# Ozone Air Quality Standards: EPA’s Proposed Revisions

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URL: https://www.frixlaw.com/law-library/documents/crs%3AR41062

## Record

- **Collection:** Congressional research report
- **Document type:** CRS Report
- **Published:** December 21, 2010
- **Citation:** R41062

## Text

Ozone Air Quality Standards:
EPA’s Proposed Revisions
name redacted
Specialist in Environmental Policy
December 21, 2010

Congressional Research Service
7-....
www.crs.gov
R41062

CRS Report for Congress
Prepared for Members and Committees of Congress

Ozone Air Quality Standards: EPA’s Proposed Revisions

Summary
On December 8, 2010, the Environmental Protection Agency (EPA) announced that it will delay
issuing revised ambient air quality standards for ozone until July 2011 so that it can consider
further recommendations from an independent panel of scientific advisers. The agency proposed
changes to the National Ambient Air Quality Standards (NAAQS) for ozone on January 19, 2010,
with an expected promulgation date of August 2010. The December announcement marks the
third time that the agency has postponed issuing the revised standards.
NAAQS are standards for outdoor (ambient) air that are intended to protect public health and
welfare from harmful concentrations of pollution. By changing the standard, EPA would be
concluding that protecting public health and welfare requires lower concentrations of ozone
pollution than it previously judged to be safe. Under the January 2010 proposed standards, as
many as 96% of the counties that currently monitor ozone might need to take action to reduce
emissions. The proposal would also, for the first time, set a separate standard for public welfare,
the principal effect of which would be to call attention to the negative effects of ozone on forests
and agricultural productivity.
The ozone standard affects a large percentage of the population: as of September 2010, 119
million people (nearly 40% of the U.S. population) lived in areas classified “nonattainment” for
the primary ozone NAAQS. As a result of the standard’s strengthening, more areas would likely
be affected, and those already considered nonattainment may have to impose more stringent
emission controls.
The proposed revision would lower the primary (health-based) standard from 0.075 parts per
million—75 parts per billion (ppb)—averaged over 8 hours to somewhere in the range of 70 to 60
ppb averaged over the same time. Using the most recent three years of monitoring data, 515
counties (76% of all counties with ozone monitors) would violate the new standard at 70 ppb; 650
counties (96% of those with monitors) would be in nonattainment if the standard is set at 60 ppb.
By comparison, only 85 counties have monitors showing exceedance of the currently
implemented 1997 standard. (The counties that might exceed the proposed standard are shown in
Figure 3 of this report.)
The proposed standards, now expected to be finalized in July 2011, will set in motion a long and
complicated implementation process that has far-reaching impacts. The first step, designation of
nonattainment areas, is expected to take place within a year of the new standards’ promulgation;
the areas so designated would then have 3 to 20 years to reach attainment.
The proposed standards raise a number of issues, including whether they should lead to stronger
federal controls on the sources that contribute to ozone pollution. Current federal standards for
cars, trucks, nonroad vehicles and engines, power plants, and other stationary pollution sources
are not strong enough to bring many areas into attainment, thus requiring local pollution control
measures in many cases. EPA, the states, and Congress may also wish to consider whether the
current monitoring network is adequate to detect violations of a more stringent standard. Only
675 of the nation’s 3,000 counties have ozone monitors in place.
This report discusses the standard-setting process, the specifics of the new standard, and issues
raised by the Administrator’s choice; and it describes the steps that will follow EPA’s
promulgation.

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Ozone Air Quality Standards: EPA’s Proposed Revisions

Contents
Introduction...................................................................................................................................... 1
What Are NAAQS? ......................................................................................................................... 1
The NAAQS Process ....................................................................................................................... 3
The Ozone Standard......................................................................................................................... 3
The Primary Standard ................................................................................................................ 3
The Secondary Standard ............................................................................................................ 7
Controlling Ozone Pollution ............................................................................................................ 9
Costs and Benefits of Control .......................................................................................................... 9
Issues.............................................................................................................................................. 10

Figures
Figure 1. Counties with Monitors Violating the 1997 Eight-Hour Ozone Standard
(0.08 parts per million) ................................................................................................................. 5
Figure 2. Counties with Monitors Violating the Eight-Hour Ozone Standard Promulgated
in 2008 (0.075 parts per million) .................................................................................................. 6
Figure 3. Counties With Monitors Violating Proposed Primary 8-hour Ground-level
Ozone Standards, 0.060-0.070 parts per million .......................................................................... 7
Figure 4. Counties With Monitors Violating Proposed Secondary Seasonal Ground-Level
Ozone Standards, 7–15 parts per million-hours............................................................................ 8

Contacts
Author Contact Information........................................................................................................... 12

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Ozone Air Quality Standards: EPA’s Proposed Revisions

Introduction
On January 19, 2010, the Environmental Protection Agency (EPA) proposed revisions to the
National Ambient Air Quality Standards (NAAQS) for ozone.1 Because they have widespread
implications for public health and for the pollution control measures that will be imposed on
sectors of the economy, the revisions have stirred congressional interest and caused a variety of
reactions among state and local officials. EPA held three public hearings (in Arlington, VA,
Houston, TX, and Sacramento, CA) during the first week of February 2010, and accepted public
comments in writing until March 22. The agency received more than 5,000 unique comments.
Final standards were expected to be issued by the end of August 2010, but EPA has delayed
promulgation, first to October, then to December, and now to July 2011. The delays have allowed
the agency to analyze the information it received during the public comment period. Having done
so, the agency says that it intends to seek additional advice from the Clean Air Scientific
Advisory Committee (CASAC), a panel of outside experts who review agency decision-making
regarding the setting of NAAQS. Specifically, the agency intends to take the following steps:
During December 2010 and January 2011, EPA intends to prepare a set of questions for
CASAC and provide them for CASAC’s review. The questions are expected to request
additional advice focused on the scientific evidence and other information before the
Administrator. EPA anticipates that CASAC will hold a public meeting in February 2011 to
discuss their response, and anticipates that CASAC will provide its additional advice to the
Agency by letter shortly thereafter. The CASAC process includes an opportunity for the
public to submit comments to CASAC and EPA. EPA intends to issue a final decision on the
reconsideration by July 29, 2011.2

The final decision will be subject to interagency review under Executive Order No. 12866 before
being promulgated.
This report provides background on NAAQS, the process used to establish them, the pre-existing
ozone standards, and EPA’s proposed revisions, as well as information regarding the revisions’
potential effects.

What Are NAAQS?
As defined in Section 109 of the Clean Air Act, NAAQS are standards that apply to ambient
(outdoor) air. The act directs EPA to set both primary and secondary standards. Primary NAAQS
are standards, “the attainment and maintenance of which in the judgment of the [EPA]
Administrator ... are requisite to protect the public health,” with “an adequate margin of safety.”
Secondary NAAQS are standards necessary to protect public welfare, a broad term that includes
damage to crops, vegetation, property, building materials, etc.3

1

75 Federal Register 2938.
Declaration of Regina McCarthy, Assistant Administrator for Air and Radiation, Environmental Protection Agency,
December 8, 2010, State of Mississippi v. EPA, Document 1281979, D.C. Cir. No. 08-1200.
3
The Clean Air Act’s definition of welfare is found in Section 302(h) of the act (42 U.S.C. 7602).
2

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NAAQS are at the core of the Clean Air Act, even though they do not directly regulate emissions.
In essence, they are standards that define what EPA considers to be clean air. Once a NAAQS has
been set, the agency, using monitoring data and other information submitted by the states,
identifies areas that exceed the standard and must, therefore, reduce pollutant concentrations to
achieve it. After these “nonattainment” areas are identified, state and local governments have up
to three years to produce State Implementation Plans which outline the measures they will
implement to reduce the pollution levels and attain the standards. Depending on the severity of
the pollution, ozone nonattainment areas have anywhere from 3 to 20 years to actually attain the
standard.
EPA also acts to control many of the NAAQS pollutants wherever they are emitted, through
national standards for products that emit them (particularly mobile sources, such as automobiles)
and emission standards for new stationary sources, such as power plants. Thus, establishment or
revision of a NAAQS sets in motion a long and complicated implementation process that has farreaching impacts for public health, for sources of pollution in numerous economic sectors, and for
states and local governments.
The pollutants to which NAAQS apply are generally referred to as “criteria” pollutants. The act
defines them as pollutants that “endanger public health or welfare,” and whose presence in
ambient air “results from numerous or diverse mobile or stationary sources.”4 Six pollutants are
currently identified as criteria pollutants: ozone, particulates, carbon monoxide, sulfur dioxide,
nitrogen oxides, and lead. The EPA Administrator can add to this list if she determines that
additional pollutants meet the act’s criteria, or delete them if she concludes that they no longer do
so.
The act requires the agency to review each NAAQS every five years. That schedule is rarely met,
but it often triggers lawsuits that force the agency to undertake a review. In the case of ozone, the
American Lung Association filed suit over EPA’s failure to complete a review in 2003, and a
consent decree established a schedule under which the Bush Administration’s EPA promulgated
revisions to the NAAQS in March 2008.5 Numerous parties petitioned the courts for a review of
that standard,6 and, with the change of Administrations, EPA itself concluded that it had concerns
whether the 2008 standards “satisfy the requirements of the Clean Air Act.” Thus, in September
2009, the agency suspended implementation of the 2008 standards and set a schedule for their
review under which the January 2010 proposal was released. EPA is also in the process of
reviewing several other NAAQS. For more information, see the “Air Quality Standards” section
of CRS Report R40145, Clean Air Issues in the 111th Congress.

4
Authority to establish NAAQS comes from both Sections 108 and 109 of the act; this definition of criteria pollutants
is found in Section 108. The authority and procedures for controlling the sources of criteria pollutants are found
throughout Titles I, II, and IV of the act. Pollutants that are less widely emitted are generally classified as “hazardous
air pollutants” and are regulated under a different section of the act (Section 112).
5
The schedule was set by a consent decree that settled a lawsuit filed by the American Lung Association (American
Lung Association v. Leavitt, D.D.C., No. 03-778, modified consent decree approved 12/16/04). EPA agreed that it
would propose whether to retain or revise the ozone standard by June 20, 2007, and take final action by March 12,
2008.
6
Mississippi v. EPA, D.C. Cir., No. 08-1200, notice filed 9/16/09.

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The NAAQS Process
Reviewing an existing NAAQS is generally a long process. To begin the process, EPA scientists
review the scientific literature published since the last NAAQS revision, and summarize it in a
report known as a Criteria Document or Integrated Science Assessment. The review that
culminated in the 2008 ozone revision identified 1,700 scientific studies on topics as wideranging as the physics and chemistry of ozone in the atmosphere; environmental concentrations,
patterns, and exposure; dosimetry and animal-to-human extrapolation; toxicology; interactions
with co-occurring pollutants; controlled human exposure studies; epidemiology; effects on
vegetation and ecosystems; effects on UVB exposures and climate; and effects on man-made
materials. A second document that EPA prepares, the Staff Paper or Policy Assessment,
summarizes the information compiled in the Criteria Document and provides the Administrator
with options regarding the indicators, averaging times, statistical form, and numerical level
(concentration) of the NAAQS.
To ensure that these reviews meet the highest scientific standards, the 1977 amendments to the
Clean Air Act required the Administrator to appoint an independent Clean Air Scientific Advisory
Committee (CASAC). CASAC has seven members, largely from academia and from private
research institutions. In conducting NAAQS reviews, their expertise is supplemented by panels of
the nation’s leading experts on the health and environmental effects of the specific pollutants that
are under review. These panels can be rather large. The review panel for the 2008 ozone standard,
for example, had 23 members. CASAC and the public make suggestions regarding the
membership of the panels on specific pollutants, with the final selections made by EPA. The
panels review the agency’s work during NAAQS-setting and NAAQS-revision, rather than
conducting their own independent reviews.

The Ozone Standard
The ozone standard affects a larger percentage of the population than any of the other NAAQS.
As of September 2010, 39% of the U.S. population lived in areas designated nonattainment under
the 1997 standard for ozone, 119 million people in all.7 Since the standard has been strengthened
as a result of a review completed in 2008 and the Administrator is now proposing a further
strengthening, more areas will be affected, and those already considered nonattainment may have
to impose more stringent emission controls.

The Primary Standard
The primary (health-based) standard promulgated in 1997 was set at 0.08 parts per million (ppm),
averaged over an 8-hour period. Allowing for rounding, EPA considered areas with readings as
high as 0.084 ppm (84 parts per billion) to have attained the standard.
The review completed in 2008 found evidence of health effects, including mortality, at levels of
exposure below the 0.08 ppm standard. As a result, both EPA staff and CASAC recommended
7

For information on the nonattainment areas, including maps and population data, see EPA’s “Green Book” at
http://www.epa.gov/oar/oaqps/greenbk/index.html.

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strengthening the standard. According to CASAC, “There is no scientific justification for
retaining the current [0.08 ppm] primary 8-hr NAAQS.”8 The panel unanimously recommended a
range of 0.060 to 0.070 ppm (60 to 70 parts per billion) for the primary 8-hour standard.
EPA staff also recommended strengthening the standard, in wording not quite so direct. The staff
stated, “The overall body of evidence on ozone health effects clearly calls into question the
adequacy of the current standard.” They recommended “considering a standard level within the
range of somewhat below 0.080 parts per million (ppm) to 0.060 ppm.”9
Based on these recommendations, and his own judgment regarding the strength of the science,
Stephen Johnson, the Bush Administration’s last EPA Administrator, chose to finalize the standard
at 0.075 ppm (75 parts per billion).10 That revision has not yet been implemented, however: the
designation of nonattainment areas has not been completed, and the Obama Administration’s EPA
announced in September 2009 that it would undertake a further review of the NAAQS before
completing the designations.11
As shown in Figure 1, using 2004-2006 data, 85 counties had monitors showing violation of the
old 0.08 ppm primary standard. Figure 2 shows what happens when the standard is strengthened
to 0.075 ppm (75 ppb), again using 2004-2006 data: under the 0.075 ppm standard, 345 counties,
more than four times as many, showed violations. Figure 3, using more recent monitoring data,
shows the number of counties that would exceed a standard in the range of 0.060 to 0.070 ppm.
At 0.070 ppm, 515 counties (76% of those with monitors) exceeded the standard. At 0.060 ppm,
650 counties—virtually every county with a monitor—exceeded the proposed standard.
EPA notes that nonattainment designations will not actually be made until at least 2011, and will
likely use data for the period 2008-2010. Given the trend toward cleaner air in recent years, and
regulations on both mobile and stationary sources that have taken effect in the intervening years,
the agency expects the number of counties exceeding the standard to be less than indicated by
these projections. Nevertheless, because a strengthening of the standard will result in some
(perhaps a substantial number of) additional areas being designated nonattainment, and will mean
that current nonattainment areas may have to adopt additional pollution control measures in order
to reach attainment, numerous industry groups were reported to have challenged the scientific
conclusions in meetings with Bush Administration officials before the 2008 review was
completed.12 Some of the same concerns have surfaced in the public comment period on the 2010
revision.13 Members of Congress have been among those commenting on EPA’s proposed
8
Letter of Rogene Henderson, Chair, Clean Air Scientific Advisory Committee, to Hon. Stephen L. Johnson, EPA
Administrator, October 24, 2006, available at http://yosemite.epa.gov/sab/sabproduct.nsf/
AB290E0DB8B72A33852572120055858F/$File/casac-07-001.pdf.
9
“Review of National Ambient Air Quality Standards for Ozone Final Staff Paper, Human Exposure and Risk
Assessments and Environmental Report,” Fact Sheet, at http://www.epa.gov/ttn/naaqs/standards/ozone/data/
2007_01_finalsp_factsheet.pdf.
10
All of EPA’s references to the standard are expressed as parts per million (e.g., 0.075 ppm), but many references in
the press convert this to a more readable parts per billion (i.e., 75 parts per billion). In order to avoid confusion when
quoting from EPA sources, this report generally uses the more cumbersome parts-per-million form.
11
See “Fact Sheet: EPA to Reconsider Ozone Pollution Standards,” September 16, 2009, at http://www.epa.gov/
groundlevelozone/pdfs/O3_Reconsideration_FACT%20SHEET_091609.pdf.
12
“EPA Target of Intensive Lobbying Over Forthcoming Ozone Decision,” Daily Environment Report, March 10,
2008, p. A-3, and “Energy Industry Presents Case to Preserve Existing Air Quality Standard for Ozone,” Daily
Environment Report, February 6, 2008, p. A-9.
13
See, for example, “Chemical, Oil, Gas Industries Criticize EPA Ozone Proposal at Hearing in Houston,” Daily
(continued...)

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revision: on August 6, 2010, a bipartisan group of seven Senators wrote the EPA Administrator,
asking her to maintain the current (2008) standards, noting that “the Agency has not presented
new data or evidence to justify its course of action.”14
Figure 1. Counties with Monitors Violating the 1997 Eight-Hour Ozone Standard
(0.08 parts per million)
(Based on 2004-2006 Air Quality Data)

Source: U.S. EPA.
Notes: (1) 85 monitored counties violate. (2) Monitored air quality data can be obtained from the AQS system
at http://www.epa.gov/ttn/airsaqa/. (3) The 1997 national ambient air quality standard (NAAQS) for ozone of
0.08 ppm is effectively expressed as 0.084 ppm when data handling conventions are applied.

(...continued)
Environment Report, February 4, 2010, p. A-5.
14
Letter of Senator George V. Voinovich et al., to EPA Administrator Lisa Jackson, August 6, 2010.

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Figure 2. Counties with Monitors Violating the Eight-Hour Ozone Standard
Promulgated in 2008 (0.075 parts per million)
(Based on 2004-2006 Air Quality Data)

Source: U.S. EPA.
Note: Estimates were based on the most recent data at the time of promulgation (2004-2006). 345 monitored
counties violated the 2008 8-hour ozone standard of 0.075 parts per million (ppm), based on those data.
Monitored air quality data can be obtained from the AQS system at http://www.epa.gov/ttn/airsaqs/

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Figure 3. Counties With Monitors Violating Proposed Primary 8-hour
Ground-level Ozone Standards, 0.060-0.070 parts per million
(Based on 2006–2008 Air Quality Data)

Source: U.S. EPA
Notes: (1) No monitored counties outside the continental U.S. violate. (2) EPA is proposing to determine
compliance with a revised primary ozone standard by rounding the three-year average to three decimal places.

The Secondary Standard
As part of the review completed in 2008, EPA also assessed the secondary (public welfare)
NAAQS for ozone, which was identical to the previous 0.08 ppm primary standard. Ozone affects
both tree growth and crop yields, and the damage from exposure is cumulative over the growing
season. In order to provide protection against ozone’s adverse impacts, EPA staff recommended a
new seasonal (3-month) average for the secondary standard that would cumulate hourly ozone
exposures for the daily 12-hour daylight window (termed a “W126 index”). The staff
recommended a standard in a range of 7-21 parts per million-hours (ppm-hours). CASAC’s ozone
panel agreed unanimously that the form of the secondary standard should be changed as the staff
suggested, but it did not agree that the upper bound of the range should be as high as 21 ppmhours, suggesting that the upper bound be no higher than 15 ppm-hours.15 The Administrator’s
June 2007 proposal was in line with the staff recommendation, 7-21 ppm-hours, but his final
March 2008 choice was to duplicate the primary standard he promulgated at that time. He set a
15
Letter of Rogene Henderson, Chair, Clean Air Scientific Advisory Committee, to Hon. Stephen L. Johnson, EPA
Administrator, March 26, 2007, p. 3, available at http://yosemite.epa.gov/sab/sabproduct.nsf/
FE915E916333D776852572AC007397B5/$File/casac-07-002.pdf.

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secondary standard at 0.075 ppm averaged over 8 hours, rejecting the advice of both CASAC and
his staff.
Figure 4. Counties With Monitors Violating Proposed Secondary Seasonal GroundLevel Ozone Standards, 7–15 parts per million-hours
(Based on 2006 –2008 Air Quality Data)

Source: U.S. EPA
Notes: No monitored counties outside the continental U.S. violate.

The secondary standard carries no deadline for attainment and has never been the subject of
penalties or sanctions for areas that failed to meet it (unless they also violated a primary
standard), but there was substantial disagreement between the Bush Administration EPA and the
White House over the form in which this standard should be set. (For a discussion, see archived
CRS Report RL34057, Ozone Air Quality Standards: EPA’s March 2008 Revision.)
The new (January 2010) proposal would adopt the W126 index and would set the secondary
standard at 7-15 ppm-hours, in line with CASAC’s recommendations. As shown in Figure 4,
nonattainment with the proposed secondary standard could be widespread: based on the latest
available (2006-2008) data at the time of proposal, 196 counties would be nonattainment if the
secondary standard were set at 15 ppm-hours, and 579 counties (86% of all counties with
monitors) would be nonattainment under a 7 ppm-hours standard. As discussed further below,
however, few rural counties have ozone monitors, so the true extent of nonattainment with the
secondary standard is unknowable. EPA has proposed additional ozone monitoring requirements

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for both urban and non-urban areas and expects to issue a final monitoring rule in coordination
with the final ozone standards.16

Controlling Ozone Pollution
Controlling ozone pollution is more complicated than controlling many other pollutants, because
ozone is not emitted directly by pollution sources. Rather, it forms in the atmosphere when
volatile organic compounds (VOCs) react with nitrogen oxides (NOx) in the presence of sunlight.
The ozone concentration is as dependent on the temperature and amount of sunshine as it is on
the presence of the precursor gases. In general, ozone is a summertime pollutant. Other factors
being equal, a cool, cloudy summer will produce fewer high ozone readings than a warm, sunny
summer.
There are also complicated reactions that affect ozone formation. In general, lower emissions lead
to less ozone, particularly lower emissions of VOCs. But under some conditions, higher
emissions of NOx lead to lower ozone readings. This makes modeling ozone air quality and
predicting attainment more difficult and contentious than the modeling of other air pollutants.
Most stationary and mobile sources are considered to be contributors to ozone pollution. Thus,
there are literally hundreds of millions of sources of the pollutants of concern and control
strategies require implementation of a wide array of measures. Among the sources of VOCs are
motor vehicles (about 40% of total emissions), industrial processes, particularly the chemical and
petroleum industries, and any use of paints, coatings, and solvents (about 40% for these sources
combined). Service stations, pesticide application, dry cleaning, fuel combustion, and open
burning are other significant sources of VOCs. Nitrogen oxides come overwhelmingly from
motor vehicles and fuel combustion by electric utilities and other industrial sources.

Costs and Benefits of Control
EPA is prohibited from taking cost into account in setting NAAQS, but to comply with an
executive order (E.O. 12866) and guidance from the Office of Management and Budget, the
agency generally produces a Regulatory Impact Analysis (RIA) analyzing in detail the costs and
benefits of new or revised NAAQS standards. The agency produced an RIA for its 2008 ozone
NAAQS, and it released an 89-page supplement to that RIA in conjunction with the January 2010
proposal. The major conclusions regarding benefits and costs were also included in a Fact Sheet
posted on the agency’s website.17 The analysis shows a wide range of estimates for benefits, from
a low of $13 billion annually to a high of $100 billion annually in 2020. EPA estimates of the
costs of implementing the standard also range widely, from $19 billion to $90 billion annually in
2020.
The public health benefits of setting a more stringent ozone standard are the monetized value of
such effects as fewer premature deaths, fewer hospital admissions, fewer emergency room visits,
16

See “Fact Sheet: Proposal to Revise the National Ambient Air Quality Standards for Ozone,” p. 4, at
http://www.epa.gov/air/ozonepollution/pdfs/fs20100106std.pdf.
17
The supplement and the Fact Sheet can be accessed at http://www.epa.gov/air/ozonepollution/actions.html#jan10s.

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fewer asthma attacks, less time lost at work and school, and fewer restricted activity days.18 The
Fact Sheet accompanying the proposed standards states that the benefits of a 0.070 ppm primary
standard would include the avoidance of 1,500 to 4,300 premature deaths annually in 2020,
whereas the more stringent 0.060 ppm standard would avoid 4,000 to 12,000 premature deaths
annually.19 Other benefits in 2020 would include preventing the following, annually20:
•

880 to 2,200 cases of chronic bronchitis

•

2,200 to 5,300 nonfatal heart attacks

•

6,700 to 21,000 hospital and emergency room visits

•

2,100 to 5,300 cases of acute bronchitis

•

44,000 to 111,000 cases of upper and lower respiratory symptoms

•

23,000 to 58,000 cases of aggravated asthma

•

770,000 to 2.5 million days when people miss work or school

•

2.6 million to 8.1 million days when people must restrict their activities.

In the supplement, the agency notes that “there are significant uncertainties in both cost and
benefit estimates for the full range of standard alternatives.” Among the uncertainties are
unquantified benefits (the effects of reduced ozone on forest health and agricultural productivity,
for example) and unquantified disbenefits (reduced screening of UVB radiation and reduced
nitrogen fertilization of forests and cropland). The benefits will also vary, depending on which of
the precursor pollutants nonattainment areas choose to control.
The RIA also states, “Of critical importance to understanding these estimates of future costs and
benefits is that they are not intended to be forecasts of the actual costs and benefits of
implementing revised standards.”21 If past experience is any guide, this is likely to mean that
costs will not be as great as they are projected to be. In the agency’s words, “Technological
advances over time will tend to increase the economic feasibility of reducing emissions, and will
tend to reduce the costs of reducing emissions.”22 Benefits, meanwhile, will remain difficult to
quantify, in part because of the difficulty of quantifying and valuing lives lost prematurely and
other adverse health effects due to exposure to pollution.

Issues
The major issues raised by the proposed standards concern whether the Administrator has made
appropriate choices (i.e., whether her choices for the primary and secondary standards are backed
by the scientific studies). Unlike the choices made by Administrator Johnson in 2008, both the
18
For a full discussion of these variables and their monetized values, see Chapter 6 of the RIA at http://www.epa.gov/
ttn/ecas/regdata/RIAs/6-ozoneriachapter6.pdf.
19
“Fact Sheet: Supplement to the Regulatory Impact Analysis for Ozone,” at http://www.epa.gov/air/ozonepollution/
pdfs/fs20100106ria.pdf.
20
In each case, the low end of the range represents EPA’s estimate of the benefit from a 0.070 ppm standard; the high
end of the range represents the benefit of a 0.060 ppm standard.
21
Supplement to the RIA for Ozone, p. S-9.
22
Ibid., p. S-12.

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primary and secondary standards proposed by Administrator Jackson reflect the range of values
and the statistical form recommended by the agency’s independent science advisers, CASAC.
Other issues have been raised as affected industries, state environmental agencies, public interest
and environmental groups, and Members of Congress review what EPA has proposed, including
the potential impacts of the new standards on public health and on the economy. In looking at
potential impacts, EPA projected air quality to the year 2020, incorporating the expected
reductions in emissions from a slew of federal regulations, including the Clean Air Interstate Rule
(CAIR), the Clean Air Mercury Rule, the Clean Air Visibility Rule, the Tier 2 auto and light truck
emission standards, several rules affecting diesel engines, and some state and local measures.
Even with these controls, the agency projects that 99 counties in 19 states (counties that include
some of the nation’s biggest cities) would violate the 70 ppb standard in 2020. If the final
standard is set at 60 ppb, 451 counties in 44 states are projected to be in nonattainment.23
Furthermore, most nonattainment areas will not be given until 2020 to attain the standards: for
most, the deadline will likely be 2015 or 2018 (based on the degree to which pollutant
concentrations exceed the new standard). This suggests a mismatch between the full impact of
federal regulations on specific categories of emission sources and the requirement that local areas
demonstrate attainment. This mismatch could support a case for stronger federal controls on the
sources of ozone precursors or a reexamination of the attainment deadlines.
Another issue arises from a close inspection of EPA’s maps: whether the current monitoring
network is adequate to detect violations of a more stringent standard. Only 675 of the nation’s
3,000 counties have ozone monitors in place. With as many as 650 of them (96%) showing
violations of the most stringent proposed standard, using current data, how confident is the
agency that the 2,350 counties without monitors would all be in attainment? The current monitors
are generally found in urban areas, because of the larger population potentially affected, and
because most of the sources of ozone precursor emissions are located in such areas. But, as noted
earlier, ozone is not emitted directly by polluters. It forms in the atmosphere downwind of
emission sources. Thus, rural areas can have high ozone concentrations, unless they are located a
substantial distance from any urban area. In addition to the potential health impacts of ozone in
rural areas, the new form of the secondary NAAQS proposed by EPA suggests a need for
additional monitoring in rural areas to detect impacts on forests and agricultural production.
The agency has, in a separate rulemaking, proposed changing the minimum monitoring
requirements for both urban and non-urban areas.24 That proposal would require that each state
operate at least three ozone monitors in non-urban areas. It would also require at least one ozone
monitor in each urban area with a population between 50,000 and 350,000.

23

For a map showing the 2020 projections, see map 4 in EPA’s briefing materials at http://www.epa.gov/air/
ozonepollution/pdfs/20100104maps.pdf.
24
74 Federal Register 34525, July 16, 2009.

Congressional Research Service

11

Ozone Air Quality Standards: EPA’s Proposed Revisions

Author Contact Information
(name redacted)
Specialist in Environmental Policy
[redacted]@crs.loc.gov, 7-....

Congressional Research Service

12

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Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/crs%3AR41062. Public record. Not legal advice.