3.1. PM10 mass concentrations
Table 1 shows the mean atmospheric concentrations of PM10 as a whole and those of particulate compounds, namely n-alkanes, PAHs and polar substances, as well as those of gaseous PCBs and PAHs, observed at the five locations inside the factory. Figure 2 shows the PM10 mass concentration patterns. According to Table 1, mean PM10 concentration reached 46.7 µg m− 3 in PROD, 56 µg m− 3 in LABO, 42 µg m− 3 in OFFC, 59 µg m− 3 in CORR, and 95 µg m− 3 in RAWM. In RAWM, the PM10 rates ranged 73 ÷ 144 µg m− 3, exceeding 2–5 times those recorded elsewhere. The maximum observed at RAWM probably depended on limited air ventilation and on primary materials accumulated there, i.e. fillers, pigments, binders and solvents used in the manufacture of paints, and used as fine particles insoluble in the suspension medium (Can et al. 2015). Throughout the PM10 concentration rates, only 10 exceedances occurred of the limit value of 50 µg m− 3 set by Algerian legislation (PDRA-ED, 2006) and European normative (Directive 2008/50/EC).
Table 1
Mean suspended particle concentrations (PM10) and component loads at the study locations.
Site | PROD | LABO | OFFC | CORR | RAWM |
PM10 (µg m− 3) | 46.7 | 55.8 | 42.0 | 58.8 | 95.2 |
∑ PAHs (gaseous, ng m− 3) | 2 329 | 1 946 | 1 797 | 1 507 | 834 |
∑ PAHs (particulate, ng m− 3) | 34.7 | 16.3 | 7.0 | 15.4 | 12.8 |
∑ alkanes (particulate, ng m− 3) | 484 | 477 | 201 | 306 | 114 |
∑ polar cpds (particulate, ng m− 3) | 424 | 185 | 147 | 240 | 156 |
PCBs (gaseous, ng m− 3) | 0.6 | 42.4 | 10.9 | 3.2 | 1.1 |
3.2. Occurrence and composition of particle bound fraction (PBF)
3.2.1. n-Alkanes
Total n-alkanes (comprised of 21 homologues from tetradecane [C14] to tetratriacontane [C34]) associated with PM10 fraction ranged between 114 ng m− 3 (in the raw materials room) and 484 m− 3 (production area). Similar trends were observed at all sampling sites; C21 and C22 were the most abundant homologues during the whole period of investigation, while C14, C15 and C30-C34 were the poorest ones (Fig. 3). This pattern was indicative of anthropogenic emission prevailing vs. natural sources, as confirmed by the values (~ 1.2) of n-alkane Carbon Preference Index (CPI), calculated as the sum of the concentrations of odd carbon number alkanes divided by the sum of the even carbon number alkanes concentrations (Alves et al. 2014; Gheriani et al. 2022). The formulas we applied are:
CPI = ∑(C20-C32)/∑(C21-C33) (1)
3.2.2. Polycyclic Aromatic Hydrocarbons (PAHs)
The concentrations of twenty-six Polycyclic Aromatic Hydrocarbons (i.e., parent compounds and methyl-derivatives from phenanthrene to dibenzopyrenes) in the paint manufacturing plant are reported in Fig. 4.
Total PAHs associated with PM10 ranged from ~ 7.0 ng m− 3 to ~ 35 ng m− 3. An important spatial gradient was observed, with high concentrations in the production room and low in the office, which was situated in a relatively clean atmosphere. Besides, total PAHs reached 15.4 ng m− 3, 12.8 ng m− 3 and 16.3 ng m− 3, respectively, in the corridor, raw materials room and laboratory room. While the raw material room and corridor room were close to the production area, the PAH exposure inside the laboratory was low; on the other hand, the special profile of PAHs seemed to indicate that this location was affected by peculiar pollution sources; in particular, dibenzopyrenes (DBPs) touched their maximum in the laboratory, while they were almost absent in the office.. Indeed, the whole of paintings, methods and operations were tested there, which could characterize this microenvironment within the factory.
3.2.3. Highly-polar organic compounds (HPOCs)
Total contents of polar contaminants comprising five heterocyclic compounds, six phthalate esters and three nitrogen- and oxygen-containing compounds) ranged from 147 ng m− 3 in the office room up to 424 ng m− 3 inside the paint production zone, following a trend similar to n-alkanes. Among highly polar compounds, nicotine was predominant in all interiors, particularly in the production room and corridor; there, it accounted for 98% and 96%, respectively, of the total of polar substances (Fig. 5). This behavior was influenced by the huge tobacco smoking during work time (more in the production zone and in corridors than elsewhere), and also by the higher temperature indoors compared to outdoors; that occurred despite the concentrations determined in air could be somehow underestimated due to nicotine volatility (Eatough et al. 1989; Morawska and Zhang 2002).
The paint production zone was characterized also by high concentrations of phthalate esters PAEs, i.e. 10 ng m− 3 vs. ~1.0 ng m− 3 reached in the office. Among the six phthalates investigated, diethyl homologue (DEP) was all the-time the most important, though it is more volatile than dibutyl and diethylhexyl congeners. PAEs concentrations could be influenced, especially in the corridor, by additional emission sources like plastics, detergent bases and aerosol sprays used for cleaning (Tran and Kannan 2015). It is worth mentioning that PAEs are gaining concern as endocrine disruptors and toxic; besides, their combustion by-products display toxic properties (Gao and Wen 2016).
3.2.4. Polychlorobiphenyls (PCBs)
PCBs co-exist in the atmosphere as vapors and adsorbed on atmospheric particles (Gregoris et al. 2014). In this study, PCBs could be investigated only in the vapor phase, due to minimum concentrations ( < < 0.1 ng m− 3) reached by these compounds in airborne particulates. Indeed, in ambient air PCBs exhibit a marked preference of the gaseous phase except for the most chlorinated homologues (> Cl8), and only congeners from Cl3- to Cl6-CBs were detected in this study. Despite the method applied to collect and measure PCBs allowed drawing only semi-quantitative information, large differences among the five locations were put in the evidence.
The average concentration of gaseous PCBs was ca. 0.6 ng m− 3 in PROD, 42 ng m− 3 in LABO, 11 ng m− 3 in OFFC, 3.2 ng m− 3 in CORR and 11 ng m− 3 in RAWM. The maximum concentrations were observed in the laboratory, which was roughly 13 and 4 times more polluted than corridors and offices, respectively.
The results found in this study exceeded those reported in other Algerian cities such as in the suburban coastal zone of Bou Ismail (~ 0.03 ÷ 0.07 ng m− 3), Baraki (0.10 ÷ 0.15 ng m− 3, Moussaoui et al. 2012) and at the industrial cement plant in Sour el Ghozlane (~ 0.02 ng m− 3, Khedidji et al. 2017b). There were also much higher than in the European cities of Brescia (Colombo et al. 2013) and Madrid (Barbas et al. 2018), but were of the same order of magnitude of the heavily industrialized region of Kocaeli city in Turkey (4.2 ÷ 6.1 ng m− 3, Cetin et al. 2018).
3.2.5. Gaseous PAHs
Mean indoor concentrations of individual gaseous PAHs (GBF, expressed in ng m− 3 units) in the five interiors investigated are provided in Fig. 6.
The sum of non-alkylated and methyl substitute gaseous PAHs reached ca. 2,329 ng m− 3 in PROD, 1,946 ng m− 3 in LABO, 1,797 ng m− 3 in OFFC, 1507 ng m− 3 in CORR and 834 ng m− 3 in RAWM. Hence, gaseous PAHs were much more abundant than the particulate ones at all the locations of the factory premise.
Total PAHs at the PROD were significantly higher compared to the other sites, hence the paint manufacturing was suspected to be an important source of gaseous PAHs, because of the use of several solvents, thinners, varnishes and adhesives in this workshop. Low PAH concentrations were measured in the raw materials workshop, presumably due to the contents of materials used there, characterized by particulate rather than by vapours (see the section 3.1.). Another interesting finding was that PAHs concentrations measured in the office were higher than in the corridor, in accordance with odors perceived during the delivery of the samples, because the small office room suffered insufficient ventilation, unlike LABO and COR.
Nap, 1-Me Nap, 2-Me Nap and Me-2-Nap were the principal PAHs occurring among the 13 ones measured in the gas phase, and accounted for 42%, 15%, 8%, and 29% of the total, respectively. Naphthalene and their methylated derivatives are released by primary sources and react with OH radicals and NOx to produce secondary organic aerosols (SOA) (Chen et al. 2016). Further, several studies have simulated the gas-phase chemistry and particle-phase organic aerosol formation starting from naphthalene and alkyl naphthalene emission (Nishino et al. 2012; Lu et al. 2005 ; Kautzman et al. 2010).
3.3. PAHs distribution according to aromatic rings
Figure 7. Shows the PAHs percentage distribution according to aromatic ring number both in gaseous and particulate phases. The 6-ring congeners accounted for 65% of total PAHs in PROD, 61% in RAWM and 49% in COR and were the most abundant species of particulate phase, followed by 4-ring compounds, which accounted for 51% of the total in LABO and 48% in OFFC; on the other hand, the gaseous phase was dominated by the 2-ring PAHs, ranging from 93% in OFFC to 97% in LABO. Besides, in the gas phase 2-ring PAHs exceeded the 3-ring and 4-ring homologues by factors up to up to 31 and 44, respectively. Instead, when particulate PAH percentage profiles were compared, the 6-ring group was, on average, 6, 5 and 4 times more, respectively than the 3-ring group in PROD, RAWM and CORR; besides, the 4-rings PAHs were twice 3-rings PAHs. In conclusion, high molecular weight (HMW) PAHs (i.e., the 5- and 6-rings ones) were relatively rich in the particulate phase, whereas low molecular weight (LMW) PAHs (2-rings) were predominant in the gas phase, similarly to behavior of organic fuel burning (Tobiszewski and Namieśnik 2012). In particular, 4-rings PAHs have been related to coal combustion (Hu et al. 2019; Li et al. 2016). The important concentrations of 2-rings PAHs in the gas phase could depend on high temperature inside the premise, which promoted volatilization vs. adsorption on soot. In addition, the important occurrence of semi-volatile PAHs (4 rings PAHs) as particulate could depend on the total relative abundance in the air and phase partition (Pandey et al. 2011).
3.4. Diagnostic ratios (DRs) of gaseous and particulate PAHs
The emission percentage profile associated with PAHs sources such as industrial processes, petrol and diesel oil combustion, coal and wood burning (Mostert et al. 2010) depend on the mechanisms leading to PAHs release/formation. For instance, the low molecular weight PAHs are usually produced during low temperature processes; these PAHs are multi-alkylated and molecules contain less aromatic rings than pyrogenic PAHs (Zhang et al. 2008); besides, they can already occur in the fuels. On the other hand, high molecular weight PAHs are released by high temperature processes, such as fueled engine combustion. In order to determine the major sources of gaseous and particulate PAHs in five locations, we proceeded to calculate the concentration ratios of PAHs pairs (Khedidji et al. 2013, 2020; Balducci et al. 2014; Cecinato et al. 2014).
Among the diagnostic ratios (DRs) commonly examined for source identification, our concern was focused on the following ones: Phe/(Phe + Ant); Flu/(Flu + Pyr); BaA/(BaA + Chr) BeP/(BeP + BaP); IcdP/(IcdP + BghiP); and (alkylate PAHs/parent PAHs) (Table 2).
Table 2
Diagnostic ratios calculated for gas and particle phase air samples in this study
Ratios | Phases | PROD | LABO | OFFC | CORR | RAWM |
Ant/(Phe + Ant) | particle | 0.41 | 0.43 | 0.37 | 0.53 | 0.51 |
gas | 0.06 | 0.07 | 0.05 | 0.06 | 0.08 |
Flu/(Flu + Pyr) | particle | 0.32 | 0.33 | 0.37 | 0.33 | 0.35 |
gas | 0.62 | 0.64 | 0.65 | 0.58 | 0.62 |
alkylate PAHs/parent PAHs | Particle(Chr/Me-Chr) | 1.43 | 1.27 | 1.29 | 1.48 | 1.57 |
gas (Nap/Me-Nap) | 0.64 | 1.07 | 0.53 | 0.88 | 1.02 |
BeP/(BeP + BaP) | Particle | 0.60 | 0.55 | 0.54 | 0.42 | 0.58 |
gas | n.d. | n.d. | n.d. | n.d. | n.d. |
BaA/(BaA + Chr) | Particle | 0.15 | 0.22 | 0.21 | 0.30 | 0.21 |
gas | n.d. | n.d. | n.d. | n.d. | n.d. |
IcdP/(BghiP + IcdP) | particle | 0.37 | 0.40 | 0.38 | 0.51 | 0.35 |
gas | n.d. | n.d. | n.d. | n.d. | n.d. |
n.d. not detected |
According to DR rates, no significant differences were found between the five environments investigated inside the premise. The Ant/(Phe + Ant) ratio ranged from 0.05 to 0.08 for gas phase and from 0.37 to 0.53 for the particulate phase. Distinct values have been documented (rates < 0.1 or > 0.1, respectively) to distinguish petrochemical emission (e.g. lubricant oils and petrol-derived fuels) from solid fuel exhausts (coal) (Tobiszewski, et al. 2012).
Furthermore, the parent/alkylated PAHs ratio is considered as an index of petrogenic source contribution, because alkylated PAHs in petroleum products are more abundant than parent PAHs (Dobbins et al. 2006 ; Zakaria et al. 2002). The Nap/Me-Nap ratio was calculated for the gas phase, and Chr/Me-Chr ratio for particulate phase. Values of Nap/Me-Nap calculated at PROD, OFFC and CORR (0.5–0.9) and to a lesser extent those at the laboratory (1.1) and raw material workshop (1.0) put into evidence the contribution of petrogenic sources for gaseous PAHs, while Chr/Me-Chr ratio rates (1.0 to 1.6) confirmed that particulate PAHs originated overall from pyrogenic processes.
In the atmosphere BaP degrades faster than its isomer BeP (Khedidji et al. 2013; Rabhi et al. 2018) and both of them exist overall as particulates (Magnusson et al. 2016; Lui et al. 2015), so their concentration ratio is an index of particulate emission ageing. BeP/(BaP + BeP) ratio values are ~ 0.5 in fresh emissions (Ladji et al. 2014). This situation occurred all-the-time thorough the paint premise, where the ratio ranged 0.42–0.60.
According to the set of PAHs DRs proposed by Kavouras and his coworkers (Kavouras et al. 1998), the DRs analysis was conducted on the basis of Flu/(Flu + Pyr), BaA/(BaA + Chr), BeP/(BeP + BaP) and IcdP/(IcdP + BghiP) ratios, to compare the nonsmoking and tobacco smoking zones inside the factory. Particulate PAHs found in interiors appeared as originated mostly from tobacco smoking. In fact, Flu/(Flu + Pyr) ratio ranged 0.32 ÷ 0.37 and was similar to 0.34 determined in cigarette smoke (Table 2); similarly, BaA/(BaA + Chr) ratio t ranged 0.15 ÷ 0.30 (0.19 in cigarette smoke). BeP/(BeP + BaP) ranged 0.42 ÷ 0.60 and IcdP/(IcdP + BghiP) ranged 0.35 ÷ 0.51, i.e. values very close to 0.64 and 0.34, respectively, consistent with tobacco smoking. These results confirm the results relative to nicotine, which was very rich in the PM10 samples.
3.5. Principal component analysis (PCA) of particulate and gaseous PAHs
The principal component analysis (PCA) was performed in order to draw insights about the PAHs source nature in both phases, as well as to highlight links among compounds.
PCA was carried out using the statistical software (IBM, SPSS 25.0) and the Varimax rotated factor matrix method with Kaiser Normalization, based on the orthogonal rotation criterion maximizing the variance of the squared elements in the column of factors’ matrix. Variables having similar characteristics were grouped into specific factors, which indicated possible correlations between pollutants (Li et al. 2016).
The results of PCA (i.e., loading plot of 18 particulate PAHs, 13 gaseous PAHs and PCBs) are shown in Fig. 8. In the loading plot (Fig. 8a), Phe, Me-Phe, Pyr and Flu, Chr, Me-Chr, Me-Flu/Pyr, and BghiF lie at the bottom of the right; meanwhile, HMW-PAHs including the BaP, BbjkaF, Pery and IcdP are located mainly at the top of the left of the graph; hence, LMW- and HMW-PAHs were sequentially separated, confirming the influence of distinct emission sources. However, a handful of PAHs, like CPPyr, Ant and BghiP showed important differences in the scattering pattern. 2- and 3-ring PAHs (2Me-Na, Me-2-Nap, Acy, Phe, Ant and diMe-Phe/Ant) belonged to one only group (Fig. 8b).
Figure 8c shows the loadings plot of naphthalene, its methylated derivatives, total particulate PAHs and PCBs for each factor extracted by PCA. Naphthalene and methyl derivatives in this score plots are grouped with particulate PAHs, while PCBs are clearly separated. This seems to suggest that an important portion of the particulate PAHs may be secondary organic aerosol, which is formed by the oxidation of LMW-PAHs (Birgul and Tasdemir 2015). By contrast, PCBs originated from a distinct emission source.
The factor analysis results are presented in Table 3. Two factors were enough to explain most of the data variance. Factor 1 could explain up to 62.5% and 76.5% of the total variance for particulate) and gaseous PAHs (with strong loading of Phe, Me-Phe, Flu, Pyr, Me-Flu/Pyr, Chr, Me-Chr, BghiF and DBsumP, and 2Me-Nap, Acy, Fa, Phe, Me-Phe/Ant and DiMe-Phe/Ant, respectively). According to Li et al. (2013), Chr, Me-Chr, BkF and BbF are associated with petroleum combustion, whereas the Phe, Flu and Pyr are related to vehicular emission. On the other hand, Kulkarni and Venkataraman (2000) and Park et al. (2002) reported that Flu and Py are also originated from incineration sources, while, the 2Me-Nap, Acy and Fa (Table 4) are associated with pyrogenic sources with different combustion temperatures (Liu et al. 2015). Hence, PCA confirms what reported in previous Section 3.4 regarding the occurrence of pyrogenic emissions in LABO and RAWM.
Table 3
Factor loadings of particulates PAHs in the PCA analysis. Entries in bold indicate high factor loading
PAHs (Particle) | PC Component 1 | PC Component 2 |
Phe | 0.979 | 0.141 |
Ant | 0.685 | 0.545 |
MePhe | 0.973 | 0.033 |
Flu | 0.988 | 0.018 |
Pyr | 0.976 | 0.122 |
MeFluPyr | 0.833 | 0.381 |
BcPhe | 0.637 | 0.769 |
BaA | 0.416 | 0.901 |
Chr | 0.940 | 0.340 |
MeChr | 0.915 | 0.355 |
BghiF | 0.882 | 0.409 |
CPPyr | 0.407 | 0.571 |
BsumF | 0.056 | 0.978 |
Pery | -0.088 | 0.982 |
BeP | 0.626 | 0.775 |
BaP | -0.054 | 0.98 |
DBahA | -0.87 | 0.41 |
IcdP | -0.159 | 0.96 |
BghiP | 0.31 | 0.94 |
DBsumP | 0.81 | -0.103 |
Initial % of variance | 62.5 | 28.8 |
Cumulative % | 62.5 | 91.3 |
Sources | Petroleum, vehicular | biomass combustion |
Table 4
Factor loadings of gaseous PAHs in the PCA analysis. Entries in bold indicate high factor loading
PAHs (gas) | PC Component 1 | PC Component 2 |
Nap | -0.089 | 0.86 |
1-Me Nap | 0.44 | 0.87 |
2-Me Nap | 0.65 | 0.74 |
Me-2-Nap | 0.71 | 0.69 |
Acy | 0.87 | 0.42 |
Ace | 0.30 | 0.90 |
Fa | 0.96 | 0.106 |
Phe | 0.82 | 0.57 |
Ant | 0.66 | 0.72 |
Me-Phe/Ant | 0.99 | 0.096 |
DiMe-Phe/Ant | 0.77 | 0.62 |
Flu | 0.62 | 0.61 |
Pyr | 0.43 | 0.57 |
Initial % of variance | 76.5 | 12.6 |
Cumulative % | 76.5 | 89.2 |
Sources | pyrogenic | petroleum combustion |
Factor 2 explained 28.8% and 12.6% of the total variance for particulate and gaseous PAHs (with high loading of BaA, BsumF, Pery, BaP, IcdP, BghiP, and of Nap, 1Me-Nap, 2Me-Nap, Ace and Ant, respectively).
Previous studies suggested that HMW PAHs, such as BaP, BkF, IcdP and BghiP, are suitable tracers for high temperature processes such as burning of gasoline, diesel and biomass (Thang et al. 2019), while Nap, Ace, and Ant were associated with coal tar/coal combustion (Sofowote et al. 2008). Moreover, Kong et al. (2015) found that NaP was mainly derived from petroleum evaporation.
3.6. Partition of PAHs between particulate and gaseous phases
The concentrations of PAHs from phenanthrene to pyrene were determined both in gas and particle phase in interiors of the ENAP Company (Fig. 9). The sum of these concentrations (∑5 PAHs) in the gas phase ranged from 20 ng m− 3 in OFFC to 75 ng m− 3 in RAWM, with a mean of 47 ng m− 3, i.e. more than in particle phase, where they ranged 1.89 (RAWM) to 5.0 ng m− 3 (PROD) and reached a means of 2.85 ng m− 3.
As shown in Supplementary Information (Table S2), Phenanthrene (Phe) was found to be the most abundant in the gas phase, while methyl phenanthrene/anthracene isomers (Me-Phe/Ant) predominated in particulate phase. The important differences in the composition of gas and particle phase PAHs were consistent with the distinct source nature. Indeed, raw materials workshop was affected by the exhaust release from traffic, while the paint production area was quite rich in particulate PAHs and probably experienced the formation of secondary particulate matter under high temperature in the presence of oxidants (Ladji et al. 2009).
In comparison with other urban and industrial sites over the world (Table 5), PAHs concentrations observed in this study exceeded those measured at road traffic site in Umea, Sweden (Magnussan et al. 2016), at the ship traffic site in Venice, Italy (Gregoris et al. 2014), at the urban site in Zaragoza, Spain (Calln et al. 2008), and the background station in Gosan, Korea (Kim et al. 2012). On the other hand, PAH concentrations were lower than those measured during the Olympic Games in Beijing, China (Ma et al. 2011) and at the industrial site of Zonguldak, Turkey (Akyuz et al. 2010).
Table 5
Average gas and particulate PAHs (ng m− 3) measured in this study and in recent literature data.
Sampling sites | Lakhdaria, Algeria | Umea, Sweden | Venice, Italy | Venice, Italy | Beijing, China | Zonguldak, Turkey | Zaragoza, Spain | Gosan, Korea |
Feature | industry | road traffic | ship traffic | ship traffic | Olympic Games | industry | urban | background |
Period | 2014-15 | 2014 | 2012 | 2009 | 2008 | 2007-08 | 2003-04 | 2001-03 |
PHE | G | 39.1 | 1.2 | 0.86 | 1.6 | 43.1 | 106 | 2.2 | 0.55 |
P | 0.38 | 0.068 | 0.025 | 0.034 | 4.6 | 10.9 | 0.129 | 0.324 |
ANT | G | 2.44 | 0.11 | 0.023 | 0.034 | 7.3 | 26.2 | 0.45 | 0.031 |
P | 0.29 | 0.019 | 0.0025 | 0.003 | 0.5 | 4.6 | n.d. | 0.009 |
Me-PHE/ANT | G | 8.6 | 0.038 | n.e. | n.e. | n.e. | n.e. | 2.17 | n.e. |
P | 1.48 | 0.01 | n.e. | n.e. | n.e. | n.e. | 0.079 | n.e. |
FLU | G | 1.90 | 0.094 | 0.056 | 0.97 | 15.2 | 37.4 | 0.84 | 0.21 |
P | 0.31 | 0.13 | 0.044 | 0.68 | 12.3 | 31.8 | 0.23 | 0.53 |
PYR | G | 1.18 | 0.073 | 0.05 | 0.65 | 9.9 | 36.1 | 0.82 | 0.207 |
P | 0.62 | 0.13 | 0.051 | 0.46 | 10.5 | 24.9 | 0.31 | 0.36 |
Ref. | | a | b | b | c | d | e | f |
Symbols: G = gas phase; P = particulate phase; n.e. not examined; n.d. not detected |
References: a) Magnussan et al., 2016; b) Gregoris et al., 2014; c) Ma et al., 2011; d) Akyuz et al., 2010; e) Calln et al., 2008; f) Kim et al., 2012. |
3.7. Health risk assessment
The PM10-associated and gaseous toxicity were estimated by means of the equivalent carcinogenic potency of PAHs (BaPeq). BaPeq was calculated by multiplying the mass concentrations of each PAH compound times its corresponding toxic equivalency factor (TEFs); for this purpose, we applied the following formula (Kong et al. 2015):
BaPeq = 0.001*(Nap + Ace + Fa + Phe + Flu + Pyr) + 0.01*(Ant + Chr + BghiP) +
+ 0.1*(BaA + BbF + BkF + IcdP) + BaP + DBA (2)
Usually, toxicity of ambient PAHs is calculated looking to only particulate phase; despite that, though less carcinogenic most PAHs are emitted as vapors, and after release they partition between air and soot changing phase several times (Tasdemir and Esen 2007) depending on environmental contours.
The BaPeq rates calculated for the five sites are reported in Fig. 10. The maximum corresponded to PROD (19.7 ng m− 3) followed by RAWM (6.0 ng m− 3) for particulate PAHs, and to PROD and LABO (1.0 ng m− 3) for gaseous PAHs.
In the factory production area, the BaPeq daily values exceeded in both phases the maximum permissible risk level (i.e., 1 ng m− 3) set by the World Health Organization (WHO 2000). Moreover, particulate phase in the atmosphere of LABO, CORR and RAWM resulted more toxic (Fig. 10a) than elsewhere in Algeria (Yassaa et al. 2001; Ladji et al. 2009).
The health risk for humans can be estimated according to exposure through inhalation (Li et al. 2016). The incremental lifetime cancer risk (ILCR) is indexed through the lifetime average daily dose (LADD) of PAHs. The equations used to estimate LADD and ILCR are:
LADD = C x IR x ED x EF/(BW x ALT) (3)
ILCR = LADD x CSF (4)
Where C, instead of neat mass concentration of PAHs or PCBs (ng m− 3) in PM10 (Cetin et al. 2018; USEPA 2011), represents the sum of BaPeq of individual compounds (Jamhari et al. 2014); IR is the air inhalation rate (m3 day− 1, equal to 20 for adults); ED is lifetime exposure duration (52 years for adults); EF is the exposure frequency (260 days each year excluding weekends); BW is the body weight (70 kg for adults); ALT is the average lifetime for carcinogens (70 years × 365-day year− 1 = 25,550 days); CSF is the cancer slope factor. In this study, CSF value for BaP from inhalation is selected as 3.14 (mg kg− 1 day− 1) (Chen and Liao 2006).
The average body weight of Algerian by age-specific groups are based on the National Institute of Public Health Survey September 2010 (INSP 2010).
The calculated lifetime cancer risks for this study based on the mean BaPeq and PCBs loads are shown in Fig. 10b. The ILCR levels of particulate PAHs ranged from 3.6 * 10− 5 to 9.4 * 10− 4, and the maximum was recorded in the production area. ILCR for gaseous PAHs were fewer, i.e. from 2.1 * 10− 5 (at RAWM) to 4.7 * 10− 5 (at PROD). According to them, the daily inhalation dose of particulate PAHs and cancer risk to workers in the study sites exceeded the levels of 10− 6 to 10− 4 proposed as acceptable by USEPA (2005), while it did not occur for gaseous PAHs.
The mean exposure levels of PCBs ranged between 2.9 * 10− 5 at PROD to 2.0 * 10− 3 at LABO. The mean risk level exceeded 1*10− 3 in the laboratory and 1*10− 4 at the office and corridor, indicating a potential health risks associated to PCBs. Cancer associated with PCBs exposure is melanoma or fight liver, gall bladder, biliary tract, gastrointestinal tract, and brain (Cetin et al. 2018). The high exposure and inhalation risk levels calculated in the laboratory can be explained with the strength of PCBs sources there.