Gaseous and particulate emissions from rural vehicles in China

Rural vehicles (RVs) could contribute significantly to air pollutant emissions throughout Asia due to their considerable population, extensive usage, and high emission rates, but their emissions have not been measured before and have become a major concern for the accuracy of regional and global emission inventories. In this study, we measured CO, HC, NOx and PM emissions of RVs using a combined on-board emission measurement system on real roads in China. We also compared the emission levels of the twenty RVs to those of nineteen Euro II light-duty diesel trucks (LDDTs) that we measured for previous studies. The results show that one-cylinder RVs have lower distance-based emission factors compared to LDDTs because of their smaller weight and engine power, but they have significantly higher fuel-based PM emission factors than LDDTs. Four-cylinder RVs have equivalent emission levels to LDDTs. Based on the emission factors and the activity data obtained, we estimate that the total emissions of RVs in China in 2006 were 1049 Gg of CO, 332 Gg of HC, 933 Gg of NOx, and 54 Gg of PM, contributing over 40% to national on-road diesel CO, NOx, and PM emissions. As RVs are a significant contributor to national emissions, further research work is needed to improve the accuracy of inventories at all levels, and the government should strengthen the management of RVs to facilitate both policy making and research work.