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Bachirou S, Saïdou, Kranrod C, Nkoulou Ii JEN, Bongue D, Abba HY, Hosoda M, Njock MGK, Tokonami S. Mapping in a radon-prone area in Adamawa region, Cameroon, by measurement of radon activity concentration in soil. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2023; 62:427-439. [PMID: 37535128 DOI: 10.1007/s00411-023-01042-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 07/22/2023] [Indexed: 08/04/2023]
Abstract
The radon-prone area of the Adamawa region in Cameroon is characterized by high natural radiation background resulting from the high concentrations of radium-226, thorium-232, and indoor radon. To produce a radon-risk map, radon measurements in soil were carried out in the city of Ngaoundere. The radon activity concentration in soil gas ranged from 256 to 166 kBq m-3 with a mean of 80 kBq m-3 and a standard deviation of 38 kBq m-3. The area is mostly classified as high risk (80%) according to the Swedish classification, and 20% as medium risk. A low-risk area was not observed. Granite-like geology sites were characterized by higher radon concentration. A ratio of about 295:1 was obtained for soil radon gas to indoor radon concentrations, with a positive correlation (R = 0.40), and a transfer factor of 3 per mil. These results demonstrate that in situ measurements of radon concentration in soil can provide accurate information on the level of indoor radon concentrations. Geostatistical and deterministic interpolation techniques have been used to obtain a radon map by comparing the suitability of ordinary kriging and inverse-distance-weighted (IDW) interpolation methods. It turned out that there is not much difference in the prediction errors of the two techniques (Root Mean Square Error = 34.4 for ordinary kriging and 34.3 for IDW). It is concluded that both methods give acceptable results. In situ measurements and geostatistical analysis allow assessment of expected indoor radon exposure in a given area at reduced costs and time required. However, for the investigated area, more research is needed to produce reliable radon-risk maps.
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Affiliation(s)
- Soumayah Bachirou
- Centre for Atomic Molecular Physics and Quantum Optics, University of Douala, PO Box 8580, Douala, Cameroon
- Local Material Promotion Authority, PO BOX 2396, Yaoundé, Cameroon
- Research Centre for Nuclear Science and Technology, Institute of Geological and Mining Research, PO Box 4110, Yaoundé, Cameroon
| | - Saïdou
- Research Centre for Nuclear Science and Technology, Institute of Geological and Mining Research, PO Box 4110, Yaoundé, Cameroon.
- Nuclear Physics Laboratory, Faculty of Science, University of Yaoundé I, PO Box 812, Yaoundé, Cameroon.
| | - Chutima Kranrod
- Institute of Radiation Emergency Medicine, Hirosaki University, Hirosaki City, Aomori, 036-8564, Japan
| | - Joseph Emmanuel Ndjana Nkoulou Ii
- Centre for Atomic Molecular Physics and Quantum Optics, University of Douala, PO Box 8580, Douala, Cameroon
- Research Centre for Nuclear Science and Technology, Institute of Geological and Mining Research, PO Box 4110, Yaoundé, Cameroon
| | - Daniel Bongue
- Centre for Atomic Molecular Physics and Quantum Optics, University of Douala, PO Box 8580, Douala, Cameroon
| | - Hamadou Yerima Abba
- Research Centre for Nuclear Science and Technology, Institute of Geological and Mining Research, PO Box 4110, Yaoundé, Cameroon
| | - Masahiro Hosoda
- Institute of Radiation Emergency Medicine, Hirosaki University, Hirosaki City, Aomori, 036-8564, Japan
- Department of Radiation Science, Hirosaki University Graduate School of Health Sciences, Hirosaki City, Aomori, Japan
| | - Moise Godfroy Kwato Njock
- Centre for Atomic Molecular Physics and Quantum Optics, University of Douala, PO Box 8580, Douala, Cameroon
| | - Shinji Tokonami
- Institute of Radiation Emergency Medicine, Hirosaki University, Hirosaki City, Aomori, 036-8564, Japan
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Akamba Mbembe B, Manga A, Mbida Mbembe S, Ele Abiama P, Ondo Meye P, Kofane TC, Ben-Bolie GH. INDOOR RADON (222RN) MEASUREMENTS AND ESTIMATION OF ANNUAL EFFECTIVE DOSE IN MVANGAN LOCALITY, SOUTH CAMEROON. RADIATION PROTECTION DOSIMETRY 2022; 198:1565-1574. [PMID: 36274266 DOI: 10.1093/rpd/ncac204] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2022] [Revised: 08/13/2022] [Accepted: 08/16/2022] [Indexed: 06/16/2023]
Abstract
The present work was aimed at measuring indoor radon activity concentrations in dwellings in Mvangan locality, South Cameroon, in order to assess the extent of measures that may be necessary for controlling public indoor radon exposure in this area. Measurements were carried out using passive solid-state nuclear track detectors (RADONAVA Inc., RadTrak2, Sweden) following ISO 11665-4 standard. Radon concentration ranged between 36 ± 20 and 150 ± 30 Bq m-3 with arithmetic and geometric means values of 64 ± 25 and 60 ± 1 Bq m-3, respectively. These mean values were greater than worldwide values presented by United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), which are, respectively, 40 and 30 Bq m-3. 96% of dwellings that have radon concentrations below the World Health Organization (WHO) reference level of 100 Bq m-3, whereas 4% of dwellings have radon concentrations higher than this level but lower than 300 Bq m-3, the International Commission on Radiological Protection (ICRP) reference level. Annual effective doses due to indoor radon ranged between 0.7 and 2.8 mSv y-1 with an arithmetic mean value of 1.2 ± 0.5 mSv y-1. These values were below the lower limit of the ICRP-recommended action level interval 3-10 mSv y-1. It has been observed that annual effective dose received by residents in cement bricks dwellings were not significantly different (P-value = 0.565) than those received by residents in mud dwellings in Mvangan locality. The mean number of persons expected to be diagnosed with or die from cancer (solid cancers and leukemia) were 162 ± 48 (61 ± 25 for males and 101 ± 41 for females) and 82 ± 24 (33 ± 13 for males and 49 ± 20 for females), respectively. The results obtained in this study prove that the populations of Mvangan locality are exposed to a relatively low potential risk of cancer incidence and mortality.
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Affiliation(s)
- Bertrand Akamba Mbembe
- Office of Regulatory and Technical activities, National Radiation Protection Agency, PO Box 33172, Yaoundé, Cameroon
- Department of Physics, University of Yaounde I, Faculty of Science, Nuclear Physics Laboratory, PO Box 1937, Yaoundé, Cameroon
| | - André Manga
- Nuclear Technology Section, Institute of Geological and Mining Research, PO Box 4110, Yaoundé, Cameroon
| | - Serge Mbida Mbembe
- Office of Regulatory and Technical activities, National Radiation Protection Agency, PO Box 33172, Yaoundé, Cameroon
- Department of Physics, University of Yaounde I, Faculty of Science, Nuclear Physics Laboratory, PO Box 1937, Yaoundé, Cameroon
| | - Patrice Ele Abiama
- Department of Physics, University of Yaounde I, Faculty of Science, Nuclear Physics Laboratory, PO Box 1937, Yaoundé, Cameroon
- Nuclear Technology Section, Institute of Geological and Mining Research, PO Box 4110, Yaoundé, Cameroon
| | - Philippe Ondo Meye
- Department of Physics, University of Yaounde I, Faculty of Science, Nuclear Physics Laboratory, PO Box 1937, Yaoundé, Cameroon
- Direction Generale de la Radioprotection et de la Surete Nucleaire, Ministere de l'Energie et des Ressources Hydrauliques, Libreville, Gabon
| | - Timoléon Crépin Kofane
- Department of Physics, University of Yaounde I, Faculty of Science, Nuclear Physics Laboratory, PO Box 1937, Yaoundé, Cameroon
| | - Germain Hubert Ben-Bolie
- Department of Physics, University of Yaounde I, Faculty of Science, Nuclear Physics Laboratory, PO Box 1937, Yaoundé, Cameroon
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Correlation between Ground 222Rn and 226Ra and Long-Term Risk Assessment at the at the Bauxite Bearing Area of Fongo-Tongo, Western Cameroon. RADIATION 2022. [DOI: 10.3390/radiation2040029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The aim of the current work was to study natural radioactivity in soil and the correlation between 222Rn and 226Ra in the ground and to assess the onsite and indoor long-term excess cancer risk at the bauxite bearing area of Fongo-Tongo in Western Cameroon. 222Rn was measured in the ground at a depth of one meter, using Markus 10 detector. 226Ra, 232Th, and 40K activity concentrations were measured in soil by two techniques, in situ and laboratory gamma spectrometry. The mean values of 222Rn concentrations in the ground were 69 ± 18 kBqm−3 for Fongo-Tongo and 82 ± 34 kBq m−3 for the locality of Dschang, respectively. The mean values of 226Ra, 232Th, and 40K activity concentrations obtained with in situ gamma spectrometry were 129 ± 22, 205 ± 61, and 224 ± 39 Bq kg−1 for 226Ra, 232Th, and 40K, respectively, and those obtained by laboratory gamma spectrometry were 129 ± 23, 184 ± 54, and 237 ± 44 Bq kg−1, respectively. A strong correlation between 222Rn and 226Ra activity concentrations determined by in situ and laboratory measurements (R2 = 0.86 and 0.88, respectively) was found. In addition, it is shown that the total excess cancer risk has a maximum value of 8.6 × 10−3 at T = 0 year and decreases progressively in the long term. It is also shown that 226Ra makes a major contribution, i.e., above 70%, to the total excess cancer risk.
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François K, Richard A, Samuel BG, Ayoba N, Yerima Abba H, Saïdou, Hubert BBG. Assessment of Natural Radiation Exposure Due to 222Rn and External Radiation Sources: Case of the Far North, Cameroon. HEALTH PHYSICS 2022; 123:00004032-990000000-00036. [PMID: 36067463 DOI: 10.1097/hp.0000000000001609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
ABSTRACT This paper assesses public exposure to natural radioactivity from radon and external radiation sources in the Far North region, Cameroon, and studies the correlation between radon data obtained using several techniques. The RADTRAK, RadonEye, and Markus 10 detectors were used to measure radon concentrations in dwellings and soil, respectively. To understand radon variations in the study area, a correlation coefficient between radon in soil and in dwellings was determined. The ambient equivalent dose rate was measured using a RadEye PRD-ER, and the effective doses from internal and external radiation were determined. In soil, 20% of the measuring points had a concentration above 50 kBq m-3, the action value for radon exposure from soil according to Swedish Radiation Protection Institute regulations. After 90 d of measurement using RADTRAK, half of the concentrations in the dwellings were greater than or equal to 160 Bq m-3, which is above the WHO reference level of 100 Bq m-3. The ambient equivalent dose rate and the external and internal radiation effective dose were 0.08 μSv h-1, 0.6 mSv y-1, and 2.86 mSv y-1, respectively. These results reveal a strong correlation between the radioactivity level of a locality and its geological and mineralogical structure. Although these different results in general do not present a very high risk of radiological exposure for the public, it is nevertheless necessary that the rules of radiation protection are respected in order to reduce it.
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Affiliation(s)
| | - Awe Richard
- Nuclear Physics Laboratory, Faculty of Science, University of Yaoundé I, Yaoundé, Cameroon
| | | | - Ndimantchi Ayoba
- Nuclear Physics Laboratory, Faculty of Science, University of Yaoundé I, Yaoundé, Cameroon
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Didier TSS, Yerima Abba H, Valentin V, Alidou M. Soil gas radon, indoor radon and its diurnal variation in the northern region of Cameroon. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2022; 58:402-419. [PMID: 35905287 DOI: 10.1080/10256016.2022.2102617] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 06/01/2022] [Indexed: 06/15/2023]
Abstract
Soil gas radon and indoor radon measurements have been carried out in Mayo-Louti and Benoué Divisions in northern Cameroon. Concentrations of radon in soil have been measured using Markus 10 at the depth of about 1 m. Radon concentration in soil varies from 0.9 to 13.8 kBq m-3 with a mean value of 4.6 kBq m-3. Average daily indoor radon concentrations measured with RadonEye+2 detectors vary from 7 to 60 Bq m-3 with an average of 17 Bq m-3. Indoor radon concentrations measured with passive RADTRAK detectors range between 15 and 104 Bq m-3 with a geometric value of 38 Bq m-3 and a geometric standard deviation of 1.5. This geometric value is lower than the value of 30 Bq m-3 given by UNSCEAR. Indoor radon inhalation dose ranges between 0.28 and 1.97 mSv a-1 with geometric value of 0.72 mSv a-1 (at 0.03 standard deviation). Outdoor radon inhalation ranges between 0.02 and 0.26 mSv a-1 with a mean value of 0.09 mSv a-1. The total annual effective dose due to indoor and outdoor radon exposure for this study area is 0.81 mSv a-1, less than 1.15 mSv a-1 the world average value given by UNSCEAR. There is no significant radiological risk for the inhabitants.
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Affiliation(s)
- Takoukam Soh Serge Didier
- Nuclear Physics Laboratory, Faculty of Science, University of Yaoundé I, Yaoundé, Cameroon
- National Radiation Protection Agency, Yaoundé, Cameroon
| | - Hamadou Yerima Abba
- Research Centre for Nuclear Science and Technology, Institute of Geological and Mining Research, Yaoundé, Cameroon
| | - Vaskanglang Valentin
- Atom and Radiation Laboratory, Faculty of Science, University of Maroua, Maroua, Cameroon
| | - Mohamadou Alidou
- National Advanced School of Engineering, University of Maroua, Maroua, Cameroon
- Department of Physics, Faculty of Science, University of Douala, Douala, Cameroon
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Ndjana Nkoulou Ii JE, Manga A, German O, Sainz-Fernandez C, Kwato Njock MG. Natural radioactivity in building materials, indoor radon measurements, and assessment of the associated risk indicators in some localities of the Centre Region, Cameroon. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:54842-54854. [PMID: 35314929 DOI: 10.1007/s11356-022-19781-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Accepted: 03/12/2022] [Indexed: 06/14/2023]
Abstract
The objective of the current study is to investigate the natural radioactivity of some building materials, the resulting long-term external and internal effective dose equivalents (EEDE and IEDE) analysis followed by indoor radon measurements, and the assessment of some radiological risk indicators associated with radon exposure. A total of 37 samples of building materials were analyzed with a sodium iodide detector (NaI (Tl)), and the computer code RESRAD-BUILD was used for the analysis of the EEDE and IEDE of the structural elements of the houses (walls and floor). For indoor radon measurements, 140 houses were selected, and in each of them was placed 01 RADTRAK dosimeter. Inhalation dose, total dose, and some radiological risk indicators were calculated. The specific activities of 226Ra, 232Th, and 40K for the overall sampled building materials were found to vary between 10 ± 2-52 ± 7, 10 ± 1-95 ± 10, and 31 ± 1-673 ± 20 Bq kg-1, respectively. The dwelling types with bare brick walls, cement mortar plastered walls, and concrete floors show EEDE and IEDE values well below the recommended limits. The corresponding dwelling type contributions to the measured average indoor radon concentration (42 ± 12 Bq m-3) are 22%, 13%, and 16%, respectively. Inhalation dose resulting from the measured indoor radon concentrations varies from 0.35 to 3.24 mSv y-1 with a mean value of 0.96 ± 0.55 mSv y-1, which represents about 65% of the total dose simulated (1.49 ± 0.88 mSv y-1) by the RESRAD-BUILD code. The overall analysis of indoor radon-related radiological risk indicators shows low levels of risk relative to permissible limits.
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Affiliation(s)
- Joseph Emmanuel Ndjana Nkoulou Ii
- Centre for Atomic Molecular Physics and Quantum Optics, University of Douala, PO Box 8580, Douala, Cameroon
- Research Centre for Nuclear Science and Technology, Institute of Geological and Mining Research, PO Box 4110, Yaoundé, Cameroon
| | - André Manga
- Research Centre for Nuclear Science and Technology, Institute of Geological and Mining Research, PO Box 4110, Yaoundé, Cameroon
| | - Olga German
- Division of Radiation, Transport and Waste Safety, Department of Nuclear Safety and Security, International Atomic Energy Agency, P.O. Box 100, 1400, Wagramerstrasse, 1020, Vienna, Austria
| | - Carlos Sainz-Fernandez
- Environmental Radioactivity Laboratory of the University of Cantabria (LaRUC), University of Cantabria, 39011, Santander, Cantabria, Spain
| | - Moïse Godfroy Kwato Njock
- Centre for Atomic Molecular Physics and Quantum Optics, University of Douala, PO Box 8580, Douala, Cameroon
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Calvente I, Núñez MI, Chahboun Karimi R, Villalba-Moreno J. Survey of Radon Concentrations in the University of Granada in Southern Spain. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph18062885. [PMID: 33799905 PMCID: PMC7998808 DOI: 10.3390/ijerph18062885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 03/07/2021] [Accepted: 03/09/2021] [Indexed: 11/16/2022]
Abstract
The objective of this pilot study was to gather and analyze data on radon concentrations in workplaces in three buildings of Granada University (Southern Spain) constructed in different centuries. All measurements were made at basement or ground floor level under normal use conditions except for one space (mineral store), in which measurements were compared between the door closed and open. Measurements were conducted during different time periods between October 2013 and March 2019 with a Radon-Scout PLUS portable Radonmonitor. The duration of continuous recordings at different sites ranged between 42 and 1104 h. Mean accumulated radon concentrations ranged between 12 and 95 Bq/m3, below the maximal level of 300 Bq/m3 set by the World Health Organization (WHO). Relatively high values were recorded in the oldest building (15th century), which was also poorly ventilated. Ventilation appeared to be an important factor in reducing radon levels, especially in areas less exposed to radon, such as Southern Spain.
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Affiliation(s)
- Irene Calvente
- Department of Radiology and Physical Medicine, School of Medicine, University of Granada, 18016 Granada, Spain; (I.C.); (J.V.-M.)
- Research Support Unit, Biosanitary Institute of Granada (ibs.GRANADA), San Cecilio University Hospital of Granada, 18016 Granada, Spain
| | - María Isabel Núñez
- Department of Radiology and Physical Medicine, School of Medicine, University of Granada, 18016 Granada, Spain; (I.C.); (J.V.-M.)
- Research Support Unit, Biosanitary Institute of Granada (ibs.GRANADA), San Cecilio University Hospital of Granada, 18016 Granada, Spain
- Biopathology and Regenerative Medicine Institute (IBIMER), University of Granada, 18016 Granada, Spain
- Correspondence: ; Tel.: +34-958-242-077
| | | | - Juan Villalba-Moreno
- Department of Radiology and Physical Medicine, School of Medicine, University of Granada, 18016 Granada, Spain; (I.C.); (J.V.-M.)
- Radiological Protection Service, University of Granada, 18010 Granada, Spain;
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