Order Code RL33254
CRS Report for Congress
Received through the CRS Web
Air Quality: EPA’s Proposed Changes to the
Particulate Matter (PM) Standard
January 26, 2006
Robert Esworthy and James E. McCarthy
Specialists in Environmental Policy
Resources, Science, and Industry Division
Congressional Research Service ˜ The Library of Congress

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Air Quality: EPA’s Proposed Changes to the
Particulate Matter (PM) Standard
Summary
On December 20, 2005, EPA Administrator Stephen Johnson signed a proposed
revision to the National Ambient Air Quality Standards (NAAQS) for particulate
matter (PM). In developing the revision, EPA reviewed 2,000 scientific studies and
found associations between particulates in ambient air and numerous significant
health problems, including aggravated asthma, chronic bronchitis, reduced lung
function, irregular heart beat, heart attacks, and premature death in people with heart
or lung disease. In the nine cities EPA analyzed, particulates would cause an
estimated 4,729 premature deaths unless current standards are strengthened,
according to agency data.
The proposal would strengthen the existing standard for “fine” particulate matter
2.5 micrometers or less in diameter (PM ) and for larger, but still inhalable, coarse
2.5
particles (PM
). The existing PM standard promulgated in 1997 is only now
10-2.5
beginning to be implemented. The proposal would cut almost in half the allowable
concentration of PM in the air, averaged over 24-hour periods, from 65 micrograms
2.5
per cubic meter (µg/m3) to 35 µg/m3. Eighty-eight million people live in the 208
counties designated as “nonattainment” areas for the current PM NAAQS. The
2.5
proposal is expected to nearly double the number of counties where monitored PM
pollution exceeds the standard. The proposal would eliminate some, but not most, of
the premature mortality. Data compiled by the American Lung Association from
EPA risk assessments indicate the proposed standard would eliminate only 22% of
estimated PM -related premature deaths in the nine cities studied.
2.5
In addition to the 24-hour standard for PM , an annual PM NAAQS
2.5
2.5
addresses human health effects from chronic exposures to the pollutants. The
Administrator proposed to leave the annual standard unchanged at 15 µg/m3, counter
to the recommendations of the Clean Air Scientific Advisory Committee (CASAC),
an independent scientific body that advises the Administrator. CASAC recommended
that this standard be reduced to a range of 13 to 14 µg/m,3 a step that might have
required more stringent controls in additional nonattainment areas. The December
20 proposal also would set a 24-hour standard for slightly larger, but still inhalable,
particles in the range of 10 to 2.5 micrometers (PM
). The Administrator
10-2.5
proposes to focus this standard on urban, industrial, and construction sources,
excluding any mix of particles “dominated by rural windblown dust and soils and PM
generated by agricultural and mining sources.”
In addition to the divergence from the CASAC’s recommendation, several
elements of the proposed PM standard may prove controversial, including the
exclusion of rural sources from the coarse particle standard. Some may also question
the EPA’s strengthening of the standard for all fine particles, without distinguishing
their source or chemical composition. Establishment of PM NAAQS in 1997 proved
controversial and included extensive Congressional oversight. Congress may conduct
oversight of the December 2005 proposal, given its potential for public health and
economic impacts. Under a consent agreement, the Administrator is to promulgate
final revisions to the standard by September 27, 2006. This report will be updated.

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Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
EPA’s Proposed Changes to the PM NAAQS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Alternative PM Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Potential Impacts of More Stringent PM Standards . . . . . . . . . . . . . . . . . . . . . . . . 6
Health Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Impacts of NAAQS Implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Reaction to the Proposed PM NAAQS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Congressional Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
List of Figures
Figure 1. Number of Premature Deaths in Nine U.S. Cities, Estimated
by the American Lung Association for Alternative PM NAAQS . . . . . . . . 8
2.5
List of Tables
Table 1. Current, Proposed, and Alternative
PM Primary (Health) NAAQS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.5
Table 2. Counties with Monitors Projected To Be in Nonattainment for
Current, Proposed, and Alternative PM NAAQS . . . . . . . . . . . . . . . . . . . 10
2.5

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Air Quality: EPA’s Proposed Changes to the
Particulate Matter (PM) Standard
Introduction
To provide increased protection against potential health effects associated with
short- and long-term exposure to particulate matter (including chronic respiratory
disease and premature mortality), the Environmental Protection Agency (EPA)
announced a proposal to change the National Ambient Air Quality Standards
(NAAQS)1 for particulate matter (PM) on December 20, 2005 (71 Federal Register
2620, January 17, 2006). The proposal includes changes to standards for fine and
coarse particles and is expected to generate controversy and national debate, as well
as oversight in Congress, as did the previous changes leading up to the existing PM
standard promulgated in 1997. By consent agreement,2 EPA is to finalize its decision
regarding the PM NAAQS by September 27, 2006.
The proposal is the culmination of EPA’s statutorily required3 review of the
NAAQS and the scientific criteria for setting the standards, which the agency
initiated not long after their 1997 promulgation. Based on its review and analysis of
numerous scientific studies available between 1997 and 2002, and on determinations
made by the Administrator, EPA’s proposal would tighten the current standards
primarily by lowering the daily (24-hour) standard for fine particles smaller than 2.5
microns (PM ). The proposal would also modify the standards for inhalable coarse
2.5
particles smaller than 10 microns but larger than 2.5 microns (PM
). Several
10-2.5
public interest groups and scientists, including an EPA independent advisory
committee, advocated tightening the standards further than proposed. Others contend
that data do not support the need for stricter standards or, in some cases, the 1997
standards.
EPA has estimated that current air quality regulations for reducing PM will
annually prevent “tens of thousands of premature deaths and reduce hospitalizations
for cardiovascular and respiratory illness by tens of thousands more...” resulting in
$100’s of billions in benefits.4 Although EPA has not yet released a regulatory
1 Sections 108-109 of the Clean Air Act (CAA).
2 Consent Agreement, July 2003, C.A. No. 03-778 (ESH). American Lung Association, et
al. v. EPA et al, U.S. District Court for the District of Columbia, as modified.
3 Section 109(d)(1)) of the CAA.
4 EPA Press release: EPA Particulate Matter Research Report Released, September 9, 2004
[http://www.epa.gov/pmresearch/pm_research_accomplishments/].

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CRS-2
impact analysis (RIA) assessing the costs and benefits of its PM NAAQS proposal,5
preliminary estimates of risk reductions and areas affected by EPA and others suggest
the changes will add further similar benefits. On the other hand, tighter standards
will impose additional compliance requirements on communities, states, industry,
and others, at what some stakeholders contend will be a substantial economic cost.
At the time of the 1997 promulgation, EPA estimated the costs to partially attain the
1997 PM standard by 2010 at $8.6 billion annually,6 whereas industry estimates
2.5
were several times higher.
This report summarizes EPA’s proposed changes to the PM NAAQS and the
range of alternative NAAQS recommended by staff and the independent advisory
committee, followed by highlights of potential issues and concerns associated with
the proposal and other PM NAAQS alternatives more stringent than the current
standards. For a detailed discussion of the NAAQS process, see CRS Report 97-722
ENR, Air Quality Standards: The Decisionmaking Process, by John E. Blodgett and
Larry B. Parker; for more information on the implementation of the current PM2.5
NAAQS promulgated in 1997, see CRS Report RL32431, Particulate Matter
(PM ): National Ambient Air Quality Standards (NAAQS) Implementation, by
2.5
Robert Esworthy.
EPA’s Proposed Changes to the PM NAAQS
Under Sections 108-109 of the Clean Air Act (CAA), EPA sets NAAQS for
pollutants whose emissions “may reasonably be anticipated to endanger public health
(primary standards) or welfare (secondary)” and “the presence of which in the
ambient air results from numerous or diverse mobile or stationary sources” (42
U.S.C. 7408(a)(1)).7 EPA’s 1997 revisions to the PM NAAQS (62 Federal Register
38652-38896, July 18, 1997) revised the standards established in 19878 that focused
on particles smaller than 10 microns (PM or coarse particles) and introduced
10
standards for “fine” particles smaller than 2.5 microns (PM ) for the first time.
2.5
The current primary (health protection) NAAQS for both PM and PM
2.5
10
include an annual and a daily (24-hour) limit. To attain the annual standard, the
three-year average of the weighted annual arithmetic mean PM concentration at each
5 The results of analyses that EPA conducted in the process of developing a regulatory
impacts analysis (RIA) to accompany the proposed PM NAAQS are summarized in EPA
White Paper Preliminary Analyses of Proposed PM2.5 NAAQS Alternatives (Office of Air
Quality Planning and Standards Office of Air and Radiation, December 21, 2005), which
can be accessed at [http://www.epa.gov/air/particles/pdfs/whitepaper20051220.pdf].
6 EPA, Regulatory Impact Analysis for the Particulate Matter and Ozone National Ambient
Air Quality Standards and Proposed Regional Haze Rule, July 1997, p. ES-18. Available
at [http://www.epa.gov/ttn/oarpg/naaqsfin/ria.html]. Table 13-1.
7 EPA has promulgated NAAQS for six principal pollutants classified by the agency as
“criteria pollutants”: sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO),
ozone, lead, and particulate matter (PM).
8 PM NAAQS were promulgated in 1987 (52 Federal Register 24640, July 1, 1987).
10

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CRS-3
monitor within an area must not exceed the maximum limit set by the agency. The
24-hour standards are a concentration-based percentile form, indicating the percent
of the time that a monitoring station can exceed the standard. For example, a 99th
percentile 24-hour standard indicates that a monitoring station can exceed the
standard 1% of the time during the year. For PM and PM , the secondary NAAQS,
2.5
10
which are set at a level “requisite to protect the public welfare” (42 U.S.C.
7409(b)(2)),9 are the same as the primary standards.
As proposed, the PM and PM standards would be as follows:
2.5
10
! PM : strengthen the daily standard, which currently allows no more
2.5
than 65 micrograms per cubic meter (µg/m3), by setting a new lower
limit of 35 µg/m3, based on the current three-year average of the 98th
percentile of 24-hour PM concentrations.
2.5
! PM : replace the current particle size indicator of PM with a range
10
10
of 10 to 2.5 micrometers (PM
), referred to as inhalable (or
10-2.5
thoracic) coarse particles; set a PM
daily standard of 70 µg/m3
10-2.5
rather than the current PM daily standard of 150 µg/m3; narrow the
10
focus of the PM
standard on “urban and industrial” sources, and
10-2.5
exclude particles typical to rural areas, including “windblown dust
and soils and PM generated by agricultural and mining sources”;
eliminate the current annual maximum concentration standard for
PM (50 µg/m3) and do not propose an annual standard for PM
10
10-
.10
2.5
The proposal to change the indicator of the standard for coarse particles is in
response to a 1999 U.S. Court of Appeals for the D.C. Circuit decision11 directing
EPA to ensure that the standard did not duplicate the regulation of fine particles.
EPA’s standard for PM , as modified by the 1997 changes to the PM NAAQS, was
10
challenged shortly after promulgation. Concluding that PM was a “poorly matched
10
indicator” for thoracic coarse particles because it included the smaller PM category
2.5
as well as the larger particles, the Court of Appeals remanded the standard to EPA.
The proposed PM daily standard is among the less stringent within the range
2.5
of alternative levels recommended by EPA staff, and the annual standard is not as
stringent as the standard recommended by the independent Clean Air Science
Advisory Committee (CASAC) mandated under Section 109(d)(2) of the CAA (see
9 The use of public welfare in the CAA “includes, but is not limited to, effects on soils,
water, crops, vegetation, manmade 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, whether caused by
transformation, conversion, or combination with other air pollutants” (42 U.S.C. 7602(h)).
10 Based on the findings in the EPA Criteria Document and Staff Paper, and the CASAC’s
concurrence, that studies reviewed do not provide sufficient evidence regarding long-term
exposure to warrant continuation of an annual standard, see 71 Federal Register 2653,
Section III. Rationale for Proposed Decision on Primary PM10 Standards, July 17, 2006.
11 American Trucking Associations v. EPA, 175 F.3d 1027, 1053-55 (D.C. Cir. 1999).

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CRS-4
discussion in the next section of this report). The PM
standards, as proposed, are
10-2.5
similar to the recommendations of the staff and the CASAC.
In response to the discrepancies between the proposal and the recommendations,
the EPA Administrator emphasized that the standard is a proposal subject to public
comment and that the agency planned to assess information contained in more recent
studies.12 The Administrator indicated that his decision required consideration of a
number of factors and “judgment based upon an interpretation of the evidence.” The
Administrator relied on the evidence of long-term exposure studies as the principal
basis for retaining the annual PM standard.13 EPA has asked for broad public
2.5
comment on the proposed standards for fine and coarse particles, as well as comment
on a range of alternative standards, including no changes to the current 1997 annual
and daily standards and more stringent standards than proposed — similar to those
recommended by EPA staff and the CASAC.
Alternative PM Standards
Section 109(d)(1)) of the CAA requires EPA to review the criteria that serve as
the basis for the NAAQS for each covered pollutant every five years, to either
reaffirm or modify established NAAQS. The process for setting and revising
NAAQS consists of the statutory steps incorporated in the CAA over a series of
amendments. Several other steps have also been added by the EPA, by executive
orders, and by subsequent regulatory reform enactments by the Congress.
The CAA is quite specific on certain steps of the process — in particular, on the
preparation of a “criteria document” summarizing the scientific information, on the
review of that document by an independent scientific committee, on the criteria to be
used by the Administrator in deciding on the final standard, and on the procedural
process for promulgating the standard. In addition, EPA has administratively added
a key step, the preparation of a “staff paper” that summarizes the criteria document
and lays out policy options. Supplemental to public comment, the CASAC reviews
each criteria document and staff paper as it is prepared, recommends improvements,
and, after further meetings and reviews, signs off only when the CASAC panel of
members is convinced that each accurately reflects the status of the science. The
CASAC closure letter indicates that the majority of the CASAC panel members agree
that the criteria document and the staff paper provide an adequate scientific basis for
regulatory decisionmaking.
12 Transcript of December 20, 2005, media conference call with EPA Administrator
Johnson, available at [http://www.epa.gov/air/particles/actions.html], visited January 4,
2005.
13 For the EPA Administrator’s rationale for proposing to retain the current level for the
annual PM standard and recognition of the CASAC’s recommendation not endorsing this
2.5
approach, see 71 Federal Register 2650-2653.

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CRS-5
EPA released the report Air Quality Criteria for Particulate Matter on October
29, 2004, following sign-off by the CASAC.14 The criteria document is the result of
a rigorous evaluation of research information relevant to PM NAAQS criteria
development from pertinent literature available between early 1996 through April
2002, and a few relevant studies published through 2003. In July 2005, EPA
published its final “staff paper,” prepared by EPA’s Office of Air Quality Planning
and Standards (OAQPS) staff.15 The staff paper presents the staff conclusions and
recommendations on the elements of the PM standard based on evaluation of the
policy implications of the scientific evidence contained in the criteria document and
the results of quantitative analyses (e.g., air quality analyses, human health risk
assessments, and visibility analyses) of that evidence.
The staff paper concluded, and most of the CASAC panel concurred, that the
scientific evidence supported modifying the PM standard.16 Recognizing certain
limitations of the data, a range of alternatives were presented for consideration for
modifying the current PM NAAQS. The staff paper and CASAC recommendations
for PM were similar to those included in the December 2005 proposal, but those for
10
PM included a range of more stringent levels than those proposed. In addition, the
2.5
majority of the CASAC panel “did not endorse the option of keeping the annual
standard at its present value.”17 Recommendations were based on the primary or
“health based” standards; as is the case with the current and proposed PM NAAQS,
secondary standards were recommended to be the same as the associated primary
standards. Table 1 summarizes the recommendations for PM NAAQS.
2.5
14 69 Federal Register 63111. The Criteria Document and information about the review
process are available at [http://www.epa.gov/ttn/naaqs/standards/pm/s_pm_index.html].
15 EPA. “Review of the National Ambient Air Quality Standards for Particulate Matter:
Policy Assessment of Scientific and Technical Information, OAQPS Staff Paper,” Office of
Air Quality Planning and Standards, EPA-452/R-05-005, July 2005. The staff paper can be
accessed at [http://www.epa.gov/ttn/naaqs/standards/pm/s_pm_cr_sp.html].
16 Clean Air Scientific Advisory Committee (CASAC) Particulate Matter (PM) Review
Panel’s Peer Review of the Agency’s Review of the National Ambient Air Quality Standards
for Particulate Matter: Policy Assessment of Scientific and Technical Information (Second
Draft PM Staff Paper, January 2005), EPA-SAB-CASAC-05-007, June 6, 2005, available
at [http://www.epa.gov/sab/panels/casacpmpanel.html], visited January 6, 2005.
17 Ibid, pg. 7. “Of the options presented by EPA staff for lowering the level of the PM
standard, based on the above considerations and the predicted reductions in health impacts
derived from the risk analyses, most Panel members favored the option of setting a 24-hour
PM NAAQS at concentrations in the range of 35 to 30 g/m3 with the 98th percentile form,
2.5
in concert with an annual NAAQS in the range of 14 to 13 g/m3. The justification for not
moving to the lowest staff-recommended levels within these ranges is that these were
generally associated with only small additional predicted reductions in risk.”

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CRS-6
Table 1. Current, Proposed, and Alternative
PM Primary (Health) NAAQS
2.5
24-hour Primary
Annual Primary
PM NAAQS Options
2.5
(98th percentile)
(arithmetic mean)
Current NAAQS (1997)
65 :g/m3
15 :g/m3
EPA Proposed Rule
35 :g/m3
15 :g/m3
EPA Staff Paper
35-25 :g/m3
15 :g/m3
or
40-30 :g/m3
14-12 :g/m3
CASAC
35-30 :g/m3
14-13 :g/m3
Source: Prepared by the Congressional Research Service (CRS), with information from
EPA’s December 20, 2005, proposal and related technical documents,18 available at
[http://www.epa.gov/air/particles/actions.html].
Potential Impacts of More Stringent PM Standards
The Clean Air Act requires that NAAQS be set solely on the basis of public
health and welfare protection, whereas costs and feasibility are generally taken into
account in NAAQS implementation (a process that is primarily a state responsibility).
When the December 2005 proposal was released, however, EPA announced that it
is completing a regulatory impact analysis (RIA) assessing the costs and benefits of
setting the standard at both the proposed and alternative levels. EPA hopes to
publish the RIA in early 2006.19 Preliminary estimates from EPA and others of risk
reductions and affected areas provide some insight into potential impacts of the
proposed PM NAAQS.
Health Effects
EPA’s most recent review found that the data since 1997 reinforce the
associations between exposure to PM and numerous cardiovascular and respiratory
health problems, including aggravated asthma, chronic bronchitis, reduced lung
function, irregular heartbeat, nonfatal heart attacks, and premature death. The
CASAC commented that “numerous epidemiological studies that are reviewed in this
chapter [chapter 2] have shown statistically significant associations between the
concentrations of ambient air PM and PM (including levels that are lower than the
2.5
10
18 EPA’s final staff paper and the CASAC review of the EPA staff paper (see references
earlier in this report).
19 Summary results of analyses EPA has conducted as part of the process of developing a
regulatory impacts analysis (RIA), EPA White Paper Preliminary Analyses of Proposed
PM2.5 NAAQS Alternatives, December 21, 2005, have been posted on the EPA website and
can be accessed at [http://www.epa.gov/air/particles/pdfs/whitepaper20051220.pdf].

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CRS-7
current PM NAAQS) and excess mortality and morbidity.”20 Although EPA and the
CASAC recognize gaps in certain aspects of the data, they concurred that the
evidence supported updating the PM NAAQS.
When promulgating the 1997 PM NAAQS, EPA estimated that compliance
2.5
would result in the annual prevention of 15,000 premature deaths, 75,000 cases of
chronic bronchitis, and 10,000 hospital admissions for respiratory and cardiovascular
disease, as well as other benefits. These estimates have been the subject of significant
debate and reanalysis. Since 1998, with dedicated funding from Congress, EPA has
accelerated its research and reanalysis on PM to better understand the potential
2.5
associated health effects and to develop ways to reduce risks.21 The funding has
supported numerous EPA intramural and extramural PM research projects and the
establishment of five university-based PM research centers around the country.
EPA’s most recent review has increased its confidence in earlier findings associating
exposure to PM to increases in respiratory health problems, hospitalizations for
2.5
heart and lung disease, and premature death, particularly for children, the elderly, and
those with preexisting heart and lung disease.22
Although EPA has not completed a national analysis of the proposed and
alternative PM standards, it has assessed potential risk reduction for PM standards
in several cities using modeling for assessing the effects of other EPA air quality
regulations. Using data from the nine cities EPA studied, the American Lung
Association (ALA) estimated fine particulates would result in 4,729 premature deaths
under the current PM standard. ALA developed a table consolidating the EPA data
2.5
from the nine cities23 to illustrate comparative risk reductions of several alternative
PM standards. According to ALA’s analysis, EPA’s proposed PM standard would
2.5
reduce premature deaths by 22%, compared with the current standard; further, the
ALA projected that a combination of the CASAC’s most stringent recommendations
for both the daily and annual levels (30 :g/m3 daily with 13 :g/m3 annual) would
result in a potential 48% reduction. Opposing views suggest that EPA’s proposed
standard would provide limited, if any, tangible public health benefits and could
result in significant costs to states and industry. Some opposed to more stringent PM
NAAQS claim that more recent studies of health effects attributable to PM actually
20 Page 5 of the CASAC review. The Criteria Document and information about the review
process are available at [http://www.epa.gov/ttn/naaqs/standards/pm/s_pm_index.html].
21 Congress increased EPA’s appropriations for particulate matter research from $18.8
million in FY1997 (H.Rept. 104-812) to $49.6 million in FY1998 (H.Rept. 105-297). PM
research appropriations averaged more than $60 million per year from FY1999 through
FY2004, and Congress provided $60.5 million for FY2005. Congress did not specify PM
research funding in EPA’s FY2006 appropriation but included $61.0 million for NAAQS
research prior to a 0.476% across-the-board rescission (P.L. 109-54; H.Rept. 109-188).
22 For EPA criteria and technical documents in support of the December 20, 2005, proposal
and the 1997 NAAQS, see [http://www.epa.gov/ttn/naaqs/standards/pm/s_pm_index.html].
23 Boston, Detroit, Los Angeles, Philadelphia, Phoenix, Pittsburgh, St. Louis, San Jose, and
Seattle; see [http://www.cleanairstandards.org/article/articleview/402/1/41/].

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CRS-8
demonstrate that risk estimates are lower and less statistically significant than they
were in 1997, when the last standard was set.24
Figure 1. Number of Premature Deaths in Nine U.S. Cities, Estimated by
the American Lung Association for Alternative PM NAAQS
2.5
Source: The American Lung Association. Compiled with data from EPA, Particulate Matter Health
Risk Assessment for Selected Urban Areas, Appendix A. The nine cities are Boston, Detroit, Los
Angeles, Philadelphia, Phoenix, Pittsburgh, St. Louis, San Jose, and Seattle. All PM NAAQS
2.5
alternatives are shown as µg/m³ for the annual and 24-hour standards at the 98th percentile, except as
noted; see [http://www.cleanairstandards.org/article/articleview/402/1/41/]).
EPA and most of the CASAC panel members concluded that there was a lack
of evidence (often a lack of studies) on long-term effects of specific PM10-2.5
measurements. The proposal would revoke the current annual PM standard and
10
would not include an annual standard for newly defined PM
The proposal to
10-2.5.
redefine coarse particles PM
to include only those particles typically found in
10-2.5
urban areas is primarily based on the finding, as defined by the CASAC, that “the
evidence for the toxicity of PM
comes from studies conducted primarily in urban
10-2.5
areas and is related, in large part, to the re-entrainment of urban and suburban road
dusts as well as primary combustion products.”25 The proposed PM
standard
10-2.5
would exempt sources such as windblown dust and soils and agricultural and mining
operations, which are believed to be largely composed of less-toxic components for
which evidence of health issues is either limited or nonexistent. This approach, and
how EPA will distinguish the sources during its implementation, raises a number of
questions, and the agency has solicited detailed comments on this issue.
24 Communication with Mr. Frank Maisano, Media Contact for the Electric Reliability
Coordinating Council, January 17, 2006.
25 Pages 7-8 of the CASAC review. The Criteria Document and information about the review
process are available at [http://www.epa.gov/ttn/naaqs/standards/pm/s_pm_index.html].

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CRS-9
EPA’s most recent report on air quality trends26 reported that nationally, in 2003,
fine particle concentrations were the lowest since monitoring began in 1999, and
coarse particle concentrations were the second lowest since 1988 (concentrations
were lower in 2002). Despite the decline, the EPA reports that there were 62 million
people in 97 counties with monitors measuring fine and coarse particles above the
current NAAQS in 2003.
Promulgation of a NAAQS sets in motion a process under which the states and
EPA first identify geographic nonattainment areas — those areas failing to comply
with the NAAQS, based on monitoring and analysis of relevant air quality data. The
proposed PM NAAQS are expected to increase the number of areas (typically defined
by counties or portions of counties) in nonattainment.
Impacts of NAAQS Implementation
Implementation of the 1997 PM standard, delayed several years by litigation, the
lack of monitoring capability, and other factors, is ongoing. EPA’s recent final
designation of 39 geographical areas, composed of 208 counties in 20 states and the
District of Columbia, in nonattainment (those areas with or contributing to air quality
levels exceeding the annual and 24-hour standards) with the PM NAAQS became
2.5
effective on April 5, 2005. A direct comparison of nonattainment with the current
standard and the proposal is not available. However, EPA projected that the numbers
of counties with monitors that would not attain the PM NAAQS could increase
2.5
from 116 counties (those with monitors within the total 208 counties), based on the
current standard, to 191, with the proposed PM NAAQS, by 2010. Taking into
2.5
account those areas without monitors but contributing to air quality levels exceeding
the standard, and other factors considered by the Agency when determining the
designations, the total number of a counties likely to be in nonattainment with the
proposed standard would be even larger.
Table 2 below summarizes the EPA’s comparative nonattainment designation
projections of counties with monitors for 2010 and 2015, based on the current PM2.5
standard, the proposed standard, and other alternative PM standards that EPA
2.5
considered. EPA notes that its projections are based on 2001-2003 monitoring data,
whereas the actual nonattinment designations would be based on 2004-2006
monitoring data.27 EPA’s projections also take into account those PM reductions that
the agency expects will occur as the result of air quality regulations promulgated in
26 EPA, The Particle Pollution Report: Current Understanding of Air Quality and Emissions
through 2003 EPA 454-R-04-002, December 2004 [http://www.epa.gov/
airtrends/aqtrnd04/pm.html].
27 In a separate but related action, EPA proposed to amend its national air quality monitoring
requirements, including those for monitoring particle pollution, to help federal, state, and
local air quality agencies “improve public health protection and inform the public about air
quality in their communities” by taking advantage of improvements in monitoring
technology. Like the proposed PM NAAQS, this proposal had not been published in the
Federal Register as of the writing of this CRS report. Information on the proposed changes
are available at [http://www.epa.gov/air/particlepollution/actions.html].

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CRS-10
2005,28 including the Clean Air Interstate Rule (CAIR), the Clean Air Mercury Rule
(CAMR), and the Clean Air Visibility Rule (CAVR).
Table 2. Counties with Monitors Projected To Be in
Nonattainment for Current, Proposed, and
Alternative PM NAAQS
2.5
2015 with
2010
CAIR/CAVR/CAMR
PM NAAQS
2.5
Options (24-hour and
National
East
West
National
East
West
annual :g/m3
15/65 — current
116
102
14
32
18
14
15/35 — proposed
191
141
50
76
30
46
14/35
235
185
50
96
50
46
15/30
326
264
62
178
116
62
Source: EPA White Paper Preliminary Analyses of Proposed PM2.5 NAAQS Alternatives,
Office of Air Quality Planning and Standards, Office of Air and Radiation, December 21, 2005.
Notes: CAIR = Clean Air Interstate Rule, CAMR= Clean Air Mercury Rule, and CAVR = the
Clean Air Visibility Rule, promulgated in 2005.
Following formal designation (a process that EPA estimates will not be completed
before April 2010 for the proposed PM NAAQS), the states have three years to submit
State Implementation Plans (SIPs) that identify specific regulations and emission control
requirements that will bring an area into compliance. If new or revised SIPs for
attainment establish or revise a transportation-related emissions allowance (“budget”),
or add or delete transportation control measures (TCMs), they will trigger “conformity”
determinations. Transportation conformity is required by the CAA, Section 176(c) (42
U.S.C. 7506(c)), to prohibit federal funding and approval for highway and transit projects
unless they are consistent with (“conform to”) the air quality goals established by a SIP
and will not cause new air quality violations, worsen existing violations, or delay timely
attainment of the national ambient air quality standards.29
EPA has not yet released an analysis of the potential economic impacts associated
with designating areas as nonattainment for particulate matter based on the proposed PM
NAAQS. 30 Implementation of the proposed PM NAAQS is further complicated by the
28 For more information on these and other recent EPA’s air quality regulations, see
[http://www.epa.gov/cleanair2004/].
29 For additional information on conformity, see CRS Report RL32106, Transportation
Conformity Under the Clean Air Act: In Need of Reform?, by James E. McCarthy.
30 Illustrating the complexity of such analyses is the divergence of projected impacts of the
ozone NAAQS. A 2002 EPA analysis (U.S. EPA, Office of Air and Radiation, “The
Historical Record: Nonattainment Status and Economic Growth,” February 26, 2002) found
that ozone nonattainment designations had no net negative impact on those areas. In
(continued...)

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CRS-11
change in definition for coarse particles. Changing the indicator from PM to PM
10
10-2.5
requires establishing new monitoring and measurement protocols. In addition, EPA has
solicited comments on options but has not determined how it will distinguish between
the “urban” sources of coarse particles covered by the proposal and the exempted “rural”
sources.
Impacts on specific areas would be speculative at best because implementation of
any revised PM NAAQS would be several years off. For example, states would not be
required to meet the proposed PM standard until April 2015 (April 2020 if qualified
2.5
for extension). With regard to the current NAAQS, states are required to submit
“implementation” plans for how they will meet the PM NAAQS by April 2008 and
2.5
must be in compliance by 2010, unless they are granted a five-year extension.
Reaction to the Proposed PM NAAQS
Well before the EPA formally proposed revising the NAAQS, stakeholders were
providing evidence and arguments at public hearings and other forums for their preferred
recommendations — in general, business and industry oppose more stringent standards,
and public health and environmental interest groups advocate tighter standards. EPA
received thousands of comments during various stages of development of the criteria
document and in response to drafts of the EPA staff paper. Many of the public interest
groups, as well as the association representing state air quality regulators,31 felt that the
December 2005 proposal should have been more stringent — at a minimum, at the lower
levels within the range of EPA staff/CASAC recommendations. Based on several media
articles and available press releases:
Proponents of more stringent standards generally assert that
! the standards should be at least as stringent as the more stringent
combined daily and annual levels recommended in the EPA staff paper
and those recommended by the CASAC based on its review of the
criteria and the EPA staff analysis;
! scientific evidence of adverse health effects are more compelling than
when the standards were revised in 1997;
30 (...continued)
contrast, a study conducted by NERA Economic Consulting for the American Petroleum
Institute (API), found that meeting the 2010 ozone attainment deadline will lead to a $3
billion reduction in economic output in the Philadelphia region in 2011 (Economic Impact
of 8-Hour Ozone Attainment Deadlines on Philadelphia Region, September 2005;
[http://api-ec.api.org/filelibrary/NERA_API_Philadelphia_Report.pdf]). An API summary
of the report indicates that delaying the eight-hour ozone NAAQS attainment deadline to
2015 would lower the cost to the local economy to $100 million per year
([http://api-ep.api.org/economics/index.cfm?bitmask=002003002000000000]).
31 Personal communication with Mr. William Becker, Executive Director, State and
Territorial Air Pollution Program Administrators/Association of Local Air Pollution Control
Officials (STAPPA/ALAPCO), January 5, 2006.

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CRS-12
! exclusion of rural sources from the coarse particle (PM ) standard is not
10
sufficiently protective of human health and would be difficult to
distinguish and implement;
! more stringent standards ensure continued progress toward protection of
public health with an adequate margin of safety as required by the CAA,
in addition to avoidance of other adverse health effects;
! welfare effects, such as visibility, crop yield and forest health, will be
enhanced.
Critics of more stringent PM NAAQS contend that
! more stringent (and in some cases the existing) standards are not
justified by the scientific evidence; the proposal does not take into
account hundreds of studies completed since the 2002 cut-off;
! requiring the same level of stringency for all fine particles without
distinguishing sources is unfounded;
! costs and adverse impacts on regions and sectors of the economy are
excessive; some of those identified as “urban” sources contend
exemption of rural particles may result in a disproportional compliance
burden;
! revising the standards could impede implementation of the existing PM
NAAQS and the process of bringing areas into compliance, given the
current status of this process; revisions could also impede efforts to meet
air quality regulations promulgated in 2005, such as the Clean Air
Interstate Rule (CAIR);32
! the benefits (and costs) associated with implementation of the 1997 PM
standard, as well as compliance with recent EPA air quality regulations,
have not yet been realized.
EPA has responded to both sides by emphasizing that the Agency’s conclusions and
decisions are provisional and proposed in nature, and the agency is soliciting comment
(90-day comment period from the date of publication in the Federal Register) regarding
its supporting analysis and a variety of alternative PM NAAQS. In addition to written
comments, EPA intends to hold public hearings at the end of February in Philadelphia,
Chicago, and San Francisco. EPA also declares its intention to review and evaluate
significant new studies developed since 2002 and those published since the close of the
criteria document.33
Congressional Activity
Because of health and cost implications, NAAQS decisions have often been the
source of significant concern to many in Congress. The evolution and development of
the PM (and ozone) NAAQS, in particular, have been the subject of extensive oversight.
32 EPA, Clean Air Interstate Rule, Clean Air Mercury Rule, and Clean Air Nonroad Diesel
Rule. [http://www.epa.gov/cleanair2004/]
33 71 Federal Register 2625, July 17, 2006.

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CRS-13
Congress enacted legislation specifying deadlines for implementation of the 1997
standard, funding for monitoring and research of potential health effects, and the
coordination of the PM (and ozone) standard with other air quality regulations. Most
recently, during the first session of the 109th Congress, the Senate Committee on
Environment and Public Works, Subcommittee on Clean Air, Climate Change, and
Nuclear Safety, held a hearing on November 10, 2005, regarding implementation and
review of the PM NAAQS.34
In 1997, when the current standard was promulgated, Congress held 28 days of
hearings on the EPA rule. Since FY1998, in an effort to expedite research and strengthen
the science underlying EPA’s review of the standard, Congress has appropriated funding
specifically for PM research annually ($60.5 million for FY2005)35. The research,
including reanalysis of key studies underlying the 1997 standard, has largely confirmed
EPA’s earlier conclusions, although new questions have been raised regarding the
methodology used in some of the studies.
Because of the potential impacts PM NAAQS could have on public health and the
economy, EPA’s reassessment of and proposed modifications to these standards will
likely be of continued interest to Congress.
Conclusions
EPA’s December 20, 2005, announcement of its proposal to modify the existing PM
NAAQS following completion of its statutorily required review has sparked interest and
conflicting concerns among a diverse array of stakeholders, and in Congress. As
evidenced by the history of the PM NAAQS, the level of scrutiny and oversight will
likely increase as the agency proceeds toward its final decision regarding the PM
NAAQS by September 2006. Because the health and economic consequences of
particulate matter standards are so potentially significant, the PM NAAQS are likely to
remain a prominent issue of interest during the second session of the 109th Congress.
Tightening the PM NAAQS, as proposed, will result in more areas classified as
nonattainment and needing to implement new controls on particulate matter. States and
local governments would be required to develop and implement new plans for addressing
emissions in those areas that do not meet any new standards. A stricter standard may
mean more costs for the transportation and industrial sectors, including utilities,
refineries, and the trucking industry, affected by particulate matter controls. In terms of
public health, a stricter standard may mean fewer adverse health effects for the general
34 U.S. Senate Committee on Environment and Public Works, Subcommittee on Clean Air,
Climate Change, and Nuclear Safety, Implementation of the Existing Particulate Matter and
Ozone Air Quality Standards, November 10, 2005.
35 Congress increased EPA’s appropriations for particulate matter research from $18.8
million in FY1997 (H.Rept. 104-812) to $49.6 million in FY1998 (H.Rept. 105-297). PM
research appropriations averaged more than $60 million per year from FY1999 through
FY2004, and Congress provided $60.5 million for FY2005. Congress did not specify PM
research funding in EPA’s FY2006 appropriation but included $61.0 million for NAAQS
research prior to a 0.476% across-the-board rescission (P.L. 109-54; H.Rept. 109-188).

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CRS-14
population and particularly sensitive populations such as children, asthmatics, and the
elderly.
The EPA’s previous review and establishment of PM NAAQS was the subject of
litigation and challenges, including a Supreme Court decision in 2001.36 EPA’s 1997
promulgation of standards for both coarse and fine particulate matter prompted critics to
charge EPA with overregulation and spurred environmental groups to claim that EPA
had not gone far enough. Not only was the science behind the PM NAAQS challenged,
but EPA was also accused of unconstitutional behavior. More than 100 plaintiffs sued
to overturn the standard. Although EPA’s decision to issue the standards was upheld,
for the most part, stakeholders on both sides of the issue continued to advocate their
recommendations for more stringent and less stringent (in some cases no) PM standard.
It would not be surprising if interested parties return to the courts or initiate
challenges after the agency completes its review and promulgates final standards. Thus,
the final form of the current efforts to revise PM NAAQS may not be known for some
time.
36 Whitman v. American Trucking Associations, 531 U.S. 457 (2001). Along with deciding
issues specific to PM and ozone, the Court ruled unanimously that costs could not be
considered in setting primary (health-based) NAAQS.

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