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 (O3) and particulate matter (PM) pollution in the atmospheric environment, this study obtained emission factors of O3 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 O3 (RSM-O3_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, O3 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 μg/m3 to 48.23 μg/m3 and 38.60 μg/m3, 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 O3concentrations, while primary PM was crucial in controlling PM pollution.