<p>This study investigates the environmental impacts of urban networks, a critical yet underexplored dimension of regional environmental governance. Focusing on China, it aims to dissect how industrial and technological spillovers transmitted through inter-city functional linkages affect urban air quality. To achieve this, I constructed an urban network of 284 Chinese cities using a comprehensive dataset of inter-city manufacturing investment flows from 2004 to 2018. Subsequently, a spatial Durbin model was employed to empirically examine the spillover effects on city-level PM2.5 concentrations. The results revealed a significant dual-spillover effect: industrial spillovers, driven by manufacturing investment, significantly exacerbate air pollution, consistent with a “pollution haven” effect. Conversely, technological spillovers flowing through the same network significantly improve air quality, indicating a “pollution halo” effect. Furthermore, these environmental impacts are heterogeneous, with the negative effects of industrial spillovers being substantially mitigated in cities with higher economic development, innovation capacity, and advanced industrial structures. A period-based analysis showed that the adverse impact of industrial spillovers diminished over time, while the positive influence of technological spillovers strengthened. These findings underscore the necessity of shifting from purely place-based environmental policies to a network-oriented governance framework. Such a framework should promote coordinated cross-regional industrial planning and technology-sharing policies to ensure that urban networks function as conduits for sustainable development rather than for pollution displacement, thereby mitigating regional environmental inequality.</p>