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 (RSMPM_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 environmetal 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 O3 concentrations, while primary PM was crucial in controlling PM pollution.

Urea regulators (UR) have generally been employed against diesel trucks to save urea usage and thus contribute to the reduction in excessive emissions, while their usage is generally difficult to supervise and enforce. By conducting real driving emission measurements on a China IV heavy-duty diesel truck, a “trade-off” effect caused by UR was found between nitrogen oxides (NOx) and particle number (PN) emissions. The usage of UR contributes to 1.04 times higher NOx but 0.28 times lower PN emissions for the whole trip. In particular, the increasing effects on NOx are most efficient on the highway and least effectual on the urban road, while the decreasing effects on PN exhibit an opposite trend under different road types. From low- and medium- to the high-speed bin, the peak average vehicle-specific power NOx emission rates exhibit markedly increasing but slightly decreasing trends for the truck with and without UR, respectively. Furthermore, the NOx emissions in units of CO₂ and the linear correlational relationship between CO₂ and NOx instantaneous mass emission rates, especially those on the highway, are significantly enhanced. This study directly clarifies the effects of UR on real-world emissions, providing a scientific basis for the real-time identification of the malfunction of the selective catalytic reduction system.

In this study, a bench test was conducted employing the Worldwide Harmonized Light-duty Vehicles Test Cycle (WLTC) to investigate the emission rates of hydrocarbons (HCs), carbon monoxide (CO), and carbon dioxide (CO₂) with two different gasolines and five gasoline vehicles. The results indicated that compared with X gasoline, X+ gasoline led to a reduction in the emission rates of HC, CO, and CO₂, by 38%, 11%, and 7%, respectively, attributed to its lower aromatic hydrocarbon content, olefin content, and 90% evaporation temperature (T90), and higher oxygen content. X+ gasoline exhibited more emission reductions under both acceleration and deceleration conditions. The two gasolines showed consistent patterns: for X+ gasoline, the emission rates under acceleration conditions were significantly higher than those under deceleration conditions, by a factor of 14.9, 2.1, and 1.6 for HC, CO, and CO₂, respectively. Stronger Spearman correlations between vehicle specific power (VSP) and the emission rates were observed at higher speed (>80 km/h) of X, than those at medium speed (40–80 km/h) and lower speed (≤40 km/h), for both gasolines. Overall, the grey relation analysis revealed obvious heterogeneity between each of the seven fuel properties (RON, T10, T50, T90, Oxygen content, Aromatics content, Olefin content) and each of the three emission rates. However, slightly higher relational degrees were observed between HC emissions and aromatics or olefin contents, highlighting the need for lowering aromatics and olefin contents, thus reducing HC emissions.