The effects of air pollutants on human health are directly related to exposure to such pollutants. This makes it possible to determine the short-term and long-term effects of exposure to airborne pollutants.

Air (Latin: aer) is a homogeneous mixture of gases (volatile elements and chemical compounds) and atmospheric areolae (microscopic solid particles and droplets of liquid suspended in a gaseous phase) forming the gaseous (entrusted) layer of the globe, whose chemical composition is balanced by the circulation of gases in the troposphere. However, the term ‘air’ is also sometimes used to refer to all spheres of the earth’s atmosphere (with different chemical compositions and physical properties).