Can polycentric urban spatial structures reduce pollution aggregation?

• Explore how the polycentric urban spatial structure impacts pollution agglomeration. • Polycentric urban spatial structure can effectively reduce pollution concentration. Heterogeneity in population size, economic development and resource endowment is investigated. • Productive services agglomeration and capital factor market distortion play a mediating role. In response to the conflict between environmental management and economic and social progress, the Chinese government has launched a project to design a spatial framework for polycentric cities. However, the role of polycentric in influencing the environment remains controversial, and fewer studies are related to the mechanisms of their influence. Thus, the study sample for this paper consisted of 272 prefecture-level cities in China from 2006 to 2021. Urban polycentric and geographic concentration were calculated using the place-order scale approach to determine pollution agglomeration. Subsequently, polycentric influence on pollution agglomeration and the mechanisms that underpin it are investigated using two-way fixed-effects and mediated-effects models. The findings indicate that China’s pollution agglomeration levels shifted from “high in the east and low in the west” to “low in the east and high in the west” throughout the study period. Cities’ spatial structure is predominantly polycentric, and the polycentric tends to strengthen. The benchmark regression findings demonstrate that polycentric development is conducive to reducing pollution concentration. Heterogeneity shows that polycentric is more effective in reducing pollution in super-sized cities, cities with high economic development, and non-resource cities. According to the examination of mediation effects, increasing the agglomeration of productive services and reducing the distortion in capital factor markets are important paths for polycentric to improve their environment. These conclusions provide empirical evidence for understanding the relationship between urban spatial structure and pollution agglomeration, offering a theoretical basis for government to formulate urban spatial development plans.