Fugitive Emissions of CO and PM2.5 from Indoor Biomass Burning in Chimney Stoves Based on a Newly Developed Carbon Balance Approach

Fugitive emissions of smoke from stoves directly affect indoor air quality. However, this important process has been very scarcely evaluated so far. In this study, a novel approach has been developed to quantify fugitive emissions in the field, and for the first time, field-based fugitive emission factors (EFs) and fugitive fractions of carbon monoxide (F-CO) and fine particulate matter (PM2.5) (F-PM2.5) from indoor biomass burning in the real world are reported. Fugitive EFs were more likely log-normally distributed and positively correlated to the stack and total EFs. The calculated F-CO and F-PM2.5 were 13.5 +/- 10.3% and 27.9 +/- 13.7%, respectively, which were higher than those determined in laboratory studies. Fugitive fractions were normally distributed, and the mean F-PM2.5 was close to the assumed value of 25% in the World Health Organization Guidelines for Indoor Air Quality: Household Fuel Combustion; however, the F-CO was significantly lower than 25%. The total EFs calculated on the basis of the traditional carbon mass balance method were positively correlated with the total summarized from fugitive and stack emissions but were considerably underestimated, especially for PM2.5 as the mixing ratio of PM2.5 to carbon dioxide in fugitive emissions was found to be higher than that in the chimney exhaust.