Characteristics of urban areas, such as density and compactness, are associated
with local air pollution concentrations. The potential for altering air pollution through
changing urban characteristics, however, is less certain, especially for expanding cities
within the developing world. We examined changes in urban characteristics from 2000 to
2010 for 830 cities in East Asia to evaluate associations with changes in nitrogen dioxide
(NO2) and fine particulate matter (PM2.5) air pollution. Urban
areas were stratified by population size into small (100,000–250,000), medium,
(250,000–1,000,000) and large (>1,000,000). Multivariate regression models
including urban baseline characteristics, meteorological variables, and change in urban
characteristics explained 37%, 49%, and 54% of the change in
NO2 and 29%, 34%, and 37% of the change in
PM2.5 for small, medium and large cities, respectively. Change in lights at
night strongly predicted change in NO2 and PM2.5, while urban area
expansion was strongly associated with NO2 but not PM2.5. Important
differences between changes in urban characteristics and pollutant levels were observed by
city size, especially NO2. Overall, changes in urban characteristics had a
greater impact on NO2 and PM2.5 change than baseline
characteristics, suggesting urban design and land use policies can have substantial
impacts on local air pollution levels.