Atmospheric concentrations of polycyclic aromatic hydrocarbons and selected nitrated derivatives in Greater Cairo, Egypt Hossam F. Nassar a, b, * , Ning Tang a , Takayuki Kameda a , Akira Toriba a , Mamdouh I. Khoder b, c , Kazuichi Hayakawa a a Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan b Environmental Research Division, National Research Center, El Dokki, Cairo, Egypt c Meteorology, Environment and Agriculture Faculty, King Abdulaziz University, Jeddah, Saudi Arabia article info Article history: Received 11 February 2011 Received in revised form 22 July 2011 Accepted 24 July 2011 Keywords: Polycyclic aromatic hydrocarbon Nitrated polycyclic aromatic hydrocarbon Greater Cairo Solid phase matter Atmosphere abstract Polycyclic aromatic hydrocarbons (PAHs) and selected nitrated derivatives (NPAHs) in air were deter- mined at two sites, El Dokki (a traffic site) and El Teppen (an industrial site) in Greater Cairo, Egypt, during the winter and summer seasons. The sites were selected to represent areas with different activities of Greater Cairo. The concentrations of fifteen PAHs having two to six rings were determined by using HPLC with florescence detection, while the concentrations of two NPAHs, 1-nitropyrene (1-NP) and 6-nitrocrysene (6-NC), were determined using HPLC with chemilumencence detection. Both the PAH and NPAH concentrations in El Teppen were higher than those in El Dokki. The total average concentrations of the fifteen PAHs over the investigated sites were 45.98 pmol m 3 in El Dokki and 77.01 pmol m 3 in El Teppen. All PAH and NPAH concentrations were higher in winter than in summer. The total average concentration of PAHs ranged from 21.9 pmol m 3 in summer to 63.74 pmol m 3 in winter. PAHs having four to six rings were the predominant compounds in particulate matters. The total average concen- trations of the two NPAHs (1-NP and 6-NC) were 30.2 and 12.4 fmol m 3 , respectively, in El Dokki, and 39.5 and 15.6 fmol m 3 respectively, in El Teppen. The total average concentrations of 1-NP and 6-NC were 36.99 and 15.43 fmol m 3 , respectively, in winter, and 29.76 and 10.56 fmol m 3 , respectively, in summer. These concentrations were compared with those of several cities in Asia that have been undergoing rapid economic and industrial development. The major sources and secondary reactions of PAHs and NPAHs were estimated based on the [NPAH]/[PAH] and [PAH]/SPM ratios. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Polycyclic aromatic hydrocarbons (PAHs) and their nitrated derivatives (NPAHs) are ubiquitous organic pollutants in the envi- ronment showing carcinogenic and/or mutagenic health effects (Ames et al., 1975; Epstein et al., 1979). PAHs and NPAHs mainly originate from the imperfect combustion of organic materials such as petroleum and coal. PAHs with four or more rings and NPAHs were detected in particulates exhausted from diesel and gasoline engine vehicles while PAHs having lower molecular weights were detected in both the gas phase in the atmosphere and unburned diesel fuel (Masclet et al., 1986). PAHs and NPAHs were also detected in smoke from steel and iron factories (Yang et al., 2002). Furthermore, several NPAHs are formed in the atmosphere via reactions of their parent PAHs with OH or NO radicals (Arey et al., 1986). The partitioning of semi volatile PAHs having no more than four rings between the particulate and the gas phase depends on various factors such as temperature and properties of the aerosol. However, five- and six-ring PAHs and three- to five-ring NPAHs are mostly associated with particulate matter (Bamford and Baker, 2003; Terzi and Samara, 2004). The amounts of the PAHs and NPAHs in the atmosphere depend on many factors such as their vapor pressures and concentrations, atmospheric pressure, temperature, and properties of dust (Keller and Terry, 1984). Concentrations of PAHs in street dust are assumed to be influenced by traffic density and rate of deposition (Ørseth and Ramdahl, 1985; Fang et al., 2004). Diesel vehicle exhaust and pavement were found to be major contributors of PAHs in road dust (Kirton and Crisp, 1990; Lee et al., 1998). Moreover, it has been revealed that there was a significant difference in the PAH profiles between locations rather than between size-fractions and sampling times (Marr et al., * Corresponding author. Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan. E-mail address: hossamnassar@yahoo.com (H.F. Nassar). Contents lists available at ScienceDirect Atmospheric Environment journal homepage: www.elsevier.com/locate/atmosenv 1352-2310/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.atmosenv.2011.07.043 Atmospheric Environment 45 (2011) 7352e7359