Radon Survey Research Articles

A representative national indoor radon survey in Germany

A representative national indoor radon survey in Germany

Utilization of radiometric data for mapping primary and secondary sources of gamma radiation and radon/thoron release potentials in Ireland.

This paper presents a novel approach to predict and map radon and thoron levels. We developed separate radon and thoron prediction maps for Ireland and introduced a system for producing high-resolution 3D radiation maps which may be used for planning purposes in residential areas, recycling and demolishing waste depots, and quarries of building and construction material. Additionally, we highlight the critical need to monitor thoron alongside radon in indoor surveys, as thoron's shorter half-life and higher energy levels may pose a greater health risk. We utilized Tellus radiometric survey data and indoor radon measurement records to investigate the spatial correlation between elevated indoor radon activity and anomalies in radioelement concentrations. We also estimated the degree of thoron interference in indoor radon surveys conducted in Ireland using CR-39 detectors. Field and laboratory surveys were performed to produce high-resolution radiation maps for four Irish quarries and estimate the radon and thoron potential of these quarries. Our initial findings suggest that thoron may be the primary health issue in some parts of Ireland, surpassing radon. For example, our map shows that the expected thoron potential in county Donegal is significantly higher than that for radon. Our radon and thoron exhalation tests on building material samples from four random quarries confirm this. We also estimate that over 20% of the elevated indoor radon activity recorded by the EPA using CR-39 detectors may be attributed to thoron-related sources. This study contributes to a better understanding of the prevalence and impact of radon and thoron in Ireland, helping to determine the main radiological health issue related to indoor air quality in the country. Thoron's impact on indoor air quality and health has been understudied in Ireland, necessitating more comprehensive studies and monitoring programs to accurately assess the prevalence and impact of both radon and thoron.

Development of a High-Resolution Indoor Radon Map Using a New Machine Learning-Based Probabilistic Model and German Radon Survey Data.

Radon is a carcinogenic, radioactive gas that can accumulate indoors and is undetected by human senses. Therefore, accurate knowledge of indoor radon concentration is crucial for assessing radon-related health effects or identifying radon-prone areas. Indoor radon concentration at the national scale is usually estimated on the basis of extensive measurement campaigns. However, characteristics of the sampled households often differ from the characteristics of the target population owing to the large number of relevant factors that control the indoor radon concentration, such as the availability of geogenic radon or floor level. Furthermore, the sample size usually does not allow estimation with high spatial resolution. We propose a model-based approach that allows a more realistic estimation of indoor radon distribution with a higher spatial resolution than a purely data-based approach. A multistage modeling approach was used by applying a quantile regression forest that uses environmental and building data as predictors to estimate the probability distribution function of indoor radon for each floor level of each residential building in Germany. Based on the estimated probability distribution function, a probabilistic Monte Carlo sampling technique was applied, enabling the combination and population weighting of floor-level predictions. In this way, the uncertainty of the individual predictions is effectively propagated into the estimate of variability at the aggregated level. The results show an approximate lognormal distribution of indoor radon in dwellings in Germany with an arithmetic mean of , a geometric mean of , and a 95th percentile of . The exceedance probabilities for 100 and are 12.5% (10.5 million people affected) and 2.2% (1.9 million people affected), respectively. In large cities, individual indoor radon concentration is generally estimated to be lower than in rural areas, which is due to the different distribution of the population on floor levels. The advantages of our approach are that is yields a) an accurate estimation of indoor radon concentration even if the survey is not fully representative with respect to floor level and radon concentration in soil, and b) an estimate of the indoor radon distribution with a much higher spatial resolution than basic descriptive statistics. https://doi.org/10.1289/EHP14171.

Evaluating radon concentration and temporal correction factors in residential and workplace buildings: A comparison of passive and active methods

Effective mitigation of the health impacts of radon exposure begins with accurate measurement of this environmental contaminant. Typically, radon surveys require measurements over a period of several months. This process involves the application of temporal correction factors (TCF). Disparities in indoor radon concentration (IRC) are evident across building types. While the integrated technique has traditionally been considered the most reliable for measuring IRC, the active method is becoming more prevalent due to the availability of commercial radon measurement instruments. The aim of this study is to compare IRC using passive (CR-39) and active (ICA device) methods across 69 indoor spaces, including 35 workplaces and 34 residential buildings. The investigation was conducted over a span of one year and included 966 CR-39 detectors that were replaced every 3 and 6 months, respectively, to assess seasonal fluctuations and facilitate the computation of TCF. Statistically significant differences in IRC were observed between residential and workplace buildings (p < 0.001). Among workplaces, educational and research institutions showed the highest average IRC (166 Bq/m3), while hospitals exhibited the lowest (25 Bq/m3). Significant differences in TCF were found between the two measurement methods (p < 0.05), making TCF specific to the passive method inapplicable to active method. Moreover, distinctions between workplace and residential buildings, including the presence of air conditioning units and differing occupancy patterns, lead to substantial differences in both IRC (p < 0.001) and TCF. The assessment of radon exposure based on room occupancy duration revealed substantial variations: workplaces showed lower actual exposure (62 Bq/m3 vs. 75 Bq/m3, p < 0.001), while residential settings, particularly at night, displayed higher exposure (278 Bq/m3 vs. 245 Bq/m3, p = 0.02) than integrated measurements suggest. Continuous monitoring systems offer critical insights into true radon exposure levels.

Analysis of data on levels of public exposure to natural sources of radiation in the Ivanovo region

The paper presents the results of analysis of the Ivanovo Regional databank of radiation doses to the pub-lic from exposure to natural and technologically enhanced radiation background for 2008–2022. Despite the fact that the average individual annual effective dose of public exposure due to natural sources of radiation in the Ivanovo region calculated for the whole 15-year period (4.63 mSv/year) does not qualify as increased (i.e. does not exceed the level of 5 mSv/year), in some years of the period under review the average dose repeatedly exceeded this level, reaching 7.50 mSv/year. The analysis of the structure of the doses of public exposure due to natural sources of radiation in the Ivanovo region showed that the contribution of the dose from internal exposure to radon, thoron and progenies according to measurement results from 2008–2022 ranged from 65.98 to 81.47%. The paper provides examples of buildings of different types in settlements of the Ivanovo region, in which the indoor radon isotopes equilibrium equivalent concentrations are more than 1.5 times higher than the established action level for existing dwellings and public buildings (200 Bq/m3). Despite the significant amount of measurement data in the Regional databank, it is necessary to obtain additional information on the indoor radon levels in existing wooden and other low-rise dwellings and public buildings in the most radon-prone areas of the region. For this purpose, a radon survey is planned for 2024-2026 in the cities of Ivanovo and Kohma, Privolzhsky, Gavrilovo-Posadsky, Teykovsky and Zavolzhsky districts of the Ivanovo region within the framework of a joint project of Saint-Petersburg Research Institute of Radiation Hygiene after Professor P.V. Ramzaev, the Directorate of the Federal Service for Surveillance on Consumer Rights Protection and Human Wellbeing in the Ivanovo region, and the Center of Hygiene and Epidemiology in the Ivanovo region.

Indoor radon monitoring in Zázrivá

Indoor radon survey in Zázrivá was conducted within the framework of the project “Multidisciplinary research of geophysical and structural parameters, and environmental impacts of faults of the Western Carpathians”. Monitoring was carried out in selected houses and kindergarten using RamaRn detectors. Annual average of indoor radon varied between 45 and 260 Bq/m3, with median of 90 Bq/m3. Seasonal variation with minimum in summer was observed in the majority of monitored rooms. Radon concentration higher than 200 Bq/m3 was measured only in rooms with direct contact with the subsoil. A possible relation between the position of a monitored building close to an assumed fault line and elevated indoor radon levels was not proven.

Public exposure in the Orenburg region due to natural sources of ionizing radiation. Part 3: Approaches to radon survey planning

A comprehensive radiation survey of settlements in six districts of the eastern part of the Orenburg region in terms of exposure to natural sources of ionizing radiation, carried out in 2019, revealed numerous exceedances of the hygienic norm (action level) for indoor radon concentration in residential and public buildings. It was found that among other studied factors, exhalation of radon from the ground under the buildings is the main source of high levels of public exposure. Due to the lack of funding for the continuation of the survey in 2020, specialists of St. Petersburg Research Institute of Radiation Hygiene after Professor P.V. Ramzaev, Directorate of Rospotrebnadzor in the Orenburg region and the Center of Hygiene and Epidemiology in the Orenburg region needed to develop new approaches to survey planning. These new approaches should provide maximum amount of measurement information necessary to ensure radiation safety of the region’s population, with minimal financial investments and labor costs. Indoor radon concentration in residential and public buildings was undoubtedly chosen as the studied factor, and the integrated measurement method using SSNTDs was chosen as the most suitable method for the objectives of the survey due to its scalability and ease of detectors deployment. Since exposure to radon and its progeny is the second leading cause of lung cancer after smoking, the selection of priority districts of the region for the radon survey was based on average standardized trachea, bronchi, and lung cancer morbidity rates in the districts of the Orenburg region for 2009-2018. The survey conducted in 2020-2023 revealed exceedances of the hygienic norm (action level) for indoor radon concentration in five of seven surveyed districts. By 2025 it is planned to conduct radon surveys in three more districts of the Orenburg region with increased respiratory systems cancer morbidity rates.

Optimal Conformal Prediction for Small Areas

Abstract Existing methods for small-area data involve a trade-off between maintaining area-level frequentist coverage rates and improving precision via the incorporation of indirect information. In this article, we develop an area-level prediction region procedure that mitigates this trade-off. The method takes a conformal prediction approach in which the conformity measure is the posterior predictive density of a working model that incorporates indirect information. The resulting prediction region has guaranteed within-area frequentist coverage regardless of the working model, and, if the working model assumptions are accurate, the region has smaller expected volume compared to other regions with the same coverage rate. For a normal working model, we prove such a prediction region is an interval and construct a straightforward algorithm to obtain its endpoints. We illustrate the performance of our method through simulation studies and an application to EPA radon survey data.

Relationship between Ra-226 activity concentration in building materials and indoor radon concentration: An example of Russian high-rise residential buildings

The worldwide trend toward the construction of high-rise buildings with high energy efficiency highlights the role of building materials as a source of indoor radon in the modern urban environment. The aim of the study is to analyze the relationship between the Ra-226 activity concentration in building materials and indoor radon concentration using the example of multi-story buildings in Ekaterinburg. Measurements of the activity concentration of natural radionuclides in building materials were carried out using a new non-destructive method. A radon survey conducted early provided the data on indoor radon concentrations in the same apartments. The obtained Ra-226 activity concentrations in building materials in high-rise buildings were found to be relatively low, ranging from 9.1 to 51 Bq/kg. The typical radon entry rate by diffusion from building materials for modern Russian multi-story buildings can be accepted as equal to 0.5 Bq/(m3∙h) per 1 Bq/kg of Ra-226 activity concentration. Ra-226 in building materials has been shown to be a primary source of indoor radon in modern high-rise buildings, where this factor can cause indoor radon concentrations above the reference level of 100 Bq/m3 at low air exchange rates. The activity concentration of Ra-226 in building materials should be considered a separate parameter for regulation within the national radiation protection systems.

Smoking Modifies the Association Between Radon Exposure and Incident Ischemic Stroke: The REGARDS Study.

Exposure to radon has been linked to lung cancer and other lung diseases. Although biologically plausible, research of residential radon exposure in relation to stroke risk is scarce. Study participants were from the REGARDS (Reasons for Geographic and Racial Differences in Stroke) cohort (n=30 239), which consisted of male and female non-Hispanic Black and White adults aged 45 and older. After excluding participants with baseline stroke and transient ischemic attack, and missing information on exposure and outcome of interest, the final sample size was 26 950. The primary outcome was time to the first ischemic stroke through September 30, 2020. County-level radon measures from Lawrence Berkeley National Laboratory were linked to each participant based on their geocoded residential history. We used Cox proportional hazards regression models with a time-dependent exposure to estimate hazard ratios and 95% CIs for the association. After controlling for potential confounding factors including demographic, lifestyle, clinical variables, and PM2.5, radon exposure was significantly associated with incident ischemic stroke among never-smokers (hazard ratio, 1.39 [95% CI, 1.01-1.90]) but not ever-smokers. The results were generally consistent in the sensitivity analysis when using radon measures from state/Environmental Protection Agency residential radon survey. Findings from this study suggest that the association between residential radon exposure and incidence of ischemic stroke varies by smoking status and may be prominent in never-smokers. Further studies incorporating indoor-radon measures are needed to confirm these findings.

Predicting Monthly Community-Level Radon Concentrations with Spatial Random Forest in the Northeastern and Midwestern United States.

In 1987, the United States Environmental Protection Agency recommended installing a mitigation system when the indoor concentration of radon, a well-known carcinogenic radioactive gas, is at or above 148 Bq/m3. In response, tens of millions of short-term radon measurements have been conducted in residential buildings over the past three decades either for disclosure or to initially evaluate the need for mitigation. These measurements, however, are currently underutilized to assess population radon exposure in epidemiological studies. Based on two relatively small radon surveys, Lawrence Berkeley National Laboratory developed a state-of-the-art national radon model. However, this model only provides coarse and invariant radon estimations, which limits the ability of epidemiological studies to accurately investigate the health effects of radon, particularly the effects of acute exposure. This study involved obtaining over 2.8 million historical short-term radon measurements from independent laboratories. With the use of these measurements, an innovative spatial random forest (SRF) model was developed based on geological, architectural, socioeconomical, and meteorological predictors. The model was used to estimate monthly community-level radon concentrations for ZIP Code Tabulation Areas (ZCTAs) in the northeastern and midwestern regions of the United States from 2001 to 2020. Via cross-validation, we found that our ZCTA-level predictions were highly correlated with observations. The prediction errors declined quickly as the number of radon measurements in a ZCTA increased. When ≥15 measurements existed, the mean absolute error was 24.6 Bq/m3, or 26.5% of the observed concentrations (R2 = 0.70). Our study demonstrates the potential of the large amount of historical short-term radon measurements that have been obtained to accurately estimate longitudinal ZCTA-level radon exposures at unprecedented levels of resolutions and accuracy.

Characteristics of Indoor and Soil Gas Radon, and Discussion on High Radon Potential in Urumqi, Xinjiang, NW China

Urumqi City, located in the northwest of China, is a city with a high indoor radon concentration in a nationwide indoor radon survey in China. This study focuses on the assessment of the indoor radon level and its distribution in this city. Indoor radon measurement using RAD7 and solid nuclear track detector (SSNTD), soil gas radon measured by RAD7, and the determination of the specific activity of uranium and radium in soil samples by a high pure germanium spectrometer were performed from 2021 to 2023. The results reveal a wide range of indoor radon concentrations in Urumqi, with anomalies above 400 Bq/m3 in some dwellings. The arithmetical and geometric mean values of indoor radon concentration are 80 ± 77 Bq/m3 and 58 Bq/m3, respectively. The geometric mean value of radon measured by SSNTD is 101 Bq/m3. The distribution of areas with a high indoor radon concentration is spatially consistent with deep and large active faults or overlapping and intersection zones of multiple groups of faults. It is recommended to conduct a more comprehensive investigation and research into the elevated radon potential and radioactivity associated with building materials.

The Analysis of 222Rn and 220Rn Natural Radioactivity for Local Hazard Estimation: The Case Study of Cerveteri (Central Italy).

Radon (222Rn) is the second most common cause of lung cancer after smoking. As radon poses a significant risk to human health, radon-affected areas should be identified to ensure people's awareness of risk and remediation. The primary goal of this research was to investigate the local natural radioactivity (in soils, groundwater, and indoors) because of the presence of tuff outcrops (from middle-lower Pleistocene volcanic activity) that naturally produce radioactive gas radon at Cerveteri (Rome, Central Italy). The results of the radon survey highlighted moderate (>16,000 Bq/m3) but localized anomalies in soils in correspondence with a funerary site pertaining to the Etruscan Necropolis of Cerveteri, which extends over a volcanic rock plateau. Indoor radon measurements were performed at several tuff-made dwellings, and the results showed medium-low (<200 Bq/m3) values of indoor radon except for some cases exceeding the reference level (>300 Bq/m3) recommended by the 2013/59 Euratom Directive. Although no clinical data exist regarding the health effects of thoron (220Rn) on humans, the study of 220Rn average activity concentration in the soil gas survey reveals new insights for the interpretation of radon sources that can affect dwellings, even taking into account the considerable difference in the half-lives of 222Rn and 220Rn.

Indoor Radon Survey in Aksu School and Kindergarten Located near Radioactive Waste Storage Facilities and Gold Mines in Northern Kazakhstan (Akmola Region)

Northern Kazakhstan is considered a field of uranium, gold mining, copper–molybdenum ore, and other metals. The aims of the current work were to monitor the indoor radon levels in a school and a kindergarten and to determine the levels of teacher and student exposure to radon. High radon concentrations were detected in the school on the first floor at ca. 9600 Bq/m3, on the second floor at ca. 6800 Bq/m3, on the third floor at ca. 4900 Bq/m3, and in the kindergarten, the concentration was ca. 9500 Bq/m3. The annual effective dose of the students and teachers of the school and kindergarten varied from 4 mSv/y to 9 mSv/y, which is an order of magnitude higher than the upper annual dose limit. The excess lifetime cancer risk was 14–20% for students, 31.1% for school and kindergarten staff, and 34.9% for kindergarten children. The indoor radon concentrations varied with weather conditions, and it was evident that ventilation had a significant effect on the reduction in the concentration. At these premises, positive correlations between the radon concentrations, outside temperature, and relative humidity were obtained, showing that the concentration of radon is influenced by meteorological parameters. This study will help to identify buildings where continuous monitoring is needed in order to reduce indoor radon levels.

Application of airborne geophysical survey data in a logistic regression model to improve the predictive power of geogenic radon maps. A case study in Castleisland, County Kerry, Ireland

In this study, a novel methodology was investigated to improve the spatial resolution and predictive power of geogenic radon maps. The data inputs comprise indoor radon measurements and seven geogenic factors including geological data (i.e. bedrock and Quaternary geology, aquifer type and soil permeability) and airborne geophysical parameters (i.e. magnetic field strength, gamma-ray radiation and electromagnetic resistivity). The methodology was tested in Castleisland southwest Ireland, a radon-prone area identified based on the results of previous indoor radon surveys. The developed model was capable of justifying almost 75 % of the variation in geogenic radon potential. It was found that the attributes with the greatest statistical significance were equivalent uranium content (EqU) and soil permeability. A new radon potential map was produced at a higher spatial resolution compared with the original map, which did not include geophysical parameter data. In the final step, the activity of radon in soil gas was measured at 87 sites, and the correlation between the observed soil gas radon and geophysical properties was evaluated. The results indicate that any model using only geophysical data cannot accurately predict soil radon activity and that geological information should be integrated to achieve a successful prediction model. Furthermore, we found that EqU is a better indicator for predicting indoor radon potential than the measured soil radon concentrations.

Mapping the fraction of dwellings exceeding radon level thresholds in the Lazio region, central Italy.

The risks arising from exposure to radon in buildings call for the planning of actions to reduce indoor radon levels. Maps of the fraction of dwellings above a threshold make it possible to identify areas where actions can be concentrated to optimize resources. The grid square method was applied to data collected in the radon survey carried out in the Lazio region, located in central Italy, to estimate the fractions of dwellings with radon concentrations above 100, 200and 300Bqm-3. Spatial correlation between radon measurements was used to improve the estimates. Depending on the threshold, selecting areas where >10% of dwellings are above, the territory covered varies from about 100% to about 20% of the entire region.

Indoor radon concentration in state schools of four Bulgarian districts.

Indoor radon concentrations were surveyed in 230 public schools in four Bulgarian districts for the period November/December 2019 to May/June 2020. The measurements were carried out in 2427 rooms on the basement, ground floor and first floor using the passive track detectors of the Radosys system. The estimated arithmetic and geometric means with standard deviations were 153±154 and 114Bq/m3 (geometric standard deviation (GSD)=2.08), respectively. The results are higher than those referred from the National Radon Survey in dwellings. In 9.4% of the rooms, the radon concentrations were above the reference value of 300Bq/m3. The difference between indoor radon concentrations in the districts was significant, which proves its spatial variation. The hypothesis that the applied energy efficiency measures increase indoor radon values in buildings was confirmed. The surveys demonstrated the importance of indoor radon measurements in school buildings, in order to control and reduce children's exposure.

An Innovative Method for Mitigation of Radon: A Case Study in Bangalore Area, Karnataka, India

Introduction:&#x0D; Elevated radon levels in the indoor environment in many countries that led to the realization of residential radon as being a possible public health issue in the western world. It was also hoped that in conjunction with epidemiological studies, large-scale indoor radon surveys might lead to quantitative understanding of the low dose effects of radon exposures. Earlier work for the environment of Bangalore city reveals that, the activity concentrations of 226Ra in soil varied in the range of 7.7–111.6 Bqkg-1 with a mean value of 26.2 Bqkg-1. The concentration of 232Th varied in the range 16.7–98.7 Bqkg-1 with a mean value of 53.1 Bqkg-1 and that of 40K in the range 151.8 –1424.2 Bqkg-1 with a mean value of 635.1 Bqkg-1. An attempt has been made to observe the reduction in radon concentration by deploying lamination on the walls and mosaic tiles on the floorings of the room.&#x0D; Objectives: Radon mitigation is a new approach to minimize the radioactive gases in the working environment. In view of this an attempt has been made to witness the reduction in radon concentrations due to Formica laminate on the walls and placing mosaic tiles on the flooring of the room. &#x0D; Methods: CAN technique and solid state nuclear track detectors based dosimeters are used for the observation of radon exhalation and the concentration of radon/thoron levels in a room. .&#x0D; Results: Good reduction in radon levels were observed after deploying the Formica laminate on the walls of the room and the mosaic on the floorings of the room. This is an innovative method needs to be incorporated for the reduction in higher level concentrations. &#x0D; Conclusions: Reduction in concentration is more than 50% after renovation and it may be used as an innovative approach.

Radon concentrations in the Sudwala cave, South Africa

There has been a growing interest in the effect of radon gas on humans visiting caves. A radon survey was consequently done in the Sudwala tourist cave close to Nelspruit in the eastern part of South Africa to determine the radon exposure of tourists and guides. The Sudwala cave, which evolved in karst geology, is a popular tourist destination. Twenty-eight electret ion chambers were placed in various locations throughout the cave for a period of 24 h. Radon concentrations varied between a minimum of 255 Bq/m3 and a maximum of 1822 Bq/m3 with a geometric mean of 750 Bq/m3. The radon levels were found to be relatively stable up to 600 m from the entrance, after which they sharply increased. This suggests that different processes disperse radon in the initial and deeper parts of the cave. It was concluded that this is the result of natural cave ventilation which is caused by changes in ambient barometric pressure. Despite the measured level being higher than the World Health Organization (WHO)’s mitigation level of 200 Bq/m3, the occupational exposure is quite low due to the frequency and duration of a typical cave tour and therefore poses no risk to the tourists and tour guides.

Indoor radon survey in Whitehorse, Canada, and dose assessment

Radon-222 (222Rn) and its decay products are the primary sources of a population’s exposure to background ionizing radiation. Radon decay products are the leading cause of lung cancer for non-smokers and the second leading cause of lung cancer after smoking for smokers. A community-driven long-term radon survey was completed in 232 residential homes in different subdivisions of Whitehorse, the capital of the Yukon, during the heating season from November to April in 2016–2017 and in 2017–2018. Radon concentrations were measured in living rooms and bedrooms on ground floors. The arithmetic and geometric means of indoor radon activity concentrations in different subdivisions of Whitehorse ranged from 52 ± 0.6 Bq m−3 and 37 ± 2.3 Bq m−3 in the Downtown area of Whitehorse to 993.0 ± 55.0 Bq m−3 and 726.2 ± 2.4 Bq m−3 in Wolf Creek. Underlying geology and glacial surfaces may partly explain these variations of indoor radon concentrations in subdivisions of Whitehorse. A total of 78 homes (34.0%) had radon concentrations higher than 100 Bq m−3, 47 homes (20.5%) had concentrations higher than 200 Bq m−3 and 33 homes (14.4%) had concentrations higher than 300 Bq m−3. The indoor radon contribution to the annual effective inhalation dose to residents ranged from 3.0 mSv in the Downtown area to 51.0 mSv in Wolf Creek. The estimated annual average dose to adults in Whitehorse, Yukon, is higher than the world’s average annual effective dose of 1.3 mSv due to the inhalation of indoor radon. The annual radon inhalation effective dose was assessed using radon measurements taken during winter; hence the assessed dose may be overestimated. Cost-efficient mitigation methods are available to reduce radon in existing buildings and to prevent radon entry into new buildings.