Particle-bound PAHs quantification using a 3-stages cascade impactor in French indoor environments

Environmental Pollution 195 (2014) 64e72

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Particle-bound PAHs quantification using a 3-stages cascade impactor in French indoor environments
line Liaud a, Thierry Dintzer a, Vale
rie Tschamber b, Gwe
nae €lle Trouve b, Ce
phane Le Calve
a, c, * Ste Institut de Chimie pour les Proc
ed
es, l'Energie, l'Environnement et la Sant
e (ICPEES, UMR 7515), CNRS e Universit
e de Strasbourg, Strasbourg, France Laboratoire de Gestion des Risques et Environnement (GRE), Universit
e de Haute Alsace, Mulhouse, France c In'Air Solutions, 1 rue Blessig, 67000 Strasbourg, France a

b

a r t i c l e i n f o

a b s t r a c t

Article history: Received 19 June 2014 Received in revised form 2 August 2014 Accepted 7 August 2014 Available online

Cascade Impactor is a powerful sampling method to collect airborne particles as a function of their size. The 3-stages Cascade Impactor used in this study allowed to sample simultaneously particles with aerodynamic diameter Dae > 10 mm, 2.5 mm < Dae < 10 mm, 1 mm < Dae < 2.5 mm and Dae < 1 mm. Once collected individual concentrations of the 16 US-EPA priority Polycyclic Aromatic Hydrocarbons (PAHs) bound to particles were quantified for 8 different indoor environments located in Strasbourg area in France. All the heavy PAHs owning between 4 and 6 aromatic rings were detected in all of the 8 sampling sites. The total PAHs concentration varied from 0.44 to 2.09 ng m
3 for a low-energy building school and a smoking apartment, respectively. Results revealed also that high molecular weight PAHs were mainly associated to the finest particles. Our data are consistent with those measured elsewhere in European indoor environments. © 2014 Elsevier Ltd. All rights reserved.

Keywords: PAHs Cascade impactor Particles Indoor air quality HPLC-fluorescence

1. Introduction Indoor air quality has become a public health issue with wellestablished consequences. It's a very challenging subject because of the diversity of indoor pollutants. The insufficiency of air renewal, the abundance of primary emissions and both homogeneous and heterogeneous physico-chemical processes occurring in indoor environments explain the observed high concentrations (Forester and Wells, 2009; Weschler and Shields, 1997). Thus it is essential to determine the concentrations levels of the target species and the associated risks for health because it is known that people typically spend between 80 and 90% of their time indoor. Among the organic pollutants, Polycyclic Aromatic Hydrocarbons (PAHs) are compounds of increasing concern because they are broadly present in air. The American Environmental Protection Agency (US-EPA) has listed 16 of the most hazardous. One of the most famous is the Benzo[a]Pyrene (B[a]P) due to its carcinogenic properties so that it has been classified in group 1 by the International Agency for Research on Cancer (IARC). It is therefore often used as an appropriate marker of all the PAHs. Besides, the

* Corresponding author.
). E-mail address: [email protected] (S. Le Calve http://dx.doi.org/10.1016/j.envpol.2014.08.007 0269-7491/© 2014 Elsevier Ltd. All rights reserved.

European ambient air legislation (directive n 2004/107/CE) targets this PAH and recommends an annual maximum outdoor guideline value of 1 ng m
3. Indoors, PAHs are found among several matrixes such as gas phase, airborne particles, exposed surfaces or settled dust (Weschler and Nazaroff, 2010). Indoor sources of PAHs include residential heating systems, cooking (Zhu and Wang, 2003) and other activities as tobacco smoking (Castro et al., 2011; Fromme et al., 2004; Pey et al., 2013; Slezakova et al., 2009), incense or candle burning (Orecchio, 2011), etc. Infiltration of outdoor air indoors through ventilation systems is also a non-negligible source of indoor PAHs (Fromme et al., 2004). Various studies performed worldwide reported particle-bound PAHs concentrations values in the range of pg m
3eng m
3. PAHs concentrations are significantly influenced by smoking (Castro et al., 2011; Chuang et al., 1991; Pey et al., 2013; Slezakova et al., 2009), by car traffic or industrial emissions (Fischer et al., 2000; Li et al., 2005; Naumova et al., 2003), by cooking (Masih et al., 2010; Zhu and Wang, 2003) or by the effect of the heating and non heating season, i.e. winter and summer (Jung et al., 2010; Ohura et al., 2004) (see Table S1 in supplementary data). One European study simultaneously reported PAHs values for several of these indoor environments with homes, offices, restaurants, pubs, museum and librairies (Delgado-Saborit et al., 2009). More

C. Liaud et al. / Environmental Pollution 195 (2014) 64e72

recently, the particles and PAHs levels in schools are of great concern (Krugly et al., 2014). Additionally, several of these studies also measure outdoor PAHs concentrations because infiltration of outdoor air is one of the main vectors of indoor particles and therefore a source of PAHs (Delgado-Saborit et al., 2009; Dubowsky et al., 1999; Fromme et al., 2004; Krugly et al., 2014; Masih et al., 2010; Sangiorgi et al., 2013). For instance, Sangiorgi et al. have shown that indoor-to-outdoor concentration ratios (I/O) of PAHs were below 1 with values in the range 0.31e0.78 during the cold season and 0.73e0.98 during the warm season (Sangiorgi et al., 2013, see their table SM5). While numerous studies focused on bigger size particles (PM10, PM2.5) (Fischer et al., 2000; Fromme et al., 2004, 1998; Jung et al., 2010; Slezakova et al., 2009) or on particulate matter with no size fractionation (Cristale et al., 2012; Delgado-Saborit et al., 2009; Masih et al., 2010), a few studies have focused on lower size particles, i.e. PM1 who can penetrate into the respiratory system and especially the alveolar part (Lin et al., 2013; Sangiorgi et al., 2013). The main objective of this study was first to investigate indoor levels of particle-bound PAHs using the 3-stages cascade impactor air sampling coupled to an analytical method developed in a previous study (Liaud et al., 2014) and then to quantify the PAHs partitioning between the several size fractions, i.e. PM1, PM2.5 and PM10. For this, particles were collected in 8 different indoor environments in Strasbourg in France. In addition, the carcinogenic risk due to PAHs exposure in the investigated indoor environments was evaluated by using the B[a]P equivalent. 2. Materials and methods 2.1. Sampling locations The sampling campaigns were conducted from the 1st October to 4th November, 2013 in 8 different indoor environments around Strasbourg in France. The indoor environments were located at the city centre, in the suburbs of Strasbourg and in several rural places. Each sampling site was chosen with the aim to obtain data from various indoor environments. The characteristics of sampling locations are presented in Table 1. Four indoor locations (sites Rural 1, Rural 2, Rural 3 and Rural 4) were situated in rural zones (approx. 25 km far from Strasbourg). Three of these sites (sites Rural 1, Rural 2, Rural 3) were private housing and one possessed a fireplace as heating system (site Rural 2). However, the sampling room chosen in site Rural 2 was not in the living room where was the fireplace, because of the noise induced by the pump. Site Rural 4 was a newly built school classified as low energy building. This school was constructed with good air quality concern. The four other locations were situated in or near from the city of Strasbourg (276 400 inhabitants, 78 km2). Site Suburb 1 was situated in the suburbs (3 km from the city centre) near from a motorway. Site Suburb 2 was the kitchen of a restaurant which used electric stove for cooking. Site Urban 1 was a family house located near from the city centre of

65

Strasbourg with high-traffic density and close to tramway lines. The last site (site Urban 2) was a private apartment located in the city centre, near a highway exhibiting an intensive traffic; moreover the owner of the apartment was a smoker. The ambient temperature ranged between 20 and 24  C and the relative humidity varied in the range 40e60%. 2.2. Indoor particles sampling Single measurements were performed with a commercial manual 3-stages size fractionating cascade impactor from DEKATI (Impactor PM-10/PM-2.5/PM-1). Collected fractions corresponded to particles with aerodynamic diameter (Dae) in the ranges Dae >10 mm, 10 mm > Dae >2.5 mm, 2.5 mm > Dae >1 mm and a backup filter which allowed the collection of particles with Dae <1 mm. DEKATI PM-10 impactor operation is based on inertial classification and gravimetric analysis of the aerosol particles. This device classifies particles according to their aerodynamic diameter for 50% of efficiency (D50%) for each stage, explaining why bigger particles can be present in theoretical smaller fractions. D50% is given by the manufacturer with 2.8% of accuracy for each impaction stage. Samples were collected onto glass microfiber filter (GFF) (Whatmann, Ø 47 mm) and sizes were adapted to the calibrated collection plates (Ø 25 mm). The chemical analyses were performed on particles impacted on filters during 2e4 days. The sampling flow rate was set to 0.5 m3 h
1 allowing a total sampling air volume of 25e50 m3. Sampling details are presented in Table 1. Particulate matter (PM) masses were measured gravimetrically by subtracting the initial mean mass of the blank filter from the final mean mass of the same filter after sampling. The difference was then divided by the total air volume that passed through the filter to obtain mass concentration. Each filter was weighed 3 times and the mean result was then used for further calculations. The accuracy of the microbalance was 10 mg. After sampling filters were weighed to avoid any loss of PAHs compounds and then stored in Petri dished covered with aluminium foil, and kept in refrigerator (4  C) until they were further analysed (maximum 3 days after sampling). 2.3. Chemical analysis The extraction, analysis and Limits Of Detection (LOD) and Quantification (LOQ) of individual PAHs are described in detail elsewhere (Liaud et al., 2014) and are summarized in supplementary data (Table S3). Briefly, the particulate matter impacted on GFF (32 samples: 4 filters for each of the 8 sampling locations) was extracted with approximately 70 mL of acetonitrile (ACN) by means of an Accelerated Solvent Extractor. The extracts were then carefully filtered through a PVDF filter (0.45 mm) and reduced to 1 mL using a rotary evaporator (Büchi) at 45  C and 220 mbar. A gentle stream of nitrogen was finally used to concentrate the extracts in the range 100e150 mL where the exact volume was determined by weighing. Extracts were analysed using a High Performance Liquid Chromatography equipped with a Diode Array Detector and a Fluorescence detector (Thermo Fisher Scientific). Limits Of Quantification were in the range 0.05e0.47 mg L
1 corresponding to 0.75e7.05 pg m
3 for 20 m3 of pumped air. Average filter blanks (n ¼ 5) were subtracted to the PAHs masses obtained for field measurements.

3. Results & discussion The results obtained in this study are presented below and are compared with those focussing on PAHs measurements and

Table 1 Characteristics of the investigated 8 indoor environments around Strasbourg and sampling procedure. Urban Urban 1 Location Urban area Particularity of the sampling site Proximity of the tramway Type of indoor site Private house Indoor sampling location Open entrance

Suburban Urban 2

Suburb 1

Urban area City centre

Suburb Proximity of the motorway Private apartment Private apartment Unoccupied Open bedroom bedroom closed Natural Natural

Rural Suburb 2

Rural 1

Rural 2

Rural 3

Suburb One cooking activity Restaurant Open Kitchen

Rural Proximity from 2 farms Private house Living room

Rural Small town

Rural Small town

Rural Low energy building Private house Private house School Closed bedroom Living room Classroom

Natural

CMVRa

Natural

CMVb

Floor heating (Gas) No No Low Low 10 cm 10 cm 3.5

Ventilation type

Natural

Heating system during sampling period Presence of smokers Vehicle traffic intensity Height (approximate) of the sampling inlet Sampling period (days)

Floor heating (gas) Gas

Gas

Electric stove e

No High 1m

Yes Very high 10 cm

No Medium 10 cm

No Medium 1m

No Low 50 cm

wood burning fireplace No Low 50 cm

3.0

2.9

2.0

2.6

4.2

2.4

a b

Controlled Mechanical Ventilation system set to Relative Humidity (RH). Controlled Mechanical Ventilation system.

Rural 4

Double flow CMVb e

4.0

66

C. Liaud et al. / Environmental Pollution 195 (2014) 64e72

the air quality network ASPA which were about 21 mg m
3 (1e36 mg m
3) and 43 mg m
3 (3e102 mg m
3) for the same period, i.e. 1st Octobere5th November 2013. The kitchen of the restaurant with an all-electric equipment at the site Suburb 2 presented the highest value (19.6 mg m
3) with a huge quantity of fine particles since they represented 72% of the total mass concentration. This result is in accordance with the observations of Pey et al. (2013) who found that cooking activities in a cafeteria were a main particle source. In the smoker apartment located in the city centre of Strasbourg (site Urban 2), the total particles concentration of 11.1 mg m
3 was surprisingly relatively low and significantly lower than those found in other studies where values ranging from 37 to 452 mg m
3 for PM10 and from 34 to 440 mg m
3 in PM2.5 (Slezakova et al., 2009) in a smoker's apartment or of 148.0 mg m
3 in a cafeteria before the ban on smoking (Pey et al., 2013). However, in our case, our sampling material was installed in an unoccupied bedroom to prevent the noise from the pump and not in the main smoking room, i.e. the living room, which probably leads to underestimate the real particles concentrations. As shown in Fig. 1, the proportion of smaller particles, i.e. Dae <1 mm, reaches up to 100% for the site Rural 4 which is the lowenergy building school. A mechanical double flow ventilation system is indeed installed in this new school and is equipped with two types of filters according to the European standard EN 779:2012, i.e. with a filter class F7 for fresh air, efficient for fine particles (1 mm), and a filter class G4 for coarse particles (10 mm). G4 filters are adapted for both fresh air pre-filtration and extracted air filtration whereas class F7 filters are used for injected air. The absence of particles higher than 1 mm reveals the high effectiveness of the PM filtration system of the school. Consequently, the total PM was reduced to 7.5 mg m
3.

reported in the literature. Towards the collection efficiency of cascade impactors, the size distributions for PM and PAHs might be taken with caution. Faced with the multitude of data in the literature, our measurements are compared especially with those achieved in indoor air in Europe or alternatively with a few studies using a cascade impactor as sampling tools. Nevertheless, a few comparisons are performed with outdoor European measurements or with other indoor data collected in other continents (Asia, North America). The data used for comparison are summarized in the Table S1 of the supplementary data. 3.1. PM mass concentration Fig. 1 shows the Particulate Matter mass concentrations measured in all the sampling sites. Indoor PM concentrations are interestingly very low with values varying from 7.5 mg m
3 for the school (Rural 4) to 19.6 mg m
3 for the kitchen of a restaurant (Suburb 2). Except for both Suburb 2 and Rural 4, the PM mass concentrations measured in rural sites were surprisingly in the same order than those found in suburb and urban sites. In all samples, the collected mass of the finest particles, i.e. Dae <1 mm (PM1) ranges between 320 and 440 mg. This is sufficient towards the accuracy of 10 mg of the balance and significantly larger than other bigger sizes (see Fig. 1 and Table 2) where the collected mass was much more limited causing large uncertainties on PM2.5 and PM10 concentrations. Except for site Urban 1, other sites exhibit higher proportion of the finest particles with a minimum of 67% for site Rural 2 and a maximum of 100% for site Rural 4. Our total particles concentrations are consistent with those previously found in European non-smoking homes and offices (in units of mg m
3): 4.1e22.1 (PM1) and 6.9e33.8 (PM2.5) with average values equal to 12.1 and 18.1, respectively (Sangiorgi et al., 2013); 10.2e40 (PM2.5) and 11.3e46.5 (PM10) (Slezakova et al., 2009); 27e29 (Fromme et al., 2004); 4e78 (PM2.5) and 9e87 (PM10) (Fischer et al., 2000). Our reported values are also in agreement with those determined in the USA: averages values of 16.6 and 17.8 mg m
3 for 262 homes for non-heating and heating seasons, respectively (PM2.5) (Jung et al., 2010); average values of 13.4e17 mg m
3 (PM2.5) in non-smoking residences (Naumova et al., 2002, 2003). In Asian countries, indoor values were very different depending on the country but globally higher than European or American particle level (in units of mg m
3): 62.2 in PM10 and 36.2 in PM1 in Taïwan (Lin et al., 2013); in the range 82.1e171 mg m
3 in Guangzhou in China in PM2.5 (Li et al., 2005). In addition, our indoor values were globally lower than those from outdoor for both PM2.5 and PM10 monitored in Strasbourg by

3.2. Total PAH concentrations Table 2 reports the sum of total particulate PAHs concentrations determined in the 8 studied indoor environments. PAHs were detected in all of the 8 sampling sites with a total PAHs concentration varying from 0.44 to 2.09 ng m
3 (see also Table 2) for the low-energy building school (Rural 4) and the smoker's house (Urban 2), respectively. As observed for PM mass concentrations, the PAHs concentrations found in the rural sites were approximately in the same range than those measured in suburb and urban sites. The average values of total PAHs (range values in brackets) can be calculated for the different type of sites investigated in this work: 1.6 (1.1e2.1), 1.4 (1.0e1.8) and 1.3 (0.4e1.8) ng m
3 for urban, suburban and rural sites, respectively. Regarding the small differences observed above and the limited number of samples for each

-3

Particle concentration ( µg m )

25 20 15

Dae>10 µm 2,5
10 5

l3

l4 ra Ru

2 al

2

l1

ra Ru

Ru r

ra Ru

rb

rb

n

1

bu Su

bu Su

ba Ur

Ur

ba

n

1

2

0

Fig. 1. Particulate Matter mass concentrations (mg m
3) obtained in the 8 sampling sites and related to the collection plate and then the particulate size (Dae).

Table 2 Total and individual PAHs concentrations (pg m
3), mass concentrations evaluated for PM10, PM2.5 and PM1 and BaPeq values (ng m
3). PAHs compound

2 3

NAP ACY ACE FLU PHE ANT FLN PYR B[a]A CHR B[b]F B[k]F B[a]P DB[a,h]A B[g,h,i]P IND 1116 ± 289 0.126 14.6

4

5

6 Ʃ16 PAHs BaPeq(ng m
3) PM concentration (mg m
3) 2 3

4

5

6 Ʃ16 PAHs BaPeq(ng m
3) PM concentration (mg m
3) a

NAP ACY ACE FLU PHE ANT FLN PYR B[a]A CHR B[b]F B[k]F B[a]P DB[a,h]A B[g,h,i]P IND 1805 ± 489 0.167 10.5

Total PMa

PM10

PM2.5

PM1

Urban 1 e 161 ± 47 e 20 ± 6 161 ± 50 8±2 72 ± 20 97 ± 22 15 ± 3 31 ± 7 72 ± 16 32 ± 7 73 ± 16 21 ± 5 181 ± 43 171 ± 43 950

e 107 e 15 110 6 49 77 15 29 72 32 73 21 174 171 786

e 53 e 7 60 4 30 57 14 25 70 32 72 21 169 171 605

12.7

7.8

5.4

e e e 3 20 2 11 38 13 20 67 30 67 21 151 162 2087 ± 601 0.047 11.1

Rural 1 680 ± 193 129 ± 37 e 81 ± 25 241 ± 74 9±2 29 ± 8 45 ± 10 21 ± 5 34 ± 8 83 ± 19 41 ± 9 91 ± 20 43 ± 10 132 ± 31 148 ± 37 1319

402 78 e 48 139 5 27 38 19 31 83 40 90 43 128 148 929

173 53 e 26 75 2 14 25 17 26 81 38 88 41 124 145 565

10.5

10.5

8.2

e 31 e e e e e 14 13 21 74 34 81 39 119 138 1246 ± 347 0.087 16.1

Total PMa

PM10

PM2.5

PM1

Urban 2 e 24 ± 7 16 ± 4 52 ± 16 1282 ± 394 42 ± 11 261 ± 74 190 ± 44 8±2 11 ± 2 21 ± 5 14 ± 3 28 ± 6 7±2 83 ± 20 49 ± 12 1596

e 11 16 48 964 31 188 133 8 11 20 12 25 7 77 45 1106

e e 16 40 634 20 116 82 8 11 20 12 24 7 73 45 474

11.1

9.6

7.9

e e 7 19 190 5 37 25 8 11 20 11 22 7 66 45 1047 ± 275 0.11 14.7

Rural 2 e 12 ± 3 e 67 ± 20 604 ± 186 20 ± 5 91 ± 26 117 ± 27 13 ± 3 20 ± 4 21 ± 5 12 ± 3 35 ± 8 35 ± 8 98 ± 23 102 ± 26 992

e e e 54 450 14 55 84 13 20 21 12 34 35 98 102 758

e e e 36 307 8 22 51 11 20 21 12 34 35 98 102 496

13.3

12.6

10.9

e e e 14 146 2 e 17 7 10 21 11 32 35 98 102 1757 ± 421 0.374 11.9

Total PMa

PM10

PM2.5

PM1

Suburb 1 e e e 19 ± 6 325 ± 100 20 ± 5 102 ± 29 154 ± 35 13 ± 3 27 ± 6 103 ± 23 29 ± 7 62 ± 14 23 ± 5 84 ± 20 86 ± 21 957

e e e 17 259 15 102 139 13 27 103 29 62 23 84 86 729

e e e 9 143 9 60 90 13 27 95 29 62 23 84 86 479

14.7

13.9

12.7

e e e 3 26 4 15 38 13 21 83 29 59 22 80 86 1816 ± 463 0.229 19.6

Rural 3 e 66 ± 10 e 27 ± 8 137 ± 42 5±1 57 ± 16 115 ± 26 40 ± 9 66 ± 15 191 ± 43 84 ± 19 216 ± 48 90 ± 21 347 ± 83 316 ± 79 1645

e 33 e 22 107 4 45 101 38 61 189 83 215 90 338 316 1579

e 33 e 15 80 4 36 92 37 58 189 83 214 90 332 316 1422

11.4

11.4

10.5

e e e 11 57 3 26 79 33 50 179 79 203 85 313 303 435 ± 117 0.038 7.5

Total PMa

PM10

PM2.5

PM1

Suburb 2 e 117 ± 34 e 18 ± 5 279 ± 86 23 ± 6 207 ± 59 145 ± 33 33 ± 7 57 ± 13 190 ± 41 73 ± 17 141 ± 31 30 ± 7 256 ± 61 248 ± 62 1681

e 91 e 12 195 17 207 145 31 53 182 73 141 30 256 248 1400

e 57 e 9 103 11 125 98 29 43 177 73 141 30 256 248 1098

e 25 e 5 19 5 45 48 24 34 170 70 136 27 249 240

19.0

16.4

14.2

Rural 4 e e e 27 ± 8 146 ± 45 6±1 45 ± 13 46 ± 11 4±1 10 ± 2 29 ± 7 12 ± 3 19 ± 4 10 ± 2 41 ± 10 41 ± 10 388

e e e 25 124 5 33 35 4 10 29 12 19 10 41 41 269

e e e 9 55 2 17 20 4 10 29 12 19 10 41 41 229

7.5

7.5

7.5

e e e 7 38 2 7 10 4 10 29 12 19 10 41 41

C. Liaud et al. / Environmental Pollution 195 (2014) 64e72

Aromatic ring number

Sum of the PAHs concentrations on the 4 stages þ uncertainties.

67

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C. Liaud et al. / Environmental Pollution 195 (2014) 64e72

located in an urban place but with non-smoker inhabitants, is consistent. Comparison between a smoker apartment and a non smoker apartment in Portugal was performed by Slezakova et al. (2009). This latter show that PAHs mean concentration was 93% higher in the smoking place with a value of 97.2 ng m
3. Castro et al. (2011) found the same tendency with a total PAHs concentration 95% higher than that measured in the non-smoking place. In addition, the smoker apartment presents the highest proportion of PAHs associated to particles with Dae > 1 mm, even if the PM1 constituted the major part of the particles as illustrated in Figs. 1 and 2. From Fig. 3, it appears that high abundance of PHE leads to high proportion of total PAHs in particles with diameter larger than 1 mm. The site Urban 1 located in a high traffic road in Strasbourg exhibits a total PAHs content of only 1.11 ng m
3.

type of sites, the individual comparison of each site was more relevant. The Fig. 2 shows the total concentrations of 16 PAHs associated to airborne particles related to their aerodynamic diameter. Despite the small amount of particles collected on the two first plates (see Section 3.1), PAHs were successfully quantified. When considering the distribution of PAHs depending on the Dae of particles, Fig. 2 highlights that there is a high proportion of PAHs bound to fine particles with Dae <1 mm. This proportion ranges between 22.7 and 80.9% for the sites Urban 2 and Rural 3, respectively. The same tendency was observed in the literature (Castro et al., 2011; Mesquita et al., 2014; Miguel et al., 1998; Zhu et al., 2009). For instance, Zhu et al., 2009 found particulate PAHs mainly associated to PM2.5 (59e97%) while the proportion on PM2.5-10 and PM>10 ranged from 0 to 24%. Considering other PAHs concentrations values found in the literature, indoor environment in Strasbourg seems to be less exposed to PAHs pollution. Delgado-Saborit et al. (2011) reported total PAHs concentration in 81 homes and 30 offices in England and found geometric means of 1.37 and 1.50 ng m
3 for values ranging from below detection limit to 25 ng m
3 and from 0.03 to 17 ng m
3, respectively. In the same study, the 7 investigated restaurants showed higher concentrations with a geometric mean of 6.9 ng m
3 and values ranging between 4.3 and 15 ng m
3. Besides, Krugly et al. (2014) studied particulate phase PAHs in PM2.5 in 5 schools in Lithuania and found total PAHs mean values in the range 20.3e131.1 ng m
3. Several studies have simultaneously measured outdoor PAHs level with generally higher levels than indoors (Delgado-Saborit et al., 2011; Sangiorgi et al., 2013). The average urban outdoor annual concentration of total particle-bound PAHs reported by the air quality network ASPA located in Strasbourg was equal to 2.66 ng m
3 with values ranging between 0.33 and 8.94 ng m
3 in 2013. These latter are consistent with the European outdoor PAHs measurements reported in the literature but substantially lower (in units of ng m
3): 40.7e121.2 in outdoor air of schools during winter 2011/2012, Lithuania (Krugly et al., 2014); geometric means of 15 (3.1e414) in traffic roadsides and 8.3 (1.3e290) in background streets of England during winter and summer between 2006 and 2007 (Delgado-Saborit et al., 2011); a median of 2.5 ng m
3 with maximum value of 15.9 ng m
3 in Germany for the period winter/ spring 2000 (Fromme et al., 2004). Despite the chosen unoccupied room as sampling site, the smoking apartment exhibits, in this study, the higher PAHs concentration but the value of 2.09 ng m
3 does not reach the same range as others studies. However, the comparison of total PAHs concentrations between sites Urban 2 and Urban 1, which is also

3.3. Individual PAHs composition and size distribution Table 2 summarizes the concentrations of 16 individual PAHs determined in the particulate air samples. Concentrations of individual PAHs in PM10, PM2.5 and PM1 were derived from results obtained for each impaction plate. However, because of the collection efficiency of 50% for particles at each plate of the cascade impactor, PAHs concentrations determined by chemical analysis for each plate only give a good approximate distribution snapshot. Naphthalene which is usually mainly present in gas phase was only found at the site Rural 1 (see Fig. 3) at a surprisingly huge concentration level of 680 pg m
3 in particle phase whereas a tiny concentration of acenaphtene was measured in only one urban indoor environment (Urban 2). Meanwhile, acenaphtylene was measured in six of the eight air samples with concentrations varying in the range 12e161 pg m
3. All the other 13 PAHs were detected and quantified in all the indoor environments. The mean values calculated from the 8 studied sites for the 16 PAHs were the following (in units of pg m
3): 85 (NAP), 64 (ACY), 2 (ACE), 39 (FLU), 397 (PHE), 17 (ANT), 108 (FLN), 114 (PYR), 18 (B[a]A), 32 (CHR), 89 (B [b]F), 37 (B[k]F), 83 (B[a]P), 32 (DB[a,h]Ant), 153 (B[g,h,i]P) and 145 (IND). These average values were then used to calculate the concentrations of PAHs containing 3, 4, 5 or 6 rings (in units of pg m
3): 518 (3 cyles), 272 (4 cycles), 241 (5 cycles) and 298 (6 cycles). It is interesting to underline that other studies have already reported the relative low content of heavy PAHs compared to light PAHs in indoor environments (Chuang et al., 1991; Naumova et al., 2002). If we consider B[a]P which is the most dangerous PAH for health, its concentrations ranged from 19 to 216 pg m
3, for sites Rural 4 and Rural 3, respectively. These values are consistent with those measured elsewhere in European indoor environments or alternatively in USA (in units of pg m
3): 90 (n.d. - 2400) in homes and

-3

PAHs concentration ( pg m )

2500 2000 Dae>10 µm 2,5
1500 1000 500

3

2

4 al Ru r

al Ru r

al

1 al

Ru r

Ru r

b1

2

b2 ur Su b

ur Su b

an Ur b

Ur b

an

1

0

Fig. 2. Distribution of total PAHs concentration related to the impaction plate and then the particulate size (Dae) determined in the 8 sampling sites (pg m
3).

300

300 250

200

150

100

50

Suburb 1

250

200

150

100

50

Suburb 2

250

200

150

100

50

0 NA P AC Y AC E FL U PH E AN T FL N PY R B[a ]A CH R B[b ]F B[k ]F B[a DB ] P [a, h B[g ] A , h, i] P IN D

443,47

NA P AC Y AC E FL U PH E AN T FL N PY R B[a ]A CH R B[b ]F B[k ]F B[a DB ]P [a, h B[g ] A , h, i] P IN D

300

Urban 2 P AC Y AC E FL U PH E AN T FL N PY R B[a ]A CH R B[b ]F B[k ]F B[a DB ]P [a, h B[g ] A , h, i] P IN D

NA

-3

PAHs concentration (pg m )

50

-3

100

PAHs concentration (pg m )

150

-3

200

PAHs concentration (pg m )

NA P AC Y AC E FL U PH E AN T FL N PY R B[a ]A CH R B[b ]F B[k ]F B[ a DB ] P [a, h B[g ] A , h, i] P IN D

-3

PAHs concentration (pg m ) 250

Dae>10µm 2,5
-3

P AC Y AC E FL U PH E AN T FL N PY R B[a ]A CH R B[b ]F B[k ]F B[a DB ] P [a, h B[g ] A , h, i] P IN D

NA

-3

PAHs concentration (pg m ) 300

Urban 1

PAHs concentration (pg m )

NA P AC Y AC E FL U PH E AN T FL N PY R B[a ]A CH R B[b ]F B[k ]F B[a ] DB P [a, h B[g ] A , h, i] P IN D

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NA P AC Y AC E FL U PH E AN T FL N PY R B[a ]A CH R B[b ]F B[k ]F B[ a DB ]P [a, h B[ g ] A ,h, i] P IN D

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C. Liaud et al. / Environmental Pollution 195 (2014) 64e72

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Fig. 3. PAHs concentration distribution (pg m
3) for each PAH depending on the collection plate and then the particulate size (Dae) in the urban suburb and rural sites.

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90 (n.d. - 1250) in offices (Delgado-Saborit et al., 2011), 100 in a cafeteria after the smoking ban (Pey et al., 2013), 573 (131e1510) in non-smoking place (Castro et al., 2011), 612 (107e1020) also in non-smoking place (Slezakova et al., 2009), between 90 and 250 ng m
3 in a street-side non-smoker living room (Fromme et al., 2004), 170 (30e390) and 490 (150e1120) in homes close to low and high-traffic density, respectively (Fischer et al., 2000), from 2.7 to 560 in indoor residence in 3 US cities (Naumova et al., 2003, 2002), 150e230 (Jung et al., 2010). In addition, the indoor B[a]P concentrations found in the 8 environments are quite lower than those found outdoor in Strasbourg during the same sampling period with 270 (170e510) pg m
3 (Air quality network ASPA). In Fig. 3 are represented individual PAHs concentrations depending on the Dae for the urban, suburban and rural indoor environments. Interestingly, as shown in Fig. 3, the distribution of PAHs is related to particle size so that high molecular weight PAHs were mainly associated to the smallest particles found in the 2 last filters as observed in previous studies (Kavouras et al., 1998; Slezakova et al., 2009; Zhu et al., 2009). If we consider separately the PAHs with 2, 3, 4, 5 and 6 aromatic rings in all the sampling sites, the average percentages of PAHs bound to finest particles (PM1) are as follows: 0% (2 cycles), 16% (3 cycles), 33% (4 cycles), 93% (5 cycles), 94% (6 cycles). These calculated values confirm the huge affinity of high molecular weight PAHs, typically those owning 5 or 6 aromatic cycles, for PM1. As illustrated in Fig. 3, again, the low energy-built school (the site Rural 4), shows high filtration performances since PAHs contents are low. The site Rural 1 is strongly marked with high naphthalene content. Despite this compound is preferentially in gas phase, the use of mothballs and insect repellent in this house can explain the presence of naphthalene on the filters (Jia and Batterman, 2010). Note that naphthalene is absent in PM1. Sites Urban 2 and Rural 2 have high phenanthrene content (1282 and 604 pg m
3, respectively) with respect to anthracene (see Fig. 3 and Table 2) which can be due to combustion at low temperature. This difference between PHE and ANT content is observed in all sites but the gap is lower. Indeed these two compounds are isomers and phenanthrene is more thermodynamically stable than anthracene resulting in preferential formation of phenanthrene at low temperature (Yunker et al., 2002). These PAHs signature could be explained by the fact that Urban 2 is the smoker apartment while Rural 2 used a closed wood fireplace for heating during sampling. In addition, another explanation would be that sites Urban 2 and Rural 2 (and Suburb 1 and Suburb 2 to a lesser extent) shows similar profiles as those observed from car traffic. Indeed, phenanthrene, fluoranthene and pyrene are essentially emitted by diesel (Ravindra et al., 2008; Westerholm et al., 2001). By comparison to other rural sites, the high phenanthrene content at site Rural 2 could be explained by the natural ventilation while other rural sites possessed a mechanically controlled ventilation system. The comparison of both suburban sites highlights the strong influence of cooking activity in the restaurant because the concentrations of individual PAHs in site Suburb 2 are twice higher than those measured in the site Suburb 1. PAHs emissions from cooking were reported in the literature (Delgado-Saborit et al., 2011; Zhu and Wang, 2003) but the values determined in our study are significantly lower probably due to the use of electric equipment in the kitchen. In addition, during the sampling in site Suburb 2, cooking activity represented 13% of sampling duration, i.e. about 8 h, which could explain why concentrations are relatively low. Besides, emissions from different cooking practices such as boiling, frying or broiling, are responsible to different PAH emissions (Zhu and Wang, 2003). Moreover, this study compared several kitchens and found that a majority of 3e4 rings PAHs were

present in commercial kitchens while 2e3 rings PAHs were mainly present in domestic kitchens. In agreement with this observation, our study shows 3e4 rings PAHs were the main PAHs in air. For instance, concentrations of B[a]P, which is here chosen as an indicator of cooking activities, were found to be (in units of pg m
3): 256 (this work), 160 (40e790) (Delgado-Saborit et al., 2011), 150 000e440 000 in commercial kitchen and 6 100e24 000 in domestic kitchen (Zhu and Wang, 2003), 13 100e13 600 in urban home and road home kitchen (Masih et al., 2010). In the restaurant studied in this work, the high molecular weights PAHs were the most present especially in fine particles (Dae < 1 mm) (see Fig. 3). 3.4. Risk assessment In order to express the carcinogenic risk of the 8 sampling places due to PAHs exposure, the B[a]P equivalent factor (BaPeq) was evaluated and results are reported in Table 2. This factor is based on the PAHs concentrations determined with sampling followed by analysis and on a Toxic Equivalency Factor (TEF) which estimates the carcinogenic potency of PAHs to relative potency of B[a]P. These factors have been determined by numerous studies and we choose the most used approach to assess PAHs carcinogenic potential: the (Nisbet and LaGoy, 1992) version modified by Malcolm and Dobson (1994). This method used all the TEFs values from Nisbet and LaGoy except for DB[a,h]A which TEF value is 1 instead of 5. The TEFs values are reported in Table S2 in the supplementary data. The BaPeq is derived from Equation (1) in order to express the level of carcinogenicity of the mixture relative to B[a]P:

BaPeq ¼

16 X

½PAHi  TEFi

(1)

i¼1

where i is one of the 16 priority PAHs. This formula is built on 2 assumptions: 1) the impact of individual PAHs on animals is the same on humans, 2) the risks of individual PAHs is additive and so the sum of the individual risks is representative of the risk of the exposure to the entire PAHs mixture. In the investigated sampling sites, the evaluated BaPeq ranges between 0.038 and 0.374 ng m
3 for the sites Rural 4 and Rural 3, respectively. These values are all below the European guideline of 1 ng m
3 confirming the low PAHs contamination of these French indoor environments. Even if the outdoor concentrations of BaP are slightly higher than those found indoors, the main contribution to the total human exposure could be the indoor environments since people spent their major part of time indoors. However, contribution of outdoor concentrations is not negligible since they influence the indoor levels depending on the air exchange rate. Here again, our BaPeq values are lower than those found in others studies: 1.20e50.8 ng m
3 in schools in Lithuania (Krugly et al., 2014); 0.2e10.7 ng m
3 with candle burning emissions (Orecchio, 2011); 0.48 ng m
3 indoors and 2.83 ng m
3 for Environment Tobacco Smoking (ETS) (Delgado-Saborit et al., 2011); 1.70 ng m
3 in Japan (Ohura et al., 2004). 4. Conclusion This study shows that 3-stages cascade impactor is a useful sampling method which can be applied to investigate both particulate and PAHs size distribution in indoor environments. This technique was applied to 8 sampling sites in the vicinity of Strasbourg in order to derive PM10, PM2.5 and PM1 mass concentrations and then PAHs concentrations in one sampling step. Concerning PM concentrations, in all samples, the proportion of fine particles, i.e. Dae <1 mm, was larger than other bigger sizes

C. Liaud et al. / Environmental Pollution 195 (2014) 64e72

which were only given as estimations. The kitchen of the restaurant with all-electric equipment was identified as the main indoor PM source with a huge quantity of fine particles. The low-energy building school presented very low PM concentration revealing the effectiveness of the PM filtration system. The analysis of particle-bound PAHs revealed that PAHs were present in every sampling place and that the main part was bound to fine particles (PM1). Although low molecular weight PAHs are mainly in gas phase, some of them were nevertheless detected. Most of the probable human carcinogenic PAHs which are associated with particulate matter, were detected in each sampling place and our values were consistent with those measured elsewhere in European environments. Evaluated BaPeq values were below the European guideline of 1 ng m
3 confirming the low PAHs contamination of these indoor environments. Finally, this new approach using a relative short sampling time could be extended to future indoor field measurements performed for several weeks or months in order to observe temporal variations with a typical time resolution of 2e4 days. In addition these observations could be conducted simultaneously in both outdoor and indoor environments to investigate the influencing factors. Besides, more indoor air environments should be investigated. Acknowledgement Financial support for this work has been provided by the French Ministry of Environment and ADEME through the PRIMEQUAL 2 program (Project MERMAID). This work was also supported by the region of Alsace and the REseau Alsace de Laboratoires en
nierie et Sciences pour l'Environnement (REALISE). We also Inge acknowledge the air quality network ASPA for providing available data concerning outdoor PM concentrations in Strasbourg city: Information source: ASPA TD 13100801 and ASPA 14020702- TD. Appendix A. Supplementary data Supplementary data related to this article can be found at http:// dx.doi.org/10.1016/j.envpol.2014.08.007. References Castro, D., Slezakova, K., Delerue-Matos, C., Alvim-Ferraz, M., da, C., Morais, S., Pereira, M., do, C., 2011. Polycyclic aromatic hydrocarbons in gas and particulate phases of indoor environments influenced by tobacco smoke: levels, phase distributions, and health risks. Atmos. Environ. 45, 1799e1808. http:// dx.doi.org/10.1016/j.atmosenv.2011.01.018. Chuang, J.C., Mack, G.A., Kuhlman, M.R., Wilson, N.K., 1991. Polycyclic aromatic hydrocarbons and their derivatives in indoor and outdoor air in an eight-home study. Atmos. Environ. B Urban Atmos. 25, 369e380. http://dx.doi.org/10.1016/ 0957-1272(91)90008-3. Cristale, J., Silva, F.S., Zocolo, G.J., Marchi, M.R.R., 2012. Influence of sugarcane burning on indoor/outdoor PAH air pollution in Brazil. Environ. Pollut. 169, 210e216. http://dx.doi.org/10.1016/j.envpol.2012.03.045. Delgado-Saborit, J.M., Aquilina, N.J., Meddings, C., Baker, S., Vardoulakis, S., Harrison, R.M., 2009. Measurement of personal exposure to volatile organic compounds and particle associated PAH in three UK regions. Environ. Sci. Technol. 43, 4582e4588. http://dx.doi.org/10.1021/es9005042. Delgado-Saborit, J.M., Stark, C., Harrison, R.M., 2011. Carcinogenic potential, levels and sources of polycyclic aromatic hydrocarbon mixtures in indoor and outdoor environments and their implications for air quality standards. Environ. Int. 37, 383e392. http://dx.doi.org/10.1016/j.envint.2010.10.011. Dubowsky, S.D., Wallace, L.A., Buckley, T.J., 1999. The contribution of traffic to indoor concentrations of polycyclic aromatic hydrocarbons. J. Expo. Anal. Environ. Epidemiol. 9, 312e321. Fischer, P.H., Hoek, G., van Reeuwijk, H., Briggs, D.J., Lebret, E., van Wijnen, J.H., Kingham, S., Elliott, P.E., 2000. Traffic-related differences in outdoor and indoor concentrations of particles and volatile organic compounds in Amsterdam. Atmos. Environ. 34, 3713e3722. http://dx.doi.org/10.1016/S1352-2310(00) 00067-4. Forester, C.D., Wells, J.R., 2009. Yields of carbonyl products from gas-phase reactions of fragrance compounds with OH radical and ozone. Environ. Sci. Technol. 43, 3561e3568.

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