate figures indicate at least a doubling of EPA's cost
figures, to $14.3 - $18.8 billion per year.
An alternative methodological approach, focusing on likely
aggregate unhealthy exposure to ozone, indicates that the
marginal costs of EPA's proposed standard may be in the range of
$1,100 - $4,100 per reduced person-hour of ozone exposure, which
causes discomfort but is reversible and apparently has no long-term
debilitating effects.
There is little documented scientific support and none of the
balancing which appears required for the determination of the
secondary standard.
The absence of thresholds and of totally safe standards suggests
the need for a different methodology which focuses on che choice
among exposure levels and on the consistency of choices across
pollutant control efforts, other health efforts by government,
and general private behavior.
The following discussion supports these conclusions.
A. Setting the Primary Standard
The Regulatory Analysis Review Group (Review Group! agrees with EPA
when it states in the Proposal:
The Administrator recognizes...that controlling ozone to
very low levels is a task that will have significant impact
-------
_ 3 -
on economic and social activity. It is thus important that
the standard not be any more stringent than protection of
the public health demands.—
There are four important characteristics of ozone exposure. First,
for any given individual, there probably is not a sharp threshold effect
but rather a continuum, starting vith very minor physiological effects
and continuing through to major health effects. EPA has recognized this
when it echoes the National Academy of Sciences in concluding that
no clear threshold can be identified for health effect
due to ozone. Rather there is a continuum consisting of
ozone levels at which health effects are certain, through
levels at which scientists can generally agree that health
effects have been clearly demonstrated, and down to levels
at which the indications of health effects are less certain
and harder to identify. Selecting a standard from this
continuum is a judgment of prudent public health practice,
and does not imply some discrete or fixed margin of safety
that is appended to a known "threshold."!'
Second, this continuum of effects is not identical for all people but
'±J
rather varies with individual sensitivities, states of health, etc.
Thus, a sensitive person (e.g., an asthmatic) is likely to experience
any given health effect at a lower ozone concentration level than a less
sensitive person. Accordingly, there is no single continuum but rather a
series of continuums that extends from the most sensitive to the least sensitive
person in the United States.
Third, there is considerable uncertainty as to the location and shape
of these continuums — i.e., for an individual of certain characteristics,
2/ 43 FR 26965.
3/ 43 FR 26265.
4/ See U.S. E?A, "Summary Statement from the EPA Advisory Panel on Health
~ Effects or Photochemical Oxidants," January 1978, p. 3; and Strategies
and Air Standards Division, Office of Air Quality Planning and Standards,
U.S. EPA, "A Method cor Assessing the Health Risks Associated with Alternative
A,-. rt.,an-« «i.9m«srrf«." Julv 1978. no. 2-25 co 2-27.
-------
- 4 -
at what ozone concentrations will a given health effect be experienced?
Finally, there is considerable meteorological variability in ozone
concentrations over time. This variability is best expressed by a probability
distribution of ozone concentration levels for a given geographical area.
EPA's approach to setting the ozone standard might be characterized as
follows: From the continuum of effects, EPA has focused on a particular point
as defining the onset of health effects. EPA has relied on the advice of its
scientific experts to define this point with respect to four categories
of health effects: impaired pulmonary function, chest discomfort and airway
resistance, decreased resistance to infection, and aggravation of chronic
5/
respiratory disease.
Next, EPA has tried to determine the ozone concentration level at which
this critical point (the onset of health effects) occurs. Here, EPA has used
—I
two approaches: It has examined (with the assistance of a panel of experts )
the existing toxicological and epidemiclogical literature on ozone. From
that literature, EPA has concluded that "the demonstrated human effects"
IJ
levels..-vary from 0.15 ppm to 0.30 pom."
Further, it has asked a different (but somewhat overlapping) panel to
provide its best judgment as to the ozone concentration level at which
health effects would be felt by "those persons who are more sensitive than
99 percent of the sensitive group [asthmatics and others with breathing
difficulties and individuals engaging in vigorous exercise] but less
i/
sensitive than 1 percent of that group." The panel provided median estimates
5/ 43 FR 26964.
6/ "Summary Statement from the EPA Advisory Panel,"_op. cit...
Tj 43 FR 269.66.
8/ 43 FR 26966.
-------
- 5 -
of 0.15-0.18 ppm as the point at which health effects are likely to occur,
for the four categories of effects, for the 99th percentile individual. The
panel also provided a full probability distribution on the likelihoods, for
this 99th percentile individual, of the health effects occurring at Lower or
higher ozone concentrations.
Next, EPA has characterized the time pattern of ozone concentrations
with a particular probability distribution, the Weibull distribution. With
specific parameters for that distribution, EPA can, for alternative ozone
standards, determine the probability of the occurrence of ozone concentration
at or above any particular level.
Accordingly, EPA has combined the Weibull distribution of occurrences with
the 0.15 ppm level at which, it argues, "health effects are virtually certain,"
to obtain the likelihood of health effects being experienced, at alternative
10/
ozone standards. EPA has also combined the Weibull distribution with the
full probability range (of the likely point of the onset ofjnealth effects
for the 99th percentile individual) provided by its panel to obtain a second
set of probabilities of health effects being experienced, at alternative ozone
il/
standards.
Finally, EPA has concluded that a standard of 0.10 ppm provides a satis-
factorily low risk of health effects being experienced.
In summarizing EPA's approach, we aight characterize it as a "critical
point, critical person" methodology: From the continuum of effects, EPA has
43 FR 269.67.
_ 43 FR 26966.
ll/ 43 FR 269.67. In its Risk Assessment document, EPA also provides risk
ribbons that demonstrate the full range of uncertainty concerning the
experiencing of health effects. See ''A Method for Assessing...." op. cit.,
pp. 2-29 to 4-39.
-------
- 6 -
chosen a particular point and characterized it as representing the onset of
health effects; from the range of individual continuums, it has chosen the
99th percentile individual (among the sensitive group). aad tried to locate
the ozone level at which this individual first experiences health effects.
(Even with EPA1 s alternative approach or concluding that 0.15 ppm is the level
"at which health effects are virtually certain," these effects are clearly
experienced only by individuals at the most sensitive end of the spectrum and
not by less sensitive individuals.1 Then, incorporating the full uncertainties
of the location of this critical point (for this critical individual) and the
uncertainties of meteorology, EPA has set a standard that it views as offering
a satisfactorily low risk.
The Review Group has three major criticisms of the approach. First, and
most fundamentally, this "critical point, critical person" methodology ignores
the question of aggregate exposure to unhealthy ozone concentration levels. By
focusing on the risks that a particular point for a particular individual (or
class of individuals) will be exceeded, EPA's approach ignores the full--
continuum of effects and the complete range of continuums across individuals of
differing sensitivities. Second, the "critical point, critical person"
methodology requires a number of steps or decisions, for which there are no
adequate rationales or methodologies (e.g., why did EPA choose the 99th percentile
individual as the critical person? How did EPA decide what was a suitably low
risk?). Third, EPA's assessment of the existing literature and its panel selection
procedures deserve comment.
The following discussion expands on these points.
1. Ignoring Aggregate Effects
3y focusing on "those persons "who are more" sensitive'than" 99~percent
of the sensitive group but less sensitive than 1 percent of that group," EPA
-------
- 7 -
has effectively ignored the full range of sensitivities among individuals.
In particular, the remaining 1% of the sensitive population will likely
experience health effects at lower ozone concentration chan does the "critical
127
person," possibly all the way down to zero. Thus, focusing on the risks
of the "critical person" experiencing health effects totally neglects the
greater risks (or, indeed, virtual certainty) that yet more sensitive
individuals will experience health effects. Also, there are slightly less
sensitive individuals than the "critical person" who also run risks of
experiencing health effects (albeit lower risks than the "critical person").
Again, the focus on the "critical person" ignores these other risks.
Further, EPA's approach ignores the continuum of effects. The "critical
individual" is likely to experience yet more severe health effects at ozone
concentrations that are higher than the "critical point;" these higher con-
centrations have a small but finite possibility of occurring. Yet, these more
severe consequences do not enter into EPA's calculus of decision. Similarly,
the more sensitive 17, are likely to experience more severe health effects at
the same ozone level that just induces the "critical point" health effects in
the "critical person." Again, these more severe effects are ignored. And,
equally, the effects just below the "critical point" are ignored for all
individuals.
Another way that the "critical point, critical person" methodology ignores
aggregate effects is through E?A's neglect of the considerable variation in
ozone concentration levels across geographic areas within an Air Quality Control
Region (AfjCR) . EPA's proposal appears to assume that any observed exceedance
of the standard will be experienced equally by all people living in the AOCS..
12/ EPA's Risk Assessment document acknowledges this point. Ibid, pp. 2-25
to 2-27.
-------
- 8 -
la face, however, ozone concentration levels vary substantially across an
13/
AQCR at any one point in time. For example, in 1975 there were nine
monitors measuring ozone concentration levels in the Denver AOCR. These
monitors reported, respectively, the following numbers of days in which
average one-hour ozone concentration levels exceeded 0.10 ppm for at least a
14/
single one-hour period: 24, 21, 19, 10, 2, 2, 0, 0, 0. If only the
highest of these readings (24 exceedances) is used, Denver's population of
1,228,000 would appear to be exposed a total of 29,427,000 person-days to ozone
concentration levels in excess of 0.10 ppm. In fact, people living in the
areas adjacent to the last three monitors experienced no concentrations of ozone
above 0.10 ppm, even though there were exceedances in other areas. Thus, when
the geographical variation in exceedances and the population densities in che
Denver area are taken into account, the actual exposure was only half as
!£/
large — 14,700,000 person-days. Further data directly showing the variation
across a number of monitors in the AOCRs of the Northeast are provided in
Appendix A.
13/ See Committee on Medical and Biological Effects of Environmental Pollutants,
Division of Medical Sciences, Assembly of Life Sciences, National Research
Council, National Academy of Sciences, Ozone and other Photochemical
Oxidants, 1977, pp. 130-163; and U.S. Council on Environmental Quality,
Environmental Quality-1977. December 1977, pp. 153-159.
14/ This data has been provided by Dr. Kay Jones of CEO.
15/ Even this figure slightly over-estimates the likely exposure, since the
population figures are based on residential location. Peak ozone
concentration levels tend to occur in the afternoon, when many people
are at work in the central city, where peak ozone concentration levels
tend to be lower. CZQ figures indicate roughly the sane 50% reduction in
person-days of exposure for six other cities that have been studied:
Portland, Oregon; St. Louis; Boston; Louisville, Philadelphia; and
Washington, D.C. And an EPA study shows a similar 5QZ factor for
exceedances for 0.08 ppm in the Los Angeles AOCR. See Y, liorie, A. S. Chaplin,
and E. D. Helfenbein, Population Exposure to Oxidants and Nitrogen Dioxide
in Los Angeles, Volume II: Weekday/Weekend and Population Mobility Effects,
Office of Air Waste Management, Office of Air Quality Planning and Standards,
U.S. EPA, January 1977, pp. 20-36.
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- 9 -
Exposure variability has clear implications. Since populations are
dispersed across AQCIls and ozone concentrations reach peaks in some areas
(which are monitored for compliance with the standard) but are lower in other
areas, then any standard set to achieve a certain level of health protection
can be set more leniently and still achieve the desired level of protection.
16/
Further, ozone levels tend to be lower indoors than outdoors. The
NAS has suggested that indoor peak concentrations may reach only 70% of the
W
level of outdoor peaks. Many people, therefore, experience appreciably lower
ozone concentration levels than those registered by outdoor monitors. Again,
this means that a more lenient standard can be set that will nevertheless
17a/
achieve the desired level of health protection.
In sum, the "cirtical point, critical person" methodology does not provide
the complete picture of the consequences of ozone exposure. In Section C, we
will propose an alternative methodology that has the potential for providing
this complete picture.
2. The Absence of a Rationale for the Crucial Steps in the "Cricital Point,
Cricital Person" Approach
Development of the ozone standard on the basis of the "critical point,
critical person" approach requires three crucial judgmental decisions: (1). What
is the critical point in the continuum of effects at which a health effect is
considered to be present? (2) Which individuals, in the range of sensitivities
167 NAS, op. cit., pp. 163-165; CEQ, op. cit., 167.
JL77 NAS, op. cit., p. 164.
17a/ Note that we are not suggesting that people should be required to go indoors
(or leave the area) during a period of high ozone concentrations. Rather,
we believe that an ozone standard should be set_so. as to_achieve, an
intended level of protection. If the standard is set on the assumption that
all people are outdoors during the period of peak concentration, whereas
actually some people are normally indoors Cor living in a lower ozone
neighborhood) at that time, the standard is over-protective; a more lenient
standard would achieve the intended level of protection.
-------
- 10 -
across Che entire population, will be chosen as the critical individual, for whom
the critical point must be determined? (3) What level of risk (that this
critical individual will experience health effects) is tolerable?
The first decision is one on which scientific opinion must be relied,
although, again, this focus on the critical point ignores the effects on
both sides of it. The latter two decisions, however, clearly involve policy
choices rather than scientific decisions. Yet, EPA has not offered an
adequate rationale or methodology to show how it arrived at its choices. How
was the scope of the sensitive group, from which the 9.9.th percentile individual
was selected, determined? Should it be asthmatics, asthmatics plus anyone
18/
exercising vigorously, or asthmatics, exercisers, plus the young and the elderly?
Further, and equally importantly, why has EPA chosen the 59th percentile individual?
18a/
Why not the 95th percentile? Or the 90th percentile? Since the sensitive
group itself is only a small fraction of the population (e.g., asthmatics and
others with breathing difficulties are 3-5% of the population), the choice of
the 95th or 90th percentile individual would still have implied only a
comparatively small number of yet more sensitive people who would receive less
protection.
Similarly, the determination of the level of acceptable risk of health
effects for the critical individual has no adequate rationale. Why is a 0.52
probability of a health effect being experienced at the Q.10 ppm standard acceptable,
18/ Apparently, various members of the expert panel had differing views as
to the categories to be included in this sensitive group. "A Method for
Assessing....," op. cit., p. 4-5. This raises the possibility that each
of the experts was characterizing a different individual as '"the"
99th percentile person.
18a/ EPA has considered these alternatives, and did ask the expert panel for the
probabilities concerning the 9Jth and 90th percentile individuals. See "A
Method for Assessing..," pp. 2-25 to 2-27, 4-30, 4-31, and 4-34. But in the
end thev have not offered an adequate rationale for their choice.
-------
- 11 -
197
whereas a 0.67 probability at a Q.12 ppm standard unacceptable? EPA's
statement that "the choice of a standard between zero and a level at which
2_0/
health effects are virtually certain (0.15 ppm) is necessarily subjective"
is simply not sufficient. In Section E, we will suggest an approach that
removes a good deal of the subjectivity from this choice.
3. Assessment of Existing Literature and Panel Selection
With respect to the currently available evidence, EPA appears to rely
21/
heavily on the De Lucia and Adams study for concluding that 0.15 ppm of
ozone is the concentration level at which "health effects are virtually
22/
certain." Unfortunately, the De Lucia and Adams study simply will not
support such a conclusion, as EPA's criteria document indicates:
De Lucia and Adams studied the effects of graded exercise on
lung function and blood biochemistry in six men after one hour
of exposure to 290 yg/m3 (0.15 ppm) and 590 yg/m3 (0.30 of
ozone via a mouthpiece. The workloads were 25 percent, 45 per-
cent, and 65 percent of each individual's maximum oxygen
uptake (VQ- max.). Ventilation volume and V^ were unaffected
by even the most severe exposure/excessive protocals. However,
most subjects demonstrated signs of toxicity (symptoms such as
congestion, wheezing, and headache) during the most stressful
protocols. In addition, vital capacity, forces expiratory
after volume at 1 second, and midmaximum flow rate decreased
significantly after inhalation for 1 hour of 59JD ,^g/m2 CO.30 ppm)
at 65 percent VQ2 max. Discernible though not statistically
significant changes in resniratory pattern were also observed
after exposure to 290 yz/ia? (0.15 ppm) ozone and exercise ac
65 percent VQ2 max.?-P/ [Emphasis added.]
Further, it is worth emphasizing that the De Lucia and Adams study involved
tests on only six individuals.
I?/43 FR 26967.
2_0/ 43 FR 26967.
21/ A. J. De Lucia and W. C. Adams, "Effects on 0, Inhalation During Exercise
or Pulmonary Function and Blood Biochemistry, J. Appl. Physio.: Respirat.
Environ. Exercise Physiol. 43(1): 75-S1, 19.77.
22_/ 43 JR 26967.
23/ Office of Research and Development, U.S. EPA, Air Quality Criteria far
Ozone and Other Photochemical Oxidants, Volinre II (April ISJSi, Ch. 9_, p. 13,
-------
- 12 -
Virtually all of Che remaining clinical studies cited in the criteria
document describe health effects found at ozone concentrations of 0.25 ppm
25_/
or above. The main exception is a German study by Von Nieding et. al. which
describes some effects at 0.10 ppm, but substantial methodological questions
W
have been raised about this study. Similarly, the epidemiological studies
cited in the criteria document mostly focus on health effects found at levels
_27/
of 0.25 ppra or above, though Wayne et. al. found effects on athletic
28'
performance at lower levels and Japanese studies have found effects at
low ozone concentrations. Again, there may be serious methodological problems
_29/
with these latter studies. It should also be stressed that a number of
studies have failed to find statistically significant effects in the range
30/
of 0.25 - 0.37 ppm.
A balanced summary of the evidence would appear to supper* the following:
!£/ Ibid, Ch. 9.
25/ A Von Nieding, H. M. Wagner, H. Loellgen, and H. Krekeler, paper presented
at the VDI Kommission Reinhaltung der Luft Colloquium on Ozone and Related
Substances in Photochemical Smog, Duesseldorf, West Gernany, 1976.
26/ Among these, other pollutants nay not have been adequately removed, and
the measurement procedures appear to have been different from those usually
used in the U.S. See Phyllis'J. Mullenix, ''Health Effects of Photochemical
Oxidants," submitted to the American Petroleum Institute, February 15. 1978.
27/ W. S. Wayne, ?. P. Wehrle, and R. E. Carroll, "Pollution and Athletic
Performance," J. Amer. Med. Assoc. 1990.2).: 901-9.04, March 20, 1967.
28/ There is a serious methodological question as to whether the relationship
that Wayne et. al. found is linear between ozone and performance or has a
threshold at 0.12 ppm. See Alan Gittelsohn, "Evaluation of Hocky Stick
Functions Used to Establish Pollution Health Effect Thresholds," submitted
to the American Petroleum Institute, June 29, 1977. Also, Wayne et. al.
related relative athletic performance (this week versus last week) to ozone
concentrations this week. The proper comparison should have been with
the relative ozone concentrations (this week versus last week).
29/ Some of the symptons observed may have been induced by the subjects'
knowledge of prevailing ozone levels. A3 FR 26966.
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- 13 -
Health effects appear to have been demonstrated with a high
degree of certainty in the range of ozone concentration above
0.37 ppo. In Che range of 0.25 - 0.37, effects are less certain,
with the least certainty at the lower end of this range. The
evidence for human health effects below 0.25 ppra is quite sparse,
and the evidence of significant adverse effects below this level
317
is even weaker. Put another way, the evidence does not appear
to support the claim that significant human health effects have
been "clearly demonstrated" or are "virtually certain" at 0.15 ppra
or even at 0.20 ppm.
Further, it is important to note that all of the ozone-related health
effects that have thus far been measured appear to be short-term and reversible.
Thus, although the affected persons may experience discomfort during exposure
to high ozone concentrations, individuals regain their previous state of
health shortly afterward. Thus far, ozone exposure has not been demonstrated to
have long-term debilitating consequences in hunians.
In addition to surveying the currently available evidence, as noted
above, EPA has asked a panel of experts to provide their judgments as to the
probability that various ozone concentration levels would cause health effects
327
in the critical person. Though the panel consisted of nine experts, only
three offered their judgments on any particular health effect category. This
31/ Animal studies have demonstrated decreased resistance to infection and
long-term non-reversible effects from relatively low ozone concentrations.
See "Summary Statement from the EPA Advisory Panel ," op. cit., ?p. 12-16
and Air Quality Criteria:..., op. cit, Volume I, Ch. 8. These effects
have not vet been demonstrated in hunans, however, and the epidemiological
studies have yet to produce any evidence of long-term effects in humans.
I2j Strategies and Air Standards Division, Office of Air Quality Planning
and Standards, U.S. EPA, "A Method for Assessing the Health Risks
Associated with Alternative Air Quality Standards for Ozone," July 19.78.
-------
is an extremely small sample and raises Che possibility of a very large
potential variance in the conclusions of the panel. Ideally, the
panel would accurately reflect the views of the experts in the field (and
the degree to rfhich there is or is not a consensus of opinion). Other
things being equal, the larger the panel, the smaller the potential variance
in the representation of the views of the entire population of experts. We
recognize that the costs of larger panels are not trivial, but the cost
differences among alternative ozone standards are quite large (see Sections 3
and C) ; more accurate information has sizable consequences. We urge EPA to
consider the use of larger panels for these risk assessment studies.
It is worth reviewing the major conclusions of this seccion. EPA has
pursued a "critical point, critical person" methodology. In so doing it has not
taken into account the full continuum of effects and the full range of
sensitivities among the population. Questions of geographic variability
of ozone concentrations within an AOCR and indoor-outdoor differences have not
been addressed. It has thus not focused on nor provided a measure of total
unhealthy exposure or total effects. Further, EPA has not justified its
crucial policy choices within the "critical point, critical person" framework.
And EPA appears to have inappropriately interpreted the existing literature
concerning ozone.
Even if one were to accept the general aethodology that EPA has used, a
less stringent standard would appear to achieve the goal of protecting the
public health. The inclusion of geographic variability and indoor-outdoor
differences alone would probably allow the standard to be .raised-to-0.12-opm-
-------
- 15 -
and still achieve the same consequences as EPA believes it is achieving
33/
with its 0.10 ppra standard. Alternatively if EPA decided to focus
on the 95th percentile or the 90th percentile of the most sensitive group
(again, we are still considering a small fraction of the population),
34/
standards of 0.12 ppm or 0.14 ppm, respectively, would be adequate.
As yet another alternative, if EPA concluded that the currently available
evidence points to 0.25 ppm as the proper critical point, a standard of
0.16 ppm would be adequate. We urge EPA to reconsider its "critical
point, critical person" methodology and to consider adopting an alternative
methodology which would focus on total effects. But if EPA persists with its
current methodology, we strongly urge it to reconsider these proximate
decisions at each stage and thus reconsider its overall standard.
337 This would be true if, say, when the reading at the high monitor was 0.18 ppm,
the average exposure — because of the geographic variability and because
of the 70% indoor reduction in exposure — was 0.15.
34/ These consequences are derived from examinations of the "risk ribbons" on
pp. 4-29, 4-30, and 4-31 of "A Method for Assessing " op. cit.
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- 16 -
B. Determining the Costs of Compliance
EPA has estimated the likely coses involved in achieving compliance with
357
alternative ozone standards. These cost estimates provide a useful backdrop
for understanding one important set of consequences of the alternative standards.
Also, as noted in Section D, these cost estimates are an important component
of the balancing that is necessary for the determination of the secondary standard.
The cost estimates are derived in the following manner for each of the
90 AQCRs: A background concentration level of ozone is assumed. Likely growth
in hydrocarbon emissions from various sources is projected. Two alternative
models, rollback and EKMA (Environmental Kinetic Modeling Approach), are used
to estimate the reductions in hydrocarbon emissions that would be necessary
to achieve the alternative ozone standards. Where possible, present and likely
future emissions reductions possibilities are identified and costed. Finally,
any remaining hydrocarbon reductions necessary to achieve the standard are
assumed to take place, through unspecified means, at a cost of $1,000-$1,300
per ton.
We believe that the estimated costs of meeting the alternative standards
have been substantially understated for a number of cost categories.
1. The Federal Motor Vehicle Control Program (FMVCP)
The EPA considers the costs of the FMVCP to be a fixed cost, which will
be incurred at all likely ozone standards. This may be an inappropriate
assumption, since one of the major justifications that has been advanced for
the stringent control standards of the FMVCP is that they are necessary to
35/ Economic Analysis Branch, Strategic and Air Standards Division, Office
of Air Quality Planning and Standards, U.S. EPA, "Cost and Economic
Impact Assessment for Alternative Levels of Che National Ambient Air
Quality Standard for Ozone," June 1978.
-------
- 17 -
36/
allow AQCRs to come into compliance with the stringent ambient ozone standard.
Nevertheless, we shall follow EPA and assume that these costs are fixed. Thus,
they do not affect the marginal cost calculations reported in Table 1.
EPA reports that control of hydrocarbons (HC) and carbon monoxide (CO) for
light duty vehicles will involve "an installed cost of approximately $218 per
377 37a/
vehicle." This figure is far too low. It includes only the cost of the
hardware installed on the car and totally neglects the extra fuel, maintenance,
and inconvenience costs of the control technology.
The proper costs may be calculated as follows: For 1981 and after,
automobiles will have to meet emission standards of 0.41 grams/mile for HC and
3.4 grams/mile for CO (and 1.0 grams/mile for N"0X). In 1974, the National
Academy of Sciences - National Academy of Engineering study estimated that a
car meeting the standards of HC=0.41 grams/mile, C0=3.4 grams/mile, and NOX=2.0
3&/
grams/mile would have a discounted lifetime cost of $361 over a 1970 car.
These costs include initial hardware, extra maintenance, and extra fuel. An
additional cost of $30 should be added for pre-1970 controls on HC and CO.
Part of these costs are due to the NOX controls. But since the 2.0 grams/taile
NOX standard is not very severe, perhaps S&O of this cost should be subtracted
36/ See Air Quality, Noise, and Health, Report of a Panel of the Interagency
Task Force on Motor Vehicle Goals Beyond 1980, Department of Transportation,
March 1976, pp. 5-55.
37/ "Cost and Economic Impact....," op. cit., p. 4-2.
37a/ EPA has subsequently acknowledged that its $218 figure is coo low and
believes that it is higher, though not as high as the $441 figure
mentioned below.
38/ Coordinating Committee on Air Quality Studies, National Academy of
Engineering, Air Quality and Automobile Emission Control. Volume IV,
prepared for the U.S. Senate, Committee on Public Works, September 1974,
p. 64.
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- 18 -
to account for the NO,, standards. This leaves S331 as the lifetime cost of the
39/
HC and CO controls, as of 1974, or $441 in 1978. Thus, EPA has understated
the annual FMVC? costs by 50%. EPA states that these annual costs are likely Co
be S2.8 to $3.0 billion. la fact they are likely to be $5.6 to $6.0 billion.
2. The Inspection and Maintenance Program for Automobiles
EPA estimates that the net cost of mandatory inspection and maintenance (I&M)
programs for automobile emission controls will only be $5 per car, because main-
tenance costs of $26-536 per car serviced will be offset by gasoline savings of
40/
roughly the saiae magnitude. A^ain, this cost figure is too low, because the
repair costs appear to be too low and the likely gasoline savings from the
required maintenance appear to be very small.
EPA has conducted a series of evaluations of restorative maintenance of
vehicles co meet the 1975 standards, in Detroit, Chicago, Washington, D. C.,
41/
and San Francisco. Among other things, these studies estiaiated the costs of
the required maintenance and measured fuel economy before and after maintenance.
For the first three cities, the average inspection and maintenance costs for 300
cars was §41.44 per car, including those that did and did not require maintenance.
Thus, EPA's S26-$36 per car should probably apply as an average to all cars
39/ Between May 1974 and May 1978, the Consumer Price Index for new cars
increased by 33.1%.
40/ "Cost and Economic Impact " op. cit., pp. C-8 to C-9.
41 / See R. Gafford and R. Carlson, Evaluation of Restorative Maintenance on
L975 and 1976 Light-Dutv Vehicles in Detroit. Michigan (May 19//;;
n R r-Mj^hi 2nd T. Terrv. Evaluation of Restorative Maintenance on
1975 and 1976 Light-Duty Vehicles in Chicago. Illinois U*nuary 1977 ;
L. H. Washington? Evaluation of Restorative Maintenance on 1975 and 1976
Light-Dutv Vehicles in Washington. D.C. (March L977) and Automotive
,:„..,•>. a^i g»erome, Tnr.. EvalTHtToTT of Restorative Maintenance on 1975
and 1976 Light-Dutv Vehicle in San Francisco. California (October 19" >•
All four are oublished by Emission Control Technology Division, Of.ice or
Mobile Source" Air Pollution Control, Office of Air and Waste Management,
U.S. EPA.
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- 19 -
41a/ •
noc just to those serviced. Further, the average fuel economy improvement
42/
for the 300 cars was only 1.5£. For San Francisco, where maintenance had to
43/
resore the cars to a tighter standard, fuel economy actually fell slightly.
Even a 1.52 fuel economy improvement does not save much money. In 1987, if average
fleet mileage is 25 MPG, if cars in AQCRs travel an average of 12,000 miles per
year, and if gasoline costs 70c per gallon (in 19-73 dollarsJ, average annual
gasoline costs per car will be $336. A 1.5% fuel economy improvement would only
yield annual savings of $5.04 per car.
Thus, the net costs of inspection and maintenance are likely to be around $25
per car or five times the figure that EPA has provided. If there are 70 million
' 44/
cars ia the 90 AOCRs, the total annual costs will be $1.75 billion. By contrast,
45/
EPA estimates the total annual costs at only $350 million - $450 million.
Also these I&M cost estimates ignore the likelihood that I&M programs will
be imposed state-wide in most states, not just in AOCRs. Thus,, the actual costs of
the I&M program are likely to be yet 50% higher than the $1.75 billion figure.
(Nevertheless, we shall use the $1.75 billion in cost adjustments below and in
Section C.)
41a/ It is not clear how much of the costs (JLa the evaluation studies) are devoted
to inspection that would not need to occur under more realistic circumstances.
Also, it is not clear if costs of these magnitudes would continue to apply
if I&M were on an annual basis. Offsetting this is the fact that the study
only considered relatively new cars; restorative maintenance on older cars Bay
be more extensive and more costly. And the 1987 standard will be considerably
more stringent than the 1975 standards. Maintenance costs cer car in San
Francisco, where the more stringent California standards were the target, were
25% above those for the other three cities.
42/ J. C. Bernard and J. F. Pratt, An Evaluation of Restorative Maintenance
on Exhaust Emissions of. 1975-1976 Model Year In-Use Automobiles, Emission
Control Technology Division, Office of Mobile Source Air Pollution Control,
Office of Air and Waste Management, U.S. EPA, December 1977, p. B-18.
43/ Automotive Environmental Systems, op. cit., p. 24.
44 / If fewer AQCRs require I&M at more lenient standards, the cost would
obviously be less.
— 7
pp
nhff6 fi8-f ".,*?? gained b^ *ulci?lyinS S530/ton of hydrocarbons times
0.66 - 0./6 million tons. See "Cost and Economic Impact.... " on c*c
p- 3-15 and 4-6. " '
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- 20 -
As a final methodological 'note, we should point out that even if the EPA
were right in assuming that gasoline cost savings would offset inspection costs,
the real costs of the I&M program must nevertheless be higher, because of the
inconvenience costs involved (which have not been included but would raise our
estimates even higher). If maintenance actually paid for itself, motorists
would do it voluntarily, and there would be no need for mandatory inspections!
Since this is not the case, Che inconvenience costs involved in both the
inspection and the maintenance must clearly be non-trivial.
3. Emission Controls for Heavy-Duty Vehicles and Motorcycles
The Clean Air Act includes heavy duty vehicles (trucks and buses) and
motorcycles, as well as automobiles, in its emission control requirements.
There currently are interim control requirements on these vehicles (controlling
perhaps 50% of emissions on heavy duty vehicles and 35/2 on motorcycles), and
the Act mandates reductions in HC and CO by 1983 for these vehicles that are
46/
as stringent as the requirements for automobiles. Indefinite delays in the
enforcement of these requirements are permitted, so enforcement is far from certain.
EPA has completely excluded the costs of these controls from its estimate
of the costs of the FMVCP program. These costs should properly be included,
though they should also be considered a fixed cost that will be present for all
alternative standards.
Specifically, if the 1983 requirements are put into force, the emission
control costs per new heavy-duty vehicle should be at least as great as they
are for automobiles. As we saw, the new car costs of the FMVCP were likely
to be S5.6-S6.0 billion per year. Sales of new heavy duty vehicles have
averaged 30% of the sales of automobiles, so che annual costs of the FMVCP
program for heavy-duty vehicles should be at least SI.7-31.8 billion.
The costs of motorcycle controls are acre difficult to calculate.
Current controls are being met at very modest costs, but the 1983 controls
46/ Clean Air Act as Amended, August 1977, Sec. 202(a)(3)(A)(ii)(I).
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- 21 -
promise greater problems. Yet, the control costs per new motorcycle could not
equal that for new cars, since costs of this magnitude would bulk too large
compared to the price of a new motorcycle. If we take a quarter of the new
car control costs as a. conservative estimate of new motorcycle control costs,
and we take motorcycle rates at 5% of new car sales, we add another $75 million
to the costs of the FMVCP program.
The only costs that EPA does recognize with respect to reducing emissions
from heavy duty vehicles and motorcycles are those from some modest transportation
controls. The estimated annual cost is $30 million, composed of $l,000/ton
'±U
times 0.03 million tons reduction.
In addition, it seems quite likely that I&M, comparable to that required
for automobiles, will occur. The truck fleet will average 302 of the size of
the automobile fleet; the motorcycle fleet will average 5%. If, as we estimated
above, the automobile I&M annual costs are likely to cost SI.75 billion, the
truck and motorcycle I&M annual costs are likely to be S610 million. And,
again, if truck and motorcycle I&M are required state-wide rather than just in
AOCRs, the costs would increase by another 50%.
The I&M for these vehicles would reduce HC emissions by roughly 0.22
48/
million tons. This reduces the emission control requirements from other sources
by the same amount, so 0.22 million tons will be subtracted from the fieuras below.
4. Other Costs
We have not tried to calculate alternative cost estimates for other
categories of emission controls. We are, however, uneasy concerning the "they
47/ Ibid., pp. 3-15 and £-6.
&8 / EPA estimates automobile I&M will reduce automotive emissions by 37"; we
have used the same assumptions to arrive at Q.22 million tons. Ibid., p. 3-15,
-------
- 22 -
pay for themselves in recovered materials, therefore they are costless"
arguments that appear in a few places, especially in the discussion of
petroleum refining.
There is one residual category of costs, however, that is particularly
troublesome. This is the "additional reduction required" category, which is
simply the residual reduction required after all identified reductions have been
accounted for. EPA uses alternative cost estimates of Sl,000-$l,500 per ton
49/
for the residual category, which EPA admits is a "lower-bounds estimate."
This figure is far too low. The I&M programs at their true costs
50/
calculated above, cost roughly S2,50Q/ton. It is unlikely that the
unidentified, residual reductions will be any easier or cost any less. If
we use this 52,5007ton figure instead, the costs of the 0.10 ?pm standard
increase by Sl.O billion (using rollback) or $2.9 billion (using EXMA), with
5I7
smaller cost increases at less stringent standards.
It is worth noting how just the higher costs identified here — the
higher motor vehicle costs and the higher residual costs — increase EPA's cost
estimates. EPA estimates the costs of meeting the O.LO ppm standard at S6.9
billion (rollback) to §9.5 billion (EKMA). The higher costs identified here
raise these figures to $14.3 billion (rollback) and $L8.8 billion (EXMA). Thus,
the likely costs of meeting the 0.10 ppm standard appear to be at least twice
as large as EPA's estimates.
49/ Ibid., p. 4-14.
5Q/ The automobile I&M will cost SI.75 billion and remove 0.66-0.76 million
tons of HC.
51/ The residual costs here incorporate what the EPA considers "advanced"
reasonably available technology, but the 0.2 million tons removed by
truck and motorcycle I&M have been subtracted.
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- 23 -
C. An Alternative Approach
It is worth recounting the important aspects of the ozone problem: there
is a continuum of effects; there is a range of continuums, stretching from the
most to the least sensitive person; the location of the continuum for any class
of seasons is uncertain; and ozone concentration over time are best described
by a probability distribution. A proper approach, then, should incorporate
all of these aspects. The dose-response patterns for given individuals (at
successively higher ozone concentrations, what effects does a given individual
experience?) and across the population (e.g., at what ozone concentration level
does the most sensitive 0.01% of the population feel a given effect? The most
sensitive O.l%? The most sensitive 1%, etc.) should be estimated. With these
dose-response relationships (including any uncertainty surrounding them) and a
probability model for temporal and geographical occurrences of ozone concentra-
tion levels, one could estimate and then compare the expected annual person-hours
of exposure to ozone that are likely to generate effects, using dif^e^en'-
52/
proposed ambient standards. The choice among alternative standards, then,
would have to be based on how many person-hours of unhealthy exposure are
considered tolerable.
Unlike EPA's "critical point, critical person" approach, this alternative
approach would make explicit use of all of the aspects of the ozone problem
that EPA agrees are likely to be true, and it would develop directly the
quantitative measures of likely unhealthy exposure at any alternative standard.
A more explicit statement of the consequences of alternative standards should
help in the development of public policy.
52/ It is worth noting that this approach is quite consistent with that
suggested by the NAS Ozone Study, op. cit., p. 130.
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- 24 -
53/
In Table 1, we offer an example of the application of this methodology
Appendix B contains the detailed description of the specific formulation used
here. We should stress that the specific numbers are meant to be suggestive
rather than our definitive statement of what we think the numbers exactly to be.
We do believe, however, that the general form of the outcome of this example
has general validity for the ozone problem and that the general magnitudes are
correct.
In Table L, Column (1) shows the assumed standard. Column (2) shows the
expected annual number of person-hours of unhealthy exposure, as explained
above and in Appendix B. Column (3) shows the difference in person-hours of
health effects as one goes from one standard to the next more stringent standard.
As one would expect, the Table indicates that as the standard is tightened,
the expected annual number of person-hours of unhealthy exposure to ozone
decreases (but not to zero at any standard short of zero!). But over this
range or feasible standards, the Tnarginal reduction in person-hours of
unhealthy exposure decreases as the standard becomes tighter.
There is no obvious cut-off point for establishing the standard. There
is no absolute level of safety. At all standards there will be health effects.
EPA's choice among these alternative standards, using these kinds of outcomes,
will not be an easy one. But this kind of methodological framework helps to
make the consequences of the choice more explicit.
We can also incorporate the estimated costs of meeting the alternative
standards, discussed in Section B, into the analysis. In Table 1, EPA's
53/ In the absence of readily available dose-response curves for given
individuals and of a readily available weighting scheme for different doses
of ozone for an individual, we have, for the purposes of this example, used
only the critical point, the onset of a health effect, as explained in
Appendix 3.
-------
(1)
Standard
0.08 pI>m
0.10
0.12
O.l/i
0. 16
0.1H
0.20
(2)
Expected
Person-
1 lours of
llnlieal Lliy
Exposure
Ln Ozone
8.JS7.201
8,827,200
9,746.584
10,977,856
12,623,848
14,882,704
18,082,608
(3)
Difference
in Expected
Person-Hours
639,999
919,389
1,231,272
1,645,992
2,258,856
3,199,904
(4) (5)
Estimated
Coses of
Meeting
Standard,
Rollback Difference
HodelH/ Jn Costs
$8.5 bll.
$1.7 bil.
$6.9
$1.0
$5.9
$0.7
$5.2
$0.4
$4.8
$0.2
$4.6
$0.2
$4.4
(bj
Extra
Cost per
Reduced
Person-
Hour of
Unhealthy
Kxpoaure
$2,660
$1,090
$570
$240
$90
$60
(7)
Estimated
Cost of
Meeting
Standard. EKMA
Model a/
$12.1 bll.
$9.5
$7.5
$6.7
$6.0
$5.6
$5.3
(9)
(8) Extra
Cost per
Reduced
Person-
Hour of
Difference Unhealthy
in Costs Exposure
$3.6 bll. $5,630
$2.0 $2,l'bO
$1.8 $1,460
$0.7 $430
$0.4 $180
$0.3 $90
a/ Costs are ihe sum of the costs of the Federal Motor Vehicle Control Program, new source control, reasonably
"~ dvulldhlu control technology, and $l,500/tou la reduce any remaining emissions necessary to meet the
alternative standards. These arc annual costs, »a of 1987, Jn 1978 dollars.
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- 25 -
original (unadjusted) cost estimates are used. Since the cost estimates vary,
depending on whether a roll-back model or an EKMA model is used to estimate the
needed hydrocarbon reductions, both cost estimates are provided in Columns (4)
Ii'
and (7). The extra costs of meeting the next more stringent standard are
provided in Columns (5) and (8). And the extra cost per reduced person-hour of
health effects is provided in Columns (6) and (9).
Again, as one would expect, the costs of meeting the ozone standard
become higher as the standard becomes more stringent. And the marginal costs
of meeting the more stringent standards become progressively higher. Finally,
the marginal costs per reduced person-hours of unhealthy exposure climb rapidly
at more stringent standards, both because the marginal costs are rising and
because the reduction in the number of person-hours of unhealthy exposure falls
off. If we use the roll-back model, the marginal cost of a reduction of one
hour of unhealthy exposure to ozone is roughly SHOO when we go from a 0.12 ppm
standard to a 0.10 ppm standard; for the EKMA model, the marginal cost per
person-hour is roughly 52,200 for the same change. 3y contrast, when we go
from a 0.18 ppm standard to a 0.16 standard, the rollback model indicates a
marginal cost per person-hour of only $90, whila the EKMA model indicates
S180 for the same change.
Table 2 contains similar cost calculations embodying the revised cost
estimates discussed in Section 3. We have added the new FMVCP costs (auto and
truck) as a fixed cost to all alternative standards. The maximum amount of
the new inspection and maintenance costs (auto and truck) and new residual costs
54/ The costs differ slightly from those provided in "Cost and Economic Impact...
op. cit. The cost levels here are the sum of the costs of the Federal Motor
Vehicle Control Program, new source control, identified reasonably available
control technology, and an assumed cost of $l,500/ton for reducing remaining
hydrocarbons necessary to meet the standards. These figures have been
provided by Deborah Taylor of the Office of Planning and Evaluation, U.S.
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- 25a -
<0
Table 2; Costs of Person-Hours of Exposure, Revised Costs
(4)
(5)
Estimated Costs of
(6)
fixtra Cose per
Reduced Person-
(7)
Estimated Cost
of Meeting
(8)
(9)
Extra Cost
per Reduced
Person-Hour
Standard
0.08
0.10
0.12
0.14
0.16
O.IH
0.20
Meeting Standard.
Rollback Model -
$17.4 bil.
$14.3
$12.4
$H.(>
$10.2
$9.7
$9.2
Difference
in Costs
$3.1 bil.
Si.y
$1.4
$0.8
$0.6
$0.5
Hour of Unhealthy
Exposure b'
$4840
?2070
$1140
$490
$270
$]60
Standard. EKMA
Model -'
$23.2 bil.
$18.8
§15.0
$11.4
$12.0
$11.0
$10.1
Difference
in Costs
$5.4 bil.
$3.8
$1.6
$1.4
$1.0
$0.9
of Unhealthy
Exposure J*/
$8440
$4130
$1300
$850
$440
$280
«/ Cost nitres Include those shown in Table 1, plus revised FMVCP, T&H, and residual costs. See text for details.
b/ Sue Table 1 for relevant exposure numbers. '
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- 26 -
has been added co the 0.08 ppm standard, with proportionately less added to the
more lenient standards, and no:hing added to the 0.20 ppm standard.
As can be seen, HPA's proposed 0.10 ppm standard is now calculated to
cost $1A.3-$18.8 billion. The marginal costs of going from a 0.12 ppm standard
eo a 0.10 ppm standard are $1.9-$3.8 billion, and the marginal costs per
person-hour of unhealthy exposure are now In the range of S2100-S41QO, By
contrast, in going from a O.L8 ppm standard to a 0.16 ppm standard the marginal
costs per person-hour of unhealthy exposure are only $270-3440.
It is worth emphasizing again that the health effects that we have been
describing as occurring as a consequence of ozone exposure are largely those
of discomfort; the effects are reversible, and there is at present no evidence
of long-term debilitating effects from exposure co ozone at the concentration
levels we are considering.
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- 27 -
D. Setting the Secondary Standard
The secondary standard is supposed to be set at a level that will "protect
!!/
the public welfare." The Clean Air Act later indicates that
"All language referring to effects on welfare includes,
but is not limited to, effects on soils, water, crops,
vegetation, man-made materials, animals, wildlife, weather,
visibility, and climate, damage to and deterioration of
property, and hazards to transportation, as well as effects^
on economic values and on personal comfort and well-being. 56_/
^Emphasis added^_/
EPA has set the secondary standard for ozone at 0.08 ppm, apparently relying
EJ
entirely on evidence of possible damage to vegetation. There has been no
consideration of the "effects on economic values." As we saw in Tables 1 and 2,
the economic costs of the 0.0$ ppm standard are quite substantial. We urge
EPA to weigh these economic costs against the benefits of reduced damages from
58/
lower ozone concentration level before setting the secondary standard.
55/ Clean Air Act as Amended August 1977, Sec. 109, (b)(2).
567 Clean Air Act as Amended August 1977, Sec. 302,(h).
_57/ 43 FR 26963-26969.
587 See the Petition of American Petroleum Institute and Member Companies for
~ Review and Revision, in Re: Air Quality Criteria, National Ambient Air
Quality Standard and Control Program for Photochemical Oxidants, before
the Administrator, U.S. EPA, December 9, 1976, pp. 9-10.
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- 28 -
E. A New Methodology
la Section A we offered a critique of EPA's procedures in setting the
primary standard. We argued that EPA's "critical point, critical person"
methodology ignored the total effects of ozone exposure. Further, we argued
that crucial policy choices in applying the methodology had not been justified.
In Section C we offered an alternative methodology, based on person-hours of
unhealthy exposure. We believe that this alternative methodology deals with
ozone-related health problems in a superior fashion. Yet even that methodology
offers no explicit guidelines as to the specific cut-off point, the specific
standard that should be chosen, when all possible standards imply some
unhealthy exposure. In this section we will offer a new methodology which
addresses this last problem and which is still consistent with the goal of
"protecting the public health."
The fundamental problem in setting standards resides in the conflict
between Congress's apparent hope that there would be unique threshold
concentrationsbelow which the public health (of everyone) would be protected
and the likely reality that ao such thresholds exist. If there are no
thresholds, if there is a continuum of effects, if individuals vary substantially
in their sensitivity, then there is no way to protect the health of everyone.
There are no safety margins.
-------
- 29 -
The position that there are no thresholds for pollutants and other
dangerous substances is one toward which the scientific community has been
597
moving. The Report by the Committee on Interstate and Foreign Commerce,
House of Representatives, on the 1977 Amendments to the Clean Air Act appears
607
to have endorsed this position.
In the absence of thresholds, there will be some health effects felt
by some fraction of the population (albeit small) at any possible standard.
Any attempts by a government agency to find a "safe" level with a "safety
margin" must be misleading and is poorly conceived policy. Instead, any
effort to "protect the public health" must squarely accept the fact that no
safe level/and instead must decide on what degree of likely exposure constitutes
sensible public policy.
Let us now try to establish a few principles that are consistent with
this orientation. First, other things being equal, the more serious the
health consequences of exposure, the more worthwhile it is to restrict
exposure. Thus, sensible public policy should call for greater restriction
in the public's exposure to a serious pollutant, such as lead, than to a
less serious pollutant, such as ozone.
Second, in the case of two or more pollutants the health consequences
of which are roughly equal, restriction of exposure to each should be adjusted
to the point at which the marginal dollar of costs related to restriction
59/ See the summary of comments contained in the Report by the Committee
on Interstate and Foreign Commerce, House of Representatives, on the
Clean Air Act Amendments of 1977, Report Mo. 93-294, May 12, 1977,
pp. 110-112.
60/ Ibid., ??. 110-112.
-------
- 30 -
(e.g., controlling emissions), yields the same amount of protection (e.g.,
health effects avoided) for each pollutant. Any violation of this principle
would mean that the public health could be better protected (fewer health
consequences) at Che same total cost Co society by altering the expenditures
among pollutants until Che principle was satisfied.
Third, at equal degrees of restricted exposure, it is worthwhile for
society to spend larger sums per marginal reduction in health effects for
more serious pollutants and smaller sums per marginal reduction in health
effects for less serious pollutants. Again, any violation of this principle
would mean that the public health could be better protected fay altering
expenditures among pollutant categories.
The three principles enunciated thus far would escablishva proper
consistency across pollutant categories and ensure the best protection of
the public health for any total expenditure on controlling pollutants.
Acceptance and activation of these principles" by regulatory agencies would
be a large step forward in improving the regulatory process and better
protecting Che public health.
Fourth, regulatory efforts to restrict exposure to pollutants (once these
efforts have been made consistent across pollutants) should be consistent with
other efforts by the Federal Government to improve the public health and
safety, in terms of marginal costs per effect achieved. Again, the same
logic of best protecting the public health for any given amount of societal
spending applies.
-------
- 31 -
Finally, after this widespread consistency has been achieved, we are
still left with the problem of determining where the final line should be
drawn: how much should be spent on health, how much spending should government
regulation require from the private sector? Again, absolute safety, absolute
protection cannot be achieved short of zero levels of pollutants. But the
zero levels are impractical. As the House Committee on Interstate and Foreign
Commerce stated in its Report on the 1977 Clean Air Act Amendments, "...this
no-risk philosophy ignores all economic and social consequences and is
61/
impractical." And the regulatory agencies,by not setting standards at
zero pollutant levels, have implicitly-accepted this view.
Consequently, a line must be drawn. These lines are currently drawn ia
an implicit fashion by the regulatory agencies. Good policy requires that
they be made explicit and that they be consistent, as we have argued above.
Accordingly, regulatory efforts to restrict exposure to pollutants (and
other Federal health efforts) should be consistent with the preferences and
behavior of the general population with respect to health and with respect
co other goods and services in the economy. In the end, this will aean some
very difficult valuation nroblems. But in a world without thresholds and in
which a zero risk solution "ignores all economic and social consequences and
is impractical," these valuation problems cannot be avoided. Decisions to
"protect the public health" must necessarily focus on these valuation problems,
air then thoroughly, and try to reach correct and consistent judgments.
61/ Ibid., p. 127.
-------
Appendix A
i/
The tables in this appendix, taken from Cleveland, et. al. show
the hourly ozone concentration levels at a number of monitors in a few
AOCRs in the northeastern U.S. for a few days in 1974. The tables indicate
substantial variation in ozone concentrations across monitors within an
AQCR at any given time. They thus strongly support the argument in
Section A concerning geographic variability in ozone concentration.
These data (as do the other data and computations in the Celveland et. al.
paper) also point to a possible problem in enforcement and in determining
responsibility for non-compliance. The monitors are arranged on the page
from far northeast at the top to more southwest at the bottom. The prevailing
winds were blowing from the southwest (i.e., from the monitors at the bottom
of the page toward the monitors at the top of the page) . There is a clear
diagonal pattern of high ozone values, running from lower left to upper right
i.e., running from mid-morning upwind to mid- and late-afternoon downwind.
This implies that some downwind AOCRs (e.g., central Connecticut) are
unlikely to attain compliance with the ozone standard unless nearby upwind
AOCRs also attain compliance.
I/ W. S. Cleveland, B. Kleiner, J. E. McRae, and J. L. Warner, "The
Analysis of Ground-Level Ozone Data from New Jersey, New York, Connecticut,
and Massachusetts: Transport from the New York City Metropolitan Area,"
Bell Laboratories, 1975.
TftW** »•>+ \*
ccyy •
-------
Appendix B
As explained in the text in Section C, we wish to substitute a methodology
focusing on expected aggregate unhealthy exposure for EPA's methodology. Our
goci is to try to determine the expected annual number of person-days of
unhealthy exposure to ozone at the alternative standards.
We start with the pattern of the dose-response relationship across the
population. We use median estimates for this example, though a more complete
model would include complete information on the probabilities surrounding this
y
dose-response pattern. At 0.0 ppm, none of the population experiences any
health effect from ozone. At 0.15 ppm. 0.1% of the overall population are
y
likely to be experiencing health effects. At 0.30 ppm, 10% of the overalll
JJ/
population are likely to be experiencing discomfort. These three points can
A/
be used to fit a smooth logit distribution of the following form. :
T i.o + ell.616 - 31.397c (3-1)
where c is the ozone concentration level and P_ is the percentage of the
population experiencing health effects at an ozone concentration level of
c or less.
I/ In the absence of readily available dose-response curves for giver.
individuals and of a readily available weighting scheme for different doses
of ozone for an individual, we have, for the purposes of this example,
used only the critical point, the onset of a health effect.
2J EPA estimates that 5% of the population are asthmatics and others with
chronic breathing problems; perhaps another 5% on average are engaged
in vigorous activity — work or play: and the EPA experts put 0.15 ?pn
as the rough point at which the least sensitive person of the most
sensitive 1% of the sensitive population experiences health effects.
_3_/ This is taken from S. Leung et. al. , Human Health Damages from >to'oile Source Ai
Pollution: A Delphi Study, Corvallis environmental ^esearca i-aaoracary, .3 -^.^ >
April 1977, p. 4.
4/ This "logit form, with these coefficients, fits these three points exactly.
It shows ?T(.37) = .5, whereas Leung et. al. put ?T(..5Q) = .5, but at
the alternative standards which are considered the probability of
occurrences above ozone concentrations of 0.37 ppm is extremely remote, so
this difference is probably not important.
-------
B-2
Next, we cake the Weibull distribution, as suggested by EPA, as
characterizing the distribution of ozone concentration levels over time:
?c = l-e- CSTD (B-2)
where c is the ozone concentration level, CSTQ is the standard, and ?c
is the probability of ozone concentration of c or less occurring in a single
5/
hour. The corresponding density function is
p = ln<8760) m - /ln(8760) • C/CSTD (B-3)
CSTD
The combination of the dose-response relationship and the probability
density of ozone concentrations, when integrated over all ozone concentration
levels, yields the expected person-hours of ozone exposure that is likely to
generate health effects, at any given standard. The expected annual number
of person-hours of unhealthy ozone exposure, then, is
oo
H - 142 x 106 • 8760 I PT • pcdc, (B-4)
o
where 8760 is the number of hours in a year and 142 x 10 is the number of
people living in the 90 AOCRs. H is calculated separately for each alternative
standard. This formulation thus far neglects the geographic variability and
indoor-outdoor differences. In Table 1 in che text, we have assumed, as a
rough approximation, that these factors would reduce the number of person-
hours of unhealthy exposure by 50%.
5/ For the purposes of our calculation, we have assumed that the "shape factor,"
k, in the Weibull distribution, is 1.0. -
-------
"NITED STATES ENVIRONMENT/ TAB T
C21740
Council on Wage and Price Stability/Regulatory DATE: 08 NOV 1979
Analysis Review Group Critique of the Proposed
Ozone Ambient Air Quality Standard Envsronms.-.^
f'''-~- Protection r
h " M: Walter C. Barber, Director ..i^.r Re-;-* *
Office of Air Quality Planning'and Standards
DEC 20 I97f
T0: David G. Hawkins, Assistant Administrator
for Air, Noise, and Radiation LIBRARY
The purpose of this memo is to summarize and respond to the ozone
air quality standard critique prepared by the Regulatory Analysis Review
Group (RARG) and submitted to EPA as a formal comment by Barry P. Bosworth,
Director of the Council on Wage and Price Stability (CWPS).
Summary
The RARG criticizes the EPA decision methodology used in arriving
at its proposed ozone air quality standard. RARG also argues that the
EPA's selection of assumptions results in an overly restrictive standard.
As a part of their critique, RARG suggests both a new methodology and
revised input data that they feel will provide a better assessment for
decision-makers.
RARG contends that a new methodology is necessary because health
effect threshold levels for ozone probably do not exist or are uncertain,
thus prompting the need for other decision criteria such as aggregate
exposure parameters and marginal cost. RARG does not comment on the
disallowance by the Clean Air Act of an economic test to determine the
level of the standard. RARG believes that EPA has over-stated the
seriousness of health effects and the levels at which they occur, and
has underestimated the cost of controlling hydrocarbon emissions. RARG
suggests that based on their interpretation of the economics of health
protection, the proposed ozone air quality standard is too restrictive
and could be relaxed up to a level in the range of 0.15 to 0.16 ppm.
We agree with RARG's comment that economic cost and benefits be
weighed in selecting the secondary standard level. We are reassessing
the need for a secondary standard more restrictive than the primary.
However, we strongly disagree with RARG's suggestion that a simplistic
model be substituted for careful judgment as the principal tool in
selecting the primary standard level.
The following paragraphs characterize both the EPA and RARG ap-
proaches to setting a National Ambient Air Quality Standard as well as
my serious reservations regarding the accuracy and appropriateness of
the RARG comments and suggestions.
EPA F»im 1320-6 (Rev. 6-72)
-------
Characterization of EPA and RARG Standard-Setting Methods
EPA - EPA's approach to setting a- National Ambient Air Quality
Standard is keyed toward the protection of sensitive persons from the
adverse effects of ubiquitous air pollutants. This approach is not
an efficiency optimizing method and it does not take into account
aggregate measures of cost-effectiveness. EPA's interpretation of the
statute does not permit consideration of cost and attainability 1n a
standard decision. We feel Congress has confirmed this interpretation
through its action to extend attainment dates in those cases where
cost or attainability constraints appear unreasonable.
The EPA air quality standard-setting approach attempts to evaluate
all pertinent evidence, and to incorporate it into the final decision.
Selection of an air quality standard with an adequate margin of
safety is a complex judgment that must be based on the careful
consideration of inconclusive scientific and medical evidence. Given
the uncertainty in the available data, the judgments cannot be simpli-
fied to an objective choice based strictly on a comparison of marginal
costs.
RARG - The RARG methodology is keyed to economic efficiency and
resource allocation. This approach focuses on aggregate health impacts
and not on the health of sensitive individuals. The RARG model avoids
complex judgments regarding medical evidence by arbitrarily assigning
no value to less conclusive indications of health risk associated with
low levels of exposure. The RARG approach selects only the most
conclusive studies for use in the cost model and assigns no value to
uncertain risks at lower levels. The RARG further suggests that EPA
move toward a regulatory decision model that equates marginal cost
across different public safety and health programs. RARG argues that
this approach would more equitably distribute public health and safety
dollars among competing programs.
Evaluation of the RARG Report
The RARG report has several principal flaws which strictly limit
its value as an alternative standard-setting methodology or as an
input to a refined or improved EPA standard-setting approach. These
limitations fall in three categories: (1) RARG fails to provide full
consideration and evaluation of the complete array of medical evidence;
(2) the RARG approach is presently illegal; and (3) the control costs
estimates provided by RARG are over-stated.
Full Consideration of all Medical Evidence - The most serious flaw in
the RARG approach is that it tends to oversimplify the National Ambient
Air Quality Standard setting process. It fails to recognize that
complex judgments regarding the full array of medical evidence, both
conclusive and inconclusive, must be considered by the Administrator
-------
in selecting a standard level that protects public health with an
adequate margin of safety. RARG offers a simplistic model which not
only fails to consider these concerns but also precludes them from
consideration by the decision-maker. This principal defect of the RARG
approach is clearly illustrated on page 13 of their report. On that
page and in one paragraph, RARG completely dismisses the entire body of
medical evidence regarding adverse effects attributed to ozone and
photochemical oxidants, with the exception of irrefutable clinical
studies showing effects at concentrations of approximately 0.37 ppm.
Such a choice by RARG totally eliminates from consideration by the
Administrator that body of medical evidence reporting effects at con-
centrations down to 0.10 ppm. (Enclosure 1).
RARG's treatment of inconclusive data and characterization of
ozone-induced effects as short-term, reversible, and with no long-term
debilitating consequences, is not a complete and accurate representation
of the evidence. Decreased resistance to bacterial infection has been
conclusively demonstrated in laboratory animals. The effect in this
case is increased mortality, and as such warrants consideration by the
Administrator in making a standard choice. Animal studies also indicate
that long-term or low-level oxidant exposures seem to act as an inducer
of biochemical and morphological changes. These changes are transient,
and, on a short-term basis, may have a physiological significance in
that they confer a resistance against further lung injury in an oxidant
environment (a similar response has been observed in human clinical
studies). However, the long-term effects of these changes resulting
from a continued exposure are yet to be determined. Whether or not low-
level oxidant exposures can lead to enhanced aging, or a development of
chronic bronchitis or pulmonary carcinoma, fibrosls or emphysema needs
to be determined in long-term tests. RARG erroneously assumes that the
lack of this kind of evidence from definitive human studies indicates
that the effects do not occur. The correct interpretation must be that
the existence of effects is uncertain and that the risk of effects is
real.
RARG has also not considered those studies which show a synergistic
or enhanced effect of ozone in the presence of other pollutants.
Laboratory studies of single pollutants (e.g., ozone in clean, filtered
air), while important in elucidating physiological effects peculiar to
that pollutant, cannot be viewed as providing definitive evidence of the
minimum level at which these effects occur when the source pollutant is
present as a part of the total insult delivered to an individual in the
urban environment. Thus, the effects of ozone must be considered in the
context of the total environment of the exposed individual, including
concentrations of other pollutants consistent with their maximum al-
lowable levels, high relative humidity, high ambient temperatures, and
high levels of physical stress.
-------
Other evidence, erroneously dismissed by RARG, which I feel is
germane to a prudent public health decision on the ozone standard
includes: (1) Symptomatic evidence of ozone toxicity in Japanese school
children and in actively exercising healthy adults after short-term
exposure to ozone levels in the range of 0.10 - 0.15 ppm, (2) reduced
visual acuity in humans at 0.20 ppm, (3) statistically significant blood
biochemical changes in humans at 0.20 - 0.25 ppm, (4) increased sphering
of human red blood cells at 0.25 ppm, and (5) judgments by medical
experts, responsible for conducting medical research, that adverse
effects most likely occur in sensitive subjects at about 0.15 - 0.18
ppm. This evidence plus the concern that effects reported in some
studies may occur at lower concentrations when ozone is in combination
with other urban pollutants, and may be more intense in sensitive
individuals, must be brought to bear on the ozone decision and cannot be
dismissed as suggested by the RARG.
A final note of caution regarding the health data concerns the
simple fact that numerous U.S. cities, where citizens perceive a photo-
chemical oxidant smog problem, record worst day ozone levels (Enclosure
3) that are at concentrations (0.16 ppm) that RARG appears willing to
consider for a standard. Despite RARG's objective of improving and
simplifying the decision process, there is clearly something wrong with
an approach that would characterize present air quality in cities like
Atlanta (Enclosure 3) as currently healthful and safe with an adequate
margin of safety.
Legality of the Suggested RARG Approach - A critical omission of the
RARG report is that it fails to properly deal with the Clean Air Act's
disallowance of weighing of costs in setting National Ambient Air
Quality Standards. Nowhere in the report does RARG recognize this
statutory limitation thus implying that the Agency is without such a
constraint. In promulgating the National Ambient Air Quality Standard
for lead (43 FR 96247), EPA explicitly enunciated its interpretation of
the Act, and thus the official administration position, as disallowing
the use of cost-benefit analysis. Since the CWPS has formally submitted
a statement that conflicts with the EPA position, it could undermine
EPA's interpretation of the statute and its decision on the lead standard.
RARG recommends a methodological approach keyed to resource allo-
cation across different public safety and health programs. Nowhere does
the Act authorize such balancing of costs and benefits across pollutant
and media lines. The Act does not authorize the Administrator to abandon
air pollution control simply because the marginal cost is less for a
comparable health unit in another public health or safety program.
-------
You should also be aware that the President's Council on Environ-
mental Quality has reviewed and critiqued the RARG report (Enclosure 2)
and essentially agrees with our views on RARG's improper treatment of
health data and on their use of marginal cost models to set air quality
standards.
Estimates of Control Costs
The cost figures presented in the EPA paper are based on numerous
calculations, involving many different type sources and projections, all
of which involve uncertainties. The RARG selected two sets of these
calculations for further study and from which it reached the conclusion
that EPA had underestimated the total cost by at least a factor of two.
The two areas addressed by RARG include the Federal Motor Vehicles
Control Program (FMVCP) and Inspection and Maintenance (I&M). The RARG
then uses its calculation of the I&M cost (which contains errors that
will subsequently be discussed) to estimate the cost of controls for
certain other sources. Differences between EPA and RARG cost estimates
are summarized below, followed by a brief discussion of plans to update
the EPA study.
RARG uses a 1974 National Academy of Sciences (MAS) report to
ascertain the cost of meeting a 0.41/3.4/2.0 gram per mile standard for
Light Duty Vehicles (LDV) as $361 per LDV (in 1974 dollars). RARG then
assumes that $60 of this cost is for NOx control. The remaining $301 is
assumed to be for HC control (no adjustment is made for part of the $301
due to CO control). The $301 figure is further revised by assuming that
an additional $30 must be added since the NAS figure is cost above 1970
controls. Finally, RARG adjusted the figure by a factor of 1.33 to
account for new car price escalation between 1974 and 1978--making the
cost of HC control $441 per LDV (1978 dollars).
Although we were aware of the 1974 NAS report, it was not the most
current data available. We elected to use the more recent data, just as
Congress and the Administration did in preparation of the 1977 Clean Air
Act Amendments. This data was generated from studies prepared by the
Office of Mobile Source Air Pollution Control (OMSAPC) which estimated
the cost of controls for LDV's to be $218 per vehicle. Although these
studies cited the $218 value as including both HC and CO control, we
chose not to adjust the figure for CO control. This was done to offset
not being able to account for the cost of the heavy-duty vehicle (HDV)
control as is further discussed below.
It was our judgment that insufficient data existed to estimate the
cost of the heavy duty vehicle and motorcycle (MC) standards. However,
as noted above, it was felt that attributing all of the above $218 cost
for LDV's to HC control, offset most of this omission. RARG
-------
chose to estimate the cost for controls of HDV and motorcycles as equal
to that of the LDV's. Thus, RARG estimates the cost of the HDV's and
motorcycle standards to be $1.7 - $1.8 b.illion and $0.075 billion, re-
spectively.
In the EPA analysis it was estimated that the maintenance cost of
an I&M program would be nearly offset by improved fuel economy—making
the cost of an I&M program about $5.00 per car inspected. RARG uses
results from several recent studies to conclude that only a small portion
of the maintenance costs are offset by improvements in fuel economy.
Consequently, RARG estimates that the I&M cost will be $25 per car.
However, RARG then erroneously applies this value to all cars in the
AQCR--whereas in reality only 30 percent of the cars require maintenance.
Thus, RARG estimates a much larger cost for I&M than does EPA--$1.75
billion vs. $0.23-$0.26 billion. (NOTE: RARG cites EPA's estimates as
$0.35-$0.45 billion for I&M; however, this figure includes both I&M and
other transportation control measures.) RARG extends the I&M program to
include HDV and motorcycles adding an additional $0.61 billion to the
cost of the I&M program. We do not include these controls in our cost
estimates since there are currently no known plans for a HDV and motor-
cycle I&M program.
As you know, OMSAPC just recently updated its cost estimates for
both the FMVCP and I&M. Generally, these new cost estimates are sup-
portive of the values EPA used in its study (in fact the new numbers
indicate that EPA may have overestimated the cost). However, because
there are slight changes in the cost numbers and because improved
emissions inventories have been ascertained, we plan to update our
study.
In the EPA analysis, it was found that even after application of
all definable Reasonably Available Control Techniques (RACT), certain
areas would require additional control for attainment. Because this
additional control has not yet been technically defined, its cost was
estimated as at least $1000/ton. RARG, based upon its erroneous cal-
culation of the I&M cost, estimated that "additional control" would cost
at least $2500/ton. Finally, RARG assumed that an I&M program would be
implemented in all AQCR's studied, whereas EPA included the cost of an
I&M program in an AQCR only if it was determined that such a program
would be needed for attainment.
The table below provides a preliminary estimate of how the revised
EPA analysis will compare with our earlier analysis and with the RARG
estimates in those areas where RARG focused their study. The values for
the updated EPA analysis are based upon the upper limit of cost estimates
for mobile sources as supplied by OMSAPC. For this presentation, we
have chosen to continue to use the $1000/ton value for the identified
RACT since we do not agree with the technique RARG used to determine its
estimate of this cost. We do, however, plan to continue to investigate
this estimate.
-------
. DIFFERENCES BETWEEN EPA AND RARG COST ESTIMATES FOR
CONTROL STRATEGIES EXAMINED BY RARG
(Billions of $)
Earlier EPA Analysis RARG Updated EPAm
Estimates u;
FMVCP (LDV & LOT'S) 3.0<2) 5.6(2) 2.2(3)
HDV and MC 0 1.78 0.78
LDV and LOT I&M 0.26 1.75 0.39
HDV I&M 0 0.61 0
Unidentified RACT^ 0.8 - 3.0 1.8 - 5.9 0.8 - 3.0^
' 'The cost estimates are subject to revision but represent best estimates
at this time.
Figures are based on controls for both HC and CO.
Figure contains only the HC controls.
' 'Upper range based on EKMA; lower range on linear rollback.
' 'We are continuing to investigate this category of sources in an attempt
to better define the costs. The above figures are based upon $1000/ton.
Also, the value shown for the table may change slightly due to several
other parameters which are undergoing slight modifications at this
time (i.e., assumptions regarding background etc.).
Enclosures
cc: Rick Neustadt
Mike Walsh
-------
Co-oi !jtix,ri of -es'ii'S Seaorted in Hunan itudii" nammim Dzone or
Concentration.
ppm
0.01 -
0.30
0.03 -
0.30
0.10
0.10 -
0.15
0.15
0.20
0.20 •
0.25
O.Z5
0.2S
0.25
0.25
C 23
0.30
0.30
0.37
r> } 7
6.37
0.37
C.37
Exposure duration,
hours (for clinical
studies); Averaging
tine (for jpidemio-
logical studies)
bihourly
average
hourly
average
2
probably dally
naxirum hourly
average
1
3
2
2
2 and A
dai iy -.ax mum
hourly average
0.5 - 1
oaily maxmum
instantaneous
(5-ainute)
average
1
dai ly maxinurn
hourly average
2
2
2
2
2
Pollutant Reported
Measured tffect(s)
(0. - ozone.
Ojj = oxidant)
0. Lur-g function parameters in about 25« of Japanese
school cnildien tested /.'ere significantly corre-
lated «ith 0, concentrations (over the range of
0.01 - 0.30J in the 2 hours prior ro testing.
0 Although significant correlation .it; ooserved be-
tween decreased athletic performance 1 0 concen-
trations In the range Of 0 03 - 0.30 ppm. the
Criteria Document concludes that no consistent
linear relationship could be detected below
about 0.10 pom.
0, Decreased 0, pressure in arterial ized olood,
increased airway resistance observed using non-
standard measurement techniques.
Reference(s)
r.agawa and Toyana
(1375). Kagjua. st al.
(1976)
Wayne, et .il .
(1967)
von :;ieding, et al .
(1976)
QX Inci eased rates of respli story synip'..J.mf aiij M«U- M.uino aim MUQ.MCin
ache iere reported by Japanese students on Jays «hen (1975j
0^ concentrations exceeded 0.15 ppm as ccnparec ro
days «inen Ox concentrations .iere less than O.iO pom.
0. Subjective synptoms of discomfort were ooserved by
most subjects, and discernible but not statistical-
ly significant changes in respiratory pattern oc-
curred juhile performing vigorous exercise
0. Reduction in visual acuity (night vision) oo-
served.
0, Asthmatic patients en regions njjini; hi n jxiian. J'ic
DeL'jcia i 4dars
(1977)
Laaer«erff
(1963)
Linn, et al.
(1973)
Hazucna (1973)
(i97=j/> ~:-Lli
Ldnri.iu (1961)
6rn<.ran, H 3'.
(196-)
.. al ,!977)
-------
ENCLOSURE 2
:X£CUTIVE OFFICE OF THE PRESIDENT
ON CNVlPONMfiNTAI. QUALITY
, 0. C 27335
October.18, 1978
MEMORANDUM FOR WILLIAM D.'NORDHAUS
Council of Tconomic Advisors
^-.-/^rrrv-^ .
Comments on RRHG Report on EPA's Ozone
Standard Proposal
Attached are CEQ's comments on the subject report.
appreciate this opportunity to cojfuf.ent-.
cc: Dave
Bill Drayton
(H.
-------
Comments From CHQ on the
Draft RARG Soport on. EPA's
Ozone Proposal
1. v:e do not believe that tha report properly deals with
tho Clean Air Act's intent that costs, should not be a primary
consideration in setting health related standards. Although
we recognize that some cost onalyr.is is necessary to dor.crmina
the tradeoffs between uncertainty and public health protection
und^r the no threshold approach, nuch data should only be used
consistent -with statutory requirements. EPA is the agency
charged with interpretation of the statute and has determined
that cost analysis r.hall be precluded as a direct consideration.
EPA enunciated f.his precedent in sotting the ambient standard
for lead. Section 109 of the Act directs that ambient stanSaic?
bo sot at a level which will be protective of public health
with an adequate jnaryin of nafoty. WG feel that the RAi*G report,
by emphasizing morginal, oconomic costs and benefits, is
inconsistent vith t.hc intent of thn Act .ind the Aclmi niotration ' i>
current intorpretation of its provisions.
2. The report seems to be deficient in its discussion of
EPA's health effects dot*. It discredits the validity of
sever.il .stxidics in order to suggest, thnt 0.15 is not the lower
liriut of observed effects on human health. The report suggests
»
that if the observed threshold were higher, thon Lhe standard
coul
-------
agroo with this argunsnt . Although questions have been raised
about the studios which show physiological effects below .15
ppm, they cannot be dismissed out of hano. Further, tha
aniinal toxicology data cannot bo ignored which show effects
at 0.10 ppm. Ue recognize that animal data is not directly
translatable to huiiiari effects, but such data confirms that
effects can occur at low exposure levels. Therefore, EPA
roust bf» prudent in its interpretation of available health
effects information.
3. CKQ agrees with the report th.it nn Actual population
fjxpopure risk analysis would proviuc greater insight into
the iTingnitviue of the Cation's o^onc problem. Ifowcvor, I. ho
stat<2 of the art of such analysis i s in i Us infancy. EPA
must operate ujider the time constr.Tintc imposed by the 7*ct
vhich precluded the TlovcJ opncn t ancl execution of such nn^l
Rsthrjr than specirically critirr-i^c i-his particular reoulatory
action we suggest that the rncthodoJ ogy proposed in the report
ba loo/tcd upon an objective for futvire environmental impact
analysis .
4. Although we* have so?na dasaijre«jT«»nts with thr; report as
noted nbove we feel that thra report was very well prepared.
-------
DAUA KOKST CASi: 1970 O.'CKii: CONCUTKA1 lU»-> Lli ihLi:i:itJ UillMJJ A
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-------
IJAILY I.OKbl' CASi. l'j;6 (S/.0.3L Cu.VLNi K/il i-O.'JS IN SLlLoltU Ui'.M1 «Hl
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The monitoring sitc<> selected uere those with the highest daily maximum hour ozone concentration in 1976 which Mere located in the principal urban core
area having at ledst flOi (290 days) of the days monitored in the year. Since no ozone data was available for Atlanta, GA, the site in Decatur, GA -tith
only 187 days of d.tta is shown. This may overestimate the ozone problem in Atlanta. The Lowell, MA site is shown because ozone is monitored there only
throughout the ozone season (Apr-Get) and this distribution reflects the high ozone days.
bTlUs summury reprtsuncs 19?7 ilaca vhlcli was used because die 1976 data were questionable.
-------
UNITED STATES ENVIRONMEN "
p TAB U
^ (Currently under Revision)
'
SUBJECT Estimate of Economic Benefits Associauad with Alternative Secondary
Ozone Standards
Environmsr.
KROM Harvey Richmond protection A^-
Pollutant Strategies Branch Re»icn p
T0 Mikp Jones QEC 20 I97t
Pollutant Strategies Branch
J.IBRARY
1.0 Introduction
It has been found that ambient concentrations of ozone are ro-
sponsible for economic losses that arise from accelerated aging of
certain materials (e.g., rubber cracking, dye fading, and paint
weatnenng), damage to vegetation (e.g., foliar injury, growth
reduction, and yield reduction), and reduction in visibility. This
analysis attempts to quantitatively assess the difference in economic
loss associated with alternative secondary ozone standards.
Only crude estimates were possible for the reduction in economic
aaj:;j(jc to forest products and ornamentals. The analysis used a first-
cut approach to obtain an upper boundary estimate on reduction of
damage for major farm crops. Reduction in ozone damage is estimated
for 350.6 billion of the $54.6 billion (1977 value of production)
in major farm crops for which the U.S. Department of Agriculture
keeps economic data (reference 3). For the 5 crops that accounted
for the bulk of the difference in economic loss, and for other
crcp-j ")r winch the first-cut approach was not helpful, v/e consulted
with bcvero'i plant pathologists to obtain an improved estimate for
reduction in damage. For materials anu visibility v/e concluded there is
i-o difference in economic damaqe between the alternative standards.
.•-
-------
2.0 Method of Analysis for Determining Reduction in Economic
Loss For Commercially Important Crops
The support and criteria documents (references 1, 2) estimate
that ozone-related damage to vegetation may be approaching $300
million (1974 dollars) at the farm level. The goal of this analysis
is to estimate the incremental reduction in damage that would result
from adoption of alternative secondary standards (0.08 ppm/1-hour,
0.10 ppm/1-hour, or 0.12 ppm/1-hour).
At ozone concentration levels in the range of 0.05 - 0.12 ppm
it is the 8-hour average, not the 1-hour average, which is significant
in determining the amount of damage to vegetation. An analysis of
available air quality data indicated that attainment of a 0.12 ppm/
1-hour average standard would prevent an 8-hour average concentration
of 0.10 ppm from being exceeded more than once per year. A 0.10 ppm/
1-hour average standard would prevent an 8-hour average of about 0.09
ppm from being exceeded more than once per year. Similarly an 0.08 ppm/
1-hour average standard would prevent an 8-hour average of about
0.07 ppm from being exceeded more than once per year. The remainder
of this report is based upon two comparisons: (1) allowing only one
0.10 ppm/8-hour versus 0.09 ppm/8-hour peak exposure per year and
(2) allowing only one 0.09 ppm/3-hour versus 0.07 ppm/8-hour peak
exposure per year.
In order to evaluate the difference in economic damages between
alternative standard levels, it is necessary to have a dose-response
-------
function relating ozone concentrations and duration of exposure to
percent yield reduction or damage. Heck and Tingey have developed
a mathematical model that quantitatively predicts the extent of
foliar injury in certain classes of crops due to single, acute
exposures as a function of ozone concentration and exposure time
(See Table 11-5, reference 2).
However, foliar injury is an imprecise measure of the effect 01
ozone on plant growth and/or yield. Work has been started by
researchers, such as Ron Oshima, (U. Calif.) and Al Heagle, (N.C.
State), to obtain dose/response relationships for ozone in terms
of yield reduction; however, very little data from these new experi-
ments are currently available. It is thus necessary to utilize the
foliar injury response to evaluate alternative levels of the secondary
standard.
For the purposes of this analysis, a first-round estimate is made
based on the assumption that the acute foliar injury response to the
peak exposure permitted by the standard can be used to predict biomcss
(growth) reduction (and presumably yield reduction or economic damage)
caused by chronic exposure to ozone levels up to and including the peak
value permitted by the standard. We consulted Or. Ray Wilhour (U.S.
EPA-Corvallis) regarding this important assumption. He recommended
that we recognize the uncertainty involved in this assumption by pre-
senting a range in the damage estimates. His best quess was tliat
the ratio of the percent damage (yield reduction) to acute foliar
injury percentage may be as low as 1:1 or as high as d:\.
-------
In discussions with plant pathologists around the country, we
were cautioned.that_while there appears to be a fair amount of
correlation between foliar injury percentage and biomass reduction,
there is a great degree of variability in the relationship between
biomass reduction and reduction in yield (the economically important
parameter for most crops). For example, significant damage or yield
reduction can occur in some crops without any noticeable foliar
injury. In contrast, it is possible to have significant foliar
injury and biomass reduction and yet have no noticeable effect on
yield. The timing of an air pollution episode in the crop's life
cycle and the presence of other environmental stresses (e.g., drought
conditions) are often crucial determinants of how much yield and/or
biomass reduction will result from a given degree of foliar injury.
In considering the results of this analysis, the above caution should be
kept in mind.
Another important caveat is the fact that the Heck and Tunjey
equations were derived from studies which generally exposed plants in
greenhouses under the most likely conditions to produce injury (e.g.,
high humidity, high soil moisture, and medium temperature). The levels
of injury suggested by the Heck and Tingey model almost certainly
exaggerate the amount of damage for the significant portion of the U.S.
crop which is grown under less sensitive conditions (e.g., low humidity,
low soil moisture). These less sensitive conditions are particularly
found in the central and northern plains regions of the United States.
-------
The commercial crops studied are divided into the following
categories depending upon which part of the plant is of economic
value: foliar (tobacco, broccoli), seed (corn, wheat), root (radish,
onion) and fruit (oranges, cucumber). For foliar type crops it is
assumed that there is no threshold, i.e., any foliar injury percentage
will result in some economic damage. However, for non-foliar type crops
the assumption made is that only foliar injury in excess of 5 percent
will lead to yield reduction or economic damage. This 5 percent
threshold is based on the comments of several researchers to the
effect that 5 percent foliar injury is usually required before there
is a detectable reduction in biomass and/or yield in sensitive plants.
Using the above assumptions a percent damage is determined using
the equations in Table 11-5 for each major commercial crop known to be
sensitive to low ozone levels and for which economic data is readily
available. The difference in percent damage associated with allenialivc
standard levels is listed in Tables 2 and 3 as A % damage.
The data needed to enable conversion of A % damage to a dollar
value estimate are:
(1) the economic value of production of each crop at the farm
level;
(2) the percentage of each crop that is of a sensitive or
intermediate cultivar (i.e., variety).
The production value of each major crop is obtained from the U.S.
Department of Agriculture (reference 3) and is in terms of 1977 production
and dollars. A first-cut, systematic estimate of the share of the total
-------
6
crop that is of a sensitive (or intermediate) variety is calculated
by one of two methods. Both methods rely on Table 11-24 in the MAS
ozone document (reference 4) which categorizes the varieties examined
by plant researchers as sensitive, intermediate, or resistant. Where
four or more cultivars for a crop are listed, it is assumed that the
percent of sensitive (intermediate) cultivars for that crop (as reported
in Table 11-24) is equivalent to the sensitive (intermediate) fraction
of the crop presently being grown on the nation's farms. So if 12
cultivars for oats are listed and 6 of them are in the sensitive
category, then 6/12 or 50 percent of the oats grown are assumed to be
of the sensitive variety. Where fewer than 4 cultivars of a given
crop are listed, a percentage of sensitive cultivars for that type of
crop (i.e., seed, foliar, fruit, or root) is used to determine the
share of the crop that is sensitive. For example, fewer than 4 cullivars
are listed for sweet corn in Table 11-24, but 24 percent of the seed-type
cultivars fall in the sensitive category. Therefore, it is assumed
that roughly 24 percent of the sweet corn grown is of a sensitive
variety.
Utilizing the above estimates and the assumptions they are based
upon, the difference in economic loss between two alternative ozone standards
is calculated by multiplying the difference in percent damage for the
sensitive crops, the share of the crop that is sensitive, and the
economic value of the total production at the farm level for each crop
-------
and multiplying the difference in percent damage for the
intermediate crop, the share of the crop that is intermediate,
and the economic value of the total production at the farm level
for each crop, and summing the products for all major commercial crops.
n
A Economic Loss = Z (A % Damage (% of crop that is) (1977 value
(1977 dollars and i=l for sensi- sensitive) of production
production) tive cropi) for crop i)
+ (A % Damage (% of crop that (1977 value of
for inter- is intermediate) production for
mediate crop .i) cr°P i)
In determining the reduction in economic loss associated with a 0.07
ppm/8-hour as opposed to a 0.09 ppm/8-hour standard, it is found that
for crops of intermediate sensitivity the A % damage is zero or nearly zero
for the crops considered. Thus no loss data for intermediate crops appears
in Table 2. However, as one compares a .09 ppm/8-hour and a .10 ppm/8-hour
standard, ozone damage to intermediate crops should be considered because
the 5% injury threshold is generally exceeded for a peak exposure of
0.09 ppm/8-hour average or greater.
The above estimate of the annual difference in economic loss
associated with alternative standards assumes that production will
remain at 1977 levels and that the value or price per unit for each
crop would remain unchanged even if more of the crop were produced due
to reduced ozone levels.
-------
8
3.0 Economic Loss to Commercial Farm Crops
Using the above mentioned assumptions an upper-boundary (worst-
case) estimate was made to identify which crops might be responsible
for the bulk of the reduction in economic damages. It was found
that the vast majority of the estimated economic loss was accounted
for by the following 5 crops: corn for grain, hay, soybeans, tobacco,
and wheat. In addition, the systematic approach outlined above was not
helpful in providing even a first-cut estimate for several important
crops, of which cotton was the most prominent in terms of the total
production value. Therefore, in order to obtain more realistic estimates
of the reduction in damage to these major farm crops associated with
alternative standards, various plant experts were consulted with on the
assumptions used in the initial analysis and the total values obtained.
Based on these conversations, the first-cut estimates were revised for corn
and tobacco, and original estimates were made for cotton and several other
crops. These improved results are shown in Tables 2 and 3. The following
paragraphs detail the bases for these revisions.
Al Heagle, a plant pathologist at N.C. State, has suggested that
the percent of field corn (corn for grain) that is of a sensitive variety
is probably on the order of one-half of the percentage of sweet corn
that is sensitive. Since the systematic estimate of this percentage was
the same for both crops (24 percent), this recommendation lov/ered the
damage estimates for field corn by 50 percent from the first-cut estimate.
Thus, Table 2 gives a range of $77 million to $155 million as the re-
duction in damage for attaining a 0.07 ppm/8-hr as opposed to a 0.09 ppm/
3-hr peak exposure.
-------
The initial crude estimate of the incremental reduction in damage
to tobacco was estimated to be from $94 to 5186 million (0.09/8-hour
0.07/8-hour). This was based on the systematic estimate that 70 percent
of the tobacco crop is of a sensitive variety. This esLimale is almost
certainly too high. In North Carolina, where nearly 50% of the U.S.
tobacco crop is grown, the maximum annual damage attributed to ozone in
the period 1973 - 1977 occurred in 1976. The estimated diseases loss
was only 0.38 percent or $3.655 million for that year (reference 5).
Dr. Todd of N.C. State estimated in personal communications that about
28 percent of the North Carolina flue-cured tobacco crop (types 11 - 14)
was Speight G-28 and that this variety was the most sensitive of the
flue-cured types presently grown. However, he believed that Speight G-28
would fall in the intermediate category using the NAS classification
system. Dr. Todd also mentioned that most of the ozone (weather fleck)
damage was to the lower leaves of the tobacco plants. There is currently
a surplus of these leaves on the market and farmers are being encouraged
to destroy these leaves. Thus at present there is little if any ozone
related economic damage to the tobacco crop in North Carolina.
For Burley Type 31 tobacco, which makes up roughly 31 percent of
total tobacco crop, Dr. Hadden (Univ. of Tennessee) estimates that
the maximum weather fleck (ozone) damage suffered in recent years
was around 0.5 percent of the crop. Since Burley Type 31 and flue-
cured types 11-14 make up 91 percent of the total tobacco grown and
are of intermediate or resistant susceptibility to ozone, something
less than 9 percent of the tobacco crop could be of a sensitive variety.
-------
10
If the remaining 9 percent of the tobacco crop were of a sensitive
type, then the reduction in tobacco damage from adopting a 0.07 ppm/
8-hr peak exposure standard instead of an 0.09 ppm/8-hour average
standard would be estimated to range from 12 to 24 million dollars
using the methodology described previously.
Dr. Todd also estimated that 26 percent of the total tobacco crop
nationwide was of an intermediate variety. This value is used in
generating the reduction-in-loss estimate in Table 3 for intermediate
type tobacco.
Finally, we consulted H.E. Heggestad of the U.S. Department of
Agriculture at Beltsville, MD regarding his work with cotton. While he
noted that some cultivars were found to be more sensitive than others,
he offered his judgment that no cotton tested would show a difference
in yield for either of the alternative standards. Tables 2 and 3 reflect
his judgment.
Heggestad further commented that the entire approach taken in
this analysis grossly overestimates the differences in economic damage
between the alternative standards. He based this coiiiinenl on (1) the
fact that this analysis extrapolates acute foliar injury results obtained
in greenhouses under sensitive conditions to yield reductions in the
field, (2) his belief that our correlation of 1-hour to 8-hour
average peak concentrations produces higher 8-hour average levels than
he has observed, and (3) his own experience with field tests of crops
-------
11
such as cotton, snap beans, and potatoes1. His judgment on this
matter is summarized as follows: he feels that maintaining the
secondary standard lower than the proposed primary standard of 0.10
ppm / 1-hour average cannot be justified on the basis of protecting
farm crops from economic damage. At the time of consultation, he had
not yet formed an opinion regarding the possibility of setting the
secondary standard as high as 0.12 ppm/ 1-hour average.
4.0 Ozone Damage to Other Vegetation
This report has made quantitative estimates of the reduction in
damage to commercial farm crops which would result from attainment of
alternative ozone standards. It should be realized that current ambient
ozone levels also cause damage to our national forests and parks, to com-
mercial timber growth, and to commercial and home-grown ornamentals.
As the support document states, "it is very difficult Lo quantify
adequately the importance of natural ecosystems tu the public welfare,
and consequently to provide monetary estimates of the impacts of oxidant
pollution on natural ecosystems" (reference 1).
Using the systematic methodology discussed previously for farm
crops, a very crude (worst-case) estimate can be made of the maximum
reduction in damage to all commercial forestry and ornamental products
associated with the alternative standards. In 1972, the total value
for all commercial forestry products was S2.9 billion. If the
oercentage of the sensitive trees grown is equivalent to the fraction of
tree species listed in Table 11-24 (reference 4) that are sensitive
(20%) anJ the difference in damage for the 0.09 ppm vs. 0.07 ppm/0-hr
-------
12
levels is about 5 percent (the value obtained using the all-sensitive-
plants equation), then for the case where percent yield reduction
is assumed to equal % foliar injury, the reduction in damage is:
(20%) (5%) ($2.9 billion) = $29 million (1972 dollars)
Thus, the range of the estimate given in Table 2 is S29-58 million
(0.09ppm/8-hr - 0.07ppm/8-hr.
A similar crude estimate can be made for commercial ornamentals
and shrubs:
(19%) (5%) (SI.3 billion) = $6.5 million (1974 dollars) ( .09?pm/8-hrs
.07ppm/8-hr).
The range of the estimated reduction in damage to ornamentals would be
S6 - $13 million for attainment of a .07 ppm/8-hour standard as opposed
to a .09 pprn/8-hour standard.
Quantitative estimates of damage to home-grown crops, ornamentals,
and shrubs were not made due both to the lack of information on how
much of each type of vegetation is grown and the difficulty of
placing an economic value estimate on damage to shrubs and plants.
These plants may be damayed by ozone such that their appearance is
marred but still the plant continues to survive. Since these plants
are not subject to any market mechanism, it is very difficult to place
an economic value on the partial damage that is caused by exposure to
ozone.
5.0 Ozone Carnage to Materials and Reduction in Visioiluy
In the case of materials damage any non-zero ozone concentration
will contribute to the deterioration of sensitive materials if the exposure
-------
13
is long enough. As described in the support document (reference 1)
the annual average concentration, not a short-term peak exposure, will
determine the rate at which material damage occurs. While peak 1-hour
concentrations of ozone tend to be higher in urban areas, rural areas
remote from man-made emission sources have been found to have similar
annual averages. This is due to the nightime scavenging of ozone by
man-made pollutants (NO , HC) in the urban areas. Thus, reducing the
^
annual peak exposure by 0.02 ppm or 0.04 ppm is not likely to result
in a detectably lower annual average. Since it is projected that there
is no difference in the annual averages associated with the alternative
standards, it is estimated that there is no difference in the materials
damage that will result from either standard.
The impact on visibility of adopting an 0.08 ppm/1 hour, 0.10 ppm/
1-hour, or 0.12 ppm/1 hour ozone standard cannot be accurately determined
based on the current state of knowledge. However, figure 3-4 in the
NAS document (reference 4) seems to indicate thai at levels up to
0.12 ppm ozone, there is no measurable impact on visibility.
6.0 Summary and Observations
Utilizing the assumptions and methodology described previously,
it is estimated that the maximum benefit (in terms of reduced damage
to all commercial types of vegetation) associated with a 0.08 ppm/
1-hour standard as opposed to a 0.10 ppm/1 hour standard, is from
-S466--- 932 million . The maximum benefit of adopting a 0.10 ppm/1 hour
standard as opposed to a 0.12 ppm/1-hour standard is estimated to be from
S665 - 1,330 million. It should be remembered that the above estimates
-------
14
are likely to be worst-case, upper-boundary values and do not
represent our best judgment of the most likely economic damage asso-
ciated with alternative standards.
References
1. U.S. Environmental Protection Agency, Assessment of Welfare
Effects and the Secondary Air Quality Standard for Ozone,
June 1978.
2. U.S. Environmental Protection Agency, Air Quality Criteria
for Ozone and other Photochemical Oxidants. Publication
No. EPA-600/8-78-004, April 1978 (preprint).
3. Department of Agriculture, Crop Values 1975-1976-1977, Washington,
O.C., January 18, 1978.
4. National Academy of Sciences (NAS) Ozone and other Photochemical
Oxidants. NAS, Washington, O.C. 1977.
5. Todd, Furney, Extension-Research on Wheels: Summary Report of
1977 Data, North Carolina Agricultural Extension Service,
November, 1977.
-------
TABLE J
SELECTED VEGETATION GENERA AND SPECIES GROUPED liY
SENSITIVITY TO OZ0NE
Sensitive Intermediate Resistant
Bean (4)a Bean (5) Bean (5)
Cucfcumber (1) Cucfumber (2) Cucmimber (1)
Oats (6) Oats (5) Oats (1)
Soybean (14) Soybean (19) Soybean (6)
Spinach (4) Spinach (3) Spinach (1)
Tobacco (35) Tobacco (12) Tobacco (1)
Tomato (7) Tomato (6) TuimiLo (3)
Numbers in parentheses ( ) are the numbers of varieties of thu apocLcs
for which reports of ozone response t/ere re
-------
Table 11-5. CONCENTRATION. 1IMC, FILSPONSL EQUATIONS FOR THREE SUSCEPTIBILITY
GROWS AMD TOil SaCClCO I'lAfllS Ull PLAN! TYITS WITH KESPICT TO OZONE
Plants (C=A0 < A, I + A?/T)b
Sensitive
All plants -0.0152 + 0.00101
Grasses -0 0:JG5 + 0.00401
Lcgj-os 0 0152 + 0.0(1361
TO«J:O -0 0023 + 0.00431
Cat -0.0-127 * 0.00511
Bean -0.0090 T 0.00301
Tobacco 0.0245 + 0.00341
Interrelate
All plants 0.0244 + 0.00651
Vcge'iblus -0.0079 + 0.006-11
Grasses 0.0107 + 0.00591
Legits 0.0116 + 0.007-11
- Fere -.rial 0.0748 + 0.00701
I. Clc.er -0.0099 + 0.00711
0 Utit -0.0036 + 0.00811
lco::-o 0.0631 i 0.00871
Re si s t j-'.t
All r- lints 0.1 6B9 + 0.00951
Lee- '-s 0 0090 " 0.01021
Grists 0.1906 + 0.0117!
U-gi-isDles 0.1979 + 0.012CI
pii.its 0.2312 + O.OOt-11
CUC---.LI- 0.1505 + 0.01411
Chi • :jnthc~u:r
0.2060 + 0.00521
+
+
t
t
+
+
4
+
+
+
+
f
\
+
t
+
•i-
+
+
+
+
+
0.213/T
0.291/1
0.172/T
0.243/T
0.273/T
0.164/T
0.137/T
0.290/T
0.263/T
0.292/T
0.32S/T
0.237/T
0.262/T
0.302/T
0.152/T
0.278/T
0.304/T
0.263/T
0.107/T
0.205,/T
0 106/T
0.256/7
pC
0.57
0.74
0.46
0-50
0.76
0.58
0.52
0.74
0.79
0.02
0.81
0.77
0.95
0.68
0.70
0.51
O.B2
0.55
0.70
0.45
0,63
0.40
Threshold ^
conr«!iilrdLlon , p_[iir" _ No. daU
Tlir 4~hr " ~0"lir points
0.22
0.1'G
0.2-1
0.10
0.26
0.17
0.18
0.35
0.29
C.33
0.38
0.35
0.29
0.34
0.26
0.50
0.45
0.51
0.38
0.47
0.33
0.49
0.06
0.04
0.11
None
O.OG
O.Ob
G.08
0.13
0.09
0.11
0.13
0.17
0.09
0.11
0.14
0.27
0.22
0.31
0.29
0.31
0.25
0.30
0.03
0.01
0.09
llOltC
C.02
0.03
0.06
0.09
0.06
0.09
0.09
0.14
' 0.06
0.08
0,13
0.25
0.1G
0.20
0.20
0.30
0.23
0.27
471
71
100
20
'30
62
197
373
25
66
104
27
24
15
59
291
36
13
16
46
16
45
Moan values0
Cone. ( C J , 1 1 me ( T )
ppni hr
0.29
0.37 '
0.34
0.31
0.37
0.30
0.23
0.37
0.41
0:39
0.40
0.36
0.28
0.47
0.20
0.<5
0.30
0.45
0.55
0.39
0.41
0.39
1.74
1.66
1.42
1.50
1.66
1.23
1.90
1.67
1.29
1.61
1-59
1.91
2.13
1.25
1.99
1.55
1.69
1.47
1.50
2.50
1.41
2.17
, Responsc(l
45.4
50.9
40.1
56.5
40.2
47.2
38.9
27.0
33.5
31.0
25.0
22.9
23.0
28.9
15.7
10.6
12.2
6.5
17.6
7.8
13.3
12.6
[), Dose,
pfm-hr
0.503
0.608
0.480
0.491
0.611
0.370
0.448
O.G25
0.532
o.:::
0.642
0.687
0.595
0.5C8
0.551
0.696
0.722
0.655
0.819
0.905
0.581
0.847
-------
equations vert? developed from exposures limited in time (0.5 to 8 nr, except for 2 to 12 lir points in
the sensitue group) arid denote acute responses of the plants. Concentrations range from 0.05 to
0.99 (1.0) ppm and responses from 0 to 99 (IQO)X of control. Reference 3.
*C 1s ozone concentration in ppm; I is percent injury; T is Mme in hours; and AQ, A,, and A,
are constants (partial regression coefficients) that are specific for pollut.ml, plant spectes or
group of species, and environmental conditions used.
'Multiple .correlation coefficient squared, which represents the percent variation explained by the
model.
For 5t response in 1, 4, and 0 hr periods.
"From the ccir.puter analysis.
-------
to Tann Crop*, Forest
ELitiNialct of UeilucLion in I rniiuunt. I'-wiiy
*, Forest Prnilucli. and Ornamentals ( 'I/-.OT)
1 1'
' i'i -, ' • , /
.Kill 1 1 'll
1 1
II • 1 1 II 1 1
•• 1
•
.07 .09
'•ll/'. ,11 '. Ml.ll/ !l| •
0|'p1e«: (O) 14.6
l»ii» ley (s)
14.6
be*ns, dry ,„ ,
eihble (s) y>J
broccoli (F
14.6
..
1. ill ,t
III, HI 1
: iii»i i. M>
il 1 I
Yll'l'l ' •• -I » I'll!
(,' !! ) hi, ill,
1 yi>» ••• -MI v :•
il ••''-.
•
»"
.07 .09
|i| .,!/ In •; nr if '.. ,
ii
Y ' 1 1
J
19.6 all sens. 9.6
19.6
i
• i
. i i.gi
( ill 1 1 n.,i )
14.6 5.0 6? I.I)
plants
all sens. 9.6
P 1 an is -
-, - all sens. ,. _"
CO . C. N 1*1 . 3
Ibcans
,„ , all sens." ,,. ,
]9'6 (plants ...1*'.6 .
| cabbage (f) 14.6 ! 19.6
coin. For
tjraiii (s)
corn, sweet
(s)
col ton
cucun'bpr
grapes (Fr)
14. 6
14.6
~
19.6"
19.6
14.6
14. f.
hay (F) IB. 8
oats (s)
i
onions {r)
19.6
19.6
all sens. ,. ,
plants , 14'6
all sens.
plants
all sens.
plants
all sens.
plants
all sens.
plants
"all sens.
"•' (grasses
15.4 19.3
14.6
orancies ,. ,
f r \ 1*1.1)
(f» J . - -
pcatiuls Is)
U.6
"9.6
9.6
9.6
9.6
10.0
all sens. ( ,Q „
oats |
,„ e al 1 sens. • Q n
,19'6 Iplanljs.. | 9*6
"•6 plants . . '
"l9.6
all sens. 1 „ ,
plants y._
14.6
19.6
19.6
14.6
14.6
5.0
5-0
5.0
713.7
35C 3
Ofl.O
176.1
5.0 , 12,OC7.0
5.0 220.3
0
14.6
5.0
14.6 | 5-0
22.9 , 4.1
4,013.7
13C.5
776.1
6.741.7
U.3 j 3.9 B53.4
14. 6 ; 5.0
U.6 ' 5.0
u.6 ' r>.o
227.1
64n.i
770.9
,
•nil 1 1 .1
t r>F Ci np i '
1.1, a 1 K; | .,,.,.
rcn'-iliuo i(|i|lu,ii
-------
TAULC 2 (cont.)
Revised CstimaLes of Reduction in Economic Damage
lo Farm Crops, forest Products, ami Oinamentals (.07*.09)
1 ''i
,
.11
II t , .11
'
poUtues
rice (s)
sorghum (s)
1
soybeans! s)
• ipltMi.ll (f )
1
InlKirco (f)
1 umd 1 (> ( f I )
i
wlit'dts (s)
ru()
' I'll.1! 1 y
'.' ' l
.07 .09
i.|in/.? in •, |>i>ii,/:;'ii s
14.6
14.6
14.6
0.9
14.6
8.4
2«.3
•
14.6
(farm ft ops j
i
t inus I
( riips
(II IMIIIL'Ill ills
•Hill Sill UllS
14.6
10. 6
i
IOIALS
f
19.6
19.6
.
..ii'ii ii- ul
•••|.| I' I.HI .
1 • •!
l»l Lll
IllJ.ir"/
all sens.
plants
all sens.
plants
19 6 a" sens-
Iplatits
G.5
19.6
.4.2
33.0
19.6
-
all sens.
1 eyiiines
at l sens."
plants
all sens'
1 obacco _
al1"s"ens~.
tomato
all'sens.
plants
.
in c al 1 SCilS.
l9'6 ||,1anLs
19.6
-
•
all sens.
plants
-
,
4 iMin.nji? (ni i .
Y'rl.l ft,., •! t |,l|l
; .' R j in. loii i,-
I y\t>! < i >MI| Y :<
I.I. - ^ •.}•'. \ ui
•"'•- )
.07 .09
(ii-.il/irtii '.
9.6
9.6
9.6
0.0
14.6
" 8.4
23.3
9.6
-
14.6
14.6
i
iii'in/1 In
14.6
14.6
14.6
1.5
19.6
14.2
28.0
14.6
.
,:,..ij,-
H
Y H -:" i
5.0
5.0
5'°.
1.5
5.0
5.8
• i _ It|
. M.|>
{Mil 1 1 liiMS)
1.275.3
920.7
1.357.3
9.945.0
24.0
2.293.8
4.7 914.1
5.0
i
19.6 ; 5.0
l'J.6 5.0
!
...
i
4,677.0
50. 647. 5
2,900.0
1,300.0
-
1
.. .
t uf Cio
that is
sensitive
25.0
24.0
24.0
36.0
50.0
9.0
44.0
24.0
A>.0
9.0
_
• i. • . i
.. < i i ,
{Millions
310. 8
222.9
325.0
3. 500. 2
12.0
206.4
402.2
1.122.5
•
500.0
117.0
"i
— -- -
.......
millions)
Y H 1 1 r „• t 1
II .1
15.9
11.1
16.3
53.7
.6
12.0
10.9
56.1
- -
431.4
29.0
b.9
-- - - - —
l 466. J
31.9
?2.3
32.6
107.4
1.2
J4.0
37 »
112.2
802.11
M.O
II.H
HV.6
-------
TABU 3
Revised Estimates of Reduction in economic liomaijc
to farm Crops, Forest Products,, anil Ornamentals (.09».10)
'I.1
I .ml
> i i
apples (fr)
apples (fr)
barley (s)
bai ley (s)
bean1., rli y
i c'hlile (s)
beans, dry
i edible (s)
luucrol i ,f .
brociol i . . .
(.nbbiUjij ( f )
(.abbdcje (f)
corn, foi
ijrciin (s)
Lorn, for
> y> am (s)
1 ( orn, sweet
(s)
coin, sweet
(>)
11.6
0.0
11.6
0.0
21. 2
0.0
19.6
1.5
I9.6
1.5
11.6
0.0
11.6
0.0
(if I .I.
MI I i. -n
r I ii I i. n
is I i \\
1 n'. 'in
i • •)
1 /
.10
1 1 "/'• i'l '.
. I7'1
1.1
.!'•'.'
1.1
?1.5
1.1
22.1
6.1
22.1
6.1
17.1
1.1
17.1
1J
-
,' - •. ji-
il
(M.\ 1.
2.5
. V
"
1.1
3.3
.. . !•! _
2.5
1.6
2.5
1.6
2.5
I.I
2.5
1.1
0
i • In-- nl
i nip
(. II III. Ml'.)
621.0
621.0
713.7
7,3.7"
358.3
350.3
08.0
88.0
176.1
176.1
12,887.0
12. 8117. 0
2?0.3
^0.3
1.013.7
.'. "i i 1 1 |i
I'.il 1',
•II III /(••
IH ( Mil -I
H;I ill id1)
25.0
(25.0)
21.0
(63.0)
23.0
(38.0)
5I.O
(32.0)
5I.O
(32.0)
12.0
(63.0)
21.0
(63.0)
0
-
Value of
Sensitive
( Interme-
diate)
Crop
SMilhons)
155.3
(155.3)
171.3
(119.6)
8?.1
(136.2)
11.9
(28.2)
U9.8
(b6.1)
1.516.1
[a. no. a)
52.9
(130.0)
0
•'S
Y.K. I I
l-l
3.9
1. 7
1.3
5.0
2.7
1. 9
I.I
.5
2.2
.. •*.' "
30.7
H9.3
I.3
I 5
n
111 I ions)
t : i
.' 1
7.8
3 1
8.6
IO.O
5 1
3. l«
2 2
1.0
1.1
1. 8
77 4
l/U.G
2.6
J.O
0
-------
TABLE 3 (Conl.)
lie vised Eslnnat.es of ReJucLion in
to Fann Crops, I'orest Products, anil Or
Economic Damage
nanientals (.09 •» .10)
1 i,TI'
1 ! l
1 II
1 i 1 • ml
'. 1
1
cuciiinburp .
cucuiTrbcr
(fr)
yiapes (fr)
y rapes (fr)
hay (f)
hay (f)
oats (s)
Odls (s)
unions (r)
on KIIV, (i )
ordiujcs
(ft)
01 JlKJuS
(f'l
pi.'dimts (s)
loryluiin . .
sonjliuiii (s)
•' i J|
' 1 UP
(Vli II inn.)
136.5
136.5
776.1
;__
6,741.7
6.741.7
853.4
«53.4
227.1
227.1
648.5
648.5
7/0.9
1,357.3
1.157.3
'', nl 1 Hip
II. .1 Is
; , | 1 | ,
Hi ( lllll.l
IIIC"I|.|I I1)
25.0
(50.0)
37.0
(48.0)
..
__ '
(50.0)
50.0
'
26.0
(42.0)
50.0
(50.0)
6.0
24.0
(63.0)
Value of
Sensitive
(Interme-
diate)
Ciop
(Millions)
34.1
(68.3)
287.2
13/2.5,
2.051.8
(3.370.9)
426.7
(358.4)
59.0
(95.4)
324.3
(324.3)
45.6 ,
. . . .
32'j.8
(UbS.I)
'\ ! (11
Y 11 1 1
I.I
.9
.8
7.2
4.1
43.1
53 9
— - —
"~3.~9
1.5
1.0
U.I
3.6
1.1
8.1
9.4
111 1 ions)
/.•: I 1
. 1
1.8
I.C
14.4
8.2
86 2
IO/.8
17.0
7.8
3.0
2.0 '
16.2
7.2
2.2
16.3
IU.U
-------
TABLE 3 (Cont.)
Revised Estimates of Reduction in Economic Uamaije
to Faun Cio|>s, Koiebt Produtls, anJ Ornamentals (.09 >• .10)
1 ' III1
. 1 • .
II 1 1 II 1 1
'-, . .1
•.oybeans
(5) .
soybeans
K)
\ * 1
spinach (f)
spinach (f)
potatoes, ,
i (' '
'pot (it OPS, >
i ice (s)
I HC (s)
tobacco (t )
tobacco (f)
lonialo (fr)
tomato (fr)
wheat (s)
wlic-at (s)
l.il i .1
.09
, | III,' t III S
6.5
5.0
19. 6
4.5
19.6
4.5
I'J.6
4.5
14. i
.9
33.0
4.5
10. C
6.9
In en y
1 . .
.10
I.I.../MH .
9'3
6.4
22.1
22.1
"6.1
22.1
6.1
17.2
2.1
35.3
6.1
22.1
U.I
.inn i !• .ii
,'i ii
lull i,
III (III /
all sens.
legumes
all HI tor.
legumes
all sens.
plants
all inter.
plants
"all sens"."
plants
all inter .
plants
all sens.
plants
all intur.
plants
all sens.
tobacco
all inter.
tobacco
all sens.
tomato
all inter.
plants
alt sens.
plants
alt inter.
wheat
i IJ.iiii.'.ji'
Vl.jl.l U.'.
(f.K.) I-
»•*'•!
L ,1'-' i 1 i-l
*• j i * • • i
i i
.09
| 'nil/. .In ,
1.5
0.0
19.6
4.5
14.6
0.0
14.6
0.0
14.2
0.9
20.0
0.0
14.6
1.9
(IM.'L
'.I Ll. Ml
II 1 U 1 1 U"
is ni'1 Y K
i .i" °l
.10
I'l "/ i.r .
;.3
1.4
22.1
6.1
17.1
1.1
17.1
1 .1 ~
17.2
2.1
30.3
1.1
17. 1
3.1
'
H
Y It l 1
2.8
1.4
2.5
1.6
2.5
1.1
2.5
1.1
3.0
1.2
2.3
I.I
2.5
1.2
"
. i ,i« >H
i il'|l
i, ill 1 1 Ions)
9,945.0
9.945.0
24.0
24.0
1,275.3
1,275.3
928.7
928 7
2.29J.8
2,293.8
914.1
914.1
4,6/7.0
4.6//.0
_
.nl ( i n|i
i >, ,i i •
. ll ,|l U.
•• ( • -
I.-.M .1. )
36.0
(54.0)
50.0
(38.0)
25.0
(50.0)
24.0
(63.0)
9.0
-
(26.0)
44.0
(3M.O)
?4.0
(63.0)
Value of
Sens it ive
( liilyniifi-
(1 1 .1 1 e )
Cl Op
'SMillions;
3,580.2
(5,370.3)
12.0
(9.1)
318.8
(637.6)
222.9
(5135.1)
206.4
-
(596.4)
402.2
(347.4)
I.1P2.5
(2.M46.5)
„
_
t J|
V H I.I
I.I
100.2
75.2
.3
.1
8.0
7.0
5.6
6.4
6.?
- *
7.2
9.3
3.8
28.1
35.4
. ._
•III! ions)
f ': i i
• 1
2UU.4
150 -1
" .6
.2
15.9
14.0
11. 1
12.9
12.4
14.4
18.6
7.f>
50 ?
AI.8
-
-------
Lo r.inn Crops, lurest !Yr><|i,i. u,j UMM'• S
"
19.6
fl.5
19.6
1.5
.
• ™ " "
™ -~
I
I'M ' /
.10
fi, /Mil '.
22.1
G.I "
22. 1
__*:Ll"
.. __
.
.
'"" ^
> ,i, .11 .
\ "
i "i I.H
miii>y
afl iciis
.plants
all inler.
Ptants .
all sens.
plants
aft inter.
Plants
• • •
'i I1' ['.•"(<•
1 \r> li| ljo
('-I'.) '•
• 1 I -
I i 1" |
.09
J pill/.' I.I S
"
_
19. G
4.5
19 6
1.5
-•
("'"' I I--
.. 1 J
."
1.6
" r.;
1.6
-
'
1 ' .
(' .1 II n..,
2,100 ll
2, 900.0
1 .3DO.O
1.300,0
. ,.i i . "ii
. . • i ,.•
, i
h i<< )
?0.0
(2(1.0)
9.0
..
v.iiue of
'.orr, 1 1 ivc
( |nli.JM..«-
MMlf.1)
1 i 'i|i
.ill, Hums)
.
i30 0
(510.0)
117 0
(?/3 0)
. __ _. .
—
• t
i"ii
1 I
i.m u
1-1.5
.
9.3
2.0
1 -1
31.1
"ftos.y
*~ • • "
._
.
ii 1 1 t'.ii' j
i !
1
I,.1! If, 11
ft n
I!1. 1.
-*.'•
r.r
i-? .
l . un .1
-------
Table 4
Growth and Yield fl'tpontn of Plar'j. t>i Oione
Compared with Foliar Injury 3eiponip
t
Pl."t species
. CuUivar (CV.)
i
"Alfalfa.
i cv. Vernal
Bean.
Cv. Pinto
C'jcutrser.
:v. Ohio .Tsuc
Onion,
cv. Spartan Ira
cv. Cherry 3eile
Radisn.
CV. Cherry Jell*
cv Hood
and Cire
Cv. Oar*
cv. Golden Midget
Tobacco.
cv. del t-3
Tobacco,
cv. a«l V-3
Tooacca.
CV. Burley-Jl
Icmata.
CV. H.ll
0. concenlratipn.
ppiti*
O.OS (.)
0.30
0.30
0.30
0.30
1.0
1.0
1.0
1.0
0.05C-)
0.151')
O.i5(*)
3.CS(*>
0.10(*)
0.05 I*)
o.io(-)
0.05(-)
O.IO(»)
Exposure pattern
Number of hours(h)
days(d). i wee«s(«
8h/d. Sd/w, 12w
0.5h/d. I4d
lh/dt 14d
2h/d^ 144
3n/d. Ud
In
4n
in
3n/d, Sd/.. S-
4h
Sh/d. S^w. 3w
8 h/d. Sd/-, 3w
6h/d, 133d
6h/d. 133d
6h/d, 6Jd
6h/d, Wd
acbient: often
X).05PP«(») *«*
O.CS(.)
0.05(.)
0.23(»)
o.:s(-)
8n/d, Sd/«, 4w
3h/d, Ed/w. 4w
2.Sn/d. 3d/«.
2.5 h/d. 3d/w.
Plant gro«ln or yield Foliar tnjurjr
. response. - reduction resoon'.e. ~ increase
) from control Over control
12fr. foliage dry wt; 0
22»». root dry wt ,
11*. leaf dry wl; 22°
14*. tlrm dry wt ;
231. root dry .t.
40». leaf dry wt: 82 s
57J. item dry wt;
65*. root dry wt;
70». leaf dry wl; S3 b
BO*. »to» dry wt;
BJ/. root dry -t;
76*. 1»iC.Jry wt; 90 B
85*. sle^i dry wt;
68», root dry wt;
19», too dry wl; 1'
37». top dry wt; IB*
21». plant dry wl; 2*
48*. plant dry wt; 6*
10**. leaf dry wt; t
SO*', root dry wt;
No significant effect 13
33rr. folUoe dry wt; 80
lltt, root ery wt;
2*. top fresh wt: 8*
. 3?. .root fresn »t;
21.'. top frej1! wt;- 19*
I4». root fneih. wt;
3*. ie«l yteld; 19*
2f, plant freih wt;
5Sf. \ffd yield; 37J
6Sf, plant frvsn wt;
9*, k«rnrt;
42»f . root dry wt;
No significant reductions trace
IS- !••. fruit yield. eiiennv». consio-rjole
32'», too dry wt. anoant o' dr'oliatian
11". root ory wt,
15w 4V« fruit yi»ld; utentive. »lnotl
72*f. too dry -t. cwoletely defoliated
53*r. root dry »t.
Reference
30.7, .83
31
32
82
U
30.73
84
8*
•Ml
I/.ZJ
30. n
10.79
£3
".o * latisncil ly sinnifieint d<"erence '<-
-------
from the National Academy of Sciences ]977 reporc
on Ozone and other Photochemical Oxidants (ref. 4)
5,.] OZONE A.ND OT1IF.R PHOTOCHEMICAL OXIDANTS
O «<*J»IOOIII |K
a «i M (Q>ln>
O Pfw-rwil
O -^(-.. K MI
[10'IUCCI
ft i
I"
III
itO »• BiWH l!»
[•'l(il)UI: .)••! Cnrix'hlmti iK'lwccn llxiill .nul in.uini.il n/inii: I-IIIKTII-
IIMliiin. ll.iscil mi 2-li ,IVCI.IJ;L'I| tl.il.i l.iki-n in lilt 1.111 Aii^do. full-
lonn.1. area. Kcpnnltd mill pcriiussion Iruni I Inly."
-------
UNITED STATES DEPARTMENT OF AGRICULTURE
SCIENCE AND EDUCATION ADMINISTRATION
1224 Gardner Hall, Botany Dept
FEDERAL RESEARCH NORTH CAROL.NA STATE UMVIR.!^
SOUTHERN REG.ON RALE.GH. NORTH CAROLINA 27«3O
September 27, 1978
Subject: Estimate of Economic Benefits Associated with Alternative
Secondary Ozone Standards
To: Mr. Don Lokey
Mr. Harvey Richmond
U. S. Environmental Protection Agency
MD-12
Research Triangle Park, N. C. 27711
I have scanned with interest your development of the above subject
matter. You have made use of data that was generated for this use.
I had hoped to do something like that for the NAS document but time
did not permit.
I have problems with some of your assumptions but you have well stated
these problems and have included comments from many people with whom
you have communicated. Your approach is clearly given, your caveats
are well stated and your discussions with experts are well presented.
I personally have no problems with your presentations.
However, based on observations in field work here at NCSU, I have some
of the same concerns voiced by Dr. Heggestad. I will raise some
questions without really giving you any answers.
1. I question the 0.07 and 0.09 ppm 0_ for 8 hrs when the hourly is
0.08 and 0.10 respectively.
2. Further, if the hourly is 0.08 or 0.10 ppm, what would you expect to
find in terms of numbers of days from Ma/ - September when the 8 hr
average each day would be above say 0.06 ppm?
3. I would tend toward a different ratio for the best and worst case
of yield:injury ratio. The worst would be 1:1 and the best 1:2.
This would not be for leafy crops used for human consumption where
a 10:1 ratio could hold.
4. I would also stress the dangers of extrapolation from short term
acute exposures with injury as the prime response to long term
chronic exposures where harvested yield is the prime concern.
I still like your approach and believe it is a first effort that should
be submitted. At the least, it will make others seriously look at
economic impact.
-------
Page 2
Mr. Don Lokiiv
Mr. Harvey Richmond
I would encourage you Co Look at che paper by Larsen and ,-r/self. Larsen
cook the same data that is in the NAS document and develio-id cnunt Lons
for the same groupings of plants. I had wanted to use the Larson-Heck
equations in the NAS document but the data was not readv in c Lne to
make our NAS deadline. I personally believe these equations are more
realistic than the Heck-Tingey equation. The data is available, if
you want to make use of it at any time.
I appreciate the chance to review your efforts and commend you on the
Walter W. Heck
Research Leader
Southern Region, SEA
WWH/rsnc
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