Air Toxics (Hazardous Air Pollutants)
Pollutants known or suspected to cause cancer, birth defects, or other serious health effects, regulated separately from criteria pollutants.
Detailed Explanation
Air toxics, also known as hazardous air pollutants (HAPs), are pollutants that are known or suspected to cause cancer, birth defects, reproductive effects, or other serious health effects. Unlike the six criteria pollutants, which are common and widespread, air toxics are typically emitted in smaller quantities by specific industrial sources. The Clean Air Act identifies 187 hazardous air pollutants, including benzene (found in gasoline), perchloroethylene (used in dry cleaning), methylene chloride (an industrial solvent), dioxins, asbestos, toluene, and metals such as mercury, cadmium, and chromium compounds. The EPA regulates air toxics through the National Emission Standards for Hazardous Air Pollutants (NESHAP), which require major sources to install Maximum Achievable Control Technology (MACT). The EPA also conducts the National Air Toxics Assessment (NATA), which estimates cancer risk and other health risks from air toxics exposure across the country. Unlike criteria pollutants, air toxics are not included in the AQI calculation, so elevated air toxics levels are invisible in standard AQI readings. AirHistory focuses on criteria pollutants as reported in the EPA's AQS annual dataset. However, for communities near industrial facilities, air toxics may pose health risks that are not reflected in AQI data, residents can consult the EPA's NATA and Toxics Release Inventory (TRI) for information specific to their area.
Related Terms
Criteria Pollutants
The six common air pollutants regulated by the EPA under the Clean Air Act: ozone, PM2.5, PM10, CO, NO2, and SO2.
Clean Air Act
The primary federal law governing air quality in the United States, first enacted in 1963 and significantly amended in 1970 and 1990.
EPA Air Quality System (AQS)
The EPA's national database of ambient air quality data collected from monitoring stations across the United States.
Volatile Organic Compounds (VOCs)
Carbon-containing chemicals that easily evaporate at room temperature and contribute to ozone formation and direct health effects.
Frequently Asked Questions
Pollutants known or suspected to cause cancer, birth defects, or other serious health effects, regulated separately from criteria pollutants.
Air toxics, also known as hazardous air pollutants (HAPs), are pollutants that are known or suspected to cause cancer, birth defects, reproductive effects, or other serious health effects. Unlike the six criteria pollutants, which are common and widespread, air toxics are typically emitted in smaller quantities by specific industrial sources. The Clean Air Act identifies 187 hazardous air pollutants, including benzene (found in gasoline), perchloroethylene (used in dry cleaning), methylene chloride (an industrial solvent), dioxins, asbestos, toluene, and metals such as mercury, cadmium, and chromium compounds.
this entity is one of the U.S. air quality and pollution monitoring concepts that recurs across this site. The definition above is the technical answer; the paragraphs below add the practical context for how the concept connects to the the EPA Air Quality System (AQS) data behind every per-entity page on the site.
In the the EPA Air Quality System (AQS) data, this concept shapes one or more of the fields that drive the per-entity grades and rankings on this site. The methodology page describes which fields feed into which output; this glossary entry documents the underlying term.