Optimizing emission control strategies for mitigating PM2.5 and O3 pollution: A case study in the Yangtze River Delta region of eastern China

Effective mitigation of fine particulate matter (PM2.5) and ozone (O3) pollution necessitates collaborative regional emission control of major pollutants. In this study, we propose an approach based on source-receptor relationships (SRRs) and a mathematical programming (MP) model to quantify the regional atmospheric environmental capacity (AEC) constrained by certain air quality goals for PM2.5 and O3. We apply this method to optimize emission control strategies addressing a springtime case of concurrent high PM2.5 and O3 pollution in the Yangtze River Delta (YRD) region of eastern China in May 2014. Our analysis of SRRs reveals that O3 pollution is more contributed by regional transport compared to PM2.5, thereby limiting the potential for meeting the O3 target through anthropogenic emission reductions. Imposing various constraints on air quality goals and upper limits of emission reduction ratios yields significant variations in potential control pathways specific to source sectors and regions. To effectively mitigate PM2.5 pollution, substantial reductions in sulfur dioxide (SO2) and primary PM2.5 emissions are required, whereas ammonia (NH3) control demonstrates less effectiveness. Differentiated and coordinated efforts in controlling nitrogen oxide (NOx) and volatile organic compounds (VOCs) emissions are necessary to simultaneously achieve the desired PM2.5 and O3 targets. Evaluation of potential control pathways further emphasizes the effectiveness of implementing control measures on major precursor emissions to reduce PM2.5. However, meeting the O3 target remains challenging due to the complex nonlinearity involved in O3 formation. To attain the air quality goals for PM2.5 (<50 μg m−3) and daily maximum 1-h average (MDA1) O3 (<160 μg m−3) across the entire YRD, the estimated AEC values for SO2, NOx, NH3, VOCs, and primary PM2.5 are approximately 8.3, 79.4, 102.7, 186.9, and 13.0 kt mon−1, respectively, with corresponding emission reduction ratios of 95.6%, 75.5%, 33.1%, 45.1%, and 85.5% at the regional level.