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Radon Exposure Assessment for Sewerage System's Workers in Naples, South Italy M. Pugliese, M. Quarto, F. De Cicco, C. De Sterlich and V. Roca Indoor and Built Environment 2013 22: 575 originally published online 13 December 2011 DOI: 10.1177/1420326X11431854 The online version of this article can be found at: http://ibe.sagepub.com/content/22/3/575

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Case Study Paper

Indoor and Built Environment

Indoor Built Environ 2013;22;3:575–579

Accepted: November 9, 2011

Radon Exposure Assessment for Sewerage System’s Workers in Naples, South Italy M. Pugliesea,b M. Quartoa C. De Sterlichd V. Rocaa,b

F. De Ciccob,c

a

Dipartimento di Scienze Fisiche, Universita` degli Studi di Napoli ‘‘Federico II’’, Italy Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Napoli, Italy c Dipartimento di Scienze Ambientali, Seconda Universita` degli Studi di Napoli, Italy d Servizio Prevenzione e Protezione, Comune di Napoli, Italy b

Key Words Effective dose E E-Perm detectors E Radon E Workplaces

Abstract An indoor radon survey has been carried out in 17 workplaces of sewerage system of Naples city using E-Perm detectors in long-term configuration. The main objective was to assess the mean effective dose for workers. The measured indoor radon concentration ranged from 1714 to 3789 Bq m3 in the rooms located on second level underground, from 138 to 5772 Bq m3 in the rooms on first level underground and from 53 to 913 Bq m3 in the ground floor. The mean annual effective doses in the ground floor, first and second level underground were found to be 0.85 mSv, 0.29 mSv and 0.43 mSv, respectively. These values are less than the lower limit of International Commission on Radiological Protection (ICRP) recommended action levels of 3–10 mSv y1.

ß The Author(s), 2011. Reprints and permissions: http://www.sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/1420326X11431854 Accessible online at http://ibe.sagepub.com

Introduction Environmental radon and its progeny contribute more than half to human exposure from natural sources [1–3]. Radon is a radioactive noble gas produced from the decay of uranium, which is found everywhere in the Earth’s crust, especially, in rocks, soil and underground water. A fraction of the radon escapes into the outdoor atmosphere where it is quickly diluted. On the contrary, in confined spaces such as homes and office buildings, radon can accumulate to harmful levels. Pooled analysis of epidemiological studies [4–8] has widely established that indoor radon and its decay products contribute significantly to an increased risk of lung cancer in general population [9]. Moreover, it is well known that the greater the exposure to radon, greater would be the risk of developing lung cancer. Really, after inhalation, radon is almost completely exhaled due to its long half-life (3.82 d), while its progenies, specially two radon daughters with short half-life, 218Po and 214Po, being electrically charged, can be attached to dust or

M. Quarto, Dipartimento di Scienze Fisiche, Universita` degli Studi di Napoli ‘‘Federico II’’, Italy. Tel. þ39 081 676151, Fax þ39 081 676257, E-Mail [email protected] Downloaded from ibe.sagepub.com by maria quarto on June 11, 2013

smoke particles in indoor air. During breathing process, they reach the bronchial tissue and there they decay emitting radioactive alpha particles capable of damaging the pulmonary epithelium and thereby causing lung cancer [10]. Many indoor concentrations of radon in dwellings and public buildings, such as schools and offices were surveyed in many countries [11–17]. Generally, basements and underground buildings that are in contact with soil would present highest radon concentration, so radon exposure of people working in underground spaces could be significant [3]. In Italy, according to the 96/29/EURATOM Directive of European Commission, the regulations for protection against ionizing radiations, Decreto Legislativo n. 241/ 2000 [18] provides the control and the limitation of the radon levels in all underground workplaces to prevent the exposure to natural radioactivity of workers. Actually, Italian legislation has imposed an action level for workplaces at 500 Bq m3 in accordance with the International Commission on Radiological Protection (ICRP 65) that recommends an action level within the range of 500–1500 Bq m3. With respect to exposure due to indoor radon at the underground workplaces, the Italian legislation has imposed the following rules: 1. if the average annual radon concentration is 4500 Bq m 3 and the effective annual dose to workers exceed 3 mSv, the workplace must be subjected to mitigation measure to reduce the indoor radon concentration using appropriate technologies; 2. if the average annual radon concentration is 4400 Bq m 3 (80% of action level), it is necessary to make further control in the following year and 3. if the average annual radon concentration is 5400 Bq m 3 the risk is considered limited and the workplace is exempted from further control and radiation-protection measures. In this study, radon measurements were performed in public underground workplaces, sewerage system of the city of Naples, Southern Italy. Moreover, effective annual dose due to radon were evaluated using United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) model for the workers.

Materials and Methods Measuring Sites Indoor radon concentrations were measured in 17 workplaces of sewerage system of Naples city. The examined

576

workplaces were located in different geographical locations in the city and their construction, at the end of nineteenth century with realization of sewerage, was placed on yellow tuff in west side and pozzolana in east side of the city. Three types of rooms, with different intended use, were monitored: the offices located generally at ground floor and tanks and pumps rooms located at first and second floor underground, respectively. In offices on the ground floor, the workers stay for 8 h day1, while in the tanks and pumps rooms in underground, the workers enter only for maintenance and repairs. All workplaces monitored were equipped with neither central heating nor air conditioning. Radon Measurements The radon measurements were carried out using the commercially available E-Perm detectors in long-term configuration (LLT) [19,20] (Rad. Ele. Inc., Frederck, Maryland, USA). The measuring device consists of a 50 mL conducting plastic chamber containing an electrostatically charged insulator (electret). Radon gas was passively diffused into the chamber through filtered inlets, and the alpha particles emitted by the radon and its daughters decay induced ionisation of the air molecules. The ions produced inside chamber were collected onto the surface of the electret generating a reduction of the charge on the surface. The electret charge decreased proportionally to the integrated radon concentration. The mean radon concentration measured by E-Perm would be sensible to indoor gamma radiation, so it was necessary to subtract the background gamma in order to avoid an overestimate of radon concentration. For this reason, all workplaces were monitored for gamma radiation by ionizing radiation (Berthold Technologies LB 1236, Germany). In the monitored rooms, the gamma dose rate (Ggamma) ranged between 0.18 and 0.45 mGy h1. In order to achieve the knowledge of its value, the loss of the electret charge was measured by an electrometer (Rad. Ele. Inc Mod. 6383 – 01, Frederck, Maryland, USA) and, using appropriate calibration factors and exposure time, the mean radon concentration was calculated using Equation (1): Vi Vf CRn ¼ Ggamma C1 37, ð1Þ CF T where CF ¼ C2 þ C3 (Vi þ Vf)/2. Vi and Vf are the initial and final electret voltages, respectively, T is the exposure time in days, Ggamma is the gamma background dose rate in mGy h1 and C1, C2 and C3 are constants that are given by the manufacturer and

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Pugliese et al.

they would depend on the E-Perm configuration and on the volume of the conducting plastic chamber. The experimental uncertainty of radon concentration measurement using E-Perm in LLT configuration depends on the gamma dose rate measurement, of the V value, of the exposure time and of the calibration factor and generally it is lower than 10% [21]. In each workplace, E-Perm detectors were exposed for two consecutive semesters and the radon annual average was calculated as an arithmetic mean between the values of the two semesters.

Results and Discussion A total number of 17 different workplaces were checked in this indoor radon survey of sewerage system of Naples. In nine workplaces, one room was monitored; in six workplaces, two rooms and in two workplaces, three rooms were monitored. The E-Perm detectors were installed in 21 tanks or pumps rooms on the first-floor underground, in four tanks or pumps rooms on the second-floor underground and in seven offices on ground floor. In Table 1, a description of them and the number of measures are reported. In each room, we exposed one detector per semester, for two consecutive semesters, and the measurements were performed from July 2008 to July 2009. In Table 2, the main statistical parameters obtained subdividing the data with respect to different floor levels are reported. Radon concentrations, as expected, are very high because all workplaces are located on the tuff rock. In particular, about 62% of radon concentrations in rooms on the first-floor underground of the workplaces surveyed exceeded the 500 Bq m3, which is the action level adopted for workplaces in Italian Regulation for Radiation Protection, while if we consider all measurements, 56% of indoor radon concentrations exceeded the action level. The results of radon survey were used to evaluate the annual mean effective dose H (mSv y1) to employees due to radon and its decay products exposure according to UNSCEAR model given by Equation (2):

Table 1. Description of the number of measurements in the workplaces examined Workplaces code

Name of workplaces

1 2 3 4

Taverna del Ferro Santa Lucia Piscinola Campodisola

5

Litoranea

6 7

La Pietra Piedigrotta

8 9 10

Botteghelle Coroglio Vigliena

11

Centro Direzionale

12 13 14 15

Marianella Rione Villa San Pasquale Galleria Vittoria

16

Mergellina

17

Villa Comunale

Number of rooms monitored/workplace

Floor levela

2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 3 1 3

1 0 1 1 2 0 1 2 1 0 1 2 1 1 0 1 0 1 0 1 1 0 1 1 2 1

a

0 ¼ ground floor, 1 ¼ first floor underground, 2 ¼ second floor underground.

where C is radon concentration (Bq m3), E is the equilibrium factor between radon and its decay products ( ¼ 0.6), F is the occupancy factor, T ¼ 8760 h y1 and

D ¼ 3 109 Sv per Bq m3 [9], which is the dose conversion factor. To determine the occupancy factor, different working hours were considered depending on the job category. An occupancy factor was set to 0.19 (i.e. 7 h per day, 5 days per week and 48 weeks per year) for employees who works on the ground level; and an occupancy factor of 0.01 (i.e. 0.5 h per day, 5 days per week and 48 weeks per year) for employees who works on the first- and second-floor underground. Using a mean value of 285 Bq m3 and assuming an occupancy factor of 0.19 for workplaces on the ground floor, an annual mean effective dose of 0.85 mSv y1 was determined. For workers on the first- and second-floor underground, the annual mean effective doses were estimated to be 0.29 mSv y1 and 0.43 mSv y1 assuming the mean values of 1868 Bq m3 and 2752 Bq m3, respectively (Table 3). These values are less than the recommended action level of 3 mSv y1 for the employees according to the Italian Regulation of Radiation Protection.

Radon Exposure Assessment for Workers in Naples


H ¼ C E F T D:

ð2Þ


577

Table 2. Summary of radon measurements in workplaces of sewerage system of Naples Floor level

N

AM SD (Bq m3)

GM (Bq m3)

GSD

Range (Bq m3)

4500 Bq m3

Second-floor underground First-floor underground Ground floor

4 21 7

2752 1122 1868 1816 285 294

2574 903 192

2440 898 181

1714–3789 138–5772 53–913

100% 62% 14%

N: number of measurements, AM: arithmetic mean, SD: standard deviation, GM: geometric mean, GSD: geometric standard deviation.

Table 3. Mean annual effective dose for workers in examined workplaces Floor level

N measures

Second-floor underground First-floor underground Ground floor

4 21 7

AM (Bq m3)

2752 1868 285

Effective dose (mSv y1) Mean

Range

0.43 0.29 0.85

0.27–0.60 0.02–0.91 0.15–2.70

Conclusion The mean effective annual dose was estimated due to radon concentration and their decay daughters for the workers of the sewerage system of Naples Municipality. The measurements were made on three different floors and the effective dose was estimated according to the different occupancy time on each floor. All the estimated effective doses delivered to the workers due to the indoor radon

were found to be less than the lower limit of ICRP recommended action levels of 3–10 mSv y1.

Acknowledgments The authors would like to thank staff members of Naples Municipality for their collaboration during the survey.

References 1 UNSCEAR-2000: United Nations Scientific Committee on the Effects of Atomic Radiation to the General Assembly: Sources, Effects and Risks of Ionizing Radiation. New York, United Nations, 2000. 2 WHO: Hand Book on Indoor Radon. The World Health Organization, Geneva, Switzerland, 2009. 3 Song MH, Chang BU, Kim Y, Cho KW: Radon exposure assessment for underground workers: a case of Seoul subway police officers in Korea: Radiat Prot Dosim 2011;147:401–405. 4 Lubin JH, Wang ZY, Boice JDJ, Zhao YX, Blot WJ, De Wang L, Kleinerman RA: Risk of lung cancer and residential radon in China: pooled results of two studies: Int J Cancer 2004;109:132–137. 5 Bochicchio F, Forastiere F, Farchi S, Quarto M, Axelson O: Residential radon exposure, diet and lung cancer: a case-control study in a Mediterranean region: Int J Cancer 2005;114:983–991.

578

6 Darby S, Hill D, Auvinen A, Barros-Dios JM, Baysson H, Bochicchio F, Deo H, Falk R, Forastiere F, Hakama M, Heid I, Kreienbrock L, Kreuzer M, Lagarde F, Makelainen I, Muirhead C, Oberaigner W, Pershagen G, Ruano-Ravina A, Ruosteenoja E, Schaffrath A, Tirmarche M, Tomascaronek L, Whitley E, Wichmann HE, Doll R: Radon in homes and lung cancer risk: collaborative analysis of individual data from 13 European case-control studies: Br Med J 2005;330:223–226. 7 Krewski D, Lubin JH, Zielinski JM, Alavanja M, Catalan VS, Field RW, Klotz JB, Le´ tourneau EG, Lynch CF, Lyon JI, Sandler DP, Schoenberg JB, Steck DJ, Stolwijk JA, Weinberg C, Wilcox HB: Residential radon and risk of lung cancer: a combined analysis of 7 North American case-controls studies: Epidemiology 2005;16(2):137–145. 8 Krewski D, Lubin JH, Zielinski JM, Alavanja M, Catalan VS, Field RW, Klotz JB, Le´ tourneau EG, Lynch CF, Lyon JL, Sandler DP, Schoenberg JB, Steck DJ, Stolwijk JA,



9

10

11

12

13

Weinberg C, Wilcox HB: A combined analysis of North American case–control studies of residential radon and lung cancer: J Toxicol Environ Health A 2006;69(7–8):533–597. ICRP-65: Protection against Rn-222 at home and at work. ICRP publication 65 Vol. 23/2: Ann of ICRP 1994. Abd El-Zaher M: Seasonal variation of indoor radon concentration in dwellings of Alexandria city, Egypt: Radiat Prot Dosim 2011;143(1):56–62. Venoso G, De Cicco F, Flores B, Gialanella L, Pugliese M, Roca V, Sabbarese C: Radon concentrations in schools of the Neapolitan area: Radiat Meas 2009;44:127–130. Rahman SU, Rafique M, Anwar MJ: Radon measurement studies in workplace buildings of the Rawalpindi region and Islamabad Capital area, Pakistan: Build Environ 2010;45:421–426. Rahman SU, Anwar MJ, Jabbar A, Rafique M: Indoor radon survey in 120 schools situated in four districts of the Punjab Province –

Pugliese et al.

Pakistan: Indoor Built Environ 2010;19(2):214–220. 14 Papachristodoulou CA, Patiris DL, Ioannides KG: Exposure to indoor radon and natural gamma radiation in public workplaces in north-western Greece: Radiat Meas 2010;45:865–871. 15 Rafique M, Rahman SU, Rahman S, Matiullah M, Shahzad I, Ahmed N, Iqbal J, Ahmed B, Ahmed T, Akhtar N: Assessment of indoor radon doses received by the students in the Azad Kashmir schools, Pakistan: Radiat Prot Dosim 2010;142(2–4):339–346.

16 Rahman SU, Rafique M, Anwara MJ: Radon measurement studies in workplace buildings of the Rawalpindi region and Islamabad Capital area, Pakistan: Build Environ 2010;45:421–426. 17 Llerena JJ, Cortina D, Dura´n V, Sorribas R: 222 Rn concentration in public secondary schools in Galicia (Spain): J Env Rad 2010;101:931–936. 18 Decreto Legislativo 26 maggio 2000, n.241 Allegato I bis comma 4 lettera a, Roma Italy, in Italian.

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19 Kotrappa P, Dempsey JC, Hickey JR, Stieff LR: An electret passive environmental 222Rn monitor based on ionization measurement: Health Phys 1988;54(1):47–56. 20 Kotrappa P, Dempsey JC, Ramsey RW, Stieff LR: A practical E-PERMTM (electret passive environmental radon monitor) system for indoor 222Rn measurement: Health Phys 1988;58(4):461–467. 21 E-Perm System Manual, Part I Appendix 4, 1-3. Rad. Elec. Inc., Frederick, Maryland, USA, 1994.



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