Rn Progeny Research Articles

Radiation dose estimation for indoor radon, thoron and their progenies using a stochastic method-a small-scale survey in Wuhan, China.

Passive radon monitors with CR-39s are widely used in major epidemiological surveys. However, the conventional CR-39 track density determining strategy makes it difficult to accurately estimate the concentration because of the heterogeneity of tracks on CR-39s. This study introduced a stochastic method, Latin hypercube sampling, to improve the track density determining strategy and provide the probability distribution of 222Rn concentration and equilibrium equivalent thoron concentration. The first 222Rn and 220Rn discriminated survey was conducted in Wuhan, China, in 2018 using RADUET® and deposition-based passive 220Rn progeny monitors and applying the stochastic method to the measurement. The results indicate that the stochastic method could decrease the effects of the track heterogeneity on the CR-39s and provide reliable results. The 220Rn progeny contributed more than 40% of the total inhalation dose in the survey, which cannot be ignored in urban family dwellings.

An update on soil gas harvesting technique as a non-depleting source of 222Rn for a large volume calibration chamber for long-term exposure experiments

ObjectiveTo demonstrate the versatility of the natural soil gas harvesting technique, coupled with a semi-dynamic injection algorithm, as an efficient and reliable source for continuous 222Rn delivery to a large-volume calibration chamber across different soil conditions and climatic conditions. MethodsLong-term experiments were performed during three seasons of a year in a tropical monsoonal climatic region with high rainfall on the Southwest Coast of India. Soil gas extraction was performed using soil-gas probes, inserted to 1 ​m deep into the ground. Soil gas was harvested at a flow rate of 60 L/min, passed through a moisture trap, a 222Rn progeny filter, and a delay volume and pumped into a 222Rn calibration chamber of volume 22.7 ​m3. Continuous monitoring of 222Rn concentration in the chamber was performed using ionization chamber-based reference monitors. To achieve and maintain the desired 222Rn concentration values in the calibration chamber, the semi-dynamic injection method was adopted, in which the 222Rn concentration in the soil gas was monitored periodically, and injection into the chamber was controlled using a well-defined pumping algorithm. Three ranges of 222Rn concentration values were chosen as the target values to be maintained in the calibration chamber for long-term experiments (15 ​d): low concentration (500–1,000 Bq/m3), medium concentration (1,000–10,000 Bq/m3), and high concentration (10,000–25,000 Bq/m3). ResultsThe achieved 222Rn concentration values were in good agreement with the target values, with deviations of 12%, 8% and 5% for the low, medium and high concentration exposures, respectively, during the summer season. During the monsoon season, the deviations between the target and the achieved concentration values were 12%, 10% and 5% for low, medium and high concentration exposures, respectively, and the corresponding deviations were 12%, 4%, and 5% for the winter season. These deviations are well within the cumulative uncertainty associated with the measurements. ConclusionsThe results of this study conclusively demonstrate that the soil gas harvesting method, when coupled with the semi-dynamic injection approach, is a reliable method for generating and maintaining the desired 222Rn concentration in the large volume calibration chamber during different seasons and environmental conditions.

A high-sensitivity radon emanation detector system for future low-background experiments

Radioactive radon atoms originating from the primordial 238U and 232Th decay chains are constantly emanated from the surfaces of most materials. The radon atoms and their radioactive daughter isotopes can significantly contribute to the background of low-background experiments. The 222Rn progeny 214Pb, for example, dominates the background of current liquid xenon-based direct dark matter detectors. We report on a new detector system to quantify the 222Rn surface emanation rate of materials. Using cryogenic physisorption traps, emanated radon atoms are transferred from an independent emanation vessel and concentrated within the dedicated detection vessel. The charged radon daughter isotopes are collected electrostatically on a silicon PIN photodiode to spectrometrically measure the alpha decays of 214Po and 218Po. The overall detection efficiency is ∼ 36 % for both polonium channels. The radon emanation activity of the emanation vessel was measured to be (0.16± 0.03) mBq, resulting in a detection sensitivity of ∼ 0.06 mBq at 90 % C.L.

PM1, PM2.5 and PM10 size fraction distribution under steady-state conditions in a walk-in type 222Rn calibration chamber facility.

Attachment of 222Rn progenies, upon their formation, to the atmospheric aerosols and inhalation of these radioactive aerosols causes inhalation dose to the human being. Aerosols have the characteristics of small particle size, long-time suspension and long-distance transmission and easy access to the deep respiratory tract. Aerosols are responsible for viral infection risk such as the recent worldwide pandemic caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2, or COVID-19). Understanding the formation and behaviour of aerosols in a confined environment in various human habitations is essential to combat such detrimental exposures. Experiments have been performed to study the distribution of aerosol size fractions in the walk-in type 222Rn calibration chamber. The real-time applied particle technology monitors (APT-Maxima stationary monitors) were used for the simultaneous measurements of PM1, PM2.5, and PM10 size fractions. The variation of the mass densities (μgm-3) of different size fractions at different positions inside the chamber was monitored by placing APTs. The PM1, PM2.5, and PM10 sizes fractions were distributed homogeneously within the chamber volume and the concentration ratios of these fractions were 1:1.5:1.6 for concentration values of < 1500μgm-3, and 1:7:9 for the concentration values of > 1500μgm-3.

Assessments of annual effective doses for population and estimation of environmental risk in the vicinity of coal-fired power plant Kakanj, Bosnia and Herzegovina

The paper describes radioactivity monitoring and radiological risk assessment procedures for the population and the environment in three villages located around the coal-fired power plant. The dose assessments were performed after long-term radioactivity monitoring that was carried out in the production process and in the vicinity of the coal-fired power plant Kakanj, Bosnia and Herzegovina.The estimated annual effective doses for the population living in the observed villages were in the range of 1.89–2.13 mSv. The most significant contributions were delivered from ingestion of food and water (0.55–0.63 mSv y−1); external exposure from building materials (0.44–0.62 mSv y−1) and inhalation of radon (222Rn) progeny (0.29–0.62 mSv y−1).The inhalation doses from flying radionuclide particles were not significant with values in the range of 0.0056–0.0062 mSv y−1 for inhalation of 235U, 238U, 226Ra, and 232Th. External terrestrial doses were in the range of average world values (0.070–0.094 mSv y−1).Environmental risk was estimated using the ERICA tool which did not highlight any threatened species. A conservative approach with a lower dose screening value (10 nGy h−1) indicated the risk for lichens and bryophytes as terrestrial organisms with high accumulation capacity for natural radionuclides.

226Ra measurement via gamma-ray spectrometry of 222Rn progeny – quantification of radon losses from sample capsules

ABSTRACT Radium-226 detection in sediment samples is generally executed by means of gamma-ray spectrometry. Data evaluation relies (besides the 186.2 keV 226Ra gamma peak) on the combined analysis of major gamma peaks that are produced by the short-lived radon (222Rn) daughters 214Pb and 214Bi. Precondition for this detection approach is equilibrium decay of all members of the decay chain between 226Ra and 214Bi. In closed systems, this equilibrium is reached after about five half-lives of 222Rn (19 days). However, a closed system can only be guaranteed if the capsule which contains the sample prevents diffusive escape of radon. Such radon-tightness cannot be guaranteed for a wide range of plastic materials. Due to its polymer structure, plastic material generally tends to allow radon diffusion and hence radon loss from the sample resulting in a disturbance of the required decay equilibrium. The paper introduces an approach that allows quantifying radon loss from sample capsules by direct radon measurements using mobile radon detection equipment. The experimental findings are supported by theoretical considerations. An examined alternative approach based on the offset of the 186.2 keV data point from an efficiency function that is calculated exclusively from short-lived radon progeny peaks in the gamma-ray spectrum did not prove to be applicable due to a lack of supporting peaks in the low-energy section of the spectrum.

Impact of radon on personal contamination monitors at the exit of the restricted controlled areas in EDF nuclear power plant

Background: Between 2008 and 2017, EDF has progressively replaced its old Personal Contamination Monitors (PCM) with a new generation to strengthen the control of the workers at the exit of the restricted controlled areas. One of the novelties of the new PCM generation is the introduction of gamma channels which, coupled to the beta channel, allows a more reliable and more precise measurement. The new PCM also includes a better monitoring of the C2 portals alarms triggering system, a greater detection surface to minimize the dead zone and carries out morphological compensation to take into account the attenuation of the gamma background by the body. This new PCM is very efficient and capable of detecting low contamination activities. The sensitivity of this monitoring system is such that the solid progeny of 222Rn deposited on clothes (such as the 214Pb and the 214Po) could in some cases be detected and triggered the C2 portals alarm. Objective: In order to quantify the impact of radon (222Rn) and its progeny on the C2 portals triggers, a specific study has been conducted. Beyond the physical aspect, several purposes are targeted: (1) to provide quantitative explanations about the C2 alarms attributed to radon and determine which channels are more affected by the 222Rn progeny; (2) to determine the existence of a relation between C2 alarms and high 222Rn volume activity; (3) to optimize practices at the exit of the Restricted Controlled Areas (RCA), for example, adapt waiting time before control in PCM. The study consisted in measuring the activity of radon progeny deposited on several types of suits used in EDF Nuclear Power Plants (NPPs). To assess the impact of the 222Rn, several factors have been studied such as the 222Rn exposure time, the 222Rn concentration and the nature of textile fibers constituting clothes. For this study, several facilities from the Laboratoire de Physique des deux infinis de Bordeaux (LP2i Bordeaux) have been used, including a 222Rn emanation standard source and various emanation chambers between 60 L and 750 L. A specific calibration method to characterize radon progenies deposited has been developed (see Sects. 2.4 and 3). The 222Rn concentration in the sample exposure environment is verified both using a commercial (see Sects. 2.4 and 3) and experimental high sensitivity radon detectors. The measurements of the 222Rn progeny on clothes are made immediately after exposure by gamma spectrometry control on a High Purity Germanium (HPGe) detector. This experiment has been carried out at the PRISNA measurement platform (Plateforme Régionale Interdisciplinaire de Spectrométrie Nucléaire en Aquitaine) located in LP2I Bordeaux. Conclusions: In this study, several phenomena have been highlighted for a better understanding of the C2 portal triggering. We validate that in presence of 222Rn volume concentration activity lower than 300 Bq/m3, an alarm in beta channels of C2 portals can be triggered because of the presence of the radon progeny on clothes. The triggering of the gamma channels could appear only if the volume concentration activity of radon is higher than 3000 Bq/m3. The results obtained in this study could led to optimize and harmonize the practices at the exit of Restricted Controlled Area (RCA) like adapt waiting time before control in PCM.

Investigation of 220Rn and its Progeny Distribution in a Test Chamber

Introduction: Due to the widespread belief that 220Rn's levels are minimal due to its shorter half life and that its contribution to the overall inhalation dose is neglected in the presence of other important natural radiation sources, data for 220Rn in indoor and industrial environments are few.&#x0D; Objectives: To find the distribution of radon, thoron and their progeny levels with wall and floor distances.&#x0D; Methods: The experimental methodology is as per the standard protocol provided by the Environmental Assessment Division, Department of Atomic Energy, Bhabha Atomic Research Centre, Government of India, Mumbai for radon groups working in the country. Measurements of radiation levels and the concentrations of radionuclides in the environment are accomplished employing appropriate nuclear instruments. The radon, thoron and their progeny levels were determined using Solid State Nuclear Track Detectors and the tracks formed in these films were counted by Spark Counter detailed methods are discussed elsewhere.&#x0D; Results At the room's walls, ceiling, and floors, 220Rn concentrations were highest and rapidly decreased as one moved away from them. Indoors, the concentration of 220Rn progeny is independent of the distance between walls. Research on 220Rn diffusion from each wall of the construction materials used and factors affecting the levels of 220Rn progeny in homes are two examples of the extensive and continuous study needed to estimate the dosage due to 220Rn and its offspring.&#x0D; Conclusions: The assessment of public exposure to natural radiation, particularly the exposure from 220Rn and its offspring, has to be conducted more thoroughly across the country.

A methodology to determine 212Pb, 212Bi, 214Pb and 214Bi in atmospheric aerosols; Application to precisely obtain aerosol residence times and Rn-daughters’ equilibrium factors

Progeny of 222Rn and 220Rn, (212Pb, 212Bi, 214Pb and 214Bi) are essential to assess radiological hazard, external and internal doses, residence times and equilibrium factors. Precise measurements of these nuclides are quite complex due to their very short half-lives. This study outlines a new and precise methodology to measure these nuclides. Radon-222 and 220Rn were measured using a radon monitoring system, while their respective progenies were collected in an atmospheric filter using an ASS-500 sampler and measured by gamma-ray spectrometry. The 212Pb concentrations were very similar to the thoron ones, where all 212Bi/212Pb ratios were consistently less than 1. The relative uncertainties, σr, of the 212Pb and 212Bi activity concentrations, and 212Bi/212Pb activity ratio are generally less than 10%. Moreover, 214Pb/222Rn ratios were about 0.7, agreeing well with previous works. The σr for 214Pb, 214Bi and 214Bi/214Pb were generally less than 6%. This methodology was applied to estimate aerosol residence times using the 214Pb/222Rn and 212Bi/212Pb activity ratios, and to obtain equilibrium factors, achieving consistent results. Furthermore, the methodology consistency and validity range were studied with time elapsed between sampling end and counting start, and the sampling durations, finding the optimum times to precisely determine 212Pb, 212Bi, 214Pb and 214Bi.

Radon emanation from dust of varying composition and size

222Rn emanating from environmental dust constitutes an important background component for many low-energy, low-rate experiments. Radon emanation rates from dust and rock, thus, are important for experiment planning. In this paper, we report measured radon emanation fractions for five types of dry dust differing in grain size and composition. These data were obtained by a novel technique in γ-spectroscopy, measuring emanated and non-emanated 222Rn progeny activities as well as the parent 226Ra activity in a time series. The range of observed radon emanation fractions is (3.7 ± 2.0)% to (16.2 ± 0.9)%. Four of the five samples are standardized samples available commercially, so additional investigations of these samples may be readily carried out.

INFLUENCE OF AIRWAY GEOMETRY ON RADON RISK ASSESSMENT IN ADULTS AND CHILDREN (MICRODOSIMETRIC APPROACH).

The aim of this work was to use the microdosimetric threshold energy model to study the effects of alpha-emitting 222Rn progeny on the probability of developing lung cancer. The results suggest that the radiation risk may increase by several times as the thickness of the surface layer decreases. The thicker the protective mucus layer and the deeper the sensitive target cells are located in the tissue, the less radiation damage the same dose produces. These findings have been applied to children of various ages. As children grow older, their lungs enlarge, the mucus layer thickens and the cells sensitive to radiation damage move deeper into the lung tissue, resulting in a reduction of radiation risk. The fraction of affected target cells is not only a function of dose but also of lung tissue depth. The results indicate that children can be several times more vulnerable to radiation than adults.

AlphaCAMM, a Micromegas-based camera for high-sensitivity screening of alpha surface contamination

Surface contamination of 222Rn progeny from the 238U natural decay chain is one of the most difficult background contributions to measure in rare event searches experiments. In this work we propose AlphaCAMM, a gaseous chamber read with a segmented Micromegas, for the direct measurement of 210Pb surface contamination of flat samples. The detection concept exploits the readout capabilities of the Micromegas detectors for the reconstruction of 210Po alpha tracks to increase the signal-to-background ratio. We report here on the design and realization of a first 26 × 26 cm2 non-radiopure prototype, with which the detection concept is demonstrated by the use of a new algorithm for the reconstruction of alpha tracks. AlphaCAMM aims for minimum detectable 210Pb activities of 100 nBq cm-2 and sensitivity upper limits about 60 nBq cm-2 at 95% of C.L., which requires an intrinsic background level of 5×10-8 alphas cm-2 s-1. We discuss here the prospects to reach these sensitivity goals with a radiopure AlphaCAMM prototype currently under construction.

Radon in dead-end caves in Europe

We report the results of 3-years of Radon-222 monitoring in six show caves across Europe, selected with the feature of having only one, or no natural entrance, defined as dead-end caves. The caves are located in Spain, Slovakia, Slovenia, and Czechia. The consecutive monitoring was performed between January 2017 and January 2020. Continuous measurements of the radon activity concentration using spectrometry detection and analysis of the α-particles of 222Rn progeny were performed. Meteorological parameters influencing gas flow were recorded inside and outside of the caves. Although the radon activity concentrations differed from one cave to another, all six of the studied caves revealed very similar trends, showing evident seasonal variability with higher values in summer and lower values in winter. The measured values of radon activity concentrations ranged between 633 and 26,785 Bq/m3. The temperature differences between the inside and outside of the caves is the main radon movements driving force. The results of this study have significant practical implications, making it possible to provide cave administrators with recommendations regarding employee or visitor time-limited access to the investigated caves. Ours is the first comparative study encompassing the most interesting dead-end caves in Europe.

Radiation exposure due to 222Rn, 220Rn and their progenies in three metropolises in China and Japan with different air quality levels

Radiation exposure due to radon contributes most of the ionizing radiation exposure to people among natural radiation sources. This research measured the 222Rn, 220Rn by the RADUET and their progeny concentrations by the improved deposition based 222Rn and 220Rn progeny monitor, and the contribution of outdoor PM2.5 concentrations to indoors by a modified steady-state mass balance model in Beijing, Changchun, China and Aomori, Japan. Based on these results, we preliminarily explored the relevance between the city level outdoor PM2.5 exposure and indoor 222Rn, 220Rn inhalation exposure in these three metropolises with different air quality levels. The average equilibrium equivalent radon concentration (EERC) and equilibirum equivalent thoron concentration (EETC) indoor were 17.2 and 1.1 Bq m−3 in Beijing, 19.4 and 1.3 Bq m−3 in Changchun, and 10.8 and 0.9 Bq m−3 in Aomori, respectively. The indoor EERC and EETC in Beijing showed 1.4 and 2.2 times as high as that measured in 2006. The indoor radiation dose due to inhalation presented in a descending order as Changchun, Beijing and Aomori, which were in accordance with their outdoor 222Rn concentrations. The indoor radiation doses due to 220Rn contributed 30% of the total dose in the three cities, indicating that 220Rn cannot be neglected when evaluating indoor radiation dose. It should be noted that, the indoor PM2.5 concentrations of outdoor origin presented strong correlation (r = 0.772) with indoor EETC and moderate correlation (r = 0.663) with indoor EERC, indicating that the PM2.5 of outdoor origin can break the concentration balance of the indoor PM2.5, then affect the indoor 222Rn and 220Rn behaviors, and further affect the inhalation exposure of radon.

Natural Radioactivity and Radon Exhalation from Building Materials in Underground Parking Lots

The change of natural ionizing radiation and the radon exhalation rates from typical building materials in underground parking lots are presented in the article. The activity concentration of natural radionuclides 232Th, 226Ra, and 40K in six important types of construction materials, which are mostly used in Lithuania, were analyzed using high-resolution gamma spectroscopy. The highest values were found in concrete and ferroconcrete samples: 226Ra 44 and 90 Bq kg−1; 232Th 29 and 34 Bq kg−1; 40K 581 and 603 Bq kg−1. A strong positive correlation (0.88) was observed between radium activity concentration and radon concentration. The activity indexes (Iα and Iγ) and radium equivalent activity (Req) evaluating the suitability of materials for such constructions from the view of radiation safety were determined. The average values of the calculated absorbed dose rate in samples ranged from 18.24 nGy h−1 in the sand to 87.26 nGy h−1 in ferroconcrete. The calculated annual effective dose was below the limit of 1.0 mSv y−1. The values of the external and internal hazards index (Hex and Hin) were all below unity, and the values of Iγ and Iα were below the recommended levels of 0.5 and 1. Dosimetric analysis of underground parking lots was carried out. It was determined that the external equivalent dose rate caused by the 222Rn progeny radiation in the underground car parking lots varies from 17 to 30% of the total equivalent dose rate.

Inhalation dose in the indoor environment of Eloor industrial area, Kerala, India

Radon (222Rn) and Thoron (220Rn), the members of Uranium and Thorium decay series respectively, are ubiquitous in nature. Being airborne alpha active radioisotopes, they are the major contributors of inhalation dose especially in the indoor environments. This study measures the Potential Alpha Energy Concentration (PAEC) of radon/thoron progenies in the dwellings of Eloor industrial region in Kerala and thereby evaluate the internal/inhalation dose to the population. Aerosol samples were collected from 100 locations in the study area using high volume air sampler and gross particulate activity measurement was done using ZnS(Ag) alpha counter. The PAEC of radon progeny in the study area varied from 0.13 to 2.94 and that of thoron progeny varied from 0.3 to 7.7. It has been observed that the dwelling with marble floor possesses relatively higher concentration of radon and thoron progenies while lower concentrations were observed in dwellings with tile floors. Taking the mean concentrations of 222Rn and 220Rn progeny levels of 100 samples collected, the inhalation dose was 0.14 mSvy-1 for radon and 0.09 mSv y-1 for thoron, which delivers a total inhalation dose of 0.23 mSv y-1 to the population residing in that area. Measured data show below compared to the ICRP recommended action level of 3–10 mSvy-1 for general populace. Although measured data requires no immediate action to reduce the hazardous radon and thoron level in the studied area, however the radiation risk from such hazardous gas is not completely discarded. Since human spent more than 80% of time in indoor and the radiation hazards follows linear no threshold model, therefore the indoor environment should be well ventilated to reduce any unexpected health hazards.

Regulation and control methods for the unattached fraction of 220Rn progeny in a 220Rn progeny chamber

The unattached fraction of 220Rn progeny is one of the key parameters in lung dose evaluation models. To study the behavior of unattached 220Rn progeny and to prepare for calibration of the unattached 220Rn progeny monitors, a 220Rn progeny chamber that could stably regulate different unattached fractions of 220Rn progeny was established. A recirculation loop to eliminate the effects of the sampling and a loop connected to the dilution chamber to supplement the carrier aerosol were set up. Also, a theoretical model regarding the regulation of the unattached fraction of 220Rn progeny was established. Continuous measurements of the unattached fraction were conducted using the combination of a single-layer wire screen and a filter membrane. The experimental results showed that, under different aerosol levels, the relative standard deviation (RSD) of 212Pb concentration during the continuous samplings was within 10.7% and the RSD of the unattached fraction of 212Pb was within 9.9%. The relative deviation between the theoretical and the experimental values of 212Pb concentration was within 16.7% and the model calculation values of the unattached fraction of 212Pb were consistent with measured results.

Simulation of radon-222 with the GEOS-Chem global model: emissions, seasonality, and convective transport

Abstract. Radon-222 (222Rn) is a short-lived radioactive gas naturally emitted from land surfaces and has long been used to assess convective transport in atmospheric models. In this study, we simulate 222Rn using the GEOS-Chem chemical transport model to improve our understanding of 222Rn emissions and surface concentration seasonality and characterize convective transport associated with two Goddard Earth Observing System (GEOS) meteorological products, the Modern-Era Retrospective analysis for Research and Applications (MERRA) and GEOS Forward Processing (GEOS-FP). We evaluate four global 222Rn emission scenarios by comparing model results with observations at 51 surface sites. The default emission scenario in GEOS-Chem yields a moderate agreement with surface observations globally (68.9 % of data within a factor of 2) and a large underestimate of winter surface 222Rn concentrations at Northern Hemisphere midlatitudes and high latitudes due to an oversimplified formulation of 222Rn emission fluxes (1 atom cm−2 s−1 over land with a reduction by a factor of 3 under freezing conditions). We compose a new global 222Rn emission scenario based on Zhang et al. (2011) and demonstrate its potential to improve simulated surface 222Rn concentrations and seasonality. The regional components of this scenario include spatially and temporally varying emission fluxes derived from previous measurements of soil radium content and soil exhalation models, which are key factors in determining 222Rn emission flux rates. However, large model underestimates of surface 222Rn concentrations still exist in Asia, suggesting unusually high regional 222Rn emissions. We therefore propose a conservative upscaling factor of 1.2 for 222Rn emission fluxes in China, which was also constrained by observed deposition fluxes of 210Pb (a progeny of 222Rn). With this modification, the model shows better agreement with observations in Europe and North America (&gt; 80 % of data within a factor of 2) and reasonable agreement in Asia (close to 70 %). Further constraints on 222Rn emissions would require additional concentration and emission flux observations in the central United States, Canada, Africa, and Asia. We also compare and assess convective transport in model simulations driven by MERRA and GEOS-FP using observed 222Rn vertical profiles in northern midlatitude summer and from three short-term airborne campaigns. While simulations with both GEOS products are able to capture the observed vertical gradient of 222Rn concentrations in the lower troposphere (0–4 km), neither correctly represents the level of convective detrainment, resulting in biases in the middle and upper troposphere. Compared with GEOS-FP, MERRA leads to stronger convective transport of 222Rn, which is partially compensated for by its weaker large-scale vertical advection, resulting in similar global vertical distributions of 222Rn concentrations between the two simulations. This has important implications for using chemical transport models to interpret the transport of other trace species when these GEOS products are used as driving meteorology.

Circulation of Radon Progeny in the Terrestrial Atmosphere During Thunderstorms

AbstractWe describe a new phenomenon in atmospheric physics—222Rn progeny circulation during thunderstorms. The enhancement of the natural gamma radiation during thunderstorms was measured with precise gamma ray spectrometers. Results of measurements performed at Aragats mountain in Armenia during summer 2020 demonstrate the Rn progeny lifted to the atmosphere by a near‐surface electric field are returned backward to the ground by rain precipitation. Thus, thunderstorms not only return negative charge to the Earth by lightning flashes but also maintain Rn progeny circulation in the atmosphere; it this way, significantly enlarging natural gamma radiation above the Earth surface and Radon concentration in the atmosphere.

Study of ambient gamma dose levels at national atmospheric research laboratory, Gadanki, India

Simultaneous observations of ambient gamma dose levels, temperature, relative humidity, and atmospheric pressure were carried out at National Atmospheric Research Laboratory (NARL), Gadanki, India (13.459°N and 79.175°E), from November 2011 to May 2014. The results show that about 92% of ambient gamma dose values lie between 150 and 200 nSv/h and best possible fit resulted in Gaussian fit with adjusted R2 of 0.99. A weak Pearson's correlation coefficient was found between ambient gamma dose levels and selected meteorological parameters measured over the location. No seasonal trend was observed in ambient gamma dose levels, but pronounced seasonal variations in temperature, relative humidity, and air pressure were found. A sudden increase in ambient gamma levels was observed during precipitation event (Nilam cyclone) and may be attributed to an additional contribution of precipitation washed 222Rn progeny aerosols within the atmosphere. The mean ambient gamma dose over NARL was 186 ± 4.3 nSv/h and is within world average given by UNSCEAR.