Biomass solid fuel and acute respiratory infections: the ventilation factor.

Biomass solid fuel smoke is linked to acute respiratory infections (ARI). In future, its use will likely increase among poor households, and better ventilation is one important measure that can reduce this health impact. The authors aimed to study the extent to which improvement in ventilation-related factors reduces the fraction of ARI attributable to exposure to biomass smoke in children under 5 years old. An explorative study was carried out in 2004 by applying a questionnaire on 51 households randomly selected from a health district in Burkina Faso. The prevalence of exposure in the population was estimated using ventilation coefficients, and proportions of households with different stove types and locations. An attributable fraction of 0.56 (95% CI: 0.47-0.62) was estimated using the traditional formula for attributable fraction, and 0.26 (95% CI: 0.19-0.31) after weighting exposure by ventilation coefficients, stove type and location. Two scenarios were created: (1) Assuming that most households cooked inside, the fraction becomes 0.54 (95% CI: 0.45-0.61). (2) Assuming that indoor ventilation and cooking device are improved by 20%, the fractions decreased slightly. Improving cooking devices and indoor ventilation reduces the fraction of ARI in children under 5 years attributable to exposure to biomass smoke, but a higher reduction is achieved by cooking outdoors.