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Criteria Air Pollutants

The Clean Air Act requires EPA to set National Ambient Air Quality Standards (NAAQS)National Ambient Air Quality Standards established by EPA for six "criteria" pollutants in outdoor air. NAAQS are currently set for carbon monoxide, lead, ground-level ozone, nitrogen dioxide, particulate matter, and sulfur dioxide. for six common air pollutants (also known as "criteria air pollutantsThese pollutants are particulate matter, photochemical oxidants (including ozone), carbon monoxide, sulfur oxides, nitrogen oxides and lead. EPA calls these pollutants “criteria” air pollutants because it sets NAAQS for them based on the criteria, which are characterizations of the latest scientific information regarding their effects on health or welfare."). These pollutants are found all over the U.S. They can harm your health and the environment, and cause property damage.

Learn how EPA sets, reviews and revises standards (primary standardsNational ambient air quality standards designed to protect public health with an adequate margin for safety. and secondary standardsNational ambient air quality standards designed to protect the public welfare from adverse effects, including those related to effects on soils, water, crops, vegetation, man-made (anthropogenic) materials, animals, wildlife, weather, visibility, and climate; damage to property; transportation hazards; economic values, and personal comfort and well-being.), determines whether areas meet the standards, and works with areas to attain and maintain the standards.

Ground-level Ozone

ozone
  • Ozone Pollution
  • Setting and Reviewing Standards
  • Scientific and Technical Documents
  • Implementing the Standards
  • Air Quality Designations

Particulate Matter

particulate matter
  • Particle Pollution
  • Setting and Reviewing the Standards
  • Scientific and Technical Documents
  • Implementing the Standards
  • Air Quality Designations

Carbon Monoxide

carbon-monoxide
  • Carbon Monoxide Pollution
  • Setting and Reviewing Standards
  • Scientific and Technical Documents
  • Implementing the Standards
  • Air Quality Designations

Lead

lead
  • Lead Pollution
  • Setting and Reviewing Standards
  • Scientific and Technical Documents
  • Implementing the Standards
  • Air Quality Designations

Sulfur Dioxide

sulfur dioxide
  • Sulfur Dioxide Pollution
  • Setting and Reviewing Standards
  • Scientific and Technical Documents for Primary Standards
  • Scientific and Technical Documents for Secondary Standards
  • Implementing the Standards
  • Air Quality Designations

Nitrogen Dioxide

nitrogen dioxide
  • Nitrogen Dioxide Pollution
  • Setting and Reviewing Standards
  • Scientific and Technical Documents for Primary Standards
  • Scientific and Technical Documents for Secondary Standards
  • Implementing the Standards
  • Air Quality Designations

Resources

  • Current NAAQS Table 
  • AirNow - Air Quality Forecast
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  • State Implementation Plan Status Tools

Related Information

  • Air Quality Management Process
  • Clean Air Act
  • Hazardous Air Pollutants
  • Indoor Air Quality
  • Permitting Under the Clean Air Act
  • Regional Consistency
  • Technical Air Pollution Resources
  • Visibility and Haze
Contact Us to ask a question, provide feedback, or report a problem.
Last updated on August 9, 2022
United States Environmental Protection Agency

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