Air pollutants

Air quality regulators generally view air pollutants in three categories: criteria pollutants, air toxics, and greenhouse gases.

Criteria pollutants

The Clean Air Act requires the US EPA to set National Ambient Air Quality Standards (NAAQS) for six common air pollutants, called “criteria pollutants”, to protect health, the environment, and property. The criteria pollutants are ground-level ozone, particulate matter, lead, nitrogen dioxide, carbon monoxide, and sulfur dioxide. Volatile organic compounds are also monitored, tracked, and controlled to help reduce ozone concentrations in our air, but do not have their own standards.

All states are required to meet these standards or develop plans to come into compliance. Minnesota is currently meeting all of the national standards. See monitoring results from all of Minnesota’s criteria pollutant monitoring sites on our Criteria Pollutant Data Explorer.

Air toxics

Air toxics are a group of pollutants that cause or may cause cancer or other serious health effects or adverse environmental and ecological effects. Air toxics are also known as Hazardous Air Pollutants (HAPs) which are specified in the Clean Air Act Amendments. There are no state or federal standards for individual air toxics, but the Clean Air Act requires the Environmental Protection Agency to develop National Emission Standards for Hazardous Pollutants (NESHAP) to reduce overall air toxic emissions. The MPCA measures the amount of many air toxics in the air, focusing on two major categories: volatile organic compounds (VOCs) and metals. The MPCA also collects and reports on emissions of air toxics from major sources in Minnesota.

Greenhouse gases

These are chemicals that contribute to warming of the earth’s atmosphere and climate change. The MPCA tracks and reports emissions for six greenhouse gases: carbon dioxide (CO₂), nitrous oxide (N₂O), methane (CH₄), sulfur hexafluoride (SF₆), and two classes of compounds known collectively as hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs).

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