Distribution Of Radon Concentration Research Articles

Modeling of indoor 222Rn in data-scarce regions: an interactive dashboard approach for Bogotá, Colombia

Abstract. Radon (222Rn) is a naturally occurring gas that represents a health threat due to its causal relationship with lung cancer. Despite its potential health impacts, several regions have not conducted studies, mainly due to data scarcity and/or economic constraints. This study aims to bridge the baseline information gap by building an interactive dashboard (http://ircmodelingdashboard.eu.pythonanywhere.com/, last access: 17 April 2024) that uses inferential statistical methods to estimate the spatial distribution of indoor radon concentration (IRC) for a target area. We demonstrate the functionality of the dashboard by modeling IRC in the city of Bogotá, Colombia, using 30 in situ measurements. IRC measured was the highest reported in the country, with a geometric mean of 91±14 Bq m−3 and a maximum concentration of 407 Bq m−3. In 57 % of the residences, RC exceeded the WHO's recommendation of 100 Bq m−3. A prediction map for houses registered in Bogotá's cadaster was built in the dashboard by using a log-linear regression model fitted with the in situ measurements, together with meteorological, geologic and building-specific variables. The model showed a cross-validation root mean squared error of 57 Bq m−3. Furthermore, the model showed that the age of the house presented a statistically significant positive association with RC. According to the model, IRC measured in houses built before 1980 presents a statistically significant increase of 72 % compared to IRC of those built after 1980 (p value = 0.045). The prediction map exhibited higher IRC in older buildings most likely related to cracks in the structure that could enhance gas migration in older houses. This study highlights the importance of expanding 222Rn studies in countries with a lack of baseline values and provides a cost-effective alternative that could help deal with the scarcity of IRC data and get a better understanding of place-specific variables that affect IRC spatial distribution.

Исследование аэрогазодинамических процессов переноса радона из горных массивов

Introduction. Drying tailings are a source of gaseous chemicals, in particular radon222, which is carried by air currents along the slopes of the gorge. These processes need constant monitoring. Purpose of research. Establishment of climatic conditions most influencing the measurements of mountain radon and its dispersion in the atmosphere. Research methods and materials. The data of weather stations located in the Alagir mountain gorge and the data of the mathematical model of this gorge were used to establish the characteristic wind roses at the points of the gorge selected for field measurements of mountain radon. Research results. It has been established that at the nearby points of the mountain gorge, the prevailing direction and strength of the wind can differ significantly. The differences depend on the landscape features of the surface of the slopes of the mountain gorge. This factor determines the direction of migration of chemical elements and decay products of mountain radon. This conclusion is confirmed by direct measurement of wind speed at two points in the gorge, as well as by the results of mathematical modeling. Discussion of research results. A preliminary calculation of the passive impurity concentration field within the mountain gorge shows the most characteristic places on the slopes of the gorge from the point of view of measurements. Preliminary algorithm for choosing the location of measurements. Determination of 210Pb content in natural «traps» or sediments can determine the migration paths of «mountain» radon and estimate the magnitude of its interaction with the nature of the gorge, subject to the following assumptions: 1) certain sampling sites are not subject to significant seasonal disturbances; 2) natural and climatic conditions, especially the amount of precipitation, in the studied gorge should not have abnormal changes before sampling; 3) sampling should preferably be carried out in autumn on fallen leaves in hollows, where post-sedimentary migration is limited. Approbation of the proposed measurement technique is discussed. Conclusion. The prevailing winds in the side arms of mountain gorges can differ significantly from the wind rose observed in the main part of the gorge and are determined mainly by landscape features near the observation point. This must be taken into account when measuring and analyzing the direction of migration of chemicals in mountain gorges. Mathematical modeling of aerodynamic processes in mountainous regions is a proven method for studying physical processes in mountain gorges, as well as the processes of dispersion of volatile geochemical elements emitted by sources in mountain gorges. It is shown that at the nearby points of the mountain gorge, the wind roses can differ significantly, which is confirmed by both measurements and mathematical modeling. This dictates the need for observations and taking into account the local wind rose at each measurement point. The results of radon measurements are presented, confirming the effectiveness of the proposed technique. Resume. 1. The article presents the results of mathematical modeling of aerodynamic processes in mountain gorges and the spread of gaseous impurities in the air. 2. It has been established that wind roses at nearby points on the slopes of a mountain gorge can differ significantly, both in the results of the mathematical model and in the results of measurements from weather stations. It is shown that the agreement between the modeling and measurement results is satisfactory. 3. The research results can be useful in planning measurements of radon concentrations as a predictive map of the distribution of mountain radon concentrations.

Influence of temperature on the radon concentration distribution in ramp under low-speed wind field: A numerical simulation study

By introducing the parameters of radon exhalation rate and radon diffusion coefficient, the distribution of radon concentration field on ramp under the condition of superposition of temperature field and flow field is simulated. The simulation results show that the distribution of radon concentration in the ramp under the condition of low-speed ventilation is greatly affected by the temperature field and flow field, and the change of radon exhalation caused by temperature is the main factor leading to the change of radon concentration in the ramp. The change of temperature will cause the overall increase of radon concentration in the ramp. Under the condition of constant flow field, the radon concentration in the chamber is more than two times higher than the average radon concentration in the ramp. Some areas severely exceeded the limit.

Spatial distribution of radon concentration and risk evaluation through consumption of groundwater in the District of Kotli, Azad Jammu and Kashmir

Radon (222Rn) is naturally readily water-soluble, posing a cancer risk to the exposed community. Human exposure in the community may occur via 222Rn intake in drinking water. Groundwater is used for drinking and other domestic purposes in the region. Higher concentrations of 222Rn in groundwater have been reported near Kotli district, Azad Jammu, and Kashmir. This investigation aimed to measure 222Rn concentrations in groundwater and evaluate the associated risk assessment for children and adults in the Kotli district. 222Rn concentrations were measured in randomly collected groundwater samples of Kotli (n = 25) and Sehnsa (n = 15) towns in the Kotli district using the portable Radon Detector (RAD7, Durridge Company, United States of America). Among the studied areas, the Sehnsa showed a higher average 222Rn concentration (7.6 ± 0.2 Bq/L) in groundwater compared to Kotli (6.0 ± 1.9 Bq/L). The average concentrations of 222Rn were found within the recommended limit (11.1 Bq/L) of the United States Environmental Protection Agency (USEPA), except for 10% of sampling sites. 222Rn concentrations were used for the calculation of total effective dose for ingestion and inhalation pathways (EwTotal) values for infants (24.5 ± 7.5 and 30.7 ± 0.9 μSv/a), children (18.1 ± 5.5 and 23.5 ± 0.7 μSv/a), and adults (18.1 ± 5.5 and 22.7 ± 0.3 μSv/a) in the Kotli and Sehnsa, respectively. This study noted that EwTotal and estimated lifetime cancer risk (ELCR) values were found within the World Health Organization (WHO) and European Commission (EU) acceptable limits (<100 μ Sv/a and 0.1 × 10−3).

Distribution of soil gas radon concentration in north-eastern Sicily (Italy): hazard evaluation and tectonic implications

Distribution of soil gas radon concentration in north-eastern Sicily (Italy): hazard evaluation and tectonic implications

A national comparison between the collocated short- and long-term radon measurements in the United States.

Knowing the geographical and temporal variation in radon concentrations is essential for assessing residential exposure to radon, the leading cause of lung cancer in never-smokers in the United States. Tens of millions of short-term radon measurements, which normally last 2 to 4 days, have been conducted during the past decades. However, these massive short-term measurements have not been commonly used in exposure assessment because of the conflicting evidence regarding their correlation with long-term measurements, the gold standard of assessing long-term radon exposure. We aim to evaluate the extent to which a long-term radon measurement can be predicted by a collocated short-term radon measurement under different conditions. We compiled a national dataset of 2245 pairs of collocated short- and long-term measurements, analyzed the predictability of long-term measurements with stratified linear regression and bootstrapping resampling. We found that the extent to which a long-term measurement can be predicted by the collocated short-term measurement was a joint function of two factors: the temporal difference in starting dates between two measurements and the length of the long-term measurement. Short-term measurements, jointly with other factors, could explain up to 79% (0.95 Confidence Interval [CI]: 0.73-0.84) of the variance in seasonal radon concentrations and could explain up to 67% (0.95 CI: 0.52-0.81) of the variance in annual radon concentrations. The large proportions of variance explained suggest that short-term measurement can be used as convenient proxy for seasonal radon concentrations. Accurate annual radon estimation entails averaging multiple short-term measurements in different seasons. Our findings will facilitate the usage of abundant short-term radon measurements, which have been obtained but was previously underutilized in assessing residential radon exposure. Tens of millions of short-term radon measurements have been conducted but underutilized in assessing residential exposure to radon, the greatest cause of lung cancer in non-smokers. We investigate the correlations between collocated short- and long-term measurements in 2245 U.S. buildings and find that short-term measurements can explain ~75% of the variance in subsequent long-term measurements in the same buildings. Our results can facilitate the usage of massive short-term radon measurements that have been conducted to estimate the spatial and longitudinal distribution of radon concentrations, which can be used in epidemiological studies to quantify the health effects of radon.

Analysis for distribution estimation of soil radon concentration and its influencing factors: A case study in decommissioned uranium mill tailings pond

The present study focuses on the distribution law of soil radon concentration and its influencing factors under natural conditions. Field investigation of the radon concentration, temperature, soil moisture and salinity at different depths (20–80 cm) of beach surface of a decommissioned uranium mill tailings pond in southern China have been conducted. The Pearson Correlation Coefficient (PCC) and Grey Relation Analysis (GRA) models were adopted to linear/nonlinear analyze the correlation of radon concentration with soil depth, temperature, moisture and salinity. The results of PCC model show that the correlations of radon concentration along with soil moisture, temperature and soil depth are more significant than that of salinity, which is consistent with the results of GRA model on the whole. The correlation of soil moisture on radon concentration distribution was slightly greater than that of soil temperature.

Short- versus long-term tests of indoor radon for risk assessment by Monte-Carlo method towards effective measurement strategy.

There now exists a broad consensus among the European radon community members that long-term measurements are the best practice in managing the risk of indoor radon exposure. This, not with standing the fact that <1% of buildings have been tested in Europe so far. At the same time, US' experience over the years shows more effective regulation has been accomplished through tests that are short-term. This study quantifies the uncertainty of collective risks obtained independently through short- and long-term measurements under the same conditions using the Monte Carlo method that takes into account the number of measurements, as well as the diversity of the spatial distribution of radon concentrations in representative samples of buildings. Simulation results have shown that contrary to the erroneous practice of the European radon community, the accuracy of the assessment of the collective risk due to radon exposure does not in fact depend on the duration of the indoor test at all. The main problem remains ensuring the existance of a representative sample of buildings, especially given limited number of tests. In this regard, recommended is a revision of the regulatory documents of IAEA, ICRP, WHO, and ISO focusing on (i) the principle of the effective measurement strategy based on rational ISO/IEC concepts, (ii) the mass measurements via short-term tests, and (iii) the societal engagement in measurements.

Seasonality of Radon-222 near the surface at King Sejong Station (62°S), Antarctic Peninsula, and the role of atmospheric circulation based on observations and CAM-Chem model

We examined the seasonal cycle of radon concentration observed at King Sejong Station (KSG, 62°S), Antarctic Peninsula, during the period 2013–2016. The distribution of monthly radon concentration was found to be highly positively skewed from March through October (austral autumn to spring) due to large numbers of short-lived periods of high radon concentration. The global atmospheric chemistry model (CAM-Chem), which includes all global terrestrial sources of radon except for those in Antarctica, well reproduces the observed seasonal cycle of monthly-mean radon concentration at KSG. Further offline experiments suggest that uncertainties in radon emissions over South America and the Southern Ocean should be improved for the simulations of radon in Antarctica. The results demonstrate that seasonally varying transport of radon in the boundary layer from South America substantially affects the seasonality of monthly mean radon concentration at KSG. The composite analyses further reveal that high radon events at KSG are the result of a distinct east-west dipole-like structure associated with surface cyclonic circulation over the Bellingshausen Sea and anticyclonic circulation in the Weddell Sea. This atmospheric pattern provides favorable conditions for radon transport into KSG from the northwest. The relationship between radon concentration at KSG and climate variability is also discussed in this study.

222Rn Activity Concentration Measurement and its Radiological Risks in the Environment of Barserin Village, Erbil-Iraq

222Rn Activity Concentration Measurement and its Radiological Risks in the Environment of Barserin Village, Erbil-Iraq

Spatial distribution of radon concentrations in groundwater and annual exposure doses in Mirpur District Pakistan

Radon (222Rn) is a readily water-soluble naturally occurring carcinogenic gas and poses serious threats to a humans’ health. This study aimed to investigate 222Rn concentration in groundwater and associated health risks. For this purpose, groundwater samples (n = 36) were collected from the Mirpur District (3 towns: Jatlan, Mirpur, and Dadyal), Pakistan. The concentration of 222Rn in groundwater samples was measured by the RAD7 (Durridge Company, USA). Results showed that the average 222Rn concentrations in groundwater were 5.99 ± 1.41, 5.39 ± 0.89, and 13.6 ± 3.33 Bq/l of Jatlan, Dadyal, and Mirpur, respectively. These results revealed that mean concentrations of 222Rn were found within the maximum threshold limits (MCL, 11.1 Bq/l) of the United States Environmental Protection Agency (USEPA), however, that of Mirpur surpassed these limits. The concentrations of 222Rn in Mirpur District were evaluated for the annual effective doses (EwTotal). Results revealed that mean EwTotal values of the three studied sites in Mirpur District were found lower than the threshold limit (100 μSv/a), except 6% of sampling sites in the Mirpur. Higher EwTotal values than the WHO threshold limit in the Mirpur could pose threat to human health. The estimated lifetime cancer risk showed higher values along with the Mirpur of the study area. Therefore, this study recommends that water in the Mirpur area should be aerated or heated before consumption to avoid 222Rn impact on human health.

Pilot groundwater radon mapping and the assessment of health risk from heavy metals in drinking water of southwest, Nigeria

Radon and heavy metals are sources of groundwater pollution and are identified as potential carcinogens. Southwest Nigeria's populace mostly relies on groundwater source for drinking. This study aims to map radon distribution in groundwater of southwest Nigeria and to determine the health risk of radon and heavy metal in drinking water. Radon concentrations of 145 groundwater samples were measured using RAD7 electronic radon detector and heavy metal concentrations of 52 groundwater samples were measured using atomic absorption spectrophotometer. Radon concentration distributions were delineated using geographical information system. Radon concentration of water samples ranges between 1.6 Bq l−1 and 271 Bq l−1 with an average value of 35.9 ± 38.4 Bq l−1. The average groundwater radon concentration is higher than US-EPA recommended level of 11.1 Bq l−1 but lower than the WHO recommended limit of 100 Bq l−1. The estimated average annual effective radiation doses to infants, children, and adults are 29 μSvy−1, 41 μSvy−1 and 92 μSvy−1 respectively. The radon distribution map of the study area reveals regions of high, medium, and low groundwater radon concentrations. The average concentration values of heavy metals in groundwater samples are of the order Mn > Zn > Pb > Cu > Cr > Ni > Cd. 84% of groundwater exhibits good to excellent quality in terms of heavy metal pollution. However, about 16% of the samples which lie in the sedimentary regions of Ogun and Lagos States exhibit poor to very poor quality. Overall, ingestion of groundwater in the study area may not pose a serious health hazards from radon ingestion and heavy metal toxicity.

Identification of sources with abnormal radon exhalation rates based on radon concentrations in underground environments

When there is poor ventilation or an irregular radon exhalation rate in an underground environment, it is necessary to judge whether the radon concentration is abnormal. To protect personal safety and health from radon gas, it is necessary to track the location of an abnormal radon source and measure its release rate to formulate emergency control and eradication measures. However, in an underground environment, it is impossible to fully monitor the radon concentration at every location, and as a result, blind spots are present, making it difficult to obtain timely early warnings in the event of an abnormal radon exhalation rate. Based on the distribution of radon concentration in an underground environment, this research establishes a theoretical mathematical model of an underground ventilation network containing radon. We combined particle swarm optimization with the long short-term memory (PSO-LSTM) method, which uses part of a time series signal of monitored radon concentrations to track the location of an abnormal radon source and determine an abnormal radon exhalation rate. Performing experiments of theoretical examples and actual underground ventilation environment examples, we prove the necessity of optimizing the monitoring position of the angle-connected ventilation network. The results show that the PSO-LSTM model based on radon concentration monitoring can process time series signals. Its accuracy and decision coefficient greater that is than 0.9 indicate the reliability of the model and method.

Analysis of the spatial distribution of the indoor radon concentration in school's buildings in Plovdiv province, Bulgaria

This paper presents an evaluation of the indoor radon spatial variation between and within school buildings. Radon measurements were carried out in 331 rooms of 16 school buildings in 5 municipalities of Plovdiv province, Bulgaria. They were performed with CR-39 nuclear track detectors exposed over an 8-month period from September 2018 to April 2019. The arithmetic and geometric means together with corresponding standard deviation and geometric standard deviations of the indoor radon concentration were 160 ± 175 Bq/m3 and 108 */2.35 Bq/m3, respectively. The best data fit was achieved with a Weibull 3-parameter function (Kolmogorov-Smirnov test, p = 0.2916). The effect of the school location and various building characteristics on the indoor radon concentration distribution within a province was investigated. The analyses showed that the factor “year of building construction”, which is in general related with the technical condition of the building, imposed the highest impact on the indoor radon concentration difference between schools. The vertical and horizontal components of the indoor radon spatial variability within a school were analysed as well. The results concerning the radon variation within schools could be used to optimize future radon school surveys. In this paper, quality control for indoor radon measurement procedures and radon health impact assessments was included.

Spatial distribution of radon concentrations in Balakot-Bagh (B–B) Fault Line and adjoining areas, Lesser Himalayas, North Pakistan

A study involving soil radon monitoring using RAD-7 instrument was carried out near Balakot-Bagh (B-B) Fault line hit by a 7.6 magnitude earthquake in October 2005. The study aimed to determine the spatial distribution of soil radon gas levels and the relationship between the soil radon gas and fracture density. Eleven soil samples were collected near the fault line, and 56 more samples (fourteen each from the adjoining district/area). Field measurements were made in the summer season of 2013, as a part of continuous measurement for regular monitoring the area for radon emanation and for observing the anomalies with previous values. The study area is located in Lesser Himalayas, North Pakistan, the Balakot–Bagh (B–B) fault in the Hazara–Kashmir Syntaxis. Soil gas radon concentrations were found higher near the Balakot-Bagh Fault line with an average value of 11.9 $${\text{kBq}}\;{{\text{m}}^{ - 3}}$$ compared to other sites of the study area with an average value of around 6.5 $${\text{kBq}}\;{{\text{m}}^{ - 3}}$$ . The radon value near the fault line is 70% higher as compared to the surrounding area.

CFD based simulation of indoor radon distribution from the use of different brands of decorative glazed tiles made in China

ABSTRACT The radon exhalation rates of the surface of 10 different brands of glazed tiles made in China are measured and assessed. The experimental results reveal that the values of radon exhalation rate from the surface of glazed tiles are in the range of 0.36–2.52 Bq·m2 h−1, with a mean of 1.48 Bq·m2 h−1. These measurements obtained in this study are much lower than the typical radon exhalation rate international reference value of soil, and are also within the range of the reported literatures. Meanwhile, these data are taken as input parameters of computational fluid dynamics (CFD) model for simulation comparative study. The different plane distribution of radon from the use of different brands of glazed tiles in the model residential room is simulated. The simulation results show that the distribution of radon concentration in different XY plane is un-even, and the values of radon concentrations in XY plane is decreasing with the increase of z height. Deducting the contribution of the worldwide typical outdoor radon concentration, the maximum mean radon concentration at z = 0.5 m height was found to be 6.03 Bq·m−3 in Brand ‘B.H’ which accounts for 13.40% of the worldwide geometric mean indoor radon concentration. Combined with the measurement and simulation results, it can be known that the use of glazed tiles is not the main source of indoor radon, but glazed tile with lower radon exhalation rate is still needed for health purpose.

Long-Term Measurements of Radon and Thoron Exhalation Rates from the Ground Using the Vertical Distributions of Their Activity Concentrations.

A long-term measurement technique of radon exhalation rate was previously developed using a passive type radon and thoron discriminative monitor and a ventilated type accumulation chamber. In the present study, this technique was applied to evaluate the thoron exhalation rate as well, and long-term measurements of radon and thoron exhalation rates were conducted for four years in Gifu Prefecture. The ventilated type accumulation chamber (0.8 × 0.8 × 1.0 m3) with an open bottom was embedded 15 cm into the ground. The vertical distributions of radon and thoron activity concentrations from the ground were obtained using passive type radon-thoron discriminative monitors (RADUETs). The RADUETs were placed at 1, 3, 10, 30, and 80 cm above the ground inside the accumulation chamber. The measurements were conducted from autumn 2014 to autumn 2018. These long-term results were found to be in good agreement with the values obtained by another methodology. The radon exhalation rates from the ground showed a clearly seasonal variation. Similar to findings of previous studies, radon exhalation rates from summer to autumn were relatively higher than those from winter to spring. In contrast, thoron exhalation rates were not found to show seasonal variation.

Analysis on the influence of opening and closing of ventilation tunnel on radon concentration distribution

Meteorological ventilation conditions affect easily on radon concentration in granite tunnel. In this paper, the variation of radon concentration in the tunnel in natural and ventilation conditions is analyzed through numerical simulation method. It is found that the radon concentration in tunnel can be effectively controlled by closing the tunnel entrance under the condition of pressurized ventilation.

Natural 222Rn as a tracer of mixing and volatilization in a shallow aquifer during a CO2 injection experiment

AbstractThis study aims to evaluate the application of 222Rn in groundwater as a tracer for monitoring CO2 plume migration in a shallow groundwater system, which is important to detect potential CO2 leakage in the carbon capture and storage (CCS) project. For this research, an artificial CO2‐infused water injection experiment was performed in a shallow aquifer by monitoring hydrogeochemical parameters, including 222Rn. Radon in groundwater can be a useful tracer because of its sensitivity to sudden changes in subsurface environment. To monitor the CO2 plume migration, the data were analysed based on (a) the influence of mixing processes on the distribution of 222Rn induced by the artificial injection experiment and (b) the influence of a carrier gas role by CO2 on the variation of 222Rn. The spatio‐temporal distributions of radon concentrations were successfully explained in association with horizontal and vertical mixing processes by the CO2‐infused water injection. Additionally, the mixing ratios of each monitoring well were calculated, quantitatively confirming the influence of these mixing processes on the distribution of radon concentrations. Moreover, one monitoring well showed a high positive relationship between 222Rn and Total dissolved inorganic carbon (TIC) by the carrier gas effect of CO2 through volatilization from the CO2 plume. It indicated the applicability of 222Rn as a sensitive tracer to directly monitor CO2 leakage. When with a little effect of carrier gas, natural 222Rn in groundwater can be used to compute mixing ratio of CO2‐infused water indicative of CO2 migration pathways. CO2 carrier gas effect can possibly increase 222Rn concentration in groundwater and, if fully verified with more field tests, will pose a great potential to be used as a natural tracer for CO2.

RADON MEASUREMENTS IN BIG BUILDINGS: PILOT STUDY IN RUSSIA.

Detailed analysis of indoor radon concentration distribution by floors was conducted in four children institutions, one office building and two residential houses in Russian cities to develop approaches to draw up a program of radon survey for big buildings. Higher variability of radon concentration was found in high geogenic radon potential (GRP) area when the soil is the main source of radon. No essential dependence of radon concentration on the floor in high-rise buildings was found in low GRP area. The number of required radon measurements is estimated using obtained characteristics of radon variability.