The Clean Air Act of 1970 is a U.S. federal law intended to reduce air pollution and protect air quality. The act—which underwent major revisions in 1990 and 2003—deals with ambient air pollution (that which is present in the open air) as well as source-specific air pollution (that which can be traced to identifiable sources, such as factories and automobiles). The Clean Air Act sets standards for air quality that limit the amount of various pollutants to specified levels. The Clean Air Act also sets deadlines for governments and industries to meet the standards. The federal Environmental Protection Agency (EPA) is ultimately responsible for establishing standards and enforcing the Clean Air Act, although much of the daily business of fighting air pollution takes place at the state and local levels.

The Clean Air Act affects American businesses in a number of ways. Polluting industries may be forced to control air pollution through end-of-pipe methods, which capture pollution that has already been created and remove it from the air. Or businesses may be required to implement preventative measures, which limit the quantity of pollutants produced in the course of their operations. The cost of compliance with Clean Air Act regulations can be high for companies but the cost to society of air pollution is also quite high. What is clear is that the Clean Air Act has been largely successful in reducing air pollution. According to a report by the National Center for Public Policy Research entitled Earth Day 2004 Fact Sheet, it has contributed to a reduction in total emissions of major air pollutants in the United States of 25 percent between 1970 and 2004, and this despite the fact that U.S. gross domestic product increased 42 percent during the same period.


The original version of the Clean Air Act, which was passed by the U.S. Congress in 1970, was fairly straightforward. It placed the Environmental Protection Agency in charge of monitoring and improving the nation's air quality. The EPA's powers under the act included establishing research programs, setting clean air standards, enforcing regulations, and providing technical and financial assistance to state and local government efforts toward reducing air pollution. The 1970 act also directed the EPA to establish National Ambient Air Quality Standards (NAAQS) to control the emission of a number of substances that threatened air quality. The NAAQS divided pollutants into two categories: primary pollutants, or those directly affecting human health; and secondary pollutants, or those indirectly affecting human welfare.

The Clean Air Act underwent significant changes and amendments in 1990. The amendments brought widespread reform to the government's methods of dealing with all kinds of air pollution. For example, the 1990 revisions specifically targeted acid rain, with the goal of reducing the emissions of sulfur dioxide and nitrogen oxides by half. The reforms also established new limits on ozone—a prime contributor to smog—in urban areas. Cities that failed to meet the regulations were divided into five different categories of non-attainment areas, with specific ozone emission goals for each category. Another change to the act addressed the depletion of the protective ozone layer in the earth's atmosphere. It mandated the gradual phasing out of chlorofluorocarbons (CFCs) and other ozone-depleting chemicals.

The Clean Air Act of 1990 also placed new regulations on automobile emissions. It set targets for reducing the emissions of hydrocarbons and nitrogen oxides by vehicles and assembly plants. It also required new automobiles to meet stricter pollution standards, whether by installing pollution control equipment like catalytic converters or by burning cleaner fuels. Another major provision of the Clean Air Act dealt with toxic air pollutants. The 1990 amendments expanded the number of regulated substances from 7 to 189, set safety standards for factories where toxic chemicals were used or emitted, and required polluters to install the best available pollution control equipment.

In early 2003 a new law to amend the Clean Air Act was introduced before the Senate. The proposed law, entitled the Clear Skies Act of 2003, is based on an initiative by the same name put forward by President George W. Bush. The Clear Skies Act is controversial because it proposes amending the Clean Air Act substantially, changing many of the mandated emission reduction goals and altering the way in which emission controls would be implemented. According to one of the bill's sponsors, Senator James Inhofe, Republican of Oklahoma, "Moving beyond the confusing, command-and-control mandates of the past, Clear Skies cap-and-trade system harnesses the power of technology and innovation to bring about significant reductions in harmful pollutants." As of early 2006, the Clean Air Act remains in committee, having failed to garner enough support to be passed into law.


In 1997, the EPA established strict new regulations to control the release of ozone and particulates, two dangerous pollutants that agency experts believed are responsible for killing thousands of Americans each year. In fact, Business Week reported that EPA estimates showed that the new rules could prevent 15,000 premature deaths, 350,000 cases of asthma, and one million cases of impaired lung function annually, in addition to saving billions of dollars in health care costs.

But business groups felt that the new regulations were too broad and would impose excessive compliance costs on industry. Associations representing a number of different industries joined in suing to overturn the EPA rules. They argued that the agency had overstepped its authority in imposing the restrictions under the Clean Air Act, and had thus infringed on the constitutional power of Congress to pass laws. The industry groups also argued that the EPA should be forced to consider the costs as well as the benefits of such actions.

The lawsuit, Browner v. American Trucking Associations, went before the U.S. Supreme Court in the fall of 2000. In arguments before the court, the EPA claimed that it was banned by a 20-year-old federal court ruling from considering costs when imposing new regulations. In 2001 the Supreme Court upheld this argument, ruling in favor of the EPA.


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"Earth Day 2004 Fact Sheet." The National Center for Public Policy Research. Available from Retrieved on 24 January 2006.

Hess, Glenn. "Supreme Court Examines Arguments Concerning Clean Air Act Regulations." Chemical Market Reporter. 13 November 2000.

Kilian, Michael. "Bush Administration Pushes Plan to Change Air Pollution Regulation." Chemical Market Reporter. Chicago Tribune, 27 January 2005.

Marriott, Betty Bowers. Environmental Impact Assessment: A Practical Guide. McGraw-Hill, 1997.

"Regulators: By Whose Authority?" Business Week. 16 October 2000.

Trzupek, Richard. Air Quality Compliance and Permitting Manual. McGraw-Hill Professional, 2002.

Varva, Bob. "The 1970 Clean Air Act Changes Rules on Fuels and the Environment." National Petroleum News. August 2000.