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Dicu T, Cucoş A, Botoş M, Burghele B, Florică Ş, Baciu C, Ştefan B, Bălc R. Exploring statistical and machine learning techniques to identify factors influencing indoor radon concentration. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 905:167024. [PMID: 37709073 DOI: 10.1016/j.scitotenv.2023.167024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 09/10/2023] [Indexed: 09/16/2023]
Abstract
Radon is a radioactive gas with a carcinogenic effect. The malign effect on human health is, however, mostly influenced by the level of exposure. Dangerous exposure occurs predominantly indoors where the level of indoor radon concentration (IRC) is, in its turn, influenced by several factors. The current study aims to investigate the combined effects of geology, pedology, and house characteristics on the IRC based on 3132 passive radon measurements conducted in Romania. Several techniques for evaluating the impact of predictors on the dependent variable were used, from univariate statistics to artificial neural network and random forest regressor (RFR). The RFR model outperformed the other investigated models in terms of R2 (0.14) and RMSE (0.83) for the radon concentration, as a dependent continuous variable. Using IRC discretized into two classes, based on the median (115 Bq/m3), an AUC-ROC value of 0.61 was obtained for logistic regression and 0.62 for the random forest classifier. The presence of cellar beneath the investigated room, the construction period, the height above the sea level or the floor type are the main predictors determined by the models used.
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Affiliation(s)
- T Dicu
- "Constantin Cosma" Radon Laboratory (LiRaCC), Faculty of Environmental Science and Engineering, "Babeş-Bolyai" University, Fântânele Street, no. 30, Cluj-Napoca, Romania
| | - A Cucoş
- "Constantin Cosma" Radon Laboratory (LiRaCC), Faculty of Environmental Science and Engineering, "Babeş-Bolyai" University, Fântânele Street, no. 30, Cluj-Napoca, Romania.
| | - M Botoş
- Faculty of Civil Engineering, Technical University of Cluj-Napoca, C. Daicoviciu Street, no. 15, Cluj-Napoca, Romania
| | - B Burghele
- SC Radon Action SRL, Str. Mărginaşă 51, 400371 Cluj-Napoca, Romania
| | - Ş Florică
- "Constantin Cosma" Radon Laboratory (LiRaCC), Faculty of Environmental Science and Engineering, "Babeş-Bolyai" University, Fântânele Street, no. 30, Cluj-Napoca, Romania
| | - C Baciu
- "Constantin Cosma" Radon Laboratory (LiRaCC), Faculty of Environmental Science and Engineering, "Babeş-Bolyai" University, Fântânele Street, no. 30, Cluj-Napoca, Romania
| | - B Ştefan
- "Constantin Cosma" Radon Laboratory (LiRaCC), Faculty of Environmental Science and Engineering, "Babeş-Bolyai" University, Fântânele Street, no. 30, Cluj-Napoca, Romania
| | - R Bălc
- "Constantin Cosma" Radon Laboratory (LiRaCC), Faculty of Environmental Science and Engineering, "Babeş-Bolyai" University, Fântânele Street, no. 30, Cluj-Napoca, Romania
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Abbasi A, Algethami M, Bawazeer O, Zakaly HMH. WINDCATCHER VENTILATION COMPUTATION AND INDOOR 222RN CONCENTRATION IN TRADITIONAL ADOBE HOUSES. RADIATION PROTECTION DOSIMETRY 2021; 197:175-182. [PMID: 34959244 DOI: 10.1093/rpd/ncab178] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 09/13/2021] [Accepted: 11/28/2021] [Indexed: 06/14/2023]
Abstract
Radon-based radiation is a significant issue that can affect resident health as a contributory source of natural radiation from soil construction materials. This study investigates the effect of windcatchers on radon activity concentrations and radon exhalation rate from the soil surface in traditional adobe houses of Yazd, Iran. Radon concentrations were measured by passive detectors in 16 adobe houses. Computational fluid dynamics simulations were performed for different wind speed to calculate ventilation rate. The concentrations of 222Rn were in the ranges of 22 ± 1-117 ± 8 Bq m-3 with an average value of 50 ± 3 Bq m-3. The radon exhalation rates values were in the range of 8.3 ± 0.1 to 47.2 ± 0.5 Bq m-2 h-1. Radon concentration results in only one dwelling site were higher than the level recommended by the World Health Organization. The annual radon inhalation dose was found in seven sites higher than the worldwide average.
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A study on indoor radon, thoron and their progeny level in Mokokchung district of Nagaland, India. J Radioanal Nucl Chem 2021. [DOI: 10.1007/s10967-021-08096-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Indoor radon levels in Hungarian kindergartens. J Radioanal Nucl Chem 2021. [DOI: 10.1007/s10967-020-07501-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
AbstractAnnual average indoor radon activity concentration was studied in 88 Hungarian kindergartens in 76 towns of 10 different counties. Annual average indoor radon activity concentration in the kindergartens was 61 Bq m− 3, maximum was 160 Bq m− 3. In the kindergartens the seasonal variation of radon is not so strong like in dwellings, because of the permanent ventilation and the closed period during the summer break.
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Richter M, Horn W, Juritsch E, Klinge A, Radeljic L, Jann O. Natural Building Materials for Interior Fitting and Refurbishment-What about Indoor Emissions? MATERIALS 2021; 14:ma14010234. [PMID: 33466502 PMCID: PMC7796468 DOI: 10.3390/ma14010234] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 12/18/2020] [Accepted: 12/28/2020] [Indexed: 11/16/2022]
Abstract
Indoor air quality can be adversely affected by emissions from building materials, consequently having a negative impact on human health and well-being. In this study, more than 30 natural building materials (earth dry boards and plasters, bio-based insulation materials, and boards made of wood, flax, reed, straw, etc.) used for interior works were investigated as to their emissions of (semi-)volatile organic compounds ((S)VOC), formaldehyde, and radon. The study focused on the emissions from complete wall build-ups as they can be used for internal partition walls and the internal insulation of external walls. Test chambers were designed, allowing the compounds to release only from the surface of the material facing indoors under testing parameters that were chosen to simulate model room conditions. The emission test results were evaluated using the AgBB evaluation scheme, a procedure for the health-related evaluation of construction products and currently applied for the approval of specific groups of building materials in Germany. Seventeen out of 19 sample build-ups tested in this study would have passed this scheme since they generally proved to be low-emitting and although the combined emissions of multiple materials were tested, 50% of the measurements could be terminated before half of the total testing time.
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Affiliation(s)
- Matthias Richter
- Materials and Air Pollutants Division, Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 44-46, 12203 Berlin, Germany; (W.H.); (E.J.); (O.J.)
- Correspondence: (M.R.); (A.K.)
| | - Wolfgang Horn
- Materials and Air Pollutants Division, Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 44-46, 12203 Berlin, Germany; (W.H.); (E.J.); (O.J.)
| | - Elevtheria Juritsch
- Materials and Air Pollutants Division, Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 44-46, 12203 Berlin, Germany; (W.H.); (E.J.); (O.J.)
| | - Andrea Klinge
- ZRS Architekten Ingenieure, Schlesische Straße 26, 10997 Berlin, Germany;
- Correspondence: (M.R.); (A.K.)
| | - Leon Radeljic
- ZRS Architekten Ingenieure, Schlesische Straße 26, 10997 Berlin, Germany;
| | - Oliver Jann
- Materials and Air Pollutants Division, Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 44-46, 12203 Berlin, Germany; (W.H.); (E.J.); (O.J.)
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Nguyễn-Văn H, Nguyễn-Thùy D, Nguyễn NTÁ, Streil T, Schimmelmann JP, Doiron KE, Nguyễn-Đình T, Nguyễn-Thị H, Schimmelmann A. Excessive radon-based radiation in indoor air caused by soil building materials in traditional homes on Đồng Văn karst plateau, northern Vietnam. CHEMOSPHERE 2020; 257:127119. [PMID: 32497835 DOI: 10.1016/j.chemosphere.2020.127119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 05/07/2020] [Accepted: 05/15/2020] [Indexed: 05/22/2023]
Abstract
Radon-based radiation from natural soil building materials is an important factor likely influencing residents' health as a contributing source of natural radiation. This survey aims to quantify the nuclide-specific α-radiation of isotopes 222Rn and 220Rn in common types of houses in a region of northern Vietnam, Đồng Văn karst plateau, to preliminarily (i) evaluate the total annual effective dose rates and (ii) assess the relative risk of cancer induction from indoor α-radiation for inhabitants. The average 222Rn concentrations in all house types were lower than 100 Bq m-3, but 220Rn abundances were far higher than 222Rn, even up to >1000 Bq m-3 in air close to a wall of unfired-soil bricks. The estimated total annual effective dose rates from indoor 222Rn and 220Rn and their progenies to residents with daily exposure of 13 h in the various types of houses range from 3.1 to 4.3 mSv a-1 for houses constructed with modified materials, but up to higher than 6 mSv a-1 in houses with raw building materials. The average risk of developing lung cancer as a consequence of a lifetime exposure to indoor α-radiation in affected homes ranges from 3.9% to 14.6%. 220Rn and its metallic progenies contribute more than 80% of the total average lung cancer risk from total radon, being responsible for a range of 2.7-14.6% of the risk of developing lung cancer.
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Affiliation(s)
- Hướng Nguyễn-Văn
- Faculty of Geology, University of Science, Vietnam National University, Hanoi (VNU), 334 Nguyễn Trãi Street, Thanh Xuân District, Hanoi, Viet Nam; EOS Geoscience Research Group, Vietnam National University, Hanoi, Viet Nam.
| | - Dương Nguyễn-Thùy
- Faculty of Geology, University of Science, Vietnam National University, Hanoi (VNU), 334 Nguyễn Trãi Street, Thanh Xuân District, Hanoi, Viet Nam.
| | - Nguyệt Thị Ánh Nguyễn
- Faculty of Geology, University of Science, Vietnam National University, Hanoi (VNU), 334 Nguyễn Trãi Street, Thanh Xuân District, Hanoi, Viet Nam; EOS Geoscience Research Group, Vietnam National University, Hanoi, Viet Nam.
| | - Thomas Streil
- SARAD GmbH, Wiesbadener Str. 20, 01159, Dresden, Germany.
| | | | - Kelsey E Doiron
- Indiana University, Department of Earth and Atmospheric Sciences, 1001 East 10th Street, Bloomington, IN, 47405-1405, USA.
| | - Thái Nguyễn-Đình
- Faculty of Geology, University of Science, Vietnam National University, Hanoi (VNU), 334 Nguyễn Trãi Street, Thanh Xuân District, Hanoi, Viet Nam; EOS Geoscience Research Group, Vietnam National University, Hanoi, Viet Nam.
| | - Hồng Nguyễn-Thị
- Faculty of Geology, University of Science, Vietnam National University, Hanoi (VNU), 334 Nguyễn Trãi Street, Thanh Xuân District, Hanoi, Viet Nam; EOS Geoscience Research Group, Vietnam National University, Hanoi, Viet Nam.
| | - Arndt Schimmelmann
- Indiana University, Department of Earth and Atmospheric Sciences, 1001 East 10th Street, Bloomington, IN, 47405-1405, USA.
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Salupeto-Dembo J, Szabó-Krausz Z, Völgyesi P, Szabό C. Radon and thoron radiation exposure of the Angolan population living in adobe houses. J Radioanal Nucl Chem 2020. [DOI: 10.1007/s10967-020-07215-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
AbstractThis study investigates radon and thoron activity concentrations in adobe houses of Angola. Activity concentrations were recorded by passive detectors in rainy and dry seasons in 40 dwellings located at three areas with different climatic and geological backgrounds (Cabinda, Huambo, Menongue). Regarding seasonal and spatial variations, radon activity concentrations are higher in the rainy than in the dry season and both radon and thoron levels are the highest in Huambo, the central part of the country. The number of adobe houses above certain radon and thoron levels were estimated and the contribution of thoron to the inhalation dose was significant.
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Ivanova K, Stojanovska Z. Modelling of the temporal indoor radon variation in Bulgaria. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2019; 58:337-344. [PMID: 30955050 DOI: 10.1007/s00411-019-00789-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2018] [Accepted: 03/30/2019] [Indexed: 06/09/2023]
Abstract
In this study, temporal variations of indoor radon concentrations in Bulgaria were investigated. The radon concentrations were measured by nuclear track detectors as part of the Bulgarian National Survey, performed in the dwellings of 28 regional districts. The detectors were exposed through a year in two consecutive time periods of different lengths. For 2433 dwellings, measurements could be completed for both time periods, while for 345 dwellings they could only be completed for one of the periods. To estimate any missing radon concentrations, a temporal correction procedure was developed. This procedure, which included development of a linear correlation between the ln-transformed radon concentrations from the 9-month period [CRn(L)] and from the 3-month period [CRn(S)]. A normal distribution of the data, which is a condition for linear regression, was achieved when the ln-transformed radon concentrations were grouped by climate zone, then by regional districts, and finally by the presence/absence of a basement in the investigated building. The linear models obtained for each group showed reasonable coefficients of determination (R2 ≈ 0.50) and root mean square errors (RMSEs) of about 0.50. When these correlations were used to reconstruct radon concentrations in missing measurement periods, it turned out that the reconstructed data (for 345 dwellings) were within the 95% confidence interval of the measured data (for 2433 dwellings). The geometric means of CRn(L) and CRn(S) were 76 Bq/m3 and 100 Bq/m3, respectively, for 2433 dwellings, which are almost equal to those of 75 Bq/m3 and 98 Bq/m3, which represent the measured and reconstructed data together (for 2778 dwellings).
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Affiliation(s)
- Kremena Ivanova
- National Centre of Radiobiology and Radiation Protection, 3 Sv. Georgi Sofiyski St., 1606, Sofia, Bulgaria.
| | - Zdenka Stojanovska
- Faculty of Medical Sciences, Goce Delcev University of Stip, 10-A Krste Misirkov st, 2000, Stip, Republic of Macedonia
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Kaur M, Kumar A, Mehra R, Mishra R. Dose assessment from exposure to radon, thoron and their progeny concentrations in the dwellings of sub-mountainous region of Jammu & Kashmir, India. J Radioanal Nucl Chem 2017. [DOI: 10.1007/s10967-017-5632-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Meisenberg O, Mishra R, Joshi M, Gierl S, Rout R, Guo L, Agarwal T, Kanse S, Irlinger J, Sapra BK, Tschiersch J. Radon and thoron inhalation doses in dwellings with earthen architecture: Comparison of measurement methods. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017; 579:1855-1862. [PMID: 27939079 DOI: 10.1016/j.scitotenv.2016.11.170] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2016] [Revised: 11/04/2016] [Accepted: 11/24/2016] [Indexed: 06/06/2023]
Abstract
The radioactive noble gas radon (222Rn) and its decay products have been considered a health risk in the indoor environment for many years because of their contribution to the radiation dose of the lungs. The radioisotope thoron (220Rn) and its decay products came into focus of being a health risk only recently. The reason for this is its short half-life, so only building material can become a significant source for indoor thoron. In this study, dwellings with earthen architecture were investigated with different independent measurement techniques in order to determine appropriate methods for reliable dose assessment of the dwellers. While for radon dose assessment, radon gas measurement and the assumption of a common indoor equilibrium factor often are sufficient, thoron gas has proven to be an unreliable surrogate for a direct measurement of thoron decay products. Active/time-resolved but also passive/integrating measurements of the total concentration of thoron decay products demonstrated being precise and efficient methods for determining the exposure and inhalation dose from thoron and its decay products. Exhalation rate measurements are a useful method for a rough dose estimate only if the exhalation rate is homogeneous throughout the house. Before the construction of a building in-vitro exhalation rate measurements on the building material can yield information about the exposure that is to be expected. Determining the unattached fraction of radon decay products and even more of thoron decay products leads to only a slightly better precision; this confirms the relative unimportance of the unattached thoron decay products due to their low concentration. The results of this study thereby give advice on the proper measurement method in similar exposure situations.
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Affiliation(s)
- Oliver Meisenberg
- Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Radiation Protection, Ingolstädter Landstr. 1, 85764 Neuherberg, Germany.
| | - Rosaline Mishra
- Bhabha Atomic Research Centre, Radiological Physics and Advisory Division, Mumbai 400 085, India.
| | - Manish Joshi
- Bhabha Atomic Research Centre, Radiological Physics and Advisory Division, Mumbai 400 085, India
| | - Stefanie Gierl
- Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Radiation Protection, Ingolstädter Landstr. 1, 85764 Neuherberg, Germany
| | - Rajeswari Rout
- Bhabha Atomic Research Centre, Radiological Physics and Advisory Division, Mumbai 400 085, India
| | - Lu Guo
- Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Radiation Protection, Ingolstädter Landstr. 1, 85764 Neuherberg, Germany
| | - Tarun Agarwal
- Bhabha Atomic Research Centre, Radiological Physics and Advisory Division, Mumbai 400 085, India
| | - Sandeep Kanse
- Bhabha Atomic Research Centre, Radiological Physics and Advisory Division, Mumbai 400 085, India
| | - Josef Irlinger
- Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Radiation Protection, Ingolstädter Landstr. 1, 85764 Neuherberg, Germany
| | - Balvinder K Sapra
- Bhabha Atomic Research Centre, Radiological Physics and Advisory Division, Mumbai 400 085, India.
| | - Jochen Tschiersch
- Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Radiation Protection, Ingolstädter Landstr. 1, 85764 Neuherberg, Germany.
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El-Kameesy SU, Salama E, El-Fiki SA, Ehab M, Rühm W. Radiological safety assessment inside ancient Egyptian tombs in Saqqara. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2016; 52:567-576. [PMID: 26988604 DOI: 10.1080/10256016.2016.1142444] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2015] [Accepted: 11/10/2015] [Indexed: 06/05/2023]
Abstract
Many archaeological sites in Egypt are unique worldwide, such as ancient tombs and pyramids, because they document fundamental developments in human civilization that took place several thousands of years ago. For this reason, these sites are visited by numerous visitors every year. The present work is devoted to provide a pre-operational radiological baseline needed to quantify occupational radiation exposure at the famous Saqqara region in Cairo, Egypt. A hyperpure Ge detector has been used in the γ-ray spectrometric analysis while the (222)Rn concentration was measured using a portable radon monitor RTM 1688-2, SARAD. The mean specific activities of (226)Ra, (232)Th and (40)K in the samples collected from the interior walls of the Saqqara tombs were determined and found to show average values of 16, 8.5 and 45 Bq kg(-1), respectively. The concentration of radon was measured inside the tombs Serapeum, South tomb and the Zoser Pyramid (fifth level) and an associated average working level of 0.83 WL was obtained. In order to avoid the health hazards associated with the exposure to radon during the long period of work inside these tombs, proposed solutions are introduced.
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Affiliation(s)
- S U El-Kameesy
- a Physics Department, Faculty of Science , Ain Shams University , Cairo , Egypt
| | - E Salama
- a Physics Department, Faculty of Science , Ain Shams University , Cairo , Egypt
- b Basic Science Department, Faculty of Engineering , The British University in Egypt (BUE) , Cairo , Egypt
| | - S A El-Fiki
- a Physics Department, Faculty of Science , Ain Shams University , Cairo , Egypt
| | - M Ehab
- c Basic Science Department, Faculty of Engineering and Technology , Future University in Egypt , Cairo , Egypt
| | - W Rühm
- d Institute of Radiation Protection, German Research Center for Environmental Health , Neuherberg , Germany
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Stojanovska Z, Boev B, Zunic ZS, Ivanova K, Ristova M, Tsenova M, Ajka S, Janevik E, Taleski V, Bossew P. Variation of indoor radon concentration and ambient dose equivalent rate in different outdoor and indoor environments. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2016; 55:171-183. [PMID: 26943159 DOI: 10.1007/s00411-016-0640-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Accepted: 02/20/2016] [Indexed: 06/05/2023]
Abstract
Subject of this study is an investigation of the variations of indoor radon concentration and ambient dose equivalent rate in outdoor and indoor environments of 40 dwellings, 31 elementary schools and five kindergartens. The buildings are located in three municipalities of two, geologically different, areas of the Republic of Macedonia. Indoor radon concentrations were measured by nuclear track detectors, deployed in the most occupied room of the building, between June 2013 and May 2014. During the deploying campaign, indoor and outdoor ambient dose equivalent rates were measured simultaneously at the same location. It appeared that the measured values varied from 22 to 990 Bq/m(3) for indoor radon concentrations, from 50 to 195 nSv/h for outdoor ambient dose equivalent rates, and from 38 to 184 nSv/h for indoor ambient dose equivalent rates. The geometric mean value of indoor to outdoor ambient dose equivalent rates was found to be 0.88, i.e. the outdoor ambient dose equivalent rates were on average higher than the indoor ambient dose equivalent rates. All measured can reasonably well be described by log-normal distributions. A detailed statistical analysis of factors which influence the measured quantities is reported.
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Affiliation(s)
- Zdenka Stojanovska
- Faculty of Medical Sciences, Goce Delcev University, Krste Misirkov No.10-A, P. O. 201, 2000, Stip, Republic of Macedonia.
| | - Blazo Boev
- Faculty of Natural and Technical Sciences, Goce Delcev University, Krste Misirkov No.10-A, P. O. 201, 2000, Stip, Republic of Macedonia
| | - Zora S Zunic
- Institute of Nuclear Sciences "Vinča", University of Belgrade, P. O. Box 522, Belgrade, 11000, Serbia
| | - Kremena Ivanova
- National Center of Radiobiology and Radiation Protection, 3 Sv. Georgi Sofiyski st., 1606, Sofia, Bulgaria
| | - Mimoza Ristova
- Faculty of Natural Sciences and Mathematic, Institute of Physics, University in Ss. Cyril and Methodius, Arhimedova 3, 1000, Skopje, Republic of Macedonia
| | - Martina Tsenova
- National Center of Radiobiology and Radiation Protection, 3 Sv. Georgi Sofiyski st., 1606, Sofia, Bulgaria
| | - Sorsa Ajka
- Croatian Geological Survey, Sachsova 2, P. O. Box 268, Zagreb, Croatia
| | - Emilija Janevik
- Faculty of Medical Sciences, Goce Delcev University, Krste Misirkov No.10-A, P. O. 201, 2000, Stip, Republic of Macedonia
| | - Vaso Taleski
- Faculty of Medical Sciences, Goce Delcev University, Krste Misirkov No.10-A, P. O. 201, 2000, Stip, Republic of Macedonia
| | - Peter Bossew
- German Federal Office for Radiation Protection, div. SW 1.1, 120-130 Köpenicker Allee, 10318, Berlin, Germany
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