Order Code RL33254
Air Quality: EPA’s 2006 Changes to the
Particulate Matter (PM) Standard
Updated May 14, 2007
Robert Esworthy and James E. McCarthy
Specialists in Environmental Policy
Resources, Science, and Industry Division

Air Quality: EPA’s 2006 Changes to the
Particulate Matter (PM) Standard
Summary
On October 17, 2006, the EPA published its final revisions to the National
Ambient Air Quality Standards (NAAQS) for particulate matter (particulates, or
PM). The 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. Based on several analytical approaches, the EPA
estimated that compliance with the new NAAQS will prevent 1,200 to 13,000
premature deaths annually, as well as substantial numbers of hospital admissions and
missed work or school days due to illness. Although a tightening of the standards, the
new particulates NAAQS are not as stringent as recommended by EPA staff or the
independent scientific advisory committee (Clean Air Scientific Advisory
Committee, or CASAC) mandated under the Clean Air Act.
The new particulates NAAQS strengthen the pre-existing (1997) standard for
“fine” particulate matter 2.5 micrometers or less in diameter (PM ) by lowering the
2.5
allowable daily concentration of PM in the air. The new daily standard averaged
2.5
over 24-hour periods is reduced from 65 micrograms per cubic meter (µg/m3) to 35
µg/m3. However, the annual PM standard, which is set in addition to the daily
2.5
standard to address human health effects from chronic exposures to the pollutants,
is unchanged from the 1997 standard of 15 µg/m3, although the CASAC had
recommended a tighter annual standard in the range of 13 to 14 µg/m3. Eighty-eight
million people live in the 208 counties designated as “nonattainment” areas for the
1997 PM NAAQS.
2.5
The new 2006 particulates NAAQS also retain the 24-hour standard and revoke
the annual standard for slightly larger, but still inhalable, particles less than or equal
to 10 micrometers (PM ). The EPA abandoned its proposal to replace the particle
10
size indicator of PM with a range of 10 to 2.5 micrometers (PM
), and did not
10
10-2.5
follow through on its proposal to exclude 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 new 2006 particulates NAAQS may prove controversial, including
the decision not to exclude rural sources from the coarse particle standard. Some
have also questioned the EPA’s strengthening of the standard for all fine particles,
without distinguishing their source or chemical composition. In late December 2006,
several states and industry, agriculture, business, and public advocacy groups
petitioned the U.S. Court of Appeals for the District of Columbia Circuit to review
the new 2006 particulates NAAQS. The establishment of particulates NAAQS in
1997 proved controversial and included extensive congressional oversight. Congress
may conduct oversight of the new 2006 particulates NAAQS, given the potential
public health and economic impacts.

Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
EPA’s 2006 Changes to the Particulates NAAQS . . . . . . . . . . . . . . . . . . . . . . . . . 2
Potential Impacts of the 2006 Particulates NAAQS . . . . . . . . . . . . . . . . . . . . . . . 5
EPA’s Monetized Benefits and Cost Estimates . . . . . . . . . . . . . . . . . . . . . . . 6
Potential Health Impacts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Geographical Nonattainment Areas: Potential Impacts . . . . . . . . . . . . . . . . 11
Potential Concerns and Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Fine Particulate (PM ) Primary (Health) Standards . . . . . . . . . . . . . . . . . . 18
2.5
Potential Health Benefits of a More Stringent PM Standard . . . . . . 20
2.5
Coarse Particulate (PM ) Primary Standards . . . . . . . . . . . . . . . . . . . . . . . 23
10
Particle Size Indicator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Rural PM Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
10
Secondary PM and PM Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.5
10
Exclusion of More Recent Research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Synopses of Stakeholder Reaction to the New 2006 Particulates
NAAQS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
List of Figures
Figure 1. Status of Current PM Nonattainment Areas, Based on 2003-2005
10
Air Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Figure 2. Counties Exceeding Revised PM Standards, Based on 2003-2005
2.5
Monitoring Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
List of Tables
Table 1. Primary (Health) NAAQS for PM and PM : Final Revisions (2006),
2.5
10
and Previously Promulgated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Table 2. EPA’s Estimated Total Annual Monetized Benefits and Costs of
Attaining Alternative PM NAAQS in 2020 . . . . . . . . . . . . . . . . . . . . . . . . 8
2.5
Table 3. EPA’s Predicted Reductions in Adverse Health Effects Annually in
2020 Associated with Meeting the New PM NAAQS . . . . . . . . . . . . . . . . 9
2.5
Table 4. Counties with Monitors Identified by EPA To Be in Nonattainment for
the 1997 and the New (2006)Pm NAAQS . . . . . . . . . . . . . . . . . . . . . . . . 14
2.5
Table 5. PM Primary (Health) NAAQS: Final (2006), Proposed and
2.5
Alternatives, and as Promulgated in 1997 . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Table 6. EPA’s Predicted Reductions in Adverse Health Effects Annually in
2020 Associated with Meeting the New PM NAAQS and a More
2.5
Stringent Alternative . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Air Quality: EPA’s 2006 Changes to the
Particulate Matter (PM) Standard
Introduction
The EPA has identified and promulgated National Ambient Air Quality
Standards (NAAQS) under the Clean Air Act (CAA)1 for six principal pollutants
classified by the agency as “criteria pollutants”: particulate matter (PM), ozone (O ,
3
a key measure of smog), nitrogen dioxide (NO , or, inclusively, nitrogen oxides,2
2
NOx), sulfur oxides (SOx, or, specifically, SO ), carbon monoxide (CO), and lead
2
(Pb). On October 17, 2006,3 the EPA published its revisions to the NAAQS for
particulates to provide protection against potential health effects associated with
short- and long-term exposure to particulate matter (including chronic respiratory
disease and premature mortality).
The EPA’s newly promulgated particulates NAAQS modify the standards
established in 19874 that focused on particles smaller than 10 microns (PM , or
10
coarse particles) and standards for “fine” particles smaller than 2.5 microns (PM )
2.5
introduced for the first time with the promulgation of the 1997 PM NAAQS.5 The
2006 revision to the particulates NAAQS are the culmination of the EPA’s most
recent statutorily required periodic review,6 based on its evaluation and analysis of
more than 2,000 scientific studies available between 1997 and 2002, and on
determinations made by the Administrator. Prior to this, the most recent changes to
any NAAQS, a strengthening of the particulate matter and ozone standards, were
promulgated jointly in 1997. The EPA’s recently completed review of the
particulates NAAQS and of the scientific criteria for setting the standards was
initiated not long after the 1997 promulgation.
While the new 2006 particulates NAAQS generally tighten the air quality
standards for particulate matter, the action has caused considerable controversy,
including concerns that the standards are outside the range recommended by both
EPA staff and by the scientific advisory panel established by the Clean Air Act
1 Sections 108-109 of the Clean Air Act (CAA).
2 The NAAQS is for NO ; nitrogen gases that are ozone precursors are referred to as NOx.
2
3 71 Federal Register 61143-61233, October 17, 2006. See also EPA’s PM Regulatory
Actions website at [http://epa.gov/pm/actions.html].
4 52 Federal Register 24634-24715, July 1, 1987.
5 62 Federal Register 38652-38896, July 18, 1997.
6 Section 109(d)(1) of the CAA. According to the statute, the EPA is required to review the
latest scientific studies and either reaffirm or modify the NAAQS every five years.

CRS-2
(CAA).7 Conversely, some continue to contend that available data do not support the
need for stricter standards or, in some cases, even the standards as promulgated in
1997. In late December 2006, 13 states and the District of Columbia petitioned the
U.S. Court of Appeals for the District of Columbia Circuit to review the new 2006
particulates NAAQS. In addition, several groups representing various industry and
agriculture interests (including coal, iron, steel, and corn refiners; oilseed processors;
farmers; and cattle and pork producers, as well as environmental and public health
organizations) also filed petitions to the court challenging the new 2006 NAAQS.
The new 2006 particulates NAAQS are expected to continue to generate national
interest and national debate, and possibly oversight in Congress, as did the previous
changes to the particulates standards promulgated in 1997.
In order to better understand EPA’s actions, this report provides an analysis of
the agency’s final 2006 revisions to the particulates NAAQS, and the estimated costs
and benefits of the new standards and of a more stringent alternatives analyzed. The
report concludes by highlighting concerns and issues raised regarding the revisions
to the particulates standards, including those of the science advisory committee
(Clean Air Scientific Advisory Committee, or CASAC), and actions in Congress.
EPA’s 2006 Changes to the Particulates NAAQS
Establishing NAAQS does not directly limit emissions; rather, it represents the
EPA Administrator’s formal judgment regarding the level of ambient pollution that
will protect public health with an adequate margin of safety. Under Sections 108-
109 of the CAA, Congress mandated that the EPA set national ambient (outdoor) air
quality standards for pollutants whose emissions “may reasonably be anticipated to
endanger public health (primary standards) or welfare8 (secondary)” and “the
presence of which in the ambient air results from numerous or diverse mobile or
stationary sources.” The statute further requires that every five years EPA review the
latest scientific studies and either reaffirm or modify previously established NAAQS.
The CAA is quite specific about certain steps for establishing and reviewing
NAAQS, particularly with regard to the preparation of a “criteria document” that
summarizes the scientific information and resulting criteria that the EPA
Administrator will use to determine the final standard and the procedural process for
promulgating the standard. The Act also established the Clean Air Scientific
Advisory Committee to review criteria and standards, and to advise the
Administrator.9 The CASAC augments its own resources by creating a review panel
7 Section 109(d)(2)of the Clean Air Act.
8 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)).
9 For a discussion of recent issues regarding the CASAC, focusing on the statutory and
(continued...)

CRS-3
of scientists with expertise specific to the pollutant in question. The PM review
panel consisted of 22 national experts, primarily academics and independent
researchers.10 In addition to the CAA requirements, the EPA has chosen to add the
preparation of a “staff paper” that summarizes the criteria document and lays out
policy options. The CASAC also formally reviews the EPA staff paper.11
The EPA’s most recent review found that the scientific evidence since 1997
reinforced the associations between exposure to particulates 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 found that the numerous epidemiological studies
EPA reviewed “have shown statistically significant associations between the
concentrations of ambient air PM and PM (including levels that are lower than the
2.5
10
1997 particulates NAAQS) and excess mortality and morbidity.”12 Further, the EPA
concluded, and most of the CASAC panel concurred, that the scientific evidence
supported modifying the particulates standards.
The primary NAAQS for both PM and PM include an annual and a daily
2.5
10
(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 percentage 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.
As modified and published in the October 17, 2006, Federal Register Notice,
the primary PM and PM standards are as follows:
2.5
10
! PM : strengthens 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 three-year average of
the 98th percentile of 24-hour PM concentrations; retains the
2.5
annual standard at 15 µg/m3.
9 (...continued)
historical role of CASAC and various proposals for change, see CRS Report RL33807, Air
Quality Standards and Sound Science: What Role for CASAC?
by James E. McCarthy.
10 For information regarding the CASAC PM review panel see [http://www.epa.gov/
sab/panels/casacpmpanel.html].
11 The EPA October 2004 criteria document and December 2005 staff paper, the CASAC
reviews, and related information supporting the 2006 revisions to the particulates NAAQS
are available at [http://www.epa.gov/ttn/naaqs/standards/pm/s_pm_index.html].
12 CASAC Particulate Matter (PM) review of EPA’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].

CRS-4
! PM : retains the daily (24-hour) standard at 150 µg/m3 but changes
10
from the 99th percentile to no more than one exceedance per year on
average over three years; eliminates the annual maximum
concentration (50 µg/m3) standard for PM .13
10
For PM and PM , the secondary (welfare) NAAQS are the same as the primary
2.5
10
standards. Table 1 below provides a comparison of the newly revised primary
NAAQS with those previously promulgated for both PM and PM .
2.5
10
Table 1. Primary (Health) NAAQS for PM and PM : Final
2.5
10
Revisions (2006), and Previously Promulgated
Previous NAAQS
EPA Final Rule (2006)
PM (Fine)
2.5
24-Hour Primary Standard
65 :g/m3
35 :g/m3
Annual Primary Standard
15 :g/m3
15 :g/m3
PM (Coarse)
10
24-Hour Primary Standard
150 :g/m3
150 :g/m3
Annual Primary Standard
50 :g/m3
Revoked
Source: Prepared by the Congressional Research Service (CRS), with information from the EPA’s
final particulates NAAQS (71 Federal Register 61143-61233, Oct. 17, 2006), and related technical
documents,14 available at [http://www.epa.gov/air/particles/actions.html].
EPA’s final revisions to the standards for fine particulates (PM ) are the same
2.5
as the agency had proposed in January 2006. However, the final 2006 EPA revisions
to the PM NAAQS, while tightening the standards, are not as stringent as those
2.5
recommended by the CASAC and by the EPA staff. With regard to coarse
particulates, the EPA had proposed replacing the current particle size indicator of
PM with a range of 10 to 2.5 micrometers (PM
), referred to as inhalable (or
10
10-2.5
thoracic) coarse particles, and setting a PM
daily standard of 70 µg/m3 rather than
10-2.5
the current PM daily standard of 150 µg/m3. The proposal also included narrowing
10
the focus of the PM
standard to “urban and industrial” sources and excluding
10-2.5
particles typical to rural areas, including “windblown dust and soils and particulates
generated by agricultural and mining sources.” The range of alternative standards
considered and proposed and issues associated with the EPA’s final decisions are
discussed later in this report.
13 Based on the findings in the EPA PM criteria document and staff paper, and the CASAC’s
concurrence, that the 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 EPA’s final PM staff paper and the CASAC review of the EPA staff paper
[http://www.epa.gov/ttn/naaqs/standards/pm/s_pm_index.html].

CRS-5
Promulgation of NAAQS sets in motion a process under which the states and
the 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 is expected to increase the
2.5
number of areas (typically defined by counties or portions of counties) in
nonattainment. States will not be required to meet the new PM standard until April
2.5
2015 (April 2020, if qualified for an extension15). The EPA estimates that the
effective date for the final designations will not be before April 2010 for the revised
PM NAAQS. Following formal designation, the states have three years to submit
2.5
State Implementation Plans (SIPs), which identify specific regulations and emission
control requirements that will bring an area into compliance.
The EPA is not requiring new nonattainment designations for PM , and it does
10
not anticipate any significant incremental cost impacts of this action. A discussion
of the potential benefits and cost impacts associated with implementation of the new
particulates NAAQS follows.
Potential Impacts of the 2006 Particulates NAAQS
As discussed above, 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.16 This being the case, costs and
benefits did not play a central role in setting the particulates NAAQS. Costs and
feasibility are generally taken into account in NAAQS implementation (a process that
is primarily a state responsibility).
Nevertheless, the EPA released a regulatory impact analysis (RIA) on October
6, 2006,17 to meet its obligations under Executive Order 12866 and in compliance
with guidance from the White House Office of Management and Budget.18 The RIA
only analyzed the benefits and costs of implementing the PM NAAQS. Citing
2.5
15 Under section 172(a)(2)(A) of the CAA, the EPA may grant an area an extension of the
initial attainment date for one to five years (in no case later than 10 years after the
designation date for the area). A state requesting an extension must submit an
implementation plan (SIP) by the required deadline that includes, among other things,
sufficient information demonstrating that attainment by the initial attainment date is
“impracticable.”
16 With regard to the non-relevance of cost considerations, see generally Whitman v.
American Trucking Assns.,
531 U.S. 457, 465-472, 475-76 (2001).
17 EPA’s Regulatory Impact Analysis (RIA) of the 2006 National Ambient Air Quality
Standards for Fine Particle Pollution (PM ), available on EPA’s website at
2.5
[http://www.epa.gov/ttn/ecas/ria.html].
18 58 Federal Register 51735, October 4, 1993. See the White House OMB website,
Regulatory Matters at [http://www.whitehouse.gov/omb/inforeg/regpol.html#rr].

CRS-6
time, data, and modeling limitations, the EPA did not analyze the benefits and costs
of retaining the PM standard. 19
10
The EPA emphasized that the October 2006 RIA differs from typical RIAs in
that it does not analyze the regulatory impact of an action and that it is primarily for
illustrative purposes. The basis for the benefits calculations are reductions in
ambient concentrations of PM resulting from a reasonable, but speculative, array
2.5
of cost-effective state implementation strategies selected by the EPA for purposes of
analysis. The analysis does not model the specific actions that each state will
undertake in implementing the new PM NAAQS. The EPA includes a detailed
2.5
discussion of the limitations and uncertainties associated with the analyses.
EPA’s Monetized Benefits and Cost Estimates20
The EPA estimated incremental costs of attaining the new PM standard based
2.5
on a set of assumptions and extrapolations regarding currently designated
nonattainment areas, likely control strategies and technologies and their associated
engineering costs, emissions inventories and sources, and regional variability. The
EPA emphasizes that the technologies and control strategies selected for analysis
only illustrate one way for nonattainment areas to reach attainment, and that states
will compile and evaluate a variety of programs and adopt those attainment strategies
best suited for their specific local conditions. For purposes of comparing costs with
monetized benefits, the EPA estimated that the total annual mean social cost of
attainment of the new PM NAAQS incremental to attainment of the 1997 standards
2.5
would be $5.4 billion in 2020.
EPA’s estimates of the monetized benefits of complying with the new PM2.5
standard reflect the valuation associated with predicted reductions in the incidence
of certain health and social welfare effects. In the RIA, the EPA presents a variety
of benefits estimates based on several published epidemiological studies, including
an American Cancer Society (ACS) Study21 used in previous RIAs, and the Harvard
Six Cities Study,22 as well as an expert elicitation study conducted by the EPA in
19 The EPA did not release an RIA assessing the costs and benefits at the time of its January
17, 2006, proposal, but conducted interim and “provisional” analyses regarding certain
aspects of potential risk reductions in specific locations associated with an array of PM2.5
standards. [http://www.epa.gov/air/particlepollution/actions.html].
20 EPA’s Regulatory Impact Analysis (RIA) of the 2006 National Ambient Air Quality
Standards for Fine Particle Pollution (PM ), available on EPA’s website at
2.5
[http://www.epa.gov/ttn/ecas/ria.html].
21 Pope, C. Arden, III, et al. “Particulate Air Pollution as a Predictor of Mortality in a
Prospective Study of U.S. Adults.” American Journal of Respiratory and Critical Care
Medicine
151 (1995): 669-674.
22 Dockery, Douglas W. et al. “An Association Between Air Pollution and Mortality in Six
U.S. Cities.” New England Journal of Medicine 329 (1993): 1753-1759. See also the Health
Effects Institute, “Statement: Synopsis of the Particle Epidemiology Reanalysis Project.”
Reanalysis of the Harvard Six Cities Study and the American Cancer Society Study of
Particulate Air Pollution and Mortality
, July 2000 (includes November 1, 2001 errata
(continued...)

CRS-7
2006.23 The EPA estimated the total annual monetized benefits of attaining the new
PM NAAQS would range from $15 billion to $17 billion based on the mortality
2.5
function from the ACS study and morbidity function from the published studies.
Using the mortality function developed using the expert elicitation in conjunction
with the morbidity function from the published studies, the EPA’s total annual
benefits are estimated to range from $8 billion to $76 billion in 2020. The EPA’s
estimated monetized benefits for 2020, like the cost estimates, are based on the
EPA’s projected compliance schedule and are incremental to compliance with the
1997 PM NAAQS by 2015.
2.5
According to the October 6, 2006, RIA, the estimated total annual health and
welfare net benefits (subtracting social costs from the monetized benefits) in 2020
of attaining the new PM NAAQS range from $9 billion to $12 billion, based on
2.5
modeling of morbidity and mortality using published epidemiology studies, and from
$2.4 billion to $70 billion, based on derivation from expert elicitation.
The EPA’s benefits and cost estimates are in terms of 1999 dollars and are
incremental to the agency’s modeled attainment strategy for the 1997 PM NAAQS
2.5
by 2015. The baseline case incorporates expected impacts associated with
implementation of recent national regulations addressing emissions from the power
generation sector (e.g., the Clean Air Interstate Rule [CAIR]24), as well as various
mobile sources, that contribute to lowering PM concentrations in future years.
2.5
Table 2 below presents a range of the EPA’s cost and monetized benefits estimates.
22 (...continued)
sheet), p. I. ([http://www.healtheffects.org/Pubs/Rean-ExecSumm.pdf]).
23 See Chapter 5 of the EPA’s October 6, 2006, RIA for more detail, [http://www.epa.gov/
ttn/ecas/ria.html].
24 70 Federal Register 25162, May 12, 2005.

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Table 2. EPA’s Estimated Total Annual Monetized Benefits and
Costs of Attaining Alternative PM NAAQS in 2020
2.5
(1999 $ billions)
2006 PM NAAQS (15/35 :g/m3)
2.5
Discount Ratea
Benefits
Cost
Net Benefits
Benefits based on American Cancer Society Study Mortality Function and Published Scientific
Literature Morbidity Functions

3%
$17
$5.4
$12
7%
$15
$5.4
$9
Benefits Range based on Expert Elicitation Derived Mortality Function and Published Scientific
Literature Morbidity Functions

Low Mean
High Mean
Low Mean
High Mean
3%
$9
$76
$5.4
$3.5
$70
7%
$8
$54
$5.4
$2.4
$59
Source: Prepared by the Congressional Research Service from the Environmental Protection
Agency’s Regulatory Impact Analysis (RIA) of the 2006 National Ambient Air Quality Standards for
Fine Particle Pollution (PM ),
Table ES-1, p. ES-7, available on the EPA’s website at
2.5
[http://www.epa.gov/ttn/ecas/ria.html]. Estimates and results have been rounded.
Note: Estimates (costs and benefits) reflect attainment in 2020, which includes implementation of
several national programs and are incremental to compliance with the 1997 PM NAAQS.
2.5
a. The discount rates are as recommended in the EPA’s Guidelines for Preparing Economic Analyses
(2000) and OMB Circular A-4 (2003).
In addition to the monetized health benefits estimates, the EPA estimated the
monetary benefits associated with improvements in visibility in selected Class I
national parks and wilderness areas.25 The EPA primarily used a stated preference
approach which estimates values based on sampling surveys asking people what
amount of compensation would be equivalent to a defined improvement in
environmental quality. Extrapolating the results of a study based on a 1988 survey
on recreational visibility value, the EPA estimated visibility “willingness to pay”
benefits to be $530 million in 2020 with attainment of the new PM NAAQS.26
2.5
EPA estimated the cost and benefits of a more stringent alternative PM for
2.5
purposes of comparative analysis. The comparative results are discussed in the
“Potential Concerns and Issues” section of this report.
25 Defined as areas of the country such as national parks, national wilderness areas, and
national monuments that have been set aside under Section 162(a) of the Clean Air Act to
receive the most stringent degree of air quality protection.
26 See Appendix I Visibility Benefits Methodology of the EPA’s October 6, 2006, RIA
[http://www.epa.gov/ttn/ecas/ria.html].

CRS-9
Potential Health Impacts
EPA preliminary estimates of air quality trends released April 200727 indicate
that the national average from fine particle concentrations decreased 7% during the
period 1999, when PM monitoring began, through 2005; for the period 1990-2005,
2.5
the national average from coarse particle concentrations decreased 25%. Despite the
declines, the EPA reports that there were 79 million people living in counties with
monitors measuring fine and coarse particles above the current 1997 PM and the
2.5
1987 PM NAAQS in 2006. A report released by the American Lung Association
10
(ALA) in April 2007 indicated higher average levels of year-round PM in highly
2.5
populated areas of the eastern United States during 2003-2005 compared with
2002-2004. The report noted that outside of the eastern United States., particle levels
continued to drop during the same time period, even in areas that the ALA has
historically ranked as high in particle pollution.28
For purposes of illustration, Table 3 summarizes the EPA’s predicted
reductions in the incidence of a range of adverse health effects annually in 2020 for
the new PM NAAQS (15/35 µg/m3), as reported in its RIA. The range of the
2.5
estimated mean number of reductions in premature deaths is based on the EPA’s
derivations using the ACS and the Harvard Six-City studies. EPA’s mean estimates
for the remaining adverse health effects are based on various epidemiology studies.
The EPA health effects estimates were a primary component of its derivations of the
monetized benefits discussed above.
Table 3. EPA’s Predicted Reductions in Adverse Health Effects
Annually in 2020 Associated with Meeting the New PM NAAQS
2.5
Predicted Reductionsa
Adverse Health Effect
(estimated mean)
Premature deaths in individuals with preexisting
2,500 to 5,700b
cardiovascular and respiratory disease
Cases of chronic bronchitis (age >25)
2,600
Cases of acute bronchitis (age 8-12)
7,300
Nonfatal heart attacks (age >71)
5,000
Hospital admissions for cardiovascular or respiratory
1,630
symptoms (age >17)
Emergency room visits for asthma (age <19)
1,200
27 U.S. EPA, National Air Quality Trends Data: 2006, preliminary estimates released April
30, 2007 [http://www.epa.gov/airtrends/econ-emissions.html]. See also, 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].
28 Estimates are based on air quality data obtained from the U.S. Environmental Protection
Agency’s Air Quality System (AQS), formerly called Aerometric Information Retrieval
System (AIRS). American Lung Association, State of the Air: 2007, released April 2007.
[http://lungaction.org/reports/stateoftheair2007.html].

CRS-10
Predicted Reductionsa
Adverse Health Effect
(estimated mean)
Cases of aggravated asthma (asthmatics age 6-18)
51,000
Cases of upper and lower respiratory symptoms (asthmatics
97,000
age 6-18)
Days when individuals miss work (age 18-75)
350,000
Days when individuals must restrict their activities because
2,000,000
of symptoms related to particle pollution (age 18-65)
Source: Prepared by the Congressional Research Service with data based on epidemiology studies
presented in Chapter 5 of the Environmental Protection Agency Regulatory Impact Analysis of the
2006 National Ambient Air Quality Standards for Fine Particle Pollution (PM )
Oct. 6, 2006, and
2.5
available on the EPA’s website at [http://www.epa.gov/ttn/ecas/ria.html]. Estimates are rounded by
EPA to two significant digits.
a. For consistency with the emissions and benefits modeling, the EPA used national population
estimates based on the U.S. Census Bureau projections. U.S. Bureau of Census. 2000.
Population Projections of the United States by Age, Sex, Race, Hispanic Origin and Nativity:
1999 to 2100. Population Projections Program, Population Division, U.S. Census Bureau,
Available at [http://www.census.gov/population/projections/nation/summary/np-t.txt].
b. The range of estimates reflects the mean estimates derived from the American Cancer Society study
and the Harvard Six-City Study, respectively.
In addition to the improved health benefits based on the epidemiology studies,
the EPA estimated reductions in premature mortality based on the expert elicitation
approach discussed above. The estimates were variable from expert to expert,
ranging from a mean of 1,200 to 13,000 avoided premature deaths annually in 2020
resulting from attainment of the new standards (15/35 :g/m3) incremental to the
EPA’s baseline strategy for the 1997 NAAQS (15/65 :g/m3).
When promulgating the 1997 PM NAAQS, the EPA estimated that
2.5
compliance 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, the EPA accelerated its research and re-analysis on PM to better
2.5
understand the potential associated health effects and to develop ways to reduce
risks.29 The funding supported EPA intramural and extramural PM research projects
and the establishment of five university-based PM research centers around the
country. The EPA’s most recent review has increased its confidence in earlier
findings associating exposure to PM with increases in respiratory health problems,
2.5
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 identify PM
research funding in EPA’s FY2006 appropriation but included $66.8 million for NAAQS
research (H.Rept. 109-465).

CRS-11
hospitalizations for heart and lung disease, and premature death, particularly for
children, the elderly, and those with preexisting heart and lung disease.30
Geographical Nonattainment Areas: Potential Impacts
As described earlier, the Clean Air Act has been interpreted to exclude
consideration of the costs, technological feasibility, and other non-health criteria
when setting and revising the NAAQS. Nevertheless, costs and feasibility associated
with the NAAQS implementation (primarily a state responsibility) are key elements
of the debate regarding the new 2006 particulates NAAQS. The proposed tightening
of the PM standards is expected to increase the number of areas (typically defined
2.5
by counties or portions of counties) in nonattainment, and subsequently result in
increased costs to achieve compliance.
The current PM daily (24-hour) standard has been retained at the 1987 level
10
and the annual standard revoked. The EPA is not requiring new nonattainment
designations for PM , and it does not anticipate any significant incremental cost
10
impacts of this action. The Agency has designated 87 areas as nonattainment with
the PM NAAQS since 1990. As of December 2006, 41 of the original 87 PM
10
10
areas have been redesignated to attainment. Of the remaining 46 nonattainment
areas, 13 areas are currently violating the 1987 standard based on 2003-2005 data.
The remaining counties have submitted the required SIPs for PM but have not yet
10
been formally redesignated to attainment. Figure 1, below, shows the status of
nonattainment of the 1987 PM NAAQS.31
10
30 EPA criteria and technical documents in support of the October 17, 2006, final
particulates NAAQS, the December 20, 2005, proposal, and the 1997 NAAQS, are available
at [http://www.epa.gov/ttn/naaqs/standards/pm/s_pm_index.html].
31 For more information about EPA’s PM designations see [http://www.epa.gov/air/
10
oaqps/greenbk/pindex.html].


CRS-12
Figure 1. Status of Current PM Nonattainment Areas,
10
Based on 2003-2005 Air Quality
Source: U.S. EPA, April 2007.

CRS-13
Designation of geographical areas and the associated impacts on specific areas
would be speculative at best, because implementation of the revised PM NAAQS is
several years off. Initially, areas will be designated nonattainment if they exceed the
standard in 2006-2008. States will not be required to meet the new PM standard
2.5
until April 2015 (April 2020, if qualified for an extension32). With regard to the 1997
PM NAAQS, states are required to submit implementation plans for how they will
2.5
meet the standard by April 2008 and must be in compliance by April 2010, unless
they are granted a five-year extension.33 The EPA published its final “PM2.5
implementation” rule on April 25, 2007, which describes the requirements that states
and tribes must meet in their implementation plans to achieve and maintain
attainment of the 1997 PM NAAQS.34 The rule also provides guidance and
2.5
procedures for establishing controls to achieve and maintain attainment.
Following formal designation (the EPA estimates that the effective date for the
final designations will not be before April 2010 for the revised PM NAAQS), the
2.5
states have three years to submit State Implementation Plans (SIPs), which 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),35 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.
Implementation of the 1997 PM NAAQS — delayed several years by
2.5
litigation, the lack of monitoring capability, and other factors — is ongoing. The
EPA’s final designation of 39 geographical areas, composed of 208 counties in 20
states and the District of Columbia, in nonattainment with the PM NAAQS (those
2.5
areas with or contributing to air quality levels exceeding the annual and 24-hour
standards) became effective on April 5, 2005. A direct national comparison of
nonattainment areas for the 1997 NAAQS and the newly revised PM NAAQS is
2.5
32 Under section 172(a)(2)(A) of the CAA, the EPA may grant an area an extension of the
initial attainment date for one to five years (in no case later than 10 years after the
designation date for the area). A state requesting an extension must submit an
implementation plan (SIP) by the required deadline that includes, among other things,
sufficient information demonstrating that attainment by the initial attainment date is
“impracticable.”
33 For more information on the implementation of the 1997 PM NAAQS promulgated in
2.5
1997, see CRS Report RL32431, Particulate Matter (PM ): National Ambient Air Quality
2.5
Standards (NAAQS) Implementation, by Robert Esworthy.
34 The rule addresses attainment demonstration and modeling; local emission reduction
measures, including reasonably available control technology (RACT), reasonably available
control measures (RACM), and reasonable further progress (RFP); regional emission
reduction strategies; innovative program guidance; emission inventory requirements;
transportation conformity; and stationary source test methods.
35 42 U.S.C. 7506(c).

CRS-14
not available. However, using the most recent available monitoring data (2003-
2005), the EPA identified 143 of those counties with monitors that exceed the new
PM NAAQS. Although the actual nonattainment designations would be based on
2.5
monitoring data from later years,36 comparatively the counties identified reflect an
increase from 73 counties with monitors within the total 208 counties that were
designated by EPA as in nonattinment (exceeding) the 1997 PM NAAQS. Table
2.5
4 presents the geographic distribution of counties with monitors exceeding new 2006
PM
NAAQS identified by EPA, and those exceeding the 1997 PM NAAQS.
2.5
2.5
Table 4. Counties with Monitors Identified by EPA To Be in
Nonattainment for the 1997 and the New (2006)Pm NAAQS
2.5
PM NAAQS (annual/24-hour :g/m3)
2.5
1997 Standard
New 2006 Standard
15/65 :g/m3
15/35 :g/m3
National
West
East
National
West
East
Number of counties with monitors
Total exceeding the
73
9
64
143
32
111
standard
Exceeding the 24-hour
1
0
1
56
9
47
and annual standards
Exceeding the 24-hour
0
0
0
70
23
47
standard only
Exceeding the annual
72
9
63
17
0
17
standard only
Source: Prepared by the Congressional Research Service with data provided by EPA Office of Air
Quality Planning and Standards, Office of Air and Radiation.
Observed on the map in Figure 2 below, the identified areas can seem small
compared with the approximately 3,000 counties in the United States. However,
taking into account those areas without monitors but contributing to air quality levels
exceeding the new 2006 PM and other factors considered by the agency when
2.5
determining the designations, the total number of counties in nonattainment, and the
potential impacts with the new PM NAAQS, is likely to be even larger. The
2.5
number of counties where emissions will need to be controlled may be two or three
times the number of those exceeding the standard, because “nonattainment areas”
include both counties where pollutant concentrations exceed the standard and those
36 Revisions to Ambient Air Monitoring Regulations, final rule, 71 Federal Register
61235-61328, October 17, 2006. In a separate but related action, EPA amended 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 changes is available at
[http://www.epa.gov/air/particlepollution/actions.html].

CRS-15
that contribute to exceedance of the standard in adjoining counties. Entire
metropolitan areas tend to be designated nonattainment, even if only one county in
the area has readings worse than the standard. In addition, the nonattainment counties
tend to have larger populations than those in attainment: 88 million people (about
30% of the U.S. population) live in the 208 counties designated nonattainment for the
current standard. The new standard may affect an even larger percentage of the
population.


CRS-16
Figure 2. Counties Exceeding Revised PM Standards,
2.5
Based on 2003-2005 Monitoring Data
Source: U.S. EPA.

CRS-17
Potential Concerns and Issues
Congress and a wide variety of stakeholders have closely followed the
development of the new 2006 particulates NAAQS since EPA’s review began nearly
10 years ago. Most recently, during the 109th Congress the Senate Committee on
Environment and Public Works and the committee’s Subcommittee on Clean Air,
Climate Change, and Nuclear Safety held hearings regarding implementation and
review of the particulates NAAQS.37 Well before the EPA formally proposed
revising the particulates 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. The EPA received
thousands of comments during various stages of development of the particulates
criteria document and in response to drafts of the EPA particulates staff paper. The
agency reported receiving more than 120,000 comments in response to the January
2006 particulates NAAQS proposal.
The Administrator’s proposed and final decisions represent the first time in
CASAC’s nearly 30-year history that the promulgated standards fall outside of the
range of the scientific panel’s recommendations. In letters dated March 21, 2006,
and September 29, 2006, the CASAC raised its concerns and objections regarding
both PM and PM standards. The Administrator is not required by statute to
10
2.5
follow CASAC’s recommendations; the act (in Section 307(d)(3)) requires only that
the Administrator set forth any pertinent findings, recommendations, and comments
by CASAC and the National Academy of Sciences, and, if his proposal differs in an
important respect from any of their recommendations, provide an explanation of the
reasons for such differences. Courts, in reviewing EPA regulations, also generally
defer to the Administrator’s judgment on scientific matters, focusing more on issues
of procedure, jurisdiction, and standing. Nevertheless, CASAC’s detailed objections
to the Administrator’s decisions and its description of the process as having failed to
meet statutory and procedural requirements could play a role if the standards are
challenged in court.
At the time of its January 2006 proposal, the agency solicited comment
regarding its supporting analysis and a variety of alternative particulates NAAQS.
In addition to soliciting written comments, the EPA held public hearings in early
March 2006 in Philadelphia, Chicago, and San Francisco. As presented in its
rationale for the final standards throughout the preamble of the final rule, in some
cases the EPA has revised elements of its proposal based on certain comments; in
other cases the EPA lays out its reasoning for disagreeing. EPA’s final modifications
to the existing particulates NAAQS have sparked interest and conflicting concerns
37 U.S. Senate Committee on Environment and Public Works, full Committee, 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 13, 2006, and Implementation of the Existing Particulate Matter and Ozone Air Quality
Standards
, November 10, 2005.

CRS-18
among a diverse array of stakeholders and in Congress. The following sections
highlight several areas of interest.
Fine Particulate (PM ) Primary (Health) Standards
2.5
The final revised PM NAAQS, which are the same as proposed, are not as
2.5
stringent as the levels recommended by the independent CASAC and those
recommended by EPA professional staff, as noted above. EPA staff and CASAC
recommendations for PM included a range of levels more stringent than those
2.5
proposed in January and finalized September of 2006. In particular, the majority of
the CASAC panel “did not endorse the option of keeping the annual standard at its
present value
.” According to the CASAC:
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
2.5
the 98th percentile form, in concert with an annual NAAQS in the range of 14
to 13 :g/m3. 38
Table 5 compares the CASAC and EPA staff recommendations for PM primary
2.5
standards, the 1997standards, and 2006 standards as proposed and promulgated.
Table 5. PM Primary (Health) NAAQS: Final (2006), Proposed
2.5
and Alternatives, and as Promulgated in 1997
24-hour Primary
Annual Primary
PM NAAQS Options
2.5
(98th percentile)
(arithmetic mean)
1997 NAAQS
65 :g/m3
15 :g/m3
mid to lower range of
EPA staff paper (December 2005)
35-25 :g/m3
15 :g/m3
or
mid to lower range of
40-30 :g/m3
14-12 :g/m3
CASAC (December 2005)
35-30 :g/m3
14-13 :g/m3
EPA Proposed Rule (January 2006)
35 :g/m3
15 :g/m3
EPA Final Rule (October 2006)
35 :g/m3
15 :g/m3
Source: Prepared by the Congressional Research Service (CRS), with information from the EPA’s
final 2006 particulates NAAQS (71 Federal Register 61143-61233, Oct. 17, 2006), the EPA’s
proposed particulates NAAQS (71 Federal Register 2620, Dec. 20, 2005), and related technical
documents,39 available at [http://www.epa.gov/air/particles/actions.html].
38 CASAC PM Review Panel report, p. 7, June 2005 [http://www.epa.gov/ttn/naaqs/
standards/pm/s_pm_index.html].
39 EPA’s final PM staff paper and the CASAC review of the EPA staff paper (see references
(continued...)

CRS-19
In response to the discrepancies between the proposal and the CASAC
recommendations, EPA Administrator Stephen Johnson 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.40
2.5
CASAC strongly disagreed with the Administrator’s decision regarding the PM2.5
annual standard and took the unprecedented step of urging reconsideration of the
proposal.41
Many public comments received on the EPA’s proposed revisions to the PM2.5
standards, most frequently from environmental and public health organizations,
medical doctors and researchers, and the association representing state air quality
regulators,42 argue for standards as stringent or more stringent than those
recommended by CASAC. In contrast, another group of commenters, generally
representing industry associations and businesses, opposed revising the 1997 PM2.5
standards, in some cases highlighting different aspects of the same research cited by
the CASAC and others supporting tighter standards.43 Some who opposed more
stringent particulates NAAQS called attention to more recent studies of health effects
attributable to particulates that demonstrate risk estimates are lower and less
statistically significant than they were in 1997, when the last standard was set.44
In Section II of the preamble of the final October 2006 revisions, “Rationale for
Final Decisions on Primary PM Standards,” the EPA discusses its final decision
2.5
with respect to the CASAC recommendations regarding the PM annual standard.
2.5
The Administrator differs with the CASAC with regard to the level of uncertainty
associated with the agency’s quantitative risk assessment and whether the results
appropriately serve as a primary basis for a decision on the level of the annual PM2.5
standard. The Administrator further stressed the emphasis placed on the long-term
means of the levels associated with mortality effects in the two key long-term
39 (...continued)
earlier in this report).
40 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, January 17, 2006.
41 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].
42 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.
43 For EPA’s discussion and response to several of these comments, see 71 Federal Register
61143-61233, October 17, 2006, Part II Rationale for Final Decisions on Primary PM2.5
Standards
, Sections B and F, on EPA’s website at [http://epa.gov/pm/actions.html].
44 Communication with Mr. Frank Maisano, Media Contact for the Electric Reliability
Coordinating Council, January 17, 2006.

CRS-20
studies45 in determining the level of the annual standard. CASAC considered the
evidence from specific short-term exposure studies as part of the basis for its
recommendation for a lower annual standard level. As noted above, the CASAC
expressed its objections to the EPA’s final 2006 particulates NAAQS in its
September 29, 2006, letter to Administrator Johnson.46
With regard to PM , the letter stated: “CASAC is concerned that the EPA did
2.5
not accept our finding that the annual PM standard was not protective of human
2.5
health and did not follow our recommendation for a change in that standard.”47 The
letter noted that “there is clear and convincing scientific evidence that significant
adverse human-health effects occur in response to short-term and chronic particulate
matter exposures at and below 15 µ g/m3,
” and noted that 20 of the 22 Particulate
Matter Review Panel members, including all seven members of the statutory
committee were in “complete agreement” regarding the recommended reduction. “It
is the CASAC’s consensus scientific opinion that the decision to retain without
change the annual PM standard does not provide an ‘adequate margin of safety

2.5
... requisite to protect the public health’ (as required by the Clean Air Act)....”48
Potential Health Benefits of a More Stringent PM Standard. In its
2.5
RIA, the EPA estimated the nationwide monetized human health and welfare benefits
of attaining two suites of PM NAAQS: (1) the newly revised PM NAAQS, which
2.5
2.5
include the new 35 µg/m3 daily (24-hour) standard and the unchanged 15 µg/m3
annual standard, and (2) an alternative standard similar to the least stringent of the
CASAC recommendations that includes a tighter annual standard of 14 µg/m3 and
the same 35 µg/m3 daily (24-hour) standard. As discussed previously, the EPA
presented a variety of benefits estimates based on several epidemiological studies,
the American Cancer Society (ACS) Study49 used in previous RIAs, the Harvard Six-
Cities Study,50 and expert elicitation study conducted by the EPA in 2006.51
45 71 Federal Register at 2651, January 17, 2006.
46 Letter of Dr. Rogene Henderson, Chair, Clean Air Scientific Advisory Committee, to the
Hon. Stephen L. Johnson, Administrator, U.S. EPA, September 29, 2006, available at
[http://www.epa.gov/sab/pdf/casac-ltr-06-003.pdf].
47 Letter of Rogene Henderson, Chair of the Clean Air Scientific Advisory Committee, et
al. to Hon. Stephen L. Johnson, EPA Administrator, September 29, 2006, available at
[http://www.epa.gov/sab/pdf/casac-ltr-06-003.pdf].
48 Ibid.
49 Pope, C. Arden, III, et al. “Particulate Air Pollution as a Predictor of Mortality in a
Prospective Study of U.S. Adults.” American Journal of Respiratory and Critical Care
Medicine
151 (1995): 669-674.
50 Dockery, Douglas W. et al. “An Association Between Air Pollution and Mortality in Six
U.S. Cities.” New England Journal of Medicine 329 (1993): 1753-1759. See also the Health
Effects Institute, “Statement: Synopsis of the Particle Epidemiology Reanalysis Project.”
Reanalysis of the Harvard Six Cities Study and the American Cancer Society Study of
Particulate Air Pollution and Mortality
, July 2000 (includes November 1, 2001 errata
sheet), p. I. ([http://www.healtheffects.org/Pubs/Rean-ExecSumm.pdf]).
51 See Chapter 5 of the EPA’s October 6, 2006, RIA for more detail
(continued...)

CRS-21
The EPA estimated that attainment of the more stringent alternative PM2.5
NAAQS would result in $26 billion to $30 billion of total annual benefits in 2020,
based on the ACS mortality function. This compares to a range of $15 billion to $17
billion estimated for compliance with the newly promulgated PM NAAQS (see
2.5
Table 2 and discussion earlier in this report). EPA’s estimate of annual benefits
derived using the expert elicitation ranged from $15 billion to $140 billion for the
more stringent alternative, compared to the agency’s estimates of $8 billion to $76
billion for compliance with the new standard. EPA also estimated the monetary
benefits (“willingness to pay”) associated with improvements in visibility in selected
Class I national parks and wilderness areas would be $1.2 billion in 2020 with
attainment of the more stringent alternative PM standard analyzed, compared to
2.5
$530 million with attainment of the newly revised PM NAAQS.52 EPA estimated
2.5
the total annual cost associated with attainment of the alternative PM NAAQS
2.5
analyzed would be $7.9 billion in 2020, compared to $5.4 billion.
As discussed previously, a key component of the EPA’s monetized benefits
estimates are the agency’s predicted reductions in the incidence of premature deaths
and a range of adverse health effects annually in 2020 associated with compliance of
the new 2006 PM NAAQS. For example, for the more stringent attainment
2.5
strategy analyzed (14/35 µg/m3), the EPA estimated 2,200 to 24,000 fewer premature
deaths based on the expert elicitation. For purposes of illustration, Table 6 provides
a comparison of EPA’s predicted reductions annually for the new PM NAAQS
2.5
(15/35 µg/m3) with a more stringent alternative analyzed (14/35 µg/m3), based on
data from the ACS and Harvard Six-City studies, and various epidemiology studies.
51 (...continued)
[http://www.epa.gov/ttn/ecas/ria.html].
52 See Appendix I Visibility Benefits Methodology of the EPA’s October 6, 2006, RIA
[http://www.epa.gov/ttn/ecas/ria.html].

CRS-22
Table 6. EPA’s Predicted Reductions in Adverse Health Effects
Annually in 2020 Associated with Meeting the New PM NAAQS
2.5
and a More Stringent Alternative
Predicted Reductionsa
(estimated mean)
Adverse Health Effect
More Stringent
PM NAAQS
2.5
Alternative
(15/35 µg/m3)
(14/35 µg/m3)
Premature deaths in individuals with preexisting
2,500 to 5,700b
4,000 to 9,000b
cardiovascular and respiratory disease
Cases of chronic bronchitis (age >25)
2,600
4,600
Cases of acute bronchitis (age 8-12)
7,300
13,000
Nonfatal heart attacks (age >71)
5,000
8,700
Hospital admissions for cardiovascular or
1,630
3,080
respiratory symptoms (age >17)
Emergency room visits for asthma (age <19)
1,200
3,200
Cases of aggravated asthma (asthmatics age 6-18)
51,000
79,000
Cases of upper and lower respiratory symptoms
97,000
153,000
(asthmatics age 6-18)
Days when individuals miss work (age 18-75)
350,000
550,000
Days when individuals must restrict their
activities because of symptoms related to particle
2,000,000
3,300,000
pollution (age 18-65)
Source: Prepared by the Congressional Research Service with data based on epidemiology studies
presented in Chapter 5 of the Environmental Protection Agency Regulatory Impact Analysis of the
2006 National Ambient Air Quality Standards for Fine Particle Pollution (PM )
Oct. 6, 2006, and
2.5
available on the EPA’s website at [http://www.epa.gov/ttn/ecas/ria.html]. Estimates are rounded by
EPA to two significant digits.
a. For consistency with the emissions and benefits modeling, the EPA used national population
estimates based on the U.S. Census Bureau projections. U.S. Bureau of Census. 2000.
Population Projections of the United States by Age, Sex, Race, Hispanic Origin and Nativity:
1999 to 2100. Population Projections Program, Population Division, U.S. Census Bureau,
Available at [http://www.census.gov/population/projections/nation/summary/np-t.txt].
b. The range of reductions in premature deaths estimates reflect the mean estimates derived from the
American Cancer Society study and the Harvard Six-City Study, respectively.
The estimates EPA derived from an expert elicitation approach were only for
mortality. The results were variable from expert to expert, ranging from a mean of
2,200 to 24,000 avoided premature deaths annually in 2020 resulting from attainment
of the more stringent alternative standard (14/35 µg/m3) incremental to the EPA’s
baseline strategy for the 1997 NAAQS (15/65 µg/m3). For attainment of the new
standards (15/35 µg/m3), EPA estimated 1,200 to 13,000 fewer premature deaths
based on the expert elicitation.

CRS-23
Coarse Particulate (PM ) Primary Standards
10
Particle Size Indicator. The 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 to support the annual standard,
10
and that there was a specific need to address particles ranging in size from 2.5 to 10
microns.53 EPA’s January 17, 2006, proposal would have replaced the existing
particle size indicator of 10 micrometers (PM ) with an indicator range of 10 to 2.5
10
micrometers (PM
), referred to as inhalable (or thoracic) coarse particles, and
10-2.5
setting a PM
daily standard of 70 µg/m3 rather than the current PM daily
10-2.5
10
standard of 150 µg/m3. At the time of its proposal, the EPA concluded that the
scientific evidence supported the standard based on short-term exposure to certain
coarse particles, particularly in urban and industrial areas.
In the final 2006 particulates NAAQS, the EPA decided to maintain the PM ,
10
citing the limited body of evidence on health effects associated with thoracic coarse
particles from studies that use PM
measurements. The agency also determined
10-2.5
that the only studies of clear quantitative relevance to health effects most likely
associated with thoracic coarse particles used PM . The new 2006 particulates
10
NAAQS retain the PM indicator and the daily (24-hour) standard of 150 µg/m3.
10
In its September 29, 2006, letter, the CASAC said it was “completely surprised”
at the decision to revert to the use of PM as the indicator for coarse particles, noting
10
that the option of retaining the existing daily PM standard was not discussed during
10
the advisory process and that CASAC views this decision as “highly-problematic
since PM includes both fine and coarse particulate matter.” The CASAC did agree
10
that having a standard for PM was better than no standard.
10
The EPA indicated that it is promulgating a new federal reference method
(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. The
10-2.5
EPA anticipates that the new FRM should provide a basis for gathering scientific
data to support future reviews of the particulates NAAQS.54 According to the EPA,
these monitors will employ the latest in speciation technology to advance the science,
enabling future regulation to provide more targeted protection.
The EPA’s 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 DC
53 Clean Air Scientific Advisory Committee (CASAC) Review of the EPA Staff
Recommendations Concerning a Potential Thoracic Coarse PM Standard in the Review of
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), September15, 2005, [http://www.epa.gov/sab/panels/casacpmpanel.html].
54 71 Federal Register 61143-61233, October 17, 2006, Section VI. Reference Methods for
the Determination of Particulate Matter as PM

and PM
1 0 - 2 . 5
2 . 5
[http://epa.gov/pm/actions.html].

CRS-24
Circuit decision55 directing the EPA to ensure that the standard did not duplicate the
regulation of fine particles. The EPA’s standard for PM , as modified by the 1997
10
changes to the particulates NAAQS, was challenged shortly after promulgation.
Concluding that PM was a “poorly matched indicator” for thoracic coarse particles
10
because it included the smaller PM category as well as the larger particles, the
2.5
Court of Appeals remanded the standard to the EPA. The agency now contends that
it has addressed the concerns raised by the court regarding PM as an indicator for
10
inhalable coarse particulate matter in its rationale in the final 2006 particulates
NAAQS, announced September 21, 2006.56 This is an issue that could potentially be
challenged in further litigation.
Rural PM Sources. In addition to the changes to the coarse particulates
10
indicator, the EPA had proposed narrowing the focus of the PM
standard on
10-2.5
“urban and industrial” sources — particles typical to rural areas including
windblown dust and soils and PM generated by agricultural and mining sources
would not be subject to this standard. Additionally, the EPA proposed revoking the
current 24-hour PM standards, except in areas that have 1) violating monitors, and
10
2) a population of 100,000 or more. The emphasis on urban and industrial areas in
the January 2006 proposal was based on the findings reported in the Criteria
Document, the PM staff paper, and the CASAC conclusion that “the evidence for the
toxicity of PM
comes from studies conducted primarily in urban areas and is
10-2.5
related, in large part, to the re-entrainment of urban and suburban road dusts, as well
as primary combustion products.”57
The EPA’s proposal to exclude any ambient mix of PM
that is dominated
10-2.5
by rural windblown dust and soils and particulates generated by agricultural and
mining sources, and how the EPA would distinguish the sources during its
implementation, raised a number of questions and resulted in numerous comments.
In response to the proposal, in its March 21, 2006, letter to the EPA Administrator,
the CASAC stated that while it had 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 100,000.” The
10-2.5
committee strongly recommended “expansion of our knowledge of the toxicity of
PM
dusts rather than exempting specific industries (e.g., mining, agriculture).”58
10-2.5
55 American Trucking Assns. v. EPA, 175 F.3d 1027, 1054-55 (D.C. Cir. 1999).
56 71 Federal Register 61143-61233, October 17, 2006, Section III.C.3. Decision Not to
Revise PM Indicator
, available at [http://epa.gov/pm/actions.html].
10
57 CASAC review. CASAC reviews, the PM criteria document, staff paper, and related
information, are available at [http://www.epa.gov/ttn/naaqs/standards/pm/s_pm_index.html].
58 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/panels/casacpmpanel.html], 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].

CRS-25
Several Members of the House Committee on Agriculture submitted a letter to
EPA Administrator Stephen Johnson in July 2006 conveying support for the agency
to maintain its provision to exclude agriculture and mining dust and similar sources
of coarse particulates in the particulates NAAQS, as had been proposed.59 The EPA
indicated that with the exception of representatives of those sources that would have
been excluded under the proposal (e.g., agriculture and mining), most commenters
opposed the exclusion. Those opposed included environmental and public health
groups, state and local agencies, and industries not excluded from the proposed
indicator (e.g., transportation and construction).
The EPA did not exclude any areas or the types of particle in the final 2006
particulates NAAQS revisions, based on further consideration of the data and in
response to comments. In its rationale for the final PM standard, the EPA
10
continued to acknowledge that there is far more evidence concerning health effects
associated with thoracic coarse particles in urban areas than in non-urban areas.
However, the EPA also stated that “the existing evidence is inconclusive with regard
to whether or not community-level exposures to thoracic coarse particles are
associated with adverse health effects in non-urban areas.”60 The EPA indicated that
it is expanding its research and monitoring programs to collect additional evidence
on the differences between coarse particles typically found in urban areas and those
typically found in rural areas. The EPA announced the release of a final rule
amending its national air quality monitoring requirements on September 27, 2006.61
In contrast to objections regarding other aspects of EPA’s final 2006 particulates
NAAQS revisions, the CASAC agreed with the EPA decision against including
exemptions in its September 29, 2006, letter to the EPA Administrator. However,
a number of those representing agriculture interests, including some Members of
Congress, remain concerned that EPA’s decision not to include the exclusions in the
final 2006 particulates NAAQS will result in unnecessary burdens on the agricultural
community. During the 109th Congress, some Members of the House Committee on
Agriculture expressed their concerns with the EPA’s final actions with regard to the
exemptions at a September 28, 2006, hearing regarding the EPA’s pesticide
programs.62
Secondary PM and PM Standards
2.5
10
The EPA proposal, and the final 2006 particulates NAAQS, set the secondary
standard for PM and for PM at the same level as their primary standard. The PM
10
2.5
staff paper and the CASAC both recommended secondary standards at levels
59 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.
60 71 Federal Register 61143-61233, October 17, 2006, Section III.C.3. Decision Not to
Revise PM Indicator
, available at [http://epa.gov/pm/actions.html].
10
61 71 Federal Register 61236-61328, October 17, 2006, at [http://epa.gov/pm/actions.html].
62 House Committee on Agriculture, Subcommittee on Conservation, Credit, Rural
Development, and Research, Review of the Environmental Protection Agency’s Pesticide
Program
, September 28, 2006.

CRS-26
different from the primary in order to be more protective of visibility, and the
CASAC reiterated the recommendations in its March 21, 2006, and September 29,
2006, letters to the EPA Administrator. For PM , the EPA PM staff paper and most
2.5
of CASAC panel recommended consideration of a sub-daily standard with a level in
the range of 20 to 30 :g/m3 for a four- to eight-hour midday time period, with a 92nd
to 98th percentile form, as opposed to the primary daily standard at 35 µg/m3, based
on the current three-year average of the 98th percentile of 24-hour PM2.5
concentrations. Although the CASAC agreed with setting a secondary standard at
the same level as the primary standard based on the coarse particulates indicator
PM
, the committee recommended that the standard not be limited to urban areas,
10-2.5
as the EPA had proposed.
Exclusion of More Recent Research
A number of stakeholders commented that EPA should have considered certain
studies that were published too recently to have been included in the 2004 criteria
document that, they argued, increased the uncertainty about possible health risks
associated with exposure to particulates. Others contend that there are new studies
(some of them the same) in support of their arguments for a lower (more stringent)
level to protect health. Some commenters, opposed to more stringent standards,
argued that the agency should delay its decision regarding the PM NAAQS to take
into consideration several of these studies.
At the time of the proposal the EPA declared its intention to review and evaluate
significant new studies developed since 2002, and those published since the close of
the criteria document, during the comment period.63 With the release of its final 2006
particulates NAAQS, the EPA acknowledged that these studies provided expansion
of the science and some insights regarding particulates exposure and related health
effects, but determined that the new data “do not materially change any of the broad
scientific conclusions regarding the health effects of PM exposure made in the 2004
PM Air Quality Criteria Document.”64
Synopses of Stakeholder Reaction to the New 2006
Particulates NAAQS

Based on the EPA’s references to the comments in the preamble to the final
2006 particulates NAAQS revisions published October 17, 2006; a review of several
comments in the Federal Docket for the January 17, 2006, proposal; and several
media articles and available press releases, views of proponents and critics of stricter
standards are summarized below.
Proponents of more stringent particulates 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 PM staff
63 71 Federal Register 2625, January 17, 2006 ([http://epa.gov/pm/actions.html]).
64 71 Federal Register 61143-61233, October 17, 2006 ([http://epa.gov/pm/actions.html]).

CRS-27
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 is more compelling than
when the standards were revised in 1997;
! exclusion of rural sources from the coarse particle (PM ) standard
10
would not be 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; and
! welfare effects, such as visibility, crop yield, and forest health, will
be enhanced.
Critics of more stringent particulates standards contend that
! more stringent standards (and in some cases even the 1997
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 commenters identified as “urban” sources contend
exemption of rural particles may result in a disproportional
compliance burden;
! those identified as “rural” sources contend exemption of rural
particles is warranted by the lack of evidence regarding adverse
effects associated with emission sources in these areas, and that not
excluding these areas and sources creates an unnecessary burden;
! revising the standards could impede implementation of the existing
particulates 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
2004 and 2005, such as the Clean Air Interstate Rule (CAIR) and
Clean Air Nonroad Diesel Rule;65 and
65 70 Federal Register 25162, May 12, 2005, and 69 Federal Register 38958, June 29, 2004.
See also EPA’s website at [http://www.epa.gov/cleanair2004/].

CRS-28
! the benefits (and costs) associated with implementation of the 1997
PM NAAQS, as well as compliance with recent EPA air quality
2.5
regulations, have not yet been realized.
In late December 2006, 13 states (New York, California, Connecticut, Delaware,
Illinois, Maine, New Hampshire, New Jersey, New Mexico, Oregon, Pennsylvania,
Rhode Island, Vermont), the District of Columbia, and the South Coast Air Quality
Management District petitioned the U.S. Court of Appeals for the District of
Columbia Circuit to review the new 2006 particulates NAAQS.66 In addition, several
groups representing various industry and agriculture interests (including coal, iron,
steel, and corn refiners; oilseed processors; farmers; and cattle and pork producers,
as well as environmental and public health organizations) also filed petitions to the
court challenging the new 2006 NAAQS.
Conclusions
The EPA’s October 17, 2006, promulgation of the final modifications to the
existing particulates NAAQS following completion of its statutorily required review
has sparked interest and conflicting concerns among a diverse array of stakeholders,
and in Congress.
Tightening the particulates NAAQS will result in more areas classified as
nonattainment and needing to implement new controls on particulate matter. States
and local governments will 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 to be 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.
Because of health and cost implications, NAAQS decisions have been the
source of significant concern to some in Congress for quite some time. The
evolution and development of the particulates NAAQS, in particular, have been the
subject of extensive oversight. When the 1997 particulates NAAQS were
promulgated, Congress held 28 days of hearings on the EPA rule. Congress enacted
legislation specifying deadlines for implementation of the 1997 PM NAAQS,
2.5
funding for monitoring and research of potential health effects, and the coordination
of the particulates (and ozone) standard with other air quality regulations.
In late December 2006, several states and industry, agriculture, business,
environmental, and public health groups petitioned the Court of Appeals for the D.C.
Circuit to review the new 2006 particulates NAAQS. The EPA’s previous review
and establishment of particulates NAAQS were the subject of litigation and
66 Pursuant to Rule 15 of the Federal Rules of Appellate Procedure and §307(b) of the Clean
Air Act, 42 U.S.C. §7607(b).

CRS-29
challenges, including a Supreme Court decision in 2001.67 The EPA’s 1997
promulgation of standards for both coarse and fine particulate matter prompted critics
to charge the EPA with overregulation and spurred environmental groups to claim
that the EPA had not gone far enough. More than 100 plaintiffs petitioned the court
to overturn the standard.
Several elements of the EPA’s most recent action, including the level of
stringency of the new 2006 particulates NAAQS based on the supporting criteria, the
objections of the CASAC, the agency’s decision not to modify the particle size
indicator for coarse particulates, and not excluding rural sources from the coarse
standard as proposed have already generated debate and controversy. Thus, the final
form of the current efforts to revise PM NAAQS may not be known for some time.
67 American Trucking Ass’ns v. EPA, 175 F.3d 1027, 1055-56 (D.C. Cir. 1999), rehearing
granted in part and denied in part, 195 F.3d 4 (D.C. Cir. 1999), affirmed in part and reversed
in part, Whitman v. American Trucking Ass’ns, 531 U.S. 457 (2001). In March 2002, the
Court of Appeals rejected all remaining challenges to the standards, American Trucking
Ass’ns v. EPA
, 283 F. 3d 355, 369-72 (D.C. Cir. 2002).