PM2.5-O3 Causal Relationship and Influencing Factors Analysis in Beijing-Tianjin-Hebei Region of China, 2015-2024 Based on Convergent Cross-Mapping Methods

Abstract In order to understand the relationship between PM2.5 and O3 interactions and the influencing factors in the Beijing-Tianjin-Hebei region, this paper analyses the air quality data of 13 cities in the Beijing-Tianjin-Hebei region in the past 10 years (2015–2024) using the Convergent Cross Mapping (CCM) method. The results show that the dynamic system of PM2.5 and O3 concentrations in the cities in the Beijing-Tianjin-Hebei region has obvious nonlinear and weak coupling characteristics. At the significance level of 0.1, most of the cities in the Beijing-Tianjin-Hebei region showed significant unidirectional or bidirectional causal relationships between PM2.5 and O3 concentrations in all seasons, and the results of the CCM test showed that the causal relationships and correlations between PM2.5 and O3 concentrations were influenced by meteorological factors, weather phenomena, human activities, regional transport, and the interaction mechanism between the two, and the seasonal variations were significant: the lowest number in spring, the highest in winter, and the lowest correlation in spring, the highest in winter and autumn; the number and correlation of causality peak in autumn and winter when PM2.5 concentration is higher; and the two pollutants have different causality in different seasons in some cities.