A report published by The International Agency for Research on Cancer (IARC) announced, for the first time, that air pollution causes lung cancer.
It puts air pollution in the same category as tobacco smoke, UV radiation and plutonium.
Previously only specific components of air pollution, such as diesel exhausts, were implicated in cancers.
Sources of air pollution include car exhausts, power stations and factories – as well as heating in people’s homes.
The World Health Organisation said the classification should act as a strong message to governments to take action.
According to the Deputy Head of International Agency for Research of Cancer (IARC) Dana Loomis, the agency was tasked with evaluating the quality of today’s air.
The group reviewed thousands of studies on air’s composition, and after examining decades worth of data, the IARC announced that both air pollution and “particulate matter” are now Group 1 carcinogens.
He said: “There is a concentration of high pollution through Asia, but also in Africa, which may be surprising. In China and in India, much of what we see is due to coal burning – it’s industry and all the industrial development that’s taking place in those countries.
`“Here in northern Africa of course it’s mostly desert with few people, and the particulate pollution that we see there is from wind-blown desert dust – so it’s quite different in character from the pollution that’s coming from industry.”
The agency said the most recent data suggested 223,000 deaths from lung cancer around the world were caused by air pollution.
More than half of the deaths were thought to be in China and other East Asian countries.