Examples include heavy metals such as cadmium, chromium, lead and mercury, and polycyclic aromatic hydrocarbons from the burning of fossil fuels and waste.

The act establishes federal standards for mobile sources of air pollution and their fuels and for sources of 187 hazardous air pollutants, and it establishes a cap-and-trade program for the emissions that cause acid rain. It establishes a comprehensive permit system for all major sources of air pollution.

Indoor Air Quality: EPA does not regulate indoor air, but we do offer assistance in protecting your indoor air quality.

The six pollutants are carbon monoxide, lead, ground-level ozone, nitrogen dioxide, particulate matter, and sulfur dioxide. The standards are set at a level that protects public health with an adequate margin of safety. for six common air pollutants (also known as "criteria air pollutants").