How urban structure can affect city sustainability from an air quality perspective C. Borrego * , H. Martins, O. Tchepel, L. Salmim, A. Monteiro, A.I. Miranda Department of Environment and Planning, University of Aveiro, 3810-193 Aveiro, Portugal Received 12 August 2003; received in revised form 8 July 2004; accepted 12 July 2004 Available online 25 February 2005 Abstract Despite the progress made in controlling local air pollution, urban areas show increasing signs of environmental stress and air quality is one of the major concerns. The findings of several studies provide evidence that the shape of a city and the land use distribution determine the location of emission sources and the pattern of urban traffic, affecting urban air quality. This work focuses on the potential impacts of different land use patterns on urban air quality. Three imaginary cities were created, based on alternative urban planning strategies, considering different land use patterns: from the scenario of urban sprawl to the opposite scenario of a compact city with mixed land use. The mesoscale photochemical system MEMO/MARS was applied to evaluate the urban air quality in each of the idealized city structures. Simulation results indicate that more compact cities with mixed land use provide better urban air quality compared to disperse and network cities. Ó 2005 Elsevier Ltd. All rights reserved. Keywords: Urban air quality; City structure; Atmospheric modelling; Sustainable city 1. Introduction Europe is a highly urbanised continent with more than two thirds of the total population living in urban areas. Although emissions from motorized vehicles and large point sources have been reduced through the use of cleaner fuels and technology, urban areas still show increasing signs of environmental stress: loss of open space, traffic congestion, noise and air quality degrada- tion (Fenger et al., 1998). These persisting stresses show that technological improvements alone are unlikely to provide the solution. There is thus a need to rethink the current models of organization and urban development patterns. While the environmental implications of industrial discharges have been recognised for decades, the influence of urban patterns on the environment is still poorly understood (EEA, 2000). A recent study conducted by the US EPA (EPA, 2001) based on the application of regional models of development patterns and on empirical studies, concluded that a compact and mixed-use development could reduce vehicle travel and road traffic-related air pollution. The aim of the present study is to contribute to the understanding of how urban planning affects air quality. In order to achieve this, a photochemical modelling system has been applied to three idealized cities with different urban structures. 2. Methodology With the purpose of evaluating the potential impacts of different spatial structures on urban air quality, three * Corresponding author. Fax: C351 234 382 876. E-mail address: sec@idad.ua.pt (C. Borrego). 1364-8152/$ - see front matter Ó 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.envsoft.2004.07.009 www.elsevier.com/locate/envsoft Environmental Modelling & Software 21 (2006) 461–467