# **Executive Summary**

Poor households in Bangladesh depend heavily on wood, dung and other biomass fuels for cooking. This paper provides a detailed analysis of the implications for indoor air pollution, drawing on new monitoring data for respirable airborne particulates (PM10) in a large number of Bangladeshi households. Concentrations of 300 ug/m<sup>3</sup> or greater are common in our sample, implying widespread exposure to a serious health hazard. For comparison, Galassi, Ostro, et al. (2000) find substantial health benefits for PM10 reduction in eight Italian cities whose annual concentrations are far lower: 45-55 ug/m<sup>3</sup> .

As expected, our econometric results indicate that fuel choice significantly affects indoor pollution levels: Natural gas and kerosene are significantly cleaner than biomass fuels. However, household-specific factors apparently matter more than fuel choice in determining PM10 concentrations. In some biomass-burning households, concentrations are scarcely higher than in households that use natural gas. Our results suggest that cross-household variation is strongly affected by structural arrangements: cooking locations, construction materials, and ventilation practices.

To assess the broader implications for poor Bangladeshi households, we extrapolate our regression results to representative household samples from rural, peri-urban and urban areas in six regions: Rangpur in the Northwest, Sylhet in the Northeast, Rajshahi and Jessore in the West, Faridpur in the Center, and Cox’s Bazar in the Southeast. Our results indicate great geographic variation, even for households in the same per capita income group. This variation reflects local differences in fuel use and, more significantly, construction practices that affect ventilation. For households with per capita incomes less than $1.00/day, rural PM10 concentrations vary from 410 ug/m<sup>3</sup> in Cox’s Bazar to 202 ug/m<sup>3</sup> in Faridpur. In urban areas, concentrations for such households differ by almost 100 ug/m<sup>3</sup> between the highest areas, Jessore and Rajshahi, and the lowest, Sylhet. The poorest households in Faridpur face a lower mean indoor concentration (202 ug/m<sup>3</sup> ) than the highest-income households in Jessore and Rajshahi (215 ug/m<sup>3</sup> ).

Great variation also characterizes the 24-hour cycle within households. For example, within the “dirtiest” firewood-using household in our sample, readings over the 24-hour cycle vary from 68 to 4,864 ug/m<sup>3</sup> . Such variation occurs because houses can recycle air very quickly in Bangladesh. After the midday meal, when ventilation is common, air quality in many houses goes from very dirty to reasonably clean within an hour. Rapid change also occurs within households: Diffusion of pollution from kitchens to living areas is nearly instantaneous in many cases, regardless of internal space configuration, and living-area concentrations are almost always in the same range as kitchen concentrations. By implication, exposure to dangerous indoor pollution levels is not confined to cooking areas.

We find that distinguishing between indoor and outdoor pollution may not be useful in biomass-using areas. In Dhaka, the 24-hour pattern of indoor PM10 concentration for the 1