Clean Air Issues in the 112th Congress
James E. McCarthy
Specialist in Environmental Policy
January 4, 2011
Congressional Research Service
7-5700
www.crs.gov
R41563
CRS Report for Congress
P
repared for Members and Committees of Congress

Clean Air Issues in the 112th Congress

Summary
Although air quality has improved substantially in the United States in the 40 years of EPA’s
Clean Air Act regulation, many issues remain unresolved, and, in recent months, members of
Congress from both parties have raised questions regarding the cost-effectiveness of, and
authority for, EPA actions. This report focuses on three general areas of likely interest to the 112th
Congress: greenhouse gas (GHG) regulations, emissions from power plants (including interstate
pollution and mercury emissions), and air quality standards.
EPA regulatory actions on GHG emissions using existing Clean Air Act authority have been the
main focus of congressional interest in clean air issues in recent months. Although the Obama
Administration and EPA spokespersons have consistently said that they would prefer that
Congress pass legislation to address climate change, EPA has begun to develop regulations using
its existing authority. On December 15, 2009, the agency finalized an “endangerment finding”
under Section 202 of the Clean Air Act, which requires it to regulate pollutants for their effect as
greenhouse gases for the first time. Relying on this finding, EPA finalized GHG emission
standards for cars and light trucks on April 1, 2010. The implementation of these standards will,
in turn, trigger permitting requirements and the imposition of Best Available Control Technology
for new major stationary sources of GHGs beginning in January 2011.
It is the triggering of standards for stationary sources (power plants, manufacturing facilities, etc.)
that has raised the most concern in Congress: legislation was introduced in both the House and
Senate in the 111th Congress—but not enacted—aimed at preventing EPA from implementing
these requirements, and similar legislation can be expected in the 112th. The legislation has taken
several forms, including resolutions of disapproval for EPA regulatory actions under the
Congressional Review Act, and stand-alone legislation that would forestall specific EPA
regulations. Meanwhile, EPA has itself promulgated regulations and guidance delaying the
applicability of requirements for stationary sources and focusing its regulatory efforts on the
largest emitters while granting smaller sources at least a six-year reprieve.
EPA’s GHG regulatory actions came as the 111th Congress struggled with climate change and
energy legislation. The House narrowly passed a bill establishing a comprehensive GHG
regulatory program (H.R. 2454), but comparable legislation (S. 1733 and S. 1462) did not reach
the Senate floor.
Besides addressing climate change, EPA has taken action on a number of air pollutant regulations,
generally in response to the courts. Several Bush Administration regulatory decisions were
vacated or remanded to the agency: among them, the Clean Air Interstate Rule (CAIR) and Clean
Air Mercury Rule—rules designed to control the long-range transport of sulfur dioxide, nitrogen
oxides, and mercury from power plants through cap-and-trade programs. EPA will address these
court decisions through new regulations—the agency proposed a replacement for CAIR July 6,
2010, and is expected to propose regulations for power plant emissions of mercury and other
hazardous air pollutants in March 2011. Some in Congress have wanted to address these issues
through legislation, an approach that might reduce the likelihood of further court challenges. The
agency is also in the midst of reviewing ambient air quality standards for the six most widespread
air pollutants. These standards serve as EPA’s definition of clean air, and drive a wide range of
regulatory controls.

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Contents
Introduction ................................................................................................................................ 1
EPA’s Greenhouse Gas Regulations ............................................................................................. 2
Legislation on Climate Change.................................................................................................... 5
Emissions from Power Plants ...................................................................................................... 6
Clean Air Interstate Rule (CAIR) .......................................................................................... 7
North Carolina v. EPA..................................................................................................... 7
Effects of the Decision .................................................................................................... 8
EPA’s CAIR Replacement: The Clean Air Transport Rule................................................ 8
Judicial and Legislative Options.................................................................................... 10
Clean Air Mercury Rule (CAMR) ....................................................................................... 10
Background .................................................................................................................. 10
New Jersey v. EPA......................................................................................................... 11
Other Mercury Issues .................................................................................................... 12
Next Steps..................................................................................................................... 12
Air Quality Standards................................................................................................................ 13
Background .................................................................................................................. 13
Judicial Reviews ........................................................................................................... 14
CASAC’s Role.............................................................................................................. 14
Adequacy of Monitoring ............................................................................................... 19
NAAQS Implementation............................................................................................... 19
Other Issues .............................................................................................................................. 20

Tables
Table 1. Status of NAAQS Reviews .......................................................................................... 16

Contacts
Author Contact Information ...................................................................................................... 20

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Introduction
EPA regulatory actions to limit greenhouse gas (GHG) emissions1 using existing Clean Air Act
authority have been the major focus of congressional interest in clean air issues in recent months.
Some Members, from both sides of the aisle, have expressed concern that EPA is proceeding with
regulations that could have major economic impacts without direct congressional authorization,
and/or that EPA should delay taking such action until Congress specifically authorizes it.
The Administration counters that it would prefer for Congress to pass new legislation to control
greenhouse gas emissions, but the Clean Air Act already requires action: a 2007 Supreme Court
decision interpreting EPA’s Clean Air Act authority found that the agency must weigh whether
GHG emissions endanger public health and welfare and, if it concludes that they do, proceed with
regulation.
The 111th Congress struggled to produce its own approach to climate change. In June 2009, the
House narrowly passed H.R. 2454, a 1,428-page bill addressing a number of interrelated energy
and climate change issues. Among its numerous provisions, the bill would have established cap-
and-trade programs for GHG emissions, beginning in 2012. The Senate did not act, however: two
Senate committees reported bills,2 but the prospect of obtaining 60 votes for either bill appeared
slim, and neither came to the floor. Toward the end of the second session, there was talk of a
slimmed-down bill focusing on energy and perhaps electric utilities, but even this limited
approach did not come to the floor.
A bipartisan group of Senators also considered addressing issues related to sulfur dioxide (SO2),
nitrogen oxides (NOx), and mercury emissions from electric power plants. Regulations
addressing these emissions were vacated by the D.C. Circuit Court of Appeals in 2008. EPA is
developing new regulations to address the court’s concerns. It proposed regulations addressing
SO2 and NOx on July 6, 2010; the agency is expected to propose regulations for power plant
emissions of mercury and other hazardous air pollutants, under a consent agreement, in March
2011. But legislation might provide a more straightforward solution, resolving ambiguities in
current law and reducing the likelihood of further delays from litigation. S. 2995, a bipartisan bill
addressing these issues, was introduced in the Senate during the 111th Congress and hearings were
held, but no further action was taken. Congress might consider similar legislation in the 112th.
The Obama Administration’s EPA has also moved to reconsider or modify several Bush
Administration decisions regarding national ambient air quality standards (NAAQS). NAAQS
represent EPA’s formal judgment regarding how clean the air must be to protect public health and
welfare; the standards set in motion monitoring and planning requirements, which in turn lead to
designation of “nonattainment areas” and the imposition of emission controls.
• On January 19, 2010, the agency proposed a more stringent NAAQS for ozone,
having concluded that a 2008 revision to the standard did not satisfy the

1 Six greenhouse gases, or groups of gases, are addressed by EPA regulatory actions: carbon dioxide (CO2), methane
(CH4), nitrous oxide (N2O), sulfur hexafluoride (SF6), hydrofluorocarbons (HFCs), and perfluorocarbons (PFCs). Of
these, carbon dioxide, produced by combustion of fossil fuels, is by far the most prevalent, accounting for 85% of
annual emissions of the combined group when measured as CO2 equivalents.
2 The Environment and Public Works Committee reported S. 1733, and the Energy and Natural Resources Committee
reported S. 1462.
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requirements of the Clean Air Act. The revision could affect as many as 650
counties—virtually every county that currently has an ozone monitor. Final
action on this proposal is expected in July 2011.
• On June 22, 2010, the agency promulgated revisions to the NAAQS for SO2; 59
counties would violate the new SO2 standard, based on the most recent
monitoring data.3 None violated the old standard.
• The agency is also reviewing or has recently completed reviews of the NAAQS
for four other pollutants, notably particulates, which are emitted by a wide range
of mobile and stationary sources. A revised particulate standard is to be proposed
by February 2011. Early indications are that the agency may propose
substantially more stringent standards.4
This report provides a brief overview of the climate change, power plant, and air quality standard
issues. More detailed information on most of the issues can be found in other CRS reports, which
are referenced throughout this report.
EPA’s Greenhouse Gas Regulations
EPA’s actions to regulate GHG emissions stem from more than a decade of petitions and
litigation. Responding to a 1999 petition that it regulate greenhouse gases from new motor
vehicles, the agency in 2003 denied that it had such authority, arguing that GHGs did not fall
within the Clean Air Act’s definition of “air pollutants.” The denial was challenged by
Massachusetts, 11 other states, and various other petitioners in a case that ultimately reached the
Supreme Court. In an April 2, 2007 decision (Massachusetts v. EPA), the Court found by 5-4 that
EPA does have authority to regulate greenhouse gas emissions, since the emissions are clearly air
pollutants under the Clean Air Act’s definition of that term.5 The Court’s majority concluded that
EPA must, therefore, decide whether emissions of these pollutants from new motor vehicles
contribute to air pollution that may reasonably be anticipated to endanger public health or
welfare. When it makes such an “endangerment finding,” the act requires the agency to establish
standards for emissions of the pollutants.
On December 15, 2009, acting in response to the Court’s decision, EPA finalized an
endangerment finding for greenhouse gas emissions from motor vehicles, under Section 202(a) of

3 The number of counties that will be formally designated nonattainment is likely to be different from the 59 EPA
identified, for two reasons. First, EPA promulgated changes to the monitoring requirements along with the new
standard. Second, the actual designations will most likely be made based on 2009-2011 monitoring data, whereas the
59 counties were identified using 2007-2009 data.
4 On July 2, 2010, EPA released the Second External Review Draft of its Policy Assessment for the Review of the
Particulate Matter NAAQS. The draft represented EPA staff’s recommendations to the Administrator. It outlined
options for revising both the fine and coarse particulate standard, both of which would make the standards more
stringent. The draft is available at http://www.epa.gov/ttn/naaqs/standards/pm/s_pm_2007_pa.html. Information on the
status of all of the NAAQS revisions can be found below in the section of this report entitled “Air Quality Standards.”
5 Massachusetts v. EPA, 549 U.S. 497 (2007). The majority held: “The Clean Air Act’s sweeping definition of ‘air
pollutant’ includes ‘any air pollution agent or combination of such agents, including any physical, chemical ...
substance or matter which is emitted into or otherwise enters the ambient air.... ‘ ... Carbon dioxide, methane, nitrous
oxide, and hydrofluorocarbons are without a doubt ‘physical [and] chemical ... substances[s] which [are] emitted into ...
the ambient air.’ The statute is unambiguous.” For additional discussion, see CRS Report RS22665, The Supreme
Court’s Climate Change Decision: Massachusetts v. EPA
, by Robert Meltz.
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the act.6 Relying on this finding, EPA promulgated GHG emission standards for new cars and
light trucks, April 1, 2010. The implementation of these standards will, in turn, trigger permitting
requirements and the imposition of Best Available Control Technology for new major stationary
sources of GHGs beginning in January 2011. (For information on these regulations and permit
requirements, see CRS Report R40506, Cars, Trucks, and Climate: EPA Regulation of
Greenhouse Gases from Mobile Sources
, and CRS Report R41212, EPA Regulation of
Greenhouse Gases: Congressional Responses and Options
.)
The prospect of GHG standards for motor vehicles is not particularly controversial. On May 19,
2009, President Obama announced an agreement involving nine U.S. and foreign auto
manufacturers; the federal government; the governors of California, Michigan, and
Massachusetts; the United Auto Workers; and environmental groups under which EPA and the
National Highway Traffic Safety Administration (NHTSA) would proceed with a joint
rulemaking in which GHG emissions from new motor vehicles would be reduced under the Clean
Air Act, while NHTSA would set corresponding fuel economy standards under the Corporate
Average Fuel Economy (CAFE) program.7 The objective of the new greenhouse gas standards is
to reach reduction levels similar to those adopted by the state of California and 13 other states,
who will harmonize their standards with those of EPA as part of the agreement. The California
standards required about a 30% reduction in GHG emissions from new vehicles by 2016. The
auto industry supported the national agreement, in part, to avoid having to meet standards on a
state-by-state basis; thus, it has not supported efforts to block EPA’s motor vehicle GHG
standards.
In addition to the motor vehicle GHG standards, EPA has received petitions asking the agency to
regulate GHGs from a variety of other sources, including coal mines, concentrated animal feeding
operations (CAFOs), aircraft, ocean-going ships, nonroad engines and equipment (e.g.,
construction equipment, farm equipment, recreational equipment, forklifts, harbor craft, and lawn
and garden equipment), and fuels. Another petition asks the agency to set National Ambient Air
Quality Standards for seven specific greenhouse gases. The agency also faces lawsuits seeking to
force it to regulate GHGs from stationary sources, including power plants, petroleum refineries,
nonroad vehicles and engines, and the Portland cement industry. The decision to move forward on
GHG standards for new motor vehicles is seen by many as a precedent for regulation of these
other sources.8 On December 23, 2010, EPA announced that it had reached a settlement
agreement with 11 states, the City of New York, the District of Columbia, and 3 environmental
groups under which it will propose GHG emission standards for power plants by July 26, 2011,

6 74 Federal Register 66496. While generally referred to as the “endangerment finding” (singular), the Federal
Register
notice consists of two separate findings: a Finding that Emissions of Greenhouse Gases Endanger Public
Health and Welfare, and a Finding that Greenhouse Gases From Motor Vehicles Cause or Contribute to the
Endangerment of Public Health and Welfare.
7 The President’s announcement and related documents, including a Notice of Upcoming Joint Rulemaking to Establish
Vehicle GHG Emissions and CAFE Standards, which appeared in the May 22, 2009 Federal Register, and both the
draft and final emission standards can be found at http://www.epa.gov/otaq/climate/regulations.htm. For additional
information, see CRS Report R40166, Automobile and Light Truck Fuel Economy: The CAFE Standards, by Brent D.
Yacobucci and Robert Bamberger or CRS Report R40506, Cars, Trucks, and Climate: EPA Regulation of Greenhouse
Gases from Mobile Sources
, by James E. McCarthy.
8 For a further discussion of these issues, see CRS Report R40984, Legal Consequences of EPA’s Endangerment
Finding for New Motor Vehicle Greenhouse Gas Emissions
, by Robert Meltz, CRS Report R40506, Cars, Trucks, and
Climate: EPA Regulation of Greenhouse Gases from Mobile Sources
, by James E. McCarthy, and CRS Report R40585,
Climate Change: Potential Regulation of Stationary Greenhouse Gas Sources Under the Clean Air Act, by Larry
Parker and James E. McCarthy.
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and for refineries by December 10, 2011, with promulgation by May 2012 and November 2012
respectively.
Even without EPA decisions on these petitions or the conclusion of lawsuits, the adoption of
GHG standards for motor vehicles has triggered GHG permit requirements for new stationary
sources, as a result of language in Section 165 of the act that requires such permits to require best
available control technology for all pollutants “subject to regulation” under the act. The permit
requirements began to take effect January 2, 2011. It is this triggering of standards for stationary
sources (power plants, manufacturing facilities, and others) that appears to have raised the most
concern in Congress: in the 111th Congress, legislation was introduced in both the House and
Senate aimed at preventing EPA from implementing these requirements. The legislation took
several forms, including:
• resolutions of disapproval for the endangerment finding itself under the
Congressional Review Act (S.J.Res. 26, H.J.Res. 66, H.J.Res. 76, and H.J.Res.
77);
• bills that would either have:
• required EPA to reevaluate its endangerment finding (H.Res. 974),
• amended the Clean Air Act to provide that greenhouse gases are not subject
to the act (H.R. 4396),
• limited EPA’s GHG authority to motor vehicle emissions (S. 1622), or
• suspended EPA actions regulating stationary source emissions of GHGs for
two years (S. 3072, H.R. 4753).
S.J.Res. 26, Senator Murkowski’s resolution of disapproval for the endangerment finding, was
defeated 53-47, on June 10, 2010. Meanwhile, EPA has itself promulgated regulations and
guidance that delayed the applicability of requirements for stationary sources of GHGs until 2011
and focused its initial permitting efforts on the largest emitters, granting smaller sources at least a
six-year reprieve.9
Although both the resolutions of disapproval and the stand-alone legislation to restrict EPA’s
authority have received a great deal of attention, the path to enactment of either of these forms of
legislation is a steep one. The Obama Administration has made the reduction of GHG emissions
one of its major goals; as a result, many conclude that legislation restricting EPA’s authority to
act, if passed by Congress, would encounter a presidential veto.
Addressing the issue through an amendment to the EPA appropriation, by cutting EPA’s
appropriation or by restricting its authority to use funds to take specific GHG regulatory actions,
might have more chance of enactment. The overall appropriation bill to which it would be
attached would presumably contain other elements that would make it more difficult to veto. This
approach was discussed at some length in the fall of 2009, when Senator Murkowski introduced

9 EPA has promulgated two rules that would have these effects: “Prevention of Significant Deterioration and Title V
Greenhouse Gas Tailoring Rule,” final rule, 75 Federal Register 31514, June 3, 2010; and “Reconsideration of
Interpretation of Regulations that Determine Pollutants Covered by Clean Air Act Permitting Programs,” final rule, 75
Federal Register 17004, April 2, 2010.
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(but ultimately did not offer) S.Amdt. 2530 to the FY2010 Interior, Environment, and Related
Agencies Appropriation Act (H.R. 2996).
In short, there are numerous ways that Congress can address EPA’s greenhouse gas authority, and
opponents of EPA action may continue to exert pressure to delay or limit the agency’s actions, as
the agency continues on its planned course. (For a more detailed discussion of EPA’s regulatory
actions and potential congressional responses, see CRS Report R41212, EPA Regulation of
Greenhouse Gases: Congressional Responses and Options
, by James E. McCarthy and Larry
Parker.)
Legislation on Climate Change
The 111th Congress also expended considerable time and effort considering comprehensive
legislation on energy use and emissions of greenhouse gases. The high water mark of this effort
was House passage of H.R. 2454, the American Clean Energy and Security Act of 2009, on June
26, 2009, by a vote of 219-212. The bill, also referred to by its acronym (ACES) or as the
Waxman-Markey bill, would have addressed a number of interrelated energy and climate change
issues. Among other provisions, it would have amended the Clean Air Act to establish a cap-and-
trade program10 (similar to the act’s current program for addressing acid rain) to limit greenhouse
gas (GHG) emissions beginning in 2012.11
The Senate Energy and Natural Resources Committee and the Senate Environment and Public
Works Committee reported Senate counterparts: S. 1462 (Bingaman), equivalent to the energy
titles, and S. 1733, the Kerry-Boxer bill, establishing a cap-and-trade system and other measures
to address climate change. The Kerry-Boxer bill faced strong opposition, however. The
Republican members of the Environment and Public Works Committee boycotted the markup.
The bill was reported with no Republican support and less than unanimous support among
Democrats: it was clear that the bill would lack the 60 votes necessary to overcome a filibuster
and secure passage on the floor. As a result, for about six months, negotiations took place among
a trio of Senators (Kerry, Graham, and Lieberman) for a bipartisan (or, more accurately,
tripartisan) alternative. This legislation, without Senator Graham’s sponsorship, circulated
extensively in draft form in 2010, but was not introduced. Ultimately, none of these bills reached
the Senate floor.
Legislation similar to the Waxman-Markey bill or the Kerry-Boxer bill is considered a nonstarter
in the 112th Congress. Republicans in the House were nearly unanimous in opposition to
Waxman-Markey in the 111th Congress, and many of the new Members ran in opposition to cap-
and-trade legislation. The slim majority that supported H.R. 2454 has almost certainly
disappeared, and the new leadership of the House is unanimous in opposition. Thus, EPA’s
regulatory actions (assuming they are not blocked by Congress) will be the principal U.S.
response to climate issues for now.

10 A cap-and-trade system sets a declining national cap on emissions and allocates emission allowances that can be
bought and sold on open markets. For additional information, CRS Report RL34513, Climate Change: Current Issues
and Policy Tools
, by Jane A. Leggett.
11 For a discussion of the bill’s provisions, see CRS Report R40145, Clean Air Issues in the 111th Congress, by James
E. McCarthy, pp. 4-12.
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Emissions from Power Plants
In addition to climate change, other clean air issues with a shorter time horizon are being
addressed by EPA and could be considered by Congress. Many of these have to do with emissions
from electric power plants.
Coal-fired power plants are among the largest sources of air pollution in the United States. Under
the Clean Air Act, however, they are not necessarily subject to stringent requirements: emissions
and the required control equipment can vary depending on the location of the plant, when it was
constructed, whether it has undergone major modifications, the specific type of fuel it burns, and,
to some extent, the vagaries of EPA enforcement policies. More than half a dozen separate Clean
Air Act programs could potentially be used to control emissions, which makes compliance
strategy complicated for utilities and difficult for regulators. Because the cost of the most
stringent available controls, for the entire industry, could range into the tens of billions of dollars,
utilities have fought hard and rather successfully to limit or delay regulations affecting them,
particularly with respect to plants constructed before the Clean Air Act of 1970 was passed.
As a result, emissions from power plants have not been reduced as much as those from some
other sources. Many plants built in the 1950s and 1960s (generally referred to as “grandfathered”
plants) have little emission control equipment.
Collectively, power plants are large sources of pollution. In 2005, they accounted for 10.2 million
tons of sulfur dioxide (SO2) emissions (70% of the U.S. total), 52 tons of mercury emissions
(46% of the U.S. total), and 3.6 million tons of nitrogen oxides (19% of the U.S. total). Power
plants are also considered major sources of fine particles (PM2.5), many of which form in the
atmosphere from emissions from a wide range of stationary and mobile sources. In addition,
power plants account for about 40% of U.S. anthropogenic emissions of the greenhouse gas
carbon dioxide.
With new ambient air quality standards for ozone, fine particles, and SO2 taking effect, emissions
of NOx and SO2 will necessarily have to be reduced to meet standards.12 (These standards are
discussed below under “Air Quality Standards.”) For more than a decade, mercury emissions
have also been a focus of concern. Mercury emitted by power plants and other sources is
deposited in water bodies and is taken up through the food chain: 48 states have issued fish
consumption advisories due to mercury pollution, covering 14 million acres of lakes, 882,000
river miles, and the coastal waters of 13 entire states. The continuing controversy over the
interpretation of New Source Review requirements for existing power plants (which require the
installation of Best Available Control Technology whenever an existing power plant undergoes
major modifications) has exerted pressure for a more predictable regulatory structure, as well.
Thus, some in industry, environmental groups, Congress, and the last two Administrations have
said that legislation addressing power plant pollution in a comprehensive (multi-pollutant)
fashion would be desirable. Such legislation would address the major pollutants on a coordinated
schedule and would rely, to a large extent, on a system such as the one used in the acid rain
program, where national or regional caps on emissions are implemented through a system of

12 NOx contributes to the formation of ozone and fine particles; SO2, besides being a regulated pollutant in its own
right, is among the sources of fine particles.
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tradable allowances. The key questions have been how stringent the caps should be and whether
carbon dioxide (CO2), the major gas of concern with regard to climate change, would be among
the emissions subject to a cap.
Clean Air Interstate Rule (CAIR)
The Senate Environment and Public Works Committee has voted twice on a multi-pollutant bill
(in 2002 and 2005), but neither of the bills progressed to the Senate floor. In the House, similar
bills have been introduced, but none has progressed to markup. On March 10, 2005, therefore,
EPA announced that it would use existing Clean Air Act authority to promulgate final regulations
similar to the Bush Administration’s multi-pollutant bill (the “Clear Skies” bill13) for utility
emissions of SO2 and NOx in 28 eastern states and the District of Columbia.14
The Clean Air Interstate Rule (CAIR) established cap-and-trade provisions for SO2 and NOx.15
CAIR covered only the eastern half of the country, but since most of the grandfathered generation
capacity is located in the East and South, EPA projected that nationwide emissions of SO2 would
decline 53% by 2015 and NOx emissions 56%.16 The agency also projected that the rule would
result in $85-$100 billion in health benefits annually by 2015, including the annual prevention of
17,000 premature deaths. CAIR’s health and environmental benefits would be more than 25 times
greater than its costs, according to EPA.
North Carolina v. EPA
CAIR was one of the few Bush Administration environmental initiatives that was generally
supported by environmentalists. It also had broad support in the regulated community. But a
variety of petitioners, including the state of North Carolina, which argued that the rule was not
strong enough to address pollution from upwind sources, and some individual utilities that felt
they were unfairly treated by the rule’s emission budgets, challenged the rule in the D.C. Circuit,
and the court vacated it July 11, 2008. A unanimous court found that EPA had established a
“significant contribution” made by power plants to nonattainment of standards and failure to
maintain standards in downwind states, as required by Section 110 of the Clean Air Act, but the
court concluded that the agency’s methodology for establishing emission budgets for each state
was unrelated to that contribution.17 The court also found that the choice of 2015 for a second
phase compliance deadline, based on technological and economic feasibility, ignored EPA’s
statutory mandate. It found the fuel adjustment factors in the rule (which set more stringent

13 President Bush first proposed the Clear Skies Act on February 14, 2002, and the bill was introduced by request in the
107th Congress as H.R. 5266/S. 2815. In the 109th Congress, a somewhat modified Clear Skies bill, introduced as S.
131, was considered by the Environment and Public Works Committee, but failed to advance, on a 9-9 vote. Clear
Skies was not introduced in the 110th Congress.
14 The rule appeared in the Federal Register two months later. See U.S. EPA, “Ambient air quality standards,
national—Fine particulate matter and ozone; interstate transport control measures,” 70 Federal Register 25162, May
12, 2005.
15 A separate regulation, the Clean Air Mercury Rule (CAMR), promulgated at the same time, established a Clear-
Skies-like cap-and-trade system for mercury emissions. It is described in a separate section below.
16 As compared to nationwide emissions from electric generating units in 2001. Some of the projected reduction would
be due to pre-existing regulations. See U.S. EPA, Office of Air and Radiation, Regulatory Impact Analysis for the Final
Clean Air Interstate Rule
, March 2005, pp. 3-3 and 3-4, at http://www.epa.gov/cair/pdfs/finaltech08.pdf.
17 North Carolina v. EPA, 531 F.3d 896 (D.C. Cir. 2008).
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requirements for natural gas- and oil-fired plants than for coal-fired ones) to be arbitrary and
capricious. It concluded: “CAIR’s flaws are deep. No amount of tinkering ... will transform
CAIR, as written, into an acceptable rule.”18
Despite the seemingly high hurdle set by the language the court used, EPA, environmental
groups, and the utility and mining industries asked the court to review its decision. On December
23, 2008, the court modified its decision, allowing CAIR to remain in effect until a new rule is
promulgated by EPA. 19 The court was not specific about how long this process would be allowed
to take, but stated:
Though we do not impose a particular schedule by which EPA must alter CAIR, we remind
EPA that we do not intend to grant an indefinite stay of the effectiveness of this court’s
decision. Our opinion revealed CAIR’s fundamental flaws, which EPA must still remedy.20
Effects of the Decision
There is general agreement among the states, electric utilities, and environmental groups that
something like CAIR should be salvaged.
• Without CAIR, most eastern states would have huge gaps in their emission
control programs, which would have to be filled by other regulatory measures if
the states are to attain the NAAQS by the statutory deadlines. The states could be
subject to Clean Air Act sanctions, including a suspension of federal highway
funding for new projects, if they fail to adopt such measures.
• For the utilities, CAIR was designed to build on the existing regulatory
framework of cap-and-trade programs under the acid rain program and the “NOx
SIP Call.”21 Anticipating the ability to bank and trade emission allowances under
CAIR, numerous utilities have already invested in equipment to meet or exceed
CAIR’s requirements, the first phase of which are now being implemented.
• For environmental groups, which found little to their liking in the Bush
Administration, CAIR was the major exception. They argued for a stronger
version of CAIR—particularly its second phase, to be implemented in 2015—but
they generally supported the basic approach.
EPA’s CAIR Replacement: The Clean Air Transport Rule
On July 6, 2010, EPA proposed a replacement for CAIR, the Clean Air Transport Rule.22 The
transport rule would leave the CAIR Phase 1 limits in place and would set new limits replacing
CAIR’s second phase in 2012 and 2014, up to three years earlier than CAIR would have.

18 Id. at 930.
19 North Carolina v. EPA, 550 F.3d 1176 (D.C. Cir. 2008).
20 Ibid.
21 The acid rain program, established by the Clean Air Act Amendments of 1990, established a cap-and-trade program
for sulfur dioxide emissions from electric generating units. Implementation began in 1995. The NOx SIP Call,
implemented in 2004, is a cap-and-trade program for control of nitrogen oxide emissions in the eastern half of the
country.
22 The proposal appeared in the Federal Register August 2, 2010. The rule, a Fact Sheet, a Regulatory Impact Analysis,
(continued...)
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The CAIR Phase 1 rules already appear to be having substantial effects. On August 11, 2010, EPA
reported that emissions of SO2 had declined sharply in both 2008 and 2009: in the latter year,
emissions from fossil-fueled power plants in the lower 48 states (at 5.7 million tons) were 44%
below 2005 levels. NOx emissions from the same sources declined to 1.8 million tons in 2009, a
decline of 45% compared to 2005.23 Further reductions of both SO2 and NOx can be expected as
Phase 1 takes effect.
The proposed transport rule would build on these reductions. It would establish a second and third
phase of reductions in 2012 and 2014, with particular emphasis on SO2—emissions of which
would decline to 3.8 million tons (62% below 2005 levels) in 2014. The proposed rule would
cover 31 Eastern, Midwestern, and Southern states and the District of Columbia, adding three
new states (Oklahoma, Kansas, and Nebraska) to the 28 covered by CAIR. The rule would allow
unlimited trading of allowances within individual states, but it would limit interstate trading in
order to comply with the D.C. Circuit’s ruling. In order to insure that the rule is implemented
quickly, EPA proposed a Federal Implementation Plan (FIP) for each of the states: the FIP
specifies emission budgets for each state based on controlling emissions from electric power
plants. States may develop their own State Implementation Plans and choose to control other
types of sources if they wish, but the federal plan will take effect until the state acts to replace it.
EPA estimates that the rule will cost the power sector $2.8 billion annually in 2014, but it expects
the benefits to be 40 to 100 times as great—an estimated $120 billion to $290 billion annually.
The most important benefit would be 14,000 to 36,000 fewer premature deaths annually. Avoided
deaths and other benefits occur throughout the East, Midwest, and South, according to EPA, with
Ohio, Pennsylvania, and New York benefitting the most.24
Because the agency is near finalizing more stringent ambient air quality standards for ozone (as
discussed below in the Air Quality Standards section of this report), it stated its intention to
propose another transport rule in the summer of 2011 to address any additional emission
reductions needed to meet those new standards. It also stated an “ongoing commitment” to
consider upwind contributions of pollution to nonattainment when implementing any future
NAAQS revisions. With revisions of the fine particulate (PM2.5) standard expected by fall 2011,
additional transport rules might be expected.
State air pollution control agencies, through the National Association of Clean Air Agencies
(NACAA), have argued that substantial further reductions will be necessary if the states are to
attain the new ozone standards. Ozone forms through chemical reactions in the atmosphere
between volatile organic compounds and NOx; after decades of focus on VOC reductions, NOx
reductions are key to attaining a more stringent ozone standard. For NOx, the Phase 1 cap is 45%
below baseline, with Phase 2 providing an additional 7%. The control technology is clearly
available to do more: EPA modeling projects 34% of coal-fired electric generating units in the
transport region to be without the best available NOx control in 2014.25 Assuming that modeling

(...continued)
and an overview presentation can be found on EPA’s website at http://www.epa.gov/airtransport/actions.html#jul10.
23 Data are from EPA’s “2009 Acid Rain Program Emission and Compliance Data Report,” August 11, 2010, at
http://www.epa.gov/airmarkets/progress/ARP09.html.
24 U.S. EPA, Office of Air and Radiation, “Proposed Air Pollution Transport Rule,” Overview Presentation, July 26,
2010, pp. 13-15, at http://www.epa.gov/airtransport/pdfs/TRPresentationfinal_7-26_webversion.pdf.
25 U.S. EPA, Office of Air and Radiation, Regulatory Impact Analysis for the Proposed Federal Transport Rule, June
2010, Table 7-11, p. 259, http://www.epa.gov/ttn/ecas/regdata/RIAs/proposaltrria_final.pdf. The technology referred to
(continued...)
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shows that more reductions are needed for the states to attain the new ozone NAAQS, the
pressure will be on EPA to strengthen the regulations further.
Judicial and Legislative Options
The courts might be the venue for further consideration of the issues if any of the parties find
themselves unhappy with the pace or substance of EPA’s regulatory decisions.
Congress might also act. In order to shorten the regulatory process and avoid further litigation,
some have argued that Congress needs to resolve the issues posed by the D.C. Circuit’s 2008
CAIR decision. Over the past decade, several dozen multi-pollutant bills would have addressed
SO2 and NOx emissions from power plants through a cap-and-trade system, most of them in
conjunction with controls on mercury and CO2. If legislation were to be considered now, the
issues might, therefore, include not only the stringency and timing of SO2 and NOx controls, but
also whether to include mercury and CO2 controls in the bill.
In the 111th Congress, on February 4, 2010, Senators Carper and Alexander, with a bipartisan
group of cosponsors, introduced S. 2995 to address the issues posed by the CAIR decision and to
set standards for power plant mercury emissions. The bill would have established cap-and-trade
systems for SO2 and NOx with more stringent caps than those of the CAIR rule or EPA’s
proposed replacement. The SO2 cap would be 78% below the 2001 baseline in 2015, and 83%
below in 2018. The EPA Administrator would have been authorized to reduce the cap further for
2021 and later years. The NOx cap would also have been more stringent than provided by CAIR
or the proposed transport rule and it would cover 32 states (seven more than CAIR, four more
than the proposed EPA rule). In 2012, its cap would be 24% below CAIR’s emissions level (in
addition to covering more states within that cap). In 2015, its cap would be identical to CAIR’s,
but because it would cover seven more states, would still be more stringent on a state-by-state
basis. The bill would also have established a NOx cap in the rest of the lower 48 states for the
first time, which would decline 37% by 2020.
At a Senate hearing, March 4, 2010, there was general support for S. 2995, although some
concern was expressed that the reductions would still not be sufficient to bring Eastern states into
attainment of the ozone NAAQS.26
Clean Air Mercury Rule (CAMR)
Background
Mercury is a potent neurotoxin that can cause adverse health effects (principally delayed
development, neurological defects, and lower IQ in fetuses and children) at very low
concentrations.27 The principal route of exposure to mercury is through consumption of fish.

(...continued)
is selective catalytic reduction (SCR).
26 “Legislative Hearing: S. 2995, The Clean Air Act Amendments of 2010,” U.S. Senate Committee on Environment
and Public Works, March 4, 2010. See especially the testimony of Colin P. O’Mara, Secretary, Delaware Department
of Natural Resources and Environmental Control.
27 For a discussion of mercury’s health effects, see CRS Report RL32420, Mercury in the Environment: Sources and
(continued...)
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Mercury enters water bodies, often through air emissions, and is taken up through the food chain,
ultimately affecting humans as a result of fish consumption. As noted earlier, 48 states have
issued fish consumption advisories due to mercury pollution, covering 14 million acres of lakes,
882,000 river miles, and the coastal waters of 13 entire states. Electric generating units account
for about half of U.S. mercury emissions.
Regulation of mercury emissions from coal-fired power plants has a complicated legislative and
regulatory history, dating back to the 1990 Clean Air Act Amendments. EPA was required by that
legislation and a 1998 consent agreement to determine whether regulation of mercury from power
plants under Section 112 of the Clean Air Act was appropriate and necessary. Section 112 is the
section that regulates emissions of hazardous air pollutants. In general, it requires EPA to set
standards based on the Maximum Achievable Control Technology (a term defined with great
precision in the act), and to impose the MACT standards at each individual emissions source. In a
December 2000 regulatory finding, EPA concluded that regulation of mercury from power plants
under Section 112 was appropriate and necessary. The finding added coal- and oil-fired electric
generating units to the list of sources of hazardous air pollutants, and triggered other provisions of
the 1998 consent agreement: the agency was to propose MACT standards for them by December
15, 2003, and finalize the standards by March 15, 2005.
Rather than promulgate MACT standards, however, EPA reversed its December 2000 finding in
March 2005, and established through regulations a national cap-and-trade system for power plant
emissions of mercury, the Clean Air Mercury Rule (CAMR). Under CAMR, the final cap would
have been 15 tons of emissions nationwide in 2018 (about a 70% reduction from 1999 levels,
when achieved). There would also have been an intermediate cap of 38 tons in 2010, well above
EPA’s projection of emissions in that year.28
Under the cap-and-trade system, utilities could either control the pollutant directly or purchase
excess allowances from other plants that instituted controls more stringently or sooner than
required. As with the acid rain and CAIR cap-and-trade programs, early reductions under CAMR
could have been banked for later use, which the agency itself said would result in utilities
delaying compliance with the full 70% reduction until well beyond 2018, as they used up banked
allowances rather than installing further controls. The agency’s analysis projected actual
emissions to be 24.3 tons (less than a 50% reduction) as late as 2020. Full compliance with the
70% reduction would have been delayed until after 2025.29 (For additional information on the
mercury rule, see CRS Report RL32868, Mercury Emissions from Electric Power Plants: An
Analysis of EPA’s Cap-and-Trade Regulations
, by James E. McCarthy.)
New Jersey v. EPA
The CAMR rule was challenged in petitions for review filed by New Jersey and 16 other states as
well as other petitioners.30 The D.C. Circuit, in a 3-0 decision handed down February 8, 2008,31

(...continued)
Health Risks, by Linda-Jo Schierow.
28 The agency projected emissions at 31 tons in 2010 even if 99% of the generating units installed no mercury control
equipment.
29 U.S. EPA, Mercury RIA, previously cited, Table 7-3, p. 7-5.
30 Seven other states joined EPA in defending the rule.
31 New Jersey v. EPA, 517 F.3d 574 (D.C. Cir. 2008).
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vacated the rule. The court found that once the agency had listed electric generating units (EGUs)
as a source of hazardous air pollutants, it had to proceed with MACT regulations under Section
112 of the act unless it “delisted” the source category, under procedures the act sets forth in
Section 112(c)(9). Delisting would have required the agency to find that no EGU’s emissions
exceeded a level adequate to protect public health with an ample margin of safety, and that no
adverse environmental effect would result from any source—a difficult test to meet, given the
agency’s estimate that EGUs are responsible for 46% of mercury emissions from all U.S. sources.
Rather than delist the EGU source category, the agency had maintained that it could simply
reverse its December 2000 “appropriate and necessary” finding, a decision that was much simpler
because there were no statutory criteria to meet. The court found this approach unlawful. “This
explanation deploys the logic of the Queen of Hearts, substituting EPA’s desires for the plain text
of Section 112(c)(9),” the court said in its opinion.32
Other Mercury Issues
Besides the question of whether EPA complied with the law’s requirements, critics found other
reasons to oppose EPA’s cap-and-trade approach to controlling mercury. One of the main
criticisms has been that it would not address “hot spots,” areas where mercury emissions and/or
concentrations in water bodies are greater than elsewhere. In fact, under a cap-and-trade system,
nothing would prevent emissions from increasing at hot spots. Many also argued that the mercury
regulations should have been more stringent or implemented more quickly than the cap-and-trade
regulations would have required. These arguments found a receptive audience in the states: about
20 states have promulgated requirements stricter than the federal program, with several requiring
80% to 90% mercury reductions before 2010. (For additional information, see archived CRS
Report RL33535, Mercury Emissions from Electric Power Plants: States Are Setting Stricter
Limits
, by James E. McCarthy.)
Next Steps
Under the D.C. Circuit’s ruling, unless EPA delists the power plant category, it does not have the
legislative authority to establish a cap-and-trade program for their mercury emissions: it must
impose MACT standards on each individual plant once it has listed the category. The agency
could have appealed the court’s ruling: under the Bush Administration, on October 17, 2008, it
petitioned for certiorari to the Supreme Court.33 But the Obama Administration withdrew the
petition in early February 2009 and announced that it will proceed with the development of
MACT standards.34 Proposed standards are expected, under a consent agreement, by March 2011,
with final standards to be promulgated in November 2011.
While the agency develops new regulations in response to the court’s remand, new coal-fired
electric generating units and modifications of existing units are required to obtain permits under a
provision of the law known as the “MACT hammer” (Section 112(g)(2)). Under this provision, if
no applicable emission limits have been established, no person may construct a new major source
or modify an existing major source in the category unless the Administrator or the state

32 Id. at 582.
33 77 U.S.LW 3253 (No. 08-512).
34 Withdrawal of EPA’s petition for certiorari left a separate petition filed by the Utility Air Regulatory Group before
the Court. The Court denied that petition, February 23, 2009.
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determines on a case-by-case basis that they meet MACT emission limits. On February 28, 2008,
the Natural Resources Defense Council (NRDC) released a list of 32 new coal-fired power plants
in 13 states that it believed must adopt MACT mercury controls under this provision.35
Air Quality Standards
Background
Air quality has improved substantially since the passage of the Clean Air Act in 1970: annual
emissions of the six most widespread (“criteria”) air pollutants36 have declined nearly 180 million
tons (59%), despite major increases in population, motor vehicle miles traveled, and economic
activity.37 Nevertheless, the goal of clean air continues to elude many areas, in part because
scientific understanding of the health effects of air pollution has caused EPA to tighten standards
for most of the criteria pollutants. Congress anticipated that the understanding of air pollution’s
effects on public health and welfare would change with time, and it required, in Section 109(d) of
the act, that EPA review the standards at five-year intervals and revise them, as appropriate.
The most widespread problems involve ozone and fine particles. As of September 2010, 119
million people lived in areas classified “nonattainment” for the ozone National Ambient Air
Quality Standard (NAAQS);38 70 million lived in areas that were nonattainment for the fine
particle (PM2.5) NAAQS.39 EPA attributes at least 33,000 premature deaths and millions of lost
work days annually to exceedances of the PM2.5 standard. Recent research has tied ozone
pollution to premature mortality as well.
Violations of the ambient air quality standards for the other four criteria pollutants are not as
widespread, but EPA is engaged in (or has recently completed) reviews indicating that health
effects of most of these pollutants are more serious than previously thought. At present, for
example, no areas exceed the NAAQS for sulfur dioxide (SO2), but in a recent review, EPA
determined that between 2,300 and 5,900 premature deaths can be avoided annually by
strengthening that standard. Thus, the agency has promulgated a new SO2 standard under which

35 NRDC, “32 Coal-Fired Power Plants in 13 States Now Up in the Air After Major Court Ruling on Mercury,” Press
Release, February 28, 2008, at http://www.nrdc.org/media/2008/080228.asp.
36 The six criteria air pollutants are ozone, particulate matter, sulfur dioxide, carbon monoxide, nitrogen dioxide, and
lead. Criteria pollutants, identified by the EPA Administrator, are pollutants that (a) cause or contribute to air pollution
which may reasonably be anticipated to endanger public health or welfare, and (b) the presence of which in the ambient
air results from numerous or diverse mobile or stationary sources (Section 108(a)(1) of the Clean Air Act).
37 See U.S. EPA, “Air Emissions Summary Through 2005,” at http://www.epa.gov/air/airtrends/2006/
emissions_summary_2005.html, updated with data from 2008 in U.S. EPA, “Air Quality Trends,” at
http://www.epa.gov/airtrends/aqtrends.html#comparison. The six criteria pollutants are ozone, particulate matter,
carbon monoxide, sulfur dioxide, nitrogen oxides, and lead.
38 Data for ozone nonattainment areas are from the U.S. EPA “Green Book,” at http://www.epa.gov/oar/oaqps/greenbk/
gntc.html.
39 Fine particles, as defined by EPA, consist of particulate matter 2.5 micrometers or less in diameter, abbreviated as
PM2.5. Data for PM2.5 nonattainment areas are also from the U.S. EPA “Green Book,” at http://www.epa.gov/oar/oaqps/
greenbk/qntc.html.
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as many as 59 counties could be designated nonattainment, based on the most recent monitoring
data.40
Table 1 summarizes EPA’s recent efforts to review the NAAQS and implement revisions,
including the next steps for each of the six criteria pollutants. Revisions for five of the six
pollutants (ozone, PM, lead, NO2, and SO2) have been completed since 2006, with the standards
being made more stringent in each case (three of the five were subsequently challenged in court
and two of these three were remanded to the agency for further revisions). Reviews of the
NAAQS for carbon monoxide and the two remanded standards (ozone and PM) are to be
completed in 2010 or 2011.41
Judicial Reviews
As the table indicates, court challenges have played a key role in bringing about the NAAQS
reviews, and in causing further review after the NAAQS have been promulgated. Reviews of
most of the standards were stimulated at least in part by court cases: EPA is statutorily required to
review the NAAQS every five years, and its failure to do so can be addressed by citizen suits.
At the other end of the process, once the agency’s review of a NAAQS is completed, the
standards are almost invariably challenged in court. In the case of both particulate matter and
ozone, judicial review has led to a remand of the standards that EPA promulgated in 2006 and
2008 respectively. The agency has now agreed to promulgate further revisions to these standards
in 2011.
CASAC’s Role
In making his decisions regarding the 2008 ozone and 2006 particulate standards, then-EPA
Administrator Stephen Johnson did not follow the advice of the agency’s independent science
advisors, the Clean Air Scientific Advisory Committee (CASAC). The Administrator is not
required by statute to follow CASAC’s recommendations; the act requires only that he set forth in
the Federal Register notice in which he (or she) proposes a NAAQS any pertinent findings,
recommendations, and comments made by CASAC and, if the proposal differs in an important
respect from any of the recommendations, provide an explanation of the reasons for such
differences.42 But the failure to follow CASAC recommendations almost inevitably raises the
question of whether the Administrator’s decision will be judged arbitrary and capricious in a
judicial review.
In the recent revisions of both the ozone and PM standards, CASAC made detailed objections to
the Administrator’s final decisions. The committee’s description of the process as having failed to
meet statutory and procedural requirements could play an important role during judicial review.

40 http://www.epa.gov/air/sulfurdioxide/pdfs/20100602map0709.pdf. The 59 potential nonattainment counties were
identified using the most recent available monitoring data (2007-2009). EPA is likely to use 2009-2011 or later data
when it comes time to actually designate the areas. Additional monitors will also be sited.
41 There are CRS reports on three of the NAAQS revisions: CRS Report R41062, Ozone Air Quality Standards: EPA’s
Proposed Revisions
, CRS Report RL34762, The National Ambient Air Quality Standards (NAAQS) for Particulate
Matter (PM): EPA’s 2006 Revisions and Associated Issues
, and CRS Report RL34479, Revising the National Ambient
Air Quality Standard for Lead
.
42 The requirement is found in Section 307(d)(3) of the act.
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This raises the question of whether Congress might reconsider CASAC’s statutory role in the
review process, or further specify the conditions under which the Administrator may reject
CASAC’s advice.
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Table 1. Status of NAAQS Reviews
Monitoring
Pollutant
Last Revision
Court Action?
Next Steps
Issues?
Comments
ozone
March 27, 2008;
In response to
Final standards
Only 675 of the
March 2008
revised
suits filed by 15
are expected to
nation’s 3,000
primary (health-
(for additional
standards were
states (Mississippi be promulgated
counties have
based) standards
information, see
proposed
v. EPA), EPA
by the end of
ozone monitors: were set at a
CRS Report
January 19, 2010. agreed to
July, 2011.
Between 515
level less
R41062, Ozone
reconsider the
Implementation
and 650 of these stringent than
Air Quality
March 2008
of the 2008
counties
recommended
Standards: EPA’s
standards.
NAAQS is
exceeded the
by EPA’s science
Proposed
stayed pending
proposed
advisers. The
Revisions, by
review.
standard based
revision also did
James E.
on the most
not act on
McCarthy)
recent
proposed
monitoring data.
changes to the
Ozone is
form of the
increasingly seen secondary
as a regional
(welfare)
pol utant that
standard that
affects rural as
would have
well as urban
more accurately
areas, so more
addressed
counties may
impacts on crops
need monitors.
and forests. The
On July 14, 2009, January 2010
EPA proposed to proposal
require that
addresses both
states monitor
of these issues.
ozone
concentrations
in rural as well
as urban areas.
particulate
October 17,
The D.C. Circuit EPA expects to
Environmental
October 2006
matter (PM2.5
2006
remanded the
propose a PM2.5
groups would
primary
and PM10)
2006 PM2.5
NAAQS by
like to see
standards for
standards to EPA February 2011,
additional
PM
(for additional
2.5 were set at
in February 2009 with promulga-
monitoring in
levels less
information, see
(American Farm
tion of final
areas with
stringent than
CRS Report
Bureau Federation standards by
expected high
recommended
RL34762, The
v. EPA).
October 2011.
concentrations
by EPA’s science
National Ambient
(e.g., along
advisers.
Air Quality
In an agency
highways, near
Standards
document
ports, etc.).
(NAAQS) for
released July 2,
Particulate Matter
2010, staff
(PM): EPA’s 2006
recommended
Revisions and
substantially
Associated Issues,
more stringent
by Robert
standards.
Esworthy and
James E.
McCarthy)
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Monitoring
Pollutant
Last Revision
Court Action?
Next Steps
Issues?
Comments
sulfur dioxide
On June
The D.C. Circuit EPA intends to
The current SO2 Since 1971, EPA
(SO2)
22,2010, EPA
remanded the
designate
monitoring
had conducted
revised the
SO2 standard to
nonattainment
network is not
three reviews of
NAAQS,
EPA in 1998,
areas by June
primarily
the SO2 standard
focusing on
following an
2012.
configured to
without changing
shorter-term
agency review
monitor
it.
(1-hour)
that left the
locations of
exposures. The
standard
maximum short-
prior standards
unchanged. The
term
(for 24-hour and court found the
concentrations.
annual
Administrator
The network
concentrations),
had failed
needs 41 new
which were
adequately to
monitoring sites,
revoked as part
explain her
according to
of the revision,
conclusion that
EPA. In a change
were set in
no public health
from the
1971. The new
threat existed
agency’s
short-term
from short term
December 2009
standard is
exposures to
proposal, EPA
substantially
SO2. (American
will rely
more stringent,
Lung Association
primarily on
replacing a 24-
v. EPA)
dispersion
hour standard of
modeling to
140 parts per
assess
billion (ppb) with
compliance with
a 1-hour
the standard.
maximum of 75
ppb.
carbon
Current primary
The U.S. District EPA must
Uncertain. Emissions
of
monoxide (CO)
standard was set Court for the
propose any
CO, largely from
in 1971. EPA
Northern
revision to the
motor vehicles,
revoked a
District of
CO NAAQS by
have declined
secondary
California has
January 28, 2011,
56% since 1980,
standard in 1985. ordered EPA to
with final action
and few areas
review the CO
by August 12,
violate the
NAAQS by May
2011.
existing CO
13, 2011.
NAAQS.
(Communities for
a Better
Environment v.
EPA)
nitrogen dioxide
EPA completed a A suit filed in
EPA expects to
Under EPA’s
There are no
(NO2)
review and
2005 charged
identify
new monitoring
nonattainment
promulgated a
that EPA had
nonattainment
network, a
areas for the
new 1-hour
failed to review
areas by January
monitor will be
annual standard,
standard
the NO2
2012. However,
required near a
and only Cook
February 9,
standard in the
the agency
major road in
County, IL
2010. The new
last 5 years, as
believes most
any urban area
(Chicago)
standard is in
required by the
areas will be
with a
violates the new
addition to the
Clean Air Act
“unclassifiable,”
population of
1-hour standard
previous annual
(Center for
due to the lack
350,000 or
using current
average
Biological Diversity of adequate
more. (The
monitoring data.
standard, which
v. Johnson).
monitoring.
majority of NO2
NO2 emissions
was set in 1971. Under a 2007
Once an
emissions come
have been more
consent decree,
expanded
from motor
stringently
EPA proposed
network of NO2 vehicles.)
controlled even
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Monitoring
Pollutant
Last Revision
Court Action?
Next Steps
Issues?
Comments
revisions to the
monitors is fully
Community-
though there
primary standard deployed and
wide
have not been
July 15, 2009,
three years of air concentrations
recent violations
and promulgated quality data have would also be
of the NO2
the revisions in
been collected,
monitored in
standard,
February 2010.
the agency will
urban areas with because nitrogen
redesignate
populations of
oxides
areas (in 2016 or 1,000,000 or
contribute to the
2017) based on
more.
formation of
air quality data
ozone, the
from the new
standard for
monitoring
which has been
network.
reviewed and
strengthened
several times.
lead
November 12,
Both
Revised
In July 2009, EPA EPA’s November
2008
environmental
monitoring rules agreed to review 2008 action
(for additional
groups (which
were proposed
the monitoring
reduced the
information, see
challenged the
December 23,
portions of its
standard by 90%,
archived CRS
adequacy of the
2009.
November 2008
from 1.5
Report RL34479,
monitoring
NAAQS. At
micrograms per
Revising the
requirements)
The lawsuit
least 24 of the
cubic meter
National Ambient
and industry
challenging the
50 states,
(μg/m3) to 0.15
Air Quality
(which
standard itself is
including some
μg/m3.
Standard for
challenged the
proceeding.
with major
Environmental
Lead, by James E.
standard itself)
sources of lead
groups, while
McCarthy)
Sixteen
have petitioned
nonattainment
emissions, had
general y pleased
for review
areas were
no lead monitors with the
(Missouri Coalition designated in
at all. Under the
NAAQS itself,
for the
November 2010. 2008 regulations, petitioned for
Environment v.
101 metro areas reconsideration
EPA and Coalition
(those with
of the
of Battery
populations
monitoring
Recyclers
greater than
requirements,
Association v.
500,000) would
arguing that EPA
EPA). EPA
be required to
should require
granted a
have monitors as more locations
petition for
would an
near emission
reconsideration
estimated 135
sources to have
of the
areas that have
monitors.
monitoring
sources of lead
Industry groups
requirements in
emissions
believe the
July 2009.
greater than or
standard itself is
equal to one ton too stringent.
per year.
Proposed
regulations
would lower the
source threshold
to 0.5 tons.


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Adequacy of Monitoring
A feature common to many of the recent NAAQS reviews has been EPA’s finding that the current
monitoring network is inadequate to determine whether or not many areas of the country are in
attainment of the standards. In several cases, such as for lead and sulfur dioxide, more extensive
monitoring networks had been partly dismantled by the time the standards were reviewed, after
years of indicating compliance with older, less stringent standards.43 In other cases, such as PM
and NO2, the monitoring network was not designed to measure the kinds of exposure that current
research identifies as a cause of concern (e.g., exposure to fine particles near highways). As a
result, EPA and the states will need to devote resources in the next few years to expanding and
refocusing the monitoring networks in order to identify areas where air quality does not meet new
standards.
NAAQS Implementation
Although most of the NAAQS standards are likely to have been revised by the end of 2011—
ultimately stimulating billions of dollars in expenditures on pollution control—the impact of the
new standards will be gradual. A NAAQS does not directly limit emissions; rather, a primary
NAAQS represents the Administrator’s formal judgment regarding the level of ambient pollution
below which public health will be protected with an adequate margin of safety; a secondary
standard reflects her judgment as to the level of ambient pollution necessary to protect public
welfare, including protection of the environment, water quality, building materials, etc.
Promulgation of a NAAQS sets in motion a lengthy process under which states and the EPA first
identify nonattainment areas. Those areas then undertake a complicated implementation process.
The first step, designation of nonattainment areas, generally takes at least two years after a
standard is promulgated, and in many cases longer, if a new monitoring network needs to be
established. After nonattainment areas are formally designated, the states generally have three
years to submit State Implementation Plans (SIPs) that identify the specific regulations and
emission control requirements that will bring the area into attainment.
Whether more stringent NAAQS will lead to stronger federal emission controls for the sources of
pollution—in addition to the controls contemplated by individual states or metropolitan areas—is
likely to be an important issue. Several of the criteria pollutants have impacts across state lines,
far from the source of emissions; others (notably ozone) form in the atmosphere as the result of
chemical reactions involving precursors that may have been emitted many miles upwind. Thus,
measures taken by individual states and nonattainment areas to control emissions within their
borders may be inadequate for the areas to attain a NAAQS. Federal standards for cars, trucks,
power plants, and other major pollution sources could need strengthening for many areas to be
able to attain the NAAQS.
Congress has given EPA the authority to strengthen such emission standards; but Congress may
still act to review the implementation of that authority.

43 Also, reductions in EPA grants to the states in some years may have resulted in the elimination of some monitoring
stations. EPA has concluded in some cases that modeling using data from remaining monitors could fill in data gaps.
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Clean Air Issues in the 112th Congress

Other Issues
Over the past two years, EPA has proposed and promulgated numerous regulations implementing
the Clean Air Act (and other pollution control statutes that it administers). Critics of the
Administration, both within Congress and outside of it, have accused the agency of reaching
beyond the authority given it by Congress and ignoring or underestimating the costs and
economic impacts of these rules. House Republican leaders have promised vigorous oversight of
the agency in the 112th Congress, and attempts to overturn specific regulations or limit the
agency’s authority are widely expected. Particular attention may be paid to the Clean Air Act,
under which (as noted in “EPA’s Greenhouse Gas Regulations” above) EPA has moved forward
with the first federal controls on emissions of greenhouse gases. But attention has also been
directed at regulations addressing criteria or hazardous air pollutants from a number of industries
and at the revisions of the National Ambient Air Quality Standards discussed in the previous
section of this report.
One of the regulations that has attracted the most attention is the Maximum Achievable Control
Technology standards for boilers (the “Boiler MACT”) proposed June 4, 2010. Boilers are used
as power sources throughout industry and for power or heat by large commercial establishments
and institutions. EPA estimates that the rule, as proposed, would provide $17 billion to $41 billion
in benefits annually, including the avoidance of 1,900 to 4,800 premature deaths; but it would
also impose annualized costs of $2.9 billion, according to the agency. As a result, there is
widespread interest in the proposed rule’s requirements and their potential effects. (For a detailed
discussion, see CRS Report R41459, EPA’s Boiler MACT: Controlling Emissions of Hazardous
Air Pollutants
, by James E. McCarthy.) Other Clean Air Act rules (for the Portland cement
industry and for emissions from stationary engines, among others) have also attracted discussion.
Environmental groups disagree that the agency has overreached, and EPA itself maintains that its
pace of regulation under the Clean Air Act is actually slower than the pace during the first years
of the Clinton and George W. Bush Administrations. The agency states that critics’ focus on the
cost of controls obscures the benefits of new regulations, which, it estimates, far exceed the costs;
and it maintains that pollution control is an important source of economic activity, exports, and
American jobs.
For a discussion of EPA’s regulatory actions, both under the Clean Air Act and under other
statutes, see CRS Report R41561, EPA Regulations: Too Much, Too Little, or On Track?

Author Contact Information

James E. McCarthy

Specialist in Environmental Policy
jmccarthy@crs.loc.gov, 7-7225


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