Impacts of reducing air pollutants and CO(2) emissions in urban road transport through 2035 in Chongqing, China

The road transport sector in megacities is confronted with pressing local air pollution and carbon dioxide (CO(2)) control issues. To determine effective policy instruments for saving energy and the co-control of air pollutants and CO(2), several mainstream measures were examined and compared in Chongqing's road transport sector from 2017 to 2035. An integration assessment framework was developed by combining the Long-range Energy Alternatives Planning (LEAP) system and a set of quantitative methods for evaluating the co-benefits of emission reductions (including the air pollutant equivalent (AP(eq)), co-control coordinate system, and pollutant reduction cross-elasticity (Els(a/b))). Results showed that the shifting transportation modes scenario presented the most significant potential for energy-saving and emission reductions, reducing energy use by 30.9% and air pollutants and CO(2) emissions by approximately 27–32% compared with the business as usual (BAU) scenario in 2035. The improving energy efficiency scenario also provided significant co-benefits for reducing air pollutants and CO(2) emissions. Nevertheless, the promoting alternative fuel scenario may increase fine particulate matter (PM(2.5)) emissions by 2.2% compared to BAU in 2035 under the cleanness of regional electricity in 2017. Our findings suggest that the shifting transportation modes were effective measures to reduce air pollutants and CO(2) in the short term synergistically, and highlighted the importance of cleaner electricity generation to develop electric vehicles in the medium and long term.