Evaluation of motor-vehicle emission control strategies for urban agglomeration of the Guanzhong region, China

Understanding emission trends and evaluating motor-vehicle emission control strategies (MVECSs) are essential for promoting sustainable transportation. In this study, city-level emission inventories for the Guanzhong urban agglomeration (GUA) were developed using the COPERT model. On this basis, MVECSs were evaluated from two perspectives: emission levels and emission efficiency. Furthermore, the emission reduction potential of motor vehicles across cities in the GUA was quantitatively assessed. The results show that PM_2.5, CO₂ and NO_X emissions from motor vehicles in the GUA showed an increasing trend, while VOC and SO₂ emissions decreased. Variations in emission levels were strongly influenced by vehicle types, with heavy-duty trucks (HDTs) identified as the primary contributors to CO₂, NO_X, PM_2.5, and SO₂ emissions, while motorcycles (MCs) dominated CO and VOC. Emissions evaluation analysis indicated that PM_2.5, CO, NO_X, and VOC were similarly responsive to control strategies. Efficiency analysis reveals that the comprehensive environmental efficiency of the GUA was 0.743, highlighting significant potential for emission reductions. In Xi’an, for example, the annual emission reduction potentials for CO₂, CO, and NO_X are 9.23 Mt, 22.7, and 27.5 kt, respectively. Finally, this study proposes targeted strategies for coordinated emission control and integrated multi-pollutant management.