High Quality Content by WIKIPEDIA articles! The Clean Air Act is a United States federal law enacted by Congress, and signed by President Richard Nixon on December 31, 1970 to control air pollution on a national level. It requires the Environmental Protection Agency (EPA) to develop and enforce regulations to protect the general public from exposure to airborne contaminants that are known to be hazardous to human health. The Act was passed in 1963 and significantly amended in 1970, 1977 and 1990.