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Household air pollution

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Smoke in kitchen

Indoor cooking smoke kills more people each year than malaria. - Practical Action: June, 2006

The World Health Organization reports that in 23 countries 10% of deaths are due to just two environmental risk factors: unsafe water, including poor sanitation and hygiene; and indoor air pollution due to solid fuel use for cooking.[1]

Women and children the world over are exposed daily to a quiet killer: indoor smoke. The World Health Organization states that “indoor air pollution from solid fuel use is responsible for more than 1.6 million annual deaths and 2.7% of the global burden of disease…This makes this risk factor the second biggest environmental contributor to ill health, behind unsafe water and sanitation. Dependence on polluting solid fuels to meet basic energy needs represents one of the biggest threats to children’s health. Acute lower respiratory infections, in particular pneumonia, continue to be the biggest killer of young children and cause more than 2 million annual deaths. This toll almost exclusively falls on children in developing countries.”3 Scarce fuel also means unsafe drinking water is not heated to control water-borne diseases, and slow-cooking nutritious foods such as beans are dropped from family diets. In Kenya, water and smoke related diseases are among the top five major causes of mortality in children under age five years. According to PSI, current estimates show that the country has an annual incidence of between 3.5 and 4.6 severe diarrhea episodes per child.4 Poor nutrition, smoke and unsafe drinking water are also a health threat for people with AIDS.


Map of world deaths attributed to indoor air pollution from using solid fuels.
Indoor Air Polution map-deaths

Only recently has the magnitude of this issue come to the forefront of international concern. Two recent publications―a 2004 briefing by the Intermediate Technology Development Group (ITDG) titled "Smoke: the killer in the kitchen," and the Spring 2003 magazine Public Health from the School of Public Health at the University of California, Berkeley―begin to quantify the negative health effects of exposure to indoor smoke on people in the developing world, especially women and children. The following article is based on the findings in these reports.

Approximately 2.4 billion people―over one-third of all humanity and two-thirds of the developing world―cook over biomass-fueled fires. Common biomass fuels include wood, charcoal, dung and crop residues. And though the percentage of the population that cooks with these fuels is expected to go down over time, the total numbers are expected to rise by as many as 200 million people over the next quarter century. Not only is this environmentally unsustainable at the global level, but the health ramifications are devastating at the community and family levels.

According to the Berkeley report, indoor smoke poses serious health threats. "In homes without ventilation, exposures to particulate matter, along with carbon monoxide, formaldehyde, benzene, nitrogen dioxide, and other gases, can reach 1000 µg/m3 over a 24-hour period―more than 20 times higher than standards set by the U.S. Environmental Protection Agency." Exposure to these pollutants can lead to a number of serious illnesses, including acute lower respiratory infection (ALRI), chronic obstructive pulmonary disease (COPD) and pulmonary tuberculosis. Evidence is mounting that other illnesses, such as lung cancer, asthma and cataracts, as well as low infant birth weight, may also be caused or exacerbated by indoor smoke.

Solar Oven Society - Cooking Air Pollution chart 3-11

Indoor air pollution is the fourth-leading cause of premature death in the developing world. According to the ITDG briefing, women typically spend "three to seven hours per day by the fire, exposed to smoke, often with young children nearby." The briefing summarizes, as follows, the combined effect of these smoke-related illnesses on the population as a whole: "Indoor air pollution from the burning of solid fuels kills over 1.6 million people, predominately women and children, each year. This is more than three people per minute. It is a death toll almost as great a that caused by unsafe water and sanitation, and greater than that caused by malaria." Women, as the briefing points out, are two to four times more likely to suffer COPD when exposed to indoor smoke pollution. Some studies suggest that women who cook over indoor wood fires are 2.5 times more likely to have active tuberculosis.

The ITDG briefing goes on to quantify the effect of indoor smoke on children. "Smoke in the home is one of the world's leading child killers, claiming nearly one million lives each year." In fact, according to the Berkeley report, ALRIs such as pneumonia and bronchitis are the leading cause of death among children in developing countries. Children exposed to indoor smoke are two to three times more likely to contract an ALRI. Children under the age of five account for over 50% of all indoor-smoke related deaths. According to ITDG, the physiology of children makes them "absorb pollutants more readily than adults and also retain them in their system for longer."

So, what can be done about this severe global health issue? People can't very well stop cooking, given that almost all staple foods need to be cooked before they can be eaten. As Dr. E. Bates put it, "If people do not have fuel for lighting, they must sit in the dark; if they do not have fuel for cooking, quite simply, they starve." Suggested solutions include better ventilation for existing cooking devices and the use of cleaner-burning fuels. High costs and limited access greatly reduce the chance that cleaner-burning fuels will be adopted by those most affected. Better ventilation will undoubtedly be incorporated when feasible, but the burning of biomass still negatively affects the environment in numerous ways.

Solar cookers are the only competitively priced, smoke-free solution. Indoor smoke pollution disproportionately affects people living in regions that are conducive to solar cooking: India, China and sub-Saharan African, where the highest proportion of people cook with biomass fuels. The solar cooking community must take action to insure that public health officials are aware of the boon solar cookers are to the health of our women and children.

Extracts From an Interview With Dr. Kirk R. Smith

Kirk R. Smith is among the world’s leading authorities on the problem of indoor air pollution (IAP). A professor of global environmental health at the University of California, Berkeley, Smith has been researching the problem since 1981.

In 2007, the World Health Organization found that IAP was killing about 400,000 people in India every year, most of them women and children. The agency found that pollution levels in some kitchens in rural India were some 20 times higher than recommended and that the pollution was several times as bad as that found in New Delhi. Globally, more than 1.6 million people per year die premature deaths due to IAP caused by burning biomass – wood, dung, roots, straw, and coal in households.

IAP is receiving more attention than it used to. It’s being ranked up there with poor water and sanitation as an environmental risk factor…

Since 2002, we’ve come to understand even more about how household combustion contributes to climate change. And one of the more interesting and important pollutants now is realized to be black carbon — small soot particles which are extremely warming in the atmosphere and also contribute to the melting of glaciers when deposited on them. About one-third of human-caused black carbon emissions in the world are from poor household combustion. So you can’t have a black carbon program without considering combustion in households.

[Source: 7/23/09]


  • December 2012: New study estimates 4 million deaths globally from household cooking smoke each year - The recently released "Global Burden of Disease 2010", funded by the Gates Foundation and just published in The Lancet, comes to this conclusion, and is double the previous accepted estimate. The study isolated the effects of cooking smoke only. There appears to be a shift from communicable children's diseases to non-communicable disease in adult populations as the major health threat affecting developing countries. The cooking problem is compounded by the fact that achieving a fifty percent reduction in cooking smoke does not correlate to a fifty percent reduction in respiratory disease. Substantial smoke reduction is required to see significant improvement. Read more about the air quality findings from the Global Alliance for Clean Cookstoves press release.
  • September 2011: Around three billion people cook and heat their homes using open fires and leaky stoves burning biomass (wood, animal dung and crop waste) and coal. Nearly two million people die prematurely from illness attributable to indoor air pollution from household solid fuel use. Read more...Indoor air pollution and health - World Health Organization

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Air pollution from Asia reaches US shores00:19

Air pollution from Asia reaches US shores

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