When it comes to clean air in the United States, one of the most important pieces of legislation that made it possible is the Clean Air Act (CAA) of 1970.

Prior to CAA 1970, there were a few federal acts involving air pollution.¹ The first was the Air Pollution Control Act of 1955, which provided funds for federal research on air pollution. This was followed by CAA 1963, which established a federal program within the U.S. Public Health Service and authorized research into techniques for monitoring and controlling air pollution. In 1967, the Air Quality Act was enacted to expand federal government activities, including conducting the first-ever extensive ambient monitoring studies and stationary source inspections.