Primary particulate matter emissions and estimates of secondary organic aerosol formation potential from the exhaust of a China V diesel engine

Vehicle emissions contribute to ambient particulate matter (PM) pollution directly via emissions of PM and indirectly by secondary aerosol formation, as a result of trace gas emissions. In this paper, we determined the emission factors of primary pollutants and estimated the secondary organic aerosol (SOA) formation potential of a China V heavy-duty diesel engine tested under ETC (European Transient Cycle) and ESC (European Stationary Cycle) with different types of fuels using an engine dynamometer. Volatile organic compounds (VOCs) emission factors were 55.7-121 mg/kwh, while primary PM emission factors were 15.0-26.8 mg/kwh. These values were substantially lower than those of older diesel vehicles that met pre-China V standards. Based on the SOA yields of the measured VOCs, the SOA formation potential of diesel engines were estimated to be 2.8-15.9 mg/kg fuel. The ratios of potential SOA/primary PM ranged from 0.07 to 0.16. We further showed that VOCs emission factors, SOA formation potential and the ratios of SOA/primary PM were highly dependent on the test cycle, whereas the primary PM emission factors on both test cycles and fuel quality.