The Impact Mechanisms and Paths of the National Big Data Comprehensive Pilot Zones on Urban Pollution Reduction and Carbon Mitigation

The National Big Data Comprehensive Pilot Zone (NBDCPZ) constitutes a landmark institutional initiative designed to advance and deploy data elements while strengthening governance capacity for environmental sustainability and low-carbon transition. Drawing on a panel dataset covering 285 Chinese cities at or above the prefectural level over the 2005–2023 period, this study capitalizes on the sequential rollout of the NBDCPZ to establish a quasi-natural experimental design. It employs a staggered difference-in-differences (DID) design to examine the policy’s causal effects on urban environmental quality—specifically, its effectiveness in curbing air pollution and carbon emissions—and further identifies the underlying mechanisms driving these effects and sources of contextual heterogeneity. The results demonstrate that the policy yields substantial benefits in curbing urban pollution and advancing carbon reduction; this conclusion remains robust across multiple sensitivity checks. Mechanism analysis reveals that the policy achieves synergistic gains in pollution reduction and carbon mitigation by promoting green innovation and reducing energy consumption, as well as by fostering digital industry agglomeration and accelerating digital innovation. Heterogeneity analysis shows significant structural variation in policy effects: non-resource-based cities exhibit more pronounced carbon mitigation effects, whereas resource-based cities, large cities, and old industrial bases demonstrate stronger pollution control effects.