Evaluating six biomass stoves: the Kenya experience
A comprehensive field evaluation of six models of biomass cookstoves was conducted in Kenya to assess their public health benefits and factors that can contribute to their effectiveness as a health intervention in communities.
The study – funded in part by the Alliance with support from the Morgan Stanley Foundation – evaluated the biomass cookstoves against a three-stone fire as a baseline. It was conducted by by the U.S. Centers for Disease Control and Prevention (CDC), and the Kenya Medical Research Institute (KEMRI), in partnership with the Global Alliance for Clean Cookstoves, the World Health Organization (WHO), the US Environmental Protection Agency (US EPA), the California Public Health Institute, and the Safe Water and AIDS Project (SWAP).
• Women participating in this evaluation expressed a real interest in adopting clean and safe cooking towards clean cooking technologies.
• Adoption of clean and safe cooking in rural Kenya requires addressing a complex mix of factors that include: stove design and performance, women’s cooking needs and preferences, other sources of indoor air pollution, fuel mix and moisture content, lack of ventilation, and the availability and cost of new cookstoves.
• All cookstoves evaluated reduced emissions compared to the three-stove baseline, but not to the point expected to maximize the public health benefit to the community.
• To achieve clean and safe cooking as a goal, cookstove programs need a comprehensive approach to address the multiple factors that contribute to reducing emissions: cookstove design and performance, use of clean fuels, effective strategies to ensure adoption, addressing other potential sources of emissions, availability and cost of cookstoves, and ventilation.
• There is also need to conduct comprehensive field evaluations of new cooking technologies that are intended to reduce cookstove emissions and the risk of burns. The promotion of clean cookstoves should be linked to health standards and evaluated against these standards.
• Clean fuel technologies hold promise for addressing a number of the factors needed to achieve clean cooking but were not evaluated in this study. This is a gap that needs to be addressed.
The project was conducted in two rural villages in Nyando Province, Kenya. A total of 45 homes in each village were selected to participate in the two-year study. These communities have some of the highest rates of childhood respiratory illness in Kenya and 99% of homes use a three-stone fire for cooking. The study was designed so that all homes would use each stove, with the cookstove changed out approximately every month. This resulted in six rounds of data collection plus the initial baseline data collection.
The evaluation included community focus groups to assist in selection of the stoves, U.S. EPA laboratory evaluation of stoves, monitoring on all cooking devices and the kitchen wall, pre- and post-round home interviews with the primary cook in the home, community health worker visits, each primary cook keeping a log of cooking events, a kitchen performance test conducted during each round in each home, emission and exposure monitoring in each round in each home, ambient air monitoring in the community, pre- and post-round collection of urine specimens on mother and one child in the home to test for a biomarker of exposure, and focus groups at the beginning and the end of the evaluation period.
Initial analysis of women’s preferences point to a high degree of interest in greater access to cleaner and safer cookstoves. Each stove tested brought down emissions from cooking in the home, but not to the point expected to maximize the public health benefit to the community. Many reasons may contribute to this result, including: the cookstove design and women’s needs or use; documented stove stacking in homes; household variation in stove use and performance; the use of kerosene lamps for lighting; fuel moisture content; and lack of ventilation.
As the cookstove sector moves to scale its efforts globally, clean and safe cooking solutions should be comprehensively evaluated in communities to better understand the factors that contribute to achieving the maximum public health benefit. As a potential public health intervention there is also a priority need to comprehensively evaluate clean fuel technologies in communities.
Journal publication of full study results is scheduled for early fall 2014.
– Mike Sage, guest researcher, U.S. Centers for Disease Control and Prevention