The relationship between urbanization and air pollution affected by intercity factor mobility: A case of the Yangtze River Delta region

The rampant urbanization process has caused severe air pollution, particularly in the metropolitan areas with more concentrated and complicated human activities, which undermines urban sustainability. As cities are becoming increasingly interconnected (particularly in the urban agglomerations), cross-city factor mobility renders the response of air pollution to urbanization exhibit more complex and dynamic. Therefore, this paper attempts to embed spatial interaction effects of factor mobility into traditional "urbanization -air pollution" analytical framework to analyze the impacting mechanism of urbanization on air pollution. Taking the Yangtze River Delta region (YRDr) as an empirical case, we found: (1) Urbanization generally exerts a suppressing impact on air pollution in YRDr. Among the four sub-dimensions of urbanization, demographic urbanization tends to worsen air pollution, while the land, economic, and social urbanization have significant mitigating effects on air pollution. (2) Air pollution exhibits an inverted N-shaped change of "decrease -increase -decrease" as urbani-zation processes in YRDr. (3) Factor mobility including population, capital and industry tends to affect the relationship between urbanization and air pollution in varying ways. Accordingly, tailored strategies are rec-ommended to ensure more sustainable urbanization and higher air quality.