Relationships between urban form and air quality at different spatial scales: A case study from northern China

Abstract Examining the relationships between urban form and air quality on small spatial scales across multiple cities could simultaneously identify between- and within-city impacts. The current study used linear regression and geographically weighted regression models to identify the overall and local relationships between urban form and air quality at the city administrative unit, and at 50 km and 10 km spatial scales in 50 prefecture-level cities in northern China. Air quality data were obtained from 235 monitoring stations throughout 2015. Urban form was characterized by urban fragmentation, sparseness, continuity and forest area ratio, as computed from satellite images. High urban continuity and low forest area ratios were related to poor air quality at all three spatial scales. Urban sparseness had a positive relationship with air quality at the city administrative unit scale and a negligible relationship at the 50 km- and 10 km- scales. The overall relationship between urban form and air quality varied little according to spatial scale, while local relationships varied widely, with the difference increasing with decreasing scale. The findings suggest that, in general, public policy should encourage scattered, polycentric, and highly forested urban forms; however, policies for small spatial units within a city should consider the specific conditions of the unit.