Congress Amends the Clean Air Act

The 1970 Clean Air Act Amendments were enacted to abate the ambient air-pollution problem in the United States. The Environmental Protection Agency was given the authority to create and enforce regulations to protect human health.

Summary of Event

The Clean Air Act Amendments of 1970 were signed into law on December 31, 1970. Before this legislation, U.S. air-quality control efforts were largely decentralized. Various federal and state agencies reacted to situations addressing local concerns. This legislation was the federal government’s first effort to protect air quality in a comprehensive way, and enforcing this policy was the Environmental Protection Agency’s Environmental Protection Agency (EPA) first major responsibility. Clean Air Act Amendments (1970)
Clean Air Act (1963)
Environmental policy, U.S.;air pollution
[kw]Congress Amends the Clean Air Act (Dec. 31, 1970)
[kw]Clean Air Act, Congress Amends the (Dec. 31, 1970)
[kw]Air Act, Congress Amends the Clean (Dec. 31, 1970)
[kw]Act, Congress Amends the Clean Air (Dec. 31, 1970)
Clean Air Act Amendments (1970)
Clean Air Act (1963)
Environmental policy, U.S.;air pollution
[g]North America;Dec. 31, 1970: Congress Amends the Clean Air Act[11110]
[g]United States;Dec. 31, 1970: Congress Amends the Clean Air Act[11110]
[c]Laws, acts, and legal history;Dec. 31, 1970: Congress Amends the Clean Air Act[11110]
[c]Environmental issues;Dec. 31, 1970: Congress Amends the Clean Air Act[11110]
Nixon, Richard M.
[p]Nixon, Richard M.;environmental policy
Ruckelshaus, William D.

Air quality had presented problems in the United States for many years prior to the enactment of any federal policy. The first effective control of solid-fuel, stationary sources was initiated in 1940, in St. Louis, Missouri, where it was reported that pollution was so bad that it was not unusual to use street lamps and automobile headlights during midday in the winter. In 1947, the Los Angeles County Air Pollution Control District Los Angeles County Air Pollution Control District
Air Pollution Control District, Los Angeles County was organized, and regulations restricting emissions of smoke and sulfur dioxide were passed. In 1955, it was estimated that there were more than ten thousand communities in the United States in which air quality was a local problem. Perhaps the most publicized was Los Angeles, California, where the topography and prevailing atmospheric controls are conducive for stable atmospheric conditions. The Los Angeles problem was largely attributed to the high concentration of mobile sources, that is, automobiles.

The federal government’s role in protecting air quality became more prevalent with the Air Pollution Control Act Air Pollution Control Act (1955) of 1955. This act assigned research, technical assistance, and training programs to the Public Health Service Public Health Service, U.S. (PHS) division of the Department of Health, Education, and Welfare Department of Health, Education, and Welfare, U.S.;pollution (HEW). Five years later, PHS established an air pollution division that dealt with legal, administrative, economic, and social concerns. In 1963, PHS was given authority over interstate air-pollution problems and federal sources of air pollution under the Clean Air Act. Pollution control and abatement were emphasized.

The federal government became progressively more assertive in protecting the nation’s ambient air quality in the 1960’s. The 1963 Clean Air Act received its impetus from the notion that the nation’s population had become more concentrated in expanding metropolitan and urban areas. In formulating this policy, it was asserted that air pollutants had increased in complexity and posed a greater danger to the public health and welfare. It was further asserted that the prevention and control of air pollution at its source were primary responsibilities of states and local governments. Two years later, however, with the Clean Air Act Amendments of 1965, the federal government began setting emission standards and controlling more categories of sources.

In 1967, the Air Quality Act Air Quality Act (1967) was passed. Its major purpose was to prevent individual states from establishing their own standards for new motor vehicles. It also expanded air-pollution research programs, provided for planning and controlling programs on a regional basis, and required states to set air-quality standards conforming to criteria set by HEW. The secretary of HEW was given authorization to designate air-quality control regions throughout the country, even though states were still given primary responsibility for enforcing air-pollution standards within their geographic areas. The unsatisfactory progress under this approach, coupled with the first Earth Day activities in April, 1970, provided the impetus for the Clean Air Act Amendments of 1970.

The Clean Air Act Amendments of 1970 paralleled the establishment of the EPA. The EPA, headed by William D. Ruckelshaus, was given the authority to establish standards and to require states to develop implementation plans to meet those standards. The EPA was also given control over emissions from new stationary sources in an attempt to prevent polluting industries from migrating to less polluted states where standards might not be as stringent as in the more industrialized states. Prior to this legislation, federal air-pollution legislation had always viewed state and local governments as having the primary responsibility for dealing with air-pollution problems. Under the 1970 amendments, this power was limited to implementation plans to meet the national ambient (outdoor) air-quality standards.

Initially, the EPA resisted drawing up regulations to preserve air quality until it was ordered to do so by the courts following a suit initiated by the Sierra Club. Each state was given responsibility for ensuring that air-quality standards would be met within its geographic area. State Implementation Plans (SIPs) specified the manner in which ambient air-quality standards would be achieved and maintained. The EPA administrator was given the responsibility for approving the SIPs.

Public input into SIPs was required. If a state did not hold public hearings on the SIPs in compliance with the legislation, the administrator was instructed to provide an opportunity for a hearing within the state.

Another important feature of the 1970 Clean Air Act Amendments dealt with emission standards for automobiles. It specified that 1975 model cars had to satisfy carbon monoxide and hydrocarbon standards by emitting no more than 10 percent of the emissions allowable for 1970 models, and that 1976 model cars had to have nitrogen-oxide emissions no more than 10 percent of those actually measured in 1971. The administrator of the EPA was empowered to permit a suspension of the standards for one year if necessary. After public hearings in 1973 at which the U.S. automobile manufacturers claimed they would be unable to meet the 1975-1976 standards, the EPA postponed compliance for one year even though three foreign manufacturers had vehicles that would meet the standards. Still another one-year postponement was obtained in 1974, to 1977-1978 models, by a section of the Energy Supply and Environmental Coordination Act.

To achieve the national ambient air-quality standards, in 1974 the EPA divided air areas into three classes: class 1, in which very little air-quality deterioration would be allowed; class 2, in which only moderate air-quality deterioration would be allowed; and class 3, in which more significant deterioration would be allowed as long as ambient standards were not exceeded. Mandatory class 1 areas were international parks, natural wilderness areas, national memorial parks that exceeded five thousand acres, and national parks that exceeded six thousand acres.

The 1970 amendments also had geographic implications. Increments and ceilings for pollutant concentrations over baseline air-quality levels were established for particulate matter and sulfur dioxide. In class 3 areas where baseline levels were low, the pollutant increments could be sustained, allowing growth to occur. Additional growth would be difficult in class 3 areas close to the national standards, as in older industrialized urban centers. No provision was made to allow construction of new sources or substantial expansion of old sources in nonattainment areas, areas that exceeded ambient air-quality standards, after 1975. The lack of such a provision would have impeded economic development in some areas. An emission-offset policy to deal with the problem of new or expanded sources proposed by the EPA was not adopted until 1975.


The Clean Air Act Amendments of 1970 helped change the national attitude toward the environment and the federal government’s role in environmental protection. This new attitude suggested that environmental protection and economic development could be accomplished concurrently. This legislation, in juxtaposition with economic, social, political, and technical developments, has greatly influenced air quality in the United States.

In response to the Clean Air Act Amendments of 1970, the EPA set national standards for the six most prevalent air pollutants: sulfur dioxide, nitrogen oxides, carbon monoxide, particulate matter, hydrocarbons, and lead. According to a report by the National Council on Environmental Quality, annual emissions of lead declined by 96 percent between the 1960’s and the 1990’s, mainly because of the phaseout of leaded gasoline. Furthermore, total national hydrocarbons and carbon monoxide emissions declined by 28 percent and 38 percent, respectively. This progress in controlling air pollution is especially noteworthy because the motor-vehicle population has grown faster than the human population—between 1970 and the mid-1990’s, the number of vehicle miles traveled doubled from one trillion to two trillion miles.

The 1970 act changed the way government does business with the private sector. It allowed indirect enforcement power by prohibiting federal agencies from obtaining goods, materials, or services from a source convicted of intentional violation of emission standards. In 1971, President Richard M. Nixon issued a presidential order prohibiting federal assistance to facilities not complying with the standards. Agencies such as Housing and Urban Development (HUD) and the Federal Highway Administration required that construction be compatible with the 1970 Clean Air Act.

The 1970 Clean Air Act Amendments evolved from many earlier attempts to solve a national problem, the declining quality of the nation’s air resources. Because the 1970 act was the first national effort to control and, when necessary, enforce air-quality standards, there was some apprehension about the policy’s success, but air-quality monitoring data indicate that the nation’s air quality has been improving since the enactment of the 1970 Clean Air Act Amendments. Clean Air Act Amendments (1970)
Clean Air Act (1963)
Environmental policy, U.S.;air pollution

Further Reading

  • Berry, Brian, and Frank E. Horton. “Managing Air Resources.” In Urban Environmental Management: Planning for Pollution Control. Englewood Cliffs, N.J.: Prentice Hall, 1974. This chapter, aimed at environmental planning, traces the development of air-pollution control in the United States, with an emphasis on the 1970 Clean Air Act Amendments.
  • Council on Environmental Quality. Fourth Annual Report on Environmental Quality. Washington, D.C.: Government Printing Office, 1973. This report discusses the implementation of the 1970 Clean Air Act Amendments. It focuses on the emergence of indirect and secondary impacts of air-pollution control on urban transportation, energy, land use, and the economy. Environmental quality reports are produced each year under the provisions of the 1969 Environmental Protection Act.
  • Greenberg, Michael J., et al. “Air Resources.” In A Primer on Industrial Environmental Impact. Piscataway, N.J.: Center for Urban Policy Research, Rutgers University, 1979. Provides a basic understanding of air pollution and methods of measuring the impact of industrial development on air quality.
  • GreenFacts. “Scientific Facts on Air Pollution: Particulate Matter, Ozone, and Nitrogen Dioxide.” Available at GreenFacts, a nonprofit organization based in Belgium, provides summaries of scientific articles on environmental and health topics to nonspecialists. This article outlines a 2003 World Health Organization report on ambient air pollution in Europe; relevant to pollution concerns in the United States as well.
  • Hosansky, David. The Environment, A to Z. Washington, D.C.: CQ Press, 2001. An encyclopedic work that includes entries on air quality, the Clean Air Act, the Environmental Protection Agency, global warming, and ozone depletion, particulate matter, and smog.
  • Paul, John A. “Urban Air Quality: The Problem.” EPA Journal 17 (January/February, 1991): 24-26. A brief, straightforward article that addresses the issue of why more progress has not been made in solving air-pollution problems since the 1970 Clean Air Act Amendments. Also offers possible solutions for abating air pollution.
  • Rogers, Paul G. “The Clean Air Act of 1970.” EPA Journal 16 (January/February, 1990): 21-23. A review of the 1970 Clean Air Act Amendments as they relate to earlier and later air-quality legislation. Congress’s view is articulated by the author, who chaired the House Subcommittee on Health and the Environment during the 1970 Clean Air Act Amendments deliberations.
  • Thierman, Alan. “Air Pollution and the Expanding Consumption of Fuels in Internal Combustion Engines.” In Environmental Side Effects of Rising Industrial Outputs, edited by Alfred J. Van Tassel. Lexington, Mass.: D. C. Heath, 1970. A recapitulation of the events leading up to the 1970 Clean Air Act Amendments, including federal and state legislation. Emphasis is on the automobile as a major air polluter.

Black Wednesday Demonstrates Dangers of Smog

Pennsylvania Town Suffers Deadly Temperature Inversion

Soviet Union Adopts Measures to Reduce Air Pollution

North Sea Flood Kills Nearly Two Thousand People in Holland

Congress Passes the Air Pollution Control Act

Mumford Warns of the Dangers of Growing Cities

Bookchin Warns of Health Hazards of Artificial Environments

Clean Air Act Grants Federal Authority to Regulate Air Pollution

Bookchin Publishes Crisis in Our Cities

Congress Passes the Motor Vehicle Air Pollution Control Act

Greenhouse Effect Is First Predicted

Pittsburgh Residents Form the Group Against Smog and Pollution