How does road accessibility increase air pollution in the Yangtze River Delta Region, China ?-Evidence from digital elevation model and points-of-interest data

Empirical evidences on how urban road accessibility affects air pollution is scarce for the specific Yangtze River Delta (YRD) region that is characterised by high density in economic activities and rapid urban expansion. Using novel Digital Elevation Model (DEM), road network and points-of-interest (POI) datasets to measure road accessibility, moderating and mediating effect models then were conducted to explore direct and indirect effects of road accessibility on environmental externality expressed by air pollution through urban connection and urban agglomeration. When exploiting exogenous variable in urban populations, the result of moderating effect model shows that road accessibility decreases air quality-to-connection elasticity by around -5.2% which indicates that road accessibility increases air pollution through internal connection. However, the finding of mediating effect model indicates that road accessibility slightly improves air quality through decreasing urban agglomeration. The findings of this paper suggest that high levels of road accessibility may have negative consequence for live-ability of YRD cities because of current urban internal connection and urban decision makers should consider the improvement of urban connection for obtaining better air quality.