Variation Of Radon Concentration Research Articles

Modelling of the temporal indoor radon variation in Bulgaria.

In this study, temporal variations of indoor radon concentrations in Bulgaria were investigated. The radon concentrations were measured by nuclear track detectors as part of the Bulgarian National Survey, performed in the dwellings of 28 regional districts. The detectors were exposed through a year in two consecutive time periods of different lengths. For 2433 dwellings, measurements could be completed for both time periods, while for 345 dwellings they could only be completed for one of the periods. To estimate any missing radon concentrations, a temporal correction procedure was developed. This procedure, which included development of a linear correlation between the ln-transformed radon concentrations from the 9-month period [CRn(L)] and from the 3-month period [CRn(S)]. A normal distribution of the data, which is a condition for linear regression, was achieved when the ln-transformed radon concentrations were grouped by climate zone, then by regional districts, and finally by the presence/absence of a basement in the investigated building. The linear models obtained for each group showed reasonable coefficients of determination (R2 ≈ 0.50) and root mean square errors (RMSEs) of about 0.50. When these correlations were used to reconstruct radon concentrations in missing measurement periods, it turned out that the reconstructed data (for 345 dwellings) were within the 95% confidence interval of the measured data (for 2433 dwellings). The geometric means of CRn(L) and CRn(S) were 76Bq/m3 and 100Bq/m3, respectively, for 2433 dwellings, which are almost equal to those of 75Bq/m3 and 98Bq/m3, which represent the measured and reconstructed data together (for 2778 dwellings).

Radiation in different types of building, human health

Radon is a radioactive gas permanently produced in rocks, soils, building materials as an indirect decay product of uranium and thorium. According to EPA, radon is the second most frequent cause of lung cancer, after cigarette smoking.The aim of survey was to measure radon levels and ambient gamma dose rates in dwellings in various types of buildings situated on various ground and to evaluate health parameters depended on indoor radiation such as lung cancer risk and total annual effective dose rate. Moreover, we wanted to verify the possibility to predict indoor radon concentration in specific dwelling knowing types of soil, building construction, building materials and floor number.The measurements of radon concentrations were carried out using SSNTDs Kodak LR-115 which were exchanged seasonally. The ambient gamma dose rates were measured using Geiger counter.Radon concentrations in all dwellings were lower than 300 Bq m−3 (recommended by EU action level). In some dwellings during some seasons radon concentrations were above 100 Bq m−3. Prolonged exposure to indoor radon at the levels of 100 Bq m−3 causes statistically significant increase of lung cancer. The average indoor radon concentration in Wroclaw's dwellings was 46 Bq m−3. The annual risk of lung cancer was lower than 0.0005%. The total annual effective dose rates ranged from 1.36 mSv y−1 to 3.3 mSv y−1. We observed seasonal, vertical, spatial variations of radon concentrations. We did not notice significant drop of ambient gamma dose rates between the ground floor and floors 2nd to 5th as we did for radon concentrations. We noticed that indoor radon concentrations differed 4 to 6 times even among dwellings located in these same types of buildings, on these same soil types or these same floors.

Application of Gravity and Radon Studies to Delineate the Concealed Section of the Khisor Thrust

Radon concentration, a geochemical parameter of naturally occurring noble gas and potential relative gravity field variation, has been studied in the current investigations. These investigations were carried out along and in proximity to the Khisor Thrust in the Trans Indus ranges marking the southern boundary of Bannu basin in Pakistan. The studies were aimed to demark the concealed section of the thrust fault beyond termination of its surface signature. The consistent increasing pattern of radon variation while approaching the approximate location of fault and decrease while moving farther from it suggests the existence of a fault to the subsurface, which should be verified through gravity studies. Variation of radon concentration between 2.5 and 4.1 kBq/m3 was observed on or near the fault zone in exposed and concealed segments, whereas the lower bound variation of 1.1–2 kBq/m3 was encountered on points moving away from fault zone. This variation of radon concentration promisingly supported the idea of the existence of a fault zone beyond the cessation of surface signature. The argument was further validated through the relative gravity variation studies following the radon concentration. The Bouguer anomaly was calculated along all 16 profiles cross-cutting the fault zone. The regional gravity mapped along 231 points of investigation showed a variation between − 90 and 8 mGal. The residual gravity highlighting the effects of upper crust disturbance because of under-thrusting has shown anomalous values between − 11 and 18 mGal. The results when contoured have shown a good congruence with those received from radon concentration contrasts. Conclusively, it can be perceived that these two nondestructive and less laborious techniques work in composite usefully to delineate the unseen earthquake potential source.

Analysis of the spatial variation of indoor radon concentrations (national survey in Bulgaria).

This paper presents the methodology and results of the national radon survey in Bulgaria and its spatial variability. The measurements were carried out in 2778 dwellings using CR-39 track detectors over two successive 9 and 3-month periods from April 2015 to March 2016. The arithmetic (AM) and geometric (GM) means of annual indoor radon concentration were 111 ± 105Bq/m3 and 81Bq/m3 (GSD = 2.15), respectively. The distribution of data has been accepted to be log-normal. Two hypotheses have been investigated in the paper. The first one was a spatial variation of indoor radon concentration and the second was spatiality of the factor that influences radon variation. The indoor radon concentrations in the 28 districts have been significantly different, which prove the first hypothesis. The influence of the factors, geology (geotectonic unit, type of rock, and faults distance of the measuring site), type of the region, and the presence of the basement in the building on radon spatial variation, was examined. The analyses have been shown that they significantly affect radon variations but with a relatively small contribution in comparison to the radon variation between district. Furthermore, the significance and contribution of the investigated factors were different in each district, which confirmed the second hypothesis for their spatiality.

Uncertainties associated with assessing Ontario uranium miners’ exposure to radon daughters

The Ontario uranium miners study is a large (n = 28 546) cohort with low levels of radon exposure relative to other uranium miner cohorts. Multiple methods were used over time to estimate annual occupational exposure to radon daughters including: mine-specific extrapolations by mining engineers, area sampling in limited areas of the mines combined with approximate working time and lastly, consistent exposure sampling in different locations of the mine combined with workers’ time cards. Nonetheless, estimating exposures involves assumptions that lead to some uncertainty in occupational exposure characterisation arising from the assessment approach and variability within workplace, over time and by individual. An evaluation of the total uncertainty associated with radon daughter exposure estimation in Ontario miners over time has not been conducted. The objective of this study was to identify the contributing sources and assess the total uncertainty associated with estimating occupational radon daughter exposure among underground Ontario uranium miners over the course of uranium mining. The five sources of radon daughter exposure uncertainty evaluated were: natural variations in radon concentration, estimation of working time, precision of the radon measurement method, unintended errors during sampling, and record keeping and transcription of exposure data. These sources were examined separately for the period 1958 to 1967 and then 1968 onward due to changes in radon daughter concentration measurement practices between these periods. The magnitude of uncertainty associated with each of these sources over time were determined by reviewing historical literature on uranium mining in Ontario as well as through expert advice. Using the root sum square method, the total radon daughter exposure uncertainty was found to be 53 to 67% in the earlier period of uranium mining from 1958 to 1967. This decreased to 31 to 39% for the period 1968 to 1996 with natural variations of radon daughter concentrations in mines accounting for the largest percentage of uncertainty. This assessment provides an initial step in understanding the effect of exposure uncertainty on risk estimates. The impact of this uncertainty on the dose-response relationship between radon exposure and cancer risk will be assessed in future work.

The influence of uncertainties of radon exposure on the results of case-control epidemiological study

Purpose: Simulation of large-scale epidemiological study to identify the influence of uncertainties of radon exposure assessment on the excess relative risk of lung cancer.Materials and methods: Analysis of sources of uncertainties arising during radon epidemiologic case-control studies. Assessment of the uncertainties due to influence of long-term variations of radon concentration, exposure to radon in other places of human presence, except dwellings, quality of radon concentration measurements etc. Simulation by Monte Carlo technique of radon epidemiologic study, comparable to the pooled European radon case-control study, and assessment of uncertainties, which affect the evaluation of dose-effect dependence.Results: The uncertainties of personal exposure to radon are generally caused by the combined effect of long-term variations of radon concentration and the differences in the levels of radon concentration in homes and other places of human presence. The logarithmic standard deviation of this uncertainty is from 0.70 to 0.90. This value is ∼2 times higher than the uncertainty, applied for correction of the results in the pooled European radon case-control study. It is shown that for σerr < 1.0 regression calibration technique allows to make full correction of the uncertainty. The error in assessment of uncertainties of the exposure to radon concentration in the pooled European radon case-control study has led to an underestimation of excess relative risk of lung cancer incidence at least by 1.5 times.Conclusion: The error in an assessment of uncertainties of radon exposure in the pooled European radon case-control study has led to an underestimation of relative risk of lung cancer incidence at least by 1.5 times.

Measurement of Indoor Radon Concentration in Dalat area

A significant contribution to natural exposure of humans is radon gas, which emanates from the soil and may concentrate in dwellings. The level of radon exposure varies around the globe, but limited data are available on the daily variations of indoor radon concentrations. In this study, indoor radon measurements were performed continuously within one week at six different places in Dalat, Vietnam using the real time Smart Radon Detector Radon Eye+. The indoor radon behavior in a day follows a sine pattern, with peak values in the early morning and lowest values in the late afternoon. There are also some fluctuations at specific times due to different weather conditions. Indoor radon concentrations in the Dalat regions were found to exceed the recommended guidelines and thresholds; excessive radon levels warranting health concern were found (150.7-340.0 Bq/m3). Some corrective actions to reduce indoor radon concentrations were recommended. Annual effective doses on different age categories were also calculated.

Development of new radon monitoring systems in the Kamioka mine

Radioactivity from radon is a major threat for high-precision low energy physics experiments like the ones in the Kamioka Mine. We developed a new high sensitive radon monitoring system and conducted systematic radon concentration measurements for the first time in Kamioka. The system consists of portable radon detectors with a capacity of 1 L and new electronics based on Raspberry Pi. These radon detectors measure the radon in air with electro-static collection and a PIN photodiode. We measured the absolute humidity dependence of the 1-L radon detector for air to be $C_{F} (A_{H}) = (12.86 \pm 0.40) - (1.66 \pm 0.19) \sqrt{A_{H}}$ $\mathrm{(counts/day)/(Bq/m^3)}$. The background level of the 1-L radon detector is $0.65\pm0.15$ (stat.) count/day. This corresponds to a detection limit of $\sim0.4$ Bq/m$^3$ in a one-day measurement. Data was collected for a period of more than one year with twenty one 1-L radon detectors in the Kamioka mine. They indicate seasonal and day-night variations in radon concentration within the mine. These results also allow us to confirm the stability of the new Raspberry Pi electronics.

Indoor and Outdoor Radon Concentration Levels in Lebanon.

Lebanon's lung cancer rates, among the highest in the Arab region, contribute to the burden of noncommunicable diseases. A number of studies have shown that lung cancer risk increases when smokers vs. nonsmokers exposed to elevated radon levels are compared. This research employs indoor and outdoor space and time concentration surveys across Lebanon, where the smoking rate among the population is among the highest in the world. The distributional properties of measured radon concentration were shown to be lognormal with median indoor and outdoor concentrations of 17 and 10 Bq m, respectively. Standard deviation for indoor concentrations was 1.2 times smaller than its outdoor counterpart, suggesting that weather-related patterns affect outdoor radon concentration variability. No significant spatial association was detected across seasons for indoor and outdoor radon concentrations. Geographical location, proximity to faults, and housing construction material had no significant impact on outdoor and indoor radon concentration variations. When lognormal distributions were used to determine exceedance probability of the recommended reference radon concentration, they were smaller than 0.1%. While exhibiting high seasonal variability, the study shows that radon does not appear to be a public health concern in Lebanon.

A CASE STUDY ON THE USE OF SEASONAL CORRECTION FACTORS FOR INDOOR RADON MEASUREMENTS.

Radon concentration measurements were performed in the city Eskişehir, Turkey in order to quantify seasonal variation. Using the assumption that indoor radon concentrations exhibit annual cyclic behavior, Pinel's methodology was employed to obtain seasonal correction factors (SCFs). A total of 142 dwellings had radon concentration data for each season that enabled to obtain annual average radon concentrations. Estimated SCFs were applied to each of the 142 dwellings to assess the validity of the factors. The results demonstrate that even in a very small region significant variation in radon concentrations of different dwellings can be observed, and that a good care should be taken in applying SCFs to a short-term radon measurement to obtain average annual radon concentration.

Investigation of the relationship between rock strain and radon concentration in the tidal frequency-range

Changes in the radon gas concentration can precede geodynamic processes associated with tectonic, volcanic activities and earthquakes. For this reason the relationship between rock strain and radon concentration is an important scientific issue to be answered. According to the complexity of the radon emanation process influenced by environmental effects, the interpretation of radon concentration variation as a possible precursor of geodynamic processes is not yet resolved unambiguously. The Sopronbánfalva Geodynamic Observatory in Hungary is one of the few places where radon concentration and rock strain variations are simultaneously monitored. The object of this study is to investigate the connection between indoor radon concentration and rock strain in the tidal frequency-range on the basis of seven-year long data series measured in years from 2009 till 2015. The relationship between rock deformation and radon concentration was investigated together with the temperature and barometric pressure effects. It was found that the strain induced radon concentration variations are in the order of 10–100 Bq nstr−1, while the concentration variations bear more considerable similarity and relation to the temperature and barometric variations. The theoretical tide at the location of the measurement site and tidal components computed from strain, radon concentration, barometric pressure and temperature data were compared with each other. Spectral and tidal analysis of data demonstrated that only the thermally induced solar components S1 and S2 are present in the radon concentration but their amplitudes hardly exceed the spectral noise level. The principal lunar semidiurnal M2 and diurnal O1 tidal waves cause the largest rock strain variations. The lack of the O1 and M2 constituents in the radon concentration confirms the fact that the detected S1 and S2 tidal components appear due to the barometric tide and the daily variations of the temperature and barometric pressure.

Spatial variations of radon concentrations and equivalent gamma dose rate at faults in the Flysch and basinal clastic sediments of Central Moravia

Spatial variations of radon concentrations and equivalent gamma dose rate at faults in the Flysch and basinal clastic sediments of Central Moravia

Continuous measurement of equilibrium equivalent radon/thoron concentration using time-integrated flow-mode grab sampler

The continuous measurement of any physical entity is the finest approach to see the real-time variation of any concentration. In the present study, an effort has been made to see the continuous variation of radon and thoron progeny concentration (EERC and EETC) using time-integrated flow-mode sampler in which the deposition of progeny particles has been done in the filter paper in which an absorber has been mounted which specifically absorbs the alpha energies emitted by the progenies of radon or thoron. Also, the variation of thoron progeny concentration (EETC) using two different types of SSNTDs, LR-115 and CR-39, has been seen and it has been found that the measurement of EETC using both of the detectors is very much comparable with positive relationship (R = 0.89) between the results obtained.

Short-term variations of indoor and outdoor radon concentrations in a typical semi-arid city of Northwest China

To obtain basic data for adverse effects of radon (Rn) on human health, indoor and outdoor Rn concentrations were measured using a RAD7 Rn detector from Oct 2015 to Jun 2016 in Xi’an, China. The effects of air quality and ventilation conditions on the short-term variation of Rn concentrations were evaluated in detail. The results show that the outdoor Rn concentrations increased with the increase in degree of air pollution, and the indoor Rn concentrations decreased with the increase in ventilation rate under different airflow patterns. Some effective measures are proposed to reduce the effect of Rn exposure.

Across-fault distributions of radon concentrations in soil gas for different tectonic environments

The radon concentration in soil gas at the crustal surface is closely related to the development of local fractures. Therefore, the spatial variation in soil-gas radon concentrations across faults differs between fault zones located in different tectonic environments. This study investigates the Beiluntai thrust fault and the Haiyuan strike-slip fault in west China, which are assumed to be typical examples of the different types of faults. Radon concentrations in soil gas were measured at various locations around these faults, and the spatial variation in these concentrations was characterized along fault-perpendicular profiles. For normal fault, our results indicate that concentrations are usually highest at the fault, and decrease gradually away from the fault in either direction. For thrust, however, concentrations increase in the hanging wall approaching the fault, but decrease sharply at the fault. For strike-slip fault with extension across the fault, soil-gas radon concentrations are relatively high at the fault, and decrease gradually with distance from the fault. For strike-slip fault with contraction across the fault, soil-gas radon concentrations are relatively low at the fault, and increase gradually with distance from the fault.

Indoor radon concentration in Korearesidential environments.

The purpose of this study is to provide basic data for the evaluation and management of health effects with respect to exposure to radon within residential environments in South Korea. It is part of a case-control study to develop a management plan based on indoor radon exposure levels and assess their impact on health. To investigate the long-term cumulative concentration levels of radon, 599 patients who have respiratory diseases were recruited in South Korea, and alpha track detectors were installed in their residences for a period of 3months from mid-2015 to late 2016. A survey was then conducted to determine the factors affecting the radon concentration. The radon concentration levels were analyzed in conjunction with the survey results. The results show that the arithmetic mean of the radon concentrations in domestic residences was in the range of 70.8 ± 65.2Bq/m3. An analysis of covariance (ANCOVA) was performed to identify the environmental factors affecting the radon concentration and contributing to variations in the residential radon concentration based on the height of the residence. The results show that the contribution of the local environmental factor to the variation in radon concentration (p < 0.05) was greater than that of other environmental factors. Although no statistically significant difference was found with regard to the construction year of the building before the control (p > 0.05), the same was found with regard to the construction year after the control (p < 0.05).

Optimizing Sampling, Sample Processing and Analysis Methods for Radon (&amp;lt;SUP&amp;gt;222&amp;lt;/SUP&amp;gt;Rn) in Water by Liquid Scintillation Counting

Throughout the United States, laboratories use different sampling methods (“Direct Fill” vs. “Submerged Bottle” methods), sample preparations (“Simultaneous Drawing” vs. “Separate Drawing”), scintillators (“Mineral Oil” vs. “Opti-Fluor”), volume of water plus scintillator in the cocktail (“8 mL plus 8 mL” vs. “10 mL plus 10 mL”), and liquid scintillation counting assays (“Full Spectrum: 0 - 2000 keV” vs. “Region of Interest: 130 - 700 keV”) for analyzing radon (222Rn) in water. We compared these and few other variables on the recovery of radon from two “Proficiency Test (PT)” samples and four “Household Well Water” samples from Georgia. The “130 - 700 keV” assay had significantly higher radon recovery than the “0 - 2000 keV” assay. The “Direct Fill” sampling produced significantly lower radon recovery than the “Submerged Bottle” sampling. “Simultaneous Drawing” of both scintillator and water sample yielded higher radon recovery than “Separate Drawing”. Air bubble in the samples resulted in significant loss of radon gas; and such loss became greater as the air bubble was larger. A “10 mL scintillator + 10 sample” combination appeared better than “8 mL scintillator + 8 mL sample”. Mixing scintillator and sample in the laboratory, when compared with doing it on-site, was found superior for better results and practicality of testing radon in private well waters. “Mineral Oil” scintillator provided higher radon activity than “Opti-Fluor”. However, in 10 consecutive measurements of the two proficiency test (PT) samples at 60 days interval (i.e., with full ingrowing), “Mineral Oil” overestimated the radon activity compared to the predicted/assigned value in most cases, whereas “Opti-Fluor” invariably produced results close to the predicted/assigned value. There were noticeable temporal variations in both radon and uranium concentrations in the study wells; nevertheless, uranium and radon concentrations had good positive correlation. Despite this, the use of uranium concentration over 30 ppb (the MCL of uranium in drinking water) as a trigger for recommending test for radon in well water remains questionable because there may be the safe level of uranium but unsafe level of radon in a well and vice versa.

Seasonal variation of radon concentration in water and assessment of whole-body dose to the public along South-west coast of Kerala, India

The South-west coast of Kerala is a well-reported high background radiation area. Hence, the radiological protection of the population in this region has great concern. In view of this, the study has been undertaken to understand the distribution of radon ( 222 Rn) concentration in drinking water collected from the region. The seasonal variation of radon concentration in drinking water also forms part of the study. Emanometry method is used for the quantification of dissolved radon concentration in water collected from various open wells. The mean values of radon concentration obtained for pre- and post-monsoon were 0.95 Bq/l and 0.58 Bq/l, respectively. The whole-body dose ranges from 0.39 to 29.34 μSv/y for premonsoon and 1.33–18.76 μSv/y for postmonsoon. The average value of effective dose was below the recommended limit of 0.1 mSv/y suggested by WHO and EU council, and the water from the region can be safely consumed from the radiological protection point. All the results are presented and discussed in the manuscript.

Seasonal variation of radon concentration in drinking water and assessment of whole-body dose to the public along coastal parts of Kerala, India

Context: Some of the coastal parts of Kerala are well-reported high background radiation area. Hence, the radiological protection of the population in this region has of great concern. Aims: In view of this, a study has been undertaken to understand the distribution of radon (222Rn) concentration in drinking water collected from the region. The seasonal variation of radon concentration in drinking water also forms part of the study. Assessment of whole-body dose and excess lifetime cancer risk (ELCR) to the public were also done. Subjects and Methods: Emanometry method is followed for the quantification of dissolved radon concentration in water collected from various open wells. Results: Average value of ELCR at different locations is ranged from 0.009 × 10−3 to 0.123 × 10−3. Conclusion: The average value of effective dose was below the recommended limit of 0.1 mSv/y suggested by the WHO and the EU council. The present study indicates that water from the region can be safely consumed from the radiological protection point of view. All the results are presented and discussed in detail in the manuscript.

Analysis of queuing mine-cars affecting shaft station radon concentrations in Quzhou uranium mine, eastern China

Abstract Shaft stations of underground uranium mines in China are not only utilized as waiting space for loaded mine-cars queuing to be hoisted but also as the principal channel for fresh air taken to working places. Therefore, assessment of how mine-car queuing processes affect shaft station radon concentration was carried out. Queuing network of mine-cars has been analyzed in an underground uranium mine, located in Quzhou, Zhejiang province of Eastern China. On the basis of mathematical analysis of the queue network, a MATLAB-based quasi-random number generating program utilizing Monte-Carlo methods was worked out. Extensive simulations were then implemented via MATALB operating on a DELL PC. Thereafter, theoretical calculations and field measurements of shaft station radon concentrations for several working conditions were performed. The queuing performance measures of interest, like average queuing length and waiting time, were found to be significantly affected by the utilization rate (positively correlated). However, even with respect to the “worst case”, the shaft station radon concentration was always lower than 200 Bq/m3. The model predictions were compared with the measuring results, and a satisfactory agreement was noted. Under current working conditions, queuing-induced variations of shaft station radon concentration of the study mine are not remarkable.