Air pollution is considered as carcinogen, a substance that causes cancer. This was declared by the International Agency for Research on Cancer on Thursday. The conclusion was drawn after a discussion by an expert team organized by IARC, the cancer agency of the World Health Organization, which is based in Lyon, France.

Kurt Straif, head of the IARC department that evaluates cancer-causing substances, said, "We consider this to be the most important environmental carcinogen, more so than passive smoking".

IARC had earlier considered that some of the components in air pollution such as diesel fumes to be carcinogens. However, this is the very first time it has held air pollution responsible for cancer.

The risk to the person is low. Straif told that the main causes of pollution are very common. It includes transportation, power plants, and industrial and agricultural emissions. Air pollution is an intricate mixture of gases and particulate matter. IARC said one of its main hazards is the fine particles, which can be deposited deep in the lungs of a person.

In 2010, IARC revealed that more than 220,000 lung cancer deaths all over the world were caused due to air pollution. The agency also told that chances of lung cancer are slightly higher than the risk of bladder cancer.