World Health Organisation names air pollution as the main cause of lung cancer In 2010, air pollution caused the deaths of 223,000 lung cancer patients, according to the World Health Organisation There is also 'convincing evidence' it increases risk of bladder cancer Main sources of outdoor air pollution are transport, power generation, industrial and agricultural emissions In residential buildings, heating and cooking are to blame The air we breathe is laced with cancer-causing substances and is being officially classified as carcinogenic to humans, the World Health Organisation has said. The International Agency for Research on Cancer (IARC) said that in 2010, 223,000 deaths from lung cancer worldwide resulted from air pollution. The agency also said that there is convincing evidence it increases the risk of bladder cancer. Motorists travel through haze in Pekanbaru, Indonesia. Air pollution has been named as the main cause of lung cancer by the World Health Organisation It listed the main sources of outdoor air pollution as transport, power generation, industrial and agricultural emissions, and heating and cooking in residential buildings. Some air pollutants also have natural sources, it added. Air pollution is already known to increase risks for a wide range of diseases, such as respiratory and heart diseases. Depending on the level of exposure in different parts of the world, the risk was found to be similar to that of breathing in second-hand tobacco smoke, Kurt Straif, head of the agency's section that ranks carcinogens, told reporters in Geneva. In a statement, deputy head of the WHO cancer agency, Dana Loomis, said: 'Our task was to evaluate the air everyone breathes rather than focus on specific air pollutants. 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. Air pollution, mostly caused by transport, power generation, industrial or agricultural emissions and residential heating and cooking, is already known to raise risks for a wide range of illnesses including respiratory and heart diseases. Research suggests that exposure levels have risen significantly in some parts of the world, particularly countries with large populations going through rapid industrialisation, such as China. Air pollution has also been linked to bladder cancer by the World Health Organisation IARC reviewed thousands of studies on air pollution tracking populations over decades and other research such as those in which mice exposed to polluted air experienced increased numbers of lung tumours. In a statement released after reviewing the literature, the Lyon-based agency said both air pollution and particulate matter - a major component of it - would now be classified among its Group 1 human carcinogens. That ranks them alongside more than 100 other known cancer-causing substances in IARC's Group 1, including asbestos, plutonium, silica dust, ultraviolet radiation and tobacco smoke. Dr. Christopher Wild, director of IARC, told a news briefing in Geneva that the work's aim is to be as comprehensive as possible. He said: 'Often we're looking at two, three or four decades once an exposure is introduced before there is sufficient impact on the burden of cancer in the population to be able to study this type of question.'