The Impact of Industrial Clustering on Air Pollution in the Beijing–Tianjin–Hebei Urban Agglomeration: The Mechanism of Technological Innovation

As one of China’s most important industrial clusters, the Beijing–Tianjin–Hebei (BTH) urban agglomeration faces persistent air pollution while remaining a key driver of regional economic growth. In recent years, technological innovation has increasingly supported industrial upgrading and environmental improvement. The key research problem is therefore whether and under what conditions industrial clustering contributes to air pollution, and whether technological innovation can alter this relationship. To address this problem, this study uses panel data from 13 cities in the Beijing–Tianjin–Hebei region from 2015 to 2022 and employs Spatial Durbin Models, Spatial Threshold Models and sector-specific Spatial Durbin Models to examine how industrial clustering affects air pollution and how technological innovation moderates this relationship. The results indicate that (1) industrial clustering and air pollution exhibit an inverted U-shaped relationship, while the role of technological innovation varies across different stages of clustering; (2) technological innovation is associated with lower PM2.5 concentrations, and the positive association between industrial clustering and air pollution becomes weaker at higher levels of technological innovation, with the estimated threshold providing an exploratory division between innovation regimes; (3) the environmental associations between industrial clustering and pollution differ substantially across industrial sectors, reflecting clear sector-specific heterogeneity. Based on these findings, environmental policies in the BTH urban agglomeration should reflect differences in industrial structure and development stages. Technological innovation, industrial upgrading and differentiated emission-reduction measures across industries and cities may help mitigate the environmental costs of clustering while supporting sustainable development.