Clean Air Act

IN RESPONSE TO GROWING concern for the quality of the environment, the Clean Air Act (CAA), first passed in 1970 and amended substantially in 1990, has grown from its original set of guidelines for states to regulate sources of air pollution to specific air-quality requirements and regulatory programs.

Authorized by the CAA of 1970, the Environmental Protection Agency (EPA) established the National Ambient Air Quality Standards (NAAQS), which was the traditional centerpiece of CAA regulations. The NAAQS addresses six pollutants that threaten public health and welfare: sulfur dioxide, nitrogen oxides, particulate matter, carbon monoxide, ozone, and lead. All states and cities and towns in the United States must have levels of these pollutants beneath the ceilings required by the NAAQS or face substantial “nonattainment” fines and ...