Can digital infrastructure construction promote the synergy between pollution and carbon reduction? A quasi-natural experiment based on the “Broadband China” pilot policy

Abstract Digital infrastructure (DI) presents a critical opportunity for China to address the dual challenges of climate change and environmental pollution. In this study, we empirically investigate the effects and mechanisms of DI on the synergy between pollution and carbon reduction (SPCR) using balanced panel data from 273 Chinese cities during 2011–2023. The results reveal that DI significantly reduces CO 2 and SO 2 emissions, thereby promoting SPCR. The mechanism analysis shows that DI facilitates synergistic governance by limiting the entry of heavily polluting enterprises and increasing government expenditure on environmental protection. Heterogeneity analysis suggests that the synergistic effects of DI are more pronounced in cities with small and medium size, high digital innovation capacity, advanced economic development, and greater government digital attention. This study clarifies the micro- and macro-mechanisms through which DI empowers cities to achieve SPCR, and provides empirical evidence and policy implications for improving DI construction and promoting urban green transformation.