An Analysis of the Synergistic Effects of Air Pollutant Reduction and Carbon Mitigation in Major Emission Reduction Policies in China’s Transportation Sector

As of 2023, China’s transportation energy carbon emissions account for over 10%, which has a significant impact on achieving “dual carbon” goals. China has successively issued various policies to address pollution emissions in the transportation industry. This study mainly analyzes the synergistic effects of pollution reduction and carbon reduction measures implemented in this industry. We selected 2023 as the base year, focused on promoting new energy vehicles (NEVs), advocating bus transit (ABT), and advancing rail transit (ART) as the three major emission reduction policies, and analyzed their synergistic effects on air pollutant control and greenhouse gas emission reduction. Based on national scale data on driving conditions, energy consumption, and emission factors, the synergistic emission reductions in greenhouse gases and air pollutants brought about by the three policies were first calculated. Then, using the coordinate system of synergistic control effects, cross elasticity analysis of pollutants, and normalization evaluation methods, the multi pollutant synergistic control capabilities of each policy were quantified. Quantitative results revealed that the NEV substitution policy achieved a CO2 reduction of 100.966 million tons in 2023, alongside reductions of 1.0196 million tons (CO), 59,506 tons (NOx), 103,500 tons (NMHC), 6266 tons (PM10), and 3071 tons (SO2). Based on the APeq ranking, its comprehensive benefits (APeq = 166,734.52) significantly outperform ART (APeq = 97,414.89) and ABT (APeq = 19,796.80). The main research conclusion shows that replacing private gasoline cars with new energy vehicles can have a synergistic emission reduction effect on all five types of air pollutants and greenhouse gases involved in this study, with a positive synergistic effect. Moreover, the policy development priority is relatively better based on the synergistic emission reduction equivalent. Both buses and rail transit have not brought about SO2 emission reduction, nor have they had a positive synergistic effect on SO2 and CO2 emission reduction. On this basis, buses also contribute to NOx emissions. For other air pollutants, both rail transit and buses can have a synergistic effect of reducing pollution and carbon emissions.