Continuous Radon Monitoring Research Articles

International intercomparison of Radon 222 activity concentration calibration facilities

The Coalition of International Radon Associations (COIRA) organised an inter-comparison of Rn-222 (radon) activity concentrations reported by calibration laboratories. A set of three AlphaGUARDs were used as transfer reference instruments against which to compare reported Rn-222 activity concentrations. Rn-222 activity concentration calibration facilities (sometimes termed chambers) from seven countries (Australia, US, Czech Republic, Spain, England, Sweden, Canada), and three continents participated in this project. The objective of the study was to provide information useful to calibration chamber operators and public health officials in the improvement of measurement and control systems, the maintenance of performance standards for measurements, and regulatory requirements for calibrations. This work builds upon and expands previous interlaboratory comparisons and provides data for estimating and using calibration uncertainty values as part of overall field error estimates and limits. A simple proportional difference between laboratories is presented here, calculated as the average for N hours of each hour’s difference between the laboratory’s concentration and the average of the three reference instruments. This percent difference ranged from less than 0.5% to just less than 8%. This work demonstrates that the ANSI/AARST standards limit of 8% for the estimated unexpanded (one sigma) individual calibration estimated uncertainty for continuous radon monitor calibration facilities in the US is achievable. However, given the few standards regarding calibration of Rn-222 activity concentration measurement instruments that themselves are often used to calibrate secondary and tertiary Rn-222 calibration facilities, there is a great need for continued interlaboratory comparisons to harmonise and document the calibration of Rn-222 activity concentrations.

Applied experimental research on in-situ online monitoring instrument for soil radon in fault zone

As an emerging method for seismic precursory signals in underground fluid, the reliability and stability of in-situ online monitoring devices for soil radon are crucial performance indicators that are directly related to the successful implementation of continuous monitoring of soil radon in seismic areas. This study conducted laboratory testing and field applications of a new in-situ online monitoring instrument for seismic soil radon, utilizing the experimental testing conditions provided by the radon monitoring instrument detection platform of the China Earthquake Administration and the natural experimental site at Xianshuihe Fault Zone in the China Seismic Experimental Site. The results indicate that laboratory measurement repeatability of the instrument is 5.53%, the relative intrinsic error of radon volume response activity is 1.53%, and the response capability of hourly sampling at high radon volume response activity (greater than 1.0 × 105 Bq/m3) lags behind the standard instrument by 2 h, essentially meeting the requirements for seismic observation. Under field conditions, the instruments exhibit good synchronization in response at different depths at the same location. However, further improvements are needed to enhance the consistency of long-term operation in the field, as well as the adaptability to outdoor self-powering, data transmission, and environmental conditions.

Characteristic parameters and radon exhalation rates of aerated concrete blocks

ObjectiveTo understand the characteristic parameters and radon exhalation rates of aerated concrete blocks. MethodsA total of 39 nationally inspected samples were measured. Their dry density was determined based on their mass and volumes, their porosities were measured on the principle of volumetric expansion, and their radium content was determined using a high-purity germanium (HPGe) detector for gamma-ray spectroscopy. Furthermore, their diffusion lengths were quantified by establishing a combined cumulative and diffusion chamber, and their radon exhalation rates were measured through closed-box testing using a continuous radon monitor. ResultsThe aerated concrete blocks exhibited dry densities ranging from 464 to 840 ​kg/m3 [average: (654.0 ​± ​82.5) kg/m3], open porosities from 67.1 ​% to 81.1 % [average: (74.3 ​± ​3.3) %, radium (226Ra) content from 12.3 to 136 Bq/kg [average: (63.0 ​± ​30.4) Bq/kg], diffusion lengths from 0.49 to 1.01 ​m [average: (0.70 ​± ​0.15) m], and radon exhalation rates from 0.6 to 22.8 Bq·m−2·h−1 [average: (7.3 ​± ​5.3) Bq·m−2·h−1]. ConclusionAerated concrete blocks exhibit significantly higher porosities, diffusion lengths, and radon exhalation rates than traditional concrete and clay bricks. These blocks might contribute to the high indoor radon concentration observed in modern buildings in China.

Study of the filtration efficiency of radon progeny in facial masks

Radon exposure is the second-leading environmental cause of lung cancer, therefore finding ways to reduce the radon inhalation dose is a priority objective. Inhalation dose is calculated considering two contributions, the radon gas on the one hand and its progeny on the other. This paper studies the effectiveness of face masks (surgical masks, FFP2 and FFP3) to reduce the contribution of radon descendants that pass into the respiratory tract and thus reduce associated inhalation doses. To analyze the radon filtering potential of these masks, a continuous radon monitor has been used to estimate the radon concentration and the Potential Alpha Energy Concentration with and without facial masks. The data registered by this monitor, together with an error minimization algorithm developed in Matlab®, allow the Equilibrium Equivalent Concentration to be calculated. These results make it possible to compare the inhalation doses received by a person not wearing or wearing different types of masks, obtaining a dose reduction of 64% for surgical masks compared to the study without mask, a reduction of 71% for FFP2 and 72% for FFP3 masks.

R Radiological Risk Assessment Of 222 Radon Concentration And Annual Effective Dose Calculation In Groundwater From Zakho, Iraq

Radon, the heaviest of noble gases in the periodic table, is a naturally occurring radioactive nuclide found in rocks, soil, and water. It has gained increasing attention in recent research due to its association with cancer. This study focused on assessing the potential radioactive risks associated with water usage in Zakho, Iraq, by analyzing 16 groundwater samples collected from the primary water source. Alpha spectrometry with RAD7 and RAD-H2O accessories from Durridge CO was employed for assay purposes. The measured 222Rn concentrations ranged from 0.21 ± 0.1 to 19.75 ± 4.8 BqL−1, with an average of 8.90 Bq. −1. The recorded values indicate that 31% of the data surpasses the specified United States Environmental Protection Agency (USEPA) limit of 11.1 BqL−1. Notably, the evaluation of the total annual effective dose revealed significant age-related variations. Specifically, 62% of infant samples and 68% of children samples exceeded the acceptable limit of 100 μSv/y, while 25% of adult samples surpassed the World Health Organization (WHO) recommended threshold. The obtained data align with similar studies conducted globally, emphasizing the need for continuous radon monitoring during water consumption. The findings advocate for proactive measures to ensure the safety of these water sources, addressing the pressing concern of radon-related health risks.

Indoor radon concentration levels in some selected offices at Ibrahim Badamasi Babangida University, Lapai, Nigeria and its attendant annual effective dose

Although radon concentrations in outdoor environments are generally low, the indoor concentrations can become appreciably high thereby affecting the indoor air quality and causing some severe health challenges. Thirty (30) offices from the ground floor and first floor of some buildings within Ibrahim Badamasi Babangida (IBB) University campus, Lapai Nigeria, were randomly selected for indoor radon concentration (CRn) measurement using RAD7 continuous radon monitor. Annual effective dose was also computed to determine the level of public exposure. The results showed that radon concentration values for all the offices on the ground floor ranged between 9.6±2.7 Bqm−3 and 90.7±8.1 Bqm−3, with mean value of 28.5±4.8 Bqm−3 while the range of radon concentration at first floor was 2.5±1.4 Bqm−3 - 80.4±7.5 Bqm−3. All the measured indoor radon concentration levels were less than the 100 Bqm−3 action level proposed by World Health Organization (WHO). Average annual absorbed dose for both ground and first floors were 0.36±0.06 mSvy−1 and 0.24±0.05 mSvy−1 respectively, with corresponding mean annual effective dose of 0.86±0.15 mSvy−1 and 0.58±0.11 mSvy−1 in sequence. These values were below the 1.0 mSvy−1 safety limit set for public. Although the results did not suggest any immediate exposure threat to the public, it is important that the University staffs are adequately informed of indoor radon levels and its attendant health hazards. Improved and adequate ventilation of all the office buildings is highly encouraged in order to keep the radon levels as low as reasonably achievable (ALARA).

Radon Flux Measurement System.

Disposal of naturally occurring radioactive material (NORM) and technologically enhanced naturally occurring radioactive material (TENORM) waste in the State of Oregon is prohibited unless it can be demonstrated that the material is nonradioactive as defined by its radionuclide content and potential for emission into the environment. It was determined that a radon flux on the surface of the waste no greater than 0.37 Bq m -2 s -1 would meet this requirement. This article provides a method to estimate the radon flux through indirect measurement of the radon mass exhalation rate. It describes a device that consists of a radon accumulation chamber coupled with a continuous radon monitor and software to process the results and calculate the radon mass exhalation rate and radon flux for an unknown sample of approximately 500 g. The chamber system was tested with a uranium ore sample.

Extreme reverse seasonal variations of indoor radon concentration and possible implications on some measurement protocols and remedial strategies

Indoor radon levels in dwellings are typically higher in cold months than in warm ones. The indoor radon concentration might experience an inverse seasonal behaviour – i.e., radon levels much higher in summer than in winter – under specific circumstances.In the framework of a study on long-term variations of annual radon concentration carried out in some tens of dwellings in Rome and surrounding small towns, two dwellings with very high – up to extreme – reverse seasonal variations were accidently discovered. These dwellings were located in a volcanic area, and they are both south-oriented and located on the lower part of a hill.In one of them, radon concentration was monitored by a continuous radon monitor for two years to find out when the greatest rises in radon levels occur. The indoor radon concentration resulted to experience extremely rapid, i.e. very few hours, increases up to 20 000 Bq m−3 during the spring period (i.e., April, May, and June especially). After about ten years from the first observation, the indoor radon concentration of the same house was monitored again for about five years: radon concentration peaks previously observed were found to be unchanged in terms of absolute values, duration, rising time and occurrence period.These reverse seasonal variations may lead to significant underestimation of the actual annual average radon concentration in case of measurements lasting less than one year if performed during the cold season and especially when seasonal correction factors are used. Moreover, these results suggest adopting specific measurement protocol and remediation strategies in houses having some peculiar characteristics, mainly regarding orientation, position, and attachment to the ground.

Study of the performance and time response of the RadonEye Plus2 continuous radon monitor

The availability of affordable continuous radon monitors opens new opportunities for studying the temporal variations of indoor radon and for more precise exposure estimates based on the actual hours spent in homes and workplaces. These new applications require tests of the monitors characteristics, including their response time. A study of a promising electronic radon monitor with high sensitivity, the RadonEye Plus2, was conducted. It was found that it has excellent linearity up to 3500 Bq/m3. A slight deviation from linearity within 12% was observed in the range 3500–7000 Bq/m3. The reproducibility of measurements with 36 different RadonEye monitors was within 7%, estimated in the range of linearity.A dedicated procedure for time response characterization was developed based on exposure to rectangular activity concentration pulses (spikes). It was applied to the RadonEye and three other commercial monitors. The determined characteristic response times of the RadonEye monitor are about 40 min for reaching 50% of the plateau of a rectangular pulse and 90 min for reaching 90%. They are somewhat higher than the corresponding response times of the AlphaE monitor, which are 20 and 60 min, respectively. The response times of the RAD7 monitor in sniff mode are about 3 min for reaching 50% of the plateau and 10 min for reaching 90%. The AlphaGUARD monitor in flow-through mode has the fastest response — it reaches 95% of the plateau in less than 2 min. The monitor AlphaGUARD PQ2000 Pro Rn/Tn is therefore recommended for follow-up of the activity concentration in time response studies of other monitors. It is demonstrated that by exposure to spikes the response function of a monitor can be obtained and used to model its response to variable concentrations.Overall, the RadonEye’s response is sufficiently fast to follow radon variations even in buildings with active ventilation. This sensitive monitor is suitable for homes and workplaces and can be helpful in the installation and investigation of radon mitigation systems and in studies of the indoor radon dynamics.

Recent work with electronic radon detectors for continuous Radon-222 monitoring

Background: Sensitive electronic radon detectors can be an advantageous solution for continuous monitoring of radon dynamics in dwellings and workplaces. In order to investigate their applicability, such detectors must be subjected to adequate metrological assurance, and their performance in field conditions must be tested and evaluated.
 Objectives: To perform laboratory and field tests in order to evaluate the applicability of RadonEye+2 instruments for continuous radon monitoring.
 Results: In this work, we have performed laboratory tests of 36 RadonEye+2 detectors, which appear to have linear response for 222Rn concentrations below 3.5 kBq/m3 and a non-linear response (<15%) in the interval from 3.5 to 7 kBq/m3. Their response to 222Rn at 4.7 kBq/m3 is within 15% to the reference. In experiments with sharp variation of the 222Rn concentration, the detectors show fast response within 2 h. For the application of the detectors in dwellings and workplaces, we have developed a database, which collects, stores and visualises the RadonEye data. The database proved to be very useful tool, not only for data analysis but also for the identification of interruptions in the detectors operation and/or their connection to the internet. In a pilot 10-month-long study with three detectors located in different dwellings, we have observed more than 91% uptime of the online data collection from the detectors and more than 96% uptime of the data recording in the internal memory of the instruments.
 Conclusions: Overall, the results show that the RadonEye+2 instruments are very suitable for continuous radon monitoring and may be useful for follow-up of radon dynamics in long-term measurement campaigns in homes and workplaces.

Further refinements of a continuous radon monitor for surface ocean water measurements

Radon is an excellent natural tracer for studying various geophysical processes. In the past centuries, radon isotopes measurement approaches for marine research have been fully developed but still suffer limitations. Here we present the setup and validation of an improved continuous online measurement system (PIC-ORn) to measure dissolved radon in the surface ocean and other water bodies. We demonstrated that the PIC measurement efficiency is ~2 times higher than a RAD7 and is less affected by relative humidity and produces reliable results. Laboratorial measurements indicated that the new PIC-ORn system responded timely to the change of radon activities in water. The new system was successfully deployed during a cruise to the northwest Pacific Ocean in June 2021. Despite low radon-in-water activities, the results obtained by the new PIC-ORn system matched the traditional measurement systems within the estimated uncertainties. The PIC-ORn detector takes advantage of higher efficiency, lower cost, and power consumption, and is less affected by air moisture. The new system does not rely on drying units, further reducing on-site supervision, which would benefit the researches in submarine groundwater advection and diffusion and ocean-atmosphere gas exchange.

INFLUENCE OF SAMPLING FLOW RATE ON THORON EXHALATION RATE MEASUREMENTS BY THE CIRCULATION METHOD.

Researchers have used various methods to obtain the exhalation rates of radon and thoron from soil and building materials. One of the typical methods for radon exhalation rate is the circulation method using an accumulation container, an external or internal sampling pump and a continuous radon monitor. However, it is necessary to consider sampling flow rate if this method is applied to exhalation rate measurement for thoron due to its short half-life. Based on a calibration experiment, the measured thoron concentrations obtained by an electrostatic collection type radon and thoron monitor (RAD7) were found to be influenced strongly by the sampling flow rate. It was also found that the thoron exhalation rate from a soil sample depended on the pressure difference which was proportional to the increasing sampling flow rate. The thoron exhalation rate measured at the generally used sampling flow rate of the internal sampling pump of the RAD7 was overestimated compared with the value at 0 L min-1.

Assessing the need for radiation protection measures in artisanal and small scale mining of tantalite in Oke-Ogun, Oyo State, Nigeria

There is concern that work scenarios on the tantalite mining sites in Oke-Ogun, Oyo State, Nigeria may cause occupational radiation exposure of workers due to enhanced concentrations of naturally occurring radionuclides in some process materials. A prior radiological assessment of the mining activities was carried out to determine if and which exposure scenarios may require radiation protection measures. Samples of the materials involved, comprising tantalite (tantalum ores), soil and waste rock were collected and analyzed for activity concentrations of 40K, 226Ra, 238U and 232Th using a hyper pure germanium detector gamma-ray spectrometer. Radon concentrations in the mines were also measured using a continuous radon monitor - Radon-Scout Plus (Sarad, GmbH). Activity concentrations of 40K are below 10 Bqg-1 in all the samples but all the tantalite samples contain more than 1 Bqg-1 of 226Ra and 238U. Hence tantalite is regarded as naturally occurring radioactive material (NORM) and the mining activity as a practice. The requirements for planned exposure situations apply to all the mining sites but, on the basis of graded approach, the optimum radiation protection measures vary from one mine to another, ranging from exemption to authorization. Exposures to radon in the underground mines pose the greatest radiological risks and portend the greatest need for regulatory control in the mining operations. The results further underscore the need to integrate radiation protection with the other health and safety measures in the mining sector.

Multi-level continuous monitoring of indoor radon activity

We present the results of an experiment taking place inside the geophysical museum of Rocca di Papa (Rome, Italy), where the high radon levels detected might pose a risk to the health of workers and of the public audience. As a first step towards the mitigation of potential exposure risk, four active sensors were installed at different floors of the building, in order to continuously monitor not only radon exhalation from the soil but also its transport from the ground up to elevated floors. Collecting more than three years of data of radon concentration enables us to identify fluctuations over both short and seasonal scales and to elucidate the relation between radon variations and changes of internal temperature and relative humidity. The analysis of such dataset reveals how the healthiness of indoor environments in terms of radon concentration is controlled by a number of factors, including the environmental conditions and the use of heating and ventilation systems. Finally, the continuous radon monitoring at different levels of the building provides a unique chance to trace the vertical radon diffusion, allowing to make a first-order estimate of upward radon velocity.

Use of Radon and CO2 for the Identification and Analysis of Short-Term Fluctuations in the Ventilation of the Polychrome Room Inside the Altamira Cave.

A study is presented on rapid episodes of air exchange in the Polychrome Room of the Altamira Cave (Cantabria, Spain) using continuous monitoring of radon and CO2 tracer gases, as well as environmental parameters such as internal and external air temperature. For this, criteria have been developed to carry out an inventory of these types of events during the 2015–2020 period. Most of the degassing-recharging events occur over several hours or days, especially during spring and autumn. This means that the room can be significantly ventilated during these short periods of time, posing an exchange of energy and matter with potential impact in the preservation of the rock art present inside. In addition, the hypothesis that temperature gradients between the internal and external atmosphere is one of the main factors that induces degassing has been tested. To this end, correlation analysis has been carried out between the different magnitudes involved in this study, such as radon and CO2 concentrations, and air temperature gradients. A total of 37 degassing-recharging events have been analyzed for the 5 year studied period. The distribution of the duration of the events have been described, as well as that of the correlations between the degassing and recharge stages of each event, showing significant values of r coefficients for the correlation with temperature gradients between the internal and external atmosphere.

Radon concentration measurement and effective dose assessment in drinking groundwater for the adult population in the surrounding area of a thermal power plant

Radon in the household water collected from hand pumps is measured using a continuous radon monitor. Water samples are collected from 25 villages from the surrounding regions of the National Capital Power Cooperation (NTPC), Dadri. The radon concentration ranges from 17±1 to 68±3 Bql-1 with a mean value of 33±13 Bql-1. The measured radon concentration in all collected samples lies well within the limit of 100 Bql-1as set by the World Health Organization (WHO). The mean values of the annual effective dose due to ingestion of radon and due to the inhalation of radon released from water are 84±33 and 167±65 μSvy-1, respectively. In addition, the mean values of estimated total annual effective doses are found to be 167±65 μSvy-1. The mean value of total annual effective doses is found to be higher than the reference dose level of 100 μSvy-1 recommended by the WHO and the United Nations Scientific Committee on the Effect of Atomic Radiation (UNSCEAR). The mean values of effective doses per annum to the lungs and stomach are 9.9±3.9 and 10.1±3.9 μSv, respectively.

Radon in Indoor Air: Towards Continuous Monitoring

Radon poses significant health risks. Thus, the continuous monitoring of radon concentrations in buildings’ indoor air is relevant, particularly in schools. Low-cost sensors devices are emerging as promising technologies, although their reliability is still unknown. Therefore, this is the first study aiming to evaluate the performance of low-cost sensors devices for short-term continuous radon monitoring in the indoor air of nursery and primary school buildings. Five classrooms of different age groups (infants, pre-schoolers and primary school children) were selected from one nursery and one primary school in Porto (Portugal). Radon indoor concentrations were continuously monitored using one reference instrument (Radim 5B) and three commercially available low-cost sensors devices (Airthings Wave and RandonEye: RD200 and RD200P2) for short-term sampling (2–4 consecutive days) in each studied classroom. Radon concentrations were in accordance with the typical profiles found in other studies (higher on weekends and non-occupancy periods than on occupancy). Both RadonEye low-cost sensors devices presented similar profiles with Radim 5B and good performance indices (R2 reaching 0.961), while the Airthings Wave behavior was quite different. These results seem to indicate that the RadonEye low-cost sensors devices studied can be used in short-term radon monitoring, being promising tools for actively reducing indoor radon concentrations.

RADON-222 CONCENTRATION IN AIR: A CASE STUDY OF AYEDUASE TOWNSHIP, KUMASI, GHANA

Objective: Radon levels in structures (interior environment) were measured in many dwellings and hostels in Ayeduase Township, Ashanti Region, Ghana. The purpose of this study was to quantify radon toxicity in the Ayeduase community, which houses approximately half of the students at Kwame Nkrumah University of Science and Technology (KNUST), Kumasi, and to determine the risk levels for individuals (categorized as infants, children, and adults) living in the community's various suburbs.
 Materials and Methods: Households in Ayeduase had an average of four people per room. The radon in air concentration was measured with a continuous radon monitor using continuous active sampling approach. Multiple measurements were taken at tight space-time intervals over a period of 24 hours. The Continuous Radon Monitor was installed in dwelling rooms in zones where the monitor could record fresh air entering the room. The yearly effective dose was computed using the Mondal 3 Software.
 Results: The continuous sample air radon concentration in Ayeduase Township was found to be in the range of 8.510 0.05607 Bq/m3 to 11.100 0.6379 Bq/m3. The manually computed effective annual dose rate for indoor air radon was 0.3494 mSv/year to 0.4558 mSv/year for babies, 0.0683 mSv/year to 0.0891 mSv/year for children, and 0.0559 mSv/year to 0.0729 mSv/year for adults. The comparative results from the Mondal 3 Software showed that the effective annual dose rate for indoor air ranged from 0.32 mSv/year to 0.37 mSv/year, with an average of 0.36 mSv/year for infants, 0.11 mSv/year to 0.14 mSv/year, with an average of 0.12 mSv/year for children, and 0.084 mSv/year to 0.097 mSv/year, with an average of 0.94 mSv/year for adults.
 Conclusion: Ayeduase's radon toxicity profile in terms of air showed distinct features. The maximum value of indoor air radon concentration level determined was lower than the global average value of 40 Bq/m3 of indoor radon concentration level and also lower than the reference level of 100 Bq/m3. In Ayeduase, the estimated average effective dosage over a year for babies, children, and adults were lower than the 1.2 mSv/year indicated by ICRP Publication 126.
 Recommendation: Radon toxicity due to water and soil sources are required to access the total toxicity levels in the township. Reliable evaluation of the potential for human exposure to radon depends in part on the reliability of supporting analytical data from environmental samples and biological specimens is highly recommended, as well as, concentrations of radon in unpolluted atmospheres and in pristine surface waters are typically within the limits of current analytical methods.

Development of high-sensitivity radon detector in water for neutrino physics

The contamination of radon (222Rn) originated from the decay chain of the uranium series in water could be serious background source in underground particle physics experiments. We have been developing a system for continuous monitoring of radon in water. We developed a new high-sensitivity radon detector for water by combining an existing high-sensitivity 80 L radon detector for air and membrane degasifier module used for previous version of radon detector for water. The housing component for membrane degasifier has been improved. The background level of the new radon detector for water was measured and it was reduced by approximately half compared to the previous one.

A continuous radon monitoring system for integration into the climate change observation network

A continuous radon monitoring system for integration into the climate change observation network