The Clean Air Act

The Clean Air Act Amendments of 1970 serve as the principal source of statutory authority for controlling air pollution and establish the basic United States program for controlling air pollution. The CAA Amendments require EPA to set National Ambient Air Quality Standards (NAAQS) for certain pollutants (criteria pollutants); to develop programs to address specific air quality problems; establish EPA enforcement authority; and provides for air quality research. These amendments placed the major responsibility for achieving NAAQS by 1975 on the states via their implementation plans. To support the States Implementation Plans (SIPs) the CAA requires the EPA to provide technical assistance. In one support program, EPA establishes Control Techniques Guidelines (CTGs) for controlling air pollutants for specific industries. For stationary sources, the act requires EPA to establish New Source Performance Standards (NSPS) for all major categories of polluting facilities. To regulate toxic or hazardous air pollutants (HAPs) the act provides the National Emissions Standards for Hazardous Air Pollutants (NESHAPs). The act also established the Federal Motor Vehicle Emission Standards. The principal result of implementation of the 1970 CAA Amendments was the establishment of the basic air quality management (AQM) system and organization in this country.

The Clean Air Act of 1970 was amended in 1977. The 1977 Clean Air Act Amendments added the "Prevention of Significant Deterioration" (PSD) and "Nonattainment Provisions" to the Act. These Provisions established the New Source Review (NSR) program for construction and modification of new major sources. For those areas that have not attained NAAQS, the 1977 CAA Amendments provided a much longer and realistic time frame for states to achieve compliance with the NAAQS.

In 1990, Congress once again amended the Clean Air Act. The passage of the 1990 amendments marked an overall change in the federal approach to air pollution. The new legislation placed renewed emphasis on controlling emissions of hazardous air pollutants and introduced efforts aimed at controlling acid rain and ozone depletion in the atmosphere. Five major goals for protecting and promoting human health and public welfare are identified in the CAA as amended (Air Quality Management in the United States, Report of The National Research Council, 2004):

• Mitigating potentially harmful human and ecosystem exposure to six criteria pollutants;
• Limiting the sources of and risks from exposure to HAPs, which are also called air toxics;
• Protecting and improving visibility impairment in wilderness areas and national parks;
• Reducing the emissions of species that cause acid rain, specifically SO2 and NOx;
• Curbing the use of chemicals that have the potential to deplete the stratospheric O3 layer.

The CAA prescribes a set of responsibilities and relationships among federal, state, tribal and local agencies in order to achieve air pollution control. EPA and the states are jointly charged with protecting the nation's environment. To meet this challenge, EPA and the states are striving to build the kind of open, productive relationship that will facilitate effective, joint management of the nation's environmental agenda.

An electronic version of the CAA can be found at
http://www.epa.gov/oar/caa/

A plain language guide to the act can be also found at
http://www.epa.gov/air/caa/peg/

The federal government's role is coordinated by EPA and is intended in part to provide a degree of national uniformity in air quality standards and approaches to pollution mitigation so that all individuals are assured a basic level of environmental protection. State and local governments are given much of the responsibility for implementing and enforcing the federal mandated rules and regulations within their jurisdictional domains, including developing and implementing specific strategies and control measures to meet national air quality standards and goals. Most federal environmental statutes embrace the concept that states should have primary responsibility for operating regulatory and enforcement programs. Today most states carry out basic regulatory and enforcement functions of traditional environmental programs as well as innovative new approaches to address particular state and local needs.