222Rn Concentrations Research Articles

Assessment of 222Rn, 226Ra, 238U, 218Po, and 214Po activity concentrations in the blood samples of workers at selected building material factories in Erbil City

Assessment of 222Rn, 226Ra, 238U, 218Po, and 214Po activity concentrations in the blood samples of workers at selected building material factories in Erbil City

Geochemical precursory characteristics of soil gas Rn, Hg, H2, and CO2 related to the 2019 Xiahe Ms5.7 earthquake across the northern margin of West Qinling fault zone, Central China

The Xiahe Ms5.7 earthquake occurred in Xiahe county, Gannan prefecture, China (35.10°N, 102.69°E) on October 28, 2019, with a source depth of 10 km. This study investigates the spatial and temporal evolution characteristics of cross-fault soil gas concentrations prior to the Xiahe Ms5.7 earthquake by analyzing Rn, Hg, H2, and CO2 data collected from 11 profiles across the northern margin of the West Qinling fault zone from 2016 to 2019. The spatial distribution of these gases showed varying trends, with Rn concentration intensity decreasing from the Wushan segment to the east and west sections, while Hg, H2, and CO2 all broke the trend in the West Qinling fault zone's northern margin. The soil gas concentration intensity demonstrated a significant response to the Xiahe Ms5.7 earthquake, particularly in the west Ganjia sections. By integrating the seismogenic model and numerical simulation results, we explored the physical mechanism underlying these abnormal trends. Our findings suggest that the continuous decline characteristic of fault gas could be a valuable indicator of fracture tectonic activity, while an upward trend after continuous decline may signal a medium and short-term seismogenic event in the source area. These results provide a foundation for improved tracking of earthquake location and timing in a fault zone through cross-fault soil gas methods, highlighting the importance of enhancing deep fluid flow monitoring and seismogenic model research in fault zones.

Spatial distribution of radon contamination in hot springs water and its cancer and non-cancer risks in the Hunza-Nagar valley, Pakistan.

Radon (222Rn) is a ubiquitous radioactive gas and could threaten human life due to its potential for cancer and non-cancer risks. This study examined the measurement of 222Rn concentration and associated health risks in the hot springs of Hunza-Nagar valley. For this purpose, the hot springs water of Hunza and Nagar districts and the background sites were analyzed for 222Rn concentration using the RAD7 detector (Durridge Company, USA). The average concentrations of 222Rn were 46.1 ± 0.94, 65.3 ± 0.45, and 5.47 ± 0.25Bq/L in the Hunza district, Nagar district, and background sites, respectively. Results showed that 222Rn concentrations of hot springs water were multifold higher than the background sites. 222Rn concentrations for hot springs water in Hunza-Nagar valley had surpassed the maximum contamination level set by the US environmental protection agency (USEPA). Humans' annual mean exposure dose rates of various age groups were calculated for the estimated lifetime cancer risk (ELCR) and non-cancer risks. The total annual mean exposure doses from 222Rn in water (EwTotal) values were (187 ± 3.80, 265 ± 1.84, and 22.2 ± 1.02μSv/a) for infants (143 ± 2.92, 203 ± 1.40, and 17.0 ± 0.78μSv/a) children, and (138 ± 2.80, 196 ± 1.35, and 16.4 ± 0.76μSv/a) adults in the Hunza district, Nagar district, and background, respectively. Among the age groups of humans, infants showed a higher risk than others. Results showed that hot springs water consumption surpassed the world health organization threshold of 100μSv/y for chronic or non-cancer and USEPA 0.1 × 10-3 for ELCR risks.The concentration of 222Rn showed a positive correlation (> 0.68) with hot springs' water temperature and pH suggesting a common origin.

High-Throughput Computational Screening of Two-Dimensional Covalent Organic Frameworks (2D COFs) for Capturing Radon in Moist Air.

Radon (Rn) and its decay products are the primary sources of natural ionizing radiation exposure for the public, posing significant health risks, including being a leading cause of lung cancer. Porous material-based adsorbents offer a feasible and efficient solution for controlling Rn concentrations in various scenes to achieve safe levels. However, due to competitive adsorption between Rn and water, finding candidates with a higher affinity and capacity for capturing Rn in humid air remains a significant challenge. Here, we conducted high-throughput computational screening of 8641 two-dimensional covalent organic frameworks (2D COFs) in moist air using grand canonical Monte Carlo simulations. We identified the top five candidates and revealed the structure-performance relationship. Our findings suggest that a well-defined cavity with an approximate spherical inner space, with a diameter matching that of Rn, is the structural basis for a proper Rn capturing site. This is because the excellent steric match between the cavity and Rn maximizes their van der Waals dispersion interactions. Additionally, the significant polarization electrostatic potential surface of the cavity can regulate the adsorption energy of water and ultimately impact Rn selectivity. Our study offers a potential route for Rn management using 2D COFs in moist air and provides a scientific basis for further experimentation.

222Rn and CO2 monitoring in soil and indoor atmosphere to understand changes in the gaseous dynamics of Rull cave (Spain)

Rull cave is a karstic cave located in Vall d’Ebo (Alicante, Southeast of Spain) developed in massive Miocene conglomerates and Cretaceous limestones. Processes in soil above Rull cave and outdoor atmosphere directly influence the underground environment of the cave. Continuous and discrete monitoring of cave atmosphere and soil (from 2012 to 2022) allows to characterise the spatial distribution and temporal variations of the gaseous concentration (222Rn and CO2) and understand the relationship between the processes which occurred in the 3-component system (soil-cave-atmosphere). Besides the presence of visitors, Rull cave maintains stable values of mean temperature (16.2 °C) and relative humidity (97.6%). In an annual cycle the cave presents two different gaseous stages (stagnation and ventilation). Maximum average values of CO2 and 222Rn concentration are reached within the stagnation stage, in the warmest period of the year. On the contrary, in the ventilation stage (in the coldest months) the cave reaches the lowest concentrations in its inner atmosphere. For the study period, daily average CO2 and 222Rn concentrations are 2008 ppm and 1745 Bq/m3, respectively. Results show that the dynamics of 222Rn and CO2 in the cave air follow different patterns defined by the complex relationships between external and internal factors. Findings from this study provide substantial information about the environmental situation of the cave atmosphere in terms of air quality for visitors and workers.

Evaluation of indoor 222Rn and 220Rn concentrations in Dakshina Kannada, Karnataka, India

Naturally occurring radioactive gases which tend to build up (radon and thoron) in indoor environs can cause deleterious health effects including the development of lung cancer. The present study aims to measure 222Rn and 220Rn levels in dwellings in different seasons in the environs of Dakshina Kannada region of India. The 222Rn and 220Rn concentrations were measured in the monsoon, autumn, winter, and summer seasons using Solid State Nuclear Track Detector (SSNTD, LR-115 type II) films fixed in single-entry pinhole cylindrical twin-cup dosimeters. The higher 222Rn levels in indoors were observed during winter with an average concentration of 38.8Bqm-3 and lower during summer with an average of 14.1Bqm-3. The average indoor thoron concentration was also highest in winter with an average value of 25.5Bqm-3 and lowest in summer with 8.8Bqm-3. The annual inhalation dose ranged from 0.44 to 1.06mSvyear-1 with a mean value of 0.66mSvyear-1. The annual effective dose varied from 1.03 to 2.57mSvyear-1 with an average value of 1.59mSvyear-1. The assessed values have been contrasted with the limit suggested by the UNSCEAR and the ICRP and were found to be within the permissible level. The normality of frequency distribution curves of 222Rn and 220Rn concentrations was assessed by the Kolmogorov-Smirnov test.

Annual Effective Dose and Excess Lifetime Cancer Risk due to Ingestion and Inhalation of Radon in Groundwater of Bosso Community Minna, North-Central Nigeria

Radon in potable water has become an issue of public health concern, especially when consumed or used directly from source for domestic purposes without any pre-treatment. In this study, 222Rn concentration in 22 water samples collected from 2 groundwater sources (open wells, 12 samples and boreholes, 10 samples) in Bosso town, North central Nigeria were measured using Durridge RAD-7 radon detector with RAD-H2O accessories. 222Rn concentrations in open wells varied from 2.1±0.7 to 27.9±2.5 Bq L-1 with a mean of 10.2±1.5 Bq L-1, while that in boreholes ranged from 2.8±1.1 to 39.2±1.5 Bq L-1 with a mean value of 14.3±1.7 Bq L-1. These values are lower than the 100 Bq L-1 upper limit proposed by the European Union Commission, above which any practical intervention may be necessary. Mean annual committed effective dose to adults, children and infants from ingestion of water were 74.64, 71.58 and 53.17 \muSv y-1 respectively for the open wells and 104.24, 99.96 and 74.26 \muSv y-1 respectively for borehole water samples. Mean whole body dose due to ingestion and inhalation of waterborne radon from open wells and boreholes are 27.56 and 38.48 \muSv y-1 respectively, which are below the reference level of 0.1 mSv y-1 for potable water recommended by the World Health Organization for public safety. The excess lifetime cancer risk were 0.10 × 10-3 for the open wells and 0.13 × 10-3 for the boreholes, which are lower than the world safety limit 0.29 × 10-3. Water from the two groundwater sources investigated is therefore fit for consumption and other domestic usage from the point of view of radiation protection.

Groundwater as a source of phosphorus and silicate in an estuarine zone: results from continuous monitoring of nutrients and 222Rn

The concentrations of 222Rn and dissolved inorganic nutrients in river water at a fixed station of the Nakdong River estuary which has an artificial barrage were continuously measured from October 2014 to May 2015. Monthly benthic 222Rn flux from the river bottom was estimated using a simple mass balance model, taking into account 222Rn sources and sinks. The estimated benthic 222Rn flux shows a significant correlation with groundwater level, suggesting that groundwater level can be used as a representative of the groundwater input. Based on correlation analyses, the concentration of dissolved inorganic nitrogen (DIN) was found to be dependent primarily on river water input. In contrast, the concentrations of dissolved inorganic phosphorus (DIP) and dissolved inorganic silicate (DSi) were predominantly controlled by groundwater input. Our results suggest that groundwater input may be an important source of DIP, especially under P-limited condition, which can affect marine primary production and ecological problems such as eutrophication and algal blooms in the coastal zones.

Understanding Seasonal Indoor Radon Variability from Data Collected with a LoRa-Enabled IoT Edge Device

The long-term assessment of radon (Rn) is a critical factor in evaluating the exposure risk faced by building occupants, and it plays a significant role in determining the implementation of Rn remediation strategies aimed at enhancing indoor air quality (IAQ). Meteorological parameters, such as temperature, relative humidity, and atmospheric pressure, as well as geological factors, such as soil properties, uranium content, rock formations, parent rock weathering, and water content, can significantly impact the assessment of Rn exposure risk and the selection of appropriate mitigation measures. A continuous monitoring campaign of a National Architectural Heritage building serving as a museum open to the public for a period of 546 consecutive days was conducted. The results of the in situ investigation revealed a broad range of seasonality in indoor Rn emission, with a negative correlation observed between Rn concentration and air temperature. The data indicated that indoor Rn concentration increases in the winter months as a result of reduced indoor air temperature and decreased air exchange, while it decreases in the summer months due to increased air temperature and enhanced natural ventilation. However, the implementation of high ventilation rates to improve IAQ may result in significant heat losses, thereby affecting the thermal comfort of building occupants during the winter months. Therefore, it is imperative to achieve a balance between ventilation practices and energy efficiency requirements to ensure both IAQ and thermal comfort for building occupants.

Developing a radon monitor for simultaneous measurement of Rn-222 and Rn-220 with less influence of humidity based on electrostatic collection and CR-39 detector

Based on electrostatic collection and CR-39, a novel radon monitor (Hynu EIRM-II) was designed to reduce the effect of humidity for simultaneous measurement of Rn-222 and Rn-220 with two 50 mL hemispherical internal cells connected in a serial configuration. A 10 cm tube connects two internal cells to avoid entry of Rn-220 into the second one. While the relative humidity in the internal cell of Hynu EIRM-II is 1% or above 10%, the difference of Po-216 collection efficiency estimated by an improved model is 8.36% at a cell-wall voltage of 2000 V. The simultaneous measurement experiments of Rn-222 and Rn-220 concentrations were performed under three relative humidity ranges of 5%–10%, 80%–88% and 99%–100%. These experimental data show that the maximum differences of the calibration factors for Rn-222 and Rn-220 are 10.13% and 14.42%, respectively. The detection efficiency of Hynu EIRM-II was less affected by humidity. The measurement data of Rn-222 and Rn-220 by the Hynu EIRM-II can provide references for further improvement of radon monitors to accurately measure radon and thoron concentration.

Assessment of Health Risk of Exposure to Alpha-Emitters in Cheese Samples Collected from Iraqi Markets

In this research, alpha-emitter concentrations of 222Rn, 226Ra, and 238U in Iranian, Turkish, Egyptian, Saudi Arabian, and Iraqi canned cheeses that are available in Iraqi markets were measured using the CR-39 detector. Also, the health risk parameters associated with the ingestion of alpha-emitter radionuclides, such as the annual average internal effective dose (AAIED) and the risk of an excess cancer fatality per million persons (RECFPMP), were calculated. The results show that the average values of 222Rn, 226Ra, and 228U concentrations for all samples in the present study were 3.7±0.38 Bq/m3, 25.24±2.63 mBq/kg, and 0.025±0.002 ppm, respectively. The average values of AAIED and RECFPMP were 0.175±0.018 µSv/y and 0.674±0.070, respectively. The results show that the highest value of alpha-emitters as well as health risk parameters were found in cheese samples produced in Saudi Arabia, while the lowest results were found in Egyptian samples. They were, nevertheless, less than the permissible value and the risk value. According to the current study, the consumption of those cheese products poses no health risks.

Influence of advection on the soil gas radon deficit technique for the quantification of LNAPL

The Radon (Rn) deficit technique is a rapid, low-cost, and non-invasive method to identify and quantify light non-aqueous phase liquids (LNAPL) in the soil. LNAPL saturation is typically estimated from Rn deficit using Rn partition coefficients, assuming equilibrium conditions. This work examines the applicability of this method in the presence of local advective fluxes that can be generated by groundwater fluctuations or biodegradation processes in the source zone. To this end, a one-dimensional analytical model was developed to simulate the steady-state diffusive-advective transport of soil gas Rn in the presence of LNAPL. The analytical solution was first validated against an existing numerical model adapted to include advection. Then a series of simulations to study the effect of advection on Rn profiles were carried out. It was found that in high-permeability soils (such as sandy soils), advective phenomena can significantly affect Rn deficit curves in the subsurface compared with those expected, assuming either equilibrium conditions or a diffusion-dominated transport. Namely, in the presence of pressure gradients generated by groundwater fluctuations, applying the traditional Rn deficit technique (assuming equilibrium conditions) can lead to an underestimation of LNAPL saturation. Furthermore, in the presence of methanogenesis processes (e.g., in the case of a fresh LNAPL of petroleum hydrocarbons), local advective fluxes can be expected above the source zone. In such cases, Rn concentrations above the source zone can be higher than those above background areas without advective phenomena, resulting in Rn deficits higher than 1 (i.e., Rn excess), and thus leading to a wrong interpretation regarding the presence of LNAPL in the subsurface if advection is not considered. Overall, the results obtained suggest that advection should be considered in the presence of pressure gradients in the subsurface to ensure an effective application of the soil gas Rn-deficit technique for quantitative estimation of LNAPL saturation.

System upgrade for μBq/m3 level 222Rn concentration measurement

The Jiangmen Underground Neutrino Observatory (JUNO), a 20 kton multipurpose underground liquid scintillator detector, was proposed for the determination of the neutrino mass hierarchy as primary physics goal. The central detector will be submerged in a water Cherenkov detector to lower the background from the environment and cosmic muons. Radon is one of the primary background sources. Nitrogen will be used in several sub-systems, and a highly sensitive radon detector has to be developed to measure its radon concentration. A system has been developed based on 222Rn enrichment of activated carbon and 222Rn detection based on the electrostatic collection. This paper presents the detail of a μBq/m3 level 222Rn concentration measurement system and gives detailed information about how the adsorption coefficient was measured and how the temperature, flow rate, and 222Rn concentration affect the adsorption coefficient.

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.
 Objectives: To find the distribution of radon, thoron and their progeny levels with wall and floor distances.
 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.
 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.
 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.

Long-term vs. short-term measurements in indoor Rn concentration monitoring: Establishing a procedure for assessing exposure potential (RnEP)

Radon (Rn-222 or Rn) is a naturally occurring chemical element that belongs to the progeny of U-238 released from soil and rocks into the atmosphere, whose impact on organisms is not negligible when it occurs inside confined spaces, such as mine shafts or low-ventilated buildings. The current methodologies for indoor radon assessment are based on passive and active detection. If passive detectors are mainly designed for long-term assessment, active detectors are electronic equipment that can allow on-time visualization of results and, therefore, faster decision-making on risk mitigation measures implementation. However, despite offering a prompt and informed decision, the uncertainty associated with active detector results may cast doubt on the quality of the measurements, which especially arises from the duration of the monitoring campaign. Since radon emanation from soils and rocks depends on a set of variables related to meteorological parameters and soil structure, the seasonal variation of these parameters impacts indoor radon concentration assessment, both on short-term and long-term measurements. Therefore, short-term monitoring campaigns lasting a month, a week, or a day may not produce a statistically representative description of indoor radon exposure for the monitored building. Accordingly, the study compares the reliability of short-term and long-term indoor radon measurements. It proposes a procedure for assessing the indoor Radon Exposure Potential (RnEP) based on in situ measurements through the analysis of the frequency of occurrence of results divided into three classes of potential exposure (low, moderate and high) to reduce occupants' radon risk exposure.

Comparative study of radon sources and associated health risk in four underground uranium mines.

This paper presents a comparative study of the quantitative estimation of 222Rn and its health risk from various sources in four underground uranium mines. 222Rn exhalation rates from uranium-bearing rocks and backfill materials were estimated by calculating the 222Rn concentration accumulated in an enclosed chamber into which radon was exhaled. This comparative study indicates a more significant effect of porosity on the exhalation rates. Dissolved 222Rn in mine water was estimated using scintillation cell and bubbler kit. The discrepancy in 222Rn concentration in the mines might be attributed to the variation in geological features, ore grade, and porosity. This study revealed that the maximum radon exposure was produced from the backfill mill tailings, followed by uranium ore and mine water in the mines. The radon dose values in the individual mines remained under the safe dose limit of 20mSvyear-1. The excess lifetime cancer risk (ELCR) and 222Rn-induced lung cancer cases (RnLCC) per million persons per year were also estimated.

222Rn and 226Ra concentrations in selected shallow circulation groundwaters from the Fore-Sudetic Monocline area

Natural radioactive isotopes occur in various components of the natural environment, including groundwater. The general population, not always aware of possible threats, can use its resources. The activity concentration of some of the radioactive isotopes should be monitored, especially in those intakes from which it is possible to obtain water for human consumption, e.g. in domestic wells. The conducted research was innovative due to the fact that in many countries, including Poland, there are no regulations on waters exploited from home wells using as a drinking water source. As the groundwaters from this area have not been examined for radon (222Rn) and radium (226Ra) occurrence yet, the goal of this research was to perform screening tests in this part of the Fore-Sudetic Monocline. For this purpose, the authors have measured the concentration of 222Rn and 226Ra activity in groundwater collected from this geological unit located in south-western Poland. 222Rn and 226Ra occurrence was researched, and specific electrolytic conductivity, redox potential, pH and temperature were measured in 52 groundwater samples. 222Rn activity concentration ranged from 0.18 to 19.78 Bq/dm3. Only in three cases, 226Ra activity concentration reached a value above the lower detection limit of the applied method, i.e. 0.05 Bq/dm3 (max. 0.77 Bq/dm3). The authors present completely new data on the occurrence of these radioactive isotopes in the waters of the first aquifer in the Fore-Sudetic Monocline, which is not without significance for the health of consumers of these waters.

Estimation of Inhalation and Ingestion Dose Due to Radon Concentration in Drinking Water Samples of Shankaraghatta Forest Environment, Karnataka, India

Objectives: To estimate inhalation and ingestion doses due to radon concentration in rural areas of Shankaraghatta forest environment, India. Methods: In this study, the risk due to radon concentration in underground drinking water samples of the Shankaraghatta region has been estimated using emanometry technique. The 44 drinking water samples were collected from different water sources in sample bottles (500 ml) and were carefully sealed to ensure there is no air gap and were analysed within 24 hours by radon bubbler technique using a Lucas cell. Findings: The radon (222Rn) concentration in underground and surface water samples of the entire region varies from 1.10  0.25 Bq l􀀀1 to 30.67  5.10 Bq l􀀀1 with an average value of 13.10  2.2 Bq l􀀀1, is higher than the USEPA proposed maximum contamination threshold of 11Bql􀀀1.The Annual Effective Dose Equivalent (AEDE) ranges from 3.86 mSv y􀀀1 to 83.80 mSv y􀀀1 with an average value of 36.35mSv y􀀀1, which is slightly higher than the global average value. Novelty: The present work focuses on the public health of the study area where such estimation was not carried out. The estimated annual effective, inhalation and ingestion doses due to radon in underground drinking water samples are found to be substantially below the 100 mSvy􀀀1recommended by WHO and EC. Hence, public of the study area won’t receive any serious health hazard due to radon in drinking water and the water is fit for drinking without any additional treatment. Keywords: Radon Concentration; Underground and Surface water; Emanometry Technique

Radiotoxicity and health risk assessment of 222Rn in groundwater using statistical and Monte Carlo simulation approaches

Water is an important natural resource to humans, and itsquality has been a big concern from time immemorial. Water is polluted by the increasing activities of man. Pollutants of major concern include naturally occurring radioactive materials (NORM), heavy and potentially toxic metals, which are ubiquitous in the environment. Naturally occurring radionuclides such as 222Rn are the major precursors of lung and other types of cancer in humans. Exposure to radon in drinking water in excess of 300 pCi/L is treated as a radiological risk, while toxic metals in excess of the World Health Organization (WHO) maximum permissible levels in drinking water are considered both environmental and health risks to humans. A total of 34 groundwater samples were collected in the Akoko area of Ondo State, Nigeria for 222Rn activity concentration determination. The water samples were collected using standard techniques. RAD7 solid-state-detector was utilized for the 222Rn measurements. The results show the activity concentration of 222Rn ranging from 76 pCi/L to 3593 pCi/L with a mean value of 705 ± 76 pCi/L. Inhalation and ingestion doses from 222Rn dissolved in groundwater were evaluated for the infants, children, and adult populations in the study area. Radiological risks were evaluated through statistical and Monte Carlos simulation methods. It can be concluded from this study that there exists a likelihood of radiation-induced health risks due to inhalation of 222Rn from the sampled water.

Application of FSVD Algorithm to Airborne Gamma Detection of Trace Radionuclides in the Process of a High Radon Background

We address the performance of airborne gamma detection systems equipped with a NaI(Tl) detector to monitor radionuclides in specific areas. In particular, we analyze the use of the fast singular value decomposition (FSVD) algorithm to improve the nuclide recognition ability of the system and effectively trace radioactivity in a complex background environment. We first present a theoretical analysis of the FSVD algorithm and illustrate the nuclide recognition algorithm step by step. The core of the algorithm is singular value decomposition and parameter estimation based on a Gaussian Markov linear regression model. From the estimated values of the parameters, information about radionuclides can be effectively extracted. We assume the presence of a strong background due to a high concentration of 222Rn and its progeny, which is simulated using GEANT4. By adding trace elements of 131I and 137Cs and changing the relative emissivity, the ratio of the total energy peak count of 131I and 137Cs to the background environment interval count of the corresponding 222Rn and its progeny are controlled. Assuming a counting ratio equal to 0.005, the FSVD algorithm is still able to effectively discriminate the presence of a small number of nuclides, reflecting very excellent recognition ability. Finally, based on data from an airborne gamma detection system in a self-control radon chamber, the FSVD algorithm is employed to recognize the trace of 137Cs nuclides in a strong radon background. A DURRIDGE RAD7 radon measuring instrument is used to monitor the radon concentration in the radon chamber. The actual measurement results show that the FSVD algorithm can effectively detect 137Cs nuclides.