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Concept
Fugitive dust
Résumé
Fugitive dust is an environmental air quality term for very small particles suspended in the air, primarily mineral dust that is sourced from the soil of Earth's pedosphere. A significant volume of fugitive dust that is visible from a distance is known as a dust cloud, and a large dust cloud driven by a gust front is known as a dust storm.
Fugitive dust particles are mainly minerals common to soil, including silicon oxides, aluminium oxides, calcium carbonates and iron oxides. About half of fugitive dust particles are larger than 10 microns in diameter and settle more quickly than the smaller particles. It does not include particulate matter from other common artificial sources such as vehicle exhaust, burn piles or smokestacks. The term is used to denote that the dust "escapes" into the atmosphere rather than being exhausted in a "confined flow stream" from a "ducted emitter" (an exhaust pipe or chimney).
The U.S. Environmental Protection Agency estimated that fugitive dust was responsible for 92% of the PM-10 emissions in the United States in 1995.
Fugitive dust results from dry conditions where there is insufficient moisture content in the ground to maintain adhesion and hold the soil together. Particulate matter (PM) then enters the atmosphere through the action of wind, vehicular movement, or other activities.
Areas with dryland or desert climates, especially when combined with high winds, have more severe problems of fugitive dust. Dry and disturbed surfaces can release wind-borne fugitive dust for many months before there is sufficient rainfall to coagulate the soil, this includes the dust Bulldust. Large-scale fugitive dust driven by gust fronts creates a dust storm.
Surfaces susceptible to fugitive dust emissions are both natural and man-made. Specific sources include open fields and parking lots, paved and unpaved roads, agricultural fields, construction sites, unenclosed storage piles, and material transfer systems..
Source officielle
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