Protecting Public Health and the Environment.

Air Toxics

Air toxics, also known as hazardous air pollutants, are a group of air pollutants that are known or suspected to cause serious health problems such as cancer, birth defects, lung damage, and nerve damage. Examples of air toxics include asbestos, chloroform, formaldehyde, mercury and nickel compounds, and perchloroethylene.


Asbestos is the name given to a number of naturally occurring fibrous silicate minerals mined for properties such as thermal insulation, chemical and thermal stability, and high tensile strength. Learn more.

Mercury in the Air

Mercury is a naturally occurring element present throughout the environment. When released into the air as a result of human activity, it can become an air toxic. Learn more.

Sources of Air Toxics

Scientists estimate that millions of tons of toxic pollutants are released into the air each year. Most air toxics originate from the following human-made sources:

  • Mobile (vehicles such as cars, trucks, and buses)
  • Stationary (industrial operations such as factories, refineries, and power plants)
  • Indoor (chemicals in items such as some building materials and cleaning solvents)

Some air toxics are also are released from natural sources such as volcanic eruptions and forest fires.

Recent studies on air toxics have focused on releases by a variety of small sources, including cars and trucks, construction machinery, printers, auto repair shops, and numerous other small businesses that use paints or chemical cleaners. Results indicate that although each of these activities may release only a small amount of toxic air pollution, the combined effect is significant in many cities.

Health Impacts of Air Toxics

People exposed to air toxics at sufficient concentrations and durations may have an increased chance of developing cancer or experiencing other serious health problems, including damage to the immune system as well as neurological, reproductive (reduced fertility), developmental, and respiratory problems.

People are exposed to toxic air pollutants in many ways:

  • Breathing contaminated air
  • Eating contaminated food products, such as fish from contaminated waters; meat, milk, or eggs from animals that fed on contaminated plants; and fruits and vegetables grown in contaminated soil on which air toxics have been deposited
  • Drinking water contaminated by toxic air pollutants
  • Ingesting contaminated soil. Young children are especially vulnerable because they often ingest soil from their hands or from objects they place in their mouths
  • Touching (making skin contact with) contaminated soil, dust, or water (for example, during recreational use of contaminated water bodies)

Once toxic air pollutants enter the body, some persistent toxic air pollutants accumulate in body tissues. Since predators typically accumulate even greater pollutant concentrations than their contaminated prey, people and other animals at the top of the food chain may be exposed to higher concentrations of toxics than are found in water, air, or soil alone.

Environmental Impacts of Air Toxics

Toxic pollutants in the air or deposited on soils or surface waters can impact the environment. Animals, like humans, can experience health problems if exposed to sufficient concentrations of air toxics over time. Numerous studies conclude that deposited air toxics are contributing to birth defects, reproductive failure, and disease in animals. Persistent toxic air pollutants are of particular concern in aquatic ecosystems because the pollutants accumulate in sediments and may bioaccumulate in tissues of animals at the top of the food chain to concentrations many times higher than in the water or air.

Toxic pollutants that mimic hormones also pose a threat to the environment. In wildlife such as birds, shellfish, fish, and mammals, exposure to DDT, dioxins, mercury, and other pollutants has been associated with decreased fertility, decreased hatching success, damaged reproductive organs, and altered immune systems.

What You Can Do to Reduce Air Toxics

  • Drive less. Many air toxics, like benzene, come from motor vehicle exhaust. Try carpooling, using public transportation, combining trips, avoiding drive-thrus, driving the speed limit, and keeping your vehicle well tuned and in proper working condition.
  • Use cleaner-burning gasoline in your vehicle.
  • Do not open-burn trash, leaves, or other yard waste, or use burn barrels.
  • When possible, avoid consumer products containing toxic compounds. Read and follow all safety instructions. Products containing toxic compounds sometimes state, "use in a well ventilated area." Look for less toxic alternative products.
  • Minimize wood stove use.

Regulation of Air Toxics

Air toxics are regulated by both state and federal programs. Idaho's Air Toxics Program regulates approximately 350 toxic air pollutants (TAPs), while EPA's federal program regulates 188 hazardous air pollutants (HAPs). Both TAPs and HAPs are referred to as air toxics.