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Urine, hair and nail samples were collected from a population of both sex aged from 40 to 87 years in Niška Banja (227 km south of Belgrade, Serbia) with a high level of natural radioactivity (HLNRA). To assess and monitor the public exposure, urine samples for each subject (24 h period) were collected and concentration of uranium (U) was analysed using alpha-particle spectrometry. Human hair and nails considered as bio-indicators of the public exposure to radionuclides over a long period of months or even years and concentration of U was determined using inductively coupled plasma-mass spectrometry. The mean concentrations of U in urine, hair and nail were 123 ng/L, 17 ng/g and 8 ng/g, respectively. There was a large variation and may be due to geological origin.

The requirements about radon measurements in schools and public buildings included in most of the national and international legislations are generally restricted to all the rooms located at the ground floor and basement, assuming the soil beneath the building as the main source of indoor radon. In order to verify such an assumption for small buildings having at maximum two floors, a preliminary study was performed in 50 schools located in 15 municipalities of the Republic of Srpska. Results of this study suggest that a protocol requiring measurements at the ground floor only may be considered adequate. Due to the high radon spatial variability for rooms at the ground floor, it is preferable to require measurements in a high number of rooms (preferably in all of them) in order to assess the compliance with the reference level established by the legislation.

The long–term measurements of radon and thoron equilibrium equivalent concentrations (EERC and EETC) were carried out the first time in Republic of Srpska in 25 schools of its capital Banja Luka and in its wider surroundings. After this successful survey, the measurements continued using the same type of the LR 115 nuclear track detectors, i.e., Direct Radon Progeny Sensors/Direct Thoron Progeny Sensors (DRPS/DTPS), and they were deployed in the 36 dwellings nearby the investigated schools. The detectors were exposed for one year period at 15–20 cm distance from the walls. The EERC and EETC were found to vary in the range from 6.3 to 14.4 Bq/m3and from 0.10 to 1.1 Bq/m3, with geometric mean 9.3 and 0.36, respectively. The same variance of EER and EET concentrations, measured in living and bedrooms of buildings built with different construction materials as well at different floors have been obtained. The insignificant correlations between EERC and EETC, show that these concentrations appeared to be independent in investigated dwellings. The calculated ratio of EETC to EERC ranged from 0.01 to 0.16 with the geometric mean of 0.04. The aim of this study is to give possible scientific contribution considering the explanation of EERC and EETC behavior in an indoor environment.

Radon (222Rn) and thoron (220Rn) are natural radioactive gases, generated in the terrestrial materials. They are the main sources of public exposure to ionising radiation in any of indoor environment worldwide. Differences in half-lives of 222Rn (T1/2 = 3.8 d) and 220Rn (T1/2 = 55.6 s) lead to its different indoor behavior. Several studies of indoor 222Rn and 220Rn in Northern Macedonia have been performed, starting with measurements in dwellings in 2008 and continuing with measurements in schools during 2012. The surveys in the Republic of Srpska began later (in 2011) with the simultaneous 222Rn and 220Rn measurements in the dwellings and schools of Banja Luka cities. This paper, as a result of our cooperation, summarizes the results and general conclusions obtained from 222Rn and 220Rn measurements in schools of capitals. In both cities, the measurements were made using Raduet - nuclear track detectors; deployed at distances: >0.5m (Skopje) and 0.2m (Banja Luka); and exposed in a period: March 2012 - May 2012 (Skopje) and April 2011 - May 2012 (Banja Luka). Results for 222Rn and 220Rn concentrations in both cities have a log-normal distribution. The 222Rn geometric mean value of 71 Bq/m3 in Skopje is higher than in Banja Luka city (GM = 50 Bq/m3). Among different radon potential in the cities, this difference could be related to the different exposure time of detectors. Furthermore, the dispersion of the 222Rn results in each city expressed through geometric standard deviation is relatively low: GSD = 2.13 (Skopje) and GSD = 2.11 (Banja Luka) indicating relatively homogeneous data sets. The 220Rn concentrations in Banja Luka (GM = 51 Bq/m3) were higher than in Skopje (GM = 11 Bq/m3). It is obvious that in the case of 220Rn, the exposure period did not play a significant role. One of the reasons for this difference could be the position of the detectors as well as the different building materials in the schools. On the contrary, the dispersion of the 220Rn results in Skopje (GSD = 3.38) was greater than in Banja Luka (GSD = 2.07).Keywords: radon, thoron, gas, school.

The most abundant and efficient source of air ionization in the lower layer of the atmosphere is radon. As an alpha emitter, radon plays a crucial role in the earth's atmospheric electricity. Besides the physical, radon and ions have a significant biological role concerning human health: radon is a health hazard while the ions are beneficial ingredients of the air we breathe. In this study, we examined the dynamics of radon and air ions diurnal change in houses with different floor and windows insulations. Measurements were made using continual radon monitor Rad-7 and air ion counter CDI-06. Diurnal and spatial variations of both atmospheric constituents are mutually related and dependent mostly on radon exhalation potential, meteorological parameters, aerosol concentration and formation of the temperature inversion layer. Indoor concentrations are related to the potential for accumulation of radon that is coming from the ground beneath the foundation and also influenced by external radon concentration that is diffusing through the walls, doors, and windows. Level of diffusion is depending on insulation. The difference in the paths by which radon enters the home can be seen by analyzing changes during diurnal continuous measurements.Keywords: radon, air ions, ionization, atmosphere, air, natural radioactivity.

The most abundant and efficient source of air ionization in the lower layer of the atmosphere is radon. As an alpha emitter, radon plays cruciant role in the earth atmospheric electricity. Besides physical, radon and ions have a significant biological role concerning human health: radon is health hazard while the ions are beneficial ingredient of the air we breathe. Measurements were made using continual radon monitor Rad-7 and air ion counter CDI-06. Diurnal and spa¬tial variations of both atmospheric constitutens are mutually related and dependant mo¬stly on radon exhalation potential, meterological parameters, aerosol con¬cen-tra¬ti¬on and formation of temperature inversion layer. Indoor concentrations are re¬la¬ted to radon accumulation and partiallz influenced by external radon concentration

The long-term measurements of radon and thoron equilibrium equivalent concentrations (EERC and EETC) were carried out the first time in Republika Srpska in 25 schools of its capital Banja Luka and in its wider surroundings. After this successful survey the measurements continued using the same type of the LR115 nuclear track detectors, i.e., Direct Radon Progeny Sensors/Direct Thoron Progeny Sensors (DRPS/DTPS), which were deployed in the 36 dwellings nearby the investigated schools. The aim of this study was to give possible scientific contribution considering an explanation of EERC and EETC behavior in indoor environment. The detectors were exposed for one year period at 15–20 cm distance from the walls. The EERC and EETC were found to vary in the range from 6.3 to 14.4 Bqm−3 and from 0.10 to 1.1 Bqm−3, with geometric mean 9.3 and 0.36, respectively. The same variance of EER and EET concentrations, measured in living and bedrooms of buildings built with different construction materials as well at different floors, have been obtained. The insignificant corre¬lations between EERC and EETC, shows that these concentrations appeared to be independent in investigated dwellings. The calculated ratio of EETC to EERC ranged from 0.01 to 0.16 with the geometric mean of 0.04.

Radon (222Rn) and thoron (220Rn) are natural radioactive gases, generated in the terrestrial materials. They are the main sources of public exposure to ionising radiation in indoor environment worldwide. Differences in half-lives of 222Rn (T1/2=3.8 d) and 220Rn (T1/2=55.6 s) lead to its different indoor behavior. Se¬ve¬ral studies of indoor 222Rn and 220Rn in Northern Macedonia have been per¬for¬med, starting with measurements in dwellings in 2008 and continuing with mea¬su¬re-ments in schools during 2012. The surveys in the Republic of Srpska began later (in 2011) with the simultaneous 222Rn and 220Rn measurements in the dwellings and schools of Banja Luka cities. This paper, as a result of our coop¬eration, su¬m-ma¬rizes the results and general conclusions obtained from 222Rn and 220Rn mea¬su-re¬ments in schools of capitals. In both cities, the measurements were made using Raduet - nuclear tracer detectors; deployed at distances: >0.5m (Skopje) and 0.2m (Banja Luka); and exposed in a period: March 2012 - May 2012 (Skopje) and April 2011 -May, 2012 (Banja Luka). Results for 222Rn and 220Rn concentrations in both cities have a log-normal distribution. The 222Rn geometric mean value of 71 Bq/m3 in Skopje are higher than in Banja Luka city (GM = 50 Bq/m3). Among other factors that affect 222Rn variations, this difference could be related to the different exposure time of detectors. Furthermore, the dispersion of the 222Rn results in each city expressed through geometric standard deviation is relatively low: GSD = 2.13 (Skopje) and GSD = 2.11 (Banja Luka) indicating re¬la¬ti-vely homogeneous data sets. The 220Rn concentrations in Banja Luka (GM = 51 Bq/m3) were higher than in Skopje (GM = 11 Bq/m3). It is obvious that in the case of 220Rn, the exposure pe¬ri¬od did not play a significant role. One of the reasons for this difference could be the position of the detectors as well as the different buil-ding materials in the sch¬o¬ols. On contrary, the dispersion of the 220Rn results in Skop¬je (GSD = 3.38) was greater than in Banja Luka (GSD = 2.07).

The main contribution to population exposure is due to radon and thoron progenies and not radon itself. The aim of this study was therefore to estimate annual effective dose using the results of Direct Radon and Thoron Progeny Sensors were exposed in 69 selected schools and 319 dwellings in several regions of Balkans: in Serbia: regions of Sokobanja and Kosovo and Metohija, Republic of Macedonia, Republic of Srpska and Slovenia. Obtained average total effective doses are in the range from 0.22 mSv a-1 (schools in Republic of Srpska) to 2.5 mSv a-1 (dwellings in Kosovo) and are below the reference level of 10 mSv a-1 recommended by International Commission on Radiological Protection. © The Author(s) 2019. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

In the last decade, many studies have been made for measuring natural radioactivity in regions of the Republic of Macedonia. However, the information on terrestrial radiation exposure, and, consequently, risk assessment were not available. In this study, a risk assessment was done considering a specific activity concentration of 137 Cs in the topsoil. The results indicate that the external gamma doses due to natural radionuclides in soils are higher than those of 137 Cs. The absorbed dose rate in air varies in intervals: from 4.3 to 57 nGy/h (due to Ra); from 3.9 to 88 nGy/h (due to 232 Th); from 3.3 to 58 nGy/h (due to 40 K); and from 0.01 to 5.3 nGy/h (due to Cs). In addition, the mean annual effective doses due to natural radionuclides and 137 Cs in the soils of the Republic of Macedonia are estimated to be 78 μSv and 1.01 μSv, respectively. As well as, the values of external hazard index H ex indicate in general low gamma radiation risk for populations living in the Republic of Macedonia. 226 226 137 Ra, 232 Th, 40 K and

To establish baseline values of concentrations of terrestrial radionuclides for the Republic of Macedonia, a survey covering the entire territory was performed. 213 soil samples were collected from regions around the major settlements and cities, about evenly distributed over the geotectonic units which constitute the country’s geological foundation. The specific activities of radionuclides were measured by gamma spectrometry. The values were in ranges: (8-1390) Bq kg-1 for 40K, (9-123) Bq kg-1 for 226Ra, (9-111) Bq kg-1 for 238U and (7-145) Bq kg-1 for 232Th in dry soil. The relation between specific activities of natural radionuclides and geology was investigated. Correlation between radionuclides, which may serve as additional geochemical indicators, and geology could not be found convincingly. Mutual correlations between 226Ra, 238U and 232Th activities were found to be high (Spearman  about 0.8), whereas the ones between these and 40K are a bit lower, somewhat above =0.6.

The paper deals with the analysis of the annual indoor radon concentrations variations due to different geological parameters of Sjenica community, Western Serbia. The measured 222Rn concentrations were ranging from 10 to 1130 Bq/m3. In 14% of the buildings, the radon action level of 300 Bq/m3 is exceeded, indicating that Sjenica community could be characterized as a radon priority area. Each of 35 measuring location was georeferenced and corresponding lithostratigraphic units and geological period was assigned. Data were analyzed using the multiple linear regression (MLR) method and two predictive models were developed. The MLR model generated by the geological periods explained 17% of the radon variability while, the better one, was the lithostratigraphic MLR model, which explained 52% of the radon variability. Analysis has shown that lithostratigraphic units are important parameters in the prediction of radon levels. © 2019 Carpathian Journal of Earth and Environmental Sciences.

The main contribution to the population exposure is due to radon and thoron progenies and not radon and thoron itself. Nevertheless, due to the simplicity and cost effectiveness of radon/thoron measurements compared to the measurements of their progenies, effective doses are usually estimated from the measured Rn/Tn concentrations with the assumed value of equilibrium factor. In this paper, an overview of direct measurements of radon and thoron progenies is some parts of Balkans performed within the framework of large international collaboration is given. In this joint venture, long-term measurements were carried out in dwellings and schools using direct radon progeny sensors/direct thoron progeny sensors (DRPSs/DTPSs). Large scale Rn/Tn progeny survey was performed using 321 DRPSs/DTPSs detectors in the period from 2011 till 2013 encompassing some parts of Serbia: 125 dwellings in the region of Soko Banja (Southern Serbia), 48 dwellings in Kosovo, 44 schools in FYR of Macedonia and 37 dwelling and 25 schools in Republic of Srpska. The detectors were deployed from 3 months up to one year, since long term measurements are essential for assessing inhalation doses to the public. In case where possible seasonal variations were discussed as well. Effective doses were estimated from measured equilibrium equivalent radon and thoron concentrations (EERC and EETC) considering different occupancy factors for inhabitants and pupils.

Radon is a natural radioactive gas present in each indoor environment. Its harmful health effect is confirmed in many epidemiological studies. In the Republic of Macedonia, since 2008 intensive survey of radon measurements in dwellings have been started and continued with measurements in schools in 2012. Survey of indoor radon concentration in dwellings and schools of Republic of Srpska started in 2011, in Banja Luka city. In this paper, we present only the results of measurements performed in primary schools of Skopje and Banja Luka cities. In both cities, the radon measurements were performed with different types of detectors, but for this paper, the only measurements by the Raduet detector were used. Comparing the 222Rn results it can be concluded: Arithmetic means are higher than geometric mean values indicating log normal distributions; The values in Skopje are higher than in Banja Luka city. Considering a number of factors that affect radon variations, there are many reasons for differences. One of them is the different exposure time of the detectors. On the other hand, the dispersion of the results in each city expressed through the geometric standard deviation is relatively low indicating relatively homogeneous factors. Comparing the 220Rn it can be concluded: Arithmetic means are higher than geometric mean values indicating log normal distributions; The values in Banja Luka are higher than in Skopje. It is obvious that in the case of 220Rn, the exposure period does not play a significant role. One of the reasons for this difference could be the position of the detectors as well as different building materials in the schools. The dispersion of the results in Skopje is greater than in Banja Luka.

Quantification of uranium in human urine is a valuable technique for assessing occupant and public exposure to uranium. Human hair and nails can be considered as bio-indicators of the public exposure to certain natural radionuclides and other toxic metals over a long period of months or even years.All urine, hair and nail samples were collected from a population of both sex aged from 40 to 87 years in Niška Banja (227 km south of Belgrade) with a high level of natural radioactivity (HLNRA), a suburban municipality, of Serbia which located in the quaternary alluvium of River Nišava along the contact of the Koritnik limestone and travertine rock. Air dose rate in indoor environment has been measured. To assess and monitor the public exposure, urine, hair and nail samples were collected to analyze the concentration of uranium, using inductively coupled plasma mass spectrometry and alpha-particle spectrometry. Uranium was determined in 24 h samples. After addition of radioactive tracer U-232 and concentrated nitric acid, samples were evaporated to dryness. Residues were wet ashed with nitric acid and H2O2, radiochemical separation of uranium radioisotopes were performed by extraction chromatography using UTEVA resin.Source preparation for alpha-particle spectrometry was carried out by the micro-coprecipitation method with neodymium fluoride.U concentrations in hair, nail and urine varied from 0.2 to 77.1 ppb, 2.5 to 44.7 ppb, 54-730 ppb respectively.There was a large variation and may be due to geological origin and anthropogenic activities.