Particulates

Particulates or Particulate Matter (PM) are tiny pieces of solid or liquid matter associated with the Earth's atmosphere. They are suspended in the atmosphere as atmospheric aerosol, a term which refers to the particulate/air mixture, as opposed to the particulates alone. Sources of particulate matter can be natural or anthropogenic. They have impacts on climate and precipitation that adversely affect human health, in ways additional to direct inhalation.

Sources and Composition

Particulates can be derived from various sources both natural and anthropogenic. Natural sources include volcanoes, dust storms, forest and grassland fires, living vegetation, and sea spray. Human activities, such as the burning of fossil fuels and the alteration of natural surface cover, also generate significant amounts of particulates. Fuel burning in stationary sources, including residential wood burning, power plants, and industrial processes, as well as mobile sources such as automobiles, are among the major anthropogenic sources of particulates.

Health and Environmental Impact

Exposure to particulate matter can cause a number of health problems. For instance, it can lead to respiratory and cardiovascular issues, premature death, allergic reactions and other health problems. Particulates in the atmosphere also have an effect on the Earth's climate. Depending on their albedo (reflectivity), they can either cool the surface of the planet by reflecting sunlight back into space, or warm it by absorbing and re-radiating sunlight as heat.

Measurement and Regulation

The size of the particles is a main determinant of where in the respiratory tract the particles will come to rest when inhaled. Because of this, regulatory agencies such as the Environmental Protection Agency (EPA) in the United States have established standards and guidelines for PM measurements and emissions.

See Also

• Air pollution
• Smog
• Dust
• Aerosol

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