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Radon variations during treatment in thermal spas of Lesvos Island (Greece)
Journal of Environmental Radioactivity 76 (2004) 283–294 www.elsevier.com/locate/jenvrad
Radon variations during treatment in thermal spas of Lesvos Island (Greece) Efstratios Vogiannis b, Dimitrios Nikolopoulos a,, Anna Louizi a, Constantinos P. Halvadakis b a
Medical Physics Department, Medical School, University of Athens, Mikras Asias 75, 115 27 Goudi, Athens, Greece b Department of Environmental Studies, University of the Aegean, 81100 Mytilene, Greece Received 8 July 2003; received in revised form 18 November 2003; accepted 25 November 2003
Abstract The aim of this paper was to study the variations of radon and daughter nuclei during treatment in the thermal spas of Lesvos Island (Greece). For this purpose, in the thermal spas of Lesvos we have measured the radon concentrations of thermal waters, as well as indoor radon, daughter and coarse particle (>500 nm) concentrations. Various instruments and procedures were employed for measurements. Radon concentrations of thermal waters were found to lie in the range 10 Bq l1 and 304 Bq l1. Concentration peaks both for radon, radon daughter and coarse particle, were found to appear during filling of baths in the treatment process. The doses delivered to the bathers during treatment were in the range of 0.00670–0.1279 mSv per year, while the doses delivered to personnel were below 20 mSv per year. # 2004 Elsevier Ltd. All rights reserved. Keywords: Radon; Radon daughter; Thermal spas
1. Introduction The island of Lesvos is the third largest Greek island, located in the north-eastern part of the Aegean sea (1630 km2). Geologically recent great volcanic activity, which took place in Lesvos, have contributed to the formation of many hot springs in different places, some of which are used as healing baths (thermal spas) equipped with appropriate spa facilities.
Corresponding author. Tel.: +30-746-23-68; fax: +30-746-23-69. E-mail address: [email protected] (D. Nikolopoulos).
0265-931X/$ - see front matter # 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.jenvrad.2003.11.009
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Fig. 1. Thermal spas of Lesvos.
Radon and decay product nuclei present in indoor environment of spa facilities have been identified as an agent of additional radiation burden both for bathers and working personnel (Steinha¨usler, 1988; Datye et al., 1997). This additional burden has been studied by many researchers resulting in the introduction of appropriate health regulations (Bernhardt and Hess, 1996; Datye et al., 1997; Fitzgerald et al., 1997). However, for the spa facilities of Lesvos there exist no measurements for radon and decay product nuclei indoors. In addition, waters of the hot springs of Lesvos have been analysed only regarding geological, hydrogeological, geochemical and geophysical parameters (Papastamataki and Katsikatsos, 1969; Papastamataki, 1977; Papastamataki and Leonis, 1982, 1985; Fytikas et al., 1989; Michelot et al., 1993) and not for others such as concentration of radioactive elements, except for some measurements taken in the early 1930s (Pertesis, 1932). The aim of this study was to investigate the variations of radon and daughter nuclei during treatment in the thermal spas of Lesvos. Lesvos and its thermal spas are presented in Fig. 1. The spas were built in the areas of Eftalou, Loutra Thermis, Loutra Geras, Lisvori and Polichnitos.
2. Materials and methods Polichnitos, Eftalou and Lisvori contain two spa facilities. Loutra Thermis and Loutra Geras contain only one. All spa facilities under study comprise a treatment room (TR) and a reception room (RR) but the building structure differs. The two
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spas of Polichnitos and one of the two existing in Eftalou have been used for therapeutic purposes since Byzantine era. The TRs of these spas contain a bathtub of 8 m3 and are continuously ventilated via a number of small roof openings permanently open. The bathtub is filled once during a day. The RR is build beside the TR without separation. All other spa facilities were built during the last decade. The TRs of these spas contain bathtubs of about 1 m3. They are filled and emptied during a time period of 2–4 h. Additional rooms separated with doors also exist. One of these is used as an RR and the others for dressing and sanitary purposes. All rooms are ventilated through window openings. In every case, the spa personnel move through the various rooms but rest mainly in the RR. During the present study, the spa facilities of Lisvori were closed due to reconstruction and, therefore, not investigated. At the initial stage radon concentration measurements of the waters of the thermal spas of Lesvos were conducted in order to estimate their radon potential since no such measurements existed. The measurements were directed between the summer of 1999 and the summer of 2002. Sampling was performed at the water supply site of the spas, following strict protocol to avoid radon gas loss (Louizi et al., 2003). In the same time period, indoor radon and daughter nuclei concentrations were monitored in the indoor environment of spas. Moreover, coarse particle (>500 nm) indoor concentrations were measured. Water radon concentrations were measured using an Alpha Guard PQ2000Pro (Genitron GmbH) equipped with an appropriate unit (Aquakit), following a protocol proposed by the manufacturer (Genitron Instruments, 1994; 2000). Alpha Guard is an ionizing chamber which measures radon via alpha spectrometric techniques. For measurement with Aqua Kit, the water samples were forced to degas their radon content within a radon tight assembly, which consists of two glass vessels and the Alpha Guard unit. Indoor radon was monitored by Alpha Guard in 10 min data sampling cycles simultaneously with relative humidity. Monitoring of radon short-lived decay products indoors was performed by EQF3023 (Sarad Gbmh) in 2-h sampling cycles, simultaneously with radon measurements. The instrument performed separate measurements of attached and unattached progenies by properly rotating semiconductor measuring heads over a progeny collecting filter and a 50-nm mesh grid. For radon measurements, radon gas was pumped into a chamber and measured using a semiconductor sensor installed inside (Sarad Instruments, 1998). Coarse particle concentration measurements were performed by GRIMM 1.104 Portable Dust Monitor. In the spa facilities a set of indoor measurements was performed in an RR with EQF3023 without interfering with the operation procedure of the spa. Additionally, special procedures were followed so as to estimate concentration variations that may occur during treatment. In the RR of Polichnitos, Eftalou and Loutra Thermis facility, in the TRs of Polichnitos facilities and in one TR of the new spa facilities of Eftalou, Loutra Thermis and Loutra Geras, we have conducted indoor radon measurements with Alpha Guard PQ2000Pro, one set having the baths of every existing TR fully filled with thermal water and another set, after having emptied the thermal water from the baths of all existing TRs. Moreover, in one TR
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of the new facilities of Eftalou and Loutra Thermis, a bath was fully filled with thermal water, left filled for about 7 h and then emptied, while indoor measurements with all instruments were conducted for a period of about 1 day. In the TR of both facilities of Polichnitos the bath was fully filled with thermal water, left filled for about 24 h, emptied and filled again three times, while indoor measurements with all instruments were conducted. In addition, for a period of 1 day the bath in one of two TRs of Polichnitos was continuously filled with thermal water while it was simultaneously being emptied and measured.
3. Results and discussion Table 1 summarises thermal water radon measurement range of Lesvos spas together with average water temperature. Radon concentrations of thermal waters vary and are generally below 100 Bq l1, which is a limit, proposed by CEC (2001). The exceptions are the thermal waters of Polichnitos and Eftalou spas. The elevated concentrations of these spas indicated a rather high radon potential. Polichnitos and Lisvori thermal waters have high average temperatures, with those of Polichnitos to be the highest in Lesvos. The measured radon concentrations in thermal waters of Lesvos are within the range of measurements reported for other spas for Greece (Kritidis and Angelou, 1986; Danali-Cotsaki and Margomenou-Leonidopoulou, 1993; Trabidou et al., 1996). Vaupotic and Kobal (2001) reported very high concentrations in a swimming pool at Radenci Slovenia. Wider ranges are reported by others (Andrzej Przylibski, 2000; Horvath et al., 2000; Soto et al., 1995). Measurements conducted with EQF3023 without interfering in the operation procedure of the spas are presented in Table 2. In indoor environment of TRs of the facilities under study in which special procedures were followed, Figs. 2 and 3 present characteristic cases of radon and coarse particle concentration variations recorded by Alpha Guard 2000 Pro and GRIMM 1.104, respectively, and Fig. 4, a characteristic case of variations of radon and radon daughter concentration recorded by EQF3023. The overall indoor radon measurements in the RRs and TRs conducted with Alpha Guard PQ2000Pro are presented in Table 3. Elevated
Table 1 Range of radon concentrations and average temperatures of thermal waters of spas of Lesvos Location
Range of 222Rn concentration in water samples (Bq/l)
Average of water v temperature ( C)
Polichnitos Eftalou Lisvori Loutra Thermis Loutra Geras
126–202 113–304 12–17 13–22 10–16
76 40 64 41 39
n:d: ¼ no data:
Polichnitos (TR1) Eftalou (TR) Loutra Thermis (TR) Polichnitos (RR) Eftalou (RR)
Location
1100 2380 224 149 410
Rn-222 (Bq m3)
222 493 152 26.0 137
Po-218 attached (Bq m3)
Average concentration
64.0 188.0 10.0 14.7 32.2
Po-218 unattached (Bq m3) 138 442 120 27.4 159
Pb-214 attached (Bq m3) 5.1 11.6 4.09 3.80 3.85
Pb-214 unattached (Bq m3) 29.4 130 4.08 19.5 7.58
Bi-214 attached (Bq m3) 4.01 n.d. n.d. n.d. n.d.
Bi-214 unattached (Bq m3) 0.27 0.29 0.31 0.20 0.19
F-factor
2610 12300 1280 981 2740
PAEC (MeV/l)
Table 2 Measurements performed by EQF3023. Table presents also estimation of the equilibrium factor and the Potential Alpha Energy Concentration (PAEC). TR1 is the one of the two existing TRs in Polichnitos spa facility
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Fig. 2. Characteristic variations of radon concentrations in TRs recorded by Alpha Guard 2000 Pro in the spa facilities in which special procedures were followed. (a) Eftalou new TR fully filled with thermal water and left filled for 7 h. (b) Polichnitos TR1 fully filled with thermal water for 24 h emptied and filled again two times. In (a) the particle concentration is also presented.
indoor radon concentrations were measured in the spas of Polichnitos and Eftalou. This seems to be in accordance with the high radon potential of these spas, as detected from the measurements of their thermal waters. In the cases of Polichnitos and Eftalou, the average indoor radon concentration in the RR when all baths are being used is higher than the one when all baths are being emptied (Table 3). An explanation is that radon gas escapes from baths and enters the RR. Moreover, data measured in the RR by EQF3023 (Table 2) are significantly lower than those measured by Alpha Guard (Table 3). This fact could be attributed to the different measuring procedures followed by the two instruments. Remarkable is the fact that
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Fig. 3. Characteristic variations of radon concentrations in a TR of Eftalou new spa facilities recorded by Alpha Guard 2000 Pro, in which thermal water was continuously filled and poured out.
the average radon concentrations obtained from winter–spring measurements are less than those from summer–autumn (Table 3), especially for the case of Polichnitos spas. The average peak of Rn-222 concentrations in Eftalou TR shown in Table 3 are very high due to the special procedures followed. On the other hand, the radon concentrations in the RR of that spa facility (Tables 2 and 3) are lower due to the better ventilation of the RR. Peaks and decreases in daughter nuclei concentration are recorded. A time delay reach up to 4 h (Fig. 4) between radon peak and daughter peak concentration has been systematically observed for each progeny nuclei. The unattached fraction of radon progenies lies below 0.1% for each daughter nuclei and thus almost all progeny nuclei attach to coarse particles at their generation. In the TRs and RRs where EQF3023 was installed, effective doses were estimated using two conversion factors proposed by Porstendo¨rfer (2001). Considering the atmospheric conditions in therapy and reception rooms, these factors were chosen to be equal to 6:1 þ 42f p mSv per WLM for doses calculated in TRs and 5:4 þ 67f p mSv per WLM for doses calculated in RRs, where fp is the unattached fraction in terms of Potential Alpha Energy Concentration (PAEC) and which we defined as the ratio of the equivalent radon concentration attributed to unattached radon daughter nuclei over that attributed to all daughter nuclei. Potential Alpha Energy Exposure (PAEE) for personnel and bathers were calculated from PAEC values of Table 2, hypothesising that the bather delivers 30 treatments per year, each of which lasts 30 min and after which the bather rests in the RR for 2 h and the spa personnel is working 230 days per year for 8 h per day, namely 2 h in a TR
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Fig. 4. Characteristic variations of measurements in a TR performed with EQF 3023 in the indoor environment of the TR in Fig. 2a. (a) Radon concentration and equilibrium factor. (b) Attached and unattached 218Po concentration. (c) Attached and unattached 218Pb concentration. (d) Attached and unattached 218Bi concentration.
8.2 8.2 1.6 0.8 14
Polichnitos (TR1) Polichnitos (TR2) Eftalou new (TR) Loutra Thermis new (TR) Loutra Geras new (TR) Polichnitos (RR) Eftalou (RR) Thermi (RR)
c:f: ¼ continuous; flow n:d: ¼ no data:
Water volume (m3)
Location
1.5–3 1.5–3 3–8 0.5–2.5 c.f.
All baths being used (winter– spring) (Bq m3) 480 24 242 8 7260 357 187 22 192 21 346 20 842 42 27 4
All baths being empty (Bq m3)
102 6 94 4 117 7 56 4 35 4 98 5 107 6 42 4
1886 89 347 21 8263 396 243 32 221 25
All baths being used (summer– autumn) (Bq m3)
Peak duration (h)
Average Rn-222 concentration in the bath air
87 89 91 81 87 72 59 56
Air relative humidity (%)
5890 4784 315 35 n.d.
AM of coarse particles (lgm3)
Table 3 Indoor measurements with Alpha Guard 2000 Pro in the TRs of the spa facilities of Lesvos. The first column is the location of measurement, second is the bath volume, third is the indoor radon concentration in the TRs, fourth and fifth are the mean peak radon concentration during summer–autumn and winter–spring periods, sixth is the peak duration, seventh the relative humidity and eighth is the average concentration of the coarse particles during radon peak. TR1 and TR2 are the two existing TRs in Polichnitos spa facility
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Table 4 Annual exposure and dose calculations in the investigated spa facilities Users
Spa
Annual Annual Total annual Annual Annual Total exposure in exposure in exposure in dose in TR dose in annual TR (WLM) RR (WLM) spa (WLM) (mSv) RR (mSv) dose in spa (mSv)
Bathers
Eftalou Polichnitos Loutra Thermis
0.00835 0.00177
0.00744 0.00266
0.0158 0.00443
0.0763 0.0178
0.0516 0.0369
0.1279 0.0547
0.00869
n.d.
0.000869
0.00670
n.d.
0.00670
Eftalou Polichnitos Loutra Thermis
0.256 0.0621
0.171 0.0612
0.427 0.123
2.34 0.544
1.18 0.848
3.52 1.392
0.0266
n.d.
0.0266
0.205
n.d.
0.205
Workers
n:d: ¼ no data:
during filling and 6 h in the RR. 1 WL was considered to be equal to 1:3 105 MeV=l and 1 WLM equal to 170 WLH. The estimated doses are presented in Table 4. Doses estimated for bathers may be considered as low. On the other hand the corresponding doses for personnel are higher, but below 20 mSv per year which is a commonly accepted limit for workers (CEC, 2001). A typical time variation of this dose for one of the Polichnitos TRs is presented in Fig. 5.
Fig. 5. Dose rate delivered to a bather for the case of Fig. 2b. Continuous line was calculated from the data of Fig. 2b using a conversion factor of 9nSv/Bq h m3 proposed by UNSCEAR (2000).
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The dose values calculated indicate a short-term radiation burden both for bathers and working personnel which is delivered mainly while these reside in a TR of a spa. Nevertheless, this additional radiation burden may be considered as noticeable only for the working personnel. However, these doses are biased by the variability of the activity concentrations in environmental air with time. Therefore, the mean values of PAEC averaged over the measured time periods were used. This is in accordance with others (Lettner et al., 1996; Porstendo¨rfer, 1996). Moreover, the doses estimated are also biased by the differentiation in the definition of the unattached fraction in terms of PAEC given in this paper and in Porstendo¨rfer (2001). Based on our instrumentation, this definition was considered as the best approximation. Moreover, they are biased by the different ambient atmospheres found in the RRs and TRs studied compared to the standard atmospheric conditions proposed by Porstendo¨rfer (2001). In conclusion, bathing and working in Lesvos spas leads to intense variations of radon, radon daughter which consequently impose an additional health impact both to bathers and personnel. On the other hand, it is remarkable that such treatments may eventually impose positive results to the every-day life of the people using these thermal spas.
References Andrzej Przylibski, T., 2000. 222Rn concentration changes in medicinal groundwaters of Ladek Zdroj (Sudety Mountains, SW Poland). Journal of Environmental Radioactivity 48, 327–347. Bernhardt, G.P., Hess, C.T., 1996. Acute exposure from 222Rn and aerosols in drinking water. Environmental International 22, S753–S759. CEC (Commission of the European Communities), 2001. Commission Recommendation of 20 December 2001 on the Protection of the Public Against Exposure to Radon in Drinking Water Supplies, C(2001)/4580/01/928/EURATOM. Danali-Cotsaki, S., Margomenou-Leonidopoulou, G., 1993. 222Rn in Greek spa waters: correlation with rainfall and seismic activities. Health Physics 64(6), 605–612. Datye, V.K., Hopke, K., Fitzgerald, B., Raunemaa, A., 1997. Dynamic model for assessing 222-Rn and progeny exposure from showering with radon-bearing water. Environmental Science and Technology 31(6), 1589–1596. Fitzgerald, B., Hopke, K., Datye, V., Raunemaa, A., Kuuspalo, K., 1997. Experimental assessment of the short- and long-term effects of 22-Rn from domestic shower water on the dose burden incured in normally occupied homes. Environmental Science and Technology 31(6), 1822–1829. Fytikas, M., Kavouridis, T., Leonis, C., Marini, L., 1989. Geochemical exploration of the three most significant geothermal areas of Lesbos Island, Greece. Geothermics 18(3), 465–475. Genitron Instruments, 1994. Alpha Guard, Multiparameter Radon Monitor. Genitron Instruments Ltd, Frankfurt. Genitron Instruments, 2000. Alpha Guard PQ2000/MC50, Multiparameter Radon Monitor. Genitron Instruments Ltd, Frankfurt. Horvath, A., Bohus, L.O., Urbani, F., Marx, G., Piroth, A., Greaves, E.D., 2000. Radon concentrations in hot spring waters in northern Venezuela. Journal of Environmental Radioactivity 47, 127–133. Kritidis, P., Angelou, P., 1986. Concentrations of 222Rn and its short-lived decay products at a number of Greek radon spas. Nuclear Instruments and Methods in Physical Research B17, 537–539. Louizi, A., Nikolopoulos, D., Koukouliou, V., and Kehagia, K., 2003. Study of an area with enhanced radon concentrations. Radiation Protection Dosimetry 106(3), 219–226.
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Lettner, H., Hubmer, A.K., Rolle, R., Steinha¨usler, F., 1996. Occupational exposure to radon in treatment facilities of the radon-spa Badgastein, Austria. Environment International 22 (Suppl. 1), 399–407. Michelot, J.L., Dotsika, E., Fytikas, M., 1993. A hydorchemical and isotopic study of thermal waters on Lesvos Island (Greece). Geothermics 22(2), 91–99. Papastamataki A., and Katsikatsos, G., 1969. Thermal springs of Polichnitos. Report 1969. Institute of Geology and Mineral Exploitation Publication (in Greek). Papastamataki, A., 1977. The hot springs of Polichnitos. Report 1977. Institute of Geology and Mineral Exploitation Publication (in Greek). Papastamataki A., and Leonis, C., 1982. Geochemical prospecting for geothermal purposes, I. Lesvos district. Report 1982. Institute of Geology and Mineral Exploitation Publication (in Greek). Papastamataki, A., Leonis, C., 1985. The origin of Polichnitos hot springs. Geothermics: ThermalMineral Waters and Hydrogeology. Theophrastus Publications, S.A., Athens. Pertesis, M., 1932. Mineral waters in the island of Lesvos. Geological survey of Greece. Minsitry of National Economy, (in Greek). Porstendo¨rfer, J., 1996. Radon:measurements related to dose. Environment International 22 (Supp.1), 563–583. Porstendo¨rfer, J., 2001. Physical parameters and dose factors of the radon and thoron decay products. Radiation Protection Dosimetry 94(4), 365–373. Sarad Instruments, 1998. EQF3023 User Manual. Sarad Gbmh, Dresden. Soto, J., Fernandez, P.L., Quindos, L.S., Gomez-Arozamena, J., 1995. Radioactivity in Spanish spas. The Science of Total Environment 162, 187–192. Steinha¨usler, F., 1988. Radon spas: source term, doses and risk assessment. Radiation Protection Dosimetry 24, 257–259. Trabidou, G., Florou, H., Angelopoulos, A., Sakelliou, L., 1996. Environmental study of the radioactivity of the spas in the island of Ikaria. Radation Protection Dosimetry 63(1), 63–67. UNSCEAR, United Nation Scientific Committee on the Effects of Atomic Radiation, 2000. Sources and Effects of Ionizing Radiation. United Nations Publications, New York. Vaupotic, J., Kobal, I., 2001. Radon exposure in Slovenian spas. Radiation Protection Dosimetry 97(3), 265–270.
Radon variations during treatment in thermal spas of Lesvos Island (Greece) Efstratios Vogiannis b, Dimitrios Nikolopoulos a,, Anna Louizi a, Constantinos P. Halvadakis b a
Medical Physics Department, Medical School, University of Athens, Mikras Asias 75, 115 27 Goudi, Athens, Greece b Department of Environmental Studies, University of the Aegean, 81100 Mytilene, Greece Received 8 July 2003; received in revised form 18 November 2003; accepted 25 November 2003
Abstract The aim of this paper was to study the variations of radon and daughter nuclei during treatment in the thermal spas of Lesvos Island (Greece). For this purpose, in the thermal spas of Lesvos we have measured the radon concentrations of thermal waters, as well as indoor radon, daughter and coarse particle (>500 nm) concentrations. Various instruments and procedures were employed for measurements. Radon concentrations of thermal waters were found to lie in the range 10 Bq l1 and 304 Bq l1. Concentration peaks both for radon, radon daughter and coarse particle, were found to appear during filling of baths in the treatment process. The doses delivered to the bathers during treatment were in the range of 0.00670–0.1279 mSv per year, while the doses delivered to personnel were below 20 mSv per year. # 2004 Elsevier Ltd. All rights reserved. Keywords: Radon; Radon daughter; Thermal spas
1. Introduction The island of Lesvos is the third largest Greek island, located in the north-eastern part of the Aegean sea (1630 km2). Geologically recent great volcanic activity, which took place in Lesvos, have contributed to the formation of many hot springs in different places, some of which are used as healing baths (thermal spas) equipped with appropriate spa facilities.
Corresponding author. Tel.: +30-746-23-68; fax: +30-746-23-69. E-mail address: [email protected] (D. Nikolopoulos).
0265-931X/$ - see front matter # 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.jenvrad.2003.11.009
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E. Vogiannis et al. / J. Environ. Radioactivity 76 (2004) 283–294
Fig. 1. Thermal spas of Lesvos.
Radon and decay product nuclei present in indoor environment of spa facilities have been identified as an agent of additional radiation burden both for bathers and working personnel (Steinha¨usler, 1988; Datye et al., 1997). This additional burden has been studied by many researchers resulting in the introduction of appropriate health regulations (Bernhardt and Hess, 1996; Datye et al., 1997; Fitzgerald et al., 1997). However, for the spa facilities of Lesvos there exist no measurements for radon and decay product nuclei indoors. In addition, waters of the hot springs of Lesvos have been analysed only regarding geological, hydrogeological, geochemical and geophysical parameters (Papastamataki and Katsikatsos, 1969; Papastamataki, 1977; Papastamataki and Leonis, 1982, 1985; Fytikas et al., 1989; Michelot et al., 1993) and not for others such as concentration of radioactive elements, except for some measurements taken in the early 1930s (Pertesis, 1932). The aim of this study was to investigate the variations of radon and daughter nuclei during treatment in the thermal spas of Lesvos. Lesvos and its thermal spas are presented in Fig. 1. The spas were built in the areas of Eftalou, Loutra Thermis, Loutra Geras, Lisvori and Polichnitos.
2. Materials and methods Polichnitos, Eftalou and Lisvori contain two spa facilities. Loutra Thermis and Loutra Geras contain only one. All spa facilities under study comprise a treatment room (TR) and a reception room (RR) but the building structure differs. The two
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spas of Polichnitos and one of the two existing in Eftalou have been used for therapeutic purposes since Byzantine era. The TRs of these spas contain a bathtub of 8 m3 and are continuously ventilated via a number of small roof openings permanently open. The bathtub is filled once during a day. The RR is build beside the TR without separation. All other spa facilities were built during the last decade. The TRs of these spas contain bathtubs of about 1 m3. They are filled and emptied during a time period of 2–4 h. Additional rooms separated with doors also exist. One of these is used as an RR and the others for dressing and sanitary purposes. All rooms are ventilated through window openings. In every case, the spa personnel move through the various rooms but rest mainly in the RR. During the present study, the spa facilities of Lisvori were closed due to reconstruction and, therefore, not investigated. At the initial stage radon concentration measurements of the waters of the thermal spas of Lesvos were conducted in order to estimate their radon potential since no such measurements existed. The measurements were directed between the summer of 1999 and the summer of 2002. Sampling was performed at the water supply site of the spas, following strict protocol to avoid radon gas loss (Louizi et al., 2003). In the same time period, indoor radon and daughter nuclei concentrations were monitored in the indoor environment of spas. Moreover, coarse particle (>500 nm) indoor concentrations were measured. Water radon concentrations were measured using an Alpha Guard PQ2000Pro (Genitron GmbH) equipped with an appropriate unit (Aquakit), following a protocol proposed by the manufacturer (Genitron Instruments, 1994; 2000). Alpha Guard is an ionizing chamber which measures radon via alpha spectrometric techniques. For measurement with Aqua Kit, the water samples were forced to degas their radon content within a radon tight assembly, which consists of two glass vessels and the Alpha Guard unit. Indoor radon was monitored by Alpha Guard in 10 min data sampling cycles simultaneously with relative humidity. Monitoring of radon short-lived decay products indoors was performed by EQF3023 (Sarad Gbmh) in 2-h sampling cycles, simultaneously with radon measurements. The instrument performed separate measurements of attached and unattached progenies by properly rotating semiconductor measuring heads over a progeny collecting filter and a 50-nm mesh grid. For radon measurements, radon gas was pumped into a chamber and measured using a semiconductor sensor installed inside (Sarad Instruments, 1998). Coarse particle concentration measurements were performed by GRIMM 1.104 Portable Dust Monitor. In the spa facilities a set of indoor measurements was performed in an RR with EQF3023 without interfering with the operation procedure of the spa. Additionally, special procedures were followed so as to estimate concentration variations that may occur during treatment. In the RR of Polichnitos, Eftalou and Loutra Thermis facility, in the TRs of Polichnitos facilities and in one TR of the new spa facilities of Eftalou, Loutra Thermis and Loutra Geras, we have conducted indoor radon measurements with Alpha Guard PQ2000Pro, one set having the baths of every existing TR fully filled with thermal water and another set, after having emptied the thermal water from the baths of all existing TRs. Moreover, in one TR
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of the new facilities of Eftalou and Loutra Thermis, a bath was fully filled with thermal water, left filled for about 7 h and then emptied, while indoor measurements with all instruments were conducted for a period of about 1 day. In the TR of both facilities of Polichnitos the bath was fully filled with thermal water, left filled for about 24 h, emptied and filled again three times, while indoor measurements with all instruments were conducted. In addition, for a period of 1 day the bath in one of two TRs of Polichnitos was continuously filled with thermal water while it was simultaneously being emptied and measured.
3. Results and discussion Table 1 summarises thermal water radon measurement range of Lesvos spas together with average water temperature. Radon concentrations of thermal waters vary and are generally below 100 Bq l1, which is a limit, proposed by CEC (2001). The exceptions are the thermal waters of Polichnitos and Eftalou spas. The elevated concentrations of these spas indicated a rather high radon potential. Polichnitos and Lisvori thermal waters have high average temperatures, with those of Polichnitos to be the highest in Lesvos. The measured radon concentrations in thermal waters of Lesvos are within the range of measurements reported for other spas for Greece (Kritidis and Angelou, 1986; Danali-Cotsaki and Margomenou-Leonidopoulou, 1993; Trabidou et al., 1996). Vaupotic and Kobal (2001) reported very high concentrations in a swimming pool at Radenci Slovenia. Wider ranges are reported by others (Andrzej Przylibski, 2000; Horvath et al., 2000; Soto et al., 1995). Measurements conducted with EQF3023 without interfering in the operation procedure of the spas are presented in Table 2. In indoor environment of TRs of the facilities under study in which special procedures were followed, Figs. 2 and 3 present characteristic cases of radon and coarse particle concentration variations recorded by Alpha Guard 2000 Pro and GRIMM 1.104, respectively, and Fig. 4, a characteristic case of variations of radon and radon daughter concentration recorded by EQF3023. The overall indoor radon measurements in the RRs and TRs conducted with Alpha Guard PQ2000Pro are presented in Table 3. Elevated
Table 1 Range of radon concentrations and average temperatures of thermal waters of spas of Lesvos Location
Range of 222Rn concentration in water samples (Bq/l)
Average of water v temperature ( C)
Polichnitos Eftalou Lisvori Loutra Thermis Loutra Geras
126–202 113–304 12–17 13–22 10–16
76 40 64 41 39
n:d: ¼ no data:
Polichnitos (TR1) Eftalou (TR) Loutra Thermis (TR) Polichnitos (RR) Eftalou (RR)
Location
1100 2380 224 149 410
Rn-222 (Bq m3)
222 493 152 26.0 137
Po-218 attached (Bq m3)
Average concentration
64.0 188.0 10.0 14.7 32.2
Po-218 unattached (Bq m3) 138 442 120 27.4 159
Pb-214 attached (Bq m3) 5.1 11.6 4.09 3.80 3.85
Pb-214 unattached (Bq m3) 29.4 130 4.08 19.5 7.58
Bi-214 attached (Bq m3) 4.01 n.d. n.d. n.d. n.d.
Bi-214 unattached (Bq m3) 0.27 0.29 0.31 0.20 0.19
F-factor
2610 12300 1280 981 2740
PAEC (MeV/l)
Table 2 Measurements performed by EQF3023. Table presents also estimation of the equilibrium factor and the Potential Alpha Energy Concentration (PAEC). TR1 is the one of the two existing TRs in Polichnitos spa facility
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Fig. 2. Characteristic variations of radon concentrations in TRs recorded by Alpha Guard 2000 Pro in the spa facilities in which special procedures were followed. (a) Eftalou new TR fully filled with thermal water and left filled for 7 h. (b) Polichnitos TR1 fully filled with thermal water for 24 h emptied and filled again two times. In (a) the particle concentration is also presented.
indoor radon concentrations were measured in the spas of Polichnitos and Eftalou. This seems to be in accordance with the high radon potential of these spas, as detected from the measurements of their thermal waters. In the cases of Polichnitos and Eftalou, the average indoor radon concentration in the RR when all baths are being used is higher than the one when all baths are being emptied (Table 3). An explanation is that radon gas escapes from baths and enters the RR. Moreover, data measured in the RR by EQF3023 (Table 2) are significantly lower than those measured by Alpha Guard (Table 3). This fact could be attributed to the different measuring procedures followed by the two instruments. Remarkable is the fact that
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Fig. 3. Characteristic variations of radon concentrations in a TR of Eftalou new spa facilities recorded by Alpha Guard 2000 Pro, in which thermal water was continuously filled and poured out.
the average radon concentrations obtained from winter–spring measurements are less than those from summer–autumn (Table 3), especially for the case of Polichnitos spas. The average peak of Rn-222 concentrations in Eftalou TR shown in Table 3 are very high due to the special procedures followed. On the other hand, the radon concentrations in the RR of that spa facility (Tables 2 and 3) are lower due to the better ventilation of the RR. Peaks and decreases in daughter nuclei concentration are recorded. A time delay reach up to 4 h (Fig. 4) between radon peak and daughter peak concentration has been systematically observed for each progeny nuclei. The unattached fraction of radon progenies lies below 0.1% for each daughter nuclei and thus almost all progeny nuclei attach to coarse particles at their generation. In the TRs and RRs where EQF3023 was installed, effective doses were estimated using two conversion factors proposed by Porstendo¨rfer (2001). Considering the atmospheric conditions in therapy and reception rooms, these factors were chosen to be equal to 6:1 þ 42f p mSv per WLM for doses calculated in TRs and 5:4 þ 67f p mSv per WLM for doses calculated in RRs, where fp is the unattached fraction in terms of Potential Alpha Energy Concentration (PAEC) and which we defined as the ratio of the equivalent radon concentration attributed to unattached radon daughter nuclei over that attributed to all daughter nuclei. Potential Alpha Energy Exposure (PAEE) for personnel and bathers were calculated from PAEC values of Table 2, hypothesising that the bather delivers 30 treatments per year, each of which lasts 30 min and after which the bather rests in the RR for 2 h and the spa personnel is working 230 days per year for 8 h per day, namely 2 h in a TR
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Fig. 4. Characteristic variations of measurements in a TR performed with EQF 3023 in the indoor environment of the TR in Fig. 2a. (a) Radon concentration and equilibrium factor. (b) Attached and unattached 218Po concentration. (c) Attached and unattached 218Pb concentration. (d) Attached and unattached 218Bi concentration.
8.2 8.2 1.6 0.8 14
Polichnitos (TR1) Polichnitos (TR2) Eftalou new (TR) Loutra Thermis new (TR) Loutra Geras new (TR) Polichnitos (RR) Eftalou (RR) Thermi (RR)
c:f: ¼ continuous; flow n:d: ¼ no data:
Water volume (m3)
Location
1.5–3 1.5–3 3–8 0.5–2.5 c.f.
All baths being used (winter– spring) (Bq m3) 480 24 242 8 7260 357 187 22 192 21 346 20 842 42 27 4
All baths being empty (Bq m3)
102 6 94 4 117 7 56 4 35 4 98 5 107 6 42 4
1886 89 347 21 8263 396 243 32 221 25
All baths being used (summer– autumn) (Bq m3)
Peak duration (h)
Average Rn-222 concentration in the bath air
87 89 91 81 87 72 59 56
Air relative humidity (%)
5890 4784 315 35 n.d.
AM of coarse particles (lgm3)
Table 3 Indoor measurements with Alpha Guard 2000 Pro in the TRs of the spa facilities of Lesvos. The first column is the location of measurement, second is the bath volume, third is the indoor radon concentration in the TRs, fourth and fifth are the mean peak radon concentration during summer–autumn and winter–spring periods, sixth is the peak duration, seventh the relative humidity and eighth is the average concentration of the coarse particles during radon peak. TR1 and TR2 are the two existing TRs in Polichnitos spa facility
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Table 4 Annual exposure and dose calculations in the investigated spa facilities Users
Spa
Annual Annual Total annual Annual Annual Total exposure in exposure in exposure in dose in TR dose in annual TR (WLM) RR (WLM) spa (WLM) (mSv) RR (mSv) dose in spa (mSv)
Bathers
Eftalou Polichnitos Loutra Thermis
0.00835 0.00177
0.00744 0.00266
0.0158 0.00443
0.0763 0.0178
0.0516 0.0369
0.1279 0.0547
0.00869
n.d.
0.000869
0.00670
n.d.
0.00670
Eftalou Polichnitos Loutra Thermis
0.256 0.0621
0.171 0.0612
0.427 0.123
2.34 0.544
1.18 0.848
3.52 1.392
0.0266
n.d.
0.0266
0.205
n.d.
0.205
Workers
n:d: ¼ no data:
during filling and 6 h in the RR. 1 WL was considered to be equal to 1:3 105 MeV=l and 1 WLM equal to 170 WLH. The estimated doses are presented in Table 4. Doses estimated for bathers may be considered as low. On the other hand the corresponding doses for personnel are higher, but below 20 mSv per year which is a commonly accepted limit for workers (CEC, 2001). A typical time variation of this dose for one of the Polichnitos TRs is presented in Fig. 5.
Fig. 5. Dose rate delivered to a bather for the case of Fig. 2b. Continuous line was calculated from the data of Fig. 2b using a conversion factor of 9nSv/Bq h m3 proposed by UNSCEAR (2000).
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The dose values calculated indicate a short-term radiation burden both for bathers and working personnel which is delivered mainly while these reside in a TR of a spa. Nevertheless, this additional radiation burden may be considered as noticeable only for the working personnel. However, these doses are biased by the variability of the activity concentrations in environmental air with time. Therefore, the mean values of PAEC averaged over the measured time periods were used. This is in accordance with others (Lettner et al., 1996; Porstendo¨rfer, 1996). Moreover, the doses estimated are also biased by the differentiation in the definition of the unattached fraction in terms of PAEC given in this paper and in Porstendo¨rfer (2001). Based on our instrumentation, this definition was considered as the best approximation. Moreover, they are biased by the different ambient atmospheres found in the RRs and TRs studied compared to the standard atmospheric conditions proposed by Porstendo¨rfer (2001). In conclusion, bathing and working in Lesvos spas leads to intense variations of radon, radon daughter which consequently impose an additional health impact both to bathers and personnel. On the other hand, it is remarkable that such treatments may eventually impose positive results to the every-day life of the people using these thermal spas.
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