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h i g h l i g h t sVOCs, NO 2 , SO 2 and O 3 were measured around a densely populated industrial zone. Five separate weekly passive sampling campaigns were conducted at 55 locations. The spatial distribution of pollutants extracted in PMF were used to realize sources. Six factors were identified using a large number of chemical species available. The cancer risk due to benzene inhalation was calculated using Monte Carlo simulation. a r t i c l e i n f o a b s t r a c t Ambient concentrations of volatile organic compounds (VOCs), nitrogen dioxide (NO 2 ), sulphur dioxide (SO 2 ) and ground-level ozone (O 3 ) were measured at 55 locations around a densely populated industrial zone, hosting a petrochemical complex (Petkim), a petroleum refinery (Tupras), ship-dismantling facilities, several iron and steel plants, and a gas-fired power plant. Five passive sampling campaigns were performed covering summer and winter seasons of 2005 and 2007. Elevated concentrations of VOCs, NO 2 and SO 2 around the refinery, petrochemical complex and roads indicated that industrial activities and vehicular emissions are the main sources of these pollutants in the region. Ozone concentrations were low at the industrial zone and settlement areas, but high in rural stations downwind from these sources due to NO distillation. The United States Environmental Protection Agency's positive matrix factorization receptor model (EPA PMF) was employed to apportion ambient concentrations of VOCs into six factors, which were associated with emissions sources. Traffic was found to be highest contributor to measured P VOCs concentrations, followed by the Petkim and Tupras. Median cancer risk due to benzene inhalation calculated using a Monte Carlo simulation was approximately 4 per-one-million population, which exceeded the U.S. EPA benchmark of 1 per one million. Petkim, Tupras and traffic emissions were the major sources of cancer risk due to benzene inhalation in the Aliaga airshed. Relative contributions of these two source groups changes significantly from one location to another, demonstrating the limitation of determining source contributions and calculating health risk using data from one or two permanent stations in an industrial area.

Concentrations of 91 volatile organic compounds (VOCs) ranging from C5 to C12 were measured at three sites in Ankara, the capital of Turkey, in the summer of 2003 and winter of 2004. Samples were collected at roadside, residential and background stations at consecutive 4-hr intervals over a 24-hr period for six weeks in each season. Air samples were collected onto cartridges packed with Tenax TA and Carbopack B resins and analyzed by thermal desorption, followed by gas chromatography coupled to a mass selective detector (GC/MSD). Time resolved data provided information on ambient levels, temporal and spatial variations and sources of VOCs in Ankara. Toluene is the most abundant compound at all sites with and average concentration of 13.1 ?g m-3. The mean concentrations of benzene are 12.6, 5.2, and 2.4 ?g m-3 during winter at roadside, residential and background stations, respectively. Diurnal variation in the data together with toluene to benzene concentration ratio (T:B) that is close to 2.0 indicated the influence of traffic related emissions at residential and roadside stations during winter season. Higher T:B ratio observed at residential and background stations during summer period and correlation analysis indicated additional VOC sources. Temporal variations and low m,p-xylene to ethylbenzene ratio (mpX:E) indicated that transported air mass is the major VOC source influencing VOC concentrations measured at the background station.Implications: VOC measurement at three sites in Ankara, the capital of Turkey showed that VOC concentrations measured at the roadside station are reasonably higher than concentrations measured at residential and background sites. Diurnal variations of VOC concentrations revealed that traffic emissions at roadside and residential locations are a significant VOC source in Ankara. On the other hand, VOC levels measured at the background site are transported from more polluted parts of Ankara.