Green Industry Agglomeration and Public Environmental Awareness: Dual Mechanisms Accelerating Green Development in Zero-Waste Cities

Zero-waste city (ZWC) construction serves as a vital approach to regional sustainable development amid tightening resource constraints and the dual carbon goals. Examining its impact on urban green development efficiency (UGDE) and the underlying transmission mechanisms bears important theoretical significance and practical value. Drawing on panel data covering 281 Chinese cities from 2008 to 2024, this study adopts the difference-in-differences model to examine how the zero-waste city pilot (ZWCP) policy affects UGDE. The main findings are summarized as follows. (1) ZWCP policy significantly improves UGDE, and this core conclusion remains robust after multiple robustness tests and endogeneity corrections. (2) Mechanism tests confirm that ZWCP elevates the green development efficiency of pilot cities through two intermediate channels: green industrial agglomeration and public environmental awareness. (3) The ZWCP policy exerts positive spatial spillover effects on UGDE improvement. However, the two transmission mechanisms show heterogeneous spatial linkage effects. Green industrial agglomeration acts as the core channel for policy spatial radiation, with inter-city agglomeration diffusion driving UGDE growth in neighboring cities. In contrast, public environmental awareness only exerts a local mediating effect, with no significant spatial spillover on UGDE. (4) The moderation analysis reveals that government environmental attention (GEA) strengthens both transmission paths, exerting a positive moderating effect on the UGDE promotion of ZWCP. (5) Heterogeneous results indicate that the policy’s boosting effect is more pronounced in eastern regions, resource-based cities and highly urbanized cities. These findings provide empirical evidence and targeted policy references for advancing urban green development efficiency via the differentiated implementation of zero-waste city initiatives across China. They also offer practical Chinese insights for other developing economies pursuing green urban transition.