[Evaluation of the Synergistic Effects of Air Pollutant and Carbon Emission Reduction Strategies in Xi'an's Road Traffic].

Abstract

Based on the long-range energy alternative planning system （LEAP）， a carbon and pollutant emission model for Xi'an's road traffic from 2022 to 2050 was constructed， which incorporates both direct and indirect emissions. The model estimated the carbon and pollutant emission reductions under different scenario measures， and the synergistic emission reduction effects of each scenario were evaluated using the emission reduction elasticity coefficient （ELS） method. The scenario settings include seven single-measure scenarios， one comprehensive measure scenario （SA）， and an additional combined measure scenario （CS） specifically designed for the regulation of new energy vehicles. The results show that all single measures exhibited positive synergistic control effects. Among them， the co-benefit of CO₂e-PM_2.5 was the most significant， followed by that of CO₂e-CO. However， the intensity of CO₂e reduction was generally higher than that of NO_x and VOC. Specifically， the scenario of technology improvement for fuel vehicles （S6） had excellent pollution and carbon reduction capabilities； the scenario of low-carbon travel （S1） stood out in carbon reduction； the scenario of road-to-rail shift for freight transport （S2） significantly cut NO_x emissions； and the scenario of low vehicle saturation （S7） notably reduced VOC， PM_2.5， and CO emissions. Single measures for new energy vehicles have limited pollution and carbon reduction effects， and comprehensive management measures are needed to further unleash their emission reduction benefits. The CS scenario showed significant co-benefits for CO₂e-PM_2.5 and CO₂e-CO； its NO_x reduction effect was weaker than that of CO₂e， while its VOC reduction was stronger. The SA scenario demonstrated the most remarkable emission reduction potential， with annual CO₂e emissions decreasing by 1.22%； NO_x emissions ultimately reduced by nearly 50%； and VOC， PM_2.5， and CO emissions reduced by over 70%. Its ELS values generally fluctuated around 1， indicating that the scenario setting was reasonable， and synergistic control of carbon and pollution had been achieved. Additionally， the rebound of NO_x emissions in the later stage of the SA scenario highlights insufficient control over diesel trucks by existing measures. Future efforts should focus on in-depth emission reductions through multiple approaches like refined supervision， post-treatment technology improvement， and clean energy transition.