It does not include particulate matter from other common sources, such as vehicle exhaust or smokestacks. Fugitive dust particles are mainly minerals common to soil, including silicon oxides, aluminium, calcium, and iron. About half of fugitive dust particles are larger than 10 microns in diameter and settle more quickly than the smaller particles.[1] 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).[2]