The Mass Distribution of Particle-Bound PAH Among Aerosol Fractions: A Case-Study of an Urban Area in Poland

Zabrze is one of the fourteen Silesian cities that form together the Silesian Agglomeration (Fig. 1-4). The Silesian Agglomeration lies in the center of the Silesia Province, occupies 1230 km2, its population is about 2.1 million (1691 inhabitants per one square kilometer). It is one of the most urbanized and industrialized regions of Central Europe. Such a dense concentration of people on such a heavily urbanized and industrialized area is unique in Europe. About 50% of the Silesia Province gross product and 7% of the gross domestic product come from the Silesian Agglomeration. Six European capital cities, Berlin, Prague, Wien, Bratislava, Budapest and Warsaw, lie within 600 km from Katowice, the capital city of the Agglomeration. The main transport routes linking Poland with Western Europe run through it in all directions. From the air protection point of view, the Silesian Agglomeration is one of the most interesting regions both in Poland and in Europe. Hard coal of better quality, mined in the western part of the Agglomeration since the 18th century, has been processed into coke and gas in five cities of the Agglomeration. Poorer quality coal, from the eastern part of the Agglomeration, is burnt in several great power stations, smaller power and heating plants, local heating plants and in domestic stoves. Almost all branches of industry, such as electrical, chemical, glass-making, textile, clothing, and ceramic industries, ferrous and nonferrous metallurgy, machine-building, hard coal mining and coking very actively have been deteriorating the natural environment for about 200 years. Nevertheless, three recent decades of economical changes forced in the Silesian Agglomeration the greatest in Poland drop of industrial air pollution (in Zabrze, yearly dust fall exceeded 2100 g m-2 in the 70s, oscillated between 700 and 800 g m-2 in the 80s, was less than 350 g m-2 after 1995). The concentration of the ambient particulate matter (PM) dropped significantly (Fig. 1). The greatest drop of the PM concentrations occurred between 1985 and 2000, when the total industrial emission of air pollutants drastically decreased in the effect of the transformation of the whole national industry and closing or restructuring of many great plants in the 80s. In 1990, the list of 80 Polish plants exerting the greatest impact on the

environment was announced. More than 20 of them were located in the Katowice Region whose the Silesian Agglomeration was a sub-region. The actions to lower the emission from these plants and limiting the output of heavy industry decreased the emission of dust and its gaseous precursors (Central Statistical Office of Poland [CSO], 1976[CSO], -2001 and halved the ambient concentrations of dust at measuring points (at the beginning of the 80s, in Dąbrowa Górnicza the PM concentration was almost 0.5 mg m -3 ). During the 90s, the PM concentrations continued to drop and since 2000 the yearly PM concentrations have remained constant at the approximate level between 65-110 µg m -3 depending on a measuring site. The industrial emission of PM and its precursors (SO 2 , NO x ) has also remained almost stable (Central Statistical Office of Poland [CSO], 2001[CSO], -2011.  1977(SSI, 1980 The concentrations of PM 10 1 , although slightly lower than in the 90s, are still high in the Silesian Agglomeration and have also been stabilized in each of the cities since 2000 (Fig. 2).  1993(SSI, 1980 The Provincial Inspector for Environmental Protection in Katowice [PIEP], 2002[PIEP], -2011 There are hundreds of organic compounds to be found in PM, among them more than one hundred polycyclic aromatic hydrocarbons (PAH). Since PAH tend to have low vapor pressures, they are usually adsorbed onto PM in the atmosphere. The vapor pressure of a PAH is inversely proportional to the number of rings it contains. As a result, the larger molecular weight PAH (≥ 4) are mostly adsorbed onto PM in atmospheric samples, while the lower molecular weight PAH can be found both free in the atmosphere and bound to particles. In some conditions, from 72% to even > 98% of four-, six-, and seven-ring ambient PAH are bound onto particles of PM 3 and PM 7 (Sheu et al., 1997). Seventeen PAH: acenaphtene (Acy), acenaphthylene (Ace), anthracene (An), benzo(a)anthracene (BaA), benzo(a)pyrene (BaP), benzo(e)pyrene (BeP), benzo(b)fluoranthene (BbF), benzo(j)fluoranthene (BjF), benzo(k)fluoranthene (BkF), benzo(g,h,i)perylene (BghiP), chrysene (Ch), dibenzo(a,h)anthracene (DBA), fluoranthene (Fl), fluorene (F), phenanthrene (Ph), pyrene (Py) and indeno(1,2,3-cd)pyrene (IP) are most often investigated. The most hazardous property of air pollutants is their carcinogenicity. Seven PAH: BaA, BaP, BbF, BkF, Ch, DBA and IP the USEPA classified as probable human carcinogens (http://www.epa.gov/). The most important natural sources of PAH are forest fires and eruptions of volcanoes. However, amounts of the natural ambient PAH are small compared to the amounts of the anthropogenic PAH. The majority of anthropogenic PAH come from incomplete combustion of fossil fuels or organic matter (Sienra et al., 2005;Zou et al., 2003). In urban air this www.intechopen.com includes PAH combustion in car engines and residential heating (Harrison et al., 1996;Manoli et al., 2004;Kristensson et al., 2004). Since 1977, in all cities of the Silesian Agglomeration, the State Sanitary Inspection (SSI, Department in Katowice) has measured ambient concentrations of PM-bound BaP continuously and 8 other PAH periodically (Fl, BaA, Ch, BbF, BkF, DBA, BghiP, IP; several years in each city). The total ambient concentration of these nine PAH drastically decreased in the period 1977-2005 (Fig. 3). The concentrations of PM-bound BaP dropped rapidly in all cities of the Agglomeration in 1980-1990. In each city the vast yearly concentrations of BaP from 1977BaP from -1981, reaching 500 ng m -3 in Ruda ląska, decreased several times during this decade. During the 90s, the concentrations of BaP dropped to less than 20 ng m -3 in each city of the Agglomeration. These concentrations have been still very high and hazardous to humans and the concentrations of PM 10 -bound BaP, measured since 2001, were high (Fig. 4), like the concentrations of PM-bound one. In general, the ambient particles with the aerodynamic diameter greater than 10 µm are not inhalable. Therefore, from the sanitary point of view, the concentrations of PM 10 should be the measure of the hazard from ambient particles. In all cities of the Agglomeration, the yearly average concentrations of PM 10 and PM 10 -bound BaP exceed their permissible levels (40 µg m -3 and 1 ng m -3 , respectively, Fig. 2). The limit of 40 µg m -3 on the yearly average concentration of PM 10 has been in effect in majority of the European countries for about 20 years (in Poland since 1998). Although the air quality has been improving for the latest thirty years, there is no city in the Silesian Agglomeration where this standard was not yearly exceeded in the period 1993-2010 (Fig. 2). Even the yearly average PM 2.5 concentrations, measured continuously since 2001 in Zabrze, exceed 25 µg m -3 , the standard for the PM 2.5 concentrations, every year Klejnowski et al., 2007aKlejnowski et al., , 2007bKlejnowski et al., , 2009PIEP, 2002PIEP, -2011. Although the spectacular reduction of the industrial emissions, especially of coarse dust, caused significant drop of the concentrations of PM and PM-bound BaP the PM 10 concentrations decreased only a little (Fig. 2). The poor air quality conditions in the cities of the Agglomeration are due to bad spatial arrangement of industrial and urban infrastructure. The industrial objects are interspersed with living quarters. The differences in the level of industrialization, urbanization and land use cause spatial non-homogeneity of the air pollution from industrial, municipal or vehicular sources even over small areas. The area of the Agglomeration is also affected by periodically occurring episodes of very high concentrations of air pollutants (especially of PM 10 in winter in city centers), which inflate the yearly PM concentrations. The inventory of the Silesian air pollution sources from 2006 contains 107 business entities emitting PM 10 and BaP within the Silesian Agglomeration (Air protection program [APP], 2010). In 2006, they emitted 4.9 Gg of PM 10 and 1.3 Mg of benzo(a)pyrene into the air. In average, this industrial emission was 44% and 28% of, respectively, the total PM 10 and BaP emissions in the Agglomeration. The municipal and household emission 2 , mainly from local heating plants and domestic stoves, have even greater share in the PM 10 and the BaP total 2 Heating plants and furnaces fed with solid fuel (mainly coal) are main sources of PM10 and BaP. They include small (local) heating plants and domestic stoves. In the Silesian Agglomeration, the estimated average of the household heat demands covered by solid fuel combustion in domestic stoves is still greater than 34%. The emissions of PM10 and PM10-bound BaP from the solid fuel furnaces are more than 94% of their totals in the surface emission. It is due to bad technical condition and age of the heating plants and stoves and also to the poor quality of the combusted coal.
concentrations. In 2006, it was 5.3 Gg and 3.2 Mg, what made 47% and 71% of the total PM 10 and BaP emissions. This contribution is even greater in a heating season-in winter.  1992(SSI, 1993 The elevated autumn and winter PAH concentrations in the Agglomeration my be linked with the emission from municipal sources. The seasonal dependence of the PM-bound PAH concentrations was observed in three Silesian cities: Katowice, Sosnowiec and Zawiercie in 2008. The seasonal PAH concentrations were 5.1-18.6 ng m -3 in spring, 5.4-7.6 ng m -3 in summer, 6.8-24.0 ng m -3 in autumn and 26.2-61.3 ng m -3 in winter (Zaciera et al., 2010). Although the reduction of the industrial emission improved the air quality in the Silesian Agglomeration the hazard from PM 10 (especially from the smallest particles) might grew owing to growth of vehicular emission. For the last two decades, the Poles have imported more than 920000 second-hand cars yearly. Majority of the cars were older than 10 years, they did not meet the emission standards and had high fuel-consumption. In Gliwice, from April to June 2003, in a trafficked street canyon (1400 vehicles per hour), the average PM 10 concentration was 94.0 µg m -3 and was higher by 40.0 µg m -3 than the one measured 100 m apart. The average concentration of total PAH, equal to 191.56 ng m -3 , was 1.5 times greater than the background concentration (Grynkiewicz-Bylina et al., 2005). In Zabrze, in summer 2005, the average concentration of the total PM 10 -and the total PM 2.5bound PAH at crossroads were 65.6 ng m -3 and 44.4 ng m -3 , and were 1.9 and 3.4 times greater than the background concentrations, respectively (Ćwiklak et al., 2009). In Bytom, on www.intechopen.com the turn of February and March 2007, the average concentrations of the total vehicular PM 2.5 -and the total vehicular PM 10 -bound PAH were between 56.2 and 73.4 ng m -3 and 75.1 and 91.0 ng m -3 , respectively. The significant in this city influence of the industrial emission and the emission from low sources was excluded by proper location of the measuring points (Kozielska et al., 2009).  (SSI, 1982(SSI, -2006PIEP, 2005PIEP, -2011 The hazard from the air pollution in the neighborhood of trafficked roads is also elevated by the elevated toxicity of traffic PM 10 containing allergens and carcinogens, also PAH (Kinney et al., 2000;Pakkanen et al., 2003;Vogt et al., 2003). Now, in the Silesian Agglomeration, when the number of industrial and of the vast fugitive emission sources of PM (mine heaps, dumps) decreased, main PM and PAH sources are domestic furnaces, heat and power plants and road traffic. In the Agglomeration, the industrial and the municipal sources contribute to the air pollution much more than such sources in the Western Europe countries (EMEP, 2009), and the role of vehicular emission grows. As a result, the proportion of fine particles in PM increases. Ambient fine particles have relatively great surface to adsorb PAH (Ravindra et al., 2001;Sheu et al., 1997), so the fine dust is richer in PAH than the coarse one. Therefore, investigation of the particle size distribution of PM and the PAH content of PM fractions is crucial to abate the adverse effects of PM.
The work presents the method and the results of the investigations of the mass distribution of some PM-bound PAH among the PM fractions in the Silesian Agglomeration. The investigated PAH, three-ring: Acy, Ace, F, Ph, An, four-ring: FI, Py, BaA, Ch, five-ring: BbF, BkF, BaP, DBA and six-ring: BghiP, and IP, are on the USEPA CWA list of the priority pollutants.

Methods
The site in Zabrze, selected for the experiment, is representative of the air pollution conditions typical in the Silesian Agglomeration -by the Directive 2008/50/EC definition, it is an urban background measuring point (Directive, 2008). The effects of the industrial and the municipal emissions on living quarters of the Agglomeration are represented and may be observed here very well. Ambient dust was sampled with the use of a thirteen stage DEKATI low pressure impactor (DLPI), which collects thirteen PM fractions onto thirteen separate substrate filters ( Table 1). The principle of DLPI operating may be found in (Klejnowski et al., 2010). There were two periods of sampling: from 7 May to 2 August (summer) and from 26 October to 27 December (winter) 2007. One sample-taking lasted about one week. Seven such sample-takings were done in winter and nine in summer, the measurements covered the sampling periods in 98 and 92%, respectively, and whole summer (2nd and 3rd quarter of 2007) and winter (1st and 4th quarter of 2007) in 27% and 45%. The mass of the dust collected on aluminum substrates was determined by weighing the substrates before and after exposure on a Mettler Toledo micro-balance. Before weighing, the substrates were kept in the weighing room for 48 hours (temperature 20±2 0 C, relative air humidity 48±5%). The concentrations of the fractions of PM were computed from the volume of air passed through the impactor and the masses of the dust collected on its stages. All the samples (substrates), till analyzing, were kept in a refrigerator in tight and lightproof containers. The winter and summer samples were developed separately. For each of the thirteen PM fractions, all its samples (7 in winter and 9 in summer samples per fraction) were extracted together in an ultrasonic bath in dichloromethane (CH 2 Cl 2 ). The extract was percolated, washed and dried by evaporating in the helium atmosphere. The dry residue was diluted in propane-2 (CH 3 CH(OH)CH 3 ) and distilled water was added to receive the proportion 15/85 (v/v) of propanol-2 to water. For selective purification, the resulting samples were solidified (SPE) by extracting in columns filled with octadecylsilane (C 18 , Supelco). PAH were eluted with the use of dichloromethane (CH 2 Cl 2 ). The extract of a PAH fraction was condensed in the helium atmosphere to the volume of 0.5 cm 3 . The samples were analysed on a Perkin Elmer Clarus 500 gas chromatograph with a Flame Ionization Detector (FID). An  Restek capillary 30 m x 0.32 mm x 0.25 μm column was used to separate the sample components. The flow of the carrier gas, helium, was 1.5 cm 3 min -1 . Calibration curves for 15 PAH standards were used in quantitative determinations. The linear correlation of the surfaces of the peaks with the PAH concentrations was checked in the concentration range 1 -4 ng μl -1 . The correlation coefficient ranged from 0.90 to 0.97. The time of the whole analysis was 40 min. FID was provided with hydrogen (45 cm 3 min -1 ) and air (450 cm 3 min -1 ). The recoveries of PAH were determined using a standard containing the 15 PAH. They ranged from 85% to 93%.

Concentrations of PM-and PM-bound PAH. Origin of PAH in Zabrze
The winter PM 10 concentrations exceeded 46 µg m -3 , the summer ones reached almost 19 µg m -3 (Table 1). Such a difference is due to very high emission of PM from combustion of fossil fuels in winter, specific of the Silesian Agglomeration (Rogula-Kozłowska et al., 2008;Pastuszka et al., 2010). The average concentrations of PM 10 and PM in the experimental period (33.5 µg m -3 and 32.5 µg m -3 ) were lower than the yearly concentrations of PM 10 in 2007 and PM in 2005 ( Fig. 1 and 2). The explanation may by that the former were sampled with DLPI at about 5 m above the ground level during about 16 weeks, missing a part of winter when in Zabrze the highest PM concentrations occur (Klejnowski et al., 2007a(Klejnowski et al., , 2009, the latter were measured by SSI at the height 2.5 m during the whole year.  In winter, the PM concentrations and the concentrations of majority the PM fractions were two or three times higher than in summer. For PM 0.03-0.06 it was 4.5, for PM 0.17-0.26 more than 5 and for PM 0.26-0.40 almost 4 times ( Table 1). The PM 2.5-10 concentrations in summer were close to or higher than the PM 2.5-10 winter concentrations. The masses of PM 2.5 and PM 1 were 89 and 72% in winter and 68 and 51% in summer of the mass of PM 10 , respectively (Fig. 5). The concentrations of ΣPAH behaved similarly. In winter, the concentrations of PM 2.5 and PM 1 -bound ΣPAH were 99 and 82% of the PM 10bound ΣPAH concentrations; in summer it was 77 and 69%, respectively. Despite the disparities between the concentrations of PM 1-, PM 1-2.5 and PM 2.5-10 -bound ΣPAH in both seasons (Fig. 5), the mass contributions of ΣPAH to PM 1 , PM 1-2.5 , and PM 2.5-10 was 0.02-0.04% in summer and 0.38, 0.34 and 0.04% in winter, respectively. In each season, PM 1 and PM 1-2.5 had almost equal PAH contents. It means that in each season, PM 1 and PM 1-2.5 as well as PM 1 -and PM 1-2.5 -bound PAH came from the same sources. The differences between the summer and the winter concentrations of the fraction-bound ΣPAH are greater than the differences between the concentrations of the PM fractions. The concentrations of ΣPAH bound onto PM 0.17-0.26 , PM 0.26-0.40 , PM 0.40-0.65 , PM 0.65-1.0 , PM 1.0-1.6 are greater from 21 to 251 times in winter than in summer. Noticeably, these fractions are usually formed by primary particles originating from combustion (Chow, 1995;Zhao et al., 2008;Wingfors et al., 2011). For each of PM 0.06-0.108 , PM 0.108-0.17 , PM 0.17-0.26 , PM 0.26-0.40 , PM 0.40-0.65 and PM 1.6-2.5 , among the fifteen PAH bound onto each of these fractions, Ph, one of the markers of emission from car engines (Harrison et al., 1996), had the highest summer concentrations. The summer concentrations of F, Py, An and Ch bound onto these fractions were also high. These PAH are also attributed to combustion of gasoline and oil in car engines Miguel et al., 1998). In winter, Py, BaA, Ch, BbF and BkF had the greatest concentrations among the 15 PAH in each of these fractions. They belong to CPAH (Prahl & Carpenter, 1983), the nine so called combustion PAH (Fl, Py, BaA, BbF, BkF, BaP, BeP, IP and BghiP; Rogge et al., 1993aRogge et al., , 1993bKavouras et al., 1999;Bi et al., 2002;Manoli et al., 2002Manoli et al., , 2004Sienra et al., 2005). In winter, about 80% of the mass of these PAH was in PM 1 . In summer, almost 100% of DBA and BghiP and about 80% of IP were in PM 1 . Each of the remaining PAH was contained in particles greather than 1 μm at least in several dozen percent (Fig. 6). In summer, the concentration of PM 1 -bound BaP was a little more than 20% of the concentration of PM 10 -bound BaP. The concentrations of BaP were greatest among the concentrations of PM 1-2.5 -and PM 4.4-6.8 -bound PAH. The winter and the summer profiles of PM-bound PAH differ. In winter, five-and four-ring PAH were 87% of PM-bound ΣPAH. In summer, five-and four-ring PAH were only 58.5% of PM-bound ΣPAH. Three-ring PAH were 39.1% of PM-bound ΣPAH in summer, six-ring PAH were 6.6% and 2.4% of PM-bound ΣPAH in winter and summer, respectively (Table 1). In winter, PM 0.26-0.40 , PM 0.40-0.65 , PM 0.65-1.0 , PM 1.0-1.6 were richest in PAH (Fig. 7). PM 0.26-1.6 contained more than 88% of each: ΣPAH, six-, five-and four-ring PAH; for three-ring PAH it was over 67%. In summer, the PM fractions of PAH between the fractions was uniform except for six-ring PAH, whose contribution to PM 0.03-0.06 was over 73%. to approximately 0.1 μm, the accumulation mode -the mass distribution of the particles with diameters in the interval 0.1-2 μm, and the coarse mode is for the particles with diameters greater than 2 μm (Willeke & Whitby 1975;Sverdrup & Whitby, 1977;Hinds, 1998). In practice, the particles in the nucleation mode weigh very little and the mass distribution density may have only two maxima, representing the accumulation and the coarse modes. In Zabrze, in summer 2007, the PM mass distribution with respect to the particle aerodynamic diameter was bimodal. The probability density function had two maxima, one in the interval of particle diameters 0.4-0.65 µm (accumulation mode), and the second between 6.8 and 10 μm (coarse mode, Fig. 8). In winter, the mass distribution was unimodal, the density function had its only maximum between 0.26-0.4 µm. In winter, the PAH and ΣPAH mass distributions with respect to particle aerodynamic diameter of the particles they were adsorbed onto, except for the three-ring PAH, were bi-or trimodal, with one mode, like for PM, between 0.26 and 0.4 μm ( Fig. 9 and 10). The second maximum occurred usually between 0.65 and 1.0 μm (except for BbF, BkF, BaP) and the third one between 4.4 and 6.8 μm or 6.8 and 10 μm (except for BaA, IP, DBA and BghiP). Three-ring PAH, in winter and in summer, were not detectable in some PM fractions (Table  1) because the lighter than Ph ambient species occur in the gaseous form (Guo et al., 2003;Fang et al., 2006;Akyüz & Çabuk, 2008). In summer, ΣPAH and, in general, four-, five-, and six-ring PAH (Fl, Py, Ch, BbF, BkF, BaP) had tri-or bimodal distributions. The distributions of IP and BghiP were bimodal, and of DBA-unimodal. Like in winter, in summer too, majority of the probability functions of PAH and the function of ΣPAH had one maximum between 1.0 and 1.6 μm or 1.6 and 2.5 μm and the second between 4.4 and 6.8 μm or 6.8 and 10 μm (coarse particles). The PAH diagnostic ratio (DR) is a proportion of ambient PAH concentrations. DR, in some way characterizes the origin of the involved PAH. In the present work, DR are used to determine the effect of the combustion sources in Zabrze on the concentrations of PAH bound to some PM fractions (PM 1 , PM 2.5 , PM 10 and fractions where the majority of the probability functions of size distributions of PAH or ΣPAH concentrations assume their maximum). Some DR were taken from literature ( Coal combustion > 0.5 [3,4] 0.57 [10] 0.46 [10] 0.50 b) [11] 0.17 -0.36 [12] 3.5 -3.9 [14] 0.76 [15] Wood combustion 1.0 [1] > 0.5 [3,4] 0.51 [9,10] 0.40 ± 0.09 [6] 0.8 -1.1 [14] Natural gas combustion 0.49 [9,10] Other sources 2.5 -2.9 c) [14] > 0.7 d) [16] a) Vehicular emissions -converter equipped automobiles; b) Coal combustion for domestic heating; c) Smelters; d) Associated with lubricant oil and fossil fuels; e) Non-catalyst automobiles; f) Catalystequipped automobiles; g) General dominance of combustion sources [1] : (Li & Kamens, 1993); [2] : (Kavouras et al., 1999); [3] : (Zencak et al., 2007); [4] : (Yunker et al., 2002); [5] : (Rogge et al., 1993a(Rogge et al., , 1993b; [6] : (Sicre et al., 1987); [7] : (Ravindra et al., 2006); [8] : (Ravindra et al. 2008); [9] : (Galarneau, 2008); [10] : (Tang et al., 2005); [11] : (Gschwend & Hites, 1981); [12] : (Dickhut et al., 2000); [13] : (Masclet et al., 1987); [14] : (Khalili et al., 1995)  The effect of stationary combustion sources on the ambient PAH concentrations is characterized by the proportion ΣCPAH/ΣPAH of the PM-bound ΣCPAH and ΣPAH concentrations (Rogge et al., 1993a(Rogge et al., , 1993bKavouras et al., 1999;Manoli et al., 2004;Sienra et al., 2005). In Zabrze, ΣCPAH/ΣPAH indicate that in winter PM 0.26-0.4 -, PM 0.65-1.0 -and PM 1.6-2.5 -bound PAH came from stationary combustion sources (Table 2 and 3). In winter, these fractions contained half of the mass of the PM-bound PAH and, not surprisingly, the winter PM 1 -, PM 2.5 -and PM 10 -bound PAH should in general come from stationary combustion.
In summer, PM 1 -and PM 2.5 -bound PAH might also have come from vehicular sources (ΣCPAH/ΣPAH was lower than in winter) but the summer concentrations of PM 1.6-2.5 -, PM 6.8-10 -and PM 10 -bound PAH were affected by stationary combustion sources as well. However, in summer, the degradation processes (oxidation, photochemical reactions) and in winter the variability of the parameters of combustion processes and the variety of used fuels limit the reliability of DR making the source apportionment uncertain (Kavouras et al., 1999;Hong et al., 2007) (Rogge et al., 1993a(Rogge et al., , 1993b.

Comparison of the concentrations of PM-and PM-bound PAH in Zabrze and selected sites in the world
The ambient concentrations of PAH bound to various PM fractions, especially to PM 2.5 and PM 10 , are investigated at many sites in the world (Kavouras et al., 1999;Odabasi et al., 1999;Panther et al., 1999;Takeshi & Takashi, 2004;Mantis et al., 2005). Most often, the investigations cover short periods, results of long-term experiments are not abundant. The direct comparison of the concentrations of PM-bound PAH from various urban areas should be done cautiously. The data may be affected by the method of sampling and the technique of determination of PAH in the dust samples (Takeshi & Takashi, 2004). The local conditions, meteorological (air temperature and relative air humidity, direction and velocity of wind, precipitation) and other, neighborhood of the sampling point, a season of a year are also important Evagelopoulos et.al., 2010). The ranges of the concentrations of BaP and ΣPAH are wide because of the causes mentioned above and different numbers of PAH in ΣPAH. In general, the lowest concentrations (lower than 0.1 ng m -3 for BaP and than 2 ng m -3 for ΣPAH) occurred in clean areas (not affected by vehicular or industrial sources), such as Virolahti (regional background station) in Finland (Makkonen et al., 2010) and Chréa National Park (great forest area) in Algeria (Ladji et al., 2009). In most places the BaP concentration did not exceed 1 ng m -  (Ćwiklak et al., 2009). Majority of ambient PAH, especially in urbanized areas, are anthropogenic (Kulkarni & Venkataraman, 2000;Hien et al., 2007;Wang X.H. et al., 2007), and come mainly from combustion of fossil fuels, wastes or biomass and also from industry and road traffic. Most of the greatest values of BaP concentrations shown in Table 4, reaching 50 ng m -3 , come from sites located in industrialized and densely populated areas in Asiatic countries, such as Fushun (residential-commercial site, Kong et al., 2010), Beijing (campus site, Wang H. et al., 2009), Guiyu (electronic waste recycling site, Deng et al., 2006) in the People's Republic of China or Chennai in the Republic of India (Mohanraj et al., 2011). The concentrations of ΣPAH in these regions were also high, some times, like in Funshun, China, where the ΣPAH concentration reached 1.9 μg m -3 , many times higher than elsewhere in the world. In Europe, the highest BaP and ΣPAH concentrations were at traffic station in Sweden and at traffic and urban sites in Zabrze (Table 4). BaP and ΣPAH tend to accumulate in the finest particles of PM (Table 4). Like in Zabrze, this tendency may be observed in the road tunnel in Lisbon, Portugal (Oliveira et al., 2011) and at the urban background and traffic stations in Los Angeles, USA (Phuleria et al., 2007).

Concentration (ng·m -3 ) BaP a) ∑PAH b)
Zabrze ( (Kong et al., 2010);19) : (Mohanraj et al., 2011);20) : (Hien et al., 2007); 21) : (Ladji et al., 2009);22) : (Ding et al., 2009);23) : (Krudysz et al., 2009);24) : (Phuleria et al., 2007) (Odabasi et al., 1999;Hong et al., 2007). Therefore, lower in summer than in winter concentrations of PM-bound PAH may also be due to releasing of PAH from PM particles. To prove it in Zabrze, the gas phase of ambient PAH would have to be investigated. In summer, more favorable conditions for dispersion and dilution of air pollutants (Mantis et al., 2005) and washing out of particles (with adsorbed PAH) by precipitation occur. The concentrations of BaP and ΣPAH in Zabrze in summer 2007 were lower than in 2005 (Table 4). It may be due to the differences in the sampling periods ( Nevertheless, the concentrations at two measuring points in Zabrze in summer 2005, several times lower than in winter 2007, suggest that the municipal emission in Silesian Agglomeration may be much greater problem than the traffic emission. Instead, in other European cities, the greatest problem is the traffic emission. The ΣPAH concentrations in Zabrze in 2007 were higher than in other European cities except for the traffic sites (road tunnels) in Marseille (France) and Lisbon (Portugal).

Health hazard from PAH in Zabrze
Ambient PAH endanger human health by their mutageneity and carcinogenicity. Their strong adverse biological effect is documented by numerous works (Grimmer et al., 1986;White, 2002;Yan et al., 2004). The risk from the exposure to particular PAH is expressed in terms of the most cancerogenous PAH, BaP, as the toxicity equivalence factor (TEF). The carcinogenicity of a combination of PAH, the BaP equivalence (BEQ), is computed as the linear combination of the concentrations of PAH entering the PAH combination and their TEF (Nisbet & LaGoy, 1992). BEQ for the 15 PAH discussed in this paper is:  Hong et al., 2007). In Zabrze, in summer, the values of ΣPAH carc /ΣPAH were between 0.17 and 0.74 (Table 5). They are dispersed owing to differentiation of the PAH profiles (Table 1). The winter ΣPAH carc /ΣPAH are close to or higher than 0.5. In general, in Zabrze, the values of ΣPAH carc /ΣPAH were high, much higher than ones determined for other urban areas (Bourotte et al., 2005;Sienra et al., 2005). They are comparable with the values received by Chen et al. (2004) for dust emitted from coal combustion.

Conclusion
In Zabrze, the winter PM-bound BaP concentrations are 19 times greater than the limit for the yearly average BaP concentrations (1 ng m -3 ). Both PM-bound BaP and Σ15PAH concentrations are much greater than the concentrations in other European cities. Despite the general improvement of the air quality in the Silesian Agglomeration during the last thirty years (decrease of the concentrations of ambient coarse particles and PAH related with this fraction), the concentrations of PM-bound BaP and Σ15PAH are high. On the local scale, in winter, the most important sources of fine particles and particle-bound PAH are municipal sources (hard coal, wood and garbage combustion), and/or electric power and heat production from coal; in summer it is vehicular emission. At the urban background measuring point in Zabrze, the vast differences in the seasonal ambient concentrations of PAH and in PAH profiles refute the supposition on industry affecting mostly the air quality in the Silesian Agglomeration. However, DR applied in determination of probable PAH sources are not reliable and their application may give contradictive results (Simcik et al., 1999;Sienra et al., 2005;Evangelopoulos et al., 2010;Dvorská et al., 2011). The exact apportionment of PAH to sources needs measuring of the diurnal PM-bound PAH concentrations and some statistical reasoning must be done (e.g. multivariate factor analysis to apportion combinations of PAH to sources). The data base containing the intervals of DR determined for the specific conditions in the Silesian Agglomeration in vicinities of real PAH sources would appear very helpful. Also, the measurements of ambient gaseous PAH concentrations are necessary. The high ambient PAH concentrations and the high five-and six-ring PAH content of total PAH are hazardous to the Zabrze population, especially in winter. The concentrations of the carcinogenic PAH was never lower than 50% of the ΣPAH concentration in winter, and BEQ for PM 1 , PM 2.5 and PM 10 were 35.93 ng m -3 , 41.72 ng m -3 and 41.91 ng m -3 , respectively. In winter, all the four-, five-and six-ring PAH and ΣPAH had two-or trimodal distributions with one maximum between 0.26 and 0.4 μm, the second usually between 0.65 and 1.0 μm and the third between 4.4 and 10 μm. The greatest BEQ and ΣPAH carc /ΣPAH found for PM 0.17-1.6 suggest elevated toxicity of very fine particles, which are the core mass of PM, in Zabrze in winter. In summer, the distribution of ΣPAH and particular PAH with respect to the aerodynamic diameter of particles they are bound to, the values of BEQ and ΣPAH carc /ΣPAH were similar to those from other sites in the world Akyüz & Çabuk, 2008). The contribution of PM 1 -and PM 2.5 -bound ΣPAH to ΣPAH was in Zabrze, like elsewhere (Chrysikou et al., 2009;Kong et al., 2010;Makkonen et al., 2010;Oliveira et al., 2011), very high (99 and 82% in winter and 77 in 69% summer, respectively).

Acknowledgment
The work was partially supported by grant No. N N523 421037 from the Polish Ministry of Science and Higher Education.

References
Air protection program for areas of Silesia, which were found oversize levels of substances in the air. Ten years after coming into force of the Stockholm Convention on Persistent Organic Pollutants (POPs), a wide range of organic chemicals (industrial formulations, plant protection products, pharmaceuticals and personal care products, etc.) still poses the highest priority environmental hazard. The broadening of knowledge of organic pollutants (OPs) environmental fate and effects, as well as the decontamination techniques, is accompanied by an increase in significance of certain pollution sources (e.g. sewage sludge and dredged sediments application, textile industry), associated with a potential generation of new dangers for humans and natural ecosystems. The present book addresses these aspects, especially in the light of Organic Pollutants risk assessment as well as the practical application of novel analytical methods and techniques for removing OPs from the environment. Providing analytical and environmental update, this contribution can be particularly valuable for engineers and environmental scientists.