Indoor Nitrogen Dioxide in Homes with Biomass Cookstoves before and after a Gas Stove Intervention

摘要

Emissions from biomass-fueled cookstoves are the largest environmental contribution to the global burden of disease, responsible for 2.6 million deaths annually. A transition from biomass to liquified-petroleum gas (LPG) cookstoves has been proposed as a global public health intervention. While this transition seems likely to reduce fine particulate matter and carbon monoxide, very little is known about cookstove-related emissions of nitrogen dioxide (NO2), a threat to respiratory health. Assessing exposure to NO2 from biomass and LPG cookstoves is essential to understand the public health risks posed by biomass cookstoves and inform the current promotion of LPG as a healthier alternative to biomass fuel. This study aims to 1) quantify NO2 exposure from biomass cookstoves and 2) assess changes in NO2 exposure after the transition from biomass to LPG cookstoves. We will measure NO2 concentrations in 100 kitchens with biomass cookstoves in rural Puno, Peru. Concentrations will be sampled by direct-reading instruments at one-minute intervals for 48 hours, allowing us to quantify both daily mean concentrations and short-term concentration peaks associated with cooking events. To assess the effect of transitioning from biomass to LPG on kitchen NO2 concentrations, we will randomize 50 of these households to receive free LPG stoves and fuel and 50 households to serve as a control. We will measure NO2 concentrations three months post-intervention. In our study setting, homes with biomass cookstoves experienced daily NO2 concentrations [48-hour mean (sd): 139 ppb (92), n=99] well above the WHO indoor annual guideline (21 ppb). Acute exposures were also elevated, as 26% of kitchen-hours [1-hour mean (sd): 139 ppb (252), n=2376 hours] were above the WHO indoor hourly guideline (105 ppb). Transitioning from biomass to LPG cookstoves reduced daily NO2 concentrations by 40%, however these concentrations [mean (sd): 73 ppb (47), n=40] remain above the WHO annual guideline (21 ppb).