Risk factors for respiratory diseases: indoor air pollution

Indoor environments contribute significantly to total human exposure to air pollutants. Overall, people spend most time indoors. Pollutants remain in the air longer inside than outside. For some pollutants, indoor exposure probably dominates the global human exposure. About 85% of particulate matter (PM) pollution exposures are estimated to occur indoors. Some pollutants may be two to fivefold more concentrated inside than outside the buildings; furthermore, indoor pollutants may have an important biological impact even at low concentrations over long exposure periods. Indoor air pollution (IAP) represents a substantial risk for human health, particularly for children (their defense mechanisms are still evolving, and they inhale a higher volume of air per body weight than adults), elderly people, subjects with cardiorespiratory diseases, at higher risk for specific exposures, or socioeconomically deprived. The largest health impacts occur among the poorest and most vulnerable populations, such as those living in low-middle income countries (LMIC), especially in the least developed countries (LDC), where people suffer conditions of extreme poverty, conflicts and wars, lack of political and social stability, and often authoritarian forms of government. Indoor exposure mainly occurs at home and in workplaces/schools, but also in day care centers, social recreation settings, or microenvironments, such as cars, buses, trains, subways, airplanes.