Detecting atmospheric oxidation in the PM2.5 and ozone multilayer complex network

Reducing the levels of Fine particulate matter (PM2.5) and ozone (O3) is essential for further improving air quality in China. The intricate and non-linear interactions between PM2.5 and O3 on a national scale over long-term records are not well understood. Here, we proposed a novel multi-layer network approach to bridge the gap. Our findings reveal that the variability of O3 precedes that of PM2.5 by one day. The degree, weighted degree, and edge distance follow a power-law decay distribution, suggesting that their relationship is not a random process. O3 concentration in the Yangtze River Delta (YRD) region and eastern Shandong Province significantly impacts the PM2.5 levels in surrounding areas. Conversely, PM2.5 concentrations in Shandong Province, Henan Province, YRD and Pearl River Delta (PRD) have a strong influence on O3 levels. Moreover, we quantified the seasonality of the interactions and elucidated the underlying reasons. The results revealed the interactions between PM2.5 and O3 are intricately tied to atmospheric oxidation processes. More specifically, in summer, the atmospheric oxidation has a strong impact on the interactions in key regions, such as the Beijing–Tianjin–Hebei,YRD region and Fenwei Plain. However, the PRD region experiences a more pronounced effect from atmospheric oxidation on this relationship in winter. These findings demonstrate that it is crucial to effectively regulate atmospheric oxidation to mitigate PM2.5 and O3. Our results also serve as a valuable methodological framework for understanding the characteristics of pollutants.