Method to Measure Indoor Radon Concentration in an Open Volume with Geiger-Mueller Counters: Analysis from First Principles

A simple method employing a pair of pancake-style Geiger-Mueller (GM) counters for quantitative measurement of radon activity concentration (activity per unit volume) is described and demonstrated. The use of two GM counters, together with the basic theory derived in this paper, permit the detection of alpha particles from decay of and progeny ( 218Po, 214Po) and the conversion of the alpha count rate into a radon concentration. A unique feature of this method, in comparison with standard methodologies to measure radon concentration, is the absence of a fixed control volume. Advantages afforded by the reported GM method include: 1) it provides a direct in-situ value of radon level, thereby eliminating the need to send samples to an external testing laboratory;2) it can be applied to monitoring radon levels exhibiting wide short-term variability;3) it can yield short-term measurements of comparable accuracy and equivalent or higher precision than a commercial radon monitor sampling by passive diffusion;4) it yields long-term measurements statistically equivalent to commercial radon monitors;5) it uses the most commonly employed, overall least expensive, and most easily operated type of nuclear instrumentation. As such, the method is par-ticularly suitable for use by researchers, public health personnel, and home dwellers who prefer to monitor indoor radon levels themselves. The results of a consecutive 30-day sequence of 24 hour mean radon measurements by the proposed GM method and a commercial state-of-the-art radon monitor certified for radon testing are compared.

Monitoring and Evaluation on Indoor Radon Concentration in a District of Xi'an

[Objective] The research aimed to monitor and evaluate indoor radon concentration in one district of Xi＇an City. r Method] In order to master the effective dose per year caused by natural radiation to local residents, the investigation about the level of indoor radon in one district of Xi＇an was developed. Based on the proper monitoring scheme, some typical living rooms were sampled. Through the measurement result, the effects of different factors on radon concentration were obtained. Finally, the radon concentration was transferred into the effective dose per year of local residents. [ Result] Indoor radon concentration in the district was during 49.680 -128.856 Bq/m3, and average concentration in each building was within 100 Bq/m3, which belonged to normal range. When sunny day became rainy day, radon concentration firstly had a rise trend. If continuous rainy weather appeared, indoor radon concentration gradually declined. When other conditions were same, indoor radon concentration under window closing was significantly higher than that under window opening. Indoor radon concentration had a decline trend from 13：00 to 20：00 and a rise trend from 01：00 to 06：00. Condusion The district belonged to radon safety house. To protect residents＇ health to the maximum extent, according to transfer change rule of the radon, window should be opened to ventilate in the morning when radon concentration was higher.

Assessment of Indoor Radon Concentrations in Dwellings for Baghdad Governorate by Using RAD-7 Detector

In the present work, radon gas concentrations in different dwellings in Baghdad governorate are measured by using RAD-7 detector. The results have shown that, the radon gas concentrations ranged between (40.67 ± 3.1 Bq/m3) to (190.00 ± 2.7 Bq/m3) with an average value (113.66 ± 30.2 Bq/m3);in the first one we draw the map radiations for indoor radon gas concentrations in Baghdad governorate. We would like to mention that the present study is considered to be very important and vital because it is concerned with people health and safety in the first place.

A pilot survey on indoor radon concentration in Beijing

Objective:To explore the level of indoor radon concentration especially after recent 3 decades’great economic development in metropolis Beijing,so as to describe the outline of indoor radon level in Beijing.Methods:A one-year integrated measurement on 800 dwellings was carried out from September 2018 to August 2019.Passive integrated radon cup monitor with CR-39 as an alpha-track detector was adopted for the survey.As a pilot study,measurement scheme was designed in detail.For measurement quality control,the background track density of CR-39 was strictly defined and controlled throughout the operation of the survey.Results:The annual geometric and arithmetic mean of radon concentration of the surveyed are(39.3±12.9)and(42.0±13.7)Bq/m^(3),respectively,varying from(12.1±2.5)to(119.0±7.8)Bq/m^(3).Radon concentration of the ground floor dwellings is obviously higher than that of other floors.No difference of radon level is found among the dwellings of other floors.Higher radon concentration in buildings built after 2010 is obtained compared with buildings built in 1980s,1990s,and 2000s.Conclusions:There is no big change of radon concentration level in dwellings in Beijing area observed in general compared with a previous survey performed more than ten years ago.For high-rise buildings,building materials are suggested to be the main source of indoor radon.For higher radon concentration in buildings built in latest ten years,the change on building materials and indoor ventilation rate are thought to be the causes,further study in detail is needed to clarify.

Radon (²²²Rn) Concentration in Fresh and Processed Coconut Water Using a RAD7 Detector

Coconut water has several uses that are beneficial to humans, mainly because of its nutritional and medicinal properties. In this study coconut water samples were collected from the fresh mature coconuts and from packaged processed coconut water to measure the radon concentrations in them. The results were used to estimate the annual effective radiation dose to the general adult population from ingestion of coconut water. The samples were analyzed for radon concentrations using the Durridge RAD-7 radon detector. The results of measured radon concentrations for the fresh mature coconut were ranged from 381.10 Bq·m-3 to 1716.80 Bq·m-3. The results for packaged processed coconut samples ranged from 68.08 Bq·m-3 to 556.85 Bq·m-3. The mean values for the samples were (1081.40 and 222.78) Bq·m-3 for the fresh and processed samples, respectively. The estimated mean annual effective doses (AED) due to ingestion of coconut water were 0.41 and 0.08 μSv·y-1 for fresh and processed samples, respectively. These values are significantly lower than the safe limits recommended by the World Health Organization and the European Commission of 0.1 mSv·y-1 and the maximum contamination level (MCL) of 11,000 Bq·m-3 by the United States Environmental Protection Agency and so do not constitute a risk to consumers of coconut water.

Daily variation of radon gas and its short-lived progeny concentration near ground level and estimation of aerosol residence time

Atmospheric concentrations of radon（^（222）Rn） gas and its short-lived progenies^（218）Po,^（214）Pb, and^（214）Po were continuously monitored every four hours at the ground level in Jeddah city, Kingdom of Saudi Arabia. The measurements were performed three times every week, starting from November 2014 to October 2015. A method of electrostatic precipitation of positively charged^（218）Po and ^（214）Po by a positive voltage was applied for determining^（222）Rn gas concentration. The short-lived^（222）Rn progeny concentration was determined by using a filter holder connected with the alpha-spectrometric technique. The meteorological parameters（relative air humidity, air temperature, and wind speed） were determined during the measurements of^（222）Rn and its progeny concentrations.^（222）Rn gas as well as its short-lived progeny concentration display a daily and seasonal variation with high values in the night and early morning hours as compared to low values at noon and in the afternoon. The observed monthly atmospheric concentrations showed a seasonal trend with the highest values in the autumn/winter season and the lowest values in the spring/summer season. Moreover, and in parallel with alphaspectrometric measurements, a single filter-holder was used to collect air samples. The deposited activities of^（214）Pb and the long-lived^（222）Rn daughter ^（210）Pb on the filter were measured with the gamma spectrometric technique. The measured activity concentrations of^（214）Pb by both techniques were found to be relatively equal largely. The highest mean seasonally activity concentrations of ^（210）Pb were observed in the autumn/winter season while the lowest mean were observed in the spring/summer season. The mean residence time（MRT） of aerosol particles in the atmospheric air could be estimated from the activity ratios of ^（210）Pb/^（214）Pb.

Preliminary Studies on ²²²Rn Concentration in Groundwater of Yaounde, Cameroon

This work presents a preliminary study on groundwater samples carried out from selected groundwaters of some localities of Yaounde, Cameroon. Radon concentration was ranged from 0.11 Bq∙l-1 to 1 Bq∙l-1, with an average of 0.48 Bq∙l-1. The comparison between the physico-chemical parameters and the radon concentrations in groundwater showed a good correlation between these radon concentrations and the values of Electroconductivity (EC). The annual effective dose due to ingestion of radon in water ranged from 0.30 μSv∙y-1 to 7.90 μSv∙y-1 with an average of 1.93 μSv∙y-1. The obtained results of this study were shown that the concentrations of radon in groundwaters and annual effective doses due to ingestion of this groundwater were below the references recommended by WHO.

Comparative Alpha Tracks Counting Using an Optical Microscope and a Spark Counter

In the metrology of radon, an environmental lung carcinogen, the integrated measurements necessary for epidemiological studies are made very often using the tracks detector LR 115 type 2. For dosimetric analysis, the etched tracks from radon alpha particles on this detector are usually counted by means of an optical microscope or a spark counter. An optimal reading of the track densities which must be converted into radon concentrations, can’t be done without a good mastery of the mode of operation and use of these devices. Furthermore, investigations to know as to whether or not each of those can be used to determine radon concentration are necessary. These are the objectives of the present work in which LR 115 samples exposed to radon for at least 3 months, were chemically developed under standard conditions and read. The track densities obtained with the microscope are very much higher than those of the counter for each sample. These results are consistent with those published by other authors. However, each of these devices can be used interchangeably for alpha tracks counting, as both provide radon concentrations with a very good linear correlation coefficient of 0.95 taking into account their respective calibration factors for the reading of this detector. In addition, the saturation phenomenon for the spark counter reading of LR 115 detector occurs beyond 11,000 tr/cm2, a density never reached during our environmental radon measurements.

Effect of Radioactive Minerals Potentiality and Primordial Nuclei Distribution on Radiation Exposure Levels within Muscovite Granite, Wadi Nugrus, Southeastern Desert, Egypt

The studied area at Wadi Nugrus, Southeastern Desert, Egypt, is located between lat. 24°41'00'' and 24°41'35''N and long. 34°36'47'' and 34°37'09''E. The rock types are represented by layered metagabbros, biotite schists, gneisses, granodiorites, and Muscovite granites. The muscovite granite of Wadi Nugrus, is small exposure in size (~5.0 km2), emplaced along NW-SE trend, with about 0.5 - 4.5 Km in length and 100 - 250 m in width and intruding the biotite schists. The studied muscovite granite is composed mainly of plagioclases, potash feldspars, quartz, biotite and muscovite. The recorded minerals assemblage can be classified into secondary U-minerals (uranophane and meta-autunite), U-bearing minerals (uranothorite and columbite) and accessory minerals (zircon, flourite, allanite, zinnwaldite and hematite). The U/eU is more unity where, the measured chemical uranium is higher than the measured equivalent uranium in the most analyzed samples especially in trenches, which reflect disequilibrium state. The activity concentrations range from 251.72 to 1096.2 Bq·kg-1 for 232Th, from 494 to 2593.5 Bq·kg-1 for 226Ra, and from 1314.6 to 1846.7 Bq·kg-1 for 40K. The obtained radiological data show that the average internal and external hazard indices are 9.11 and 5.78, respectively which are more than unity and highly exceeding the permissible limits (International Commission on Radiation Protection, ICRP). The internal and external hazards are mainly due to 226Ra nuclei while the absorbed dose rate (nGy/h) is related to 232Th nuclei. The contributions of the three nuclei in the total absorbed dose rates and internal and external hazardous, for 226Ra, it contributes by 72% in Hin, 57% in Hex and 55% of DR, for 232Th it contributes by 24% in Hin, 37% in Hex and 36.9% of DR, while for 40K it contributes by 4.1% in Hin, 6.4% in Hex and 8.1% of DR.

Annual Committed Effective Dose from Various Phytotherapeutic Preparations (due to 238U, 232Th, 222Rn and 220Rn) Estimated for Adult Moroccan Patients

We use a nuclear technique based on the determination of the detection efficiencies of solid state nuclear track detectors CR-39 and LR-115 type II (SSNTDs) for alpha particles emitted from the series of uranium-238 and thorium-232 in a phytotherapeutic sample and the measurement of alpha track densities registered on these detectors to assess alpha activities due to uranium-238;thorium-232;radon and thoron in samples of phytotherapeutic preparations consumed by Moroccan adult patients. For modern preparations, the alpha activities due to 238U, 232Th and 222Rn range from 14.27 mBq/kg to 22.02 mBq/kg, from 6.27 mBq/kg to 9.64 mBq/kg and from 14.27 Bq/kg to 22.02 Bq/kg respectively. For classical preparations, the alpha activities due to 238U, 232Th and 222Rn range from 16.73 mBq/kg to 24 mBq/kg, from 7.34 mBq/kg to 10.82 mBq/kg and from 16.73 Bq/kg to 24.72 Bq/kg respectively. A dosimetric model for ingestion has been highlighted to determine committed equivalent dose to different compartments of human gastrointestinal system due to the ingestion of phytotherapeutic preparations by Moroccan adult patients. The maximum overall effective dose due to 238U, 232Th, and 222Rn after the ingestion of the studied phytotherapeutic preparations, was found equal to 38 × 10-8 S·vy-1 which is less than the dose limit given by the international commission for radiological protection in it publication 56.