Outdoor air pollution is a leading cause of cancer, according to the World Health Organisation (WHO).
It said the world’s leading experts have concluded there is sufficient evidence that exposure causes lung cancer.
WHO’s International Agency for Research on Cancer (IARC) added there was also an increased risk of bladder cancer.
It said there were 223,000 deaths from lung cancer worldwide in 2010 from air pollution.
Air pollution is already known to increase the risk of heart and respiratory diseases, but it has now been officially linked to cancer deaths.
“The air we breathe has become polluted with a mixture of cancer-causing substances,” said Dr Kurt Straif, head of the IARC monographs section. “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.”
WHO said the main sources of air pollution were traffic, power stations, industrial and agricultural emissions and heating and cooking fumes from the home.
“Our task was to evaluate the air everyone breathes rather than focus on specific air pollutants,” said Dr Dana Loomis, deputy head of the monographs section. “The results from the reviewed studies point in the same direction: the risk of developing lung cancer is significantly increased in people exposed to air pollution.”
The WHO is a Geneva-based agency of the United Nations focused on international public health matters.
“Classifying outdoor air pollution as carcinogenic to humans is an important step,” said IARC director, Dr Christopher Wild. “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.”