ARB Research Seminar

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Characterization of Indoor Air Quality in Rural Chinese Kitchens and Field Investigation of Village-Scale Clean Energy Interventions

Susan L. Fischer Ph.D., Science, Technology, and Health Policy Advisor to the Chair of the Air Resources Board

July 31, 2007
Cal EPA Headquarters, 1001 "I" Street, Sacramento, CA



Rural kitchens of solid-fuel burning households constitute the microenvironment responsible for the majority of human exposures to health-damaging air pollutants, particularly respirable particles and carbon monoxide. In China alone, 1.06 billion people were exposed to indoor air pollution from household combustion of solid fuels such as coal, wood, and crop straw in 2001. Addressing health impacts through cooking fuel and stove interventions calls for time-resolved data characterizing average indoor air quality and peak pollution episodes, which dominate women's and children's exposures; analysis of fuel, stove, and behavioral factors as determinants of indoor air quality; and field data to substantiate operations and guide implementation of promising technologies.

Portable nephelometers facilitate logistically simple, precise, time-resolved characterization of particles but must contend with aerosols that are highly variable in terms of chemical content, size, and relative humidity. Observations from highly polluted Chinese kitchens, where gravitationally determined 24-h average respirable particle concentrations were as high as 700 mg/m3, showed that where relative humidity remained below 95%, nephelometric response was strongly linear despite complex mixtures of aerosols and variable ambient conditions. Where 95% relative humidity was exceeded for even a brief duration, nephelometrically determined 24-h mean particle concentrations were nonsystematically distorted relative to gravitational data. This nonsystematic distortion is particularly problematic for rural exposure assessment studies, which emphasize upper quantiles of time-resolved particle measurements within 24-h samples.

Time-resolved wintertime measurements of carbon monoxide and respirable particles (RSP) enable exploration of peak pollution periods in a village in Jilin Province, China, characterized by household use of both coal and biomass, as well as several "improved" (gas or electric) fuels. Our data indicate a 6-fold increase in peak 1 h PM (1.9 mg/m3) concentrations relative to 24 h mean PM (0.31 mg/m3). Peak 1 h CO concentrations (20.5 ppm) routinely approached and often (27%) exceeded the World Health Organization's 1 h guideline of 26 ppm, although the vast majority (95%) of kitchens were within China's residential indoor air quality guideline for CO on a 24 h basis. Choice of heating fuel and household smoking status were significant predictors of indoor air quality. Whether solid or "improved" (gas or electric) fuel was used for cooking had an even stronger effect, but in the opposite direction from expected, on both peak and daily average measures of air pollution. Due to the primary role of heating as a determinant of wintertime indoor air quality in northern Chinese villages, health-oriented interventions limited to provision of improved cooking fuel are insufficient.

Chinese national and provincial, as well as international rural development institutions, have identified generation of producer gas from agricultural residues as a promising option for supplying clean-burning, inexpensive, and convenient household energy. Although the technology is promising, field data from village projects are scarce. A team trained in cultural anthropology, environmental health sciences, and engineering recently visited Jilin province, China, to investigate operations of three village-scale producer gas projects. One locally initiated project was operating on a regular basis and supplying a substantial fraction of village cooking needs. The other two projects had not operated since their initial demonstrations. Technical, economic, organizational, and cultural factors, including a lack of evaluative feedback from local projects to provincial level coordinators, hamper the development of village-scale producer gas projects in Jilin province.

Speaker Biography

Susan L. Fischer, Ph.D., M.S.E., was appointed in September 2006 as Science, Technology, and Health Policy Advisor to the Chair of the Air Resources Board (ARB). Prior to joining ARB, Dr. Fischer was a postdoctoral scholar of Environmental Health Sciences at the University of California, Berkeley's School of Public Health, where she managed and conducted an independent field investigation of a rural energy project in Jilin province, China. Dr. Fischer's research in rural China comprised public health inquiry into indoor air quality and its determinants, engineering analysis of particle-monitoring equipment in a rural field context, and ethnographic research on household impacts and socio-cultural dynamics associated with a village-scale energy project.

Dr. Fischer also has experience as a laboratory combustion researcher with Princeton University, where she earned her M.S.E. investigating turbulent flow reactor chemical kinetics of dimethyl ether, a fuel with applications in diesel engines and in household cooking stoves.

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