Kitchen PM2.5 concentrations and child acute lower respiratory infection in Bhaktapur, Nepal: The importance of fuel type

Background: Globally, solid fuels are used by about 3 billion people for cooking and a smaller number use kerosene. These fuels have been associated with acute lower respiratory infection (ALBS) in children. Previous work in Bhaktapur, Nepal, showed comparable relationships of biomass and kerosene cooking fuels with ALRI in young children, compared to those using electricity for cooking. We examine the relationship of kitchen PM2.5 concentrations to ALRI in those households. Methods: ALRI cases and age-matched controls were enrolled from a cohort of children 2-35 months old. 24-h PM2.5 was measured once in each participant's kitchen. The main analysis was carried out with conditional logistic regression, with PM2.5 measures specified both continuously and as quartiles. Results: In the kitchens of 393 cases and 431 controls, quartiles of increasing PM2.5 concentration were associated with a monotonic increase in odds ratios (OR): 1.51 (95% CI: 1.00, 2.27), 2.22 (1.47, 3.34), 2.48 (1.63, 3.77), for the 3 highest exposure quartiles. The general kitchen concentration-response shape across all stoves was supralinear. There was evidence for increased risk with biomass stoves, but the slope for kerosene stoves was steeper, the highest quartile OR being 5.36 (1.35, 21.3). Evidence for increased risk was also found for gas stoves. nclusion: Results support previous reports that biomass and kerosene cooking fuels are both ALRI risk factors, but suggests that PM2.5 from kerosene is more potent on a unit mass basis. Further studies with larger sample sizes and preferably using electricity as the baseline fuel are needed.