The federal Clean Air Act lists six common "criteria" air pollutants that pose environmental and health risks. Nearly 200 other listed hazardous air pollutants, also called "air toxics," are known to cause cancer, other serious diseases, and birth defects. The Department of Environmental Protection (MassDEP) and U.S. Environmental Protection Agency (EPA) work together to reduce and control emissions of these pollutants from a range of sources.