Air pollution exposure is the amount of airborne fine particulate matter that a population is subjected to.

Air pollution is the presence of contaminant or pollutant substances in the air that do not disperse properly and that interfere with human health or welfare, or produce other harmful environmental effects.

Fine particulate matter (PM2.5) are finely divided solids or liquids with a diameter of less than 2.5 µm that may be dispersed through the air from combustion processes, industrial activities or natural sources. When inhaled, exposure has been shown to cause serious health problems including both respiratory and cardiovascular disease. They considerably increase the risk of heart disease and stroke, having its most severe effects on children and elderly people.

This indicator is measured as a percentage of population exposure to more than 10 micrograms/m³ and is expressed as annual averages.