Clean Air Act (United States)
||This article may require cleanup to meet Wikipedia's quality standards. The specific problem is: extensive rewrite needed for organization, use of bureaucratese, unidentified acronyms. Legislative history and section by section blow by blow should be separated out from a discussion of the effect and importance of the Act. See comments on talk page for specific examples. (December 2012)|
|Effective||Dec. 17, 1963|
|Public Law||P.L. 88-206|
|Stat.||77 Stat. 392|
|Title(s) amended||42 (Public Health)|
|U.S.C. sections created||7401|
|United States Supreme Court cases|
|Union Elec. Co. v. EPA, 427 U.S. 246 (1976)
Chevron USA v. Natural Resources Defense Council, 467 U.S. 837 (1984).
The Clean Air Act is a United States federal law designed to control air pollution on a national level. It requires the Environmental Protection Agency (EPA) to develop and enforce regulations to protect the public from airborne contaminants known to be hazardous to human health. The 1963 version of the legislation established a research program, expanded in 1967. Major amendments to the law, requiring regulatory controls for air pollution, passed in 1970, 1977 and 1990.
The 1970 amendments greatly expanded the federal mandate, requiring comprehensive federal and state regulations for both stationary (industrial) pollution sources and mobile sources. It also significantly expanded federal enforcement.
The 1990 amendments addressed acid rain, ozone depletion and toxic air pollution, established a national permits program for stationary sources, and increased enforcement authority. The amendments also established new auto gasoline reformulation requirements, set Reid vapor pressure (RVP) standards to control evaporative emissions from gasoline, and mandated new gasoline formulations sold from May to September in many states.
The Clean Air Act was the first major environmental law in the United States to include a provision for citizen suits. Numerous state and local governments have enacted similar legislation, either implementing federal programs or filling in locally important gaps in federal programs.
Components of Air Pollution Prevention and Control 
Title I - Programs and Activities 
Part A - Air Quality and Emissions Limitations 
This section of the act declares that protecting and enhancing the nation's air quality promotes public health. It encourages regional air pollution prevention and control programs and provides technical and financial assistance to state and local governments air pollution prevention. Additional subchapters cover of cooperation, research, investigation, training and other activities. Grants for air pollution planning and control programs, and interstate air quality agencies and program cost limitations are also included in this section of the act.
The act mandates air quality control regions, designated as attainment vs non-attainment. Nonattainment areas do not meet national standards for primary or secondary ambient air quality. Attainment areas meet these standards, while unclassfiable areas cannot be classified on the basis of the information that is available.
Air quality criteria, national primary and secondary ambient air quality standards, state implementation plans, and performance standards for new stationary sources are also covered in Part A. The list of hazardous air pollutants established by the act includes acetaldehyde, benzene, chloroform, phenols, and selenium compounds. The list also includes mineral fiber emissions from manufacturing or processing glass, rock or slag fibers as well as radioactive atoms. The list periodically can be modified. The act lists unregulated radioactive pollutants such as cadmium, arsenic, and polycyclic organic matter and mandates listing them if they will cause or contribute to air pollution that endangers public health, under section 7408 or 7412.
The remaining subchapters cover smokestack heights, state plan adequacy, and estimating emissions of carbon monoxide, volatile organic compounds, and oxides of nitrogen from area and mobile sources. Measures to prevent unemployment or other economic disruption include using local coal or coal derivatives to comply with implementation requirements. The final subchapter in this act focuses on land use authority.
Part B - Ozone Protection 
This change in the law reflected significant changes in scientific understanding of ozone formation and depletion. Ozone absorbs UVC light and shorter wave UVB, and lets through UVA, which is largely harmless to people. Ozone exists naturally in the stratosphere, not the troposphere. It is laterally distributed because it is destroyed by strong sunlight, so there is more ozone at the poles. Ozone is created when O2 comes in contact with photons from solar radiation. Therefore a decrease in the intensity of solar radiation also results in a decrease in the formation of ozone in the stratosphere. This exchange is known as the Chapman mechanism:
- O2 + UV photon → 2 O (note that atmospheric oxygen as O is highly unstable)
- O + O2 + M → O3 (O3 is Ozone) + M
- M represents a third molecule, needed to carry off the excess energy of the collision of O + O2.
Atmospheric freon and chlorofluorocarbons (CFCs) contribute to ozone depletion (Chlorine is a catalytic agent in ozone destruction). Following discovery of the ozone hole in 1985, the 1987 Montreal Protocol successfully implemented a plan to replace CFCs and was viewed by some environmentalists as an example of what is possible for the future of environmental issues, if the political will is present.
Part C - Prevention of Significant Deterioration of Air Quality 
The Clean Air Act requires permits to build or add to major stationary sources of air pollution. This permitting process, known as New Source Review (NSR), applies to sources in areas that meet air quality standards as well as areas that do not or are unclassifiable. Permits in attainment or unclassifiable areas are referred to as Prevention of Significant Deterioration (PSD) permits, while permits for sources located in nonattainment areas are referred to as nonattainment area (NAA) permits.
The fundamental goals of the PSD program are to:
- prevent new nonattainment areas by ensuring economic growth in harmony with existing clean air;
- protect public health and welfare from any adverse effects;
- preserve and enhance the air quality in national parks and other areas of special natural recreational, scenic, or historic value.:3
Part D - Plan Requirements for Nonattainment Areas 
Under the Clean Air Act states are required to submit a plan for non-attainment areas to reach attainment status as soon as possible but in no more than five years, based on the severity of the air pollution and the difficulty posed by obtaining cleaner air.
The plan must include:
- an inventory of all pollutants
- control measures, means, and techniques to reach standard qualifications
- contingency measures
The plan must be approved or revised if required for approval, and specify whether local governments or the state will implement and enforce the various changes. Achieving attainment status makes a request for reevaluation possible. It must include a plan for maintenance of air quality.
Title II - Emission Standards for Moving Sources 
Part A - Motor Vehicle Emission and Fuel Standards (CAA § 201-219; USC § 7521-7554) 
Subchapters of Title II cover state standards and grants, prohibited acts and actions to restrain violations, as well as a study of emissions from nonroad vehicles (other than locomotives) to determine whether they cause or contribute to air pollution. Motorcycles are treated in the same way as automobiles under the emission standards for new motor vehicles or motor vehicle engines. The last few subchapters deal with high altitude performance adjustments, motor vehicle compliance program fees, prohibition on production of engines requiring leaded gasoline, and urban bus standards.
This part of the bill was extremely controversial the time it was passed. The automobile industry argued that it could not meet the new standards. Senators expressed concern about impact on the economy. Specific new emissions standards for moving sources passed years later.
Economists Daniel Khazzoom and Leonard Brookes noted in the 1980s that while the OPEC oil crises of 1973 and 1979 increased demand for greater fuel efficiency in automobiles, consumer behavior seemed to bear out the Jevons paradox, with increased automobile use balancing out much of the improvement in fuel efficiency since. Because cars are more efficient, the argument goes, driving is less costly, so people tend to drive more, and the tendency to increased driving outweighs the energy savings from improved fuel efficiency.
Part B - Aircraft Emission Standards 
Many volatile organic compounds (VOCs) are emitted over airports and affect the air quality in the region. VOCs include benzene, formaldehyde, and butadienes which are known to cause health problems such as birth defects, cancer, and skin irritation. Hundreds of tons of emissions from aircraft, ground support equipment, heating systems, and shuttles and passenger vehicles are released into the air, causing smog. Therefore, major cities such as Seattle, Denver, and San Francisco require a Climate Action Plan as well as a greenhouse gas inventory. Additionally, federal programs such as VALE[who?] are working to offset costs for programs that reduce emissions.
Title II sets emission standards for airlines and aircraft engines and adopts standards set by the International Civil Aviation Organization (ICAO). However aircraft carbon dioxide emission standards have not been established by either ICAO nor the EPA. It is the responsibility of the Secretary of Transportation, after consultation with the Administrator, to prescribe regulations that comply with section 7571[clarification needed] and ensure the necessary inspections take place.
Part C - Clean Fuel Vehicles 
Trucks and automobiles play a large role in deleterious air quality. Harmful chemicals such as nitrogen oxide, hydrocarbons, carbon monoxide, and sulfur dioxide are released from motor vehicles. Some of these also react with sunlight to produce photochemicals. These harmful substances change the climate, alter ocean pH and include toxins that may cause cancer, birth defects, or respiratory illness. Motor vehicles increased in the 1990s since approximately 58 percent of households owned two or more vehicles. The Clean Fuel Vehicle programs focused on alternative fuel use and petroleum fuels that met low emission vehicle (LEV) levels. Compressed natural gas, ethanol, methanol, liquefied petroleum gas, and electricity are examples of cleaner alternative fuel. Programs such as the California Clean Fuels Program and pilot program are increasing demand that for new fuels to be developed to reduce harmful emissions.
The California pilot program incorporated under this section focuses on pollution control in ozone nonattainment areas. The provisions apply to light-duty trucks and light-duty vehicles in California. The also state requires that clean alternative fuels for sale at numerous locations with sufficient geographic distribution for convenience. Production of clean-fuel vehicles isn't mandated except as part of the California pilot program.
Title III - General Provisions 
Under the law prior to 1990, EPA was required to construct a list of HAPs[who?] as well as health-based standards for each one. There were 188 air pollutants listed and the source[disambiguation needed] from which they came. The EPA was given ten years to generate technology-based emission standards. Title III is considered a second phase, allowing the EPA to assess lingering risks after the enactment of the first phase of emission standards. Title III is also to enact new standards with regard to the protection of public health.
A citizen may file a lawsuit to obtain compliance with an emission standard issued by the EPA or by a state, unless there is an ongoing enforcement action being pursued by EPA or the appropriate state agency.
Title IV - Noise Pollution 
This title pre-dates the Clean Air Act. With the passage of the Clean Air Act, it became codified as Title IV. However, another Title IV was enacted in the 1970 amendments. The second Title IV was then appended to this Title IV as Title IV-A (see below).
This title established the EPA Office of Noise Abatement and Control to reduce noise pollution in urban areas, to minimize noise-related impacts on psychological and physiological effects on humans, effects on wildlife and property (including values), and other noise-related issues. The agency was also assigned to run experiments to study the effects of noise.
Title IV-A - Acid Deposition Control 
This title was added as part of the 1990 amendments. It addresses the issue of acid rain, which is caused by nitrogen oxides (NOX) and sulfur dioxide (SO2) emissions from electric power plants powered by fossil fuels, and other industrial sources. The 1990 amendments gave industries more pollution control options including switching to low-sulfur coal and/or adding devices that controlled the harmful emissions. In some cases plants had to be closed down to prevent the dangerous chemicals from entering the atmosphere.
Title IV-A mandated a two-step process to reduce SO2 emissions. The first stage required more than 100 electric generating facilities larger than 100 megawatts to meet a 3.5 million ton SO2 emission reduction by January 1995. The second stage gave facilities larger than 75 megawatts a January 2000 deadline.
Title V - Permits 
The 1990 amendments authorized a national operating permit program, covering thousands of large industrial and commercial sources. It required large businesses to address pollutants released into the air, measure their quantity, and have a plan to control and minimize them as well as to periodically report. This consolidated requirements for a facility into a single document.
In non-attainment areas, permits were required for sources that emit as little as 50, 25, or 10 tons per year of VOCs depending on the severity of the region’s non-attainment status.
Most permits are issued by state and local agencies. If the state does not adequately monitor requirements, the EPA may take control. The public may request to view the permits by contacting the EPA. The permit is limited to no more than five years and requires a renewal.
Title VI - Stratospheric Ozone Protection 
Starting in 1990, Title VI mandated regulations regarding the use and production of chemicals that harm the Earth’s stratospheric ozone layer. This ozone layer protects against harmful ultraviolet B sunlight linked to several medical conditions including cataracts and skin cancer.
The ozone-destroying chemicals were been classified into two groups, Class I and Class II. Class I consists of substances, including chlorofluorocarbons, that have an ozone depletion potential (ODP) (HL) of 0.2 or higher. Class II lists substances, including hydrochlorofluorocarbons, that are known to or may be detrimental to the stratosphere. Both groups have a timeline for phase-out:
- For Class I substances, no more than seven years after being added to the list and
- For Class II substances no more than ten years.
Title VI establishes methods for preventing harmful chemicals from entering the stratosphere in the first place, including recycling or proper disposal of chemicals and finding substitutes that cause less or no damage.
Congress passed the first Clean Air Act in 1963, creating a research and regulatory program in the U.S. Public Health Service. The Act authorized development of emission standards for stationary sources, but not mobile sources.:211 The 1967 Air Quality Act mandated enforcement of interstate air pollution standards and authorized ambient monitoring studies and stationary source inspections.
In the Clean Air Act Extension of 1970, Congress greatly expanded the federal mandate by requiring comprehensive federal and state regulations for both industrial and mobile sources. The law established four new regulatory programs:
- National Ambient Air Quality Standards (NAAQS). EPA was required to promulgate national standards for six criteria pollutants: carbon monoxide, nitrogen dioxide, sulfur dioxide, particulate matter, hydrocarbons and photochemical oxidants. (Some of the criteria pollutants were revised in subsequent legislation.):213
- State Implementation Plans (SIPs)
- New Source Performance Standards (NSPS); and
- National Emissions Standards for Hazardous Air Pollutants (NESHAPs).
The 1970 law is sometimes called the "Muskie Act" because of the central role Maine Senator Edmund Muskie played in drafting the bill. The EPA was also created under the National Environmental Policy Act about the same time as these additions were passed, which was important to help implement the programs listed above.
The Clean Air Act Amendments of 1977 required Prevention of Significant Deterioration (PSD) of air quality for areas attaining the NAAQS, and added requirements for non-attainment areas.
The 1990 Clean Air Act added regulatory programs for control of acid deposition (acid rain) and stationary source operating permits. The amendments moved considerably beyond the original criteria pollutants, expanding the NESHAP program with a list of 189 hazardous air pollutants to be controlled within hundreds of source categories, according to a specific schedule. The NAAQS program was also expanded. Other new provisions covered stratospheric ozone protection, increased enforcement authority, and expanded research programs.
History of the Clean Air Act 
The legal authority for federal programs regarding air pollution control is based on the 1990 Clean Air Act Amendments (1990 CAAA). These are the latest in a series of amendments made to the Clean Air Act (CAA), often referred to as "the Act." This legislation modified and extended federal legal authority provided by the earlier Clean Air Acts of 1963 and 1970.
The Air Pollution Control Act of 1955 was the first federal legislation involving air pollution. This Act provided funds for federal research in air pollution. The Clean Air Act of 1963 was the first federal legislation regarding air pollution control. It established a federal program within the U.S. Public Health Service and authorized research into techniques for monitoring and controlling air pollution. In 1967, the Air Quality Act was enacted in order to expand federal government activities. In accordance with this law, enforcement proceedings were initiated in areas subject to interstate air pollution transport. As part of these proceedings, the federal government for the first time conducted extensive ambient monitoring studies and stationary source inspections.
The Air Quality Act of 1967 also authorized expanded studies of air pollutant emission inventories, ambient monitoring techniques, and control techniques.
Clean Air Act of 1970 
The Clean Air Act of 1970 (1970 CAA) authorized the development of comprehensive federal and state regulations to limit emissions from both stationary (industrial) sources and mobile sources. Four major regulatory programs affecting stationary sources were initiated:
- the National Ambient Air Quality Standards [NAAQS (pronounced "knacks")],
- State Implementation Plans (SIPs),
- New Source Performance Standards (NSPS),
- and National Emission Standards for Hazardous Air Pollutants (NESHAPs).
Enforcement authority was substantially expanded. This very important legislation was adopted at approximately the same time as the National Environmental Policy Act that established the U.S. Environmental Protection Agency (EPA); the EPA was created on May 2, 1971 in order to implement the various requirements included in the Clean Air Act of 1970.
Clean Air Act Amendments of 1977 
Major amendments were added to the Clean Air Act in 1977 (1977 CAAA). The 1977 Amendments primarily concerned provisions for the Prevention of Significant Deterioration (PSD) of air quality in areas attaining the NAAQS. The 1977 CAAA also contained requirements pertaining to sources in non-attainment areas for NAAQS. A non-attainment area is a geographic area that does not meet one or more of the federal air quality standards. Both of these 1977 CAAA established major permit review requirements to ensure attainment and maintenance of the NAAQS.
Clean Air Act Amendments of 1990 
Another set of major amendments to the Clean Air Act occurred in 1990 (1990 CAAA). The 1990 CAAA substantially increased the authority and responsibility of the federal government. New regulatory programs were authorized for control of acid deposition (acid rain) and for the issuance of stationary source operating permits. The NESHAPs were incorporated into a greatly expanded program for controlling toxic air pollutants. The provisions for attainment and maintenance of NAAQS were substantially modified and expanded. Other revisions included provisions regarding stratospheric ozone protection, increased enforcement authority, and expanded research programs.
Some of the principal milestones in the evolution of the Clean Air Act
The Air Pollution Control Act of 1955
- First federal air pollution legislation
- Funded research on scope and sources of air pollution
Clean Air Act' of 1963
- Authorized a national program to address air pollution
- Authorized research into techniques to minimize air pollution
Air Quality Act of 1967
- Authorized enforcement procedures involving interstate transport of pollutants
- Expanded research activities
Clean Air Act of 1970
- Established National Ambient Air Quality Standards
- Established requirements for State Implementation Plans to achieve them
- Establishment of New Source Performance Standards for new and modified stationary sources
- Establishment of National Emission Standards for Hazardous Air Pollutants
- Increased enforcement authority
- Authorized control of motor vehicle emissions
1977 Amendments to the Clean Air Act of 1970
- Authorized provisions related to prevention of significant deterioration
- Authorized provisions relating to non-attainment areas
1990 Amendments to the Clean Air Act of 1970
- Authorized programs for acid deposition control
- Authorized controls for 189 toxic pollutants, including those previously regulated by the national emission standards for hazardous air pollutants
- Established permit program requirements
- Expanded and modified provisions concerning National Ambient Air Quality Standards
- Expanded and modified enforcement authority
|This section requires expansion with: additional regulations. (June 2011)|
Since the initial establishment of six mandated criteria pollutants (ozone, particulate matter, carbon monoxide, nitrogen oxides, sulfur dioxide, and lead), advancements in testing and monitoring have led to the discovery of many other significant air pollutants.
However, with the act in place and its many improvements, the U.S. has seen many pollutant levels and associated cases of health complications drop. The 1990 Clean Air Act Amendments prevent:
|Adult Mortality - particles||160,000||230,000|
|Infant Mortality - particles||230||280|
|Mortality - ozone||4,300||71,000|
|Heart Disease - Acute Myocardial Infarction||130,000||200,000|
|Emergency Room Visits||86,000||120,000|
|School Loss Days||3,200,000||5,400,000|
|Lost Work Days||13,000,000||17,000,000|
This chart shows the health benefits of the Clean Air Act programs that reduce levels of fine particles and ozone.
In 1997 EPA tightened the NAAQS regarding permissible levels of the ground-level ozone that make up smog and the fine airborne particulate matter that makes up soot. The decision came after months of public review of the proposed new standards, as well as long and fierce internal discussion within the Clinton administration, leading to the most divisive environmental debate of that decade. The new regulations were challenged in the courts by industry groups as a violation of the U.S. Constitution's nondelegation principle and eventually landed in the U.S. Supreme Court, whose 2001 unanimous ruling in Whitman v. American Trucking Associations, Inc. largely upheld EPA's actions.
Roles of the federal government and states 
Although the 1990 Clean Air Act is a federal law covering the entire country, the states do much of the work to carry out the Act. The EPA has allowed the individual states to elect responsibility for compliance with and regulation of the CAA within their own borders in exchange for funding. For example, a state air pollution agency holds a hearing on a permit application by a power or chemical plant or fines a company for violating air pollution limits. However, election is not mandatory and in some cases states have chosen to not accept responsibility for enforcement of the act and force the EPA to assume those duties.
In order to take over compliance with the CAA the states must write and submit a state implementation plan (SIP) to the EPA for approval. A state implementation plan is a collection of the regulations a state will use to clean up polluted areas. The states are obligated to notify the public of these plans, though hearings that offer opportunities to comment, in the development of each state implementation plan. The SIP becomes the state's legal guide for local enforcement of the CAA. For example, Rhode Island law requires compliance with the Federal CAA through the SIP. The SIP delegates permitting and enforcement responsibility to the state Department of Environmental Management (RI-DEM).
The federal law recognizes that states should lead in carrying out the Clean Air Act, because pollution control problems often require special understanding of local industries, geography, housing patterns, etc. However, states are not allowed to have weaker pollution controls than the national minimum criteria set by EPA. EPA must approve each SIP, and if a SIP isn't acceptable, EPA can take over CAA enforcement in that state.
Metropolitan Planning Organizations must approve all federally funded transportation projects in a given urban area. If the MPO's plans do not, Federal Highway Administration and the Federal Transit Administration have the authority to withhold funds if the plans do not conform with federal requirements, including air quality standards.  In 2010, the EPA directly fined the San Joaquin Valley Air Pollution Control District $29 million for failure to meet ozone standards, resulting in fees for county drivers and businesses. This was the results of a federal appeals court case that required the EPA to continue enforce older, stronger standards, and spurred debate in Congress over amending the Act.
State Programs 
Many states, or concerned citizens of the state, have established their own programs to help promote pollution clean-up strategies.
- California - California's Clean Air Project - designed to create a smoke-free gaming atmosphere in tribal casinos
- Georgia - The Clean Air Campaign
- Texas - Drive Clean Across Texas
- New York - Clean Air NY
- Illinois - Illinois Citizens for Clean Air and Water - coalition of farmers and other citizens to reduce harmful effects of large-scale livestock production methods
- Virginia - Virginia Clean Cities, Inc.
Interstate air pollution 
Air pollution often travels from its source in one state to another state. In many metropolitan areas, people live in one state and work or shop in another; air pollution from cars and trucks may spread throughout the interstate area. The 1990 Clean Air Act provides for interstate commissions on air pollution control, which are to develop regional strategies for cleaning up air pollution. The 1990 amendments include other provisions to reduce interstate air pollution.
Leak detection and repair 
The Act requires industrial facilities to implement a Leak Detection and Repair (LDAR) program to monitor and audit a facility's fugitive emissions of volatile organic compounds (VOC). The program is intended to identify and repair components such as valves, pumps, compressors, flanges, connectors and other components that may be leaking. These components are the main source of the fugitive VOC emissions.
Testing is done manually using a portable vapor analyzer that read in parts per million (ppm). Monitoring frequency, and the leak threshold, is determined by various factors such as the type of component being tested and the chemical running through the line. Moving components such as pumps and agitators are monitored more frequently than non-moving components such as flanges and screwed connectors. The regulations require that when a leak is detected the component be repaired within a set amount of days. Most facilities get 5 days for an initial repair attempt with no more than 15 days for a complete repair. Allowances for delaying the repairs beyond the allowed time are made for some components where repairing the component requires shutting process equipment down.
Application to greenhouse gas emissions 
EPA began regulating greenhouse gases (GHGs) from mobile and stationary sources of air pollution under the Clean Air Act for the first time on January 2, 2011. Standards for mobile sources have been established pursuant to Section 202 of the CAA, and GHGs from stationary sources are controlled under the authority of Part C of Title I of the Act. See Regulation of Greenhouse Gases Under the Clean Air Act.
Below is a table for the sources of greenhouse gases, taken from data in 2008. Of all greenhouse gases, only about 54 percent of the sources are manageable under the CAA, marked with an asterisk (*). All others are regulated independently, if at all.
|Large Non-Agricultural Methane Sources*||5%|
|Light-, Medium-, and Heavy-Duty Vehicles||22%|
|Commercial and Residential Heating||7%|
See also 
- The Center for Clean Air Policy (in the US)
- Environmental policy of the United States
- Emission standards
- Emissions trading
- Startups, shutdowns, and malfunctions
- Commission on Risk Assessment and Risk Management
- Alan Carlin, controversy over the EPA carbon dioxide endangerment finding
- "Clean Air Act: Title I - Air Pollution Prevention and Control". U.S. Environmental Protection Agency (EPA). Retrieved 29 April 2012.
- EPA. "Clean Air Act: Title VI - Stratospheric Ozone Protection." Updated 2008-12-19.
- EPA (1990). New Source Review Workshop Manual: Prevention of Significant Deterioration and Nonattainment Area Permitting.
- "Clean Air Act: Title II - Emission Standards for Moving Sources". EPA. Retrieved 30 April 2012.
- Kiera Butler (March 7, 2011). "Do Green Cars Just Make People Drive More?". Mother Jones. Retrieved 23 December 2012.
- Trendowski, John. "Sustainability Trends — Reducing Emissions at Airports". Airport Magazine. Retrieved 22 April 2012.
- "Aircraft Emissions Expected to Grow, but Technological and Operational Improvements and Government Policies Can Help Control Emissions". U.S. Government Accountability Office. Retrieved 22 April 2012. Report no. GAO-09-554.
- "Clean Air Act". Cornell University Law School. Retrieved 22 April 2012.
- "www.biodiesel.org". The Clean Air Act's Clean-Fuel Vehicle Program. Retrieved 10 March 2012.[dead link]
- “Title III: General” Clean Air Act, United States. The Earth Encyclopedia. Updated: Apr 12, 2011. http://www.eoearth.org/article/Clean_Air_Act,_United_States
- CAA section 304, 42 U.S.C. § 7604.
- “ Title IV: Acid Deposition Control.” Clean Air Act, United States. The Earth Encyclopedia. Updated: Apr 12 2011. http://www.eoearth.org/article/Clean_Air_Act,_United_States#gen4
- EPA. "Permits and Enforcement." The Plain English Guide to the Clean Air Act. Revised 2011-11-08.
- EPA (February 1998). "Air Pollution Operating Permit Program Update: Key Features and Benefits." Document no. EPA/451/K-98/002. p. 1.
- EPA. "Protecting the Stratospheric Ozone Layer." The Plain English Guide to the Clean Air Act. Revised 2011-11-08.
- “ Title VI: Stratospheric Ozone Protection.” Clean Air Act, United States. The Earth Encyclopedia. Updated: Apr 12 2011. http://www.eoearth.org/article/Clean_Air_Act,_United_States#gen2
- Clean Air Act of 1963, P.L. 88-206, 77 Stat. 392, 1963-12-17.
- Jacobson, Mark Z. (2002). Atmospheric Pollution: History, Science, and Regulation. Cambridge University Press. ISBN 978-0-521-01044-3.
- EPA. "History of the Clean Air Act." Updated 2010-11-16.
- Clean Air Act Extension of 1970, 84 Stat. 1676, P.L. 91-604, 1970-12-31.
- EPA. "National Ambient Air Quality Standards (NAAQS)." Updated 2011-04-18.
- "Muskie Act". Toyota Motor Corp.
- EPA. "Module 7: Regulatory Requirements - The Clean Air Act." Environmental Protection Agency. <http://www.epa.gov/apti/bces/module7/caa/caa.htm>.
- Clean Air Act Amendments of 1977, P.L. 95-95, 91 Stat. 685, 1977-08-07.
- EPA. "Reducing Toxic Air Pollutants." The Plain English Guide to the Clean Air Act. Revised 2011-11-08.
- Clean Air Act Amendments of 1990, P.L. 101-549, 104 Stat. 2399, 1990-11-15.
- EPA. "What Are the Six Common Air Pollutants?" Revised 2010-07-01.
- EPA (2011). "The Benefits and Costs of the Clean Air Act from 1990 to 2020. Final Report." (also known as the "Second Prospective Study.")
- Cushman Jr., John H. (June 26, 1997). "Clinton Sharply Tightens Air Pollution Regulations Despite Concern Over Costs". New York Times.
- Chebium, Raju (November 7, 2000). "U.S. Supreme Court hears clean air cases regarding smog and soot standards". CNN.
- Cushman Jr., John H. (June 25, 1997). "D'Amato Vows to Fight for E.P.A.'s Tightened Air Standards". New York Times.
- Greenhouse, Linda (2001-02-28). "E.P.A.'s Right to Set Air Rules Wins Supreme Court Backing". New York Times.
- Rhode Island General Law, Title 23, Chapter 23, Section 2 (RIGL 23-23-2).
- Texas Department of Transportation (2010). "Metropolitan Planning Funds Administration. Section 5: Planning Process Self-Certification." TxDOT Manual System.
- Nelson, Gabriel (2011-07-01). "D.C. Circuit Rejects EPA's Latest Guidance on Smog Standards". The New York Times.
- Nelson, Gabriel (2011-05-03). "Republicans seek to spare smoggy Calif. areas from punishment". Environment & Energy News (E&E Publishing).
- EPA (2010). "Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990–2008." Document no. 430-R-10-006. Office of Atmospheric Programs.
- Works related to Clean Air Act at Wikisource
- EPA's The Plain English Guide to the Clean Air Act
- EPA Enforcement and Compliance History Online