(Revised MS: HAZMAT-D-07-02616) 1
2
Characterization of PAHs exposure in workplace atmospheres of a sinter plant and 3
health-risk assessment for sintering workers 4
5
Yuan-Chung Lin1,2,3, Wen-Jhy Lee3,4, Shui-Jen Chen4,5, 6
Guo-Ping Chang-Chien1,2, Perng-Jy Tsai4,6* 7
8
1
Department of Chemical and Materials Engineering, Cheng Shiu University, 9
Kaohsiung County 833, Taiwan. 10
2
Super Micro Mass Research & Technology Center, Cheng Shiu University, 11
Kaohsiung County 833, Taiwan. 12
3
Department of Environmental Engineering, National Cheng Kung University. 13
1, University Road, Tainan 70101, Taiwan 14
4
Sustainable Environment Research Center, National Cheng Kung University. 1, 15
University Road, Tainan 70101, Taiwan. 16
5
Department of Environ mental Science and Engineering, National Pingtung University of 17
Science and Technology. 1, Shieh-Fu Rd, Nei Pu, Pingtung 91201, Taiwan, 18
6
Department of Environmental and Occupational Health, Medical College, National Cheng 19
Kung University. 138, Sheng-Li Road, Tainan 70428, Taiwan. 20
21 22 23
*Correspondence author: Perng-Jy Tsai. Department of Environmental and Occupational 24
Health, Medical College, National Cheng Kung University. 138, Sheng-Li Road, Tainan 25
704, Taiwan. Tel.: +886-6-2088390; Fax: +886-6-2752484; E-mail address: 26
pjtsai@mail.ncku.edu.tw (P.-J., Tsai) 27
Abstract 28
This study first measured concentrations of polycyclic aromatic hydrocarbons (PAHs) 29
in four selected workplace atmospheres, including the raw materials inlet, sintering grate, 30
rough roll shredder and control room, and the outdoor environment of a sinter plant. Then, 31
PAHs exposures and their resultant health-risks were assessed for sintering workers. We 32
found that total PAH concentrations of the three selected sintering process areas were 33
higher than that of the control room. The above results could be explained by the filtration 34
effect of the air conditioning device installed inside the control room. PAH homologue 35
distributions of the three selected sintering process areas were significantly different from 36
that of the outdoor environment suggesting that PAHs found in the sintering workplace 37
atmospheres were mainly contributed by process fugitives. Total PAH exposure levels were 38
lower than the current permissible exposure limits, thus revealing that sintering workers are 39
not a high risk group for long-term effects attributable to PAHs. Moreover, the lung cancer 40
risks associated with the above PAH exposures were lower than the significant risk level 41
defined by US Supreme Court further confirming that their exposures could be acceptable 42
at this stage. 43
Keywords: Polycyclic aromatic hydrocarbons, Sinter plant, Process fugitives, Exposure 44
assessment, Health risk assessment 45
1. Introduction 46
It is known that several polycyclic aromatic hydrocarbons (PAHs) are mutagenic 47
and/or carcinogenic in rodents, and some of them are human potential carcinogens [1]. 48
PAHs can be generated from many human activities, such as industrial production, 49
transportation, and waste incineration. In principle, the mechanisms associated with the 50
generation and/or depletion of PAHs in the high-temperature combustion process followed 51
three major pathways, including pyrosynthesis [2], direct emission of unburned fuel [3], 52
and thermal destruction of fuel components [4]. For iron and steel industries, PAHs are 53
released from coke manufacturing, sintering, iron making, casting, molding, cooling, and 54
steel making processes [5]. PAHs emitted from iron and steel industries has been 55
recognized as the second major source in Norway (accounting for 12% of the yearly total 56
PAH emission) [6]. Intensive studies have been conducted to investigate PAH emissions 57
from the stacks of various manufacturing processes in iron and steel industries [7]. 58
However, measurements of process fugitive PAH concentrations in workplace atmospheres 59
have been focused mainly on coke ovens [811]. To the best of our knowledge, PAHs 60
concentrations in sinter plant workplaces and their resultant health-risk impact on sintering 61
workers have never been reported. 62
To assess health risks associated with PAH exposures, it is important to know the total 63
carcinogenic potency arising from the exposures of various PAH compounds. In principle, 64
the carcinogenic potency of a given PAH compound can be assessed according to its 65
benzo[a]pyrene equivalent concentration (BaPeq). Calculating the BaPeq concentration for a
66
given PAH compound requires the use of its toxic equivalent factor (TEF; using 67
benzo[a]pyrene as a reference compound) to adjust its original concentration [12-14]. 68
Among the available TEFs lists, the one established by Nisbet and LaGoy in 1992 has been 69
demonstrated to best reflect the actual state of knowledge of the toxic potency of each 70
individual PAH species [14]. By using the TEF list the carcinogenic potency of total PAHs 71
(total BaPeq) can be determined as the sum of BaPeq concentrations of the 21 selected PAH
72
compounds. 73
For estimating the lung cancer risk associated with inhalatory PAH exposures, the 74
World Health Organization (WHO) has suggested a unit risk of 8.7 ×10-2 (µg m-3)-1 for the 75
lifetime (=70 years) PAH exposure, assuming one was exposed to BaP concentration of 1 76
µg m-3 [15]. It is worth noting that the above unit risk was proposed for lifetime exposure, 77
therefore, it has been adopted for assessing the exposure of general adults to the ambient 78
atmospheric PAHs [16]. For occupational exposure, Pott established a relationship between 79
BaP exposure and lung cancer risk [17], based on a data bank provided by an 80
epidemiological study conducted by Redmond et al. [18]. He suggested the unit risk of 7.0 81
×10-2 (µg m-3)-1 for a 25-year occupational PAHs exposure with the averaged BaP 82
concentration of 1 µg m-3. By using the same data bank, the US Environmental Protection 83
Administration [19], however, suggested a different unit risk of 6.4 ×10-4 (µg m-3)-1 for 84
PAHs exposure based on its total PAH content (expressed as the benzene soluble fractions). 85
Since a recent study has indicated BaP could be a better indicator than total PAH content 86
on characterizing the carcinogenic potency of PAHs [20], the unit risk suggested by Pott in 87
1985 has been used in our previous study [21]. 88
In this study, static air samplings were conducted in the above mentioned four 89
workplaces to characterize PAH fugitive emissions from the sintering process. 90
Time/activity patterns for workers of different job titles were recorded according to our 91
field observation. By combining the above two types of information workers’ PAH 92
exposure levels were assessed and their resultant health risks were estimated. 93
2. Materials and Methods 94
2.1. The selected sintering process 95
One sinter plant located in southern Taiwan, with a selective catalytic reduction (SCR) 96
air pollution control device, was selected in this study. For the selected sintering process, it 97
first involves the mixing of iron ore fines, iron-bearing recovery materials (such as 98
iron-bearing dusts and slag), and fluxes (lime or dolomite) with a ~5 % finely divided fuel, 99
such as coke breeze or anthracite. The mixture is then placed on a traveling grate to form a 100
sintering bed. The traveling grate resembles an endless loop of a conveyor belt, forming a 101
shallow trough with small holes in the bottom. The bed is ignited by passing under an 102
ignition burner which is fired with natural gas and air. During the ignition process, the air is 103
pulled down through the bed as the grate moves slowly toward the discharge end. As the 104
coke fines burn in the bed, the generated heat sinters/or fuses the fine particles. The 105
temperature of the bed is around 1,300 to 1,500 ºC. Mean production rates are 20 to 40 106
metric tons m-2 d-1 depending upon the characteristics of the ore materials and the sintering 107
conditions [22]. Typical operation conditions for the sintering process have been described 108
in more details elsewhere [23-24]. For sinter plant workers, they are required to perform 109
their work tasks at the nearby of the raw materials inlet, sintering grate, rough roll shredder, 110
and control room. 111
112
2.2. Sampling strategy and worker’s time/activity pattern 113
Three sampling sites located approximately 2 m away from the raw materials inlet (Site 114
#1), sintering grate (Site #2), and rough roll shredder (Site #3) were selected to characterize 115
PAH concentrations in the sintering workplaces of the selected sinter plant. For the selected 116
sinter plant, the air introduced to the control room (located at the end of the sintering grate) 117
was directly drawn from the workplace atmosphere of the sinter plant but was filtered by an 118
air conditioner. Static air samplings were also conducted in the control room (Site #4) in 119
order to characterize fugitives transferring from the sintering zone to the control room. The 120
location of the above sampling sites in the selected sintering plant are shown in Figure 1. 121
Field samplingswere also conducted on the outdoor environment located at the upwind side 122
of the selected sinter plant (Site #5) for comparisons. All air samples were colleted by using 123
a high-volume PS-1 sampler (Greaseby Anderson, GA). This sampler was equipped with a 124
quartz-fibre filter to collect PAHs of the particle phase, and followed by a XAD-16 125
cartridge for collecting PAHs of the gas phase. To avoid effluent stream from PS-1 dilute 126
the total suspended particle (TSP) and PAH concentration in control room, the effluent gas 127
from PS-1 sampler was discharged to the outside of the control room. The sampling flow 128
rate was specified at ~0.18 m3 min-1. Each sample was collected continuously for ~24 hrs 129
(i.e., sampling volume = ~250 m3). 130
The time/activity patterns of the four selected groups sintering workers were recorded 131
based on our field observation (Table 1). Group A (i.e., raw material charging workers) on 132
average stayed at Site #1 (raw materials inlet) and Site #4 (control room) for 1.67 hr and 133
6.33 hr, accounting for 20.8% and 79.2% of their total work time (8hr), respectively. 134
Group B (i.e., sintering grate workers) on average stayed at Site #2 (sintering grate) and 135
Site #4 for 2.5 hr and 5.5 hr, accounting for 31.2% and 68.8% of their total work time, 136
respectively. Group C (i.e., shredding workers) on average stayed in Site #3 (rough roll 137
shredder) and Site #4 for 3.0 hr and 5.0 hr, accounting for 37.5% and 62.5% of their total 138
work time, respectively. Group D (i.e., sintering process engineers and supervisors) on 139
average stayed in Site #1, Site # 2, Site #3 and Site #4 for 1.33, 1.33, 1.33 and 4.0 hr, 140
accounting for 16.7%, 16.7%, 16.7% and 50.0% of their total work time, respectively. 141
142
2.3. PAH analysis 143
For PAH analysis, each collected sample (including particulate and gaseous PAH 144
samples) was extracted in a Soxhlet extractor with a mixed solvent (n-hexane and 145
dichloromethane; vol/vol, 1:1; 500 mL each) for 24 hrs. The extract was then concentrated 146
by nitrogen (N2), cleaned up by sodium sulfate and re-concentrated to exactly 1.0 mL by N2.
147
PAH contents were determined using a Hewlett-Packard (HP) gas chromatograph (GC) (HP 148
6890N; Hewlett-Packard, Wilmington, DE, USA) with a mass selective detector (MSD) 149
(HP 5973) and a computer workstation (Aspire C500; Acer, Taipei, Taiwan). This GC/MSD 150
was equipped with a capillary column (HP Ultra 2, 50 m x 0.32 mm x 0.17 μm) and an auto 151
sampler (HP-7683). It was operated under the following conditions; injection volume of 1 152
μL, splitless injection at 310°C, an ion source temperature of 310°C, an oven from 50 153
to100°C at 20°C min-1; from 100 to 290°C at 3°C min-1; and held at 290°C for 40 min. The 154
masses of primary and secondary ions of PAHs were determined in scan mode using pure 155
PAH standards. PAHs were qualified in the selected ion monitoring (SIM) mode [25-29]. 156
The PAH homologues grouped by the number of rings are naphthalene (Nap) for 157
2-ring, acenaphthylene (AcPy), acenaphthene (Acp), fluorine (Flu), phenanthrene (PA), and 158
anthracene (Ant) for 3-ring, fluoranthene (FL), pyrene (Pyr), benzo[a]anthracene (BaA), 159
and chrysene (CHR) for 4-ring, cyclopenta[c,d]pyrene (CYC), benzo[b]fluoranthene (BbF), 160
benzo[k]fluoranthene (BkF), benzo[e]pyrene (BeP), benzo(a)pyrene (BaP), perylene (PER), 161
dibenzo[a,h]anthracene (DBA), benzo[b]chrycene (BbC) for 5-ring, 162
indeno[1,2,3,-cd]pyrene (IND), benzo[ghi]perylene (Bghip) for 6-ring, and coronene (COR) 163
for 7-ring. The GC/MSD was calibrated with a diluted standard solution of 16 PAH 164
compounds (PAH mixture-610M; Supelco, Bellefonte, PA, USA) plus five additional 165
individual PAHs obtained from Merck (Darmstadt, Germany). Ten consecutive injections 166
of a PAH 610-M standard yielded an average relative standard deviation of the integrated 167
GC/MSD area of 8.02 % (range = 5.45 % to 10.33 %). 168
In this study, two internal standards (phenanthrene-d10 and perylene-d12) were used 169
to check their response factors, the recovery efficiencies for PAHs analysis and to 170
determine final concentrations. The recovery efficiencies of 21 individual PAHs and these 171
two internal standards were determined by processing a solution containing known PAH 172
concentrations through the same experimental procedure used for the samples. Recovery 173
efficiency was measured via analyzed mass of PAH divided by input mass of known PAH. 174
This study showed the recovery efficiencies for the 21 PAH compounds range from 0.795 175
to 0.972, with an average value of 0.881. The recovery efficiencies of two internal 176
standards (phenanthrene-d10 and perylene-d12) were between 85.7% and 93.5 and were 177
fairly constant. The recovery efficiencies of these two internal standards (phenanthrene-d10 178
and perylene-d12) were averaged and used for the quantification. This action will control 179
the analysis error to be less than 15%, which guarantees the reported data of this study 180
being at an excellent level. Analyses of field blanks, including aluminum foil, glass fiber 181
filter and an PUF/XAD-16 cartridge, revealed no significant contamination (GC/MSD 182
integrated area < detection limit). 183
184
2.4. Data analysis 185
In this study, the total-PAH concentration represents the sum of the concentrations of 186
21 PAH compounds for each collected sample. PAHs were grouped into three categories 187
based on their molecular weights, including low molecular weight PAHs (LMW-PAHs, 188
containing two- and three-ringed PAHs), middle molecular weight PAHs (MMW-PAHs, 189
containing four-ringed PAHs), and high molecular weight PAHs (HMW-PAHs, containing 190
five- to seven-ringed PAHs). 191
In this study, the carcinogenic potencies associated with PAH emissions to each 192
workplace atmosphere were also determined. Here, the carcinogenic potency of a given 193
PAH compound was assessed according to its benzo[a]pyrene equivalent concentration (i.e., 194
BaPeq) by using the TEFs list established by Nisbet and LaGoy in 1992 [14]. The
carcinogenic potency of total PAHs (i.e., total BaPeq) was determined as the sum of BaPeq
196
concentrations of the 21 selected PAH compounds. To assess workers’ excessive lung 197
cancer risks associated with a 25-yr occupational exposure, the unit risk suggested by Pott 198
in 1985 (=7×10-5 (BaPeq ng m-3) -1) was used in the present study [17]. This is mainly 199
because BaP is a better indicator than total PAH content on characterizing the carcinogenic 200
potency of PAHs [20]. 201
All measured and estimated concentrations were presented in their means standard 202
deviation (SD). Statistical significance was examined by using the t-test. 203
3. Results and Discussion 204
3.1. TSP concentrations in sintering workplaces and the outdoor environment 205
Table 2 shows the mean total suspended particle (TSP) concentrations of the four 206
selected workplaces and the outdoor environment of the selected sinter plant. For the four 207
selected workplaces, the highest TSP was found at Site #1 (=2690 μg Nm-3), which was 208
considered due to dust emissions from the raw material charging process. The second and 209
third highest TSP were found at Site #2 and Site #3 (=2130 and 1600 μg Nm-3, 210
respectively), bur their concentrations were much lower than that of Site #1 (p<0.05). This 211
might be because the strong airflow was pulled down through the sintering bed resulting in 212
less fugitive TSP emitted into the sintering zone. TSP concentrations in Site #1, Site #2 and 213
Site #3 were 18.4, 14.6 and 10.9 times in magnitude higher than that in Site #4 (=146 μg 214
Nm-3) (p<0.05). This might be explained either by the location of the control room being 215
far away from the sintering process, or by the filtration efficiency (TSP reduction fraction 216
>95%) of the air conditioning device used in the control room. The permissible TSP 217
concentration in workplace environment in Taiwan is 10,000 μg Nm-3, which was 218
significantly higher than that of Site #1Site #4 (p<0.05). Nevertheless, it should be noted 219
that the concentrations found in Site #1Site #3 were still higher than that of the outdoor 220
environment (i.e., Site #5 =143 μg Nm-3) (p<0.05). The above result suggests that TSP 221
concentrations found in the sintering process areas were mainly contributed by the process 222
fugitives, rather than those transported from the outdoor environment. 223
224
3.2. Characterization of PAH concentrations in sintering workplaces and the outdoor 225
environment 226
Table 3 shows the mean PAH concentrations (gas- + particle-phase) of the four 227
selected workplaces and the outdoor environment of the sinter plant. For the mean total 228
PAH concentrations, we found that Site #2 (30.4 μg Nm-3) was significantly higher than 229
that of Site #1 (17.9 μg Nm-3) and Site #3 (16.3 μg Nm-3) (p<0.05), which was considered 230
due to molten process in the furnace. The concentrations found in the above three selected 231
sintering zone workplaces were significantly higher than that of the Site #4 (8.37 μg Nm-3) 232
(p<0.05). The relatively low total PAH concentrations found in the Site #4 (i.e., control 233
room) could be explained again either by its location being far away from the sintering 234
zone, or the filtration effect of the air conditioning device used in the control room. 235
Moreover, we also found that the PAH concentrations obtained from the sintering zones 236
(Site #1Site #3 =16.3 30.4 μg Nm-3) were much higher than that of outdoor environment 237
(Site #5 = 7.42μg Nm-3) (p<0.05). The above results further confirmed that PAHs found in 238
the workplace atmospheres could be mainly contributed by sintering process fugitives, 239
rather than that transported from the outdoor environment. 240
Regarding the measured total BaPeq concentrations (i.e., gas- + particle-phase), the
241
concentration found in the Site #2 (0.16 μg Nm-3) was higher than those found in Site #1 242
and Site #3 (0.12 and 0.13 μg Nm-3, respectively) (p<0.05). The pattern was similar to that 243
found in the corresponding total PAH concentrations, since the above three selected 244
sampling sites shared with similar PAH homologue distributions. Finally, total BaPeq
concentrations found in sintering zone workplaces (i.e., Site #1, Site #2, and Site #3) were 246
much higher than that of the Site #4 (0.040 μg Nm-3) (p<0.05). The above results suggest 247
that the isolation of the control room and the ventilation measures had a useful impact on 248
PAHs exposure profile, especially by lowering the concentrations of carcinogenic species. 249
Table 3 also shows the PAH homologue distributions of the 5 selected sampling sites. 250
We found the fractions of LMW-, MMW-, and HMW-PAHs in total-PAHs were quite 251
similar among Site #1 (86.5%, 9.52%, and 4.01%, respectively), Site #2 (86.7%, 9.60%, 252
and 3.71%, respectively), and Site #3 (86.3%, 8.53%, and 5.16%, respectively). The above 253
results again suggests PAHs found in the sintering zone were of the same nature (i.e., 254
emitted from the sintering process with a similar coagulation effect due to their low 255
concentrations). On the other hand, a very different pattern was found in Site #4 (91.4%, 256
6.09%, and 2.51%, respectively). Less fractions in both MMW- and HMW-PAHs found in 257
Site #4 could be because less particle-phase PAHs were found in the control room, 258
considering both MMW- and HMW-PAHs were mainly presented in particle-phase due to 259
their low volatile characteristics. Finally, a very different pattern was found in the outdoor 260
environment (79.5%, 16.4%, and 4.18%, respectively) further confirmed our previous 261
inference: PAHs found in the workplace atmospheres were mainly contributed by process 262
fugitives, rather than those transported from the outdoor environment. 263
3.3 Gas- and particle-phase PAHs containing in total PAH and total BaPeq 264
concentrations in the workplace atmospheres 265
Table 4 shows gas- and particle-phase PAHs containing in total PAH and total BaPeq
266
concentrations for samples collected from the workplace atmosphere of the selected sinter 267
plant. For total PAH, concentrations of the gas-phase PAHs (8.33-30.1 μg Nm-3, accounting 268
for 98.3%-99.5% total PAHs) were consistently higher than that of particle-phase 269
(0.042-0.365 μg Nm-3, accounting for 0.5%-1.7% total PAHs) for any given studied 270
workplaces (p<0.05). The above results can be explained by total PAHs were dominated by 271
LMW-PAHs (Table 3). For total BaPeq, concentrations of the gas-phase (0.037-0.121 μg
272
Nm-3) were also higher than that of particle-phase (0.003-0.039 μg Nm-3) for any given 273
studied workplaces (p<0.05). However, particle-phase PAHs had more contribution to total 274
BaPeq (8.1-24.1%) than to total PAHs (0.5%-1.7%). The above results can be explained by
275
total PAHs were dominated by LMW-PAHs which are known with low TEFs (Table 3). 276
Finally, it should be noted that the concentrations of both gas- and particle-phase 277
PAHs found in the outdoor environment (site #5) were consistently lower than that of the 278
sintering zone (i.e., Site #1-Site #3) (p<0.05) (Table 4). Particularly, the contributions of 279
gas- and particle-phase PAHs to both total PAHs and total BaPeq for samples collected from
280
the outdoor environment were quite different from that of sintering zone (p<0.05) (Table 4). 281
The above results further confirm that PAHs found in the workplace environments were 282
mainly contributed by the process fugitives rather than the outdoor environment. 283
3.4. Health-risk assessment for sintering workers exposed to PAHs 284
In this study, worker’s time-weighted average exposure was estimated based on the 285
following equation: 286
Cave=(Ci × Ti)/ΣTi
287
Where, Cave was the worker’s time-weighted average exposure to total PAHs (denoted as
288
total PAHsave) and total BaPeq (denoted as total BaPeqave); Ci was the worker’s exposure
289
concentration to total PAHs at the ith site (i.e., total PAHsi, see Table 3) and to total BaPeq
290
at the ith site (i.e., total BaPeqi, see Table 2); Ti was the time of the given worker spent at
291
the ith site (see Table 1); and ΣTi was the time for the given worker spent at all involved
292
work sites. 293
Table 5 shows total PAHsave and total BaPeqave, and their corresponding gas-phase
294
and particle-phase concentrations. In addition, the estimated lung cancer risks for the four 295
selected exposure groups based on their total BaPeqave and the corresponding gas-phase and
296
particle-phase concentrations were also presented in Table 5. For total PAHsave, its
297
corresponding gas-phase concentration (=82.3121 ng m-3) was consistently higher than 298
that of particle phase (=0.68523.3 ng m-3) (p<0.05). Particularly, all selected exposure 299
groups were found with total PAHsave (=83.0122 ng m-3) significantly lower than the
300
current permissible exposure limit regulated in Taiwan for PAHs (=200,000 ng/m3) 301
(p<0.05). The above results suggest that PAH exposures to sintering workers might not be 302
particularly significant. In this study, the unit risk suggested by Pott in 1985 (=7×10-5 303
(BaPeq ng m-3) -1) was used to assess workers’ any excess of risk for lung cancer associated 304
with a 25-yr occupational exposure [17]. We found that the total BaPave fell to the range of
305
0.4540.705 ng m-3. The corresponding gas-phase concentration (=0.4500.614 ng m-3) 306
was significantly higher than that of particle-phase (=0.0040.137 ng m-3) (p<0.05) 307
suggesting that the former had a more contribution on worker’s lung cancer risk. However, 308
by taking both gas- and particle-phase together (i.e., total BaPave), the resultant lung cancer
309
risks (=3.18×10-54.98×10-5) were consistently lower than the significant risk level (=10-3) 310
which was defined by the US Supreme Court [30]. The above results further confirm that 311
PAH exposures to sintering workers might be acceptable at this stage. 312
313
4. Conclusions 314
The present paper shows that both TSP and total PAH concentrations of the three 315
selected sintering process areas were higher than that of the control room. The above results 316
could be explained by the filtration efficiency of the air conditioning device installed inside 317
the control room. PAH homologue distributions of the three selected sintering process areas 318
were significantly different from that of the outdoor environment suggesting that PAHs 319
found in the sintering workplace atmospheres were mainly contributed by process fugitives. 320
Total PAH exposure levels in the selected areas of the sintering plant were lower than the 321
current permissible exposure limits, thus suggesting that sintering workers are usually 322
exposed to quite low PAH concentrations. Consistently, our risk estimate for the lung 323
cancer risks associated with the above PAH exposures gave lower values as compared to 324
the significant risk level defined by US Supreme Court. 325
326
Acknowledgments: This research was supported in part by the Institute of Occupational 327
Safety and Health (IOSH) of the Council of Labor Affairs in Taiwan. Mr. H.C. Hou and 328
Miss UnSam Ha, Department of Environmental Engineering, National Cheng Kung 329
University, are appreciated for assisting in the laboratory work. 330
331
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Table Captions 419
Table 1 Time/activity patterns for the four selected groups of workers of the Group A: 420
raw material charging workers, Group B: sintering grate workers, Group C: 421
shredding workers, and Group D: sintering process engineers and supervisors 422
at the four selected workplaces inside the sinter plant of the Site #1: raw 423
materials inlet, Site #2: sintering grate, Site #3: Rough roll shredder, and Site 424
#4: control room 425
Table 2 Mean TSP concentrations (SD) of the four selected workplaces inside the 426
sinter plant of the Site #1: raw materials inlet, Site #2: sintering grate, Site 427
#3: Rough roll shredder, and Site #4: control room, and its outdoor 428
environment (Site #5) 429
Table 3 Mean PAH concentrations (SD) of the four selected workplace atmospheres 430
of the sinter plant of the Site #1: raw materials inlet, Site #2: sintering grate, 431
Site #3: Rough roll shredder, and Site #4: control room, and its outdoor 432
environment (Site #5) 433
Table 4 Mean PAH concentrations (SD) of the four selected workplace atmospheres 434
of the sinter plant of the Site #1: raw materials inlet, Site #2: sintering grate, 435
Site #3: Rough roll shredder, and Site #4: control room, and its outdoor 436
environment (Site #5) 437
Table 5 Time-weighted average exposure levels (SD) of total PAHsave and total
438
BaPeqave and their corresponding particle-phase and gas-phase exposure
439
levels (SD), and the resultant lung cancer risks (SD) for the four selected 440
exposure groups of the Group A: raw material charging workers, Group B: 441
sintering grate workers, Group C: shredding workers, and Group D: sintering 442
process engineers and supervisors 443
444
Figure Caption 445
Figure 1 Sampling sites in the selected sintering plant 446
