Atmospheric Environment 38 (2004) 3809–3815 Assessment of urban air quality in Istanbul using fuzzy synthetic evaluation Guleda Onkal-Engin*, Ibrahim Demir, Halil Hiz Department of Environmental Engineering, Gebze Institute of Technology, Gebze 41400, Kocaeli, Turkey Received 13 November 2003; received in revised form 8 March 2004; accepted 30 March 2004 Abstract Little attention was paid to growing air quality concerns until about a decade earlier in Istanbul. With a population of over 12 million people and some occurred episodes imposed threats to the local government, and continuous monitoring of the urban air quality was started about a decade ago. This is part of a national strategy program which includes urban air quality assessment. This paper addresses a methodology for urban air quality using fuzzy synthetic evaluation techniques. The European part of Istanbul was selected for this purpose. Air pollutants data such as sulphur dioxide (SO 2 ), carbon monoxide (CO), nitrogen dioxide (NO 2 ), ozone (O 3 ), and total suspended particulate matter (PM) collected at five different air quality monitoring stations located in western part of Istanbul was used in this evaluation. The results obtained were compared to those applied to EPA air quality index. It was demonstrated that fuzzy synthetic evaluation techniques are quite appropriate techniques for air quality management. A case study was presented for this purpose. r 2004 Elsevier Ltd. All rights reserved. Keywords: Fuzzy synthetic evaluation; Air quality index; Fuzzy similarity method; Simple fuzzy classification; Fuzzy comprehensive assessment 1. Introduction Many industrialized and developing cities suffer from bad air quality for most part of the year. The air pollution comes mainly from land transportation, industrial emissions, and anthropogenic activities. Among them, land transportation contributes the most to the air pollution in the case of Istanbul. In most cases, national air quality goals are determined as targets. However, authorities have to take various parameters into account for air quality management (AQM), which makes the process complex. AQM involves three main phases, namely; monitor- ing, analyzing and reporting. The objectives of air quality monitoring, one of the most important phases of AQM, were listed by Demerjian (2000) as, to provide a database for determining air quality in major metropo- litan areas, to observe pollution trends in urban and non-urban areas, to assess compliance or progress made towards meeting air quality standards and to provide data for implementation of emergency control plans in the prevention of air pollution episodes. Therefore, in order to maintain a systematic long-term AQM approach, reliable assessment methods are needed. One should be able to measure the pollutants, predict the impact of the pollutant on air quality and decide the levels acceptable for human health. Here, choosing a proper classification method is an important issue. Differences in decision-making process of AQM arise from the lack of clear distinctions in the boundaries of standards. The purpose of classification is to group the air pollutant data into categories depending on the type of effect they can have on human health. In this process, ARTICLE IN PRESS AE International – Europe *Corresponding author. Fax: +90-262-754-2382. E-mail address: guleda@gyte.edu.tr (G. Onkal-Engin). 1352-2310/$-see front matter r 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.atmosenv.2004.03.058