Hazardous air pollutants (HAPs), also known as toxic air pollutants or air toxics, are air pollutants that are known or suspected to cause cancer or other serious health impacts. They are associated with elevated cancer levels and other adverse health effects, such as reproductive effects or birth defects. Examples of toxic air pollutants include asbestos, benzene, dioxin, methylene chloride, perchloroethylene, toluene and metals such as cadmium, chromium, lead compounds and mercury.
HAPs can be released to the environment from natural sources, such as volcanic eruptions and forest fires. However, most HAPs originate from human-made sources:
- Mobile sources: cars, trucks, buses
- Stationary sources: factories, refineries, power plants
- Indoor sources: some building materials and cleaning solvents
The U.S. Environmental Protection Agency (EPA) is working with state, local and tribal governments to reduce air emissions of 188 toxic air pollutants to the environment. Any facility emitting air pollutants above certain levels is required to obtain an air permit, which specifies the pollutant limits they must meet so our air quality remains within state and federal standards. State and federal law does not allow the owner/ operator to build or modify a stationary source unless they can demonstrate the project will not cause or contribute to a violation of all applicable state and federal rules, including the National Ambient Air Quality Standards, all of which are developed to be protective of public health.