National Geographic News
A photo of a woman cooking food in her shanty in Mumbai.

A woman cooks food in her shanty in Mumbai, India.


Susan Brink

for National Geographic

Published March 25, 2014

Seven million people die each year because of exposure to air pollution. That's one in eight deaths across the globe, making air pollution the single greatest environmental health risk on Earth. The estimate was reported this week by the World Health Organization; based on 2012 numbers, it is double the WHO's previous 2008 estimate.

What's more shocking is that the air pollution is often in the victim's own home. More than half of those deaths are caused by indoor pollutants, which in the developing world largely come from indoor cooking stove fuels like wood, coal, and cow dung.

Since the 1970s, Kirk Smith, professor of global environmental health at the University of California at Berkeley, has studied the effects of indoor cooking using solid fuels like wood, coal, and cow dung. He told the WHO, "Having an open fire in your kitchen is like burning 400 cigarettes an hour."

Carlos Dora, coordinator for the WHO Interventions for Healthy Environments unit, prefers to put it more scientifically. "The home with a dirty cookstove using coal can reach 2,000 or 3,000 micrograms per cubic meter of particles," he says. That's 200 to 300 times the WHO's average daily standard for maximum concentration of the fine particles of air pollution—about 25 to 100 times smaller than a human hair—that can settle deeply in the lungs.

Breathing those microscopic dirty particles causes more than lung cancer, which is responsible for only 6 percent of the seven million premature deaths caused by air pollution. The vast majority of deaths—69 percent—are due to heart disease or stroke.

Evidence of the cardiovascular harm from air pollution has increased since the WHO's last report. That's one reason the estimated number of deaths has risen so dramatically. The other reason is that the organization has developed better ways to measure pollution outside of urban areas.

"There are more epidemiological studies showing a clear connection between air pollution and heart disease and stroke. The evidence now is robust," says Dora. "And we have better models of how pollution travels and more monitoring stations in rural areas."

Almost three million people around the world use dirty solid fuels to do their cooking. Women and children, whose days often center around gathering fuel and cooking, are more exposed to pollutants than men. Yet death rates attributed to air pollution are higher, at 49 percent, among men than among women, at 42 percent. Men in general have more risk factors—like smoking or a high-fat diet—than women do, says Dora. "Any one risk factor has a higher impact on people who already have a number of other risk factors."

The report measured the global impact of pollution by region, not individual countries. The western Pacific, Southeast Asian, and African regions accounted for almost six million premature deaths. But there have been fewer than 400,000 premature deaths from air pollution in high-income countries and regions of Europe and the Americas, where laws and regulations have decreased outdoor air pollution, smoking indoors has become culturally unacceptable, and almost no one cooks with coal or cow dung.

Kiran Padale
Kiran Padale

I have been working in rural development sector for past 7 years and it realized that NGOs do made attempts to introduce improved stoves which reduce the smoke and increased fuel efficiency !! However, one needs to keep in mind that cow dung is easily available in rural areas and has been traditionally use as major source for cooking food. Practically, the alternate solutions is difficult but possible.



휘배 김
휘배 김

Unbelievable report! I can't imagine that 7million people die each year because of indoor pollution.

Andrew Booth
Andrew Booth

The last but one paragraph quotes "Almost three million people around the world use dirty solid fuels to do their cooking". Is that figure correct? I would have thought it was considerably more than three million people, especially as the numbers of deaths are the basis of the article.

Sharalyn Pliler
Sharalyn Pliler

Does this also apply to those who burn wood for heating?


c'est vrai qu'après une heure dans une cuisine ou la chaleur du four, les vapeurs émises par les marmites la fournaise due à la cuisson de la galette; j'ai automatiquement la migraine, et je cuisine au gaz naturel. que dire de ces pauvres malheureux qui en sont encore au charbons de bois et bouses de vaches!! mais même les bonbonnes de gaz " butane"  peuvent causer la mort comme explosion, fuite de gaz... y a pas que la crise cardiaque qui nous guette  au tournant dirait-on !!!! ALLAH yestour.     

Alberto Lopez Jr
Alberto Lopez Jr

@Sharalyn Pliler  Not if burned in a fireplace. The pollutants would escape, not being trapped indoors thus causing all the problems described above. Make a fire in the middle of the room and there's the problem. this article is about indoor pollutants. Fireplaces were created to send those pollutants outdoors

Gerald Sobel
Gerald Sobel

@Alberto Lopez Jr @Sharalyn Pliler I have neighbors who use a fireplace to heat, here, in Santa Monica, CA, a locale otherwise highly regulated with respect to air-borne pollution. The problem is, the smoke form their chimney blows into my apartment, even with my window closed, and causes a burning stinging sensation in my lungs. This is bad! Apparently, there are NO REGULATIONS ABOUT BURNING WOOD HERE despite the pollution and odor it causes. Stupid huh? But that's politics for you.


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