Quantifying Responses of Concurrent PM2.5-O3 Pollution to Their Precursors in the Yangtze River Delta Megacity Cluster of China

In recent years, ambient PM2.5 and O3 have emerged as major environmental concerns, making it crucial to elucidate their spatiotemporal patterns and driving factors. Accordingly, this study characterizes the spatiotemporal evolution and primary drivers of concurrent PM2.5–O3 pollution across the YRDMC, based on hourly observational data from 266 monitoring stations during 2015–2020. The yearly cumulative number of concurrent PM2.5–O3 threshold breaches indicates that joint pollution across the YRDMC declined by 22.28