Seven million deaths, or one in eight in 2012, are attributed to exposure to indoor and outdoor air pollution, according to new estimates by the World Health Organization (WHO).

Indoor particulate matter air pollution from the burning of solid fuels for heating and cooking caused 4.3 million deaths in 2012, and outdoor particulate matter air pollution caused an additional 3.7 million deaths globally. Regionally, low- and middle-income countries in Southeast Asia and the Western Pacific saw the highest number of air pollution deaths, with a total of 3.3 and 2.6 million deaths caused by indoor and outdoor particulate matter air pollution, respectively.

Exposure to particulate matter air pollution, which includes major climate forcers such as black carbon soot, is linked to such diseases as ischaemic heart disease, strokes, chronic obstructive pulmonary disease, respiratory infections, and lung cancer.

Black carbon soot, one of four climate pollutants known collectively as short-lived climate pollutants (SLCPs) due to their relatively short atmospheric lifetimes, is the second leading cause of global warming behind CO₂. The other three SLCPs are methane, tropospheric ozone, and hydrofluorocarbons, according to WHO.