Jump to main content or area navigation.

Contact Us

Improving Air Quality in Your Community

Basic Information

Information provided for informational purposes onlyNote: EPA no longer updates this information, but it may be useful as a reference or resource.

This page provides basic information related to air toxics, health, and ecological effects by answering the following questions:

What are hazardous air pollutants?

  • Hazardous air pollutants (HAPs) are those pollutants that are known or suspected to cause cancer or other serious health effects, such as:
    • Reproductive effects.
    • Birth defects.
    • Adverse environmental effects.
  • HAPs are often referred to as "toxics" or "air toxics."
  • The Clean Air Act contains a list of HAPs to be regulated by EPA.
  • EPA is working with state, local, and tribal governments to reduce emissions of HAPs. Examples of HAPs include
    • Benzene, which is found in gasoline.
    • Perchlorethylene, which is emitted from some dry cleaning facilities.
    • Methylene chloride, which is used as a solvent and paint stripper by a number of industries.
    • Dioxins form during combustion, waste incineration, metal smelting, and chlorine bleaching and manufacturing processes.
    • Asbestos, while naturally occurring, causes health effects through exposure to building materials, paper products, plastics, and other products.
    • Toluene is added to gasoline, used to produce benzene, and used as a solvent.
    • Metals such as cadmium, mercury, chromium, and lead compounds are found in nature, used in many products, and are emitted during combustion, waste incineration, and smelting processes.

Top of page

What are the health and environmental effects of hazardous air pollutants?

  • People exposed to HAPs at sufficient concentrations and durations may have an increased chance of getting cancer or experiencing other serious health effects. These health effects can include:
    • Damage to the immune system.
    • Neurological problems.
    • Reproductive problems (e.g., reduced fertility).
    • Developmental problems.
    • Respiratory problems.
  • In addition to exposure from breathing air toxics, some HAPs such as mercury can deposit onto soils or surface waters, where they are absorbed by plants and ingested by animals and are readily absorbed in fatty tissues and accumulate in the body fat. The concentration of these pollutants eventually become more concentrated as they move up the food chain, especially into larger, longer-living organisms.
  • Like humans, animals may experience health problems if exposed to sufficient quantities of air toxics over time.

Top of page

Where do hazardous air pollutants come from?

  • Most air toxics originate from human-made sources, including:
    • Mobile sources (e.g., cars, trucks, buses).
    • Stationary sources (e.g., factories, refineries, power plants).
    • Indoor sources (e.g., some building materials and cleaning solvents).
  • Some air toxics are released from natural sources such as volcanic eruptions and forest fires.

Top of page

How are people exposed to hazardous air pollutants?

  • People can be exposed to HAPs in many ways, such as by:
    • Breathing contaminated air.
    • Eating contaminated food products, such as:
      • Fish from contaminated waters.
      • Meat, milk, or eggs from animals that fed on contaminated plants.
      • Fruits and vegetables grown in contaminated soil on which air toxics have been deposited.
    • Drinking water contaminated by HAPs.
    • 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 HAPs enter the body, some persistent HAPs accumulate in body tissues.
  • Predators typically accumulate even greater pollutant concentrations than their contaminated prey. As a result, people and other animals at the top of the food chain who eat contaminated fish or meat are exposed to concentrations that are much higher than the concentrations in the water, air, and soil.

Top of page

How can I find out about toxics in my community?

  • The National Air Toxics Assessment provides emissions and health risk information on 33 air toxics that present the greatest threat to public health in the largest number of urban areas. Maps and lists are available and can be requested by state or county level.
  • The Toxics Release Inventory is a database that includes information for the public about releases of toxic chemicals from manufacturing facilities in the environment through air, water, and land. You can access the data by typing in your zip code.

Top of page

What progress has EPA made in reducing toxic emissions?

  • Controls for Industrial and Commercial Sources of Toxics
    • Air toxics are pollutants known, or suspected, to cause cancer and other health effects. Since 1990, EPA has issued 96 standards that require 174 industry source categories to eliminate 1.7 million tons of air toxics.
    • EPA has developed a booklet called Taking Toxics Out of the Air that describes these rules.
  • Controls for Cars and Trucks
    • EPA and state governments (e.g., California) have reduced emissions of benzene, toluene, and other air toxics from mobile sources by requiring the use of reformulated gasoline and placing limits on tailpipe emissions.
    • Important new controls for fuels and vehicles are expected to reduce selected motor vehicle air toxics from 1990 levels by more than 75% by 2020.
    • EPA has developed a Web site devoted to mobile source air toxics.
  • Indoor Air
    • EPA, in close cooperation with other Federal agencies and the private sector, is actively involved in efforts to better understand indoor air pollution and to reduce people's exposure to air pollutants in offices, homes, schools, and other indoor environments.
    • EPA has an office devoted to indoor air quality.

Top of page

What are the available resources on health and ecological effects?

Top of page

What other links are available for air toxics resources?

Top of page



Jump to main content.