U.S. Congress Approves More Clean Air Act Amendments Summary

  • Last updated on November 10, 2022

The 1990 Clean Air Act provided comprehensive regulations designed to address some of the worst air-pollution problems in the United States, including problems related to hazardous pollutants and acid deposition.

Summary of Event

On November 15, 1990, President George H. W. Bush signed into law the Clean Air Act of 1990. This law was designed to improve and strengthen the regulations already established by the 1970 Clean Air Act Clean Air Act Amendments (1970) and its 1977 amendments, which had given the federal government authority to set national standards to protect human health and welfare. Clean Air Act (1990) Pollution;legislation Air pollution;legislation Environmental policy, U.S.;pollution [kw]U.S. Congress Approves More Clean Air Act Amendments (Nov. 15, 1990) [kw]Congress Approves More Clean Air Act Amendments, U.S. (Nov. 15, 1990) [kw]Clean Air Act Amendments, U.S. Congress Approves More (Nov. 15, 1990) [kw]Act Amendments, U.S. Congress Approves More Clean Air (Nov. 15, 1990) [kw]Amendments, U.S. Congress Approves More Clean Air Act (Nov. 15, 1990) Clean Air Act (1990) Pollution;legislation Air pollution;legislation Environmental policy, U.S.;pollution [g]North America;Nov. 15, 1990: U.S. Congress Approves More Clean Air Act Amendments[07920] [g]United States;Nov. 15, 1990: U.S. Congress Approves More Clean Air Act Amendments[07920] [c]Laws, acts, and legal history;Nov. 15, 1990: U.S. Congress Approves More Clean Air Act Amendments[07920] [c]Environmental issues;Nov. 15, 1990: U.S. Congress Approves More Clean Air Act Amendments[07920] Bush, George H. W. [p]Bush, George H. W.;environmental policy Byrd, Robert Dingell, John D. Mitchell, George

A series of events prompted passage of the legislation. After years of political obstacles to such an act, the political conditions were right: President Bush supported legislation, and Representative John D. Dingell, a Democrat from Michigan, had previously opposed similar legislation given his state’s connection with the automobile industry, but he was more open to the law after a compromise on motor vehicle emissions. There was also a new majority leader in the Senate, George Mitchell, who replaced Robert Byrd, a previous opponent. Mitchell supported clean-air legislation. The president’s chief of staff, John Sununu, Sununu, John former governor of New Hampshire, who had worked for air-pollution controls in the past, and William Reilly, Reilly, William head of the Environmental Protection Agency (EPA), known to have a strong environmental background, were also on board. These changes, all occurring between 1989 and 1990, appear to have been instrumental in the final passage of acid rain legislation.

One last influence must be mentioned: Canada. A scientific report released in 1979 confirmed what Canadians had been publicly stating for a long time: that U.S. sources contributed five times as much transboundary pollution in Canada as did Canadian sources. This concern spurred Canadians to use a multifaceted foreign policy approach in hopes of gaining U.S. reductions in emissions. Canada attempted to influence U.S. clean-air policy through quiet diplomacy (formal diplomatic avenues), interventionist public diplomacy (agreements and conferences), and personal diplomacy (interactions between the prime minister and the president) and by strengthening its own domestic environmental programs.

The 1990 Clean Air Act was divided into four main categories: attainment and maintenance of air-quality standards (smog), motor vehicles and alternative fuels, toxic air pollutants, and acid deposition (acid rain). Furthermore, the acid rain provision created a new market system allowing the trading of air-pollution allowances. Businesses that pollute below established standards may earn air-pollution credits which may then be sold to companies that pollute more than the federally mandated standards allow.

The provisions on ambient air quality (smog) directly affect ozone, carbon monoxide, and particulate matter. Cities that failed to meet standards for human health were allowed six years to come under compliance. An exception was made for Los Angeles, the most highly polluted city in the United States, which was given approximately twenty years to attain the new standards.

States were required to initiate or upgrade inspection and maintenance programs, install vapor recovery at gas stations, and otherwise reduce hydrocarbon and nitrogen oxide emissions from both small and major stationary sources. States were also mandated to adopt transportation controls that would offset the rapid growth in vehicle miles traveled. In addition, the new act strengthened the ability of the EPA and the states to enforce standards by requiring individual sources of pollution to meet their obligations within a single five-year operating permit. The states were given three years to develop permit programs and submit them to the EPA. Sources were required to pay permit fees covering the costs of operating the programs.

The provisions on motor vehicles centered on vehicle emissions, alternative fuels, and the production of “clean” cars. Manufacturers of 1994-model-year cars were required to reduce tailpipe emissions of hydrocarbons, carbon monoxide, and nitrogen oxides and to maintain these standards over a longer vehicle life. Requirements were put in place to ensure that reformulated gasolines would be used in cities with severe ozone problems and that gasoline blended with alcohol (oxyfuels) would be sold during winter months in those cities having the worst carbon monoxide problems. California was instructed to implement tighter emission limits through a combination of vehicle technology and clean fuels—substitutes for gasoline or blends of substitutes with gasoline.

In a departure from the 1970 law, Congress required emission limits for all major sources of hazardous or toxic air pollutants. Furthermore, Congress did not leave the determination of “toxic” and “hazardous” to the EPA but instead specifically listed 189 chemicals to be regulated. Congress required the EPA Environmental Protection Agency to list the categories of industrial processes in chemical plants, oil refineries, steel plants, and other facilities that emit these pollutants; to issue standards for each of the source categories by the deadlines specified; and to use as a basis the minimum regulatory standards provided in Title III of the law. Moreover, Congress required risk management plans for accidental release of air toxics and established the independent Chemical Safety Board Chemical Safety Board to investigate chemical accidents to determine their causes.

Title IV of the 1990 Clean Air Act centered on reducing the major precursors of acid rain Acid rain —sulfur dioxide and nitrogen oxide. A two-phase, market-based system was established to reduce sulfur dioxide emissions from power plants by more than half. Plants are issued allowances based on fixed emission rates set in the law and on their previous fossil-fuel use. They pay penalties if emissions exceed the allowances they hold. Allowances can be banked or traded. In phase 1, large high-emission plants located in eastern and midwestern states were mandated to achieve reductions by 1995. In phase 2, commencing on January 1, 2000, emission limits were imposed on smaller, cleaner plants and tightened on phase 1 plants. All sources were required to install continuous emission monitors to ensure compliance. Emissions of nitrogen oxides were to be reduced by two million tons a year from the 1980 levels.

The new act phased out production of chlorofluorocarbons Chlorofluorocarbons (CFCs), carbon tetrachloride, and methyl chloride by the year 2000 and methyl chloroform by the year 2002. Companies servicing air-conditioning for cars are required to purchase certified recycling equipment and to train employees to use this equipment. The EPA is directed to develop regulations requiring reduced emissions from all other refrigeration sectors to their lowest achievable levels. By November, 1992, use of CFCs in nonessential applications was prohibited. Finally, the act mandated warning labels on all containers and products (refrigerators, foam insulation) that enclose CFCs and other ozone-depleting chemicals.


The 1990 Clean Air Act was a notable achievement on several accounts. The law is considered the most comprehensive set of regulations ever developed to reduce air pollution. In this regard, it set up controls for three major pollution problems (CFCs, air toxics, and acid rain) that were not covered by the Clean Air Act of 1970 or the 1977 amendments. The 1990 act clearly limited administrative discretion by specifying the requirements and deadlines for the EPA, states, and regulated industries to come under compliance, and it provided marketlike incentives to encourage compliance. Clean Air Act (1990) Pollution;legislation Air pollution;legislation Environmental policy, U.S.;pollution

Further Reading
  • citation-type="booksimple"

    xlink:type="simple">Bryner, Gary C. Blue Skies, Green Politics: The Clean Air Act of 1990. Rev. ed. Washington, D.C.: Congressional Quarterly Press, 1995. Examines what Congress and the executive branch were trying to accomplish in revising the Clean Air Act. Provides an excellent summary of the major titles of the act and the regulatory changes they brought about.
  • citation-type="booksimple"

    xlink:type="simple">Cohen, Richard E. Washington at Work: Back Rooms and Clean Air. 2d ed. Newton, Mass.: Allyn & Bacon, 1994. Presents the story of the passage of the Clean Air Act from the perspective of an insider. Offers a glimpse into the behind-the-scenes operation of Congress.
  • citation-type="booksimple"

    xlink:type="simple">Doyle, Jack. Taken for a Ride: Detroit’s Big Three and the Politics of Air Pollution. New York: Four Walls Eight Windows, 2000. Addresses the automobile industry’s resistance to environmental regulations.
  • citation-type="booksimple"


    Environmental Law 21, no. 4 (1991). Entire issue provides one of the most comprehensive reviews available of the Clean Air Act of 1990, including a history of air-pollution regulation in the United States and a critique of the major provisions.
  • citation-type="booksimple"

    xlink:type="simple">Hollander, Jack M. The Energy-Environment Connection. Washington, D.C.: Island Press, 1992. Presents an overview of how environmental and energy problems are linked. Several chapters are devoted to the environmental impacts of air pollution and acid rain, with emphasis on how U.S. policy fits in with the policies of the rest of the world’s governments.
  • citation-type="booksimple"

    xlink:type="simple">Rosenbaum, Walter A. Environmental Politics and Policy. 6th ed. Washington, D.C.: Congressional Quarterly Press, 2004. Describes the policy and governmental settings that surrounded the passage of the 1990 Clean Air Act. Also discusses the interaction of science and technology with respect to regulatory change.
  • citation-type="booksimple"

    xlink:type="simple">Switzer, Jacqueline Vaughn. Environmental Politics: Domestic and Global Dimensions. 4th ed. Belmont, Calif.: Wadsworth, 2004. Uses the policy process as a framework for reviewing a broad spectrum of environmental problems, including urban air quality and the Los Angeles air-pollution problem.
  • citation-type="booksimple"

    xlink:type="simple">Vig, Norman J., and Michael E. Kraft. Environmental Policy in the 1990’s. 2d ed. Washington, D.C.: Congressional Quarterly Press, 1994. Provides a comprehensive look at environmental policy as it developed during the 1980’s and 1990’s. Includes an excellent chapter on environmental gridlock, especially as it applies to air quality and acid rain.

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Categories: History