Emission Factors of Particulate Matter and Elemental Carbon for Crop Residues and Coals Burned in Typical Household Stoves in China

Both particulate matter (PM) and black carbon (BC) impact climate change and human health. Uncertainties in emission inventories of PM and BC are partially due to large variation of measured emission factors (EFs) and lack of EFs from developing countries. Although there is a debate whether thermal-optically measured elemental carbon (EC) may be referred to as BC, EC is often treated as the same mass of BC. In this study, EFs of PM (EFPM) and EC (EFEC) for 9 crop residues and 5 coals were measured in actual rural cooking and coal stoves using the carbon mass balance method. The dependence of the EFs on fuel properties and combustion conditions was investigated. It was found that the mean EFPM were 8.19 +/- 4.27 and 3.17 +/- 4.67 g/kg and the mean EFEC were 1.38 +/- 0.70 and 0.23 +/- 0.36 g/kg for crop residues and coals, respectively. PM with size less than 10 mu m (PM10) from crop residues were dominated by particles of aerodynamic size ranging from 0.7 to 2.1 mu m, while the most abundant size ranges of PM10 from coals were either from 0.7 to 2.1 pin or less than 0.7 mu m. Of various fuel properties and combustion conditions tested, fuel moisture and modified combustion efficiency (MCE) were the most critical factors affecting EFPM and EFEC for crop residues. For coal combustion, EFPM were primarily affected by MCE and volatile matter, whereas EFEC were significantly influenced by ash content, volatile matter, heat value, and MCE. It was also found that EC emissions were significantly correlated with emissions of PM with size less than 0.4 mu m.