Ceramic cookstoves in sub-Saharan Africa are proving effective at easing some health symptoms associated with inhalation of smoke and other pollutants from traditional cooking fires. But a key metric of health in children -- pneumonia burden -- appears to be unaffected by the stoves' deployment in one western Kenyan district.
Those findings, from Emory University and the U.S. Centers for Disease Control and Prevention and published in the latest American Journal of Tropical Medicine and Hygiene, cast doubt on the ability of some higher-efficiency cookstoves to significantly improve the health of young children, according to the researchers.
At the same time, an interdisciplinary team of researchers from 50 countries published updated figures last week suggesting that household air pollution generated by cookstoves kills an estimated 4 million people each year, twice the level previously believed. Those findings, published in the journal Lancet as part of the latest "Global Burden of Disease" report, were received with alarm by public health advocates who have worked for years to improve cooking conditions in the developing world.
Radha Muthiah, executive director of the Washington, D.C.-based Global Alliance for Clean Cookstoves, called the updated mortality figure on household air pollution "shocking," adding that it "necessitates a redoubling of alliance efforts to ensure that cooking a meal is a life-enriching, and not life-taking, activity for all people."
Kirk Smith, a professor of global environmental health at the University of California, Berkeley, and a co-author of the Lancet article, echoed Muthiah's concern, noting that one of the most alarming findings in the new global disease burden findings "is that smoke from cooking fires was found to be the largest environmental threat to health in the world today."
A closer look at one stove type
The Emory-CDC study focused on one variety of more efficient, ceramic cookstove currently used in western Kenya. And although its findings were not comprehensive, the research suggests that improving indoor air pollution for several billion of the world's poorest could prove far more difficult than once believed.
And coupled with the latest findings on indoor air quality's role in global disease burden, the research provides a clarion call for governments, health agencies, nonprofit organizations and independent researchers to continue refining the design, manufacture and deployment of cleaner-burning cookstoves.
The study found that women who used one brand of unvented stove, known in Swahili as upesi jiko, reported that the units produced less smoke than traditional "three-stone" fire pits, in part because they required less fuel to cook. And some inhalation symptoms, such as stinging eyes and runny noses, were less pronounced when the stoves were used.
Even so, researchers found the stoves reduced air pollution by only 13 percent over traditional fires, and they made no significant difference in the rate of pneumonia in children under 3 years of age.
"Despite requiring less fuel, these stoves may not burn clean enough," said Robert Quick, a co-author of the Kenya paper and researcher in the CDC's Division of Waterborne, Foodborne and Enteric Diseases. "The belief is that you need much more efficient burning, with a reduction in small particles [of less than 2.5 microns] of 50 percent or more, to really observe the health benefits."
Limitations and caveats
The study came with some limitations, however, including a relatively small number of participating households and a lack of a randomized sample. Also, its findings were based on observations of pneumonia symptoms rather than X-rays or other objective measures of the disease.