Order Code RL33254
CRS Report for Congress
Received through the CRS Web
Air Quality: EPA’s 2006 Changes to the
Particulate Matter (PM) Standard
Updated September 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 2006 Changes to the
Particulate Matter (PM) Standard
Summary
On September 21, 2006, EPA Administrator Stephen Johnson signed a final
revision to the National Ambient Air Quality Standards (NAAQS) for particulate
matter (PM). EPA reviewed more than 2,000 scientific studies and found that the
evidence continued to support associations between exposure to particulates in
ambient air and numerous significant health problems, including aggravated asthma,
chronic bronchitis, reduced lung function, heart attacks, and premature death in
people with heart or lung disease. EPA estimated that the incremental benefits
associated with the new standards include a reduction of 2,500 to 5,700 premature
deaths, and 165,000 cases or hospital visits for various cardiovascular and respiratory
disease.
The new PM NAAQS would strengthen the existing standard for “fine”
particulate matter 2.5 micrometers or less in diameter (PM ). The existing PM
2.5
2.5
standard promulgated in 1997 is only now beginning to be implemented. The new
standard would cut almost in half the allowable concentration of PM in the air,
2.5
averaged over 24-hour periods, from 65 micrograms 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. EPA has not predicted the
2.5
number of additional counties expected to exceed the new PM standard; however,
2.5
the new areas will likely be expansions of existing areas and other urban populated
areas. States are required to recommend nonattainment areas by December 2007, and
EPA anticipates it will make final designations in December 2009.

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 annual
standard is unchanged at 15 µg/m3 as proposed, which is counter to the
recommendations of the Clean Air Scientific Advisory Committee (CASAC), an
independent scientific body that advises the Administrator. CASAC had
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
new PM NAAQS also would retain the 24-hour standard and revoke the annual
standard for slightly larger, but still inhalable, particles in the range of 10 to 2.5
micrometers (PM ). The EPA recommends that states focus this standard on urban,
10
industrial, and construction sources, but the new standard does not exclude any mix
of particles “dominated by rural windblown dust and soils and PM generated by
agricultural and mining sources,” as proposed.
In addition to the divergence from the CASAC’s recommendation, several
elements of the new PM standard may prove controversial, including the decision not
to exclude rural sources from the coarse particle standard. Some have also
questioned EPA’s strengthening of the standard for all fine particles, without
distinguishing their source or chemical composition. The establishment of PM
NAAQS in 1997 proved controversial and included extensive congressional
oversight. Congress may conduct oversight of the new PM NAAQS, given its
potential for public health and economic impacts. This report will be updated.

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Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
EPA’s Changes to the PM NAAQS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Alternative PM Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Potential Impacts of More Stringent PM Standards . . . . . . . . . . . . . . . . . . . . . . . . 7
Potential Health Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Fine PM (PM ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.5
Coarse PM (PM ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
10
Potential Impacts of NAAQS Implementation . . . . . . . . . . . . . . . . . . . . . . 12
Reaction to the Proposed PM NAAQS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Congressional Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
List of Figures
Figure 1. Number of Premature Deaths in Nine U.S. Cities, Estimated
by the American Lung Association for Alternative PM NAAQS . . . . . . . 10
2.5
List of Tables
Table 1. Final (2006), Proposed and Alternative, and 1997 PM Primary
2.5
(Health) NAAQS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Table 2. EPA’s Predicted Reductions in Adverse Health Effects Associated
with Meeting the New PM Daily (24-hour) NAAQS . . . . . . . . . . . . . . . . . 8
2.5
Table 3. Counties with Monitors Projected To Be in Nonattainment for
Current, New, and Alternative PM NAAQS . . . . . . . . . . . . . . . . . . . . . . . 14
2.5

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Air Quality: EPA’s 2006 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)
Administrator signed revisions to the National Ambient Air Quality Standards
(NAAQS)1 for particulate matter (PM) on September 21, 2006.2 The Agency’s final
regulations include changes to standards for fine and coarse particles and are
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. The schedule for completion of the Agency’s review of the
PM NAAQS is governed by a consent decree resolving a lawsuit filed in March
2003. EPA was required to finalize its decision regarding the PM NAAQS by
September 27, 2006.3
This action is the culmination of EPA’s statutorily required4 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, the new PM NAAQS tighten the current standards
primarily by lowering the daily (24-hour) standard for fine particles smaller than 2.5
microns (PM ). The final PM NAAQS did not include several changes to modify
2.5
the standards for inhalable coarse particles smaller than 10 microns but larger than
2.5 microns (PM ), as proposed. Several public interest groups and scientists,
10
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.
In a fact sheet supporting the new PM NAAQS, EPA estimated the most likely
benefits associated with the new 24-hour PM standard would range from $17
2.5
billion to $35 billion, based on published scientific studies, at a cost of $6 billion.
EPA estimated that the benefits of meeting the annual PM standard, which was not
2.5
1 Sections 108-109 of the Clean Air Act (CAA).
2 The standards have not appeared in the Federal Register as of this writing but are available
on EPA’s website at [http://epa.gov/pm/actions.html].
3 American Lung Assn. v. Whitman (No. 1:03CV00778, D.D.C. 2003), as modified by the
court.
4 Section 109(d)(1)) of the CAA.

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CRS-2
changed, would range from $20 billion to $160 billion a year in 2015, based on
updated analyses, at a cost $7 billion. EPA has not yet released a regulatory impact
analysis (RIA) providing additional details on the national costs and benefits of its
PM NAAQS proposal, and the Agency did not publish an RIA with its proposal in
January 2006.5 EPA had previously estimated that the national air quality regulations
currently in place for reducing PM and other air pollutants from various sources, such
as utilities and diesel emissions, would annually prevent “tens of thousands of
premature deaths and reduce hospitalizations for cardiovascular and respiratory
illness by tens of thousands more...,” resulting in hundreds of billions of dollars in
benefits.6 At the time of the 1997 promulgation, EPA estimated the cost to partially
attain the 1997 PM standard by 2010 at $8.6 billion annually,7 whereas industry
2.5
estimates were several times higher.
This report summarizes EPA’s changes to the PM NAAQS , as compared with
the Agency’s January 17, 2006, proposal (71 Federal Register 2620) and the range
of alternative NAAQS recommended by staff and the independent scientific advisory
committee. This discussion is followed by highlights of potential issues and
concerns associated with the Agency’s actions. For a detailed discussion of the
NAAQS process, see CRS Report 97-722, Air Quality Standards: The
Decisionmaking Process, by John E. Blodgett and Larry B. Parker; for more
information on the implementation of the current PM NAAQS promulgated in
2.5
1997, see CRS Report RL32431, Particulate Matter (PM ): National Ambient Air
2.5
Quality Standards (NAAQS) Implementation, by Robert Esworthy.
EPA’s 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.”8 EPA’s
1997 revisions to the PM NAAQS9 revised the standards established in 198710 that
focused on particles smaller than 10 microns (PM or coarse particles) and
10
5 EPA released interim and “provisional” analyses primarily focused on comparisons of
potential risk scenarios in specified cities and locales. See EPA’s Particulate Matter
Regulatory Actions website at [http://www.epa.gov/air/particlepollution/actions.html].
6 EPA Press release: EPA Particulate Matter Research Report Released, September 9, 2004
[http://www.epa.gov/pmresearch/pm_research_accomplishments/].
7 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.
8 42 U.S.C. 7408(a)(1). 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).
9 62 Federal Register 38652-38896, July 18, 1997.
10 PM NAAQS were promulgated in 1987 (52 Federal Register 24640, July 1, 1987).
10

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CRS-3
introduced standards for “fine” particles smaller than 2.5 microns (PM ) for the first
2.5
time.
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
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 98th
percentile 24-hour standard indicates that a monitoring station can exceed the
standard 2% of the days during the year. For PM and PM , the secondary
2.5
10
NAAQS, which are set at a level “requisite to protect the public welfare,”11 are the
same as the primary standards.12
As modified, the PM and PM standards would be as follows:
2.5
10
! PM : strengthen the daily (24-hour) standard, which currently
2.5
allows no more than 65 micrograms per cubic meter (µg/m3), by
setting a new limit of 35 µg/m3, based on the current three-year
average of the 98th percentile of 24-hour PM concentrations; retain
2.5
the annual standard at 15 µg/m3;
! PM : retain the daily (24-hour) standard at 150 µg/m3; eliminate the
10
current annual maximum concentration (50 µg/m3) standard for
PM .13
10
EPA had proposed replacing the current particle size indicator of PM with a
10
range of 10 to 2.5 micrometers (PM
), referred to as inhalable (or thoracic) coarse
10-2.5
particles, and setting a PM
daily standard of 70 µg/m3 rather than the current
10-2.5
PM daily standard of 150 µg/m3. The proposal also included narrowing the focus
10
of the PM
standard on “urban and industrial” sources, and excluding particles
10-2.5
typical to rural areas, including “windblown dust and soils and PM generated by
agricultural and mining sources.” The general concurrence among the CASAC
members was in agreement with EPA staff recommendations that there was a specific
need to address particles in the size of 2.5 to 10 microns.14 However, based on
11 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)).
12 42 U.S.C. 7409(b)(2).
13 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 PM Standards, January 17, 2006.
10
14 Clean Air Scientific Advisory Committee (CASAC) Review of the EPA Staff
Recommendations Concerning a Potential Thoracic Coarse PM Standard in the Review of
(continued...)

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CRS-4
further consideration of the data and in response to comments, EPA did not change
the indicator and did not exclude any areas, but the Agency continues to recommend
that states focus on urban and industrial sources.
The January 17, 2006, proposal to change the indicator of the standard for
coarse particles was in response to a 1999 U.S. Court of Appeals for the D.C. Circuit
decision15 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
10
PM NAAQS, was challenged shortly after promulgation. Concluding that PM was
10
a “poorly matched indicator” for thoracic coarse particles because it included the
smaller PM category as well as the larger particles, the Court of Appeals remanded
2.5
the standard to EPA. The Agency contends that more thorough reasoning in support
of the use of PM as the indicator for inhalable coarse particulate matter in its
10
September 21,2006, final PM NAAQS will satisfy the court.
The revised PM daily standard is among the less stringent within the range of
2.5
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
discussion in the next section of this report). Following the release of the proposal
for revising the PM NAAQS, in response to the discrepancies between the proposal
and the recommendations, the EPA Administrator emphasized that the standard was
a proposal subject to public comment and that the agency planned to assess
information contained in more recent studies.16 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.17
2.5
CASAC strongly disagreed with the Administrator and took the unprecedented
step of urging reconsideration of the proposal.18 Since it was established in the
1970s, this is the first time that the committee has challenged an EPA
Administrator’s decision regarding NAAQS.
14 (...continued)
the National Ambient Air Quality Standards for Particulate Matter: Policy Assessment of
Scientific and Technical Information (Final PM OAQPS Staff Paper, EPA-452/R-05-005,
June 2005), September 15, 2005.
15 American Trucking Assns. v. EPA, 175 F.3d 1027, 1054-55 (D.C. Cir. 1999).
16 Transcript of December 20, 2005, media conference call with EPA Administrator
Johnson, available at [http://www.epa.gov/air/particles/actions.html].
17 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.
18 Letter of Dr. Rogene Henderson, Chair, Clean Air Scientific Advisory Committee, to the
Hon. Stephen Johnson, Administrator, U.S. EPA, March 21, 2006, available at
[http://www.epa.gov.sab/pdf/casac-ltr-06.002.pdf]; or from the federal docket for the
proposed rule Docket ID No. EPA-HQ-OAR-2001-0017, on the Federal Docket website
[http://www.regulations.gov/fdmspublic/component/main].

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CRS-5
EPA had asked for broad public 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. According to the docket for the proposal, EPA received more than
120,000 comments.
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.
EPA released the report Air Quality Criteria for Particulate Matter on October
29, 2004, following sign-off by the CASAC.19 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.20 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.
19 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].
20 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].

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CRS-6
The staff paper concluded, and most of the CASAC panel concurred, that the
scientific evidence supported modifying the PM standard.21 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.”22 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
Table 1. Final (2006), Proposed and Alternative, and 1997
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 (January 2006)
35 :g/m3
15 :g/m3
EPA Staff Paper (December 2005)
35-25 :g/m3
15 :g/m3
or
40-30 :g/m3
14-12 :g/m3
CASAC (December 2005)
35-30 :g/m3
14-13 :g/m3
EPA Final Rule (September 2006)
35 :g/m3
15 :g/m3
Source: Prepared by the Congressional Research Service (CRS), with information from EPA’s final
PM NAAQS (September 21, 2006), EPA’s proposed PM NAAQS (71 Federal Register 2620,
December 20, 2005), and related technical documents,23 available at [http://www.epa.gov/
air/particles/actions.html].
21 Clean Air Scientific Advisory Committee (CASAC) Particulate Matter (PM) Review
Panel, EPA’s Review of the National Ambient Air Quality Standards for Particulate Matter
(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].
22 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.”
23 EPA’s final staff paper and the CASAC review of the EPA staff paper (see references
earlier in this report).

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CRS-7
Potential Impacts of More Stringent PM Standards
In setting and revising the NAAQS, the CAA directs the EPA Administrator to
protect public health with an adequate margin of safety. This language has been
interpreted, both by the Agency and by the courts, as requiring standards based on a
review of the health impacts, without consideration of the costs, technological
feasibility, or other non-health criteria.24 This being the case, the costs and benefits
did not play a central role in shaping the PM NAAQS. Costs and feasibility are
generally taken into account in NAAQS implementation (a process that is primarily
a state responsibility).
EPA analyzed the benefits and costs of implementing the new PM NAAQS to
meet its obligations under Executive Order 12866 (58 Federal Register 51735,
October 4, 1993) and in compliance with guidance from the White House Office of
Management and Budget.25 Although EPA has yet to release an RIA, the Agency has
summarized potential benefits and costs associated with the September 21, 2006,
announcement. EPA did not release an RIA assessing the costs and benefits of
setting the standard at both the proposed and alternative levels with, or subsequent
to, the January 17, 2006, proposal, but conducted interim and “provisional” analyses
regarding certain aspects of potential risk reductions in specific locations. These
analyses did not address national impacts.26
Potential 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
current PM NAAQS) and excess mortality and morbidity.”27 Although EPA and the
CASAC recognize gaps in certain aspects of the data, they concurred that the
evidence supported updating the PM NAAQS.
24 With regard to the non-relevance of cost considerations, see generally Whitman v.
American Trucking Asss., 531 U.S. 457, 465-472, 475-76 (2001).
25 Changes made by EPA in response to OMB recommendations have been documented in
the docket for this action (Docket ID No. EPA-HQ-OAR-2001-0017on the Federal Docket
website [http://www.regulations.gov/fdmspublic/component/main]); for more information
on Executive Order 12866 and OMB’s guidance see OMB’s website, “Regulatory Matters”
at [http://www.whitehouse.gov/omb/inforeg/regpol.html#rr].
26 Analyses are available on EPA’s Particulate Matter Regulatory Actions website at
[http://www.epa.gov/air/particlepollution/actions.html].
27 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].

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CRS-8
EPA’s most recent report on air quality trends28 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.
Fine PM (PM ). EPA estimated the nationwide monetized human health and
2.5
welfare benefits of attaining two alternatives to the current suite of PM NAAQS.
2.5
The monetized health and visibility benefits associated with the change in the PM2.5
daily (24-hour) standard are estimated to range from $9 billion to $75 billion.
Although the supporting analysis has not yet been released, EPA based these
estimates on opinions of outside experts regarding PM and the risk of premature
death, and other benefits criteria. EPA contends that based on published scientific
studies alone, estimated benefits of meeting the new daily (24-hour) PM standards
2.5
range from $17 billion to $35 billion. The monetized benefits include the value of
reductions in health effects summarized in Table 2 below.
Table 2. EPA’s Predicted Reductions in Adverse Health Effects
Associated with Meeting the New PM Daily (24-hour) NAAQS
2.5
Adverse Health Effect
Predicted Reductions
Premature deaths in individuals with pre-
existing cardiovascular and respiratory
2,500 to 5,700
disease
Cases of chronic bronchitis
2,600
Cases of acute bronchitis
7,300
Nonfatal heart attacks
5,000
Hospital admissions for cardiovascular or
1,630
respiratory symptoms
Emergency room visits for asthma
1,200
Cases of aggravated asthma
51,000
Cases of upper and lower respiratory
97,000
symptoms
Days where individuals miss work or school
350,000
Days when individuals must restrict their
activities because of symptoms related to
2 million
particle pollution
Source: Prepared by the Congressional Research Service with data published by the Environmental
Protection Agency on its website for the September 21, 2006, PM NAAQS release [http://epa.gov/
pm/actions.html].
28 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].

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CRS-9
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 re-analysis. Since 1998, with dedicated funding from Congress, EPA
accelerated its research and re-analysis on PM to better understand the potential
2.5
associated health effects and to develop ways to reduce risks.29 The funding
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.30
Although EPA did not complete a national analysis of the proposed and
alternative PM standards at the time of its proposal, it 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 in nine cities under the current 1997 PM standard. ALA
2.5
developed a table consolidating the EPA data from the nine cities31 to illustrate
comparative risk reductions of several alternative PM standards. According to
ALA’s analysis, EPA’s proposed PM standard would reduce premature deaths by
2.5
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 demonstrate that risk
estimates are lower and less statistically significant than they were in 1997, when the
last standard was set.32
29 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).
30 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].
31 Boston, Detroit, Los Angeles, Philadelphia, Phoenix, Pittsburgh, St. Louis, San Jose, and
Seattle; see [http://www.cleanairstandards.org/article/articleview/402/1/41/].
32 Communication with Mr. Frank Maisano, Media Contact for the Electric Reliability
Coordinating Council, January 17, 2006.

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CRS-10
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/]).
Coarse PM (PM ). The new standards retain the existing PM daily (24-
10
10
hour) standard, as promulgated in 1987, to continue to protect against the associated
adverse health and welfare effects. The scientific evidence supports the standard
based on short-term exposure to certain coarse particles, particularly in urban and
industrial areas. The emphasis on urban and industrial areas is based on the findings
reported in the Criteria Document, the Staff Paper, and 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.”33 EPA and most of the CASAC
panel members concluded that there was a lack of evidence (often a lack of studies)
on long-term adverse health effects of specific PM measurements. The new
10
standard revokes the current annual PM standard, as proposed.
10
EPA had proposed replacing the current particle size indicator of PM with a
10
range of 10 to 2.5 micrometers (PM
), referred to as inhalable (or thoracic) coarse
10-2.5
particles, and setting a PM
daily standard of 70 µg/m3 rather than the current
10-2.5
PM daily standard of 150 µg/m3. EPA decided to maintain PM as the indicator
10
10
citing the limited body of evidence on health effects associated with thoracic coarse
particles from studies that use PM
measurements, including the Agency’s
10-2.5
recognition that the only studies of clear quantitative relevance to health effects most
likely associated with thoracic coarse particles used PM . Further, in the Preamble
10
33 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-11
for final revised PM NAAQS, EPA notes that “...having considered the issues raised
in extensive public comment on the proposal, the Administrator’s final decision
differs from that in the proposal regarding whether it is appropriate to revise the
indicator in order to retain protection from coarse particles.”34 Although EPA has not
established NAAQS for PM
, the Agency is promulgating a new reference method
10-2.5
(FRM) for measurement of mass concentrations of PM
in the atmosphere as the
10-2.5
standard of reference for measurements of PM
concentrations in ambient air.
10-2.5
EPA anticipates that the new FRM should provide a basis for gathering scientific
data to support future reviews of the PM NAAQS.35 According to EPA, these
monitors will employ the latest in speciation technology to advance the science, so
that future regulation will provide more targeted protection against the effects of only
those coarse particles and related source emissions.
In addition, EPA did not further qualify the coarse PM indicator to include any
ambient mix of PM
dominated by re-suspended dust from high-density traffic on
10-2.5
paved roads and generated by industrial and construction sources, and exclude any
ambient mix of PM
that is dominated by rural windblown dust and soils and PM
10-2.5
generated by agricultural and mining sources, as proposed. Although there is some
evidence that emissions from the proposed excluded sources are largely composed
of less-toxic components for which evidence of health issues is either limited or
nonexistent, EPA determined that the existing evidence is inconclusive with regard
to whether community-level exposures to thoracic coarse particles are associated
with adverse health effects in non-urban areas. Therefore, EPA is expanding its
research and monitoring36 programs to collect additional evidence on the differences
between coarse particles typically found in urban areas and those typically found in
rural areas.
The proposed approach, and how EPA would distinguish the sources during its
implementation, raised a number of questions and resulted in numerous comments.
According to EPA, with the exception of representatives of those sources (e.g.,
agriculture and mining) who would have been excluded under the proposal, other
commenters, including environmental and public health groups, state and local
agencies, and industries not excluded from the proposed indicator (e.g.,
transportation and construction), opposed the proposed qualified indicator. In its
letter dated March 21, 2006, CASAC stated that while it recognized the scarcity of
information on the toxicity of rural dust it “neither foresaw nor endorsed a standard
that specifically exempts all agricultural and mining sources, and offers no protection
against episodes of urban-industrial PM
in areas of populations less than
10-2.5
100,000.” The Committee recommended the “expansion of our knowledge of the
34 Page 98 of the Preamble released by EPA September 21, 2006; see Section III. Rationale
for Proposed Decisions on Primary PM Standards , pgs. 93-164 of the Preamble on EPA’s
10
website [http://epa.gov/pm/pdfs/20060921_preamble.pdf].
35 Ibid, see Section VI. Reference Methods for the Determination of Particulate Matter as
PM
and PM , beginning on p. 190.
10-2.5
2.5
36 In the Preamble for the final PM NAAQS (p. 126) EPA states that it will be including the
final monitoring rule that it proposed January 17, 2006 (71 Federal Register 2710, see
[http://www.epa.gov/air/particlepollution/actions.html]), in conjunction with the proposed
PM NAAQS, when it publishes the final PM NAAQS.

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CRS-12
toxicity of rural dusts rather than exempting specific industries (e.g. mining,
agriculture)” from control under the standard.
Potential Impacts of NAAQS Implementation
As described earlier, in setting and revising the NAAQS, the CAA directs the
EPA Administrator to protect public health with an adequate margin of safety, which
has been further interpreted to exclude consideration of the costs, technological
feasibility, or other non-health criteria.37 Nevertheless, costs and feasibility
associated with the NAAQS implementation (a process that is primarily a state
responsibility) are a key elements of the debate regarding the new PM NAAQS.
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 tightening of the PM standards are expected to increase the number of
2.5
areas (typically defined by counties or portions of counties) in nonattainment.
Because the current PM daily (24-hour) standard is retained and the annual standard
10
revoked, EPA is not requiring new nonattainment designations for PM .
10
Following formal designation (a process that EPA estimates will not be
completed before April 2010 for the new PM NAAQS), the states have three years
2.5
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),38 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.39
In terms of implementation of existing coarse PM standards, according to EPA,
the Agency has designated 87 areas as nonattainment with the PM NAAQS since
10
1990. Of the original 87 PM areas, 39 have been redesignated to attainment. Of
10
the remaining 48 nonattainment areas, 41 have submitted the required SIPs for PM10
to EPA; 23 PM nonattainment areas have approved SIPs, and 16 of these have
10
“clean air quality” (based on 2002-04 data) but have not yet been formally
redesignated to attainment.40 Although EPA has not provided any quantitative
analysis, the new PM NAAQS are not expected to affect continued implementation
of PM SIPs.
10
37 Lead Industries Association v. EPA, 647 F. 2d 1130 (D.C. Cir. 1980).
38 42 U.S.C. 7506(c).
39 For additional information on conformity, see CRS Report RL32106, Transportation
Conformity Under the Clean Air Act: In Need of Reform? by James E. McCarthy.
40 For more information about EPA’s PM designations see [http://www.epa.gov/air/oaqps/
10
greenbk/pindex.html].

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CRS-13
Although it has not yet published an RIA with supporting analyses, EPA
released estimates of national costs of the new PM NAAQS based on a limited
number of emissions control scenarios that States and Regional Planning
Organizations might implement to achieve the new PM standards. EPA estimated
2.5
that meeting the new PM daily (24-hour) standard would cost $6 billion. Updating
2.5
its assessment of costs of meeting the PM annual standard as promulgated in 1997,
2.5
EPA estimated that meeting this standard, which is unchanged, would cost $7
billion.
Designation of geographical areas and the associated impacts on specific areas
would be speculative at best because implementation of any revised PM NAAQS
would be several years off. States would not be required to meet the proposed PM2.5
standard until April 2015 (April 2020, if qualified for an 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 must be in compliance by 2010,
2.5
unless they are granted a five-year extension.
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, in conjunction with the January
17, 2006, proposal, EPA projected that the numbers of counties with monitors that
would not attain the PM NAAQS could increase from 116 counties (those with
2.5
monitors within the total 208 counties), based on the current standard, to 191, with
the proposed PM NAAQS, by 2010. Taking into account those areas without
2.5
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 3 below summarizes the EPA’s comparative nonattainment designation
projections of counties with monitors for 2010 and 2015, based on the 1997 PM2.5
standard, the new 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.41 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
41 71 Federal Register 2710, January 17, 2006. 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. Information on the proposed
changes are available at [http://www.epa.gov/air/particlepollution/actions.html].

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CRS-14
2005,42 including the Clean Air Interstate Rule (CAIR), the Clean Air Mercury Rule
(CAMR), and the Clean Air Visibility Rule (CAVR).
Table 3. Counties with Monitors Projected To Be in
Nonattainment for Current, New, 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 — new
191
141
50
76
30
46
14/35
235
185
50
96
50
46
15/30
326
264
62
178
116
62
Source: Prepared by the Congressional research Service with data presented in the 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, available
at [http://epa.gov/pm/pdfs/whitepaper20051220.pdf].
Notes: CAIR = Clean Air Interstate Rule, CAMR= Clean Air Mercury Rule, and CAVR
= the Clean Air Visibility Rule, promulgated in 2005.
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,43 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 EPA’s references to the comments in the
Preamble, a review of several comments in the Federal Docket for the January 17,
2006, proposal, and several media articles and available press releases:
42 For more information on these and other recent EPA’s air quality regulations, see
[http://www.epa.gov/cleanair2004/].
43 Personal communication with Mr. William Becker, Executive Director, State and
Territorial Air Pollution Program Administrators/Association of Local Air Pollution Control
Officials (STAPPA/ALAPCO), Jan. 5, 2006.

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CRS-15
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;
! exclusion of rural sources from the coarse particle (PM ) standard
10
is not 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 did 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);44
! 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.
At the time of proposal, EPA responded to both sides by emphasizing that the
Agency’s conclusions and decisions were provisional and proposed in nature, and the
agency solicited 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 held public hearings in early
March 2006 in Philadelphia, Chicago, and San Francisco. EPA also declared its
intention to review and evaluate significant new studies developed since 2002 and
44 EPA, Clean Air Interstate Rule, Clean Air Mercury Rule, and Clean Air Nonroad Diesel
Rule. [http://www.epa.gov/cleanair2004/].

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CRS-16
those published since the close of the criteria document.45 EPA has indicated its
response to many comments in its rationale for the final standards throughout the
Preamble. In some cases, EPA has revised elements of its proposal based on certain
comments; in other cases, EPA lays out its reasoning for disagreeing with other
comments.
Congressional Activity
Congress and a wide variety of stakeholders have closely followed the
development of the new PM NAAQS. Most recently during the 1st and 2nd sessions
of the 109th Congress, the Senate Committee on Environment and Public Works, and
the Committee’s Subcommittee on Clean Air, Climate Change, and Nuclear Safety,
have held hearings regarding implementation and review of the PM NAAQS.46
Several Members of the House Committee on Agriculture submitted a letter to EPA
Administrator Johnson regarding their views as to the consideration of agriculture
concerns in the developments of the PM NAAQS.47
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. 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.
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,48 including $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%
45 71 Federal Register 2625, July 17, 2006.
46 U.S. Senate Committee on Environment and Public Works, Subcommittee on Clean Air:
The Science and Risk Assessment Behind the EPA’s Proposed Revisions to the Particulate
Matter Air Quality Standards, July 19, 2006. Subcommittee on Clean Air, Climate Change,
and Nuclear Safety: EPA’s Proposed Revisions to the Particulate Matter Air Quality
Standards, July 19, 2006, and Implementation of the Existing Particulate Matter and Ozone
Air Quality Standards, Nov. 10, 2005.
47 Letter to EPA Administrator Stephen L. Johnson, from the Chairman, the Ranking
Member, and other Members of the House Committee on Agriculture, July 27, 2006.
48 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.

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CRS-17
across-the-board rescission.49 The research, including re-analysis 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 September 21, 2006, announcement of its final modifications to 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. 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 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 the new standards. A stricter standard
means increased costs for the transportation and industrial sectors most likely
affected by particulate matter controls, including utilities, refineries, and the trucking
industry. In terms of public health, a stricter standard is estimated to result in fewer
adverse health effects for the general 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 2001.50 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 to EPA’s final standards. Thus, the final form of the current efforts to
revise PM NAAQS may not be known for some time
49 P.L. 109-54; H.Rept. 109-188.
50 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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