Last edited: 22 March 2022
Women and children the world over, are exposed daily to a quiet killer: household smoke. The World Health Organization (WHO) reports that in 23 countries, 10% of deaths are due to just two environmental risk factors: unsafe water, including poor sanitation and hygiene; and household air pollution due to solid fuel use for cooking. A WHO report from June 2015 states that "seven million deaths every year are attributable to air pollution. This makes it one of the deadliest health risk factors globally, comparable to tobacco smoking, and the greatest cause of death in some countries.
Globally, 88% of the world’s population breathes air that does not meet WHO’s air quality guidelines". While much of this pollution comes from transportation and power generation emissions, household sources are a significant contributor to global air pollution. For example, a December 2016 publication from the Global Alliance for Clean Cookstoves reports that researchers in India found that 30% of outdoor particulate matter pollution can be attributed to household emissions. A separate study, conducted in China, found "efforts to reduce household air pollution have been considerably more effective at reducing overall pollution than efforts to regulate emissions from the transportation and power sectors." Although curbing emissions from these sources is a critical step in reducing global air pollution, expanding the use of clean cookstoves can often lead to the most rapid benefits for individuals and their families as clean cookstoves greatly reduce or eliminate the dangerous health impacts of household air pollution. The good news is that the adoption of tier 4 (non-biomass) stoves, which have lowest emissions of all available stoves and includes solar cookers, increased from ~30% in 2013 to almost 50% in 2015.
The World Health Organization has reports "household 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 four million annual deaths. This toll almost exclusively falls on children in developing countries.” Scarce fuel also often 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. Poor nutrition, smoke and unsafe drinking water are also a health threat for people with AIDS.
Only recently has the magnitude of this issue come to the forefront of international concern. Two 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―attempt to quantify the negative health effects of exposure to indoor smoke on people in the developing world, especially women and children.
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, 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.
Household 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. Household 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 in 2009
Kirk R. Smith is among the world’s leading authorities on the problem of household air pollution (HAP). 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 HAP 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 HAP caused by burning biomass – wood, dung, roots, straw, and coal in households. HAP 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: Worldpress.com 7/23/09]
Environmental versus health safety considerations for fuelwood-burning stoves
The team of Rob Balis, Majid Ezzati, and Daniel Kammen have done extensive research into the pollution generated from wood-burning cookstoves in Africa. Daniel Kammen, a professor of public policy at the University of California at Berkeley, reports that their findings show the levels of greenhouse gas emissions (GHG) from charcoal burning and production, are significantly higher than previously believed. He estimates that 250 million people use charcoal for their domestic energy at least once a week, mainly in Africa, parts of Asia, and Brazil. Their findings were first published in the March 2003 issue of Environmental Science and Technology. Read their report at Greenhouse Gas Implications of Household Energy Technology in Kenya The charcoal-fueled stoves do however, produce 75−95% less carbon particulate compared to wood-fueled alternatives. This fact immediately points to a benefit of burning charcoal to reduce the incidence of particulate related respiratory disease. If large scale charcoal production is able to be done in a sustainable fashion, charcoal can be promoted to significantly help reduce respiratory disease. However, often charcoal production is done illegally, using very inefficient techniques, creating additional environmental problems. The use of an efficient, well-maintained wood stove, like the improved combustion stoves variety, will reduce carbon emissions by approximately 50% over open fires. Limiting the air flow, or damping down the air intake of these stoves, will lower the stove temperature and extend cooking times, but will release more carbon particulate. Conversely, the use of charcoal increases the amount of other greenhouse gas emissions released into the atmosphere when compared to using wood or biomass fuels. Possibly 6-13 times as much GHG is released using charcoal fuel compared with bio-mass fuels. According to Kammen, this negative aspect is not significant compared to the respiratory health benefit of cooking with charcoal. The amount of GHG emissions generated by cooking activities is still a very small contributor to the total coming from all other emission sources. Improved combustion wood stoves will continue to be an important component of integrated cooking. Their use will be encouraged, when solar cooking is not possible. With either approach, heat-retention cooking can save time and fuel.
- November 2021: Cooking with polluting fuels is a silent killer - here’s what can be done - World Economic Forum
- May 2021: How is Gas Harming Our Health? What You Need to Know - climatecouncil.au
- September 2019: Clean Cooking: The Forgotten Link in Universal Energy Access - International Policy Digest
- August 2016: Updated report from February 2016; Household air pollution and health from the World Health Organization.
- June 2016: The Lancet Neurology: For the first time, air pollution emerges as a leading risk factor for stroke worldwide - The Lancet
- June 2016: Traditional Charcoal in Africa and Need of African Institutes (ARTIS) - Dieter Seifert
- November 2014: After having announced earlier in 2014 that an estimated seven million people die annually from pollution exposure, the World Health Organization (WHO) has issued benchmarks for achieving healthy air in and around the home. Among its suggestions, WHO recommends avoiding unprocessed coal and kerosene as household fuels. World Health Organization (WHO) Sets Indoor Air Quality Guidelines
- March 2014: The World Health Organization (WHO) estimates that 4.3 million people die annually from household air pollution caused by cooking with biomass and coal. It is the greatest health risk in the world after high blood pressure, tobacco and alcohol, with more people dying from the incremental, ongoing inhalation of smoke from fires they ignite in their own homes than from malaria, tuberculosis and HIV/AIDS combined. Read WHO report summary: Burden of disease from Household Air Pollution for 2012
- December 2012: A 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 household air pollution from household solid fuel use. Read more...Indoor air pollution and health - World Health Organization
Articles in the media
- March 2022: Study: World's vulnerable are being polluted in their own homes as they cook - Medical Press
- June 2020: Clean Cooking: 33 Solutions For One Renewable Energy Problem - CleanTechnica
- December 2018: WHO calls on countries to embrace non-polluting sources of energy - Ghana Web
- May 2018 Household air pollution and health - World Health Organization
- October 2017: How stoves can help solve a global pollution crisis - CBS News MoneyWatch
- June 2016: From cookstoves to forests, UN puts eye on mending global environment - Christian Science Monitor
- May 2016: WHO: Global air pollution is worsening, and poor countries are being hit the hardest - The Washington Post
- May 2016: India air pollution kills half a million per year, costs hundreds of billions – study - RT
- January 2016: Particular about particulates - The Economist
- January 2016: Researchers find shared molecular response to tobacco smoke and indoor air pollution Boston University Medical Center, EurekAlert: The Global Source of Science News "People who frequently use smoky bituminous coal for heating and cooking could be at a higher risk of developing lung cancer, a new study has found..."
- January 2016: How Do You Fight The World's 'Largest Environmental Health Problem'? Harness The Sun. - The Huffington Post
- August 2015: Air pollution killing 4,000 people a day in China - Climate Action
- March 2015: The Burning Question - Heifer International
- January 2015: Prevalence of chronic obstructive pulmonary disease and associated risk factors in Uganda (FRESH AIR Uganda): a prospective cross-sectional observational study - Lancent Global Health
- September 2014: Household air pollution and lung cancer in China: a review of studies in Xuanwei - Chinese Journal of Cancer
- May 2014: Global health: Deadly dinners Polluting biomass stoves, used by one-third of the global population, take a terrible toll. But efforts to clean them up are failing - Nature
- September 2013: Biomass fuel use for household cooking in Swaziland: is there an association with anaemia and stunting? - WASHplus Project
- January 2013: Improving Cook Stoves Helps Combat Global Climate Change - Aid for Africa
- January 2013: Burning Fuel Particles Do More Damage to Climate Than Thought - New York Times
- October 2011: A Trek for Cleaner Cookstoves - New York Times
- October 2011: Curbing Cooking Smoke That Kills More People Than Malaria - National Public Radio (NPR)
- January 2011: Home fires: The world's most lethal pollution - The Independent
- September 2010: UN-backed ‘clean stove’ initiative to save lives and heal environment - UN News Centre
- World map showing deaths from household air pollution using solid fuels. - World Health Organization, 2005
- Household air pollution articles and publications list - World Health Organization
- Indoor air pollution and houshold energy resource portal - The Health and Envrionment Linkages Initiative (HELI)
- August 2008: WHO confirms dangers of indoor air pollution & unsafe water - Solar Cooker Review
- September 2007: Exposure to indoor fire smoke kills 1.6 million annually - Reuters
- April 2005: Mortality and Greenhouse Gas Impacts of Biomass and Petroleum Energy Futures in Africa - Science
- May 2003: How Charcoal Fires Heat the World - American Chemical Society
- March 2003: Greenhouse Gas Implications of Household Energy Technology in Kenya - Environmental Science and Technology
- Indoor Smoke: Breaking Down Respiratory Defences - World Health Organization's new world map that shows the health impact smoke-filled kitchens have on women and children.
- Fuel for Life: Household Energy and Health - World Health Organization (2006)
- Indoor air polution in developing countries: a major environmental and public health challenge - World Health Organization (2000)
- Cooking smoke: a pervasive killer in developing countries. - WIN News 01/01/98
Audio and video
- January 2017: Can a cleaner cookstove save lives? - PBS Newshour
- January 2017:
- March 2013:
- September 2011:
- Partnership for Clean Indoor Air
- Smoke in the Kitchen: Health Impacts of Indoor Air Pollution in Developing Countries
- WHO factsheet on Household air pollution and health
- Issue #22 of the PCIA Bulletin from the Partnership for Clean Indoor Air is dedicated to the role that solar cooking can play in reducing household air pollution
- Indoor Air Pollution Meter
- New country-by-country data show in detail the impact of environmental factors on health, World Health Organization
- Achieving a cleaner, more sustainable and healthier future, World Health Organization
- http://cleancookstoves.org/resources/495.html, Global Alliance for Clean Cookstoves Progress Report (6 December 2016)
- http://cleancookstoves.org/resources/495.html, Global Alliance for Clean Cookstoves Progress Report (6 December 2016)
- Curbing Cooking Smoke That Kills More People Than Malaria, National Public Radio
- Burden of disease from Household Air Pollution for 2012, World Health Organization