LONDON: Air pollution has emerged as the world's single largest environmental health risk, having caused seven million deaths in 2012 — 80% of which were from heart attacks and stroke.

The WHO announced on Tuesday that 1 in 8 global deaths were linked with air pollution. It recently categorized outdoor air pollution — caused by car exhausts, power stations, emissions from agriculture and industry as well as heating in people's homes — as a Group 1 carcinogenic, a cancer causing agent in the same category as tobacco smoke, UV radiation and plutonium. World Health Organization's International Agency for Research on Cancer (IARC) said there was "sufficient evidence of carcinogenicity in humans".

Six per cent of these deaths were due to lung cancer caused by both outdoor and indoor air pollution. This is the first time that WHO has directly suggested a link between air pollution and heart disease, respiratory problems and cancer. This finding more than doubles previous estimates of deaths caused by air pollution.

Regionally, low- and middle-income countries in the WHO South-East Asia and Western Pacific Regions had the largest air pollution-related burden in 2012, with a total of 3.3 million deaths linked to indoor air pollution and 2.6 million deaths related to outdoor air pollution. "Cleaning up the air we breathe prevents non communicable diseases as well as reduces disease risks among women and vulnerable groups, including children and the elderly," says Dr Flavia Bustreo, WHO assistant director-general family, women and children's health. "Poor women and children pay a heavy price from indoor air pollution since they spend more time at home breathing in smoke and soot from leaky coal and wood cook stoves." After analysing the risk factors, WHO estimated that indoor air pollution was linked to 4.3 million deaths in 2012 in households cooking over coal, wood and biomass stoves. The new estimate is explained by better information about pollution exposures among the estimated 2.9 billion people living in homes using wood, coal or dung as their primary cooking fuel, as well as evidence about air pollution's role in the development of cardiovascular and respiratory diseases, and cancers.