Clean Air Act Extension of 1970

The Clean Air Act Extension, written by Maine Sen. Edmund Muskie and signed into law by President Nixon on Dec. 31, 1970, was arguably the most significant air pollution control bill in American history. It required the newly formed Environmental Protection Agency to create and enforce regulations to protect people from airborne pollution known to be hazardous to our health — specifically targeting sulfur dioxide, nitrogen dioxide, particulate matter, carbon monoxide, ozone and lead.