Journal of the European Radon Association

Review of radon research in Tanzania

Amos Vincent Ntarisa — Thu, 19 Dec 2024 07:54:55 -0800

In this paper, nine researched studies of radon concentrations in Tanzania were reviewed by searching specified databases from various search engines, such as Web of Science, Scopus, Google Scholar, Science Direct and PubMed for the studies published between the years 2010 and mid-April 2024 in English language to establish baseline data for the current research, which focused on Tanzania’s national radon survey and radon mapping strategy. The radon prediction map was created using well-known GIS software, ArcGIS 10.3. The results show that studies were conducted in central Tanzania close to Bahi and Manyoni uranium deposits, the Northern part of Tanzania at the Buhemba Gold mine and Tanzanite mines, and southern highlands at the Mkuju uranium project and Kiwira Coal mine. From the results of this review, the highest level of indoor radon concentration of 619 ± 59 Bq/m3 was recorded in Bahi Makulu, whilst the lowest average level of 19 ± 3 Bq/m3 was observed in Manyoni town. Radon in soil was conducted in Dodoma city only, and the mean was 59.8 kBq/m3. The average mean of radon in building materials is 74.6 Bq/m3, whilst no study has been found in the literature for radon in water. The lowest and highest radon concentration levels found in mining pits are 36 ± 5 and 4171.6 Bq/m3 reported from the Kiwira coal mine and Tanzanite Merelani mine, respectively. The results of this study emphasise the need for additional research on radon across the nation and raise awareness of the dangers and causes of radon exposure. Furthermore, this paper’s results will help develop the national indoor radon database and establish a regulatory framework for radon in buildings, soil, underground mines, building materials and water.

International intercomparison of Radon 222 activity concentration calibration facilities

Tue, 12 Nov 2024 12:55:13 -0800

The Coalition of International Radon Associations (COIRA) organised an inter-comparison of Rn-222 (radon) activity concentrations reported by calibration laboratories. A set of three AlphaGUARDs were used as transfer reference instruments against which to compare reported Rn-222 activity concentrations. Rn-222 activity concentration calibration facilities (sometimes termed chambers) from seven countries (Australia, US, Czech Republic, Spain, England, Sweden, Canada), and three continents participated in this project. The objective of the study was to provide information useful to calibration chamber operators and public health officials in the improvement of measurement and control systems, the maintenance of performance standards for measurements, and regulatory requirements for calibrations. This work builds upon and expands previous interlaboratory comparisons and provides data for estimating and using calibration uncertainty values as part of overall field error estimates and limits. A simple proportional difference between laboratories is presented here, calculated as the average for N hours of each hour’s difference between the laboratory’s concentration and the average of the three reference instruments. This percent difference ranged from less than 0.5% to just less than 8%. This work demonstrates that the ANSI/AARST standards limit of 8% for the estimated unexpanded (one sigma) individual calibration estimated uncertainty for continuous radon monitor calibration facilities in the US is achievable. However, given the few standards regarding calibration of Rn-222 activity concentration measurement instruments that themselves are often used to calibrate secondary and tertiary Rn-222 calibration facilities, there is a great need for continued interlaboratory comparisons to harmonise and document the calibration of Rn-222 activity concentrations.

A representative national indoor radon survey in Germany

Joachim Kemski, Valeria Gruber, Sebastian Baumann, Oliver Alber — Thu, 10 Oct 2024 08:07:08 -0700

Background: Radon is a carcinogenic indoor pollutant, which can cause lung cancer. Therefore, radon protection was included in national legislations and radon protection activities are carried out in Europe.

Objective: In Germany a nationwide survey to measure levels of indoor radon concentration in residential buildings was conducted.

Design: The survey was designed to represent the population. The measurements were taken for 6,000 households all over Germany for 12 months, with two measurements in each household with track etch detectors. The distribution follows administrative units (401 districts). In a first step, participants were acquired through a nationwide mailing with randomly chosen addresses. In a second step, more participants were brought in by specific advertising campaigns in local media.

Results: Results of approx. 6,500 households (= approx. 13,000 individual readings) were included in the study. The intention of a population-representative survey could not fully be accomplished, but the areal distribution of the participating households corresponded satisfactorily to the intended district-based distribution. The radon concentrations follow a log-normal distribution. The Germany-wide median is 44 Bq/m³, the geometric mean 49 Bq/m³, and the arithmetic mean is higher at 77 Bq/m³.

Discussion: The German reference level of 300 Bq/m³ is exceeded in about 3.5% of all measurements. Higher values, mainly due to geology, occur in the eastern and southern part of Germany. Known dependencies on building characteristics are confirmed, such as increased values in older buildings or on lower floors.

Conclusions: This survey can serve as a profound data basis for following radon studies in Germany and for an estimation of exposure of the population due to radon.

Prediction of the radon priority areas in the Slovak Republic and its experimental verification

Thu, 18 Apr 2024 06:11:05 -0700

Background: The identification of the areas with increased indoor radon levels, generally referred to as “radon priority areas”, is an internationally recognized issue. Many scientific studies propose methods for locating such areas using measured soil characteristics.

Objective: To utilize a modified Neznal radon potential classification for mapping radon potential across the Slovak Republic and experimentally verifying the predictions of radon priority areas.

Methods: The study applied a modified version of the Neznal radon potential classification, using measurements of soil air radon concentration and soil gas permeability, to develop a radon potential map for the Slovak Republic. Municipalities with high radon potential were primarily selected for the experimental verification of radon priority area predictions. The verification process involved comparing measured indoor radon activity concentrations against predicted values, which were derived from a previous study correlating averaged indoor radon activity concentrations with averaged Neznal radon potential for selected municipalities.

Results: The investigation revealed an approximately linear relationship between the measured indoor radon activity concentrations and their predicted values, with a correlation coefficient R² = 0.43. Notably, in one municipality predicted to have medium-high radon potential, indoor radon concentrations exceeded the reference level of 300 Bq.m^-3 even in buildings constructed after 2008, highlighting the significant influence of soil radon content on indoor levels despite stricter building material standards. The analysis of radon priority areas in relation to bronchial and lung cancer mortality data across various districts in Slovakia did not show statistically significant results.

Conclusion: The proposed method of predicting radon risk areas is important for radiation protection of the population against high effective doses of radon and can contribute to the successful implementation of the National Radon Action Plan of the Slovak Republic.

Radon exhalation and health hazard assessment for various ceramic tiles used in Bangladesh

Sopan Das, Shahadat Hossain — Mon, 15 Apr 2024 10:32:53 -0700

Objective: Among various building materials, tiles are the most used decorative materials used worldwide. For the safe use of tiles at home and workplace it is required to select them properly based on radiation dose due to radon and gamma emission.

Experiments: Among various tiles available in the market, 25 different types of tiles were collected for this experiment. Collected tiles are then ground and stored in sealed cans for secular equilibrium. To measure gamma activity due to the radionuclides ²²⁶Ra, ²³²Th, ⁴⁰K, High Purity Germanium (HPGe) detector was used. To store radon gas emitting from tiles, a big box was used. The activity concentration was then measured by a radon detector (RadonEye) by placing it inside the box.

Results and discussion: It was observed that ²²⁶Ra, ²³²Th, ⁴⁰K activity varies from 45 – 89 Bq/Kg, 77 – 110 Bq/Kg, and 321 – 694 Bq/Kg. The radium equivalent activity varies from 198.32 – 280.46 Bq/Kg, less than the recommended value of 370 Bq/Kg set by UNSCEAR (United Nations Scientific Committee on the Effects of Atomic Radiation). The activity concentration of radon varies from 31 – 71 Bq/m³. This is lower than the 300 Bq/m³ recommended by ICRP (International Commission on Radiological Protection). The radon exhalation rate varies from 0.179 – 0.409 Bqm⁻²h⁻¹. To assess radiological hazards associated with the tiles samples air absorbed dose rate, internal and external hazard index, gamma index, annual indoor and outdoor effective dose rate, and dose due to radon were also calculated.

Conclusion: Though the estimated values for external and internal hazards are below the recommended values, they may be safe for adults. As children have thinner skin and breathe more air due to high breathing frequency, they may receive more radiation than adults. Moreover, they are at a greater risk because of their developing bodies and long life expectancy post-exposure.

Experience from radon in soil gas comparison measurements held in Czech Republic and in other countries, 1992–2022

Milan Matolin, Matej Neznal — Thu, 28 Mar 2024 00:00:00 -0700

Radon ²²²Rn, an inert natural radioactive gas, a daughter product in the ²³⁸U natural decay series, a source of alpha radiation, together with its short-lived decay products is a dominant source of absorbed radiation doses in the population. Rocks and building materials are fundamental sources of radon in dwellings. Elevated indoor radon activity concentration in houses and workplaces, surpassing recommended reference levels, is not desirable. Since radon penetrates into the houses from the geological basement, various technical aids for protection of houses have been developed. Their individual application derives from the radon potential of a building site. Radon risk mapping of building sites became a standard procedure for gauging the local radon potential. Various instruments and techniques of measurements of radon activity concentration in soil gas (Bq/m³) at building sites are available. Since radon in soil gas and radon measurement techniques are affected by several natural and technical conditions, resultant values of radon risk mapping by individual organizations vary, sometimes fundamentally. Radon comparison measurements at selected reference sites are an important tool for single organizations to verify their radon measuring procedures and reliability of their reported results. Based on legislative regulations, comparison measurements at established radon reference sites are a part of the obligatory activities for radon risk mapping at building sites in the Czech Republic. Experience and analyses of 30-year radon in soil gas comparison measurements in the Czech Republic show the dispersion of values reported by participating organizations and indicate that more than 10% of participants do not fulfill the established local criteria. This paper introduces requirements for the establishment of radon reference sites, documents their natural variability, recommends the procedure of radon comparison measurement, and analyses its results. A long-term experience was gained by testing organizations from the Czech Republic (1992–2022) as well as from the international comparison measurements organized in the Czech Republic and in several other countries (2010–2021).

Radon levels in three fish rearing buildings at Cleghorn Springs State Fish Hatchery, Rapid City, South Dakota, USA

Thu, 18 Apr 2024 06:25:18 -0700

Fish hatchery workers may be exposed to potentially health-threatening radon gas liberated from ground water used during fish rearing. This study surveyed the radon levels in three fish rearing buildings (small tankroom, tankroom, and rearing pavilion) at Cleghorn Springs State Fish Hatchery, Rapid City, South Dakota, USA. Overall radon values ranged from below the detection limit in all three buildings to a high of 2,317.68 Bq/m³ (62.64 pCi/L) in the tankroom. The pavilion had the lowest mean ± SE value of 56.57 ± 40.71 Bq/m³ (1.23 ± 0.11 pCi/L), while the highest mean value of 796.21 ± 54.61 Bq/m³ (23.67 ± 1.34 pCi/L) was in the small tankroom. Maximum radon levels were 1,231.36, 2,317.68, and 365.93 Bq/m³ (33.28, 62.64, and 9.89 pCi/L) in the small tankroom, tankroom, and pavilion, respectively. Radon levels were significantly correlated with the number of tanks receiving water in both the small tankroom and tankroom, but no such correlation was observed in the relatively open-air pavilion. Even though the water at the hatchery was aerated outside, additional aeration from rearing tank spray bars inside the enclosed small tankroom and tankroom resulted in relatively high radon levels.