Occupational health risk assessment based on actual dust exposure in a tunnel construction adopting roadheader in Chongqing, China

Building and Environment 165 (2019) 106415

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Occupational health risk assessment based on actual dust exposure in a tunnel construction adopting roadheader in Chongqing, China

T

Xiaofeng Chena,b, Chun Guoa,b,∗, Junxiu Songa,b, Xin Wanga,b, Jianghao Chenga,b a b

School of Civil Engineering, Southwest Jiaotong University, 111 Erhuan Rd, Chengdu, 610031, Sichuan, China Key Laboratory of Transportation Tunnel Engineering, Ministry of Education, Southwest Jiaotong University, 111 Erhuan Rd, Chengdu, 610031, Sichuan, China

A R T I C LE I N FO

A B S T R A C T

Keywords: Occupational health risk assessment Tunnel construction Dust pollution Dust mask Isolation effect

Tunnel construction, especially those excavated by roadheader, will produce great dust pollution, which always result in serious health risks to workers. In order to reveal the health risk characteristics of tunnel construction dust and improve the workers’ occupational health level, combining the tunnel construction characteristics, this paper established a health risk assessment system based on field measurement. The assessment system consisted of exposure assessment and risk quantification adopting disability-adjusted life year(DALY). Then, the willingness to pay(WTP) was employed to monetize health risk and endow health risk with economic significance, that is, the cost to reduce risk. In this paper, the isolation effect of dust masks in tunnel construction was taken into account for the first time, and the dust exposure concentration of workers was corrected by a unique formula according to the inward leakage(IL) and filtration efficiency(FE). The results showed that the isolation of masks obviously reduced the health risk, in which health risk was drastically reduced by 82% under ideal isolation effect and by 26% under actual isolation effect. In each procedure, the health risk of tunneling was the greatest, followed by slag-out, and the smallest was lining. In addition, although the dust pollution of lining was light, due to long working hours(9.0h) and high intake rate, also leading to serious health risk (total DALY = 0.18a, total WTP = $14,606) without isolation effect. This paper refined the health risk endpoint, improved the accuracy of assessment, and provided a reference for construction workers to strengthen dust prevention.

1. Introduction Tunnel construction has always been a research hotspot in the field of civil engineering, especially involving advanced construction technology [1–3], construction ventilation [4–6], disaster prevention [7–9], as well as energy-saving and emission reduction [10–12] and so on. Even with more and more advanced construction technology and more and more perfect construction administration, workers in the construction industry are still suffering from dust pollution containing massive hazardous materials such as silica. Previous studies [13–16] have indicated that the hazards of dust on human health were mainly reflected in respiratory diseases such as pneumoconiosis, chronic obstructive pulmonary disease(COPD), asthma and so on. According to the report [17], 226 out of the 2851 workers in the Engineering Bureau of the former China Ministry of Railways Engineering Corporation were pneumoconiosis patients, and the prevalence rate was as high as 7.9%. In the tunnel construction project, due to the closed construction environment and poor ventilation system, workers are more likely to be exposed to more concentrated dust and are more susceptible to

∗

respiratory diseases [18,19]. In order to deal with the tunnel construction dust, while many scholars have carried out a series of studies, mainly focusing on dust diffusion law [20–22], dust-induced diseases [23–25]and dust-control measures [26–28], few paid attention to health risk assessment. Especially in the tunnel construction adopting roadheader, dust is one of the biggest threats to workers' health [29,30]. In order to clarify the risk of dust on human health, a risk assessment must be carried out. The risk assessment is a process of taking a certain method to evaluate the probability and severity of some risks in a certain event, so as to take appropriate measures to reduce the probability of risk. As far as the assessment method is concerned, there are qualitative, semi-quantitative and quantitative analysis method. Specifically, there are Logistic Regression Model [31], Fuzzy Analytic Hierarchy Process (FAHP) [32], Delphi method [33], International Mining and Metals Council (IMMC) Health Risk Assessment Act [34], Operational Conditions Risk Assessment (LEC) Act [35], Occupational Hazard Risk Index Assessment [36]and Occupational Health Risk Assessment Model of US Environmental Protection Agency (USEPA) [37].

Corresponding author. School of Civil Engineering, Southwest Jiaotong University, 111 Erhuan Rd, Chengdu, 610031, Sichuan, China. E-mail address: [email protected] (C. Guo).

https://doi.org/10.1016/j.buildenv.2019.106415 Received 4 May 2019; Received in revised form 23 August 2019; Accepted 11 September 2019 Available online 12 September 2019 0360-1323/ © 2019 Elsevier Ltd. All rights reserved.

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adopted to construct. During the construction, due to the hard surrounding rock, the boom-type roadheader produced serious dust pollution when cutting the rock. In this paper, a construction zone of the project was taken as an example to assess the health risk during the construction. And the tunnel is equipped with necessary mechanical ventilation and dust-removal system. All workers adopted three shifts, who are all male.

Among them, the most extensively used and most mature method is the Occupational Health Risk Assessment Model created by USEPA [38–40], which is mainly carried out in four steps: hazard identification, dose-response assessment, exposure assessment and risk characterization. Combined with modern construction technology and national physique, some researchers [41–43]proposed an assessment method consisting of exposure assessment and risk quantification based on the theory of USEPA, which could quantitatively evaluate the risk of dust exposure. Although the above assessment methods are widely used, they almost neglect one critical point which is the isolation effect of personal dust masks. As we all know, the dust enters the worker's body mainly through inhalation. As construction workers' self-protection awareness is gradually increasing, dust masks will be worn in the dust pollution workplace, which results in the actual exposure areas are concentrated near the nose and mouth. Therefore, when conducting the health risk assessment, the actual dust exposure concentration of the worker's nose and mouth should be considered rather than the ambient dust concentration. The focus of this paper is to clarify the health risk when workers are exposed to great dust pollution in a tunnel construction adopting the roadheader. In this paper, the isolation effect of the dust mask will be taken into account for the first time. Meanwhile, some appropriate corrections to the current assessment system were conducted based on the actual dust concentration, with a view to providing help and suggestions for individuals and policymakers.

2.2. Sampling protocol Tunnel construction usually involves multiple procedures (Fig. 2), and the dust concentration that workers contact in each procedure varies greatly. Therefore, it is necessary to measure the dust concentration of each procedure. According to the actual situation, in order to avoid impacting the construction, multi-point sampling for each procedure was taken. In the same procedure, three different locations that are as close as possible to the workers were selected for measurement, which was present in Fig. 3. The tunneling and arching were all in the tunneling face, so the measuring points of the two procedures were arranged in the same position. At the height of breathing zone (1.2m–1.5 m), the measurement was conducted according to the specifications [44]. The dust concentration (total dust) was measured three times at each location, with 5 min of sampling time each time, and then the average value was taken as the dust concentration in the procedure. The instrument adopted in this paper was a direct-reading dust detector(Fig. 4). With convenience, rapidity and accuracy, it was employed widely in many fields, such as tunnel engineering [45,46], architectural engineering [43] and coal engineering [47]. The partial field measurement was shown in Fig. 5.

2. Materials and methodology 2.1. Sampling sites The project named Chongqing Zengjiayan Jialing River Bridge Tunnel (Fig. 1)is located in the downtown of Chongqing, which is worn under a variety of existing structures (office buildings, residential buildings, schools, subway lines, etc.) with a shallow buried depth. In order to control surface settlement strictly, boom-type roadheader was

2.3. Actual dust exposure Tunnel construction dust affects workers' health through mouth and nose. However, almost all tunnel workers would wear personal protective equipment (such as dust mask) during construction. Therefore,

Fig. 1. Location of tunnel construction. 2

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Fig. 2. Typical procedures of a tunnel construction.

Fig. 3. Overview of the construction site and layout of measuring points.

the ambient dust concentration should be replaced by the actual value that nose and mouth contact. The national regulations on the isolation performance of the dust mask mainly include two factors: filtration efficiency (FE) and inward leakage (IL) [48]. The filtration efficiency refers to the percentage of particulate matter filtered by the filtration element under the specified detection conditions, so the filtration efficiency of the dust mask is defined as Eq. (1).

FE =

C0 − C1 × 100% C0

represents the dust concentration entering the mask only through the filtration element (mg/m3). C0 represents the ambient dust concentration (mg/m3). The definition of the inward leakage of the dust mask is shown in Eq. (2).

IL =

1.7 × (Cb − Ca) × 100% C0

(2)

Where Cb represents the dust concentration leaking into mask except filtering (mg/m3). Ca represents the background dust concentration in dust mask(mg/m3).

(1)

Where FE represents the filtration efficiency of the dust mask. C1 3

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Fig. 4. Direct-reading dust detector.

Combining Eq. (1) and Eq. (2), the actual dust concentration can be determined, as shown in Eq. (3).

CA =

IL × C0 + 2 × Ca + C0 × (1 − FE ) 1.7

(3)

According to China's relevant national standards, the inward leakage of replaceable half-masks should be less than 5%. And the ideal filtration efficiency of dust masks is divided into three types, which are KN90(≥90.0%), KN95(≥95.0%) and KN100(≥99.97%) separately. According to the existing research [49], the actual qualified rate of dust masks in China was 40.58%. Due to the poor quality and inappropriate usage, the actual filtration efficiency was 46.01%, while the actual inward leakage was 30.8%. 2.4. Health risk assessment In this paper, a health risk assessment model in the field of public environmental health was employed to quantitatively assess the occupational exposure of tunnel construction workers. The model framework is shown in Fig. 6, in which the health risk quantification consists of disability-adjusted life year (DALY) and monetized health loss [50,51].

Fig. 6. Health risk assessment framework of construction dust.

2.4.1. Dust exposure assessment In the dust exposure assessment, the actual dust exposure concentrations need to be converted into the average daily dose (ADD) of

Fig. 5. Field measurement situations in partial procedures: (a).tunneling, (b). Slag-out. 4

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the workers, which can be derived from Eq. (4).

ADD =

Table 2 Risk factors and related parameters.

CA × IR × ED × EF × ET BW × AT

(4)

Where ADD represents the average daily dose of the dust that workers contact (mg/(kg·d)). IR is the inhalation rate (m3/h). ED represents workers' continuous exposure duration (a), equaling to the duration of each construction procedure. EF represents workers' continuous exposure frequency (d/a), equaling to the days of each year. ET represents workers' average daily exposure time (h/d). BW represents the workers' average weight (kg). AT represents workers' average exposure time (d), equaling to the duration of each construction phase. CA represents workers' actual dust exposure concentration (mg/m3). In this paper, the IR of construction worker should be short-term inhalation rate and matched with labor intensity. According to relevant research [42]and on-site investigation, the lining belongs to heavy physical labor. The slag-out adopts large-scale construction machinery without too much labor intensity, so it belongs to light physical labor, and the other jobs belong to medium physical labor. Combined with the Chinese Population Exposure Parameter Handbook (Adult Volume) [52], the worker's IR can be determined. The worker's BW needed to be determined according to the on-site investigation. In summary, the time-behavior pattern and exposure characteristics of workers were shown in Table 1.

ADD × 10−6 RfD

Risk factor Q

Effect factor W

Duration of risk L(a)

Death COPD Pneumoconiosis Angiocardiopathy CVD ARTI

0.10 0.11 0.28 0.11 0.16 0.24

1 0.15 0.24 0.24 0.20 0.08

L0 10 L0 L0-5 L0-5 0.038

L0 is the standard average expected residual life of the worker, which is shown in Table 3. And pneumoconiosis is generally difficult to cure completely, so its duration is L0.

and death. The years of health loss and premature death life loss caused by construction dust can be quantified by effect analysis and damage analysis. The quantified results are called disability-adjusted life years (DALY), which can be determined according to Eq. (6).

DALY = n ×

∑ R × Qi × Wi × Li × P

(6)

Where Qi represents the risk factor of disease i, Wi represents the effect factor of disease i, Li represents the damage factor of disease i (a), P represents the number of people affected by the damage, n represents exposure days, equal to the construction period(d). According to relevant researches [56–61], the risk factors and other parameters are shown in Table 2. Through investigation, the average life expectancy(ALE) of men is 76.7 years [62].

2.4.2. Health risk characterization In current health risk assessment systems, harmful contaminants are divided into two categories: threshold compounds (typically non-carcinogens) and threshold-free compounds (typically carcinogens) [53]. Construction dust in this paper belongs to the threshold harmful contaminant. According to previous studies [37], the risk index R determined by Eq. (5) can be employed to characterize the health risk.

R=

Health risk

2.4.4. Health risk monetization In order to give health risk economic significance, this paper intended to monetize DALY of each health risk, that was, adopt social willingness to pay (WTP) to characterize the economic cost that was willing to pay for reducing the risk of disability or death. Monetizing of health risk was determined by Eq. (7) and Eq. (8).

(5)

(7)

WTP = DALY × VSLY

Where R represents the risk index that dust damages health and RfD represents the reference dose of dust(mg/(kg·d)). At present, there is no direct value for the RfD of dust. According to the related studies [41,43], a kind of related substance whose RfD was known can be According to previous studies [37], the risk index R determined by Eq. (5) can be employed to characterize the health risk. to calculate indirectly the RfD of dust, through comparative iteration. According to previous studies [54], the comparative substance may be dibutyl phthalate (DBP), and the RfD of dust were determined to be 0.4 mg/kg·d (silica dust) and 1.6 mg/kg·d (cement dust) [55].

VSLY =

VSL [1 − (1 + r )−t ]/ r

(8)

Where WTP represents the economic cost of reducing health risk(Dollar).VSLY represents the unit value of monetizing health risk(Dollar/a). t represents the life expectancy, equaling to L0. r represents the utility discount rate, which is 4% based on the relevant literature [63]. The determination of the economic cost of DALY was mostly based on the value of a statistical life (VSL) of American [64], that was $7 million. By calculating the US dollar inflation rate and comparing the current purchasing power parity (calculated by GDP per capita) between China and the United States, the average VSL of residents in the construction site can be calculated. In 2018, the GDP per capita of China and the United States were $9746 [65]and $62,000 [66], respectively. The total inflation rate in the United States from 2000 to 2018 was about 48.83% [67]. In 2018, the per capita GDP of Chongqing in China was $9963 [68], so the per capita VSL in this paper was $1.671 million.

2.4.3. Health risk quantification At present, there were two kinds of health risks about construction dust, one contained death, but not pneumoconiosis [41,43,55–57]; the other contained pneumoconiosis [58,59], but not death. Combining the above researches, the health risks in this paper were pneumoconiosis, chronic obstructive pulmonary disease(COPD), cerebrovascular disease (CVD), angiocardiopathy and acute respiratory tract infection(ARTI), Table 1 Time-behavior pattern and exposure characteristics of workers. Procedure

Tunneling Slag-out Arching Shotcrete Lining

Number of workers

6 6 12 6 20

IR(m3/h)

ET(h/d)

BW (kg)

Working

Rest

Working

Rest

1.506 0.564 1.506 1.506 2.262

0.45 0.45 0.45 0.45 0.45

8.5 7.0 8.5 8.5 9.0

1.0 2.0 1.0 1.0 1.0

Note: Data of BW and Year are expressed as mean ± standard deviation. 5

66.5 67.5 69.3 66.0 68.5

± ± ± ± ±

Year (a)

4.3 4.0 3.9 4.2 4.3

40.2 34.7 40.6 38.7 32.7

± ± ± ± ±

3.5 5.2 5.4 5.3 3.7

EF (d/a)

ED (a)

AT (d)

331

2

730

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3.2. Health risk assessment

Table 3 The average expected residual life of the worker. Procedure

Average Year (a)

Average life expectancy (a)

Expected residual life (a)

Tunneling Slag-out Arching Shotcrete Lining

40.2 34.7 40.6 38.7 32.7

76.7

36.5 42.5 36.1 38.0 44.0

Substituting various parameters into Eq. (1)-Eq. (8), the quantitative assessment of the health risk was obtained, in which the workers wore the masks with three filtering states including ideal isolation effect, actual isolation effect and non-isolation effect (without mask). 3.2.1. Analysis with no isolation effect Without wearing any dust masks, the results of the quantitative assessment of the health risk are shown in Table 6. In Table 6, the total health risk of workers reached 58.13 × 10−6, exceeding the limit recommended by USEPA, which was 10−6. The health risks of all workers in working state exceed the limit. However, in the rest state, only the health risks of the tunneling and slag-out exceeded the limit, reaching 1.32 × 10−6 and 2.29 × 10−6 separately, which resulted from too long exposure time and great dust concentration. As shown in Table 6, during the tunnel construction procedures, dust would cause serious health risks to workers without any protective measures, in which the total DALY was 2.14a and the economic cost was $184,124. Among them, the health risk of tunneling was the largest (1.25a, $109,568), followed by slag-out, which was basically consistent with the previous research [42]. In this paper, the tunnel was excavated by a roadheader, so the tunneling workers were near the tunneling face, contacting the dust at first. In addition, the dust-removal measures didn't work well, so the health risk of the tunneling worker was the greatest. It should be noted that the dust concentration of slag-out workers was quite large (75.71 mg/m3), second only to the tunneling workers (85.75 mg/m3), but the health risk value of the slag-out was about 67% lower than the tunneling. Generally speaking, the slag-out was carried out after the roadheader produced a certain amount of slag, so the effective working time is relatively short (7.0h), and the workers always rest during the other time(2.0h), with low IR. Therefore, the health risk of the slag-out was obviously less than tunneling.

3. Results and discussion 3.1. Sampling results and analysis The ambient dust concentration and other information of the workers in this project were shown in Table 4. The dust concentrations recorded in different procedures ranged between 0.16 and 85.75 mg/m3, in which the tunneling suffered from the worst dust pollution and slag-out was in second. In addition to the dust concentration outside, silica dust and cement dust of other procedures exceeded seriously the limits stipulated in Highway Tunnel Construction Technical Specifications [69], which were 1 mg/m3 (silica dust) and 4 mg/m3 (cement dust), respectively. Tunneling procedure was the main dust source, which resulted that the dust concentration (85.75 mg/m3) was 85 times as high as the limit. Slag-out may contribute to producing new dust and rising deposited dust, which aggravated the dust pollution. And the average concentration of cement dust was also far greater (about 700% exceeded) than the limit, owing to the rushing between cement and wall. In order to verify the rationality of sampling the construction dust in this paper, the sampling results and sampling position were compared with other researches, and the comparison was shown in Table 5. Drilling and Blasting Method is commonly used in tunnel construction in China, but tunneling machine method is seldom used. While roadheader is mostly used in rock roadway construction in coal mine engineering, so the researches used for comparison involves traffic tunnels and mine rock roadways. Through comparison, it is found that the ambient dust concentration and sampling position of most procedures are within the reasonable range of the existing researches except the slag-out. Different from the existing researches, the sampling position of the slag-out in this paper was near the temporary slag filed, and the tunneling did not stop during the slag-out. In addition, the transportation machinery would stir up more dust when dumping rock slag, so the ambient dust concentration of slag-out in this paper is relatively large. Because the tunnel was located in downtown with the strict environmental protection, the construction dust cannot be directly discharged to the air and must be handled inside. However, according to the on-site investigation, the ventilation and dust-removal measures in the tunnel did not work well, which eventually resulted in serious exceedance.

3.2.2. Analysis with isolation effect Considering the isolation effect of dust masks, the health risk assessment of workers were shown in Fig. 7. As shown in Fig. 7, among the various procedures of tunnel construction, the health risk of tunneling in the three cases was the greatest, followed by the slag-out. In Fig. 7, unlike the change of the Per Capita DALY in (a), the total DALY of lining in (b) was greater than arching and shotcrete. There are three main reasons for this: firstly, the number of lining worker is the largest reaching 20 people, resulting in a larger total health risk; secondly, although the dust exposure concentration of lining workers is low (2.01 mg/m3), their effective working time is the longest (9.0h); finally, because of the climbing up and down for assembling reinforcement, lining belongs to heavy physical labor [42,73], and their IR is faster. If the masks were qualified and were worn properly, the health risk of tunnel workers would be reduced by 82%(Fig. 7). Due to the uneven quality and the inappropriate usage of dust masks [74,75], although the health risk of workers dropped obviously(26%), the final health risk was still very serious. Especially the workers from tunneling, slag-out and lining must strengthen personal protection.

Table 4 Dust exposure overview of workers in different procedures. Procedure

Dust type

Position

Mask type

Dust concentration(mg/m3)

Tunneling Slag-out Arching Shotcrete Lining

Silica dust Silica dust Silica dust Cement dust Silica dust

Next to the driver Temporary slag filed Initial support trolley Initial support trolley Lining trolley

KN95 KN90 KN90 KN90 KN90

85.75 ± 6.02 75.71 ± 4.99 4.51 ± 0.55 32.74 ± 2.47 2.01 ± 0.28

Note: Data of dust concentration is expressed as mean ± standard deviation. 6

full-mask half-mask half-mask half-mask half-mask

85.75 ± 6.02 Next to the driver (5–7 m from tunneling face) 75.71 ± 4.99 Temporary slag filed 4.51 ± 0.55 Initial support trolley (5–7 m from tunneling face) 32.74 ± 2.47 Initial support trolley (5–7 m from tunneling face) 2.01 ± 0.28 Lining trolley

Concentration Position Concentration Position Concentration Position

Concentration Position

Concentration Position

Tunneling

Shotcrete

Lining

Note: The unit of concentration is mg/m3.

Arching

Slag-out

Sampling results of this paper

Concentration and position

Procedure

Table 5 Comparison between the sampling of this paper and other researches.

/ /

75 Next to the tunneling face

About 30-88 Next to the tunneling face / / / /

Youzhushan Tunnel [70]

/ /

About 36-105 5–10 m from tunneling face

About 12-32 5–10 m from tunneling face About 16-30 5–10 m from tunneling face About 4-12 5–10 m from tunneling face

Xinzhuang Tunnel [46]

About 1.01 Lining trolley

About 44.59 Tunneling face

About 0.9–30.15 Tunneling face About 0.5 / About 2.28 Tunneling face

Tianmushan Tunnel [71]

/ /

/ /

167.6 Next to the driver / / / /

Zhuxianzhu-ang Mine [72]

12.64 Lining point

17.38 Shotcrete operating point

19.38 Next to the driver 16.54 Next to rock loader / /

A Mine in Shanxi Province [58]

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Table 6 Quantitative assessment of the health risk (without dust masks).

Slog-out

Arching

Shotcrete

Lining

Total

7 Procedure Worker's status ADD [mg/ (kg·d)] RfD [mg/ (kg·d)] R (10−6) DALY (a) WTP (Dollar)

Tunneling working rest working rest working rest working rest working rest 14.97 0.53 4.02 0.92 0.76 0.03 5.76 0.20 0.54 0.01 0.40 0.40 0.40 0.40 0.40 0.40 1.60 1.60 0.40 0.40 37.42 1.32 10.04 2.29 1.89 0.07 3.60 0.13 1.35 0.03 58.13 1.25 109568

0.46 38176

0.12 10784

0.12 10991

0.18 14606

2.14 184124

Fig. 7. DALY of different construction procedures:(a). Per Capita DALY, (b). Total DALY.

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Table 7 Economic cost(USD) of reducing health risk at different isolation effect. Health risk

Death Pneumoconiosis CVD Angiocardiopathy COPD ARTI Total Per Capita

No-isolation effect

Actual isolation effect

Economic cost

Percentage(%)

Economic cost

Percentage(%)

Economic cost

Percentage(%)

82829 55661 23036 19004 3578 16 184124 3682

44.99 30.23 12.51 10.32 1.94 0.01 100 -

61044 41021 16982 14010 2632 12 135701 2714

44.98 30.23 12.52 10.32 1.94 0.01 100 -

9952 6688 2777 2291 420 2 22130 442

44.97 30.22 12.55 10.35 1.90 0.01 100 -

the relevant literature, which may be deviated from the performance of the mask on site. Therefore, the performance of the dust mask worn by the construction workers should be tested on site.

3.3. Economic cost In order to reduce those health risk result from tunnel construction dust, people always pay much money, which must lead to great economic cost. The monetization of health risks was shown in Table 7. As shown in Table 7, the greatest health threat faced by tunnel workers during tunnel construction was death (approximately 45%), followed by pneumoconiosis(approximately 30%) and CVD(approximately 13%). Because pneumoconiosis was difficult to cure, its economic cost was very high, second only to death. But the symptom of ARTI was always not serious which was easy to healing, so its economic cost was the minimum. Although two-year tunnel construction could result in an economic cost up to $184,124 for workers(Table 7), proper wearing of qualified dust masks may obviously reduce the cost up to $161,994 and effectively reduce the workers’ burden. Through calculation, the per capita daily WTP of health risk caused by construction dust shown in Table 8, which was from architectural engineering and tunnel engineering. Through comparison, it was found that the per capita daily health risk caused by tunnel construction was more than that of architectural engineering, in which the maximum and minimum difference were $5.19(under no isolation) and $0.26(under ideal isolation) separately. Usually, the dust pollution of architectural engineering is slight, meanwhile the construction filed is open and easy to ventilate, so the health risk is very small. Tunnel engineering is much different from architectural engineering, only the effective dust-removal system and strong self-protection can effectively reduce health risk and economic cost.

3.5. Dust control measures In order to reduce the health risks caused by dust during tunnel construction, effective measures should be taken to control dust. At present, the common dust control measures are mainly divided into three styles: suppress dust by foam or water mist [76,77], isolate dust by air curtain [78,79] and remove dust by dust-removal system [80]. Because the above measures have inevitable defects, in the case of high dust concentration, a comprehensive dust control measure(Fig. 8) including above measures are required. Firstly, in the process of tunneling, the cutting area is covered by water mist or foam, and most of the dust is suppressed at the source. Secondly, through the rotating air curtain formed by the wall-attached duct at the end of press-in duct, the dust that has not been suppressed is isolated near the tunneling face to prevent it from spreading. Finally, when the dust is successfully isolated, the dust-removal system can extract out and settle the dust. 4. Conclusions This paper established a health risk assessment system based on the actual dust exposure concentration of tunnel workers, consisting of exposure assessment and risk quantification, and for the first time considering the filtering effect of dust masks. Through the field application, this paper theoretically indicated that the actual exposure dose of dust should be taken when assessing the health risk. The main conclusions are listed below:

3.4. Limitations Firstly, in the assessment system, there was no accurate official value when it comes to the RfD of dust, but it was replaced by dibutyl phthalate (DBP). Although many researchers have accepted it, whether it is reasonable or not is still debatable. And the determination of health risk factors was based on the comparison of data from existing researches, which did not include all health risks of this paper, so special research should be carried out. Secondly, the actual isolation effect of dust mask was derived from

(1) In the tunnel construction adopting a roadheader, the construction workers suffer great health risk due to serious dust pollution. And there are obvious differences between the various procedures, of which the tunneling workers suffer from the greatest health risk, followed by the slag-out workers. (2) In the tunnel construction adopting a roadheader, although the lining workers exposure to light dust pollution, due to their long working time (9.0h) and high IR (2.262 m3/h), the lining workers' health risk is also relatively serious. It needs to focus on strengthening personal dust prevention of lining workers except for tunneling and slog-out. (3) Wearing dust masks in construction can obviously reduce health risk, up to 82% (ideal isolation effect), and the worst is 26% (actual isolation effect). Improving the quality of dust masks and standardizing the usage would greatly improve the health level. (4) Based on the performance parameters of the dust mask, the formula for calculating the actual exposure concentration of construction ILC workers is put forward: CA = 1.70 + 2Ca + C0 (1 − FE ) .

Table 8 Comparison of the economic cost of health risk among different engineering. Engineering type

1 # Architectural engineering [41] 2 # Architectural engineering [55] Tunnel engineering

Ideal isolation effect

Dust concentration (mg/m3)

Per Capita daily cost (USD)

Isolation effect of mask

min

max

0.47

9.65

0.37

No

0.30

9.72

0.41

No

2.01

85.75

5.56 4.10 0.67

No Actual Ideal

8

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Fig. 8. Layout of comprehensive dust control measures.

Acknowledgments [14]

The work was supported by The National Key Research and Development Program of China (2016YFB1200401), Regional Public Management Information Research Center Funding Project (QGXH1808) and Sichuan Education and Research Funding Project (2018495).

[15]

References

[16]

[1] W. Qi, L. Ying-Cheng, J. Bei, L. Shu-Cai, H. Man-Chao, S. Hui-Bin, Q. Qian, L. Wei, Study on key technology of tunnel fabricated arch and its mechanical mechanism in the mechanized construction, Tunn. Undergr. Space Technol. 83 (2019) 187–194 https://doi.org/10.1016/j.tust.2018.10.002. [2] X. Fei, L. Shu-Cai, Z. Qian-Qing, L. Li-Ping, S. Shao-Shuai, Z. Qian, A new type support structure introduction and its contrast study with traditional support structure used in tunnel construction, Tunn. Undergr. Space Technol. 63 (2017) 171–182 https://doi.org/10.1016/j.tust.2016.11.012. [3] C.T. Carlos, E. Maxwell, The support characteristic curve for blocked steel sets in the convergence-confinement method of tunnel support design, Tunn. Undergr. Space Technol. 69 (2017) 233–244 https://doi.org/10.1016/j.tust.2017.04.003. [4] G. Chun, X. Jian-Feng, Y. Lu, G. Xiong, Z. Yun-Long, W. Ming-Nian, Energy-saving network ventilation technology of extra-long tunnel in climate separation zone, Appl. Sci. 7 (2017) 454 https://doi.org/10.3390/app7050454. [5] G. Chun, W. Ming-Nian, Y. Lu, S. Zhi-Tao, Z. Yun-Long, X. Jian-Feng, A Review of energy consumption and saving in extra-long tunnel operation ventilation in China, Renew. Sustain. Energy Rev. 53 (2016) 1558–1569 https://doi.org/10.1016/j.rser. 2015.09.094. [6] G. Chun, X. Jian-Feng, W. Ming-Nian, Y. Tao, Y. Lu, S. Zhi-Tao, Study on oxygen supply standard for physical health of construction personnel of high-altitude tunnels, Int. J. Environ. Res. Public Health 13 (1) (2016) 64 https://doi.org/10. 3390/ijerph13010064. [7] Z. Guo-Hua, J. Yu-Yong, C. Li-Biao, W. Hao, L. Shu-Cai, An analytical model for assessing the collapse risk during mountain tunnel construction, Can. Geotech. J. 53 (2) (2015) 326–342 https://doi.org/10.1139/cgj-2015-0064. [8] Y. Yong-Zheng, L. Ying-Zhen, L. Anders, I. Haukur, C. Xu-Dong, Study of tunnel fires during construction using a model scale tunnel, Tunn. Undergr. Space Technol. 89 (2019) 50–67 https://doi.org/10.1016/j.tust.2019.03.017. [9] L. Shu-Cai, T. Hao, X. Yi-Guo, S. Mao-Xin, Q. Dao-Hong, L. Li-Ping, L. Zhi-Peng, Study on major construction disasters and controlling technology at the qingdao kiaochow bay subsea tunnel, J. Coast. Res. 73 (2015) 403–409 https://doi.org/10. 2112/si73-071.1. [10] X. Jian-Feng, G. Chun, Y. Li, Factors influencing and methods of predicting greenhouse gas emissions from highway tunnel construction in southwestern China, J. Clean. Prod. 229 (2019) 337–349 https://doi.org/10.1016/j.jclepro.2019.04. 260. [11] G. Chun, X. Jian-Feng, Y. Lu, G. Xiong, L. Ji-Xuan, Z. Xin, Z. Zhen-Hua, C. XiaoFeng, Y. Kun, W. Ming-Nian, Life cycle evaluation of greenhouse gas emissions of a highway tunnel: a case study in China, J. Clean. Prod. 211 (2019) 972–980 https:// doi.org/10.1016/j.jclepro.2018.11.249. [12] X. Jian-Feng, G. Chun, C. Xiao-Feng, Z. Zhen-Hua, Y. Lu, W. Ming-Nian, Y. Kun, Emission transition of greenhouse gases with the surrounding rock weakened–A case study of tunnel construction, J. Clean. Prod. 209 (2019) 169–179 https://doi. org/10.1016/j.jclepro.2018.10.224. [13] A. Omidianidost, M. Ghasemkhani, M.R. Azari, F. Golbabaei, Assessment of

[17]

[18]

[19]

[20]

[21]

[22]

[23]

[24]

[25]

[26]

[27]

[28]

[29]

[30]

9

occupational exposure to dust and crystalline silica in foundries, Tanaffos 14 (2015) 208. A. Maciejewska, Occupational exposure assessment for crystalline silica dust: approach in Poland and worldwide, Int. J. Occup. Med. Environ. Health 21 (2008) 1–23 https://doi.org/10.2478/v10001-008-0010-3. N. Zheng, L. Jing-Shuang, W. Qi-Chao, L. Zhong-Zhu, Health risk assessment of heavy metal exposure to street dust in the zinc smelting district, Northeast of China, Sci. Total Environ. 408 (4) (2010) 726–733 https://doi.org/10.1016/j.scitotenv. 2009.10.075. A. Tarafdar, A. Sinha, Health risk assessment and source study of PAHs from roadside soil dust of a heavy mining area in India, Arch. Environ. Occup. Health 2 (2018) 1–11 https://doi.org/10.1080/19338244.2018.1444575. J. Rong-Ming, G. Jian-Xin, Estimation of threshold limit value for dust in railway tunneling, Ind. Health Occup. Dis. 34 (3) (2008) 153–155 https://doi.org/10.1016/ S1005-8885(08)60096-5. G. Arcangeli, V. Cupelli, M. Montalti, M. Pristera, G. Giuliano, Respiratory risks in tunnel construction workers, Int. J. Immunopathol. Pharmacol. 17 (2 Suppl) (2004) 91–96 https://doi.org/10.1177/03946320040170S215. L.C. Oliver, H. Miracle-Mcmahill, Airway disease in highway and tunnel construction workers exposed to silica, Am. J. Ind. Med. 49 (12) (2006) 983–996 https:// doi.org/10.1002/ajim.20406. K. Chikao, F. Masami, M. Thosihiko, I. Jun-ichi, O. Kazuyo, Flow and dust concentration near working face of a tunnel under construction, J. Aerosol Sci. 31 (31) (2006) 31–32 https://doi.org/10.1016/S0021-8502(00)90037-5. L. Zhen, W. Xiao-Ling, C. Zheng-Fei, S. Rui-Rui, Z. Ai-Li, Simulation of construction ventilation in deep diversion tunnels using Euler–Lagrange method, Comput. Fluid 105 (2014) 28–38 https://doi.org/10.1016/j.compfluid.2014.09.016. S. Zhong-Qiang, S. Zhao-Gui, Study on dust diffusion regularity in tunnel slag process, Ind. Saf. Environ. Prot. 43 (2) (2017) 100–103 https://doi.org/10.3969/j. issn.1001-425X.2017.02.027. U. Bente, B. Berit, M. Erik, F. Per, K. Johny, B.L. May, Increased risk of obstructive pulmonary disease in tunnel workers, Thorax 55 (4) (2000) 277–282 https://doi. org/10.1136/thorax.55.4.277. B. Berit, S. Patricia, E. Wijnand, Determinants of dust exposure in tunnel construction work, Appl. Occup. Environ. Hyg 17 (11) (2002) 783–796 https://doi. org/10.1080/10473220290096032. S.G. Karen, M. Craig, A. Carla, D.V. Frank, V.T. Martie, Occupational exposure to respirable dust, respirable crystalline silica and diesel engine exhaust emissions in the London tunnelling environment, Ann. Occup. Hyg. 60 (2) (2016) 263–269 https://doi.org/10.1093/annhyg/mev067. G. Chun, S. Zhi-Tao, W. Ming-Nian, Study on the dust control of the construction environment safety in extra-long tunnel driven by TBM, Ind. Saf. Environ. Prot. 41 (7) (2015) 63–66 https://doi.org/10.3969/j.issn.1001-425X.2015.07.020. J. Liu, N. He, Wu Yin-Wen, J. Liu, Water jet vacuum dust suppression device used to tunnel development, Adv. Mater. Res. 594–597 (2012) 1188–1192 https://doi.org/ 10.4028/www.scientific.net/AMR.594-597.1188. X. Yu, Y. Dong-Hui, Z. Yu-Wei, Tunnel construction dust monitoring and dust control technology of high altitude and high and cold area, Appl. Mech. Mater. 587–589 (2014) 703–708 https://doi.org/10.4028/www.scientific.net/AMM.587589.703. J. Toraño, S. Torno, M. Menéndez, M. Gent, Auxiliary ventilation in mining roadways driven with roadheaders: validated CFD modelling of dust behaviour, Tunn. Undergr. Space Technol. 26 (1) (2011) 201–210 https://doi.org/10.1016/j.tust. 2010.07.005. L. Xin-Xiao, W. De-Ming, X. Chao-Hang, Z. Chao-Bing, S. Wei, Experimental investigation and field application of foam used for suppressing roadheader cutting hard rock in underground tunneling, Tunn. Undergr. Space Technol. 49 (2015) 1–8

Building and Environment 165 (2019) 106415

X. Chen, et al.

[56] Z. Zhi-Hui, W. Fan, Health impairment due to building construction dust pollution, J. Tsinghua Univ. 48 (6) (2008) 922–925 https://doi.org/10.3321/j.issn:10000054.2008.06.004. [57] L. Xiao-Dong, Z. Yi-Min, Z. Zhi-Hui, An LCA-based environmental impact assessment model for construction processes, Build. Environ. 45 (3) (2010) 766–775 https://doi.org/10.1016/j.buildenv.2009.08.010. [58] T. Rui-Peng, C. Peng-Cheng, Y. Xiao-Yi, Y. Yu-Yu, A. Yu, Uncertainty analysis of health damage of coal mine dust using the Monte Carlo method, J. Min. Sci. Technol. 2 (5) (2017) 467–474 https://doi.org/10.19606/j.cnki.jmst.2017.05.008. [59] T. Rui-Peng, Z. Ya-Bin, Y. Kai, W. Wen-Jun, Quantitative evaluation of coalmine dust health risk to miners in different working areas, China Saf. Sci. J. 23 (11) (2013) 102–107 https://doi.org/10.16265/j.cnki.issn1003-3033.2013.11.008. [60] World Health Organization Regional Office for Europ, Air quality guidelines for Europe. WHO regional publications, Eur. Ser. 23 (91) (1987) V https://doi.org/10. 1080/15287390701557834. [61] P. Hofstetter, Perspectives in life cycle impact assessment: a structured approach to combine models of the technosphere, ecosphere and valuesphere, Int. J. Life Cycle Assess. 5 (1) (1998) 58-58 https://doi.org/10.1007/BF02978561. [62] National Bureau of Statistics, Statistical bulletin of the development of China's health care industry in 2017, http://www.nhc.gov.cn/guihuaxxs/s10743/201806/ 44e3cdfe11fa4c7f928c879d435b6a18.shtml , Accessed date: 13 April 2019. [63] European Commission, New Elements for the Assessment of External Costs from Energy Technologies, Directorate-General for Research, Stuttgart, Germany, 2004. [64] W.K. Viscusi, E.A. Joseph, The value of a statistical life: a critical review of market estimates throughout the world, J. Risk Uncertain. 27 (1) (2003) 5–76 https://doi. org/10.2307/41761102. [65] National Bureau of Statistics, Statistical bulletin of national economic and social development in 2018, http://www.stats.gov.cn/tjsj/zxfb/201902/t20190228_ 1651265.html , Accessed date: 13 April 2019. [66] Bureau of Economic Analysis of the U.S. Department of Commerce, Gross domestic product, fourth quarter and annual 2018 (initial estimate), https://www.bea.gov/ news/2019/initial-gross-domestic-product-4th-quarter-and-annual-2018 , Accessed date: 13 April 2019. [67] Cumulative inflation calculator, https://inflationdata.com/Inflation/Inflation_ Calculators/Cumulative_Inflation_Calculator.aspx , Accessed date: 13 April 2019. [68] Chongqing Bureau of Statistics, Statistical bulletin of national economic and social development of chongqing in 2018, http://www.cqtj.gov.cn/bwtt/201903/ t20190319_454566.htm , Accessed date: 13 April 2019. [69] Ministry of Transport of the People's Republic of China, JTG F60-2009. Technical Specifications for Construction of Highway Tunnel. [70] T. Xin-Rong, C. Shou-Gen, Ma Hui, Application of air quality measuring in big and long tunnel construction, J. Saf. Environ. 12 (6) (2012) 103–107 https://doi.org/ 10.3969/j.issn.1009-6094.2012.06.023. [71] G. Wei, F. Hai-Lu, L. Wei, P. Wei, Z. Ai-Bin, G. Bao-Hong, Dust monitoring and causes analysis for acute poisoning of working staffs during Tianmushan tunneling, Tunn. Constr. 37 (5) (2017) 553–559 https://doi.org/10.3973/j.issn.1672-741X. 2017.05.005. [72] C. Gui, W. De-Ming, W. He-Tang, H. Fang-Wei, M. Yan, The technology of controlling dust with foam for fully mechanized excavation face of large cross-section rock tunnel, J. China Coal Soc. 37 (11) (2012) 1859–1864. [73] W. Qiu-Jun, Y. Li, X. Wen-Qiang, L. Qi, W. Ming-Nian, Study on the labor intensity classification standard for critical construction procedures of high-altitude tunnels, Mod. Tunn. Technol. 53 (6) (2016) 44–48 88 https://doi.org/10.13807/j.cnki.mtt. 2016.06.007. [74] Z. Min-Hua, W. Jun, G. Ming-Hua, Y. Hui-Ting, Z. Dong-Qing, On-site evaluation of respiratory protective equipment for workers exposed to dust, J. Environ. Occup. Med. 31 (4) (2014) 282–287 https://doi.org/10.13213/j.cnki.jeom.2014.0065. [75] L. Guo-Yun, L. Feng, W. Jia-Geng, G. Zi-Chen, G. Bao-Shi, Z. Rui-Hai, H. Feng, Occupational hazards and individual protection in a tunnel under construction and installation, J. Prev. Med. Chin. People's Liberation Army 35 (11) (2017) 1387–1389 https://doi.org/10.13213/j.cnki.jeom.2014.0065. [76] W. He-Tang, W. De-Ming, T. Yan, Q. Bo-Tao, X. Hai-Hui, Experimental investigation of the performance of a novel foam generator for dust suppression in underground coal mines, Adv. Powder Technol. 25 (3) (2014) 1053–1059 https://doi.org/10. 1016/j.apt.2014.02.011. [77] N. Wen, C. Wei-Min, Z. Gang, X. Jiao, C. Xiang-Fei, Research and application on external spray secondary dust falling device with negative pressure of roadheader, J. China Coal Soc. 39 (12) (2014) 2446–2452 https://doi.org/10.13225/j.cnki.jccs. 2013.1594. [78] Z. Yi-Kun, J. Zhong-An, S. Ya-Ru, Promotion effect of dust removal in heading face by ventilation duct with coanda effect, Saf. Coal Mines 48 (12) (2017) 161–163 https://doi.org/10.13347/j.cnki.mkaq.2017.12.043. [79] W. Hao, N. Wen, C. Wei-Min, L. Qiang, J. Hu, Effects of air volume ratio parameters on air curtain dust suppression in a rock tunnel's fully-mechanized working face, Adv. Powder Technol. 29 (2) (2017) 230–244 https://doi.org/10.1016/j.apt.2017. 11.007. [80] L. Ming-Hui, Q. Wei-Ming, W. Xiao-Wei, D. Cheng-Jun, Application of dust ventilator in guniting work 37 (2006), pp. 17–19 2 https://doi.org/10.3969/j.issn.1003496X.2006.02.006.

https://doi.org/10.1016/j.tust.2015.03.011. [31] L. Bao-Long, F. Jing-Guang, C. Sheng, G. Feng, L. Tie-Min, L. Zhan-Yuan, Studies on the application of logistic regression model to prediction and control of pneumoconiosis, China Saf. Sci. J. 11 (1) (2001) 40 https://doi.org/10.3969/j.issn.10033033.2001.01.009. [32] T. Dong-Mei, Y. Jian, J. Zhong-An, N. Wei, Z. Bin, Study on the risk assessment model for dusting operation sites, Metal. Mine (07) (2009) 122–126 https://doi. org/10.3321/j.issn:1001-1250.2009.07.038. [33] R. Dapari, H. Ismail, R. Ismail, N.H. Ismail, Application of fuzzy Delphi in the selection of COPD risk factors among steel industry workers, Tanaffos 16 (1) (2017) 46–52. [34] International Council on Mining & Metals, Good Practice Guidance on Occupational Health Risk Assessment, (2009). [35] T. Xiao-Ou, Z. Ya-Ling, L. Li-Tong, Application of LEC method in occupation health risk assessment of toner production enterprise, Chin. J. Public Health Mangement 32 (5) (2016) 652–654 https://doi.org/10.19568/j.cnki.23-1318.2016.05.024. [36] I.A. Bulavka, The development of a comprehensive assessment of occupational risk by taking into account the total hazard of working conditions, Gigiena i sanitariia (4) (2013) 47–54. [37] United States Environmental Protection Agency, Guidelines for Exposure Assessment, (1992). [38] N. Mohamad, M.T. Latif, M.F. Khan, Source apportionment and health risk assessment of PM10 in a naturally ventilated school in a tropical environment, Ecotoxicol. Environ. Saf. 124 (2016) 351–362 https://dx.doi.org/10.1016/j.ecoenv.2015.11. 002. [39] M. Joana, P. Inês, R. João, S. Milton, R. Elisabete, Source apportionment of CO2, PM10 and VOCs levels and health risk assessment in naturally ventilated primary schools in Porto, Portugal, Build. Environ. 96 (2016) 198–205 https://dx.doi.org/ 10.1016/j.buildenv.2015.11.031. [40] M. Othman, M.T. Latif, A.F. Mohamed, The PM10 compositions, sources and health risks assessment in mechanically ventilated office buildings in an urban environment, Air Qual Atmos. Health 9 (6) (2016) 597–612 https://dx.doi.org/10.1007/ s11869-015-0368-x. [41] L. Xiao-Dong, S. Su, H. Tian-Jian, Health damage assessment model for construction dust, J. Tsinghua Univ. 55 (1) (2015) 50–55 https://dx.doi.org/10.16511/j.cnki. qhdxxb.2015.01.009. [42] X. Hua-Li, Y. Jun, Q. Zhen-Zhen, L. Wan-Xiong, Z. Ting-Ting, L. Zhi-Cai, Health risk assessment of tunnel workers based on the investigation and analysis of occupational exposure to PM10, Environ. Sci. 36 (8) (2015) 2768–2774 https://dx.doi.org/ 10.13227/j.hjkx.2015.08.006. [43] H. Tian-Jian, The Monitoring and Analysis of the Health Damage Caused by Fugitive Dust in the Building Construction Phase, Tsinghua University, 2013. [44] National Health Commission of the People's Republic of China, GBZ 159-2004, Specifications of Air Sampling for Hazardous Substances Monitoring in the Workplace. [45] T. Xin-Rong, C. Shou-Gen, Z. Ze-Lin, Air quality field testing in tunnel construction with the drilling and blasting method, Chin. J. Undergr. Space Eng. 12 (2) (2016) 567–572. [46] S. Zhong-Qiang, Study on Dust Migration Regularity and Control Technology in Drilling and Blasting Method of Highway Tunnel Construction, University of Science and Technology, Beijing, 2015. [47] J. Jie, X. Jian-Lin, G. Yong-Yi, Analysis of coal mine dust concentration and particle size, J. Taiyuan Univ. Technol. 48 (4) (2017) 592–597 https://dx.doi.org/10. 16355/j.cnki.issn1007-9432tyut.2017.04.014. [48] General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China, GB2626-2006, Respiratory Protective Equipment-NoPowered Air-Purifying Particle Respirator. [49] G. Zi-Qing, Investigation and analysis on quality status of existing respiratory protective equipment in key industries, J. Saf. Sci. Technol. 12 (1) (2016) 154–157 https://dx.doi.org/10.11731/j.issn.1673-193x.2016.01.029. [50] X. Jun, L. Xiao-Dong, Z. Zhi-Hui, Daly-based health risk assessment of construction noise in Beijing, China, Int. J. Environ. Res. Public Health 13 (11) (2016) 1045 https://dx.doi.org/10.3390/ijerph13111045. [51] L. Xiao-Dong, S. Zi-Yang, Wang Tao, Z. Yu, N. Xin, Health impacts of construction noise on workers: a quantitative assessment model based on exposure measurement, J. Clean. Prod. 135 (2016) 721–731 https://doi.org/10.1016/j.jclepro.2016. 06.100. [52] Ministry of Ecology and Environment of the People's Republic of China, Exposure Factors Handbook Of Chinese Population (Adult Volume), first ed., China Environmental Science Press, Beijing, 2013. [53] G. Rice, J. Swartout, K. Mahaffey, R. Schoeny, Derivation of U.S.EPA's oral reference dose (RfD) for methylmercury, Drug Chem. Toxicol. 23 (1) (2000) 41–54 https://doi.org/10.1081/DCT-100100101. [54] W. Fu-Mei, C. Li, J. Jiao, Z. Lei-Bo, J. Ya-Qin, B. Zhi-Peng, Z. Li-Wen, S. Zeng-Rong, Pollution characteristics of phthalate esters derived from household dust and exposure assessment, China Environ. Sci. 32 (5) (2012) 780–786 https://doi.org/10. 3969/j.issn.1000-6923.2012.05.002. [55] T. Rui-Peng, C. Meng-Zhao, Z. Lei, L. Meng, Y. Xiao-Yi, L. Xiao-Dong, The construction dust-induced occupational health risk using Monte-Carlo simulation, J. Clean. Prod. 184 (2018) 598–608 https://doi.org/10.1016/j.jclepro.2018.02.286.

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