Define: Clean Air Act

The Clean Air Act is a comprehensive federal law enacted in the United States in 1970 to regulate air pollution and protect public health and the environment. It sets standards for air quality, establishes emission limits for pollutants, and requires states to develop plans to achieve and maintain these standards. The Act also provides the Environmental Protection Agency (EPA) with the authority to enforce these regulations and implement programs to reduce air pollution. Over the years, the Clean Air Act has been amended and expanded to address emerging environmental issues and promote cleaner technologies. It has played a crucial role in improving air quality, reducing harmful emissions, and mitigating the impacts of air pollution on human health and the environment.

The Clean Air Act (CAA) is a piece of legislation that establishes national guidelines for air pollution and its sources. It consists of two components: regulating air quality levels and regulating sources of pollution. The Environmental Protection Agency (EPA) is responsible for enforcing the CAA. The EPA is required by the CAA to identify and regulate pollutants emitted from various sources that pose a threat to public health. These pollutants are known as “criterion pollutants.” Currently, there are six criteria pollutants: ozone, carbon monoxide, sulphur dioxide, particulate matter, nitrogen dioxide, and lead. The EPA regularly considers adding pollutants to the criteria list. Criteria pollutants are subject to the National Ambient Air Quality Standards (NAAQS). NAAQS regulations mandate that any given pollutant must remain below a level that ensures public health protection with an adequate margin of safety. Areas that meet all NAAQS criteria for pollutant standards are referred to as Attainment Areas, while areas that fail to meet at least one criteria for pollutant standard are called Non-Attainment Areas. Attainment Areas and Non-Attainment Areas are subject to different standards and regulations. The CAA requires all states to develop a State Implementation Plan (SIP) outlining how they intend to enforce the NAAQS standards in their non-attainment areas. States have flexibility in choosing regulatory and non-regulatory measures to meet the required standards. If the EPA determines that a proposed SIP will not achieve the NAAQS requirements, they can establish a Federal Implementation Plan (FIP) and mandate the state to comply with it. The regulation of pollution under the CAA depends on whether the source of pollution is stationary or mobile. For stationary sources, the level of pollution control technology required depends on whether the area is an attainment area or a non-attainment area. Attainment areas require the use of Best Available Control Technology (BACT), while non-attainment areas have higher standards. New or modified major sources of air pollution in non-attainment areas must employ control technology with the lowest achievable emission rate (LAER), and existing sources must use reasonably available control technology (RACT). For mobile sources of air pollution, the EPA focuses on both the fuel used in vehicles and the emissions produced. Mobile sources of pollution, such as cars, tend to emit a significant amount of carbon dioxide, which is a non-criteria pollutant. However, the Supreme Court ruled in Mass v. EPA that the EPA has the authority to regulate carbon dioxide emissions from mobile sources and is obligated to do so. For instance, if a factory in a non-attempt area emits excessive sulphur dioxide, the state must develop a plan to reduce the emissions and meet the NAAQS standards. The state may require the factory to install new pollution control technology to achieve emission reductions. If the state’s plan is ineffective, the EPA can step in and create a plan, compelling the state to comply. Another example is the regulation of emissions from cars. The EPA establishes standards for the amount of pollutants that can be emitted from a car’s tailpipe and also sets standards for the fuel used in cars. These measures help reduce the amount of pollution emitted by vehicles into the air.

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This glossary post was last updated: 30th April 2024.