Motor vehicles emission inventory at county level based on vehicle kilometers travel: a case study of Yanqing District of Beijing

Vehicle type, environmental condition, vehicle mileage and fuel type of motor vehicles in Yanqing District were surveyed and calculated. The COPERT model was used to compute the emission factors of CO, HC, NO_x and PM for passenger cars, buses, small trucks, medium trucks and oversized trucks, respectively. Geographic information system was applied to establish high-resolution exhaust emissions inventory, based on vehicle driving range (VKT) database in Yanqing District obtained by field investigation and Google Earth satellite image. Then the vehicle kilometers travel data and the corresponding pollutants emission were calculated by actual traffic information. The results showed that the annual emission of CO, HC, NO_x and PM was respectively 1 995.49, 478.84, 2 466.06 and 156.65 t/a. Specifically, passenger cars had a higher contribution to CO and HC, which accounted for 36% and 72%, while the oversized trucks had a higher contribution to NO_x and PM, which accounted for 54% and 49%, respectively. High emissions were mainly distributed in the downtown area due to dense road network and larger traffic volume flow.