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Tribal-FERST Issue Profile: PM 2.5 (Fine Particulate Matter)

Fine Particulate Matter (known as PM2.5) is a mixture of particles and liquid droplets found in the air. Some particles, such as dust, dirt, soot or smoke, are large or dark enough to be seen with the naked eye while others are so small they can only be detected using an electron microscope. PM2.5 is generally 2.5 micrometers and smaller. This fine PM is the main cause of reduced visibility (haze) in parts of the U.S. More importantly, fine PM is small enough to be inhaled and this can cause serious health problems.

Some PM comes from sources, such as construction sites, unpaved roads, fields, smokestacks or fires. However, most PM forms in the atmosphere from complex chemical reactions among pollutants such as sulfur dioxide and nitrogen oxides. Typical sources of these chemicals include power plants and automobiles.

EPA regulates inhalable particles, which includes fine PM. Particles of sand and large dust, which are larger than 10 micrometers and not inhalable, are not regulated by EPA. EPA’s national and regional rules seek to reduce emissions of the pollutants that form fine PM and help state and local governments meet National Ambient Air Quality Standards (NAAQS).

To learn more about fine PM, its sources, and how to minimize health risks, see the resources below.

General Information


Environmental Concentrations, Human Exposures, and Health Risks

Interested in learning more about a specific location? Type an address, city or ZIP code into the box on the right side of the map below. Click on the map to see a pop-up with information about ambient concentration, exposure concentration and cancer risk for the chosen location(s). Navigate to the next feature by clicking the small arrow(s) on the top right side of the pop-up.

Exposure and Risk Reduction Options

Strategies Implemented By Other Communities

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