Does the New-Type Urbanization Policy Help Reduce PM2.5 Pollution? Evidence from Chinese Counties

Traditional urbanization prioritizes economic growth but often degrades the environment, challenging SDGs 9 and 13. China’s New-Type Urbanization Policy (NTUP) balances economic expansion, energy conservation, and environmental protection. By applying the difference-in-differences (DID) method, this study examines the causal effect of NTUP on urban air quality, taking the full implementation of NTUP in 2014 and the designated pilot cities as the policy shock and treatment group, respectively. Furthermore, we explore the mediating roles of land use efficiency and innovation efficiency in this relationship. The results show the following: (1) NTUP significantly lowers urban PM2.5, robust to confounders and selection bias; (2) land use and innovation efficiency mediate this effect, verified by Sobel and Bootstrap tests; and (3) policy effectiveness varies by city level, industrial base, and economic structure. These findings highlight NTUP’s environmental benefits and inform sustainable urbanization strategies globally.