Inexpensive, locally-produced ceramic cookstoves may produce less smoke than traditional indoor 3-stone firepits, but they don't significantly reduce indoor air pollution or the risk of pneumonia in young children, according to results from a small, year-long observational study by researchers working in rural Kenya.
The findings, published online today in the American Journal of Tropical Medicine and Hygiene, are the first to examine the health impacts of ceramic cookstoves that do not vent smoke to the outside of the house, said Robert Quick, MD, MPH, a researcher in the Division of Waterborne, Foodborne, and Enteric Diseases at the U.S. Centers for Disease Control and Prevention.
Women who used the ceramic stoves (called "upesi jiko," which is Swahili for "quick stove") reported less smoke in their homes, along with fewer stinging eyes and runny noses. However, the study found that even though there were fewer respiratory symptoms, these stoves only reduced air pollution by 13 percent and there was no significant difference in pneumonia among children under 3 years of age in these homes when compared to those in homes with 3-stone firepits.
Women and their young children bear the brunt of health problems caused by cooking indoors, in inadequately vented spaces, over open fires fueled by unprocessed wood, charcoal or other biomass.
"Despite requiring less fuel, these stoves may not be efficient enough," Quick said. "The belief is that you need much more efficiency, maybe a reduction of 50 percent or more, to really observe the health benefits," he added.
Pneumonia is the leading cause of death for children under 5 years of age in developing countries, with nearly 70 percent of these 1.2 million deaths occurring in Southeast Asia and sub-Saharan Africa. Research has found household air pollution can increase the risk of pneumonia-a 2008 study found that exposure to this type of pollution from burning solid fuel nearly doubled the risk of pneumonia in young children. Very small particles and toxic gases in indoor smoke can inflame the airways and lungs.
Cleaner burning cookstoves are thought to be one way to reduce harmful household air pollution. The Global Alliance for Clean Cookstoves, one of the most prominent public-private partnerships in this area of public health, has raised US $114 million in its goal to put 100 million new stoves into households in the developing world by 2020.
"This support of improved cookstoves is exactly what we need to be seeing on this front, but we also need to be sure that the improved cookstoves are actually improving the air quality in a way that reduces health risks too," Quick added. "There is currently a lot of research activity into the design of cleaner burning cookstoves, including by the Kenya Medical Research Institute and the Centers for Disease Control and Prevention."
At the same time, there is limited evidence that the cookstoves they evaluated can yield health benefits, according to Quick and his colleagues from the Emory University School of Medicine, Kenya's Safe Water and AIDS Project, the Kenya Medical Research Institute and the Centers for Disease Control and Prevention.
For one year, Quick and his colleagues followed the health of children under 3 years of age in 20 villages in the Nyando District of Kenya's Nyanza Province, which were already participating in a water quality study.
Since 2008, households in the district have been able to purchase locally produced upesi jiko stoves, sold at a cost of about 150 Kenya shillings or US $2-3. The researchers looked at how rates of cough, pneumonia, and severe pneumonia differed among the infants, and whether these differences were related to upesi jiko or traditional firepit cooking. The cases of pneumonia were diagnosed by fieldworkers trained to recognize familiar signs of the illness, such as a cough combined with a specific rapid breathing rate, but the cases were not confirmed by x-rays or other objective tests.
The stoves study also was not a randomized controlled trial, Quick noted. The number of homes in the study was relatively small. Also, he and his colleagues found there were lower rates of coughing and pneumonia in households with cell phones, a pattern that is consistent with other studies showing that wealthier households-perhaps due to factors such as better access to health care-have a lower risk of the disease. Future randomized studies that include more households and stoves that burn more cleanly, he said, will help clarify whether improved stoves can really make a difference in children's respiratory health.
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