Air pollution leading cause of cancer, World Health Organisation warns

The World Health Organisation has classified outdoor air pollution as a leading cause of cancer.

"The air we breathe has become polluted with a mixture of cancer-causing substances. We consider this to be the most important environmental carcinogen, more so than passive smoking," said Kurt Straif, head of the WHO's International Agency for Research on Cancer.

The agency evaluates cancer-causing substances.

Previously, air pollution had been found to boost the chances of heart and respiratory diseases and the agency had deemed some of the components in air pollution, such as diesel fumes, to be carcinogens.

But this is the first time it has classified air pollution in its entirety as causing cancer.

Straif said the risk to the individual was low, but the main sources of pollution were widespread, including transport, power plants and industrial and agricultural emissions. Research suggests that in recent years, exposure levels have risen significantly in some parts of the world, particularly countries with large populations going through rapid industrialisation such as China.

The most recent data, from 2010, showed that 223,000 lung cancer deaths worldwide were the result of air pollution.