Clean Air Act Overview

Clean Air Act Requirements and History

Congress designed the Clean Air Act to protect public health and welfare from different types of air pollution caused by a diverse array of pollution sources.

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Congress established much of the basic structure of the Clean Air Act in 1970, and made major revisions in 1977 and 1990. Dense, visible smog in many of the nation's cities and industrial centers helped to prompt passage of the 1970 legislation at the height of the national environmental movement.  The subsequent revisions were designed to improve its effectiveness and to target newly recognized air pollution problems such as acid rain and damage to the stratospheric ozone layer.

This page provides a brief introduction to the Clean Air Act, links to more detailed information on the law's requirements, and links to information on its history.

Control of common pollutants

To protect public health and welfare nationwide, the Clean Air Act requires EPA to establish national ambient air quality standards for certain common and widespread pollutants based on the latest science. EPA has set air quality standards for six common "criteria pollutants": particulate matter (also known as particle pollution), ozone, sulfur dioxide, nitrogen dioxide, carbon monoxide, and lead.

States are required to adopt enforceable plans to achieve and maintain air quality meeting the air quality standards.   State plans also must control emissions that drift across state lines and harm air quality in downwind states.

Other key provisions are designed to minimize pollution increases from growing numbers of motor vehicles, and from new or expanded industrial plants.  The law calls for new stationary sources (e.g., power plants and factories) to use the best available technology, and allows less stringent standards for existing sources.

Other air pollution problems targeted by Congress

The Act also contains specific provisions to address:

Pollution problems emerging after enactment

In addition to creating programs to solve identified pollution problems, Congress drafted the Act with general authorities that can be used to address pollution problems that emerge over time, such as greenhouse gases that cause climate change.

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Clean Air Act Text and Summaries

For description of CAA requirements, see the following resources: