Domestic biomass fuel combustion and chronic bronchitis in two rural Bolivian villages.

BACKGROUND Chronic bronchitis is an important public health problem worldwide. A study was undertaken to examine the association between exposure to air pollution from domestic biomass fuel combustion and chronic bronchitis in two rural Bolivian highland villages: a village in which cooking is done exclusively indoors and a village in which cooking is done primarily outdoors. Apart from this difference, the villages were virtually identical in terms of socioeconomic status, climate, altitude, access to health care, and other potential confounders. METHODS Pollution exposure was assessed by combining information on concentrations of particulate matter of <10 microm diameter (PM(10)) in 12 randomly selected households in each village in all potential microenvironments of exposure with time allocation information. The prevalence of chronic bronchitis was assessed using the British Medical Research Council's questionnaire on individuals >20 years of age in both villages (n = 241). RESULTS Daily pollution exposure was significantly higher in the indoor cooking village (range for adults: 9840-15 120 microg-h/m(3)) than in the outdoor cooking village (range for adults: 5520-6240 microg-h/m(3)) for both seasons and for men and women. The overall prevalence of chronic bronchitis was 22% and 13% for the indoor and outdoor cooking villages, respectively. Logistic regression analysis, which excluded the few smokers present in the population, showed a 60% reduced risk of chronic bronchitis in the outdoor cooking village compared with the indoor cooking village (OR 0.4; 95% CI 0.2 to 0.8; p = 0.0102) after adjusting for age and sex. Individuals aged >40 years were 4.3 times more likely to have chronic bronchitis than the younger age group (OR = 4.3; 95% CI 2.0 to 9.3; p = 0.0002). There was no significant difference in the prevalence of chronic bronchitis in men and women. CONCLUSIONS The results of this study suggest an association between chronic bronchitis and exposure to domestic biomass fuel combustion, but further large scale studies from other areas of the developing world are needed to confirm the association. Results from this and other studies will assist the development of culturally acceptable and feasible alternatives to the high exposure cooking stoves currently being used by most people worldwide.