Comparison of emissions and residential exposure from traditional and improved cookstoves in Kenya

Suspended particulate matter and carbon emissions from the combustion of biomass, in addition to their environmental consequences, have been causally associated with the incidence of respiratory and eye infections. Improved stoves offer the potential for emissions reduction. We compare the emissions of suspended particulate matter and carbon monoxide from traditional and improved biofuel stoves in Kenya under the actual conditions of household use. Data for analysis is from 137 14-h days of continuous real-time emission concentration monitoring in a total of 38 households. Our analysis shows that improved (ceramic) wood-burning stoves reduce daily average suspended particulate matter concentration by 48% (1822 μg/m3; 95% C.I. 663-2982) during the active burning period and by 77% (1034 μg/m3; 95% C.I. 466-1346) during the smouldering phase. Ceramic stoves also reduce the median and the 75th and 95th percentlies of daily emission concentration during the burning period and the 95th percentile during the smouldering phase, and therefore shift the overall emission profile downward. Improved charcoal-burning stoves also offer reductions in indoor air pollution compared to the traditional metal stove, but these are not statistically significant. The greatest reduction in emission concentration is achieved as a result of transition from wood to charcoal where mean emission concentrations drop by 87% (3035 μg/m3; 95% C.I. 2356-3500) during the burning period and by 92% (1121 μg/m3; 95% C.I. 626-1216) when smouldering as well as large reductions in the median and 75th and 95th percentiles. These results indicate that transition to charcoal, followed by the use of improved wood stoves, are viable options for reduction of human exposure to indoor air pollution in many developing nations.