Clean Air Act (CAA), US

Abstract

The Clean Air Act (CAA) is a federal legislation that established the basic structure that regulates air emissions from stationary and mobile sources in the United States and defines responsibilities for protecting and improving the nation's air quality and the stratospheric ozone layer. With the initial legislation in 1963, the U.S. Secretary of Health, Education, and Welfare, and the Air Pollution Office of the U.S. Public Health Service administered the program. With the creation of the Environmental Protection Agency in 1970, the responsibility to establish National Ambient Air Quality Standards (NAAQS) to protect public health and public welfare and to regulate emissions of hazardous air pollutants of the program was transferred the EPA. The CAA under NAAQS set pollutant standards and directed the states to develop state implementation plans, applicable to appropriate industrial sources in the state, in order to achieve these standards. CAA was amended in 1977 and 1990 primarily to set new goals (dates) for achieving attainment of NAAQS since many areas of the country had failed to meet the deadlines established in the original legislation. Section 112 of the CAA addresses emissions of hazardous air pollutants. The 1990 CAA Amendments revised Section 112 to first require issuance of technology-based standards for major sources and certain area sources. These emission standards are commonly referred to as maximum achievable control technology (MACT) standards which must be reviewed for adequacy 8 years after the technology-based MACT standards are issued for a source category.