Pneumonia and exposure to household air pollution in children under the age of 5 years in rural Malawi findings from the Cooking And Pneumonia Study

Abstract

Background Exposure to household air pollution is associated with an increased risk of pneumonia in children in low- and middle-income countries, however exposure-response data are limited and there are uncertainties around the extent to which biomass-fueled cookstoves can reduce these exposures. Research question What is the association between exposure to household air pollution and pneumonia in children under the age of 5 years in rural Malawi and what are the effects of a biomass-fueled cookstove intervention on personal exposure to household air pollution? Study design and methods We measured personal exposure to carbon monoxide (CO) [48 hours of continuous measurement and transcutaneous carboxyhemoglobin (COHb)] 6-monthly in children participating in a cluster-randomised controlled trial of a cleaner-burning biomass-fueled cookstove intervention to prevent pneumonia in children under the age of 5 years in rural Malawi – the Cooking And Pneumonia Study (CAPS). Exposure-response and multi-variable analyses were done. Results We recruited 1805 (928 intervention; 877 control) children (mean age 25.6 months, 50.6% female). We found no evidence of an association between exposure to CO (IRR=1.0 95% CI:0.967-1.014; p=0.53) or COHb (IRR=1.00 95% CI:0.993-1.003; p=0.41)) in children who experienced pneumonia versus those who did not. Median exposure to CO in the intervention and control groups was was 0.34 ppm (IQR 0.15-0.81) and 0.37 ppm (IQR 0.15-0.97), respectively. The group difference in means was 0.46 (95% CI:-0.95-0.012; p=0.06). Interpretation Exposure to CO in our population was low with no association seen between exposure to CO and pneumonia incidence and no effect of the CAPS intervention on these exposures. These findings suggest that CO may not be an appropriate measure of household air pollution exposure in settings like rural Malawi and that there is a need to develop ways to directly measure particulate matter exposures in young children instead.