PM2.5 Concentration Gap Reduction between Typical Urban and Nonurban China from 2000 to 2023

Since 2013, stringent clean air initiatives have significantly reduced atmospheric pollutant emissions in China, improving air quality and altering the spatiotemporal patterns of pollution. Utilizing fine particulate matter (PM_2.5) and its chemical composition data from 2000 to 2023, we observed a reduction in the disparity of PM_2.5 concentrations between urban and nonurban areas. This reduction is linked to stricter emission controls in urban areas and the relocation of some emission sources to nonurban areas. However, the specific chemical constituents of PM_2.5 and the driving factors behind these changes remain to be fully elucidated. By analyzing the proportions of PM_2.5 components in major cities such as Beijing, Shanghai, and Guangzhou and their surrounding nonurban areas, we found that the narrowing gap in PM_2.5 concentrations between urban and nonurban regions is associated with the convergence of the organic matter (OM) proportions in both areas. This convergence results from varying emission reduction strategies tailored to the distinct characteristics of urban and nonurban pollution sources in China. Coordinated governance between urban and nonurban areas should be considered, along with the implementation of integrated control and mitigation measures for multiple pollutants, while paying attention to the different impacts of climate change on urban and nonurban regions, to further improve air quality in China.