A man looks out over the smoke filled Singapore skyline on in Singapore. The Pollutant Standards Index (PSI) rose to the highest level on record reaching 371 / Getty Images

WHO cancer agency has classified air pollutants as carcinogenic, alongside tobacco and UV radiation

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.

”We now know that outdoor air pollution is not only a major risk to health in general, but also a leading environmental cause of cancer deaths."

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.

“There are effective ways to reduce air pollution and, given the scale of the exposure affecting people worldwide, this report should send a strong signal to the international community to take action without further delay.”