Around seven million people across the world died as a result of air pollution exposure in 2012, according to a report of World Health Organization(WHO) released on Tuesday.

The report said the seven million deaths, one in eight of total global deaths confirmed that air pollution is now the world's largest single environmental health risk, and reducing air pollution could save millions of lives.

In particular, the new data reveal a stronger link between both indoor and outdoor air pollution exposure and cardiovascular diseases, such as strokes and ischemic heart disease, as well as between air pollution and cancer.

The report said that low- and middle-income countries in 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.

According to the report, for the deaths related to outdoor pollution, 40 percent were heart disease, and 40 percent were stroke, 11 percent were chronic obstructive pulmonary disease(COPD), six percent were lung cancer and three percent were acute lower respiratory infections in children.

While the proportion of the same diseases caused by indoor pollution were 26 percent, 34 percent, 22 percent, six percent and 12 percent, respectively.

After analyzing the risk factors and taking into account revisions in methodology, WHO estimates indoor air pollution was linked to 4.3 million deaths in 2012 in households cooking over coal, wood and biomass stoves.

In the case of outdoor air pollution, WHO estimates there were 3.7 million deaths in 2012 from urban and rural sources worldwide.

Many people are exposed to both indoor and outdoor air pollution. Due to this overlap, mortality attributed to the two sources cannot simply be added together, hence the total estimate of around 7 million deaths in 2012.

"Cleaning up the air we breathe prevents noncommunicable diseases as well as reduces disease risks among women and vulnerable groups, including children and the elderly,"said 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," she added.

"The risks from air pollution are now far greater than previously thought or understood, particularly for heart disease and strokes," said Dr Maria Neira, director of WHO's Department for Public Health, Environmental and Social Determinants of Health.

"Few risks have a greater impact on global health today than air pollution; the evidence signals the need for concerted action to clean up the air we all breathe," she said.

Later this year, WHO will release indoor air quality guidelines on household fuel combustion, as well as country data on outdoor and indoor air pollution exposures and related mortality, plus an update of air quality measurements in 1,600 cities from all regions of the world.