Dust and atmospheric aerosol

摘要

Particulate matter-dust or particles in atmospheric aerosol-existing in the air alone or in combination with other pollutants constitutes serious health hazard and damages to envirionemntal quality. Particulate is a term empolyed to describe dispersed airborne solid and liquid particles larger than single molecules (approx. 0.0002 um in diameter) but smaller than 500 um. Particles in this size range have a lifetime in suspension varying from a few seconds to several months. Particles less than 0.1 um undergo random Brownian motions resulting from collision with individual molecules.