Learn how air pollution can harm your health and the environment, and what EPA is doing to protect the air we breathe.

The Clean Air Act requires EPA to set National Ambient Air Quality Standards (NAAQS) for six common air pollutants (also known as “criteria air pollutants”).

Ozone can be “good” or “bad” for health and the environment depending on where it’s found in the atmosphere.

National Ambient Air Quality Standards (NAAQS) for ground-level ozone, or ozone pollution, specify a maximum allowed measurement for ozone (O3) to be present in outdoor air.