The improvement of Beijing ambient air quality resulting from the upgrade of vehicle emission standards

To investigate the effects and improvements of tightening vehicle emission standards from China III to China V on ozone (O-3) and particulate matter (PM) pollution in the atmospheric environment, this study obtained emission factors of O-3 and PM precursors such as nitrogen oxides (NOx), volatile organic compounds (VOCs), and primary PM from gasoline and diesel vehicles through actual testing. Response surface models (RSM) were then created for the environmental concentrations of the target pollutants O-3 (RSM-O-3_HSS6-200) and PM (RSM-PM_HSS9-300) as functions of precursor pollutant emissions. Beijing was chosen as the main receptor region, with the China III emission standard serving as the baseline scenario and the China IV and V standards as control scenarios. The results indicate that as vehicle emission standards tightened from China III to China IV and V, O-3 concentrations in Beijing's environment decreased from 92.7 ppbv to 78.47 ppbv and 72.20 ppbv, respectively, while PM concentrations decreased from 64.12 mu g/m(3) to 48.23 mu g/m(3) and 38.60 mu g/m(3), respectively. Furthermore, the environmental benefits achieved from China III to China IV were higher than those from China IV to China V. Additionally, an analysis of pollutant source contributions revealed that NOx played a major role in reducing O-3 concentrations, while primary PM was crucial in controlling PM pollution.