Research on air quality collaborative control optimization scheme under the background of carbon peak

The coordinated control of PM_2.5 and O₃ is a critical mission for China and depends on scientifically designed precursor reduction strategies across regions. This study integrates source apportionment, precursor co-reduction scenarios, and functional response fitting to quantify how reductions in multiple precursors affect PM_2.5 components and O₃. Building upon that, a multi-objective optimization model was developed to determine the minimal coordinated precursor reduction strategies for the Beijing-Tianjin-Hebei (BTH) region in 2030 and 2035. Results show that primary particles (PP) and sulfate-nitrate-ammonium (SNA) have stronger local contributions than secondary organic aerosol (SOA) and O₃, and that mitigating secondary pollution requires enhanced inter-city collaboration, particularly among southern BTH cities. Reductions in SNA and SOA rely mainly on NOx and VOCs emission reductions, respectively, while O₃ formation is predominantly VOC-controlled or jointly controlled by NOx and VOCs. City-level analyses identify VOC-limited, NOx-limited, and transitional O₃ formation regimes, with optimal NOx/VOCs reduction ratios of 1:1.5-1:3, 1.5:1-3:1, and 1:1.5-1.5:1, respectively. The optimized strategies effectively meet concentration targets, driven by deep and scientifically reductions in NOx and VOCs. The validated nonlinear response characterization and collaborative optimization framework provides strategic support for coordinated PM_2.5-O₃ control in BTH and methodological guidance for regional air-quality policymaking elsewhere.