What Are Toxic Air Pollutants?

Toxic, or hazardous, air pollutants are substances that cause or are suspected of causing cancer, birth defects, or other serious harms. They can be gases, such as hydrogen chloride, benzene and toluene or compounds and metals such as asbestos, cadmium, mercury and chromium. The U.S. Environmental Protection Agency has classified 188 pollutants as hazardous.

Just because a pollutant is not listed on the list as "hazardous" does not mean that it does not cause cancer or is safe to breathe, however. Other air pollutants like particle pollution can also cause cancer or other serious hazards.

What Are the Health Effects from Toxic Air Pollutants?

Toxic air pollutants pose different risks to health depending on the specific pollutant, including:

  • Cancer, including lung, kidney, bone, stomach
  • Harm to the nervous system and brain
  • Birth defects
  • Irritation to the eyes, nose and throat
  • Coughing and wheezing
  • Impaired lung function
  • Harm to the cardiovascular system
  • Reduced fertility

How Are People Exposed to These Pollutants?

People inhale many of these pollutants in the air where they live. But, because these pollutants also settle into waterways, streams, rivers and lakes, people can drink them in the water or eat them in the fish from these waters. Some hazardous pollutants settle into the dirt that children play in and may put in their mouths.

Where Do Toxic Air Pollutants Come From?

Major sources of toxic air pollutants outdoors include emissions from coal-fired power plants, industries, and refineries, as well as from cars, trucks and buses.

Certain industries also produce specific air toxins. For example, ethylene oxide leaks from facilities that sterilize medical equipment as well as from other industrial sources. 

Fortunately, thanks to the Clean Air Act, many of these sources are being cleaned up, though more remains to be done.

Chemical releases, such as accidents at industrial facilities or when hazardous materials are being transported, can also result in air toxics being released into the air. 

Indoor air also can contain hazardous air pollutants from sources that include tobacco smoke, building materials like asbestos, and consumer products like cleaning supplies and air fresheners. 

Find information about air toxics in your community

EPA has two nationwide databases that provide information on emissions near you.

  • National Air Toxics Assessment – This site reports on 33 air toxics that EPA rates as the greatest threat to public health in the largest number of urban areas. Available information includes maps and lists by state or county level.
  • Toxics Release Inventory – Type in your zip code and learn about releases of toxic chemicals into the environment through the air, water, and land from manufacturing facilities.

Toxic Air: The Case for Cleaning Up Coal-fired Power – 2011 Lung Association report that . describes the hazardous air pollutants from coal-fired power plants.

Emissions of Hazardous Air Pollutants from Coal-fired Power Plants – the technical document that underlies the Lung Association’s “Toxic Air” report.

Page last updated: October 25, 2023

Freedom From Smoking Clinic
Detroit, MI | May 29, 2024
Asthma Basics Workshop - National
, | Jun 18, 2024