Indoor Volatile Toxic Organics from Incomplete Burning of Solid Fuels in China

Abstract

Incomplete burning of solid fuels in residential stoves emits various hazardous air pollutants, including some volatile toxic organic compounds, to ambient and indoor air. Due to high spatiotemporal variations in combustion emissions and household characteristics, indoor pollution of volatile organic compounds (VOCs) is poorly characterized, especially due to a lack of a nationwide assessment. Here, a field campaign was conducted to evaluate indoor emissions of 37 VOCs, including chlorinated hydrocarbons, aromatics, and chlorinated aromatics, for representative fuel-stove combinations in use for China, and real-world emission rates were used to assess indoor VOC pollution using a single-zone model. VOCs from the solid fuel burning in vented stoves leaked into indoor space substantially, with more leakages for high-molecular-weight VOCs (p < 0.01). In rural China, on the national scale, the simulated 24 h average indoor concentration attributed to residential solid fuel burning was 11.6, 1.76, and 0.28 μg/m³ for benzene, naphthalene, and trichloroethylene, respectively. Approximately 85% of households had indoor benzene concentrations exceeding the WHO guideline of 1.7 μg/m³, while the exceedance of naphthalene and trichloroethylene attributed to indoor fuel combustion emissions was much more limited. Higher indoor VOC contamination was in northern and northeastern China, where large amounts of coal were burned inefficiently for daily energy demands.