Romanian Reports in Physics 73, 801 (2021)

NATURAL THERAPEUTIC FACTORS ASSESSMENT FOR THE USE IN SPELEOTHERAPEUTIC PURPOSES OF THE SALINE MINE,

MARIAN ROMEO CALIN1*, IURI GHEORGHE SIMIONCA2, ILEANA RADULESCU1 1 “Horia Hulubei” National Institute for Physics and Nuclear Engineering-IFIN-HH, 30 Reactorului Street, P.O. Box MG-6, 077125, Magurele, Romania * Coresponding author e-mail: [email protected] 2 National Institute of Rehabilitation, Physical and Balneoclimatology, -INRMFB, Romania E-mail: [email protected] Received July 16, 2020

Abstract. Salt mine galleries possess different therapeutic factors that can be used in the treatment of patients with multiple disorders and balneo-climatic underground tourism purposes. The paper presents the characterization from the point of view of radioactivity, the atmospheric radon and gamma radiations dose, and the results of microclimatic investigations the salt mine aerosols, microorganisms and gases concentrations – speleo-therapeutic factors, usable for medical and balneo- climatic tourism purposes in the galleries of Cacica salt mine, County, Romania. The mean radon concentration at six different locations within the salt mine varied between 20.5 and 96.5 Bq/m3. A seasonal variation was observed, with higher radon levels during summer and lower values during the winter season. The concentration of the aero-ions, the aerosol dispersion, the concentration of microorganisms, concentration of different gases in the underground, in galleries from Cacica salt mine are also presented.

Key words: radon concentration, radiological and dosimetric measurements, speleotherapy, salt mines, speleotherapeutic factors.

1. INTRODUCTION

Romania is one of the richest European countries in natural deposits of salts and salt mines, some of them forming massive salt domes, which result from high pressure, that pushes the salt up through the rocks from great depths [1]. Salt mines are also tourist targets, as well as real destinations for speleotherapy. Some salt mines are designed to provide the speleotherapeutic treatment that the human body needs. Due to the low level of natural radioactivity, compared to other geological formations, rock salt mines have a suitable environment for speleotherapeutic use, including prevention, treatment and recovery of patients with some chronic respiratory, Article no. 801 Marian Romeo Calin et al. 2 and allergic pathologies (chronic obstructive bronchitis, bronchial asthma), as well as rheumatic ones [2], but also for spa tourism and other curative applications. Thus, speleotherapy in some salt mines represents a potential of solutions for optimizing health services and for increasing the level of life quality. Radon is one of the speleotherapeutic factors. Radon, to a small extent, can be used in therapy and has beneficial effects on inflammation and pain. Radon therapy is efficient in the treatment of various diseases associated with: the nervous system, the locomotor system, the cardiovascular system, the respiratory, gynaecological and digestive organs, the endocrine, the urological, skin and blood vessels. Radon is one of the most important contributors to human exposure from natural radiation sources. Generally, radon tends to accumulate in underground spaces, because it is heavier than air and emanates from rocks and soils. Radon (222Rn) and its short-life decay products (218Po, 214Pb, 214Bi and 214Po) and Thoron (220Rn) and its daughters (216Po, 212Pb, 212Bi and 212Po) are alpha, beta and gamma-emitting nuclei. The inhalation of these radionuclides, which occurs in the free atmosphere and in indoor air, represents the main source of exposure to ionizing radiation for the population of most countries. Speleotherapy (the use of underground environments as a medical alternative), is a therapeutic method in the treatment of chronic airways diseases. It is virtually unknown in the USA or the UK, but it is considerable widespread in several Central and Eastern European countries. This method is a relatively new method of complementary medicine, being accepted as speleotherapy (ST). Although has been officially known since the 1950–1960, in Germany and Poland only in the last years ST in salt mines and caves has become a practice in Europe [2–9].

1.1. CLIMATE, SEASONS AND GEOLOGY OF STUDIED AREA

The Cacica salt mine is situated in the (Figs. 1 and 2), Bucovina region, a great tourist value area, known at the national and international level. According to archaeological research conducted in 1952, 1968 and 1989 in Cacica, both use of salt water springs in their natural state and for the production of salt recrystallized by boiling have a millennial age. Based on archeological material, Cacica salt mine has been attested as one of the oldest recrystallized salt mines in brine in Europe, dating from the 5th millennium B.C., from the period of the culture from the early Neolithic. Cacica salt mine it is situated in the north-east part of the Romania, at 42 km west from Suceava town and the 17 km north from . Due to the beauty of nature and the air strongly ozonized, make from this place an attractive destination in any season, for rest, pleasure and the treatment of respiratory disorders. The subterranean environment in Cacica salt mine contains salt aerosols, that is natural andaseptic, less polluted and not allergic, the total number of germs being of 110–1426/m3 air [6–9].

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Fig. 1 – Investigated Cacica salt mine test areas on Fig. 2 – Geographical location of the Romania’s map. Cacica salt mine.

Fig. 3 – Underground experimental speleo- Fig. 4 – Measurements carried out in one of the therapeutic sections in Gallery 1 designed selected points inside of the studied Cacica salt for speleotherapy and recreation, Old salt Mine, mine with PYLON AB 5 system equipped with Cacica salt mine (Photo by C. Zup & Lucas cell. I. Simionca [9]).

It was observed that the microclimate of the salt mines in Romania has a thermo-hygrico-baric constant (temperature 10 ÷ 12°C, relative humidity 60 ÷ 75%, atmospheric pressure – depending on the air pressure outside) and a velocity of air currents less than 0.1 m/s, inside the underground rooms, and about 0.3–0.4 m/s, near the air vents. Aero-ionization in the field of small ions is slightly moderate, with a tendency towards predominance of positive ions, and the concentration of large ions is relatively higher, with the predominance of negative ions. The aerosol particle concentration is high, but different, with 80–95% of particles below 3 µm [10].

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The microbiological determinations reveal a pure air, the concentrations of microorganisms being minimal in the underground environment of some salt mines galleries [9, 10]. The aim of this work was to elaborate new and innovative technical solutions for the measurement and characterization of the environment with potentially curative, find salt mines parameters for the proper medical-speleotherapeutical and balneary tourism. The investigations in the Cacica salt mine were carried out within the project – Medical-biological complex study in view of an innovative use of the environment potential therapeutic factors in salt mines and caves for health and balneo-climateric tourism; solutions to improve these [9] (Figs. 3 and 4).

2. MATERIALS AND METHODOLOGY

2.1. MEASUREMENT OF RADON CONCENTRATION

The locations of measuring points and the environmental conditions are presented in Table 1. The analyses were carried out in several areas of the Cacica salt mine, according to Tables 2–3, for 10 minutes time intervals, at different points of three floors of the mine (Salt Lake, Dance Hall and Gym Hall) and at the access point into the salt mine as referece location. In these locations, the radon concentration was measured in high ventilation conditions. Continuous radon gas measurements and decay products concentration measurements were carried out for several years in different seasons (Table 3). The measuring devices was a Pylon model AB-5 portable radon monitor for radon gas and decay products (Fig. 4) equipped with a model CPRD passive scintillation cell detector [ZnS(Ag)]–Lucas cell. The radon concentrations for the predetermined interval were stored in the instrument’s memory and transmitted subsequently to a computer. This system was used in continuous mode using the calibration factor of S = 421 × 10–4 ± 4% CPM/(Bq × m–3) [11–17]. The radon concentration was calculated using the following relation: –3 CRn = ((CPM/INT) – BG)/S, where: CRn is the radon gas concentration (Bq × m ); CPM is the number of counts for the interval; INT represents the time interval (min), BG stands for the background (in cpm) and S is the sensivity (the calibration factor) [11–17]. The measuring of the natural background ionizing radiation in the Cacica salt mine was conducted using the Berthold Umo LB 123 portable integrated impulse debit meter (used in rate mode) equipped with a gamma probe – Counter- timer with a integration time of 3600 s/measure.

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Table 1 Location of the measurement points and environmental conditions

MEASURIG AVERAGE AVERAGE DEPTH AVERAGE AVERAGE No AREA/ TEMPERA WIND [m] PRESSURE HUMIDITY LOCATION TURE SPEED [hPa] [%] [oC] [m/s] CONDITIONS VENTILATION COORDINATES 1. Salt Lake 32 10.2 1008.0 70 0.5 Without 2. Dance Hall 37 10.4 1008.5 72 0.4 ventilation 3. Gym Hall 63 12.5 1009.4 73 0.3 4. With Dance Hall 37 11.5 1009.3 68 1.1 5. ventilation Gym Hall 63 11.1 1009.2 71 1.2 Access point 25°53’52.55" E 25°53’52.55" 6. – into the salt – 21.0 1009.6 74 1.6 N 47°38’06.51" mine

The measurement and calibration procedures were conducted in compliance with the procedures of the accredited SALMROM laboratory (System Calibration Report, SALMROM Quality Manual, SR EN ISO/CEI 17025:2018). The measurements were performed in both poorly and highly ventilated conditions. The data recorded in the first 3.5 hours were not taken into account because this time is necessary for the system to reach its equilibrium point. All calculations were performed taking into account the measured natural background radiation of 0.2 cpm. From the bioclimatic point of view the investigated galleries show discomfort through cooling, the air temperatures are quite low 10.2 ÷ 12.5°C. In Capela, Dance Hall, Sport Hall, the additional galleries 1, 2, 3 and 4 from the Cacica salt mine, were the smallest values of the air currents (below 0.1 m/s) – potentially stimulating conditions of the adaptation processes to the environment. The difference of atmospheric pressure in the underground galleries in the Cacica salt mine in comparison with the surface data is between 6 ÷ 7 mm Hg.

3. DATA ANALYSIS

3.1. DATA ANALYSIS OF RADON CONCENTRATION

In order to analyse the most appropriate measurement places, different criteria were taken into account: representative points of the geology of the salt mine, exchange of air, work places inside the salt mine (Salt Lake, Dance Hall, Gym Hall) and more frequently visited places by tour tourists and guides. The acquired data were transferred to a computer using the specialized software Transfer Utility 1.1. The data were processed subsequently with Windows

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Excel software. The calculated errors were: S(n – 1) – experimental standard deviation, S(n – 1) [%] – relative experimental standard deviation, S(med) – experimental standard deviation of the mean, S(med) [%] – relative experimental standard deviation; S(Poisson) – Poisson relative error, global absolute error. S(Poisson) is given for comparison with the value of the standard deviation on the average value, for the purpose of statistical assessment of the average values versus the total number taken (Fig. 5) [11–17].

Fig. 5 – Time dependence of radon concentration in Cacica salt mine (Salt Lake, 32 m depth).

For example, the results of continuous radon concentrations measurements for a period of september 2010 at the Salt Lake of Cacica salt mine are presented in Fig. 5, in which the diurnal and nocturnal variations are observed. The indoor radon concentrations are the bigger in rainy and winter seasons and the lowest in summer season. In general, indoor radon concentrations in the studied area are lower than the recommended action level of 300 Bq × m–3. It can be observed that the radon concentrations exhibit temporal variations from 56.5  3.8 Bq/m3 to 37.2  4.8 Bq/m3 with an average radon concentration of 47.2  4.8 Bq/m3 (in Salt Lake), 57.6  4.2 Bq/m3 (in Dance Hall), 54.9  4.8 Bq/m3 (in Gym Hall) – without ventilation, etc. (Table 3). The background dose rate was 16  0.03 nSv/h. In the outdoor environments, at the access point into the salt mine, the radon is dispersed in the atmosphere and the average radon concentration has become 26.3  2.1 Bq/m3 (Table 3). In this place, the background dose rate was 127  0.07 nSv/h. The average radon concentrations for all the measuring locations are presented in Table 2. From the point of view of radioactivity and the concentrations of radionuclides in the investigated locations of the salt mine, these were around the minimum detectable

7 Natural therapeutic factors assessment for the use in speleotherapeutic Article no. 801 or below. Thus, the natural radiation background in the Cacica salt mine was found to be 16 nSv/h with small differences in other locations (Dance Hall, Underground Lake, Sports Hall), and on the surface of 127 nSv/h with an error of 5.2%.

Table 2 The average radon concentration in the poorly ventilated enclosed environment from Cacica salt mine

AVERAGE

MEASURING RADON Error S(n–1) S(n–1) S(med) S(med) S(Poisson) POINT/ CONCENTRA- No. [Bq/m3] [Bq/m3] [%] [Bq/m3] [%] [%] LOCATION TION 3

[Bq/m ] CONDITIONS VENTILATION Salt Lake 1. (swimming 47.2 ± 4.8 4.76 17.37 18.00 2.78 2.88 1.73 pool) 2. Dance Hall 57.6 ± 4.2 4.22 11.36 11.97 1.84 1.94 1.77 3. Gym Hall 54.9 ± 4.8 5.21 8.85 9.44 3.61 3.85 4.48 Access point 4. into the salt 40.1 ± 4.1 1.30 2.03 9.90 1.01 4.95 1.85 mine ventilation Without 5. Dance Hall 40.9 ± 4.2 4.76 9.62 18.94 4.30 8.47 6.54

6. Gym Hall 26.3 ± 2.1 5.16 10.45 11.58 3.69 4.09 3.95 With ventilation ventilation

Therefore, in the investigated galleries of the Cacica salt mine the radiation background was about 8 times smaller than on the surface. In the new locations of the Cacica salt mine (rooms 1, 2, 3 and 4) there is a radiation background ranging on average from 5 nSv/h (err. 6.0%) to 6 nSv/h (err. 7.2%), about 20 times smaller than the surface. The results presented in Table 2 show that the radon concentration in Cacica salt mine is approximately constant in all studied locations. The small radon concentration variations are due to emanation, exhalation and the salt mine climate (Table 1). Emanation is the net radon production rate in the rock walls of salt mine or water, and depends on the concentration of natural radionuclide’s of uranium and thorium in the material [18–21]. Exhalation is the proportion of radon produced that is released into the atmosphere and is affected by the wall porosity, temperature, and variations in atmospheric pressure and humidity. Temperature and humidity may both enhance and inhibit the transport of radon from the walls or water to ambient air. The radon concentration may be temporarily decreased by the usage of ventilation systems. Using ventilation installation at the Cacica salt mine has resulted in a decrease of the average radon concentration from 94.9 Bq/m3 to 50.8 Bq/m3 in Dance Hall and respectively from 93.8 Bq/m3 to 90.2 Bq/m3 in Gym Hall (Table 2). In both cases, with or without ventilation, the radon levels in the

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Cacica salt mine are 3 times higher than the values of radon levels in the atmosphere reported by UNSCEAR (2000, 2006) [22, 23] for Romania. These radon levels are lower in comparison to those reported for mines, caves or spas in other countries where speleotherapy is frequently applied. However, the accumulation of radon in the environmental conditions present in the Cacica salt mine can be fructified by Romanian researchers from interdisciplinary fields (medicine, biology, physics, immunology, etc.) for the national development of radon therapy and speleotherapy. Table 3 shows the averages of radon concentrations over a period of 5 years (2009–2013) based on the study in the same measurement areas of the salt mine. The averages of these concentrations are between 26.3 and 57.6 Bq/m3.

Table 3 Average radon concentration in Cacica salt mines for the period 2009–2013

3 LOCATION/ Average Radon Concentration [Bq/m ] Average No. MEASURING [Bq/m3] POINT/ July 2009 Sept. 2010 Oct. 2011 Oct. 2012 Nov. 2013 Location Salt Lake 1. 56.5 ± 3.8 47.2 ± 4.8 37.7 ± 3.4 39.3 ± 3.5 44.7 ± 4.1 47.2 ± 4.8 (Swimming pool) Dance Hall 2. 64.9 ± 4.2 64.5 ± 3.7 53.5 ± 4.5 51.5 ± 4.2 53.2 ± 4.3 57.6 ± 4.2 (No ventilation) Gym Hall 3. 63.8 ± 5.1 63.3 ± 5.2 49.7 ± 4.7 48.2 ± 4.1 49.7 ± 5.2 54.9 ± 4.8 (No ventilation) Dance Hall 4. 50.8 ± 4.8 40.8 ± 4.7 33.4 ± 3.5 36.8 ± 3.7 38.7 ± 3.4 40.1 ± 4.1 (With ventilation)

Cacica saltmine Gym Hall 5. 50.2 ± 5.1 52.5 ± 5.4 31.2 ± 3.2 34.2 ± 3.4 36.5 ± 3.7 40.9 ± 4.2 With ventilation Access point into 6. 25.5 ± 1.3 23.5 ± 1.5 27.6 ± 2.4 25.7 ± 2.3 29.2 ± 2.8 26.3 ± 2.1 the salt mine

3.2. GAMMA SPECTROMETRIC MEASUREMENTS ON SALT SAMPLES

The experimental measurements were performed using an Ortec detector with GeHP, with the following installation parameters: 35% relative efficiency, working voltage 4400 V and a DigiDart spectrometric chain. The spectra were acquired on 16384 channels in the energy field between 40 and 2610 keV, thus, a channel corresponds to approximately 0.16 keV. The experimental measurement data are analysed using the Gamma Vision-32 software, on samples of unprocessed salt of an approximate mass of 100 g. The Table 4 presents the main radionuclides with their spectral lines, with the differences between the activity of the sample and that of the background. Table 4 illustrates the total activity of the natural radionuclides (232Th, 235U, and 238U) in the salt rock and soil collected at different points of the Cacica salt mine. The activity of 232Th is comparatively higher than that of both 235U and 238U in all salt rock and soil samples. These results are comparable to

9 Natural therapeutic factors assessment for the use in speleotherapeutic Article no. 801 worldwide average concentration of these radionuclides in soils (UNSCEAR 2000) [22, 23], which are 30 Bq/kg for 232Th and 238U. We notice that the radionuclide activity in salt rock from the Cacica salt mine is much smaller than that of soil samples measured in 50 other locations in Romania (considered as reference), for parents and daughter of the uranium, thorium series. Such low radioactivity concentrations support very strongly the development of speleotherapy in the Cacica salt mine. It has been observed an increase in the value of the activity as the energy of the peak increases. This is due to the differences in density between the sample and the standard source with which the calibration was done, which causes an increase absorption in the sample at the lower energy and leads to an activity dependent evaluation to the energy of the analysed peak. The decrease of the calculated activity, for the same energies of the background and the sample, almost completely eliminates this discrepancy. From the analyses, it is observed that the weighted average gives smaller errors than the direct mediation.

Table 4 Activity concentrations of radionuclides in salt rock and soil from Cacica salt mine Salt rock RADIONUCLIDES Activity Uncertainty [Bq/kg] 40K < MDA 7Be < MDA 208Tl 3.31 0.25 212Pb < MDA 214Pb < MDA 212Bi 15.15 3.46 214Bi < MDA 226Ra 11.82 2.73 228Ac < MDA 228Th < MDA 234Th < MDA 235U < MDA 224Ra < MDA 223Ra 2.75 1.08 TOTAL ACTIVITY 33.03 9.13 232Th (Thorium series) 18.46 2.12 235U (Actinium series) 2.75 0.12 238U (Uranium series) 11.82 2.41 MDA = Minimum Detectable Activity

3.3. MEASURING THE CONCENTRATION OF AEROIONS

The concentration of aero-ions in the underground environment from the Cacica salt mine is different in the underground galleries and varies between

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1000 ÷ 1714 (total number ions/cm3) in the chosen locations, the unipolarity coefficient is predominantly subunit (on average, k = 0.98), indicating a slight predominance of small positive ions, including in average for the entire salt mine, which is a potentially positive fact for speleotherapy. Previous studies found ion concentrations for both polarities being on average 1306 total number ions/cm3 in the Gym Hall of investigated the Cacica salt mine.

3.4. MEASUREMENT OF AEROSOL DISPERSION

The aerosol was sedimented by the gravitational method in Petri dishes specially prepared for such studies. The aerosol samples were taken at different locations at the level of 30 cm from the saline soil (airway level of the patient lying in bed), at 70 cm (airway level of the patient during the sitting) and at 1.50 cm (airway level of the patient walking in the underground galleries) [24]. The size of the saline aerosol particles was measured using the NICON (Japan) type two- dimensional laser confocal microscope. The dispersion of the salt aerosol from the Cacica salt mine designated for the study differs in the galleries Dance Hall and Gym Hall, and especially in galleries 1, 2, 3 and 4 of the newly designed complex for speleotherapy and balneo- climatic tourism, being predominantly from particles of 1–5 μm, with the possibility of deposition in small bronchi.

Fig. 6 – Distribution of the concentration aerosol particles in Dance Hall, Cacica salt mine.

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Fig. 7 – Distribution of the concentration aerosol particles in Gym Hall, Cacica salt mine.

Fig. 8 – Distribution of the concentration aerosol particles near underground Salt Lake, Cacica salt mine.

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The results of the study carried out for aerosol dispersion are shown in the Figs. 6, 7 and 8. It is worth noting that in the Cacica salt mine galleries the aerosol is composed predominantly of particles with the size of up to 5 μm at different levels from the saline soil. The highest concentration of saline particles up to 2 μm was found at the level 1.50 m from the salt soil that is to the airway of patients walk in the underground galleries, and made up 82% in the Dance Hall. The concentration of salt aerosol particles of the size 1–2 μm did not significantly change near the salt lake, showing even a tendency to decrease compared to the data in the Dance Hall. In the gym, at the same level from the salt soil, the concentration of particles of 1–2 μm made up 49%. It is interesting the dispersion of saline aerosol composed of particles larger than 5 μm at different levels from the saline soil. It should be mentioned that with the decrease of the level from the saline soil, the concentration of particles up to 5 μm decreases and particles of the size 10–30 μm appear (Figs. 6, 7 and 8).

3.5. MEASURING THE CONCENTRATION OF MICROORGANISMS IN THE SALINE UNDERGROUND AIR

For the collection of air samples, the sedimentation method was used in Petri dishes with different culture media. As culture mediums the following were used: simple agarose, sheep-blood agarose, Sabourand agarose, hyper-chlorinated agarose, Glass Environment, AABTL Environment and other specific culture media. The identification of microorganisms was performed according to the morphology of colonies and microorganisms, the tinting properties (Gram coloration) and the use of specific media. The concentration of microorganisms in the underground air from the saline (near the salt lake, in the Dance Hall and the Gym Hall varies between (190–1260)/m3 air, with the tendency of higher concentrations in the Sports Hall. The lowest concentration of micro-organisms was found at level 1.50 m from the saline ground. The data indicate a lower concentration of microorganisms in the air of the investigated galleries from the salt mine.

3.6. MEASURING THE CONCENTRATION OF DIFFERENT GASES IN THE UNDERGROUND SALINE ENVIRONMENT

By the method of Gas Detection Tubes (RAE Systems Inc., USA and LP-1200 Hand Pump, 10 types of gases were investigated, finding a slightly increased concentration of carbon dioxide (0.068%) with the tendency to normalize after the ventilation of the mine. No toxic gases were detected, although there is a slight accumulation of hydrocarbons (15.95–18.3 ppm per volum), which after ventilation decreases to trace values (12.9 ppm per volum).

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4. CONCLUSIONS

The values obtained in the analysed locations show that is a very clean environment with limited contact with surface air. All samples of salt, air, and water analysed from the Cacica salt mine do not pose a radioactive hazard. The values of radon concentrations decrease quite a lot when the ventilation is functional, in relation to the non-aeration situation. In order to innovate the use of potentially therapeutic environmental factors in salt mines, in health and spa tourism, it can be said that they represent in terms of radioactivity special characteristics that can be used for speleotherapeutic purposes and spa tourism. The concentration and dispersion of saline aerosol inside the salt mine represents a therapeutic factor in treatment, especially for patients with chronic respiratory, inflammatory, and allergic diseases. The radiometric characterization of the saline environment, associated with complex medical-biological, clinical- functional studies, cellular immunology, cell biology, biochemistry, ionization, concentration, and dispersion of saline aerosol, the concentration of microorganisms, concentration of various gases in the saline underground environment, etc. represents a complementary alternative in speleotherapeutic treatment in the environment of salt mines. The results of the proposed analysis method have a positive impact on the development of new research directions such as: the decrease the use of expensive drug treatments, the decrease of frequency and duration of hospitalization, the increase of patients’ quality of life, the increase of the possibility of employment and rehabilitation in professional and social activity.

Acknowledgments. This research was supported by the Romanian Ministry for Education and Research, by Project No. 2550, FC 42120, in National Plan for RDI-2, Partnerships program, priority areas – Health, with the title Complex of medical-biological study of potential therapeutic factors related to salt mines and karst environments for effective use in health and balneo-turism; development and modelling solutions of these factors.

REFERENCES

1. L. Aniţei, M. Cristescu, E. Teodoreanu, L. Andriescu, V. Tihon, L. Buicliu, Studium der therapeutischen wirksamkeit des mikroklimas der salzgrube Tg. Ocna bei unspezifischen chronischen respiratorischen Erkrankungen, Zeitchr. Physiother, Leipzig 39 (1987). 2. S.P. Beamon, A. Falkenbach, G. Fainburg, K. Linde, Speleotherapy for asthma, Cochrane review. From the cochrane library, Is. 3, CD001741, Review (2001). 3. J. Chonka, J. Simionka, N. Sokolov, V. Gorbacev, I. Pop, K. Chonka, The state of external respiration and acid-base equilibrium of blood serum of children with bronchial asthma undergoing speleotherapy. Allergie & Immunologie, European Annals of Allergy and Clinical Immunology. Annual meeting Interasma 98, Prague, S. 2–12, suppl. en. n. 5, pp. 9–14 (1998). 4. V.P. Gorbenko, M.D. Torochtin, N.E. Povstianoy, I.S. Lemko, J.M. Somionka, P.P. Gorbenko, Influence of the aseptic microclimate of salt mines on curing burns (in Russian), International Congres of Speleology 10, Proceedings-communications, II, Budapest, Hungary, P. 411–417 (1998).

Article no. 801 Marian Romeo Calin et al. 14

5. S. Dluholucky, V. Rajcanova, Speleotherapy in the treatment of allergic respiratory tract is disorders – what is myth, what fact, Permanente Commission de Speleotherapie UIS UNESCO, International Symposium of Speleotherapy, 19–25, Solotvino, Ukraine, 1998. 6. I. Simionca, M. Hoteteu, A. Buturuga, L. Enache, D. Cinteza, I. Kiss, N. Grudnicki, N. Ursaciuc et al., Studii în vederea utilizării eficiente în medicină a unor saline din România cu proprietăţi terapeutice (speleoterapia), INRMFB 84, Bucharest, 54 (2004). 7. H. Lazarescu, I. Simionca, M. Hoteteu, L. Mirescu, Speleotherapy – modern bio-medical perspectives, Jour. Medicine & Life 7, 2, 247–252 (2014). 8. G. Maiorescu, V. Timotin, I. Simionca, N. Grudnicki, C. Zup, Existing and perspective arrangements to Salina Cacica in the context of tourism development in salt mines, Balneo Research Jour. 5, 1 (2014). 9. I. Simionca, Speleotherapy development in Romania on the world context and perspectives for use of some salt mines and karst caves for speleotherapeutic and balneoclimatic tourism purposes, Balneo Res. Jour., Vol. 4, 2, 133–139 (2013). 10. E. Teodoreanu, L. Enache, L. Aniţei, I. Simionca, Salines in Romania–climatic and therapeutical potential, Rev. Roum. Geografie, 16, 43–44, 165–174 (2000). 11. M.R. Calin, M. Zoran, M.A. Calin, Radon levels assessment in some Northern Romanian salt mines, J. Radioanal. and Nucl. Chem. 293, 2, 565–572 (2012). 12. M.R. Calin, M.A. Calin, Ghe. I. Simionca, I. Radulescu, O. Mera, Measurements of Radon concentration in salt mines for speleo-therapeutic treatment and balneo-turism, National Congress of Balneology, Baile Govora, Romania, 2017. 13. M.R. Calin, C.A. Simion, Ghe. I. Simionca, M.A. Calin, A.E. Druker, The characterization of the radioactivity in the Cacica salt mine, Rom. Rep. Phys. 63, 483–502 (2011). 14. M.R. Calin, M.A.Calin, Investigations on the presence and distribution of Radon in the Cacica salt mine, Romania, J. Radioanal. and Nucl. Chem. 288, 1, 203–206 (2011). 15. M.R. Calin, M.A. Calin, L. Done, et al., Assessment of calibration parameters for gamma-ray spectrometry systems, J. Radioanal. and Nucl. Chem. 288, 2, 547–552 (2011). 16. M.R. Calin, M.A. Calin, System for air 222Rn activity concentration measurements based on ion-pulse ionization chamber detector, J. Radioanal. and Nucl. Chem. 288, 1, 109–114 (2011). 17. M.R. Calin, M.A. Calin, Evaluation of the radon concentration in Ocna Dej salt mine, Romania, J. Radioanal. and Nucl. Chem. 286, 1, 169–173 (2010). 18. B.T. Obreja, E. Neacsu, L. Done, F. Dragolici, L. Tugulan, L. Zicman, D.Scradeanu, Evaluation of environmental monitoring data at low and intermediate – level radioactive waste repository Baita (Bihor), Romania, Rom. J. Phys. 61, 3–4, 718–727 (2016). 19. L. Tugulan, F.M. Dragolici, G. Chirosca, A.V. Chirosca, O.G. Duliu, Radiation exposure in underground low activity radioactive waste repository, Rom. J. Phys. 60, 9–10, 1598–1605 (2015). 20. M. Dolha, A. Timar-Gabor, T. Dicu, C. Cosma, Measurements of terrestrial gamma dose rates and radon concentrations from indoor air and water in region, Rom. Rep. Phys. 69, 701 (2017). 21. M.G. Erdoğan, B. Akkuş, L. Amon Susam, N. Hafizoğlu Alkan, A. Ertoprak., Y. Öktem, F.Ç. Öztürk, Radon concentrations and gamma radiation activity measurements of Muğla, Turkey, Rom. Rep. Phys. 71, 717 (2019). 22. UNSCEAR 2000 Report Sources and effects of ionizing radiation, Report to the general assembly with scientific annexes, United Nations, New York. 23. UNSCEAR 2006, Sources and effects of ionizing radiation, Report to the general assembly with scientific annexes, New York. 24. A. Wiszniewski, Environment of Air-Ions in Healing Chambers in the Wieliczka Salt Mine, Acta Phys. Polonica A 127, 1661–1665 (2015).