Carbon dioxide
(CO2) and other greenhouse gases are not
typically considered within this category and are treated separately on Our
World In Data. Disentangling the specic air pollutants—and clearly attributing them to a
specic health or environmental outcome—can be complex since some pollutants
act as pre-cursors to others. For example, SO2 and NOx can react in the Earth’s
atmosphere to form particulate matter (PM) compounds. The sources of each
pollutant vary, however, most are generally linked to fuel combustion and industrial
activities; pollutants are released as by-products of these processes.
Air pollution has a range of negative impacts, including human health, damage to
ecosystems, food crops and the built environment. The World Health Organisation
highlights air pollution as the greatest environmental risk to human health
(note that this is based on current risk- longer-term environmental threats,
such as climate change, may exceed this in the future). It’s estimated to be the
cause of seven million premature deaths every year (4.3 million from ambient
outdoor pollution, and 2.6 from househols.)