Causality and dynamic spillover effects of megacities on regional industrial pollution reduction

Regional economic power and local environmental policies have a substantial impact on pollution reduction in urban agglomerations (UAs); however, whether megacities in UAs exert spillover effects of pollution reduction on surrounding cities remains unknown. This study presents a causal analytic framework to evaluate the spillover effects of megacities on regional industrial pollution reduction in three major UAs in China between 2005 and 2016. The interaction between industrial pollution reduction and infrastructure investment indicators was also examined. Re-sults indicated a good fit for spatial spillover of sulfur dioxide reduction (SR) in the Pearl River Delta (PRD) and Yangtze River Delta (YRD) but not in the Beijing-Hebei-Tianjin cluster (JJJ). Spatial spillover of dust reduction (DR) was evident in the PRD and JJJ but not the YRD. Spatial analysis showed that infrastructure investment indicators, at megacity and UA levels, had short-term spillover effects on surrounding cities for DR but not SR. However, spatial spillover effects, at both the city and UA levels, were substantial over the long term. In addition, the results of the spatial-time lag analysis suggest a linear relationship between pollution control-related infra-structure investment indicators and long-term pollution reduction. This study provides new in-formation regarding the spatial spillover effects of megacities on regional industrial pollution reduction in UAs.

Automated summary

This study examines the spillover effects of megacities on regional industrial pollution reduction in urban agglomerations in China. The results show that infrastructure investment indicators at the megacity and urban agglomeration levels have short-term spillover effects on surrounding cities for dust reduction, but not for sulfur dioxide reduction. However, substantial spatial spillover effects were found over the long term at both the city and urban agglomeration levels.