Linking Urban Structure and Air Quality

Abstract

The degradation of urban air quality is an object of concern today, since a great part of the world population lives in urban areas. While the environmental implications of industrial and transport activities have been recognized for decades, the influence of the urban patterns in air quality is still poorly understood. Currently, urban areas are expanding towards rural ones which, together with the segregation of land uses related to daily activities (home, school, work, leisure), lead to an increase of motorized trips and trip distances, resulting in an increase of air pollutants emissions. This paper carries out the state of the art concerning the link between urban structure and air quality. This link is neither simple nor direct; currently there is a debate on which is the most sustainable urban form - the compact city or the dispersed city. Several empirical and modeling studies integrating land use, transport and air quality issues and its main conclusions are presented. Results indicate that compact cities promote a better air quality when compared to the dispersed cities. On the other hand, when the subject is human exposure to pollutants, compact cities present the worst results. These studies allow concluding about the influence of the city structure in air pollutants levels, highlighting the importance of air quality as a relevant urban planning indicator.