222Rn Concentrations Research Articles

Conversion factor and other variables in the indoor retrospective radon activity concentration studies

Estimation of indoor retrospective radon activity concentration can be performed by measuring the 210Po surface activity concentration of the radon progeny on mirrors. The conversion factor between the surface activity concentration of 210Po on mirrors and the retrospective activity concentration of 222Rn in the air was determined. Several places and some variables have been considered. Exposures were performed in places with moderate and high concentrations of 222Rn. The repeatability of results has been investigated. The dependence of concentration on exposure time has been checked. The effect of cleaning the mirror surfaces has been analyzed. The experimental results obtained for the possible 210Pb-210Po equilibrium inside the mirrors have also been studied and compared with the theoretically expected values.

Meteorological Approach in the Identification of Local and Remote Potential Sources of Radon: An Example in Northern Iberian Peninsula.

This paper presents a meteorological approach to identify local and remote sources driving the variability of surface daily radon concentrations. To this purpose, hourly 222Rn concentration and surface meteorological measurements, and air mass trajectories at Bilbao station (northern Iberian Peninsula) during the period 2017-2018 have been taken as reference. To investigate the potential transport pathways and potential 222Rn sources, the backward trajectory cluster analysis, trajectory sector analysis (TSA), and potential source contribution function (PSCF) are applied. On average, the diurnal 222Rn cycle shows the expected behaviour, with larger concentrations during the night and minimum concentrations during the daylight hours, with differences in the seasonal amplitudes. According to daily differences between maximum and baseline values, 222Rn daily cycles were grouped into six groups to identify meteorological conditions associated with each amplitude, and potential source areas and transport routes of 222Rn over Bilbao. The trajectory cluster and the TSA method show that the main airflow pathways are from the south, with small displacement, and the northeast, while the analysis of surface wind speed and direction indicates that the highest amplitudes of 222Rn concentrations are registered under the development of sea-land breezes. The PSCF method identified south-western and north-eastern areas highly contributing to the 222Rn concentration. These areas are confirmed by comparing with the radon flux map and the European map of uranium concentration in soil. The results have demonstrated the need in combining the analysis of local and regional/synoptic factors in explaining the origin and variability of 222Rn concentrations.

High Indoor Rn Concentration Mitigation in a Heritage Building: Case Study Analysis of the Applied Constructive Measures

Indoor radon (Rn) concentration is pointed out by the World Health Organization (WHO) as the second leading cause of lung cancer. Adopting mitigation measures based on ventilation procedures is an effective solution for most cases. However, the occurrence of abnormal concentrations of indoor Rn in heritage buildings, where most interventions are restricted, may lead to alternative remediation techniques. In these cases, constructive mitigation measures, such as the use of barrier membranes on the floor or specific coating mortars on the walls, can be adequate solutions. In the current investigation, two constructive measures were applied and analyzed sequentially. The preliminary long-term monitoring campaign registered extremely high indoor Rn concentration measurements. The application of a barrier membrane covering the floor of the test compartment allowed a 90% reduction in the average Rn concentration, but it nevertheless remained substantially above the recommended value of 300 Bq·m−3. Subsequently, a coating mortar was applied on the walls. The combined measures contributed to a total reduction of 94% in the average indoor Rn concentration, which remains slightly above the recommended exposure limit. Despite the verified reduction and the apparent effectiveness of the measures, it is still necessary to carry out more monitoring campaigns to test their general applicability.

Dose assessment for radon and thoron concentrations in iraqi thermostone bricks

This research aims to measure radon (222Rn) and thoron (220Rn) concentrations for selected thermostone bricks samples produced in Iraq. 222Rn and 220Rn concentrations were measured using the active method (RAD7 detector). Also, the inhalation dose for the year was calculated using the 222Rn and 220Rn concentrations. The results of this study indicated that the range of radon concentration values was between 8.00 Bq/m3 to 66.50 Bq/m3; its mean value was 28.22±3.89 Bq/m3. At the same time, the values of thoron concentrations ranged from 27.10 Bq/m3 to 129.00 Bq/m3, with a mean value of 55.46±7.15 Bq/m3. Also, the mean dose value associated with radon and thoron was 0.71±0.098 mSv/y and 0.31±0.039 mSv/y, respectively. According to preliminary research, the concentration of thoron in the current study was higher than that of radon except for two samples. In general, the values of doses from Iraqi thermostone brick samples were within the action level recommended by ICRP, 1993. Therefore, all samples in the present study didn't significantly affect the dose.

Radon Concentration Potential and Radiological Health Risks in Benue South Groundwater Sources

The attendant health consequences arising from both the consumption of thawed radon and the inhalation of released radon air and its progenies emanating from the various drinking water sources in our community underscores the relevance of the current research. This pioneering study attempts to evaluate the Rn-222 concentration, the annual committed effective dose (ACED) and the related health risk factors of randomly selected 26 water samples from Apa and Agatu Local Government Areas (LGAs), Benue South, Nigeria. The results of the analysis via liquid scintillation counter, revealed the highest radon values of 13.3651.065 Bq/l and 18.2481.740 Bq/l for well water samples higher than the action level of 11.1 Bq/l by USEPA were found in the villages of Apa and Agatu LGAs respectively, while 5.5510.479 Bq/l lower than the tolerance limit was recorded for the surface water samples. The annual committed effective doses estimated for the different ICRP age groups (3 months, 1 year, 5 years, 10 years, 15 years and above 17 years) were below the acceptable 1 mSv/y baseline but displayed a significant and consistent rise with the age and water consumption frequency of the populace. Excess life cancer risks (ELCR) and the induced lung cancer cases per year per million persons (LCC) for ingestion and inhalation of radon by the inhabitants of the study areas were calculated. ELCRing and ELCRinh mean values of the radionuclide showed different variations below the standard reference line. The average values recorded for the lung cancer cases due to ingestion and inhalation of radon (LCCing) and (LCCinh) and the probability of an individual developing cancer over a lifetime exposure to radioactive element (ELCR) were found to be significantly lower than the suggested 170 – 230 per year per million persons and 0.29 mSv/y global mean value respectively. This implies that the evaluated radon parameters for ingestion and inhalation in the study areas do not pose any immediate radiological health effects to members of the public but periodic monitoring of the quality of the groundwater sources should be encouraged.

Study of correlation between radon (222Rn) gas in soil and indoor radon with dose assessment in the bauxite bearing area of Fongo-Tongo, Western Cameroon

ABSTRACT The aim of the current work is to study the correlation between 222Rn gas in soil and indoor 222Rn concentrations. Markus 10 and RADTRAK detectors were used to measure 222Rn concentrations at 1 m depth in soil 30 points and 50 dwellings respectively. These concentrations varied from 35 kBq m−3 to 255 kBq m−3 with a geometric mean of 67 (18) kBq m−3, and from 85 Bq m−3 to 410 Bq m−3, with a geometric mean of 152 (26) Bq m−3 respectively in the soil gas and dwellings. In additional, 99% of the measurement points had concentrations higher than the limit value of 40 kBq m−3 according to the Swedish criterion for risk levels; 94% of the houses had radon concentrations higher than 100 Bq m−3, the reference value of the World Health Organization (WHO). When there was not a good air flow between the outside and the inside of the dwelling, the correlation coefficients were R2 = 0.82 and R2 = 0.73 respectively for the earthen and concrete dwellings. Under the best natural ventilation conditions, these correlation coefficients decrease significantly. Their values were R2 = 0.54 and R2 = 0.34 respectively for the earthen and concrete dwellings. Furthermore, a RadonEye +2 detector revealed a daily 222Rn accumulation reaching values of 800 Bq m−3 in some dwellings when all doors and windows were closed. Architecturally, dwellings built with sealed materials such as cement and concrete, whose do not facilitate 222Rn diffusion and transport, have lower 222Rn concentrations and effective dose than others These results show that 222Rn gas in soil and in confined air in dwellings are strongly correlated.

Hydrochemical and geological controls on dissolved radium and radon in northwestern Algeria hydrothermal groundwaters

This study presents the results of the first investigation on natural occurrence of radium and radon in Algerian thermal water systems. Activity concentrations of Rn and Ra isotopes were measured in sixteen hydrothermal springs of northwestern Algeria. Samples displayed high activities, especially for 222Rn, 224Ra and 226Ra (up to 377 × 103 Bq/m3, 730 Bq/m3 and 4470 Bq/m3, respectively). Approximately, 50% of the investigated springs displayed activities of combined long-lived Ra (226Ra + 228Ra) in excess of the maximum contaminant level (MCL) of the WHO and EPA for drinking water. Factors controlling the distribution of radionuclides in the aquifer system are investigated. The observed correlation between Ra isotope and TDS suggests that adsorption/desorption is not the dominant process controlling the distribution of Ra in waters. Our results indicate that the excess SO42− limits the concentration of dissolved Ba2+ and thereby, the elevated Ra activities in these hydrothermal systems are not simply limited by co-precipitation with BaSO4 (barite). The data shows that Ra activities are likely dominated by the recoil process of parent isotopes in the aquifer solids. The minimal abundance of clay minerals and oxides in the aquifer, in addition to thermal activities in northwestern Algeria, significantly enhances the mobilization of Ra into waters.

Evaluation of tectonically enhanced radon in fault zones by quantification of the radon activity index

This work highlights the importance of the Geogenic Radon Potential (GRP) component originated by degassing processes in fault zones. This Tectonically Enhanced Radon (TER) can increase radon concentration in soil gas and the inflow of radon in the buildings (Indoor Radon Concentrations, IRC). Although tectonically related radon enhancement is known in areas characterised by active faults, few studies have investigated radon migration processes in non-active fault zones. The Pusteria Valley (Bolzano, north-eastern Italy) represents an ideal geological setting to study the role of a non-seismic fault system in enhancing the geogenic radon. Here, most of the municipalities are characterised by high IRC. We performed soil gas surveys in three of these municipalities located along a wide section of the non-seismic Pusteria fault system characterised by a dense network of faults and fractures. Results highlight the presence of high Rn concentrations (up to 800 kBq·m−3) with anisotropic spatial patterns oriented along the main strike of the fault system. We calculated a Radon Activity Index (RAI) along north–south profiles across the Pusteria fault system and found that TER is linked to high fault geochemical activities. This evidence confirms that TER constitutes a significant component of GRP also along non-seismic faults.

Recent work with electronic radon detectors for continuous Radon-222 monitoring

Background: Sensitive electronic radon detectors can be an advantageous solution for continuous monitoring of radon dynamics in dwellings and workplaces. In order to investigate their applicability, such detectors must be subjected to adequate metrological assurance, and their performance in field conditions must be tested and evaluated.
 Objectives: To perform laboratory and field tests in order to evaluate the applicability of RadonEye+2 instruments for continuous radon monitoring.
 Results: In this work, we have performed laboratory tests of 36 RadonEye+2 detectors, which appear to have linear response for 222Rn concentrations below 3.5 kBq/m3 and a non-linear response (<15%) in the interval from 3.5 to 7 kBq/m3. Their response to 222Rn at 4.7 kBq/m3 is within 15% to the reference. In experiments with sharp variation of the 222Rn concentration, the detectors show fast response within 2 h. For the application of the detectors in dwellings and workplaces, we have developed a database, which collects, stores and visualises the RadonEye data. The database proved to be very useful tool, not only for data analysis but also for the identification of interruptions in the detectors operation and/or their connection to the internet. In a pilot 10-month-long study with three detectors located in different dwellings, we have observed more than 91% uptime of the online data collection from the detectors and more than 96% uptime of the data recording in the internal memory of the instruments.
 Conclusions: Overall, the results show that the RadonEye+2 instruments are very suitable for continuous radon monitoring and may be useful for follow-up of radon dynamics in long-term measurement campaigns in homes and workplaces.

Development of a “222Rn incremented method” for the rapid determination of air exchange rate using soil gas

The air exchange rate (AER) is a critical parameter that governs the levels of exposure to indoor pollutants impacting occupants’ health. It has been recognized as a crucial metric in spreading COVID-19 disease through airborne routes in shared indoor spaces. Assessing the AER in various human habitations is essential to combat such detrimental exposures. In this context, the development of techniques for the rapid determination of the AER has assumed importance. AER is generally determined using CO2 concentration decay data or other trace gas injection methods. We have developed a new method, referred to as the “222Rn incremented method”, in which 222Rn from naturally available soil gas was injected into the workplace for a short duration (∼30 min), homogenized and the profile of decrease of 222Rn concentration was monitored for about 2 h to evaluate AER. The method was validated against the established 222Rn time-series method. After ascertaining the suitability of the method, several experiments were performed to measure the AER under different indoor conditions. The AER values, thus determined, varied in a wide range of 0.36–4.8 h−1 depending upon the ventilation rate. The potential advantages of the technique developed in this study over conventional methods are discussed.

The 222Rn and CO2 soil gas distribution at Lembang Fault Zone, West Java - Indonesia

Series of 222 Rn measurements had been employed around the Lembang Fault Zone, West Java – Indonesia to investigate its relationship with the fault zone. Furthermore, the mechanism of 222Rn transport is also investigated by performing soil gas CO2 and its δ13C measurements. The evaluation of 222Rn concentration shows that 34% data are within threshold values with an average of 14,117 Bq/m3, with anomalous concentration greater than 20,000 Bq/m3. The concentration of CO2 in soil gas is varied from 72 ppm to 13,241 ppm and consisted of three populations, with 40% of the data above 655 ppm. The spatial distribution pattern shows that most of Lembang Fault Zone segment coincides with high 222Rn concentration indicating high permeability zone. Furthermore, the average 222Rn concentration in western part of the fault is higher than the eastern part and this may be correlated with higher seismic activities. In contrast to 222Rn, CO2 concentration shows less correlation to the fault structure. Based on δ13C values, the source of soil CO2 is dominated by atmospheric CO2, with minor mixing of biogenic origin. Although Lembang Fault Zone is located in the south of an active volcano, there is no indication of magmatic CO2 origin. The lack of correlation between 222Rn and CO2 suggests that there is no indication of 222Rn transport by CO2 as carrier gas.

Radiological risk associated with 222Rn occurrence in groundwater sources of rural communities in the semiarid region of Paraíba, Brazil.

Rural and isolated communities traditionally lack adequate water treatment and distribution systems, and water quality assessment often does not include radioactivity measurement. Here we present, for the first time, the results of Rn measurements and the evaluation of the associated dose in groundwaters of rural communities in a semiarid area in Paraiba State, Brazil. Water samples were analysed using a low-level liquid scintillation spectrometer (LSS). Radon concentrations were higher than EPA and WHO recommended levels in water for most of the wells (range of 5.5-1107.0Bq/L, average 252.8Bq/L). Higher Rn concentration was measured in deeper wells and located in area rich in granite and diorite rocks. The annual effective doses varied between 0.021 and 4.317mSv/y for infants, 0.016-3.182mSv/y for children, and 0.015-3.022mSv/y for adults, exceeding, in some cases, the 1mSv/y reference level recommended by the WHO and UNSCEAR for the public. Thus, water consumption from half of the wells should be avoided unless adequate treatment is provided. Results highlight the need to perform actions to supply water with appropriate quality to the local population.

Assessment of soil-gas radon concentration over lithologies: a case study from district Karak, Khyber Pakhtunkhwa, Pakistan.

The current study is aimed to determine the variation of soil-gas radon concentrations over different rock formations representing diverse lithologies in the district of Karak, Khyber Pakhtunkhwa, Pakistan. The stratigraphic units were grouped on the basis of lithological contents into four categories, i.e., limestone, evaporites, claystone/mudstone, and sandstone. The highest average soil-gas 222Rn concentration (544Bq/L) was found in the uranium-bearing Dhok Pathan Formation of the Pliocene age, while the lowest radon levels (0.15Bq/L) were observed in the salt-bearing strata of Bahadurkhel Salt of Eocene age showing the non-uraniferous nature of the salt. High radon potential associated with the Dhok Pathan Formation is likely to be related to the high degree of uranium mineralization which is contributing to the elevated soil-gas radon levels. The study revealed that the soil-gas radon concentration in all lithologies is varying in the order of RnSandstone > RnLimestone > RnClaystone/Mudstone > RnEvaporites with the highest radon levels in the sandstone unit of uranium-bearing Dhok Pathan Formation. High fluctuations of soil-gas radon levels observed in this study evidently show that lithology and uranium mineralization have strong control over the 222Rn concentrations.

Exploration of Deep Ocean Ferromanganese Nodule Fields Using Radon as a Tracer

AbstractFerromanganese nodules (Fe‐Mn nodules) are considered as potential sources of in‐demand metals (such as manganese, cobalt, nickel, copper, and rare‐earth elements) that are used in high‐technology industries. The resource potential of Mn nodules in the world ocean remains uncertain due to technological and financial challenges. Here we propose an effective tracer: the natural radioactive radon isotope (222Rn) to assess the abundance of Fe‐Mn nodules on the sea floor. Significant linear relationships were observed between benthic excess 222Rn fluxes and concentrations with Fe‐Mn nodule occurrence and coverage on the global seafloor. Benthic excess 222Rn flux >107 dpm/m2/yr or bottom water 222Rn concentrations >2,000 dpm/m3 indicate the possibility of Fe‐Mn nodules occurrence at >80% and seabed coverage of >25%. Our results indicate radon, relatively easy to measure, could serve as a novel and efficient tool for targeting Fe‐Mn nodule resources in the global abyssal ocean.

Correlation between Ground 222Rn and 226Ra and Long-Term Risk Assessment at the at the Bauxite Bearing Area of Fongo-Tongo, Western Cameroon

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.

Radon concentration variations at the Yangyang underground laboratory

The concentration of222Rn in the air has been measured in the 700 m-deep Yangyang underground laboratory between October 2004 and May 2022. The average concentrations (spreads) in two experimental areas, called A6 and A5, were measured to be 53.4 Bq/m3(13.9 Bq/m3) and 33.5 Bq/m3(7.9 Bq/m3), respectively. The lower value in the A5 area reflects the presence of better ventilation. The radon concentrations sampled within the two A5 experimental rooms’ air are found to be correlated to the local tunnel temperature outside of the rooms, with correlation coefficientsr= 0.22 andr= 0.70. Therefore, the radon concentrations display a seasonal variation, because the local temperature driven by the overground season influences air ventilation in the experimental areas. A sinusoidal function with a period of 1 year was used to fit the radon concentration data of both underground areas finding a maximum amplitude on August, 31 ± 6 days.

Research on Three-level Enrichment Method Based on 222Rn.

Various low-concentration inert gases, including 222Rn, 133Xe, and 85Kr, pollute the atmosphere near nuclear facilities (e.g., nuclear power plants or reprocessing plants). Owing to the detection limits of instruments, it has become urgent to determine the concentration of these gases efficiently and perform their online monitoring. However, current technologies are limited by low enrichment efficiencies. In this study, a high-pressure, low-flow, large-volume, and high-efficiency adsorption method has been proposed along with a high-temperature, low-pressure, high-flow, and small-volume rapid desorption and collection method, which are based on the gas enrichment principle of activated carbon. The results demonstrated that when dynamic adsorption was implemented using a two-level enrichment method, the final desorbed gas concentration was proportional to the volume ratio of both the large and small activated carbon beds. At a volume ratio of 15:1, 222Rn concentration increased from 110 to 21,016 Bq m-3 after the two-level enrichment; meanwhile, 222Rn concentration increased from 110 to 42,012 Bq m-3 after three-level enrichment. The three-level enrichment technology provides technical support for the enrichment of low-concentration inert gases in the environment, while offering an important technical foundation for improving the monitoring of low-concentration inert gases in specific environments as well as the atmospheric environment.

Comparison of Radon Gas in Different Water Samples at Al Haidariya City, Iraq

This study aims to measure the radon (222Rn) concentrations in the three types of water (groundwater, surface water, and health drinking water) in Al Haidariya city at Al-Najaf governorate, Iraq using RAD-7 detectors. The results show that the average of 222Rn in groundwater, surface water, and health drinking water were (0.276 Bq/L, 0.182 Bq/L and 0.132 Bq/L3) respectively, whereas the average of annual effective dose was (0.706 μSv/y,0.46 μSv/y and 0.337 μSv/y), respectively, While lifetime cancer risk (×10-4) with an average (0.027, 0.018 and 0.013) respectively. According to the results of 222Rn, the samples can be arranged in order groundwater, surface water and health drinking water. The results of the radon concentrations and the rate of annual effective dose for all water samples were significantly lower than the USEPA and WHO recommended respectively. The environmental effects of radioactive radon gas are almost non-existent, because the lifetime risk of cancer in all samples is less than the permissible safety limit for healthy drinking water, and therefore it does not affect human health.

Assessment of radon levels in groundwater in the city of Makkah, KSA

Groundwater has been gaining increasing interest as an imperative and crucial water resource. Its demand has been rising swiftly in the closing numerous many years with the overpopulation of and increasing standards of dwelling in the town of Makkah. In recent years, significant activity has arisen related to the natural radioactivity in water. Radon (222Rn) concentrations were measured in ten groundwater samples from distinct locations in the Makkah area, Saudi Arabia, using RAD7 which an electronic 222Rn gas detector linked to a RAD7- H2O accessories (Durridge -USA). The evaluated concentrations of 222Rn in the ground water samples of our study ranged from 0.426 to 18.628 Bq/l with a mean 2.851 Bq/l, whilst the dose of 222Rn due to drinking water in the stomach diverse from 0.089 to 3.912 µSv/y (average: 0.599) and the dose of 222Rn in the lungs different from 1.073 to 46.944 µSv/y (average: 7.184). The total annual effective dose (µSv/y) ranged from 1.163 to 50.855 µSv/y with a mean of 7.783 µSv/y. The effects of the existing learn about point out that the 222Rn concentrations in most groundwater samples taken around Makkah have been under the action levels recommended via USEPA, UNSCEAR, the EU Council, and the WHO.

Long term measurement of the ^{222}Rn concentration in the Canfranc Underground Laboratory

We report the results of 6 years (2013–2018) of measurements of ^{222}Rn air concentration, relative humidity, atmospheric pressure and temperature in the halls A, B and C of the Canfranc Underground Laboratory (LSC). We have calculated all the Pearson correlation coefficients among these parameters and we have found a positive correlation between the ^{222}Rn concentration and the relative humidity. Both correlated variables show a seasonal periodicity. The joint analysis of laboratory data and 4 years (2015–2018) of the meteorological variables outside the laboratory shows the correlation between the ^{222}Rn concentration and the outside temperature. The collected information stresses the relevance of designing good Rn-mitigation strategies in current and future experiments at LSC; in particular, we have checked for two years (2017–2018) the good performance of the mitigation procedure of the ANAIS-112 experiment. Finally, we have monitored (2019–2021) for 2 years of live time, the radon-free air provided by the radon abatement system installed in the laboratory.