The role of a steel plant in north-west Italy to the local air concentrations of PCDD/Fs Maurizio Onofrio, Roberta Spataro, Serena Botta ⇑ Department of Land, Environment and Geo-Engineering, Politecnico di Torino, C.so Duca degli Abruzzi, 24, 10129 Turin, Italy article info Article history: Received 20 July 2010 Received in revised form 19 October 2010 Accepted 31 October 2010 Available online 20 November 2010 Keywords: PCDD/Fs Air dispersion model Steel plant emissions Air monitoring PCA abstract Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are ubiquitous contaminants, mainly released into the environment during combustion processes (point sources), but also from other sources (traffic, uncontrolled combustion). This study aims at investigating the contribution of a steel plant in NW Italy (700 000 tons of steel year 1 ) to the air concentrations of PCDDs/PCDFs at local level, through the analysis of measured, modelled and literature data. The study was carried out in an area of 600 km 2 , using air quality data mea- sured by the institutional monitoring network, data obtained from AERMOD simulations and literature data. The measured air concentrations were consistent with literature values for similar areas, and both the homologue profiles and PCA analyses showed a clear distinction between the monitoring stations and the source profiles. All the previous results were confirmed by the air dispersion model (AERMOD), that predicted PCDD/F air concentrations due to the steel plant from four to two orders of magnitude lower than those measured in the monitoring stations, highlighting the presence of other sources. This study outlines the limited influence of the source in the local PCDD/F air concentrations and at the same time the usefulness of a joint analysis of measured, literature and calculated data to correctly eval- uate the role of a source to the local pollution. The study also highlights the usefulness of AERMOD as a complementary tool to define the correct placement of monitoring stations and to locate those areas expected to have the highest air concentrations deriving from a source. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are ubiquitous environmental contami- nants. Due to PCDD/F risks for human health and their natural abil- ity of bioaccumulate in the food chain (Welsch-Pausch and McLachlan, 1998; Isosaari et al., 2004; Zhao et al., 2006), many studies aimed at investigating PCDD/Fs behavior in different matri- ces (air concentration, deposition, soil concentration, etc.) have been carried out (Abad et al., 2004; Coutinho et al., 2007; Mari et al., 2008; Zhang et al., 2009). In particular, there are many available studies aimed at investi- gating different aspects of PCDD/F local air concentrations, such as: the influence of different types of industrial sources (mainly waste incinerators, steel mills, metal smelting and chlorination) (Bakoglu et al., 2005; Mari et al., 2008; Colombo et al., 2009; Li et al., 2010) and traffic (Benfenati et al., 1992; Chetwittayachan et al., 2002), atmospheric fate and transport (Lohman and Seigneur, 2001), deposition (Lohman and Seigneur, 2001; Bakoglu et al., 2005; Zhang et al., 2009), seasonal variability of their concentration and typical ambient air levels in urban, rural and industrial areas (Caserini et al., 2004; Cleverly et al., 2007; Menichini et al., 2007). The knowledge of all these aspects is necessary to correctly evaluate the role of different sources in the PCDD/F local air concentrations and consequently in population exposure. Large industrial plants are often considered responsible for the decline of air quality and, more or less directly, the onset of diseases asso- ciated with them, even in the absence of exhaustive environmental impact and risk assessments. Our research aims at investigating the contribution of a steel plant in NW Italy (700 000 tons of steel year 1 ) to the air concentrations of PCDD/PCDFs (in terms of 17 most toxic 2,3,7,8- substituted PCDD/F congeners) at a local level, through the analysis of measured, modelled and literature data. A 1 year survey was conducted in 2006 by the local Environmental Protection Agency (ARPA Piemonte) in five monitoring stations defined by the agency to determine population exposure in the vicinity of the steel plant. Simultaneously, an additional site was monitored in the same way, outside the area of influence of the source. This site was considered representative of background pollution. 0045-6535/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.chemosphere.2010.10.095 ⇑ Corresponding author. Tel.: +39 011 090 7717; fax: +39 011 090 7622. E-mail address: serena.botta@polito.it (S. Botta). Chemosphere 82 (2011) 708–717 Contents lists available at ScienceDirect Chemosphere journal homepage: www.elsevier.com/locate/chemosphere