Non-Communicable Respiratory Disease and Air Pollution Exposure in Malawi (CAPS): A Cross-Sectional Study

Background Non-communicable respiratory diseases and exposure to air pollution are thought to be important contributors to morbidity and mortality in sub-Saharan African adults. Methods We did a cross-sectional study among adults in communities participating in a randomised controlled trial of a cleaner-burning biomass-fuelled cookstove intervention (CAPS) in rural Malawi. We assessed chronic respiratory symptoms, spirometric abnormalities, personal exposure to air pollution (fine particulate matter (PM2.5) and carbon monoxide (CO)). Weighted prevalence estimates were calculated; multivariable and intention-to-treat analyses were done. Results 1481 participants (mean (SD)) age 43·8 (17·8)) 57% female) were recruited. The prevalence of chronic respiratory symptoms, spirometric obstruction and restriction were 13·6% (95% CI:11.9-15.4), 8·7% (95% CI:7·0-10·7) and 34·8% (95% CI:31·7-38·0), respectively. Median 48-hour personal PM2.5 and CO exposures were 71·0 μg/m3 (IQR:44·6-119·2) and 1·23 ppm (IQR:0·79-1·93), respectively. Chronic respiratory symptoms were associated with current/ex-smoking (OR=1·59 (95% CI:1·05-2·39)), previous TB (OR=2·50 (95% CI:1·04-15·58)) and CO exposure (OR=1·46 (95% CI:1·04-2·05)). Exposure to PM2.5 was not associated with any demographic, clinical or spirometric characteristics. There was no effect of the CAPS intervention on any of the secondary trial outcomes. Conclusion The burden of chronic respiratory symptoms, abnormal spirometry and air pollution exposures in adults in rural Malawi is of considerable potential public health importance. We found little evidence that air pollution exposures were associated with chronic respiratory symptoms or spirometric abnormalities and no evidence that the CAPS intervention had effects on the secondary trial outcomes. More effective prevention and control strategies for non-communicable respiratory disease in sub-Saharan Africa are needed.