The International Agency for Research on Cancer (IARC), a specialized agency of the World Health Organization, has classified outdoor air pollution as carcinogenic to humans (Group 1). Particulate matter, a component of air pollution, was also classified as a Group 1 carcinogen. Both were classified based on an increased risk of lung cancer with increasing levels of exposure. It is estimated that in 2010, air pollution caused 223,000 deaths from lung cancer worldwide.
Air pollution also causes heart disease and other respiratory diseases.