China has been suffering severe air pollution caused by ozone (O₃) and secondary aerosols, which increasingly and severely threatens human health and ecological systems. To efficiently reduce the concentrations of these secondary pollutants, it is necessary to understand the relationship between these compounds and the precursors. In this study, the Community Multi-scale Air Quality (CMAQ) model was applied to simulate the temporal and spatial distribution of ozone and fine particulate matters (PM_2.5) as well as the major components over the Yangtze River Delta (YRD) in July 2017. We explores the impacts of different precursors on the formation of secondary pollution by setting up a series of emission reduction scenarios. Generally, ozone presents a positive sensitivity to biogenic volatile organic compounds (BVOCs), anthropogenic VOCs (AVOCs), and NO_X emissions in most of the region. The decreases in ozone concentrations caused by NOx reduction are about three times of VOC reduction. We also quantify the respective effects of NO_X and VOC emission reductions on radicals, which in most cases are opposite. For OH and NO₃ radicals, the reduction of VOC makes the concentration increase, while the reduction of NOx makes the concentration decrease. The impacts on HO₂ and RO₂ radicals are the opposite. For SOA, the sensitivity of biogenic originated SOA (BSOA) to BVOCs is higher than that of anthropogenic originated SOA (ASOA) to AVOCs. The sensitivity of ASOA to BVOCs is higher than that of BSOA to AVOCs.

Atmospheric oxidation; Ozone; SOA