Air pollution dispersion from biomass stoves to neighboring homes in Mirpur, Dhaka, Bangladesh

Background: Indoor air pollution, including fine particulate matter (PM _2.5 ) and carbon monoxide (CO), is a major risk factor for pneumonia and other respiratory diseases. Biomass-burning cookstoves are major contributors to PM _2.5 and CO concentrations. However, high concentrations of PM _2.5 (> 1000 μg/m ³ ) have been observed in homes in Dhaka, Bangladesh that do not burn biomass. We described dispersion of PM _2.5 and CO from biomass burning into nearby homes in a low-income urban area of Dhaka, Bangladesh. Methods: We recruited 10 clusters of homes, each with one biomass-burning (index) home, and 3-4 neighboring homes that used cleaner fuels with no other major sources of PM _2.5 or CO. We administered a questionnaire and recorded physical features of all homes. Over 24 h, we recorded PM _2.5 and CO concentrations inside each home, near each stove, and outside one neighbor home per cluster. During 8 of these 24 h, we conducted observations for pollutant-generating activities such as cooking. For each monitor, we calculated geometric mean PM _2.5 concentrations at 5-6 am (baseline), during biomass burning times, during non-cooking times, and over 24 h. We used linear regressions to describe associations between monitor location and PM _2.5 and CO concentrations. Results: We recruited a total of 44 homes across the 10 clusters. Geometric mean PM _2.5 and CO concentrations for all monitors were lowest at baseline and highest during biomass burning. During biomass burning, linear regression showed a decreasing trend of geometric mean PM _2.5 and CO concentrations from the biomass stove (326.3 μg/m ³ , 12.3 ppm), to index home (322.7 μg/m ³ , 11.2 ppm), neighbor homes sharing a wall with the index home (278.4 μg/m ³ , 3.6 ppm), outdoors (154.2 μg/m ³ , 0.7 ppm), then neighbor homes that do not share a wall with the index home (83.1 μg/m ³ ,0.2 ppm) (p = 0.03 for PM _2.5 , p = 0.006 for CO). Conclusion: Biomass burning in one home can be a source of indoor air pollution for several homes. The impact of biomass burning on PM _2.5 or CO is greatest in homes that share a wall with the biomass-burning home. Eliminating biomass burning in one home may improve air quality for several households in a community.