Potential heterogeneity in the relationship between urbanization and air pollution, from the perspective of urban agglomeration

Abstract

Different socioeconomic developments have substantially shaped the unique characters of cities in urban agglomerations, which may have led to uncertainties in the interpretations of the relationship between urbanization and environmental risks. This study chose the Beijing-Tianjin-Hebei (BTH) urban agglomeration region as a case study area, in order to explore the potential heterogeneity in the driving forces of the urbanization process for air pollution risk, based on ground-level fine particulate matter (PM2.5) monitoring data and socioeconomic panel data for the period 2014–2018. The pairwise analysis results confirmed that the urbanization process has significantly contributed to alleviating PM2.5 pollution in the BTH region. However, we found that there were contradictory pairwise-relationship curves related to the classical Environmental Kuznets Curve (EKC) hypothesis between the agglomeration and urban scales. Multivariate analysis further deepened the recognition of this heterogeneity, showing significant contribution differences in the socioeconomic factors for the variations in PM2.5 pollution among the 13 cities in the BTH region. We discussed our results in depth to enhance the understanding of the relationship between urbanization and air pollution in urban agglomerations. The significance of this study is the emphasis placed on the driving heterogeneity of socioeconomic factors for PM2.5 pollution within urban agglomerations. In the future, cross-scale studies on the heterogeneity of results from an imbalanced urbanization process will be helpful for better understanding the interaction between urban development and environmental stresses.