Problem Identification

Air pollution is a problem as old as history itself. Air pollution can be defined broadly as the introduction of chemicals, particulate matter, or biological materials into the atmosphere that cause harm or discomfort to humans or other living organisms, or cause damage to the natural environment or built environment. Air pollution can be classified into anthropogenic and non-anthropogenic origin. The latter includes natural events such as wildfires, volcanic activity, and dust/sandstorms. This source of air pollution is not considered in this chapter as it is largely context-specific, and since the year 1900 is likely to be relatively unimportant compared with air pollution of anthropogenic origin.

Anthropogenic, or man-made, air pollution can be traced back to when humanity discovered how to make fire. While air pollution in those days was insignificant compared to the present time, burning biomass in enclosed spaces for space heating or for cooking purposes would have exposed humans to risk of respiratory diseases and injuries. As human populations became settled and increasingly burned biomass and fossil fuels (such as coal) indoors, the exposure to air pollution and its negative consequences rose significantly. Annex 1 shows the percentage of populations in developing countries burning solid fuels indoors, ranging from 16% of households in Latin America and the Caribbean and Central and Eastern European regions, to 74% in Southeast Asian and Western Pacific regions and 77% in Africa (Rehfuess et al. 2006).