Clean Air Act: A Summary of the Act and
Its Major Requirements

James E. McCarthy
Specialist in Environmental Policy
Claudia Copeland
Specialist in Resources and Environmental Policy
Larry Parker
Specialist in Energy and Environmental Policy
Linda-Jo Schierow
Specialist in Environmental Policy
January 6, 2011
Congressional Research Service
7-5700
www.crs.gov
RL30853
CRS Report for Congress
P
repared for Members and Committees of Congress

Clean Air Act: A Summary of the Act and Its Major Requirements

Summary
This report summarizes the Clean Air Act and its major regulatory requirements. It excerpts, with
minor modifications, the Clean Air Act chapter of CRS Report RL30798, Environmental Laws:
Summaries of Major Statutes Administered by the Environmental Protection Agency
, which
summarizes a dozen environmental statutes that form the basis for the programs of the
Environmental Protection Agency. This report will be updated at the end of each Congress, or
sooner if Congress enacts a law that substantively changes the statute.
The principal statute addressing air quality concerns, the Clean Air Act was first enacted in 1955,
with major revisions in 1970, 1977, and 1990. The Act requires EPA to set health-based standards
for ambient air quality, sets deadlines for the achievement of those standards by state and local
governments, and requires EPA to set national emission standards for large or ubiquitous sources
of air pollution, including motor vehicles, power plants, and other industrial sources. In addition,
the Act mandates emission controls for sources of 187 hazardous air pollutants, establishes a cap-
and-trade program to limit acid rain, requires the prevention of significant deterioration of air
quality in areas with clean air, requires a program to restore visibility impaired by regional haze
in national parks and wilderness areas, and implements the Montreal Protocol to phase out most
ozone-depleting chemicals.
This report describes the Act’s major provisions and provides tables listing all major amendments,
with the year of enactment and Public Law number, and cross-referencing sections of the Act
with the major U.S. Code sections of the codified statute.

Congressional Research Service

Clean Air Act: A Summary of the Act and Its Major Requirements

Contents
Introduction ................................................................................................................................ 1
Overview .................................................................................................................................... 1
National Ambient Air Quality Standards...................................................................................... 3
State Implementation Plans ......................................................................................................... 3
Nonattainment Requirements ...................................................................................................... 4
Requirements for Ozone Nonattainment Areas ...................................................................... 5
Requirements for Carbon Monoxide Nonattainment Areas .................................................... 7
Requirements for Particulate Nonattainment Areas ................................................................ 7
Transported Air Pollution ............................................................................................................ 8
Emission Standards for Mobile Sources....................................................................................... 8
Hazardous Air Pollutants........................................................................................................... 10
New Source Performance Standards .......................................................................................... 12
Solid Waste Incinerators............................................................................................................ 12
Prevention of Significant Deterioration / Regional Haze............................................................ 12
Acid Deposition Control ........................................................................................................... 13
Permits ..................................................................................................................................... 15
Enforcement ............................................................................................................................. 15
Stratospheric Ozone Protection ................................................................................................. 16
Selected References .................................................................................................................. 17

Tables
Table 1. Clean Air Act and Amendments ..................................................................................... 2
Table 2. Ozone Nonattainment Classifications ............................................................................. 5
Table 3. Major U.S. Code Sections of the Clean Air Act ............................................................ 18

Contacts
Author Contact Information ...................................................................................................... 24

Congressional Research Service

Clean Air Act: A Summary of the Act and Its Major Requirements

Introduction
The authorities and responsibilities of the Environmental Protection Agency (EPA) derive
primarily from a dozen major environmental statutes. This report provides a concise summary of
one of those statutes, the Clean Air Act. It provides a very brief history of federal involvement in
air quality regulation and of the provisions added by legislation in 1970, 1977, and 1990; it
explains major authorities contained in the Act; it defines key terms; and it lists references for
more detailed information on the Act and its implementation.
While this report attempts to present the essence of the Act, it is necessarily incomplete. Many
details and secondary provisions are omitted. In addition, the report describes the statute largely
without discussing its implementation. Statutory deadlines to control emissions and achieve
particular mandates have often been missed as a result of delayed standard-setting by EPA,
delayed action on implementation by states and local governments, or law suits brought by
interested parties. Other CRS products, including CRS Report R41563, Clean Air Issues in the
112th Congress
, by James E. McCarthy, and more than a dozen other CRS reports, discuss
implementation concerns and current issues. Readers interested in a more comprehensive
discussion of the history of the Act are referred to CRS Report 83-34, Environmental Protection:
An Historical Review of the Legislation and Programs of the Environmental Protection Agency

(available by request).
Overview
The Clean Air Act, codified as 42 U.S.C. 7401 et seq., seeks to protect human health and the
environment from emissions that pollute ambient, or outdoor, air. It requires the Environmental
Protection Agency to establish minimum national standards for air quality, and assigns primary
responsibility to the states to assure compliance with the standards. Areas not meeting the
standards, referred to as “nonattainment areas,” are required to implement specified air pollution
control measures. The Act establishes federal standards for mobile sources of air pollution and
their fuels and for sources of 187 hazardous air pollutants, and it establishes a cap-and-trade
program for the emissions that cause acid rain. It establishes a comprehensive permit system for
all major sources of air pollution. It also addresses the prevention of pollution in areas with clean
air and protection of the stratospheric ozone layer.
Like many other programs administered by the Environmental Protection Agency, federal efforts
to control air pollution have gone through several phases, beginning with information collection,
research, and technical assistance, before being strengthened to establish federal standards and
enforcement. Federal legislation addressing air pollution was first passed in 1955, prior to which
air pollution was the exclusive responsibility of state and local levels of government.
The federal role was strengthened in subsequent amendments, notably the Clean Air Act
Amendments of 1970, 1977, and 1990. The 1970 amendments established the procedures under
which EPA sets national standards for air quality, required a 90% reduction in emissions from
new automobiles by 1975, established a program to require the best available control technology
at major new sources of air pollution, established a program to regulate air toxics, and greatly
strengthened federal enforcement authority. The 1977 amendments adjusted the auto emission
standards, extended deadlines for the attainment of air quality standards, and added the
Prevention of Significant Deterioration program to protect air cleaner than national standards.
Congressional Research Service
1

Clean Air Act: A Summary of the Act and Its Major Requirements

Table 1. Clean Air Act and Amendments
(codified generally as 42 U.S.C. 7401-7671)
Year
Act
Public Law Number
1955
Air Pol ution Control Act
P.L. 84-159
1959 Reauthorization
P.L.
86-353
1960
Motor vehicle exhaust study
P.L. 86-493
1963
Clean Air Act Amendments
P.L. 88-206
1965
Motor Vehicle Air Pol ution Control Act
P.L. 89-272, Title I
1966
Clean Air Act Amendments of 1966
P.L. 89-675
1967
Air Quality Act of 1967
P.L. 90-148
National Air Emission Standards Act
1970
Clean Air Act Amendments of 1970
P.L. 91-604
1973 Reauthorization
P.L.
93-13
1974
Energy Supply and Environmental Coordination Act of 1974
P.L. 93-319
1977
Clean Air Act Amendments of 1977
P.L. 95-95
1980
Acid Precipitation Act of 1980
P.L. 96-294, Title VII
1981
Steel Industry Compliance Extension Act of 1981
P.L. 97-23
1987
Clean Air Act 8-month Extension
P.L. 100-202
1990
Clean Air Act Amendments of 1990
P.L. 101-549
1991
Technical correction to list of hazardous air pollutants
P.L. 102-187
1995-96 Relatively minor laws amending the Act
P.L. 104-6, 59, 70, 260
1998
Amended § 604 re methyl bromide
P.L. 105-277, Section 764
1998
Border Smog Reduction Act of 1998
P.L. 105-286
1999
Chemical Safety Information, Site Security and Fuels Regulatory P.L. 106-40
Relief Act
2004
Amendments to §209 re smal engines
P.L. 108-199, Division G, Title IV,
Section 428
2005
Energy Policy Act of 2005 (amended §211 re fuels)
P.L. 109-58
2007
Energy Independence and Security Act of 2007 (amended §211
P.L. 110-140
re fuels)
Changes to the Act in 1990 included provisions to (1) classify most nonattainment areas
according to the extent to which they exceed the standard, tailoring deadlines, planning, and
controls to each area’s status; (2) tighten auto and other mobile source emission standards; (3)
require reformulated and alternative fuels in the most polluted areas; (4) revise the air toxics
section, establishing a new program of technology-based standards and addressing the problem of
sudden, catastrophic releases of air toxics; (5) establish an acid rain control program, with a
marketable allowance scheme to provide flexibility in implementation; (6) require a state-run
permit program for the operation of major sources of air pollutants; (7) implement the Montreal
Protocol to phase out most ozone-depleting chemicals; and (8) update the enforcement provisions
so that they parallel those in other pollution control acts, including authority for EPA to assess
administrative penalties.
Congressional Research Service
2

Clean Air Act: A Summary of the Act and Its Major Requirements

The 1990 amendments also authorized appropriations for clean air programs through FY1998.
The Act has not been reauthorized since then. House rules require enactment of an authorization
before an appropriation bill can be considered; but this requirement can be waived and frequently
has been. Thus, while authorization of appropriations in the Clean Air Act (and most other
environmental statutes) has expired, programs have continued and have been funded. The Act’s
other legal authorities, to issue and enforce regulations, are, for the most part, permanent and are
not affected by the lack of authorization.
The remainder of this report describes major programs required by the Act, with an emphasis on
the changes established by the 1990 amendments.
National Ambient Air Quality Standards
In section 109, the Act requires EPA to establish National Ambient Air Quality Standards
(NAAQS) for air pollutants that endanger public health or welfare, in the Administrator’s
judgment, and whose presence in ambient air results from numerous or diverse sources. The
NAAQS must be designed to protect public health and welfare with an adequate margin of safety.
Using this authority, EPA has promulgated NAAQS for six air pollutants: sulfur dioxide (SO2),
particulate matter (PM2.5 and PM10), nitrogen dioxide (NO2), carbon monoxide (CO), ozone,1 and
lead. The Act requires EPA to review the scientific data upon which the standards are based, and
revise the standards, if necessary, every five years. More often than not, however, EPA has taken
more than five years in reviewing and revising the standards.
Originally, the Act required that the NAAQS be attained by 1977 at the latest, but the states
experienced widespread difficulty in complying with this deadline. As a result, the deadlines for
achieving NAAQS have been extended several times. Under the 1990 amendments, most areas
not in attainment with NAAQS must meet special compliance schedules, staggered according to
the severity of an area’s air pollution problem. The amendments also established specific
requirements for each nonattainment category, as described below.
State Implementation Plans
While the Act authorizes the EPA to set NAAQS, the states are responsible for establishing
procedures to attain and maintain the standards. Under Section 110 of the Act, the states adopt
plans, known as State Implementation Plans (SIPs), and submit them to EPA to ensure that they
are adequate to meet statutory requirements.
SIPs are based on emission inventories and computer models to determine whether air quality
violations will occur. If these data show that standards would be exceeded, the state must impose
additional controls on existing sources to ensure that emissions do not cause “exceedances” of the
standards. Proposed new and modified sources must obtain state construction permits in which
the applicant shows how the anticipated emissions will not exceed allowable limits. In

1 Unlike the other NAAQS pollutants, ozone is not directly emitted, but rather is formed in the atmosphere by the
interaction of volatile organic compounds (VOCs) and nitrogen oxides (NOx) in the presence of sunlight. The control
of ozone is, thus, based on regulating emissions of VOCs and NOx.
Congressional Research Service
3

Clean Air Act: A Summary of the Act and Its Major Requirements

nonattainment areas, emissions from new or modified sources must also be offset by reductions in
emissions from existing sources.
The 1990 amendments require EPA to impose sanctions in areas which fail to submit a SIP, fail to
submit an adequate SIP, or fail to implement a SIP: unless the state corrects such failures, a 2-to-1
emissions offset for the construction of new polluting sources is imposed 18 months after
notification to the state, and a ban on most new federal highway grants is imposed six months
later. An additional ban on air quality grants is discretionary. Ultimately, a Federal
Implementation Plan may be imposed if the state fails to submit or implement an adequate SIP.
The amendments also require that, in nonattainment areas, no federal permits or financial
assistance may be granted for activities that do not “conform” to a State Implementation Plan.
This requirement can cause a temporary suspension in funding for most new highway and transit
projects if an area fails to demonstrate that the emissions caused by such projects are consistent
with attainment and maintenance of ambient air quality standards. Demonstrating conformity of
transportation plans and SIPs is required in nonattainment areas whenever new plans are
submitted.
Nonattainment Requirements
In a major departure from the prior law, the 1990 Clean Air Act Amendments grouped most
nonattainment areas into classifications based on the extent to which the NAAQS was exceeded,
and established specific pollution controls and attainment dates for each classification. These
requirements are described here as spelled out in Sections 181-193 of the Act.2
Nonattainment areas are classified on the basis of a “design value,” which is derived from the
pollutant concentration (in parts per million or micrograms per cubic meter) recorded by air
quality monitoring devices. The design value for the 1-hour ozone standard was the fourth highest
hourly reading measured during the most recent three-year period. Using these design values, the
Act created five classes of ozone nonattainment, as shown in Table 2. Only Los Angeles fell into
the “extreme” class, but 97 other areas were classified in one of the other four ozone categories. A
simpler classification system established moderate and serious nonattainment areas for carbon
monoxide and particulate matter with correspondingly more stringent control requirements for the
more polluted class.

2 EPA modified the ozone standard, specified in the statute as 0.12 parts per million (ppm) averaged over a 1-hour
period, to 0.08 ppm averaged over an 8-hour period, through regulations promulgated in July 1997. In April 2004, the
agency promulgated an implementation rule for the new 8-hour standard. Under this rule, the 1-hour standard was
revoked as of June 15, 2005, and areas that had not yet attained it were converted to new classifications depending on
their 8-hour concentration of ozone. As a result of court challenges, the ramifications of this conversion to the 8-hour
standard are still unfolding, but in general the former 1-hour nonattainment areas remain subject to the controls
specified for their 1-hour category. New nonattainment areas that did not exceed the 1-hour standard, but do violate the
8-hour standard, in general are subject to more flexible controls under Subpart 1 (Sections 171-179B) of the act. The
standard was revised again in March 2008, to 0.075 ppm averaged over 8 hours, but EPA subsequently agreed to
reconsider the 2008 standard, a task it expects to complete in 2011. Nonattainment areas for the new standard would be
designated following its promulgation.
Congressional Research Service
4

Clean Air Act: A Summary of the Act and Its Major Requirements

Table 2. Ozone Nonattainment Classifications
Class Marginal Moderate Serious Severe Extreme
Deadline 1993 1996 1999
2005-2007a 2010
Areasb
42 areas
32 areas
14 areas
9 areas
1 area
Design
0.121 ppm-
0.138 ppm-
0.160 ppm-
0.180 ppm-
Value
0.138 ppm
0.160 ppm
0.180 ppm
0.280 ppm
>0.280 ppm
a. Areas with a 1988 design value between 0.190 and 0.280 ppm have 17 years to attain; others have 15 years.
b. Number of areas in each category as of the date of enactment.
As shown in the table, the deadlines for attainment for ozone nonattainment areas stretched from
1993 to 2010, depending on the severity of the problem. (Under the 8-hour ozone standard, which
replaced the 1-hour standard in 2004, these deadlines are changed to 2007 to 2021.) For carbon
monoxide, the attainment date for moderate areas was December 31, 1995, and for serious areas,
December 31, 2000. For particulate matter, the deadline for areas designated moderate
nonattainment as of 1990 was December 31, 1994; for those areas subsequently designated as
moderate, the deadline is six years after designation. For serious areas, the respective deadlines
are December 31, 2001 or 10 years after designation.
Requirements for Ozone Nonattainment Areas
Although areas with more severe air pollution problems have a longer time to meet the standards,
more stringent control requirements are imposed in areas with worse pollution. A summary of the
primary ozone control requirements for each nonattainment category follows.
Marginal Areas
• Inventory emissions sources (to be updated every three years).
• Require 1.1 to 1 offsets (i.e., new major emission sources of volatile organic
compounds [VOCs] must reduce VOC emissions from existing facilities in the
area by 10% more than the emissions of the new facility).
• Impose reasonably available control technology (RACT) on all major sources
emitting more than 100 tons per year for the nine industrial categories where EPA
had already issued control technique guidelines describing RACT prior to 1990.
Moderate Areas
• Meet all requirements for marginal areas.
• Impose a 15% reduction in VOC emissions in six years.
• Adopt a basic vehicle inspection and maintenance program.
• Impose RACT on all major sources emitting more than 100 tons per year for all
additional industrial categories where EPA will issue control technique guidelines
describing RACT.
• Require vapor recovery at gas stations selling more than 10,000 gallons per
month.
• Require 1.15 to 1 offsets.
Congressional Research Service
5

Clean Air Act: A Summary of the Act and Its Major Requirements

Serious Areas
• Meet all requirements for moderate areas.
• Reduce definition of a major source of VOCs from emissions of 100 tons per
year to 50 tons per year for the purpose of imposing RACT.
• Reduce VOCs 3% annually for years 7 to 9 after the 15% reduction already
required by year 6.
• Improve monitoring.
• Adopt an enhanced vehicle inspection and maintenance program.
• Require fleet vehicles to use clean alternative fuels.
• Adopt transportation control measures if the number of vehicle miles traveled in
the area is greater than expected.
• Require 1.2 to 1 offsets.
• Adopt contingency measures if the area does not meet required VOC reductions.
Severe Areas
• Meet all requirements for serious areas.
• Reduce definition of a major source of VOCs from emissions of 50 tons per year
to 25 tons per year for the purpose of imposing RACT.
• Adopt specified transportation control measures.
• Implement a reformulated gasoline program.
• Require 1.3 to 1 offsets.
• Impose $5,000 per ton penalties on major sources if the area does not meet
required reductions.
Extreme Areas
• Meet all requirements for severe areas.
• Reduce definition of a major source of VOCs from emissions of 25 tons per year
to 10 tons per year for the purpose of imposing RACT.
• Require clean fuels or advanced control technology for boilers emitting more
than 25 tons per year of NOx.
• Require 1.5 to 1 offsets.
As noted, EPA promulgated a new, 8-hour ozone standard in July 1997. Following extensive court
challenges, the agency designated nonattainment areas for the new standard on April 30, 2004.
State Implementation Plans were required to be submitted in 2007.
Congressional Research Service
6

Clean Air Act: A Summary of the Act and Its Major Requirements

Requirements for Carbon Monoxide Nonattainment Areas
As with ozone nonattainment areas, carbon monoxide (CO) nonattainment areas are subjected to
specified control requirements, with more stringent requirements in Serious nonattainment areas.
A summary of the primary CO control requirements for each nonattainment category follows.
Moderate Areas
• Conduct an inventory of emissions sources.
• Forecast total vehicle miles traveled in the area.
• Adopt an enhanced vehicle inspection and maintenance program.
• Demonstrate annual improvements sufficient to attain the standard.
Serious Areas
• Adopt specified transportation control measures.
• Implement an oxygenated fuels program for all vehicles in the area.
• Reduce definition of a major source of CO from emissions of 100 tons per year
to 50 tons per year if stationary sources contribute significantly to the CO
problem.
Serious areas failing to attain the standard by the deadline have to revise their SIP and
demonstrate reductions of 5% per year until the standard is attained.
Requirements for Particulate Nonattainment Areas
Particulate (PM10) nonattainment areas are also subject to specified control requirements. These
are:
Moderate Areas
• Require permits for new and modified major stationary sources of PM10.
• Impose reasonably available control measures (RACM).
Serious Areas
• Impose best available control measures (BACM).
• Reduce definition of a major source of PM10 from 100 tons per year to 70 tons
per year.
In July 1997, EPA promulgated new standards for fine particulates (PM2.5). The PM2.5 standards
were also subject to court challenges. The absence of a monitoring network capable of measuring
the pollutant delayed implementation as well. Nonattainment areas for PM2.5 were designated on
April 14, 2005. States had three years subsequent to designation to submit State Implementation
Plans. Revisions to the NAAQS promulgated in October 2006 strengthened the PM2.5 standard.
Congressional Research Service
7

Clean Air Act: A Summary of the Act and Its Major Requirements

Transported Air Pollution
Meeting the nation’s clean air standards can be complicated as air pollution is no respecter of
political boundaries or subdivisions. This problem of transported air pollutants has come into
particular focus as states and EPA attempt to develop effective compliance strategies to achieve
both the ozone and the PM2.5 NAAQS. Under Section 110(a)(2)(D), SIPs must include adequate
provisions to prevent sources within that state from contributing significantly to nonattainment in
one or more downwind states.
If EPA finds a SIP inadequate to achieve a NAAQS, it must require the affected state to submit a
revised SIP that includes sufficient measures to bring that state into compliance. This is known as
a “SIP Call.” The 1990 Clean Air Act amendments provided EPA and the states with new tools to
address the transport problem through this provision. One of those tools is Section 176A, a
provision that permits the EPA, either on its own or by petition from any state, to establish a
transport region to address regional pollution problems contributing to violations of a primary
NAAQS. A commission of EPA and state officials is constituted to make recommendations to
EPA on appropriate mitigation strategies. Based on the commission’s findings and
recommendations, EPA is then required under section 110(k)(5) to notify affected states of
inadequacies in their current state implementation plans and to establish deadlines (not to exceed
18 months) for submitting necessary revisions (i.e., a SIP call). Besides authorizing
administratively-created transport regions, the 1990 amendments statutorily created an Ozone
Transport Region (OTR) in the Northeast. This provision (Section 184 of the act) required
specific additional controls for all areas (not only nonattainment areas) in that region, and
established the Ozone Transport Commission for the purpose of recommending to EPA
regionwide controls affecting all areas in the region.
The transport issue may also be addressed by affected downwind states through a Section 126
petition. As amended by the 1990 Clean Air Act amendments, under Section 126(b) any state or
political subdivision may petition EPA for a finding that a major source or group of stationary
sources located in another state is emitting pollutants that “significantly contribute” to the
nonattainment of a NAAQS by their state. EPA is to respond to the petition within 60 days. If the
petition is granted, the offending sources must cease operations within three months unless the
sources comply with emission controls and the compliance schedules as determined by EPA to
bring them into compliance with the section. Section 126 has rarely been used, although it has
proven useful to EPA in some cases as backup authority where there might be challenges to a SIP
call.
Emission Standards for Mobile Sources
Title II of the Clean Air Act has required emission standards for automobiles since 1968. The
1990 amendments significantly tightened these standards: for cars, the hydrocarbon standard was
reduced by 40% and the nitrogen oxides (NOx) standard by 50%. These standards—referred to as
“Tier 1” standards—were phased in over the 1994-1996 model years.
The amendments envisioned a further set of reductions (“Tier 2” standards), but not before model
year 2004. For Tier 2 standards to be promulgated, the agency was first required to report to
Congress concerning the need for further emission reductions, the availability of technology to
achieve such reductions, and the cost-effectiveness of such controls compared to other means of
Congressional Research Service
8

Clean Air Act: A Summary of the Act and Its Major Requirements

attaining air quality standards. EPA submitted this report to Congress in August 1998, concluding
that further emission reductions were needed and that technology to achieve such reductions was
available and cost-effective. Tier 2 standards, requiring emission reductions of 77% to 95% from
cars and light trucks were promulgated in February 2000, and were phased in over the 2004-2009
model years. To facilitate the use of more effective emission controls, the standards also require a
more than 90% reduction in the sulfur content of gasoline, beginning in 2004.
The 1990 amendments also required that oxygenated gasoline, designed to reduce emissions of
carbon monoxide, be sold in the worst CO nonattainment areas and that “reformulated” gasoline
(RFG), designed to reduce emissions of volatile organic compounds and toxic air pollutants, be
sold in the nine worst ozone nonattainment areas (Los Angeles, San Diego, Houston, Baltimore,
Philadelphia, New York, Hartford, Chicago, and Milwaukee); metropolitan Washington, DC; and
four areas in California were added to the mandatory list later. Other ozone nonattainment areas
can opt in to the RFG program; as of 2006, additional areas in 11 states had done so.
The fuels provisions were modified by the Energy Policy Act of 2005 (EPACT), removing the
requirement that RFG contain oxygenates. Instead, EPACT required the use of increasing
amounts of renewable fuel, most likely to be ethanol, in motor fuels, beginning in 2006. The
Energy Independence and Security Act of 2007 further strengthened the renewable fuel
requirements.
Use of alternative fuels and development of cleaner engines was also to be stimulated by the
Clean-Fuel Fleet Program. In all of the most seriously polluted ozone and CO nonattainment
areas, centrally fueled fleets of 10 or more passenger cars and light-duty trucks must purchase at
least 30% clean-fuel vehicles when they add new vehicles to existing fleets, starting in 1999. (The
Act originally required the program to begin in 1998, but the start was delayed by a year.) The
percentage rose to 50% in 2000 and 70% in 2001. Heavy-duty fleets are required to purchase at
least 50% clean-fuel vehicles annually. A clean fuel vehicle is one which meets Low Emission
Vehicle (LEV) standards and operates on reformulated gasoline, reformulated diesel, methanol,
ethanol, natural gas, liquefied petroleum gas, hydrogen, or electricity.
In addition to the above program, California’s Zero Emission Vehicle (ZEV) program also is
intended to promote the development of alternative fuels and vehicles. Section 209(b) of the
Clean Air Act allows the EPA Administrator to grant California the authority to develop its own
vehicle emissions standards if those standards are at least as stringent as the federal standards and
if the state demonstrates that it needs the standards to meet compelling and extraordinary
conditions. In addition to setting more stringent standards for all vehicles, California used this
authority to establish a program requiring auto manufacturers to sell ZEVs (electric or hydrogen
fuel cell vehicles) in the state beginning in 2003. This program has been substantially modified
since it was enacted, and now allows credit for hybrid and partial ZEV vehicles in addition to true
ZEVs, but it has served as an incubator for lower emission technologies since its adoption.
Section 177 of the Act allows other states to adopt California’s stricter standards: at least ten
states (Connecticut, Maine, Massachusetts, New Jersey, New York, Oregon, Pennsylvania, Rhode
Island, Vermont, and Washington) have already adopted them or are in the process of doing so.
The 1990 amendments also imposed tighter requirements on certification (an auto’s useful life is
defined as 100,000 miles instead of the earlier 50,000 miles), on emissions allowed during
refueling, on low temperature CO emissions, on in-use performance over time, and on warranties
for the most expensive emission control components (8 years/80,000 miles for the catalytic
Congressional Research Service
9

Clean Air Act: A Summary of the Act and Its Major Requirements

converter, electronic emissions control unit, and onboard emissions diagnostic unit). Regulations
were also extended to include nonroad fuels and engines.
Standards for trucks and buses using diesel engines were also strengthened. The 1990
amendments required new urban buses to reduce emissions of diesel particulates 92% by 1996,
and all other heavy-duty diesel engines to achieve an 83% reduction by the same year. NOx
emissions must also be reduced, 33% by 1998. Authority to further strengthen these standards led
to promulgation in January 2001 of new emission standards requiring a further 90%-95%
reduction in emissions phased in over the 2007-2010 model years, and a reduction of 97% in the
allowable amount of sulfur in highway diesel fuel. These regulations were followed in May 2004
by similar requirements for nonroad diesel equipment, which will be phased in between 2007 and
2015.
Hazardous Air Pollutants3
Completely rewritten by the Clean Air Act Amendments of 1990, Section 112 of the Act
establishes programs for protecting public health and the environment from exposure to toxic air
pollutants. As revised by the 1990 amendments, the section contains four major provisions:
Maximum Achievable Control Technology (MACT) requirements; health-based standards;
standards for stationary “area sources” (small, but numerous sources, such as gas stations or dry
cleaners, that collectively emit significant quantities of hazardous pollutants); and requirements
for the prevention of catastrophic releases.
First, EPA is to establish technology-based emission standards, called MACT standards, for
sources of 187 pollutants listed in the legislation, and to specify categories of sources subject to
the emission standards.4 EPA is to revise the standards periodically (at least every eight years).
EPA can, on its own initiative or in response to a petition, add or delete substances or source
categories from the lists.
Section 112 establishes a presumption in favor of regulation for the designated chemicals; it
requires regulation of a designated pollutant unless EPA or a petitioner is able to show “that there
is adequate data on the health and environmental effects of the substance to determine that
emissions, ambient concentrations, bioaccumulation or deposition of the substance may not
reasonably be anticipated to cause any adverse effects to human health or adverse environmental
effects.”
EPA is required to set standards for sources of the listed pollutants that achieve “the maximum
degree of reduction in emissions” taking into account cost and other non-air-quality factors.
These MACT standards for new sources “shall not be less stringent than the most stringent
emissions level that is achieved in practice by the best controlled similar source.” The standards
for existing sources may be less stringent than those for new sources, but must be no less
stringent than the emission limitations achieved by either the best performing 12% of existing
sources (if there are more than 30 such sources in the category or subcategory) or the best

3 This section of the report was written by Linda-Jo Schierow, Specialist in Environmental Policy.
4 The 1990 amendments specified 189 pollutants, but P.L. 102-187, enacted on December 4, 1991, deleted hydrogen
sulfide from the list of toxic pollutants, leaving only 188. On December 19, 2005, EPA removed methyl ethyl ketone
(MEK) from the list of toxic air pollutants. The total number of listed air toxics is now 187.
Congressional Research Service
10

Clean Air Act: A Summary of the Act and Its Major Requirements

performing 5 similar sources (if there are fewer than 30). Existing sources are given three years
following promulgation of standards to achieve compliance, with a possible one-year extension;
additional extensions may be available for special circumstances or for certain categories of
sources. Existing sources that achieve voluntary early emissions reductions will receive a six-year
extension for compliance with MACT.
The second major provision of Section 112 directs EPA to set health-based standards to address
situations in which a significant residual risk of adverse health effects or a threat of adverse
environmental effects remains after installation of MACT. This provision requires that EPA, after
consultation with the Surgeon General of the United States, submit a report to Congress on the
public health significance of residual risks, and recommend legislation regarding such risks. If
Congress does not legislate in response to EPA’s recommendations, then EPA is required to issue
standards for categories of sources of hazardous air pollutants as necessary to protect the public
health with an ample margin of safety or to prevent an adverse environmental effect. A residual
risk standard is required for any source emitting a cancer-causing pollutant that poses an added
risk to the most exposed person of more than one-in-a-million. Residual risk standards are due
eight years after promulgation of MACT for the affected source category. Existing sources have
90 days to comply with a residual risk standard, with a possible two-year extension. In general,
residual risk standards do not apply to area sources.
The law directed EPA to contract with the National Academy of Sciences (NAS) for a study of
risk assessment methodology, and created a Risk Assessment and Management Commission to
investigate and report on policy implications and appropriate uses of risk assessment and risk
management. In 1994 NAS published its report, Science and Judgment in Risk Assessment. The
Commission study, Framework for Environmental Health Risk Management, was released in
1997.
Third, in addition to the technology-based and health-based programs for major sources of
hazardous air pollution, EPA is to establish standards for stationary “area sources” determined to
present a threat of adverse effects to human health or the environment. The provision requires
EPA to regulate the stationary area sources responsible for 90% of the emissions of the 30
hazardous air pollutants that present the greatest risk to public health in the largest number of
urban areas. In setting the standard, EPA can impose less stringent “generally available” control
technologies, rather than MACT.
Finally, Section 112 addresses prevention of sudden, catastrophic releases of air toxics by
establishing an independent Chemical Safety and Hazard Investigation Board. The Board is
responsible for investigating accidents involving releases of hazardous substances, conducting
studies, and preparing reports on the handling of toxic materials and measures to reduce the risk
of accidents.
EPA is also directed to issue prevention, detection, and correction requirements for catastrophic
releases of air toxics by major sources. Section 112(r) requires owners and operators to prepare
risk management plans including hazard assessments, measures to prevent releases, and a
response program.
Congressional Research Service
11

Clean Air Act: A Summary of the Act and Its Major Requirements

New Source Performance Standards5
Section 111 of the Act requires EPA to establish nationally uniform, technology-based standards
(called New Source Performance Standards, or NSPS) for categories of new industrial facilities.
These standards accomplish two goals: first, they establish a consistent baseline for pollution
control that competing firms must meet, and thereby remove any incentive for states or
communities to weaken air pollution standards in order to attract polluting industry; and second,
they preserve clean air to accommodate future growth, as well as for its own benefits.
NSPS establish maximum emission levels for new major stationary sources—powerplants, steel
mills, and smelters, for example—with the emission levels determined by the best “adequately
demonstrated” continuous control technology available, taking costs into account. EPA must
regularly revise and update NSPS applicable to designated sources as new technology becomes
available, since the goal is to prevent new pollution problems from developing and to force the
installation of new control technology.
The standards also apply to modifications of existing facilities, through a process called New
Source Review (NSR). The law’s ambiguity regarding what constitutes a modification (subject to
NSR) as opposed to routine maintenance of a facility has led to litigation, with EPA proposing in
recent years to modify its interpretation of the requirements of this section.
Solid Waste Incinerators
Prior to 1990, solid waste incinerators, which emit a wide range of pollutants, were subject to
varying degrees of state and federal regulation depending on their size, age, and the type of waste
burned. In a new Section 129, the 1990 amendments established more consistent federal
requirements specifying that emissions of 10 categories of pollutants be regulated at new and
existing incinerators burning municipal solid waste, medical waste, and commercial and
industrial waste. The amendments also established emissions monitoring and operator training
requirements.
Prevention of Significant Deterioration / Regional
Haze6

Sections 160-169 of the act establish requirements for the prevention of significant deterioration
of air quality (PSD). The PSD program reflects the principle that areas where air quality is better
than that required by NAAQS should be protected from significant new air pollution even if
NAAQS would not be violated.
The Act divides clean air areas into three classes, and specifies the increments of SO2 and
particulate pollution allowed in each. Class I areas include international and national parks,

5 This section of the report was written by Larry B. Parker, Specialist in Energy and Environmental Policy.
6 This section of the report was written by Larry B. Parker, Specialist in Energy and Environmental Policy and James
E. McCarthy, Specialist in Environmental Policy.
Congressional Research Service
12

Clean Air Act: A Summary of the Act and Its Major Requirements

wilderness and other pristine areas; allowable increments of new pollution are very small. Class II
areas include all attainment and not classifiable areas, not designated as Class I; allowable
increments of new pollution are modest. Class III represents selected areas that states may
designate for development; allowable increments of new pollution are large (but not exceeding
NAAQS). Through an elaborate hearing and review process, a state can have regions redesignated
from Class II to Class III (although none have yet been so redesignated).
While the 1977 amendments only stipulated PSD standards for two pollutants, SO2 and
particulates, EPA is supposed to establish standards for other criteria pollutants. Thus far, only
one of the other four (NO2) has been addressed: the agency promulgated standards for NO2 in
1988.
Newly constructed polluting sources in PSD areas must install best available control technology
(BACT) that may be more strict than that required by NSPS. The justifications of the policy are
that it protects air quality, provides an added margin of health protection, preserves clean air for
future development, and prevents firms from gaining a competitive edge by “shopping” for clean
air to pollute.
In Sections 169A and B, the Act also sets a national goal of preventing and remedying
impairment of visibility in national parks and wilderness areas, and requires EPA to promulgate
regulations to assure reasonable progress toward that goal. In the 1990 Amendments, Congress
strengthened these provisions, which had not been implemented.
The amendments required EPA to establish a Grand Canyon Visibility Transport Commission,
composed of Governors from each state in the affected region, an EPA designee, and a
representative of each of the national parks or wilderness areas in the region. Other visibility
transport commissions can be established upon EPA’s discretion or upon petition from at least two
states. Within 18 months of receiving a report from one of these commissions, EPA is required to
promulgate regulations to assure reasonable progress toward the visibility goal, including
requirements that states update their State Implementation Plans to contain emission limits,
schedules of compliance, and other measures necessary to make reasonable progress. Specifically
mentioned is a requirement that states impose Best Available Retrofit Technology on existing
sources of emissions impairing visibility.
The Grand Canyon Commission delivered a set of recommendations to EPA in June 1996, and the
agency subsequently promulgated a “regional haze” program applicable to all 50 states under this
authority.
Acid Deposition Control7
The Clean Air Act Amendments of 1990 added an acid deposition control program (Title IV) to
the Act. It set goals for the year 2000 of reducing annual SO2 emissions by 10 million tons from
1980 levels and reducing annual NOx emissions by 2 million tons, also from 1980 levels.
The SO2 reductions were imposed in two steps. Under Phase 1, owners/operators of 111 electric
generating facilities listed in the law that are larger than 100 megawatts had to meet tonnage

7 This section of the report was written by Larry B. Parker, Specialist in Energy and Environmental Policy.
Congressional Research Service
13

Clean Air Act: A Summary of the Act and Its Major Requirements

emission limitations by January 1, 1995. This would reduce SO2 emission by about 3.5 million
tons. Phase 2 included facilities larger than 75 megawatts, with a deadline of January 1, 2000.
Compliance has been 100%.
To introduce some flexibility in the distribution and timing of reductions, the Act creates a
comprehensive permit and emissions allowance system. An allowance is a limited authorization
to emit a ton of SO2. Issued by EPA, the allowances would be allocated to Phase 1 and Phase 2
units in accordance with baseline emissions estimates. Powerplants which commence operation
after November 15, 1990 would not receive any allowances. These new units would have to
obtain allowances (offsets) from holders of existing allowances. Allowances may be traded
nationally during either phase. The law also permitted industrial sources and powerplants to sell
allowances to utility systems under regulations developed by EPA. Allowances may be banked by
a utility for future use or sale.
The Act provided for two types of sales to improve the liquidity of the allowance system and to
ensure the availability of allowances for utilities and independent power producers who need
them. First, a special reserve fund consisting of 2.8% of Phase 1 and Phase 2 allowance
allocations has been set aside for sale. Allowances from this fund (25,000 annually from 1993-
1999 and 50,000 thereafter) are sold at a fixed price of $1,500 an allowance. Independent power
producers have guaranteed rights to these allowances under certain conditions. Second, an annual,
open auction sold allowances (150,000 from 1993-1995, and 250,000 from 1996-1999) with no
minimum price. Utilities with excess allowances may have them auctioned off at this auction, and
any person may buy allowances.
The Act essentially caps SO2 emissions at individual existing sources through a tonnage
limitation, and at future plants through the allowance system. First, emissions from most existing
sources are capped at a specified emission rate times an historic baseline level. Second, for plants
commencing operation after November 15, 1990, emissions must be completely offset with
additional reductions at existing facilities beginning after Phase 2 compliance. However, as noted
above, the law provides some allowances to future powerplants which meet certain criteria. The
utility SO2 emission cap was set at 8.9 million tons, with some exceptions.
The Act provides that if an affected unit does not have sufficient allowances to cover its
emissions, it is subject to an excess emission penalty of $2,000 per ton of SO2 and required to
reduce an additional ton of SO2 the next year for each ton of excess pollutant emitted.
The Act also requires EPA to inventory industrial emissions of SO2 and to report every five years,
beginning in 1995. If the inventory shows that industrial emissions may reach levels above 5.60
million tons per year, then EPA is to take action under the Act to ensure that the 5.60 million ton
cap is not exceeded.
The Act requires EPA to set specific NOx emission rate limitations—0.45 lb. per million Btu for
tangentially-fired boilers and 0.50 lb. per million Btu for wall-fired boilers—unless those rates
can not be achieved by low-NOx burner technology. Tangentially and wall-fired boilers affected
by Phase 1 SO2 controls must also meet NOx requirements. EPA was to set emission limitations
for other types of boilers by 1997 based on low-NOx burner costs, which EPA did. In addition,
EPA was to propose and promulgate a revised new source performance standard for NOx from
fossil fuel steam generating units, which EPA also did, in 1998.
Congressional Research Service
14

Clean Air Act: A Summary of the Act and Its Major Requirements

Permits8
The Clean Air Act Amendments of 1990 added a Title V to the Act which requires states to
administer a comprehensive permit program for the operation of sources emitting air pollutants.
These requirements are modeled after similar provisions in the Clean Water Act. Previously, the
Clean Air Act contained limited provision for permits, requiring only new or modified major
stationary sources to obtain construction permits (under Section 165 of the Act).
Sources subject to the permit requirements generally include major sources that emit or have the
potential to emit 100 tons per year of any regulated pollutant, plus stationary and area sources that
emit or have potential to emit lesser specified amounts of hazardous air pollutants. However, in
nonattainment areas, the permit requirements also include sources which emit as little as 50, 25,
or 10 tons per year of VOCs, depending on the severity of the region’s nonattainment status
(serious, severe, or extreme).
States were required to develop permit programs and to submit those programs for EPA approval
by November 15, 1993. EPA had one year to approve or disapprove a state’s submission in whole
or in part. After the effective date of a state plan, sources had 12 months to submit an actual
permit application.
States are to collect annual fees from sources sufficient to cover the “reasonable costs” of
administering the permit program, with revenues to be used to support the agency’s air pollution
control program. The fee must be at least $25 per ton of regulated pollutants (excluding carbon
monoxide). Permitting authorities have discretion not to collect fees on emissions in excess of
4,000 tons per year and may collect other fee amounts, if appropriate.
The permit states how much of which air pollutants a source is allowed to emit. As a part of the
permit process, a source must prepare a compliance plan and certify compliance. The term of
permits is limited to no more than five years; sources are required to renew permits at that time.
State permit authorities must notify contiguous states of permit applications that may affect them;
the application and any comments of contiguous states must be forwarded to EPA for review. EPA
can veto a permit; however, this authority is essentially limited to major permit changes. EPA
review need not include permits which simply codify elements of a state’s overall clean air plan,
and EPA has discretion to not review permits for small sources. Holding a permit to some extent
shields a source from enforcement actions: the Act provides that a source cannot be held in
violation if it is complying with explicit requirements addressed in a permit, or if the state finds
that certain provisions do not apply to that source.
Enforcement
Section 113 of the Act, which was also strengthened by the 1990 amendments, covers
enforcement. The section establishes federal authority to issue agency and court orders requiring
compliance and to impose penalties for violations of Act requirements. Section 114 authorizes
EPA to require sources to submit reports, monitor emissions, and certify compliance with the
Act’s requirements, and authorizes EPA personnel to conduct inspections.

8 This section of the report was written by Claudia Copeland, Specialist in Environmental Policy.
Congressional Research Service
15

Clean Air Act: A Summary of the Act and Its Major Requirements

Like most federal environmental statutes, the Clean Air Act is enforced primarily by states or
local governments; they issue most permits, monitor compliance, and conduct the majority of
inspections. The federal government functions as a backstop, with authority to review state
actions. The agency may act independently or may file its own enforcement action in cases where
it concludes that a state’s response was inadequate.
The Act also provides for citizen suits both against persons (including corporations or
government agencies) alleged to have violated emissions standards or permit requirements, and
against EPA in cases where the Administrator has failed to perform an action that is not
discretionary under the Act. Citizen groups have often used the latter provision to compel the
Administrator to promulgate regulations required by the statute.
The 1990 Amendments elevated penalties for some knowing violations from misdemeanors to
felonies; removed the ability of a source to avoid an enforcement order or civil penalty by ceasing
a violation within 60 days of notice; gave authority to EPA to assess administrative penalties; and
authorized $10,000 awards to persons supplying information leading to convictions under the Act.
Stratospheric Ozone Protection9
Title VI of the 1990 Clean Air Act Amendments represents the United States’ primary response on
the domestic front to the ozone depletion issue. It also implements the U.S. international
responsibilities under the Montreal Protocol on Substances that Deplete the Ozone Layer (and its
amendments). Indeed, Section 606(a)(3) provides that the Environmental Protection Agency shall
adjust phase-out schedules for ozone-depleting substances in accordance with any future changes
in Montreal Protocol schedules. As a result, the phase-out schedules contained in Title VI for
various ozone-depleting compounds have now been superseded by subsequent amendments to the
Montreal Protocol.
Since passage of Title VI, depleting substances such as CFCs, methyl chloroform, carbon
tetrachloride, and halons (referred to as Class 1 substances) have been phased out by industrial
countries, including the United States. New uses of hydrochlorofluorocarbons (HCFCs) (called
Class 2 substances under Title VI) are banned beginning January 1, 2015, unless the HCFCs are
recycled, used as a feedstock, or used as a refrigerant for appliances manufactured prior to
January 1, 2020. Production of HCFCs is to be frozen January 1, 2015 and phased out by January
1, 2030. Exemptions consistent with the Montreal Protocol are allowed.
The EPA is required to add any substance with an ozone depletion potential (ODP) of 0.2 or
greater to the list of Class 1 substances and set a phase-out schedule of no more than seven years.
For example, methyl bromide (ODP estimated by EPA at 0.7) was added to the list in December
1993, requiring its phaseout by January 1, 2001; this decision was altered by Congress in 1998 to
harmonize the U.S. methyl bromide phase-out schedule with the 2005 deadline set by the parties
to the Montreal Protocol in 1997. Also, EPA is required to add any substance that is known or
may be reasonably anticipated to harm the stratosphere to the list of Class 2 substances and set a
phase-out schedule of no more than ten years.

9 This section of the report was written by Larry B. Parker, Specialist in Energy and Environmental Policy.
Congressional Research Service
16

Clean Air Act: A Summary of the Act and Its Major Requirements

Title VI contains several implementing strategies to avoid releases of ozone-depleting chemicals
to the atmosphere, including (1) for Class 1 substances used as refrigerant—lowest achievable
level of use and emissions, maximum recycling, and safe disposal required by July 1, 1992; (2)
for servicing or disposing refrigeration equipment containing Class 1 and 2 substances—venting
banned as of July 1, 1992; (3) for motor vehicle air conditioners containing Class 1 or 2
substances—recycling required by January 1, 1992 (smaller shops by January 1, 1993); (4) sale of
small containers of class 1 and 2 substances—banned within two years of enactment; and (5)
nonessential products—banned within two years of enactment.
Selected References
U.S. Environmental Protection Agency. Office of Air Quality Planning and Standards. Air Trends.
Research Triangle Park, NC. Compiled annually, and available at http://www.epa.gov/airtrends/.
Martineau, Robert J., Jr. and Novello, David P. (eds.). The Clean Air Act Handbook. 2nd edition.
Chicago: American Bar Association, 2004. 728 p.
For recent issues, see CRS Report R41563, Clean Air Issues in the 112th Congress, by James E.
McCarthy.
Congressional Research Service
17

Clean Air Act: A Summary of the Act and Its Major Requirements

Table 3. Major U.S. Code Sections of the Clean Air Act
(codified generally as 42 U.S.C. 7401-7671)
Clean Air Act, as
42 U.S.C.
Section Title
amended
Subchapter I -
Programs and Activities

Part A -
Air Quality Emissions and Limitations

7401 Findings,
purpose
Sec.
101
7402
Cooperative activities
Sec. 102
7403
Research, investigation, training
Sec. 103
7404
Research relating to fuels and vehicles
Sec. 104
7405
Grants for air pollution planning and control programs
Sec. 105
7406
Interstate air quality agencies; program cost limitations
Sec. 106
7407
Air quality control regions
Sec. 107
7408
Air quality criteria and control techniques
Sec. 108
7409
National primary and secondary air quality standards
Sec. 109
7410
SIPs for national primary and secondary air quality standards
Sec. 110
7411
Standards of performance for new stationary sources
Sec. 111
7412
Hazardous air pollutants
Sec. 112
7413
Federal enforcement
Sec. 113
7414
Recordkeeping, inspections, monitoring, and entry
Sec. 114
7415
International air pollution
Sec. 115
7416
Retention of state authority
Sec. 116
7417 Advisory
committees
Sec.
117
7418
Control of pollution from federal facilities
Sec. 118
7419
Primary nonferrous smelter orders
Sec. 119
7420
Noncompliance penalty
Sec. 120
7421 Consultation
Sec.
121
7422
Listing of certain unregulated pollutants
Sec. 122
7423
Stack heights
Sec. 123
7424
Assurance of adequacy of state plans
Sec. 124
7425
Measures to prevent economic disruption/unemployment
Sec. 125
7426
Interstate pollution abatement
Sec. 126
7427
Public notification
Sec. 127
7428 State
boards
Sec.
128
7429
Solid waste combustion
Sec. 129
7430 Emission
factors
Sec.
130
7431
Land use authority
Sec. 131

Congressional Research Service
18

Clean Air Act: A Summary of the Act and Its Major Requirements

Clean Air Act, as
42 U.S.C.
Section Title
amended
Part B - Ozone Protection (repealed—new provisions related to stratospheric ozone protection are found at 42
U.S.C. 7671 et seq., below)

Part C -
Prevention of Significant Deterioration of Air Quality
Subpart I -
Clean Air

7470
Congressional declaration of purpose
Sec. 160
7471
Plan requirements
Sec. 161
7472 Initial
classifications
Sec.
162
7473 Increments
and
ceilings Sec.
163
7474
Area redesignation
Sec. 164
7475
Preconstruction requirements
Sec. 165
7476
Other pollutants
Sec. 166
7477 Enforcement
Sec.
167
7478
Period before plan approval
Sec. 168
7479
Definitions
Sec. 169

Subpart II -
Visibility Protection

7491 Visibility protection for federal class I areas
Sec. 169A
7492 Visibility Sec.
169B

Part D -
Plan Requirements for Nonattainment Areas

Subpart 1 -
Nonattainment Areas in General

7501 Definitions
Sec.
171
7502
Nonattainment plan provisions in general
Sec. 172
7503
Permit requirements
Sec. 173
7504
Planning procedures
Sec. 174
7505
Environmental Protection Agency grants
Sec. 175
7505a
Maintenance plans
Sec. 175A
7506
Limitations on certain federal assistance
Sec. 176
7506a
Interstate transport commissions
Sec. 176A
7507
New motor vehicle emission standards in nonattainment areas
Sec. 177
7508
Guidance documents
Sec. 178
7509
Sanctions and consequences of failure to attain
Sec. 179
7509a
International border areas
Sec. 179B

Subpart 2 -
Additional Provisions for Ozone Nonattainment Areas
7511
Classifications and attainment dates
Sec. 181
Congressional Research Service
19

Clean Air Act: A Summary of the Act and Its Major Requirements

Clean Air Act, as
42 U.S.C.
Section Title
amended
7511a
Plan submissions and requirements
Sec. 182
7511b
Federal ozone measures
Sec. 183
7511c
Control of interstate ozone air pol ution
Sec. 184
7511d
Enforcement for Severe and Extreme ozone nonattainment areas for
Sec. 185
failure to attain
7511e
Transitional areas
Sec. 185A
7511f NOx and VOC study
Sec. 185B

Subpart 3 -
Additional Provisions for Carbon Monoxide Nonattainment Areas
7512
Classification and attainment dates
Sec. 186
7512a
Plan submissions and requirements
Sec. 187

Subpart 4 -
Additional Provisions for Particulate Matter Nonattainment Areas
7513
Classifications and attainment dates
Sec. 188
7513a
Plan provisions and schedules for plan submissions
Sec. 189
7513b
Issuance of RACM and BACM guidance
Sec. 190

Subpart 5 -
Additional Provisions for Areas Designated Nonattainment for Sulfur Oxides, Nitrogen Dioxide,
or Lead
7514
Plan submission deadlines
Sec. 191
7514a
Attainment dates
Sec. 192

Subpart 6 -
Savings Provisions

7515
General savings clause
Sec. 193

Subchapter II -
Emission Standards for Moving Sources

Part A -
Motor Vehicle Emission and Fuel Standards

7521
Emission standards for new motor vehicles or engines
Sec. 202
7522
Prohibited acts
Sec. 203
7523
Actions to restrain violations
Sec. 204
7524
Civil penalties
Sec. 205
7525
Motor vehicle and engines testing and certification
Sec. 206
7541
Compliance by vehicles and engines in actual use
Sec. 207
7542
Information col ection
Sec. 208
7543 State
standards
Sec.
209
7544
State grants
Sec. 210
7545
Regulation of fuels
Sec. 211
Congressional Research Service
20

Clean Air Act: A Summary of the Act and Its Major Requirements

Clean Air Act, as
42 U.S.C.
Section Title
amended
7547
Nonroad engines and vehicles
Sec. 213
7548
Study of particulate emissions from motor vehicles
Sec. 214
7549
High altitude performance adjustments
Sec. 215
7550 Definitions
Sec.
216
7551
Study and report on fuel consumption of CAAA of 1977
Sec. 203
7552
Motor vehicle compliance program fees
Sec. 217
7553
Prohibition on production of engines requiring leaded gasoline
Sec. 218
7554
Urban bus standards
Sec. 219

Part B -
Aircraft Emissions Standards

7571
Establishment of standards
Sec. 231
7572
Enforcement of standards
Sec. 232
7573
State standards and controls
Sec. 233
7574 Definitions
Sec.
234

Part C -
Clean Fuel Vehicles

7581 Definitions
Sec.
241
7582
Requirements applicable to clean-fuel vehicles
Sec. 242
7583
Standards for light-duty clean-fuel vehicles
Sec. 243
7584
Administration and enforcement as per California standards
Sec. 244
7585
Standards for heavy-duty clean-fuel vehicles
Sec. 245
7586
Central y fueled fleets
Sec. 246
7587 Vehicle
conversions
Sec.
247
7588
Federal agency fleets
Sec. 248
7589
California pilot test program
Sec. 249
7590
General provisions
Sec. 250

Subchapter III -
General Provisions

7601 Administration
Sec.
301
7602 Definitions
Sec.
302
7603
Emergency powers
Sec. 303
7604
Citizen suits
Sec. 304
7605
Representation in litigation
Sec. 305
7606
Federal procurement
Sec. 306
7607
Administrative proceedings and judicial review
Sec. 307
7608
Mandatory licensing
Sec. 308
Congressional Research Service
21

Clean Air Act: A Summary of the Act and Its Major Requirements

Clean Air Act, as
42 U.S.C.
Section Title
amended
7609 Policy
review
Sec.
309
7610
Other authority
Sec. 310
7611
Records and audits
Sec. 311
7612
Economic impact analyses
Sec. 312
7614
Labor standards
Sec. 314
7615 Separability Sec.
315
7616
Sewage treatment plants
Sec. 316
7617
Economic impact assessment
Sec. 317
7619
Air quality monitoring
Sec. 319
7620
Standardized air quality modeling
Sec. 320
7621
Employment effects
Sec. 321
7622
Employee protection
Sec. 322
7624
Cost of vapor recovery equipment
Sec. 323
7625
Vapor recovery for smal business marketers of petroleum products
Sec. 324
7625-1
Exemptions for certain territories
Sec. 325
7625a Statutory
construction
Sec.
326
7626
Authorization of appropriations
Sec. 327
7627
Air pollution from Outer Continental Shelf activities
Sec. 328

Subchapter IV-A
Acid Deposition Control

7651
Findings and purposes
Sec. 401
7651a Definitions
Sec.
402
7651b
Sulfur dioxide al owance program for existing and new units
Sec. 403
7651c
Phase I sulfur dioxide requirements
Sec. 404
7651d
Phase II sulfur dioxide requirements
Sec. 405
7651e
Al owances for states with emissions rates at or below 0.80
Sec. 406
lbs./mmBtu
7651f
Nitrogen oxides emission reduction program
Sec. 407
7651g
Permits and compliance plans
Sec. 408
7651h
Repowered sources
Sec. 409
7651i
Election for additional sources
Sec. 410
7651j
Excess emissions penalty
Sec. 411
7651k
Monitoring, reporting, and recordkeeping requirements
Sec. 412
7651l
General compliance with other provisions
Sec. 413
7651m Enforcement
Sec.
414
7651n
Clean coal technology regulatory incentives
Sec. 415
7651o
Contingency guarantee, auctions, reserve
Sec. 416
Congressional Research Service
22

Clean Air Act: A Summary of the Act and Its Major Requirements

Clean Air Act, as
42 U.S.C.
Section Title
amended

Subchapter V -
Permits

7661 Definitions
Sec.
501
7661a
Permit programs
Sec. 502
7661b
Permit applications
Sec. 503
7661c
Permit requirements and conditions
Sec. 504
7661d
Notification to administrator and contiguous states
Sec. 505
7661e
Other authorities
Sec. 506
7661f
Smal business stationary source technical and environmental
Sec. 507
compliance assistance program

Subchapter VI -
Stratospheric Ozone Protection

7671 Definitions
Sec.
601
7671a
Listing of class I and class II substances
Sec. 602
7671b
Monitoring and reporting requirements
Sec. 603
7671c
Phase-out of production and consumption of class I substances
Sec. 604
7671d
Phase-out of production and consumption of class II substances
Sec. 605
7671e Accelerated
schedule
Sec.
606
7671f
Exchange authority
Sec. 607
7671g
National recycling and emission reduction program
Sec. 608
7671h
Servicing of motor vehicle air conditioners
Sec. 609
7671i
Nonessential products containing chlorofluorocarbons
Sec. 610
7671j Labeling
Sec.
611
7671k
Safe alternatives policy
Sec. 612
7671l
Federal procurement
Sec. 613
7671m
Relationship to other laws
Sec. 614
7671n
Authority of Administrator
Sec. 615
7671o
Transfers among parties to Montreal Protocol
Sec. 616
7671p International
cooperation
Sec.
617
7671q Miscel aneous
provisions
Sec.
618

[29 U.S.C. 655]
Chemical Process Safety Management
Sec. 304 of CAA of
1990
[29 U.S.C.
Clean Air Employment Transition Assistance
Sec.1101 of CAA of
1662e]
1990
Note: This table shows only the major U.S. Code sections. For more detail and to determine when a section
was added, the reader should consult the official printed version of the U.S. Code.

Congressional Research Service
23

Clean Air Act: A Summary of the Act and Its Major Requirements

Author Contact Information

James E. McCarthy
Larry Parker
Specialist in Environmental Policy
Specialist in Energy and Environmental Policy
jmccarthy@crs.loc.gov, 7-7225
lparker@crs.loc.gov, 7-7238
Claudia Copeland
Linda-Jo Schierow
Specialist in Resources and Environmental Policy
Specialist in Environmental Policy
ccopeland@crs.loc.gov, 7-7227
lschierow@crs.loc.gov, 7-7279


Congressional Research Service
24