Radon Exposure Research Articles

Confined Spaces in Buildings with High Indoor Radon Concentration: A Case Study Analysis with the Application of Constructive Remediation Measures

Radon is an increasingly common concern, mainly when it is found indoors exposing the users of the space to radiation. As a gas, radon is an element produced due to uranium decay; it emanates naturally from soil and is considered by the World Health Organization as the second most common cause of lung cancer. Several methodologies are available for mitigating the indoor radon concentration, with distinct improvements and efficiencies that need to be proved with on-site testing. The case study here presented analyzes the effect of applying a barrier membrane, covering the pavement of a ground floor room located in a historic building with a high occupancy rate, on an abnormal radon concentration evidenced by experimental data. After the barrier membrane installation, a new long-term monitoring campaign (3 months) was carried out to assess indoor radon concentration. The obtained results showed that the barrier membrane lowered the indoor radon concentration by 90%. However, the radon exposure level remained higher than the recommended level to enable safe occupation and the regular use of space. Nevertheless, as the reduction in the radon concentration was very significant by the adoption of a barrier membrane, the combination of this technical solution with other mitigation methodologies, namely including the adoption of mechanical ventilation procedures, can become a very efficient solution for radon remediation, reducing the number of air changes per hour (ACH) from 30–60 to 4–6.

Chronic Home Radon Exposure Is Associated with Higher Inflammatory Biomarker Concentrations in Children and Adolescents.

Children are particularly vulnerable to the deleterious impacts of toxic environmental exposures, though the effects of some rather ubiquitous toxins have yet to be characterized in youths. One such toxin, radon gas, is known to accumulate to hazardous levels in homes, and has been linked with the incidence of lung cancer in aging adults. However, the degree to which chronic home radon exposure may impact risk for health problems earlier in life is unknown. Herein, we explored the degree to which chronic home radon exposure relates to biomarkers of low-grade inflammation in 68 youths ages 6- to 14 years old residing in an area of the United States prone to high home radon concentrations. Parents completed a home radon test kit, and youths provided a saliva sample to assess concentrations of five biomarkers. Using a multiple regression approach, we found that greater radon exposure was specifically associated with higher levels of C-reactive protein (β = 0.31, p = 0.007) and interleukin-1β (β = 0.33, p = 0.016). The data suggested specificity in associations between chronic home radon exposure and different biomarkers of inflammatory activity and highlight a pathway which may confer risk for future mental and physical health maladies.

Human Health Impacts of Residential Radon Exposure: Updated Systematic Review and Meta-Analysis of Case-Control Studies.

This study investigated the impact of residential radon exposure on human cancers (i.e., lung cancer and childhood leukemia) through a systematic review and meta-analysis of case−control studies. A total of 9724 articles obtained from electronic databases were assessed; however, only 55 case−control studies were eligible after manually screening and eliminating unnecessary studies. The causal associations were addressed by determining the meta-analysis’s estimated size effects (i.e., ORs/RRs) of the meta-analysis. Residential radon was revealed to significantly increase the incidence of lung cancer and childhood leukemia with pooled ORs of 1.38 [1.19; 1.60] (I2 = 90%; p < 0.00001) and 1.43 [1.19; 1.72] (I2 = 0% and p = 0.51), respectively. In addition, subgroup analyses were performed to reduce the heterogeneity of the initial meta-analyses. The results provided strong evidence that inhaling radon in the indoor environments is closely associated with the development of lung cancer and childhood leukemia in patients living in Europe and areas with high radon levels (≥100 Bq/m3).

High Indoor Radon Case Study: Influence of Meteorological Parameters and Indication of Radon Prone Area

Indoor radon and meteorological parameters (temperature, humidity, pressure, precipitation, indoor dew point, wind direction, wind speed and heat index) were simultaneously monitored in an old residential house in a radon suspected area. Measurements were performed during the period from winter to summer (13 February 2021–15 August 2021). Indoor radon concentrations were measured with detectors, Airthings Corentium Home (alpha spectrometry method), and meteorological parameters were continuously monitored by the meteorological station WTH600–E (wireless weather station). The influence of geological characteristics in the study area was analyzed, as well as some observed variations and correlations with indoor/outdoor meteorological parameters. The results indicated that indoor radon levels are higher in the spring/summer season than in the winter season. Diurnal radon concentrations varied during measuring period from 303–1708 Bq/m3 (average 949 Bq/m3) and 427–1852 Bq/m3 (average 1116 Bq/m3) for the living room and bedroom, respectively. Indoor radon concentrations correlated with: outdoor/indoor temperature, indoor humidity (r = 0.45, r = 0.40, r = 0.32, r = 0.56, respectively); indoor dew point (r = 0.53); outdoor barometric pressure (r = −0.26); there were no clear correlation with precipitation and outdoor humidity. The health risk due to long-term, high radon exposure was assessed through the calculated inhalation dose.

Radon exposure and risk of neurodegenerative diseases among male miners in Ontario, Canada: A cohort study.

Environmental radon has been examined as a risk factor for neurodegenerative diseases in a small number of previous studies, but the findings have been inconsistent. This study aims to investigate the association between occupational radon exposure and neurodegenerative disease in a cohort of male miners with work experience in multiple ore types in Ontario, Canada. Radon exposure (1915-1988) was assessed using two job-exposure matrices (JEM) constructed from using historical records for 34,536 Ontario male miners. Neurodegenerative outcomes were ascertained between 1992 and 2018. Poisson regression models were used to estimate incidence rate ratios (RR) and 95% confidence intervals (CI) between cumulative radon exposure in working level months (WLM) and each neurodegenerative outcome. Levels of cumulative radon exposure showed variability among cohort members with a mean of 7.5 WLM (standard deviation 24.4). Miners in uranium mines or underground jobs had higher levels and more variability in exposure than workers in non-uranium work or surface jobs. Compared to the reference group (radon < 1 WLM), increased rates of Alzheimer's (RR 1.23, 95% CI 1.05-1.45) and Parkinson's disease (RR 1.43, 95% CI 1.08-1.89) were observed among workers with >1-5 WLM and >5-10 WLM, respectively, but not among higher exposed workers (>10 WLM). This study did not observe a positive monotonic dose-response relationship between cumulative radon exposure and Alzheimer's or Parkinson's disease in Ontario mining workers. There was no association observed with motor neuron disease.

Characterizing occupational radon exposure greater than 100Bq/m3 in a highly exposed country.

Radon is an established lung carcinogen concentrating in indoor environments with importance for many workers worldwide. However, a systematic assessment of radon levels faced by all workers, not just those with direct uranium or radon exposure, has not previously been completed. The objective of this study was to estimate the prevalence of workers exposed to radon, and the level of exposure (> 100-200Bq/m3, 200-400Bq/m3, 400-800Bq/m3, and > 800Bq/m3) in a highly exposed country (Canada). Exposures among underground workers were assessed using the CAREX Canada approach. Radon concentrations in indoor workplaces, obtained from two Canadian surveys, were modelled using lognormal distributions. Distributions were then applied to the susceptible indoor worker population to yield the number of exposed workers, by occupation, industry, province, and sex. In total, an estimated 603,000 out of Canada's 18,268,120 workers are exposed to radon in Canada. An estimated52% of exposed workers are women, even though they comprise only 48% of the labour force. The majority (68%) are exposed at a level of > 100-200Bq/m3. Workers are primarily exposed in educational services, professional, scientific and technical services, and health care and social assistance, but workers in mining, quarrying, and oil and gas extraction have the largest number of exposed workers at high levels (> 800Bq/m3). Overall, a significant number of workers are exposed to radon, many of whom are not adequately protected by existing guidelines. Radon surveys across multiple industries and occupations are needed to better characterize occupational exposure. These results can be used to identify exposed workers, and to support lung cancer prevention programs within these groups.

Construction and case study of a novel lung cancer risk index

PurposeThis study constructs a lung cancer risk index (LCRI) that incorporates many modifiable risk factors using an easily reproducible and adaptable method that relies on publicly available data.MethodsWe used meta-analysis followed by Analytic Hierarchy Process (AHP) to generate a lung cancer risk index (LCRI) that incorporates seven modifiable risk factors (active smoking, indoor air pollution, occupational exposure, alcohol consumption, secondhand smoke exposure, outdoor air pollution, and radon exposure) for lung cancer. Using county-level population data, we then performed a case study in which we tailored the LCRI for use in the state of Illinois (LCRIIL).ResultsFor both the LCRI and the LCRIIL, active smoking had the highest weights (46.1% and 70%, respectively), whereas radon had the lowest weights (3.0% and 5.7%, respectively). The weights for alcohol consumption were 7.8% and 14.7% for the LCRI and the LCRIIL, respectively, and were 3.8% and 0.95% for outdoor air pollution. Three variables were only included in the LCRI: indoor air pollution (18.5%), occupational exposure (13.2%), and secondhand smoke exposure (7.6%). The Consistency Ratio (CR) was well below the 0.1 cut point. The LCRIIL was moderate though significantly correlated with age-adjusted lung cancer incidence (r = 0.449, P < 0.05) and mortality rates (r = 0.495, P < 0.05).ConclusionThis study presents an index that incorporates multiple modifiable risk factors for lung cancer into one composite score. Since the LCRI allows data comprising the composite score to vary based on the location of interest, this measurement tool can be used for any geographic location where population-based data for individual risk factors exist. Researchers, policymakers, and public health professionals may utilize this framework to determine areas that are most in need of lung cancer-related interventions and resources.

Analysis and asymptotic theory for nested case-control designs under highly stratified proportional hazards models.

Nested case-control sampled event time data under a highly stratified proportional hazards model, in which the number of strata increases proportional to sample size, is described and analyzed. The data can be characterized as stratified sampling from the event time risk sets and the analysis approach of Borgan et al.(Ann Stat 23:1749-1778, 1995) is adapted to accommodate both the stratification and case-control sampling from the stratified risk sets. Conditions for the consistency and asymptotic normality of the maximum partial likelihood estimator are provided and the results are used to compare the efficiency of the stratified analysis to an unstratified analysis when the baseline hazards can be semi-parametrically modeled in two special cases. Using the stratified sampling representation of the stratified analysis, methods for absolute risk estimation described by Borgan et al.(1995) for nested case-control data are used to develop methods for absolute risk estimation under the stratified model. The methods are illustrated by a year of birth stratified analysis of radon exposure and lung cancer mortality in a cohort of uranium miners from the Colorado Plateau.

Numerical analysis for the optimization of multi-parameters stratum ventilation and the effect on radon dispersion

To reduce hazards due to the radon dispersion on occupants, careful consideration of multi-parameters of stratum ventilation is necessary, including air supply velocity, temperature, angle and air outlet position. In this study, the radon dispersion in a typical office with stratum ventilation was evaluated based on experimental measurements and computational fluid dynamics (CFD) modelling. Besides, the ventilation performance of each scheme was evaluated by using a technique of order preference by similarity to the ideal solution (TOPSIS) method. Results showed that the mentioned factors and their interactions could pose important impacts on the indoor environment. Combining with TOPSIS, the optimal operation of the stratum ventilation was determined. Compared with the worst ventilation scheme, the ventilation effectiveness was increased by 77.4%, the air distribution performance index (ADPI) was increased by 38.1% and the radon radiological effective dose rate was reduced by 63.4%. The findings may form an important mitigation control strategy to effectively minimize radioactive exposure in indoor environments. • Operation of stratum ventilation for cooling and reducing radon in a typical office is optimized. • Parameter impact on stratum ventilation performance for cooling is analyzed. • Compared with the worst ventilation scheme, the maximum ventilation effectiveness was increased by 77.4%, the air distribution performance index (ADPI) was increased by 38.1% and the annual effective dose of radon exposure was reduced by 63.4%.

Radon Exposure in the Underground Tourist Route-Historic Silver Mine in Tarnowskie Góry, Poland.

An assessment of the exposure of workers and tourists to radon in the underground tourist route of the Historic Silver Mine in Tarnowskie Góry was carried out. The study was conducted over a one-year period to capture seasonal variations in radon concentrations. CR-39 track detectors were used to measure radon concentrations, which were exposed in the mine during the following periods: 9 February 2021-19 May 2021, 19 May 2021-26 August 2021, 26 August 2021-25 November 2021 and 25 November 2021-3 March 2022. The annual average radon concentration along the tourist route was 1021 Bq m-3. The highest measured concentration was 2280 Bq m-3 and the lowest concentration was 80 Bq m-3. Based on the measured concentrations, effective doses were calculated, assuming that employees spend 1350 h a year in underground areas and that the time of visiting the mine by tourists is ca. 1 h. The average annual effective dose a worker would receive is approximately 2.5 mSv, and a tourist below 2 μSv. The dose limit expressed as the annual effective dose is 1 mSv for members of the general public and 20 mSv for occupational exposure.

MODELING and justification of indoor radon prevention and remediation measures in multi-storey apartment buildings

In multi-storey buildings, Ra-226 in building materials is the main source of radon entry. Under low air exchange rate (e.g. in energy efficient buildings), radon concentration may exceed reference levels used for radiation protection purposes. Prevention and remediation measures of protection against indoor radon in situation when building materials are the main source of radon entry requires further development. The aim of this work is to evaluate the effectiveness of various radon prevention and mitigation measures in multi-storey buildings under different climatic conditions. On the basis of a dynamic model of indoor radon entry and removing, the following measures were simulated: control over of Ra-226 content in building materials, increasing uncontrolled air infiltration, extending the duration of controlled ventilation, equipping the building with mechanical ventilation, increasing the air exchange rate in non-living premises of the building, and reducing air exchange between living rooms and non-livings premises. The costs of energy for heating associated with different radon prevention and remediation measures were estimated. The conclusion about the potential effectiveness of various measures was drawn by achievement of optimized level of radiation protection, degree of reduction in the radon exposure risk, and cost of heating.

Lung cancer incidence attributable to residential radon exposure in Finland

This study aimed to estimate (1) the number of avoidable lung cancer cases attributable to residential radon in Finland in 2017, separately by age, sex, dwelling type and smoking status, (2) the impact of residential radon alone and the joint effect of residential radon and smoking on the number of lung cancers and (3) the potential decrease in the number of radon-attributable lung cancers if radon concentrations exceeding specified action levels (100, 200 and 300 Bq m−3) would have been mitigated to those levels. Population-based surveys of radon concentrations and smoking patterns were used. Observed radon levels were contrasted with 25 Bq m−3 representing a realistic minimum level of exposure. Lung cancer risk estimates for radon and smoking were derived from literature. Lastly, the uncertainty due to the estimation of exposure and risk was quantified using a computationally derived uncertainty interval. At least 3% and at most 8% of all lung cancers were estimated as being attributable to residential radon. For small cell carcinoma, the proportion of cases attributable to radon was 8–13%. Among smokers, the majority of the radon-related cases were attributable to the joint effect of radon and smoking. Reduction of radon exposure to 100 Bq m−3 action level would eliminate approximately 30% of radon-attributable cases. Estimates were low compared with the literature, given the (relatively high) radon levels in Finland. This was mainly due to the lower radon levels and higher smoking prevalence in flats than in houses and a more realistic point of comparison, factors which have been ignored in previous studies. The results can guide actions in radon protection and in prevention of lung cancers.

Investigation of Radon in Groundwater and the Corresponding Human-Health Risk Assessment in Northeastern Saudi Arabia

Radon is one of the most common human exposures as a natural radiation source and can cause lung, colon, and stomach cancer. In this study, groundwater from different wells was collected from the northeastern part of Saudi Arabia. The radon concentration was estimated using an electronic portable radon detector RAD7 with a big-bottle system. The annual effective dose of radon exposure by the ingestion and inhalation of water is calculated using the radon concentration for different age groups to assess the health risk of radon exposure. The calculated annual effective doses are then compared with the international risk limit standard as international organizations direct. The estimated radon concentration for groundwater samples in the searched area was between 0.03 and 3.20 Bq/L, with an average value of 1.16 Bq/L. These estimated values are far below the safety limit set by international organizations. The annual effective dose of radon exposure for infants, children and adults ranged from 0.05 to 16.24 μSv/y, with a mean value of 5.89 μSv/y. The health risk assessed by radon exposure for infants, children and adults was found to be in the safe limit recommended by international organizations.

Indoor radon concentration measurements in workplaces and their impact on health risk assessment

Radon is the main source of exposure to ionizing radiation for the general population. In Italy, very little has been investigated to determine occupational radon exposure in workers. In this study, radon concentrations of various workplaces type were measured for 1 year using SSNTD CR-39. Q–Q plot and Shapiro–Wilks statistical test showed that radon concentrations are not log-normally distributed. The geometric mean of radon concentration was found to be 97 Bq/m3 with a geometric standard deviation of 3. The mean effective dose to workers has been calculated and found to be 1.4 mSv/y. Finally, for estimation of cancer risks, the lifetime risk and lung cancer cases per year per million have been calculated.

A prospective cohort analysis of residential radon and UV exposures and malignant melanoma mortality in the Swiss population.

Radon is a radioactive noble gas naturally found in the earth crust that can accumulate in buildings. In addition to lung cancer, alpha particles emitted by radon may contribute to the risk of skin cancer. We evaluated the association between residential radon exposure and skin cancer mortality, over a fifteen year period, taking residential ultra-violet (UV) exposure into account. We included 4.9 million adults from the Swiss National Cohort. Hazard ratios for melanoma mortality were estimated using Cox proportional hazard models (20+ years old; follow-up 2001-2015). Long-term modelled residential radon and ambient UV exposures were assigned at baseline, and included together in the Cox models. With age as a time scale, models were adjusted for calendar time, sex, marital status, education, mother tongue, socioeconomic position, and occupational environment with potential for UV exposure. Age specific hazard ratios were derived. Effect modification, sensitivity analyses and the shape of the exposure response, as well as secondary analysis using other outcome definitions, were investigated. During follow-up (average of 13.6 years), 3,979 melanoma deaths were observed. Associations declined with age, with an adjusted hazard ratio per 100 Bq/m3 radon at age 60 of 1.10 (95% CI: 0.99, 1.23). The dose-response showed an approximate linear trend between the minimum and mean radon exposure of 75 Bq/m3. Having outdoor occupation significantly increased the risk of melanoma mortality associated with UV exposure compared to indoor jobs. Analysis restricted to the last five years of follow-up showed similar results compared to the main analysis. Similar associations were found for mortality from melanoma and non-melanoma skin cancer combined. With double the follow-up time, this study confirmed the previously observed association between residential radon exposure and melanoma and non-melanoma skin cancer mortality in Switzerland. Accumulation of radon indoors is preventable and of public health importance.

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.

Lung cancer as adverse health effect by indoor radon exposure in China from 2000 to 2020: A systematic review and meta-analysis.

Indoor radon exposure is thought to be associated with adverse health effect as lung cancer. Lung cancer incidences in China have been the highest worldwide during the past two decades. It is important to quantitively address indoor radon exposure and its health effect, especially in countries like China. In this paper, we have conducted a meta-analysis based on indoor radon and its health effect studies from a systematic review between 2000 and 2020. A total of 8 studies were included for lung cancer. We found that the relative risk (RR) was 1.01 (95% CI: 1.01-1.02) per 10Bq/m3 increase of indoor radon for lung cancer in China. The subgroup analysis found no significant difference between the conclusions from the studies from China and other regions. The health effect of indoor radon exposure is relatively consistent for the low-exposure and high-exposure groups in the subgroup analysis. With a better understanding of exposure level of indoor radon, the outcomes and conclusions of this study will provide supports for next phase of researches on estimation of environmental burden of disease by indoor radon exposures in countries like China.

Radon levels and indoor air quality after application of thermal retrofit measures-a case study.

This study was conducted to evaluate the influence of thermal retrofit on radon levels in workrooms, and to determine whether the radon concentration in the building changes after the application of retrofit measures. In the first survey, digital Airthings Corentium Home radon detector was used for 1-month radon measurements during the heating season 2018/19. The daily averaged radon concentrations varied from 37 to 573Bq/m3 for 10 selected workrooms, while hourly averaged radon measurements showed extreme variations from 6 to 1603Bq/m3 due to radon fluctuations. In second survey, passive radon technique based on charcoal canister test kit was conducted in all basement workrooms in spring 2021. The averaged radon concentrations grouped according to flooring type in workrooms were 327Bq/m3 for parquet, 227Bq/m3 for ceramic tiles, 146Bq/m3 for vinyl flooring and 71Bq/m3 for laminate. Besides thermal insulation and airtight windows, noticeable differences in indoor radon concentration within the renovated building are primarily caused by different types of flooring. It includes various types of insulation from the ground/concrete slab: laminate, parquet (wood blocks), vinyl flooring, and ceramic tiles. Detailed analysis point out that laminate is more efficient way for radon protection than other types of flooring. An efficient ventilation system should be installed to avoid increasing occupational radon exposure and to provide healthy and comfortable indoor environment.

Radon in groundwater sources of Bosso Community in North Central Nigeria and concomitant doses to the public

Realizing the probable health hazards from radon exposure, potable groundwater samples (hand-dug wells and boreholes) in the Bosso community of North Central Nigeria were collected and assayed for radon concentration. Durridge RAD-7 detector together with RAD-H2O accessories was employed in this study. The committed effective dose to different ICRP age groups was computed using various parameters including the annual water consumption characteristics. The mean 222Rn activity in water samples from hand-dug wells and boreholes were 9.81 ± 1.85 Bq/L and 24.78 ± 2.48 Bq/L respectively. The average whole-body committed effective dose due to ingestion and inhalation of waterborne radon from the two groundwater sources are 0.026 mSv/y and 0.067 mSv/y for hand-dug wells and boreholes respectively, which are below the safety threshold of 0.1 mSv/y recommended by the European Union. The results showed that there is no significant radiation threat to public health from inhalation and ingestion of waterborne radon within the community.

INDOOR RADON (222RN) MEASUREMENTS AND ESTIMATION OF ANNUAL EFFECTIVE DOSE IN MVANGAN LOCALITY, SOUTH CAMEROON.

The present work was aimed at measuring indoor radon activity concentrations in dwellings in Mvangan locality, South Cameroon, in order to assess the extent of measures that may be necessary for controlling public indoor radon exposure in this area. Measurements were carried out using passive solid-state nuclear track detectors (RADONAVA Inc., RadTrak2, Sweden) following ISO 11665-4 standard. Radon concentration ranged between 36±20 and 150±30Bqm-3 with arithmetic and geometric means values of 64±25 and 60±1Bqm-3, respectively. These mean values were greater than worldwide values presented by United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), which are, respectively, 40 and 30Bqm-3. 96% of dwellings that have radon concentrations below the World Health Organization (WHO) reference level of 100Bqm-3, whereas 4% of dwellings have radon concentrations higher than this level but lower than 300Bqm-3, the International Commission on Radiological Protection (ICRP) reference level. Annual effective doses due to indoor radon ranged between 0.7 and 2.8mSv y-1 with an arithmetic mean value of 1.2±0.5mSv y-1. These values were below the lower limit of the ICRP-recommended action level interval 3-10mSv y-1. It has been observed that annual effective dose received by residents in cement bricks dwellings were not significantly different (P-value=0.565) than those received by residents in mud dwellings in Mvangan locality. The mean number of persons expected to be diagnosed with or die from cancer (solid cancers and leukemia) were 162±48 (61±25 for males and 101±41 for females) and 82±24 (33±13 for males and 49±20 for females), respectively. The results obtained in this study prove that the populations of Mvangan locality are exposed to a relatively low potential risk of cancer incidence and mortality.