Definitions for "Clean Air Act Amendments of 1990"
The original Clean Air Act (CAA), signed into law in 1963, set emissions standards for stationary sources, like factories and power plants. The CAA was amended several times, most recently in 1990. These 1990 amendments established more stringent emissions standards for motor vehicles. Criteria pollutants included lead, hydrocarbons (HC), carbon monoxide (CO), sulfur dioxide (SO2), nitrogen oxides (NOx), and particulate matter (PM), as well as air toxicities. Among other provisions, the CAAA required certain metropolitan fleet operators to purchase increasingly larger numbers of clean-fuel vehicles.
A 1990 Federal law that identifies "mobile sources" (vehicles) as primary sources of pollution and calls for stringent new requirements in metropolitan areas and states where attainment of National Ambient Air Quality Standards (NAAQS) is, or could be, a problem.
The comprehensive federal legislation which establishes criteria for attaining and maintaining the federal standards for allowable concentrations and exposure limits for various air pollutants; the act also provides emission standards for specific vehicles and fuels.