Air pollution causes lung cancer, warns World Health Organisation Pollution in the air we breathe should be considered carcinogenic, the World Health Organisation (WHO) has warned. The International Agency for Research on Cancer (IARC), a department within WHO, has classified outdoor pollution as a leading environmental cause of cancer death, and listed common sources of these pollutants as transport, power generation, industrial and agricultural emissions, and heating and cooking in residential buildings. IARC said the evidence made clear these forms of pollution can cause lung cancer. It has now classified air pollution in the same category as tobacco smoke, UV radiation and plutonium. In 2010, 223,000 people worldwide died of lung cancer triggered by air pollution, according to the IARC. More than half of these deaths were thought to have occurred in China and East Asian countries associated with rapid industrialisation. Dr Kurt Straif, head of the IARC monographs section, said: "The air we breathe has become polluted with a mixture of cancer-causing substances. Particulate matter, a major component of outdoor air pollution, was evaluated separately and was also classified as carcinogenic to humans. Researchers said that although the composition of air pollution and levels of exposure can vary dramatically between areas, their findings apply to all regions of the world. In a statement, IARC director Dr Christopher Wild said: "Classifying outdoor air pollution as carcinogenic to humans is an important step.