Characterization of particulate polycyclic aromatic hydrocarbons in the east of France urban areas

Background

Air samples collected on three different urban sites in East of France (Strasbourg, Besan?on, and Spicheren), from April 2006 to January 2007, were characterized to measure the concentrations of polycyclic aromatic hydrocarbons (PAHs) in the particulate phase (PM₁₀) and to examine their seasonal variation, diurnal variations, and emission sources.

Results

The average concentrations of ??PAHs were 12.6, 9.5, and 8.9?ng?m^?3 for the Strasbourg, Besan?on, and Spicheren sites, respectively. Strong seasonal variations of individual PAH concentrations were found at the three sampling sites, with higher levels in the winter that gradually decreased to the lowest levels in the summer. The diurnal variations of PAH concentrations in summer presented highest concentrations during the morning (04:00?C10:00) and the evening (16:00?C22:00) times, indicating the important contribution from vehicle emissions, in the three sampling sites. Furthermore, the ratio of BaP/BeP suggests that the photochemical degradation of PAHs can suppress their concentrations in the midday/afternoon (10:00?C16:00), time interval of highest global irradiance. In winter, concentrations of PAH were highest during the evening (16:00?C22:00) time, suggesting that domestic heating can potentially be an important source for particulate PAH, for the three sampling sites.

Conclusion

Diagnostic ratios were used to identify potential sources of PAHs. Results showed that vehicle emissions may be the major source of PAHs, especially in summer, with a prevalent contribution of diesel engines rather than gasoline engines at the three sites studied, independently of the seasons.     

Characterization and concentrations of polycyclic aromatic hydrocarbons in emissions from different heating systems in Damascus,Syria

Traffic has long been recognized as the major contributor to polycyclic aromatic hydrocarbon (PAH) emissions to the urban atmosphere. Stationary combustion sources, including residential space heating systems, are also a major contributor to PAH emissions. The aim of this study was to determine the profile and concentration of PAHs in stack flue gas emissions from different kinds of space heaters in order to increase the understanding of the scale of the PAH pollution problem caused by this source. This study set out to first assess the characteristics of PAHs and their corresponding benzo[a]pyrene equivalent emissions from a few types of domestic heaters and central heating systems to the urban atmosphere. The study, enabled for the first time, the characterization of PAHs in stationary combustion sources in the city of Damascus, Syria. Nine different types of heating systems were selected with respect to age, design, and type of fuel burned. The concentrations of 15 individual PAH compounds in the stack flue gas were determined in the extracts of the collected samples using high-performance liquid chromatography system (HPLC) equipped with ultraviolet–visible and fluorescence detectors. In general, older domestic wood stoves caused considerably higher PAH emissions than modern domestic heaters burning diesel oil. The average concentration of ΣPAH (sum of 15 compounds) in emissions from all types of studied heating systems ranged between 43?±?0.4 and 316?±?1.4 μg/m³. Values of total benzo[a]pyrene equivalent ranged between 0.61 and 15.41 μg/m³.     

Distribution and spatial trends of PAHs and PCBs in soils in the Seine River basin, France

Persistent organic pollutants (PAHs and PCBs) in soil samples from seven sites across the Seine basin were analysed. Samples were taken from industrialized, urban, suburban and remote sites. Results showed spatial differences, in terms of concentrations and congener profiles. PAH (Sigma14 PAHs) and PCB (Sigma 7 PCBs) concentrations ranged from 450 to 5650 microg kg(-1) and 0.09 to 150 microg kg(-1), respectively. A clear gradient from industrial to remote sites was highlighted, with a ratio of up to one order of magnitude for PAHs and two orders of magnitude for PCBs. Fluoranthene and pyrene were predominant, while the carcinogenic PAHs represented 15-46% of the total PAH content. Using hierarchical cluster analysis, soil samples profiles were compared and the influence of site location and potential sources were identified: automobile traffic, domestic heating, and industrial emissions were the prevalent PAHs sources in the Seine basin. PCB profiles suggested different transport patterns among congeners. For remote sites, the congener fingerprint showed a relatively higher proportion of the most volatile congeners, which were attributed to increased atmospheric residence times. Thus, PAH and PCB distributions in soils provided information on sources and evidence for short-range transport, and profiles of compounds reflected differences between regional and local emissions. This study demonstrates that soil sampling can be used to investigate spatial differences in atmospheric inputs of persistent organic pollutants based on differences in the mixtures of compounds, reflecting differences in regional and local atmospheric emissions.     

Sources and seasonal variation of atmospheric polycyclic aromatic hydrocarbons in Dalian,China: Factor analysis with non-negative constraints combined with local source fingerprints

Vapor- and particulate-phase polycyclic aromatic hydrocarbon (PAH) samples were continuously collected at an urban site in Dalian, China, during the heating and non-heating period. There is strong temperature dependence and obvious seasonal trend for atmospheric PAHs, and significant positive correlations of atmospheric PAHs with SO₂ and CO concentrations were observed. Factor analysis model with non-negative constraints (FA–NNC) combined with local and literature PAH source fingerprints was successful in source identification of particulate PAHs in the atmospheric samples. The results suggested that, in heating period, the main pollution sources were identified as coal-fired boiler emission (56%), residential coal combustion (33%) and traffic emissions (11%). As for non-heating period, the main sources were gasoline engine emission, traffic tunnel emission and coal-fired power plant, and the overall source contributions of traffic emission (gasoline engine + traffic tunnel) were 79% and coal-fired power plant 21%. The current results support our previous study and provide new insights. This can be the first attempt to quantitatively apportion air organic pollutants using receptor models combined with local source fingerprints. The source fingerprints can be used as reference data for source apportionment of atmospheric PAHs of China.     

Seasonal variation on size distribution and concentration of PAHs in Guangzhou city, China

Size distribution aerosol samples were collected at an urban location of Guangzhou in four seasons of 2003-2004 by a MOUDI (Micro-orifice Uniform Deposit Impactor). The particle loading (PM10: 80-397 microg m(-3)) was comparable with some other Asia cities; however, much higher than that of Western Europe and North America. Polycyclic aromatic hydrocarbons (PAHs) were measured by gas chromatography with mass selective detector (GC-MS). Seasonal effects on the size distribution of PAHs are presented. Bimode (accumulation and coarse mode) and unimode (accumulation mode) distributions were observed for low-molecule-weight and high-molecule-weight PAHs. A slight shift to larger particles was found for the accumulation mode in autumn and winter, compared with that of spring and summer. One explanation is that the longer aging process of PAHs in autumn and winter would result in volatilization from finer particles followed by condensation onto coarser particles. Another is there was mixing process of local emission with long-range transported aerosol in autumn and winter. The relative higher value of IcdP/(BghiP+IcdP) and lower value of BghiP/BeP in winter also give evidences to the mixing process. The level of PAHs concentration has been much elevated in recent years. This can be attributed to the fast growth of motor vehicle and energy consumption.     

Profile analysis of ambient and source emitted particle-bound polycyclic aromatic hydrocarbons from three sites in northern Greece

Polycyclic aromatic hydrocarbons (PAHs) adsorbed to ambient PM(10) were determined at three sites in Thessaloniki, northern Greece, during the period June 1997-July 1998. Ambient PAH profiles exhibited significant seasonal and spatial variations. Source PAH profiles were obtained for a number of urban, industrial and geological sources including cement, fertilizer and asphalt production, quarry operations, metal electroplating, metal welding and tempering, steel manufacture, lead and bronze smelters, metal scrap incineration, oil burning, non-catalyst equipped passenger cars, diesel fueled taxies and buses, paved road dust and soil dust. Principal component analysis (PCA) and diagnostic ratios were employed to compare ambient and source PAH profiles in an attempt to recognize compositional patterns. Similarities between the ambient PAH profiles and the profiles of certain sources, such as vehicular emissions, oil burning and metal industries, were identified.     

PAHs and nitrated PAHs in air of five European countries determined using SPMDs as passive samplers

The gas phase polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs in the atmosphere of five European countries (Austria, the Czech Republic, Poland, Slovakia and Sweden) were measured simultaneously during two 21-day passive sampling campaigns using semipermeable membrane devices (SPMDs). SPMD samplers, consisting of a pair of SPMDs covered by a metal umbrella, were deployed at 40 locations ranging from remote and rural to urban and industrial, at a similar time during each of the two sampling campaigns (autumn 1999, except in Poland, winter 1999, and summer 2000). The total amounts of PAHs and nitro-PAHs found in the SPMDs ranged between 5.0–1.2×10³ and 1.1×10⁻³–4.0 ng SPMD⁻¹ day⁻¹, respectively. The measured environmental sampling conditions were similar between sites and, thus, the variations in the SPMD data reflected the spatial differences in gas phase concentrations of nitro-PAHs and PAHs within and between countries. The gas phase concentrations of nitro-PAHs and PAHs found in East Europe (Slovakia, the Czech Republic and Poland 1999) were 10 times higher than those measured in Sweden, Austria and Poland in 2000. In each country, the levels of PAHs and nitro-PAHs differed by one–three orders of magnitudes amongst sampling sites. The highest within-country spatial differences were found in Poland where levels of PAHs and nitro-PAHs were about one and two orders of magnitudes, respectively, higher in winter 1999 than in summer 2000, probably due to increasing emissions of coal combustion for residential heating. Differences in PAH-patterns between sites were visualized by the multivariate projection method, principal component analysis (PCA). However, no specific source patterns were found, probably since imissions rather than emissions were measured, so the PAHs detected at many sites originated from multiple sources.     

Source apportionment and source/sink relationships of PAHs in the coastal atmosphere of Chicago and Lake Michigan

Multivariate statistical techniques were used to investigate source apportionment and source/sink relationships for polycyclic aromatic hydrocarbons (PAHs) in the urban and adjacent coastal atmosphere of Chicago/Lake Michigan in 1994–1995. The PAH signatures for the atmospheric particle phase, surface water particle phase and sediments indicate that atmospheric deposition is the major source of PAHs to the sediments and water column particulate phase of Lake Michigan. The PAH signature for the atmospheric gas phase and water dissolved phase indicate an intimate linkage between the lake and its overlying atmosphere. A modified factor analysis-multiple regression model was successfully applied to the source apportionment of atmospheric PAHs (gas+particle). Coal combustion accounted for 48±5% of the ΣPAH concentration in both the urban and adjacent coastal atmosphere, natural gas combustion accounted for 26±2%, coke ovens accounted for 14±3%, and vehicle emissions (gas+diesel) accounted for 9±4%. Each is an identified source category for the region. These results are consistent with the mix of fossil fuel combustion sources and ratios of indicator PAHs.     

Seasonal and long-term trends in atmospheric PAH concentrations: evidence and implications

Atmospheric monitoring data for selected polynuclear aromatic hydrocarbons (PAHs) were compiled from remote, rural and urban locations in the UK, Sweden, Finland and Arctic Canada. The objective was to examine the seasonal and temporal trends, to shed light on the factors which exert a dominant influence over ambient PAH levels. Urban centres in the UK have concentrations 1-2 orders of magnitude higher than in rural Europe and up to 3 orders of magnitude higher than Arctic Canada. Interpretation of the data suggests that proximity to primary sources 'drives' PAH air concentrations. Seasonality, with winter (W) > summer (S), was apparent for most compounds at most sites; high molecular weight compounds (e.g. benzo[a]pyrene) showed this most clearly and consistently. Some low molecular weight compounds (e.g. phenanthrene) sometimes displayed S>W seasonality at some rural locations. Strong W>S seasonality is linked to seasonally-dependent sources which are greater in winter. This implicates inefficient combustion processes, notably the diffusive domestic burning of wood and coal. However, sometimes seasonality can also be strongly influenced by broad changes in meteorology and air mass origin (e.g. in the Canadian Arctic). The datasets examined here suggest a downward trend for many PAHs at some sites, but this is not apparent for all sites and compounds. The inherent noise in ambient air monitoring data makes it difficult to derive unambiguous evidence of underlying declines, to confirm the effectiveness of international source reduction measures.     

Polycyclic aromatic hydrocarbons in the ambient air of Greek towns in relation to other atmospheric pollutants

Polycyclic aromatic hydrocarbons (PAHs) were determined in the ambient air of six towns in N. Greece. This paper presents the variability of the particle-bound PAHs concentrations and the particle PAH content during the cold and the warm months. Correlations of total PAHs with other atmospheric pollutants were largely different among towns indicating that the relative contribution of emission sources is different in each location. In the warm months PAHs were significantly correlated with vehicular pollutants thus suggesting traffic as the major PAH emmitting source. The same was also deduced from the comparison of the ambient PAH profiles to the profiles of particular sources. The contribution of residential heating was significant in most towns during winter. Principal component analysis of the data did not result in a clear distinction between towns thus suggesting that all are influenced by similar source types. Finally, the risk associated with the inhallation of carcinogenic PAHs in each town was estimated and compared to the risk from more urbanized/industrialized sites in N. Greece.     

Application of positive matrix factorization to identify potential sources of PAHs in soil of Dalian, China

Soil derived sources of polycyclic aromatic hydrocarbons (PAHs) in the region of Dalian, China were investigated using positive matrix factorization (PMF). Three factors were separated based on PMF for the statistical investigation of the datasets both in summer and winter. These factors were dominated by the pattern of single sources or groups of similar sources, showing seasonal and regional variations. The main sources of PAHs in Dalian soil in summer were the emissions from coal combustion average (46%), diesel engine (30%), and gasoline engine (24%). In winter, the main sources were the emissions from coal-fired boiler (72%), traffic average (20%), and gasoline engine (8%). These factors with strong seasonality indicated that coal combustion in winter and traffic exhaust in summer dominated the sources of PAHs in soil. These results suggested that PMF model was a proper approach to identify the sources of PAHs in soil.     

Polycyclic aromatic hydrocarbons in suspended particulate matter and sediments from the Pearl River Estuary and adjacent coastal areas, China

The spatial distribution, composition, and sources of polycyclic aromatic hydrocarbons (PAHs) in sediments and suspended particulate matter (SPM) from the Pearl River Estuary and adjacent coastal areas were examined. Total PAH concentrations varied from 189 to 637 ng/g in sediments and 422 to 1,850 ng/g in SPM. PAHs were dominated by 5,6-ring compounds in sediments and by 2,3-ring compounds in SPM samples. Assessment of PAH sources suggested that biomass and coal combustion is the major PAH source to the outer part of the estuary sediments and that petroleum combustion is the major PAH source to the inner part of estuary sediments. As for SPM samples, PAH isomer pair ratios indicated multiple (petroleum, petroleum combustion, and biomass and coal combustion) PAH sources, and significant temporal variations could exist for the sources of water column PAHs in the study area. The distribution of perylene in SPM samples indicated that the river was the dominant source of perylene in SPM and that perylene could be taken as an index to assess the contribution of river inflow to the total PAHs in SPM samples. The high concentration of perylene in the sediment was indicative of an in situ biogenic origin.     

Modelling the atmospheric fate and seasonality of polycyclic aromatic hydrocarbons in the UK

This paper presents the results from an exercise in atmospheric contaminant fate modelling, which had three main objectives: (1) to investigate the balance between estimated national atmospheric emissions of six selected PAHs and observed ambient measurements for the UK, as a means of testing the current emission estimates; (2) to investigate the potential influence of seasonally dependent environmental fate processes on the observed seasonality of air concentrations; and (3) after undertaking the first two objectives, to make inferences about the likely magnitude of seasonal differences in sources. When addressing objective 1 with annually averaged emissions data, it appeared that the UK PAH atmospheric emissions inventory was reasonably reliable for fluorene, fluoranthene, pyrene, benzo[a]pyrene and benzo[ghi]perylene--but not so for phenanthrene. However, more detailed analysis of the seasonality in environmental processes which may influence ambient levels, showed that the directions and/or magnitudes of the predicted seasonality did not coincide with field observations. This indicates either that our understanding of the environmental fate and behaviour of PAHs is still limited, and/or that there are uncertainties in the emissions inventories. It is suggested that better quantification of PAH sources is needed. For 3- and 4-ringed compounds, this should focus on those sources which increase with temperature, such as volatilisation from soil, water, vegetation and urban surfaces, and possible microbially-mediated formation mechanisms. The study also suggests that the contributions of inefficient, diffusive combustion processes (e.g. domestic coal/wood burning) may be underestimated as a source of the toxicologically significant higher molecular weight species in the winter. It is concluded that many signatory countries to the UNECE POPs protocol (which requires them to reduce national PAH emissions to 1990 levels) will experience difficulties in demonstrating compliance, because source inventories for 1990 and contemporary situations are clearly subject to major uncertainties.     

PAH deposition to snow surface

The urban snowpack effectively acts as a collection device for atmospheric-deposited PAHs. When these PAHs are flushed out in a short time interval along with springtime snowmelt, these cause shockloading to receiving waters. In order to assess the PAH deposition and accumulation in urban snowpacks, a deposition survey of PAH for the winter months of 1991-92 from the city of Sault Ste. Marie, Ontario, Canada was undertaken. The results of the survey are interpreted in view of prevailing meteorology and various emission sources in the study area. The relative PAH deposition levels (to BaP) are compared with relative source emission fingerprints to examine consistency in sampling and analysis. While analyzing the PAH samples using the ASTM (1987) method, the problem of concentration levels being below the detection level was encountered. The ASTM method for PAH analysis was modified to enhance the detection limit of the PAHs by concentrating the PAH extract to very low volumes, on the order of 200-300 microL.     

Characterization of atmospheric particulates, particle-bound transition metals and polycyclic aromatic hydrocarbons of urban air in the centre of Athens (Greece)

The concentrations of trace metals and polycyclic aromatic hydrocarbons (PAHs) adsorbed to total suspended particulate (TSP) and finer fractions of airborne particulate matter (PM) were determined from a site in the centre of Athens (Greece), which is characterized by heavy local traffic and is densely populated, during the winter and summer periods in 2003-2004. Also, we collected and analyzed samples of diesel and gasoline exhaust particles from local vehicles (buses, taxis and private cars) and from chimney exhaust of residential central heating appliances. A seasonal effect was observed for the size distribution of aerosol mass, with a shift to larger fine fractions in winter. The most commonly detected trace metals in the TSP and PM fractions were Fe, Pb, Zn, Cu, Cr, V, Ni and Cd and their concentrations were similar to levels observed in heavily polluted urban areas from local traffic and other anthropogenic emissions. Analysis of 16 PAHs bound to PM showed that they are mostly traffic related. In general, the fine particulate PAHs concentrations were higher than coarse particles. The most common PAHs in PM(10.2) and PM(2.1) were pyrene, phenanthrene, acenapthylene and fluoranthene, which are associated with diesel and gasoline exhaust particles. The results of this study underlined the importance of local emission sources, especially vehicular traffic, central heating and other local anthropogenic emissions. Compared with other big cities, Athens has much higher levels of airborne particles, especially of the finer fractions PM(10) and PM(2.5), correlated with traffic-related air pollution.     

Health and ecotoxicological risk assessment for human and aquatic organism exposure to polycyclic aromatic hydrocarbons in the Baiyangdian Lake

Seasonal and regional distributions of 17 polycyclic aromatic hydrocarbons (PAHs) in surface waters from four different main water functional regions of the Baiyangdian Lake were analyzed through GC/MS/MS during spring and summer season. The aim was to identify their possible pollution sources and evaluate their health risk for human and ecotoxicological risk for aquatic organisms. Results showed that the range of total PAH concentration is 35.38–88.06 ng/L (average 46.57 ng/L) in spring and 25.64–301.41 ng/L (average 76.23 ng/L) in summer. PAH contamination was observed slightly lower in the summer season from the pollution characteristics of water bodies in most areas of the Baiyangdian Lake, and the levels of PAH pollution in the water body of urban residential regions and rural residential regions were relatively higher than those in tourist regions and low human disturbance regions. Source analysis based on diagnostic ratios confirmed that combustion sources and petroleum sources were two main sources for PAHs entering into the waters of the Baiyangdian Lake. Human health risk assessment showed that PAHs in surface waters from the Baiyangdian Lake will not cause a potential non-carcinogenic risk to local residents and the carcinogenic risk could mostly be accepted, but the potential lifetime carcinogenic risk for infants in rural residential regions should be concerned about. Urban residential regions and rural residential regions were subject to higher cumulative non-carcinogenic and carcinogenic risk when compared to the other functional regions. Ecotoxicological risk assessment found a moderate risk to aquatic organisms presented by individual PAH and a low risk by total PAHs, and PAHs in the water body of urban residential regions and rural residential regions also have relatively higher harm effects to aquatic organisms compared with the other two functional regions. This study revealed the pollution characteristics of PAHs and their possible sources in waters of the Baiyangdian Lake, clarified its correlation to regional anthropogenic activities, and provided corresponding risk management strategies for human and aquatic organisms.

     

Obtaining polycyclic aromatic hydrocarbon concentration ratios and molecular markers for residential wood combustion: Temuco, a case study

It is known that residential wood combustion (RWC) is an important source of fine particle emissions. The purpose of this work was to characterize the chemical composition of the particulate matter present in the Temuco urban atmosphere during winter, specifically the polycyclic aromatic hydrocarbon (PAH) profile, because PAHs are considered to be among the key compounds in particulate matter toxicity. During the 2008 winter monitoring campaign, samples of particulate matter with aerodynamic diameters of < or = 10 (PM10) and < or = 2.5 (PM2.5) microm were taken on days with contamination episodes. Sixteen U.S. Environmental Protection Agency (EPA) PAH compounds were extracted with toluene and determined by gas chromatography-mass spectrometry (GC-MS). The results show that phenantrene was the predominant compound associated with particulate matter at a concentration range between 300 and 600 ng m(-3), 18 times higher than the second most abundant PAH compound. High-molecular-mass compounds such as dibenz[a,h]anthracene, benzo[g,h,i]perylene, and indeno[1,2,3,c,d]pyrene were also found, but they were minorities in the set. It was recognized from the PAH concentration ratios of the Temuco atmospheric aerosol that the main contamination source was in fact residential wood combustion; although not all the concentration ratios evaluated match the reported reference values, probably due to the kind of biomass used, the characteristics of Chilean heating appliances and climate.     

Daytime resolved analysis of polycyclic aromatic hydrocarbons in urban aerosol samples - impact of sources and meteorological conditions

Urban aerosol was collected in a summer and a winter campaign for 7 and 3 days, respectively. Low volume samples were taken with a time resolution of 160 min using a filter/sorption cartridge system extended by an ozone scrubber. Concentrations of mainly particle associated polycyclic aromatic hydrocarbons (PAH) and oxidised PAH (O-PAH) were determined by gas chromatography/high resolution mass spectrometry. The sampling site was located in the city centre of Augsburg, Germany, near major roads with high traffic volume. The daily concentrations and profiles were mainly governed by local emissions from traffic and domestic heating, as well as by the meteorological conditions. During the winter campaign, concentrations were more than 10 fold higher than during the summer campaign. Highest concentrations were found concurrent with low boundary layer heights and low wind speeds. Significant diurnal variation of the PAH profiles was observed. Enhanced influences of traffic related PAH on the PAH profiles were evident during daytime in summer, whereas emissions from hot water generation and domestic heating were obvious during the night time of both seasons. A general idea about the global meteorological situation was acquired using back trajectory calculations (NOAA ARL HYSPLIT4). Due to high local emissions in combination with low air exchange during the two sampling campaigns, effects of mesoscale transport were not clearly observable.     

Nitrogen isotopes: Tracers of origin and processes affecting PM10 in the atmosphere of Paris

Nitrogen in atmospheric particles in an urban environment is the result of complex primary and secondary processes, which renders identifying its origin somewhat complicated. Using the example of PM₁₀ in the atmosphere of Paris (France), it is shown that the use of stable nitrogen-isotope compositions (δ¹⁵N) alleviates this difficulty and provides clear information on the sources of primary and possibly of secondary nitrogen. Characterization of emissions of the different types of emitters in the city (road traffic, waste incinerators and heating sources) shows that these are clearly discriminated by specific isotope signatures. δ¹⁵N is particularly useful in showing that a substantial portion of the nitrogen is the result of secondary reactions, reactions that are different in summer and winter, as are the corresponding pollution sources. While it is unclear, among point sources, what the winter source of primary nitrogen is, road traffic appear to be the source of primary nitrogen in summer. Identification of the sources of the secondary nitrogen strongly depends on the nitrogen isotope fractionations (Δ¹⁵N) associated to atmospheric conversion of NO_x to nitrate, but hypothesises presented here hint at the possible corresponding pollution sources.     

Environmental Progress and Problems: A Chemical Industry Perspective

From 1995 to 2004, in Genoa, Italy, daily concentrations of twelve polycyclic aromatic hydrocarbons (PAHs) were measured in particulate phase (PM10), around a coke oven plant in operation from the 1950s and closed in 2002. The study permitted to identify the coke oven as the main PAH source in Genoa, causing constant exceeding of benzo(a)pyrene (BaP) air quality target (1.0 ng/m3) in the urban area till 1,900 meters distance downwind the plant. For this reason the plant was closed. Distance and daily hours downwind the coke plant were the main sources of variability of toxic BaP equivalent (BaPeq) concentrations and equations that best fitted these variables were experimentally obtained. During full plant activity, annual average BaPeq concentrations, measured in the three sampling sites aligned downwind to the summer prevalent winds, were: 85 ng/m3 at 40 m (site 2, industrial area), 13.2 ng/m3 at 300 m (site 3, residential area) and 5.6 ng/m3 at 575 m (site 4, residential area).

Soon after the coke oven's closure (February 2002) BaPeq concentrations (annual average) measured in residential area, decreased drastically: 0.2 ng/m3 at site 3, 0.4 ng/m3 at site 4. Comparing 1998 and 2003 data, BaPeq concentrations decreased 97.6% in site 3 and 92.8% in site 4.

Samples collected at site 3, during the longest downwind conditions, provided a reliable PAH profile of fugitive coke oven emissions. This profile was significantly different from the PAH profile, contemporary found at site 5, near the traffic flow.

This study demonstrates that risk assessment based only on distance of residences from a coke plant can be heavily inaccurate and confirmed that seasonal variability of BaPeq concentrations and high variability of fugitive emissions of PAHs during coke oven activities require at least one year of frequent and constant monitoring (10-15 samples each month).

Implications: Around a coking plant, polycyclic aromatic hydrocarbons (PAHs), concentrations depend mainly on downwind hours and distance. Equations that best fit these variables were experimentally calculated. Fugitive emissions of an old coke oven did not comply with the threshold BAP air concentration proposed by the World Health Organization (WHO), up to 1,900 m distance. The study identified the PAH profile of fugitive emissions of a coke oven, statistically different from the profile of traffic emissions. During its activity, in the Genoa residential area, 575 m away from the plant, 92.8% of found PAHs was due to coke oven emission only.