LAUSR

Abstract Biomass burning constitutes a major source of ambient PM2.5 but also a predominant source of indoor PM2.5. Carbonaceous matters, such as organic carbon (OC), elemental carbon (EC), black carbon, and brown carbon (BrC), are major components of PM2.5, and are of broad concern due to their significant impacts on health and climate patterns. In this study, we took simultaneous indoor and outdoor emission measurements to quantify pollutant emission factors (EFs) of carbonaceous matters, including the stack and fugitive EFs, from the real-world biomass burning in rural households. Modified combustion efficiency, fuel moisture, burning rates, and chimney gas velocity explained 45–71% of variations in the field-based emission factors. BrC (measured at 370 nm, and estimated based on the specific attenuation coefficients-16.6 m2/g at 880 nm and 39.5 m2/g at 370 nm) comprised up to ~20% of all OC. Fractions of fugitive emissions of the total reached as high as 44–48%. Fugitive emissions would result in very high peak concentrations of approximately tens of mg/m3, leading to severe indoor air pollution. The study clearly demonstrates that the simultaneous studies on indoor and outdoor emissions and air quality is crucial to understand mechanisms of the environmental impacts of internal combustion sources.