Ozone: Science & Engineering, 33: 80–89 Copyright © 2011 International Ozone Association ISSN: 0191-9512 print / 1547-6545 online DOI: 10.1080/01919512.2011.536741 Air Quality Monitoring Network Design to Control Nitrogen Dioxide and Ozone, Applied in Granada, Spain Antonio Lozano, 1 José Usero, 2 Eva Vanderlinden, 2 Juan Raez, 1 Juan Contreras, 3 Benito Navarrete, 2 and Hicham El Bakouri 2 1 The Environmental Management Company (EGMASA), 41092, Seville, Spain 2 Department of Chemical and Environmental Engineering, University of Seville, 41092, Seville, Spain 3 Environmental Council of the Junta de Andalucía, 41071, Seville, Spain This paper describes a method to design air quality monitor- ing networks for nitrogen dioxide and ozone and its application in Granada, a city located in Andalusia, southern Spain. The city has a population of 236,988 inhabitants, and traffic is its main source of air pollution. Sampling campaigns with passive diffusion samplers at 88 sites were carried out to obtain information on the pollution distribution in Granada. The average concentrations found for NO 2 and O 3 were 36.5 μg/m 3 and 51.6 μg/m 3 , respectively. Maximum values of up to 57.1 μg/m 3 NO 2 were found in Granada city cen- ter and O 3 reached 77.2 μg/m 3 downwind from the emission source. After spatial interpolation of the obtained values with Geographical Information Systems, a selection of the best locations for the monitor- ing stations was made, in line with the macro- and microscale siting requirements of the European Directive 2008/50/EC on ambient air quality and cleaner air for Europe. Another sampling campaign with diffusive samplers was carried out in 2007 to determine if the loca- tions of the air quality assessment stations were still representative for their zone. A correction was made in the control network following results of this verification campaign. Keywords Ozone, Air Quality, Monitoring, Passive Sampling, Nitrogen Dioxide, Granada INTRODUCTION To obtain objective, reliable and comparable information on the air quality of a specific area, air quality monitoring networks are used, making it possible to take the requisite measures to protect the environment, to assess the results of such measures and to ensure that the public is properly informed about the state of the environment. The approval and publication of Council Directive 1996/ 62/EC (EEC, 1996) on ambient air quality assessment and Received 10/19/2009; Accepted 7/23/2010 Address correspondence to Hicham El Bakouri, Department of Chemical and Environmental Engineering, University of Seville, 41092 Seville, Spain. E-mail: elbakouri@us.es management and its daughter directives, 1999/30/EC (EEC, 1999), 2000/69/EC (EEC, 2000), 2002/3/EC (EEC, 2002) and 2004/107/EC (EEC, 2005), gave rise to an important change in air quality monitoring systems in Europe. Recently, in the interests of clarity, simplification and administrative efficiency, the above-mentioned European directives were replaced by the single Directive 2008/50/EC (EEC, 2008) on ambient air quality and cleaner air for Europe with no change to existing air quality objectives for nitrogen dioxide (NO 2 ) and ozone (O 3 ). With the aim of being as up-to-date as possible, references to the law will be made to Directive 2008/50/EC (EEC, 2008). The objective of this work was to develop a method to design or adjust air quality networks for monitoring nitro- gen dioxide and ozone in compliance with the legislation and to apply it in Granada. The proposed method consists of four steps for choosing the best locations for the monitoring stations in accordance with the legislation: (1) Preliminary evaluation; (2) Sampling campaigns with passive diffusion samplers; (3) Spatial interpolation; and, (4) Selection of best locations for the monitoring stations. The first step in the design process is the preliminary eval- uation of air quality based on historical data, which makes it possible to establish the minimum number and characteristics of the stations needed in each zone as set forth in Directive 2008/50/EC (EEC, 2008). The location of the monitoring stations depends on the distribution of the contamination lev- els of pollutants, as the stations need to record representative levels for the entire zone. The second step consists of sam- pling campaigns. In this research, sampling campaigns with a large number of diffusive samplers were used to deter- mine the concentration of nitrogen dioxide and ozone in the studied area. In a diffusion sampler, the gas molecules are trans- ported only by molecular diffusion, which is a function of 80 A. Lozano et al. January–February 2011