Analysis of passenger vehicle pollutant emission factor based on on-board measurement

With the increase in the number of vehicles, air pollution in Northeast China raised growing concerns. In order to understand the pollutant emissions of passenger vehicles, this study analyzes the influencing factors of emission factors from both the start-up stage and the operation stage, respectively. It was found that during the start-up stage, the emission factors were mainly influenced by emission standards, fuel type, initial engine temperature and environmental temperature; during the operation stage, the emission factors were mainly influenced by driving speed, road properties and time properties. The analysis shows that the contribution rate of start-up emission can be effectively reduced by increasing the initial engine temperature or using compressed natural gas fuel. In the cold start stage, the CO and NOx emission factors in winter are 23 or 6.37 times of those in autumn. For China 5 light-duty gasoline-fueled vehicle, the operating emission factors of CO2, CO, NOx and VOCs are 247.48 g/km, 0.493 g/km, 0.061 g/km and 0.084 g/km, respectively. For China 4 LDGVs, the operating emission factors of CO2, CO, NOx and VOCs are 252.118 g/km, 3.166 g/km, 0.426 g/km and 0.113 g/km, respectively. For China 5 compressed natural gas-fueled vehicles, the operating emission factors of CO2, CO, NOx and VOCs are 156.304 g/km, 1.131 g/km, 0.945 g/km and 0.477 g/km, respectively. To reduce the pollutant emission factors of vehicles, the government should promote China 6 vehicles and new energy vehicles, optimize the road layouts structure of the square loops and road intersections, and strictly implement the I/M (Inspect Maintenance) regulation.