Isoconcentration mapping of particulate matter in Hamedan intercity bus stations Edris Hoseinzadeh 1 , Mohammad Reza Samarghandi 2 , Farshid Ghorbani Shahna 3 & Ebrahim Chavoshi 4 1 Environmental Health Engineering, Department of Environmental Health Engineering, Faculty of Health, Lorestan University of Medical Sciences, Khorramabad, Iran; 2 Department of Environmental Health Engineering, School of Public Health, Centre for Health Research, Hamedan University of Medical Sciences, Hamadan, Iran; 3 Department of Occupational Health Engineering, School of Public Health, Centre for Health Research, Hamedan University of Medical Sciences, Hamadan, Iran; and 4 Department of Agricultural Machinery Engineering, Bu-Ali Sina University, Hamedan, Iran Keywords bus stations; Hamedan; isoconcentration; particulate matter. Correspondence Mohammad Reza Samarghandi, Department of Environmental Health Engineering, School of Public Health, Centre for Health Research, Hamedan University of Medical Sciences, P.O. Box 4171, Hamadan, Iran. Email: mrsamarghandi@umsha.ac.ir doi:10.1111/j.1747-6593.2012.00351.x Abstract To accomplish this study, the total concentration of suspended particles, PM10 and PM2.5, was mapped at intercity bus stations in the central square of Hamedan. To measure the particulate matter (PM), portable air sampling systems that collect integrated filter samples were used. The PM concentration was collected at various time intervals and measured gravimetrically. The results were then analysed using the ArcView GIS 3.3 software to map the particulate dispersion patterns. The mean concentrations of the total suspended particles (TSP), PM10 and PM2.5 were 1220.94  1418.5, 524.7  217.5 and 386  193.6 mg/m 3 , which were 16, 7.72 and 4.7 times greater than the World Health Organization (WHO) air quality stand- ard, respectively. The PM concentration was not correlated with wind velocity or air temperature, but was correlated with humidity (P = 0.01). Overall, the results of this pilot study indicate that people at bus stations are exposed to respirable particulate matter (RPM) at levels high enough to pose a serious health risk. Introduction In Hamedan, western Iran, many people use buses on a daily basis to enter the city. Accordingly, they spend a consider- able amount of time waiting at intercity bus stations, where they may be exposed to air pollutants, such as respirable particulate matter (RPM). Exposure to these pollutants may pose a health hazard to passengers, station staff and workers around the station (Cacciola et al. 2002; Bull 2008; Athar et al. 2010; Hess et al. 2010; Panis et al. 2010; Sternberg et al. 2010). Imam Square, which is the main square in Hamedan, is located in the city centre. The square is bor- dered by six normal 30-m wide streets that radiate at 60° angles (Fig. 1). Imam Square is typical of squares found throughout Iran. These squares are characterised by a high degree of economic activities and transportation by various vehicles, especially intercity buses. Imam Square has an area of more than 2 ha and a radius of 80 m. The streets surround- ing the square are very crowded, with more than 150 000 passengers passing through the area daily. The bus stations for travelling to any place of the city there is in these streets. The link between death rate and particulate air pollution has been extensively studied, but most of these studies have been limited by poor control of confounding factors. Some studies have connected cancer and cardiopulmonary disease to air pollutants, particularly fine particulate matter (PM 2.5) (Dockery 1993; Pope et al. 2002; Schins et al. 2004; Beelen et al. 2009). Epidemiological studies of the harmful human effects of air pollutants have also been reported (Lebowitz 1996; Preutthipan et al. 2004; Agarwal et al. 2006; Analitis et al. 2006). No studies of RPM at bus stations have been conducted in Iran to date. However, previous studies have suggested that exposure to various concentrations of RPM can pose a risk to the health of passengers (Khan et al. 2012). In Hamedan, the majority of buses in the transportation system use gasoline as fuel. Indeed, when we conducted this study, 200 sets out of 224 buses were using gasoline. Accordingly, a high level of suspended particles is expected at intercity bus stations. Therefore, in this study, an attempt to provide isoconcentra- tion mapping of suspended particles at bus stations using ArcView GIS 3.3 software (Environmental Systems Research Institute, Inc., Redlands, CA, USA) was made. Materials and methods This study was conducted for PM concentration evaluation in the bus stations in 2010. Sampling was conducted on all days Water and Environment Journal. Print ISSN 1747-6585 1 Water and Environment Journal •• (2012) ••–•• © 2012 CIWEM.