Clean air sets our state apart. To lead in this arena and ensure that every person in Minnesota has healthy air to breathe, the MPCA studies, monitors, and regulates air pollutants, primarily in three categories: criteria pollutants, air toxics, and greenhouse gases.

Criteria pollutants

The Clean Air Act requires the U.S. Environmental Protection Agency (EPA) to set national ambient air quality standards for six common air pollutants, called “criteria pollutants":

  • Ground-level ozone
  • Particulate matter
  • Lead
  • Nitrogen dioxide
  • Carbon monoxide
  • Sulfur dioxide

Volatile organic compounds (VOCs) that do not have standards are also monitored, tracked, and controlled to help reduce ozone concentrations in our air.

All states are required to meet these standards or develop plans to come into compliance. Minnesota is currently meeting these national standards.

Air toxics

Hazardous air pollutants are a group of 188 specific pollutants that cause or may cause cancer or other serious health effects or adverse environmental and ecological effects. They are specified in the Clean Air Act amendments. There are not state or federal ambient air quality standards for individual air toxics, but the Clean Air Act requires the EPA to develop National Emission Standards for Hazardous Pollutants to reduce overall air toxic emissions.

The MPCA collects data on emissions of air toxics from major sources in Minnesota every three years and reports findings in the Minnesota Air Toxics Emissions Inventory. The agency monitors for air toxics at a few sites in the Twin Cities and Duluth and uses emissions and modeling data to estimate the concentrations of air toxics in other areas of the state. According to monitoring and modeling data, three types of air toxics are particularly important in the state.

  • Volatile organic compounds — VOCs are emitted from a variety of sources, including paint, solvents, adhesives, gasoline, cleaning products, and fuel when burned. Formaldehyde is a VOC frequently measured above health benchmark levels in urban areas.
  • Metals — Metals are emitted from industrial processes and fossil-fuel combustion. Levels of chromium, arsenic, and nickel are sometimes above health benchmarks in areas with significant particle pollution.
  • Polycyclic aromatic hydrocarbons (PAHs) — PAHs are a class of more than 100 chemicals that come from sources such as tobacco smoke, wood smoke, vehicles, and asphalt roads.

Greenhouse gases

These chemicals contribute to warming of the earth’s atmosphere and climate change. The MPCA reports emissions for six greenhouse gases:

  • Carbon dioxide
  • Nitrous oxide
  • Methane
  • Sulfur hexafluoride
  • Hydrofluorocarbons
  • Perfluorocarbons

New source review pollutants

The regulated new source review pollutants include the criteria pollutants, greenhouse gases, sulfuric acid mist, hydrogen sulfide, and more. Learn more:

Choose a pollutant below to learn where it comes from and its effects on human health and the environment, and monitoring and regulation information.

Carbon monoxide (CO) is a product of the incomplete combustion of carbon-based fuels — including gasoline, diesel fuel, crude oil, and wood — and other natural and synthetic products.

Fine particles are dust, soot, smoke, liquid droplets, and other particles in the air that range in size from less than 0.1 microns in diameter to about 10 microns, They are small enough to be breathed in and even enter the bloodstream.

Heavy metals are an ill-defined group of inorganic chemical hazards including lead, chromium, arsenic, and cadmium.

Mercury is a naturally occurring element that is toxic to humans and animals. At room temperature, mercury is a silvery, liquid metal, but it can also evaporate and become airborne. Mercury does not break down into less toxic substances, like some pollutants.

Nitrogen dioxide (NO2) is one of a group of highly reactive gases known as nitrogen oxides.

Ground-level ozone is a secondary pollutant formed through chemical reactions between nitrogen oxides and volatile organic compounds, and a criteria pollutant regulated under the federal Clean Air Act.

Per- and polyfluoroalkyl substances (PFAS) are a group of over 5,000 man-made chemicals that do not break down over time.

Polycyclic aromatic hydrocarbons (PAHs) are a class of more than 100 chemicals that occur naturally in coal, crude oil, and gasoline, and are also present in products made from fossil fuels, such as coal-tar pitch, creosote, and asphalt.

Sulfur dioxide (SO2), a bad-smelling toxic gas, is part of a larger group of chemicals called sulfur oxides. These gases, especially SO2, are emitted by the burning of fossil fuels or other materials that contain sulfur.

Volatile organic compounds (VOCs) are a group of chemicals that can both vaporize into air and dissolve in water. VOCs are in thousands of every-day-use products, including paint, varnish, wax, and various cleaning, degreasing, and cosmetic products.