Spatial Spillover and Differential Impacts of Urban Shrinkage on Air Pollutants: Implications for Sustainable Urban Futures

Abstract Rapid urbanization has historically been linked to escalating air pollution, yet the environmental consequences of urban shrinkage—a growing global trend of population decline and economic downturn—remain underexplored. While theory suggests shrinkage might alleviate pollution through reduced anthropogenic activities, empirical evidence on the complex, multi‐pollutant dynamics remains limited. To address this gap, we quantified the impact of urban shrinkage on the growth rates of six major air pollutants (PM 2.5 , PM 10 , SO 2 , O 3 , NO 2 , and CO) across 280 Chinese cities (2013–2022) using a Spatial Durbin Model integrated with satellite and socioeconomic data. Our results reveal an asymmetric environmental response to shrinkage. Demographic decline acts as a passive restoration mechanism for primary pollutants, reducing the growth rates of PM 2.5 and PM 10 by 10.5% and 16.0%, respectively, accounting for over one‐fifth of the total particulate reduction in these regions. Conversely, a structural trade‐off emerged: shrinkage accelerated regional NO 2 reductions (−9.0%) but contributed to a substantial surge in O3 concentrations (+25.4%), likely driven by altered chemical regimes. Crucially, we detect strong positive spatial spillovers, indicating that shrinking cities export air quality benefits to adjacent regions. These findings challenge growth‐oriented environmental planning, offering critical insights for regional air quality governance and fostering regional coordination in the era of global demographic transition.