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Particulate Matter (PM 10, PM 2.5 and PM 1.0)

Particulate matter, or PM, is the term for particles found in the air, including dust, dirt, soot, smoke, and liquid droplets. Particles can be suspended in the air for long periods of time. Some particles are large or dark enough to be seen as soot or smoke. Others are so small that individually they can only be detected with an electron microscope. Some particles are directly emitted into the air. They come from a variety of sources such as cars, trucks, buses, factories, construction sites, tilled fields, unpaved roads, stone crushing, and burning of wood. Other particles may be formed in the air from the chemical change of gases. They are indirectly formed when gases from burning fuels react with sunlight and water vapor. These can result from fuel combustion in motor vehicles, at power plants, and in other industrial processes.

Other particles may be formed in the air from the chemical change of gases. They are indirectly formed when gases from burning fuels react with sunlight and water vapor. These can result from fuel combustion in motor vehicles, at power plants, and in other industrial processes.

 

Chief Causes for Concern

PM. . .

is associated with increased hospital admissions and emergency room visits for people with heart and lung disease.

is associated with work and school absences.

is the major source of haze that reduces visibility in many parts of the United States, including our National Parks.

settles on soil and water and harms the environment by changing the nutrient and chemical balance.

causes erosion and staining of structures including culturally important objects such as monuments and statues.

Health problems for sensitive people can get worse if they are exposed to high levels of PM for several days in a row.