According to a World Health Organization report released today, around 1 in 8 of total global deaths - 7 million deaths annually - are as a result of exposure to air pollution.

The new data challenges previous information on air pollution. The figure of 7 million more than doubles the previous estimate of annual air pollution-caused deaths, making air pollution now the world's largest single environmental health risk.

"The risks from air pollution are now far greater than previously thought or understood, particularly for heart disease and strokes," says Dr. Maria Neira, director of the World Heath Organization's (WHO) 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 adds.

Air pollution's contribution to the development of respiratory diseases is well known, but WHO's findings also emphasize a more robust connection than has previously been reported between air pollution and cardiovascular disease and cancer.

New data 'more accurate' than previous estimates

WHO claim that the new figures are more accurate than previous estimates, because not only is more now known about the diseases influenced by air pollution, but also improved technology allows for better measurements of human exposure to air pollution.

This new approach combined satellite data, ground-level monitoring measurements, data on pollution emissions and modeling of how pollution drifts in the air.

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"Excessive air pollution is often a by-product of unsustainable policies in sectors such as transport, energy, waste management and industry," say WHO experts.

The study found that the countries with the most air pollution were the low- and middle-income countries in the southeast Asia and western Pacific regions. A total of 3.3 million deaths were linked to indoor air pollution in these countries, and 2.6 million deaths were related to outdoor air pollution.

During 2012 - the year in which the data was collected - WHO estimate that 4.3 million global deaths were linked to cooking over coal, wood and biomass stoves. They also estimated that 3.7 million global deaths occurred as a result of outdoor air pollution.

There is an overlap of indoor and outdoor pollution, with some people being exposed to both types of pollution. So rather than add the two mortality figures together, WHO estimated that 7 million deaths in total were as a result of air pollution.

"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," says Dr. Flavia Bustreo, WHO assistant director-general of Family, Women and Children's Health.

"Poor women and children pay a heavy price from indoor air pollution," Dr. Bustreo continues, "since they spend more time at home breathing in smoke and soot from leaky coal and wood cook stoves."

Breakdown of air pollution-related deaths by disease

The WHO assessment also included a a breakdown of deaths attributed to air pollution-influenced diseases, the key points of which are reproduced below.

Outdoor air pollution-caused deaths:

  • Ischemic heart disease - 40%
  • Stroke - 40%
  • Chronic obstructive pulmonary disease (COPD) - 11%
  • Lung cancer - 6%
  • Acute lower respiratory infections in children - 3%.

Indoor air pollution-caused deaths:

  • Stroke - 34%
  • Ischemic heart disease - 26%
  • COPD - 22%
  • Acute lower respiratory infections in children - 12%
  • Lung cancer - 6%.

Dr. Carlos Dora, WHO coordinator for Public Health, Environmental and Social Determinants of Health, hopes that the new evidence presented by the report will contribute to policy improvements that may reduce future air pollution-related deaths:

"Excessive air pollution is often a by-product of unsustainable policies in sectors such as transport, energy, waste management and industry. In most cases, healthier strategies will also be more economical in the long term due to health care cost savings as well as climate gains. WHO and health sectors have a unique role in translating scientific evidence on air pollution into policies that can deliver impact and improvements that will save lives."

In 2013, Medical News Today reported on a study in The Lancet that demonstrated air pollution can kill at levels way below the European Union's current air pollution guidelines, and which urged a move to WHO's more stringent guidelines.