222Rn Exhalation Rate Research Articles

Radiological characterization of materials used in the Italian heritage buildings

Building materials (BMs) can cause significant gamma dose indoors due to their natural radionuclide content. In 2013, the European Directive 59/2013/EURATOM introduced, in annex XIII, a list of types of BMs of interest for the content of gamma-emitting radionuclides among which materials or additives of natural igneous origin, such as granitoids, tuff and lava, are included. These materials have been largely employed for decorative and structural purposes in the course of centuries in the Italian heritage buildings. Aim of this study is to assess the contribute of BMs in terms of alpha exposure. Six samples of different materials, characterized in a previous study by the authors in terms of radiological content by means of a gamma spectrometry, have been analyzed in order to determine the specific exhalation rate of 222Rn, the radon emanation coefficient and excess in indoor radon concentration. Results confirm that BMs of natural igneous origin can play an important role in terms of alpha radiation dose and internal exposure due to the inhalation of the alpha particles emitted.

Measurements of radon exhalations and radiological doses using LR-115 (II) nuclear track detectors in Tiru region of the Naga Schuppen Belt, India.

In this present study, the nuclear track detector LR-115 (II) was employed to assess radon (222Rn) exhalation rate, effective radium (226Ra) content, and the annual effective dose from coal and soil samples collected in and around the coal mining area of Tiru region of Nagaland, India. The 222Rn mass and surface exhalation rates and 226Ra contents were found to be in the ranges of 7.3-17.3 mBq kg-1 h-1, 242.9-573.6 mBq m-2h-1 and 1.0-2.3Bqkg-1, respectively, for coal and 15.8-22.0 mBq kg-1 h-1, 523.8-730.4 mBq m-2h-1 and 2.1-2.9Bqkg-1, respectively, for soil. The 222Rn exhalation rates and 226Ra contents in soils were found to be higher than in coal. The estimated annual effective doses for coal and soils were found to be in the ranges of 17.6-41.6 and 38.0-53.0μSv y-1, respectively. This study is an important contribution to the understanding of radiation exposure in the coal mining area of the thrust-bound sedimentary sequence of the Naga Schuppen Belt, and it would have potential impact on further human health studies. However, the measured values for all the samples were found to be within the globally recognised permissible range.

A study of 222Rn/220Rn exhalation rate and indoor 222Rn/220Rn levels in higher Himalayan terrain.

The noble radioactive gas radon and its isotope thoron dominate terrestrial radiation in the indoor environment. These gases eventually disintegrate generating radioactive ions that readily adhere to aerosol particles. This study was conducted in a tectonically active location with significant radon concentrations. The obtained average values of radon mass exhalation and thoron surface exhalation rate from this study are higher than the global average values of 56 mBq kg-1h-1 and 1000 mBq m-2s-1, respectively. As the exhalation rates are higher, naturally the average radon and thoron concentrations are also greater than the worldwide average values of 40 and 10Bqm-3, respectively. No significant correlation was observed between 222Rn and 220Rn exhalation rate and indoor 222Rn/220Rn concentration. The exposure dose due to 222Rn, 220Rn and their progenies shows no significant health risk.

Measurements of 222Rn exhalation rates, effective 226Ra contents, and radiological risks from geological samples of Kopili Fault Zone and gneissic complex of Shillong Plateau, India

Abstract This report unveils the outcomes of measurements of 222Rn exhalation rates, effective 226Ra content, and the annual effective dose for rocks and soil collected in the vicinity and far from the seismically active Kopili Fault Zone, India. LR-115 (II) nuclear track detector has been used to investigate radiation exposure in the seismically active fault zone and gneissic complex of the Shillong Plateau, which have significant geological characteristics and frequently produce earthquakes. In this study, 222Rn mass exhalation rates for granite, gneiss, and soil samples collected near and far from the fault were calculated to be in the ranges of 73.2–83.0, 11.0–14.8, 21.1–70.7 and 34.3–65.5, 6.4–9.9, 19.1–28.9 mBq kg−1 h−1, respectively. Surface exhalation rates of 222Rn for granite, gneiss, and soil samples collected near and far from the fault varied between 2428.8–2751.7, 365.6–491.9, 698.3–2345.9, and 1138.6–2172.7, 211.9–328.2, 634.9–960.0 mBq m−2 h−1, respectively. The 226Ra contents of granite, gneiss, and soil collected in similar distributions were found to vary from 9.76–11.06, 1.47–1.98, 2.8–9.4, and 4.58–8.74, 0.85–1.32, 2.6–3.6 Bq kg−1, respectively. The annual effective doses attributed to 222Rn inhalation from exposure to the samples were calculated to be in the ranges of 176.3–199.8, 26.5–35.7, 50.7–170.3 and 82.7–157.7, 15.4–23.8, 46.1–69.7 μSv y−1, respectively, for granite, gneiss, and soil. The lifetime fatality-risks have also been analysed in this study. The samples that were collected in close proximity to the fault showed higher values than those that were collected farther away. However, the results reveal that the measured values are within the globally recognised permissible range.

Assessing Radon (222Rn) Exhalation Rates from Building Tiles in Duhok, Iraq

Assessing Radon (222Rn) Exhalation Rates from Building Tiles in Duhok, Iraq

Evaluation of Radon (222Rn) Exhalation Rates from Imported Granite Tiles Used as a Building Materials in Erbil Governorate, Kurdistan Region -Iraq

Evaluation of Radon (222Rn) Exhalation Rates from Imported Granite Tiles Used as a Building Materials in Erbil Governorate, Kurdistan Region -Iraq

Assessment of natural radioactivity and radon release potential of silurian black shales

Many countries are developing a radon action plan to provide decision-makers with a reliable tool for reducing the harmful effects of radon exposure in dwellings and among the general public and, accordingly, to implement land development strategies. Mapping the geogenic radon release in different geological environments could assist in delineating areas that require priority monitoring and regulation, as well as applying radon reduction techniques in newly constructed buildings. In this paper, the activity concentration of 238U, 226Ra, 232Th and 40K and the exhalation rate of 222Rn have been estimated for the Silurian black shales of Villasalto, a district in the south-eastern Sardinia (Italy). The radioactivity of 226Ra, 232Th and 40K radionuclides was found relatively high (256.32 ± 87.00 Bq.kg−1), low (44.16 ± 9.47 Bq.kg−1) and moderate to high (856.28 ± 392.41 Bq.kg−1) respectively. The radon emanation coefficient (E) and the radon production rate (PRn) have been calculated based on the analysis of the radon growth model inside a sealed chamber. E was found to correlate well with the activity concentration of 226Ra, as well as with the grain size of the soil/rock samples under investigation. PRn was relatively high, ranging from 212.54 to 524.27 Bq.m−3.h−1. Furthermore, the mean value of the main radiation hazard indexes (i.e., the radium equivalent activity, the outdoor gamma-ray dose rate and the annual effective dose) were found to be 299.07 ± 138.62 Bq.kg−1, 169.97 ± 75.58 nGy h−1 and 0.21 ± 0.09 mSv.y−1 respectively.

Investigation of 222Rn and 220Rn exhalation rates from soil samples of Pithoragarh District, India

Investigation of 222Rn and 220Rn exhalation rates from soil samples of Pithoragarh District, India

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.

An investigation of 222Rn exhalation rates from backfill mill tailings influenced by the different parameters in underground uranium mines

222Rn surface exhalation and mass exhalation rates measured from the backfill mill tailings using a new method comprising the smart-radon-monitor system and accumulation chamber in underground uranium mines are presented in this paper. The range values of 222Rn surface and mass exhalation rates were 0.6–4 Bq m−2 s−1 and 28–71 Bq kg−1 h−1, respectively. Further, Multivariate regression models involving radium content, porosity, moisture saturation and surface area to fit the 222Rn surface and mass exhalation of the backfill materials were developed in this paper. The curve fitting results showed that multivariate models could explain 86% of the variation of surface exhalation rate and 69% of the variation of mass exhalation rate from the backfill materials. This study also revealed that the 222Rn surface exhalation rate calculated based on the method of concentration gradient of 222Rn in soil, found to be about two times more than that of the measured surface exhalation rate. However, the theoretical 222Rn exhalation rate was prone to various uncertainties including a variation of moisture saturation, the occurrence of adsorption and advection in the backfill mill tailings. Therefore, the values of the 222Rn exhalation rate measured inside underground uranium mines are more realistic.

Measurement of Radium and Radon Exhalation Rate in Marble Samples used in Al-Bayda City Market-Libya

The aim of the present study is to measure the activity concentrations of 226Ra, 222Rn, the mass exhalation rate of 222Rn, and the annual effective dose of radon in marble samples collected from Al-Bayda city local market –Libya. Samples were measured by using a low-background NaI (Tl) detector. The average activity concentrations of 226Ra and 222Rn were 72.57 Bq.kg-1 and 597.85 Bq.m-3.The radon exhalation rate in marble samples vary from 0.05-0.30 Bq.kg-1.S-1 with an average of 0.13 Bq.kg-1.S-1. The annual effective dose of radon was calculated in samples under investigation. For most samples, the values were lower than the maximum permissible dose limits. It can be concluded that marble samples under investigation do not pose any radiological hazard to the dwellers of buildings used in their construction.

Measurement and analysis of 222RN in the commonly used building construction materials

Humans are constantly exposed to ionizing radiation, which is naturally occurring in the earth's crust. On the surface of the earth, the composition of radionuclides varies from place to place depending on the geological condition. Radon is a radioactive inert gas that emits radiation, contributing a large portion of the amount of radiation received by humans on earth. For radon studies, commonly used building material and soil samples are collected such as rocks, soil, sand and various types of cement etc from the local market, construction site and hardware stores. The concentration of 222Rn and mass exhalation rate was studied in the samples of building materials used in the province of Pune District, Maharashtra, India. In the present study active device AQTEK Smart RnDuo was used to measure the radon concentration and mass exhalation rate for the building construction material. In the current study, for soil samples shows radon concentration varies from 279±22Bq/m3 to 457±23Bq /m3 for with a mean value 342±22 Bq/m3, radon mass extraction rate varied from 9.64±0.54 mBq/Kg/hr to 18.84±1.5mBq/Kg/hr with mean value 13.5±1.04 mBq/Kg/hr.

Radiological assessment of urban soil samples in the residents of a central Anatolian volcanic province, Turkey

ABSTRACT The concentration of natural and anthropogenic radionuclides, emanation fraction (EF), and mass (χM) and area (χA) exhalation rate of 222Rn in urban soil samples collected from dwelling areas in Nevşehir city located in a region known as the central Anatolian volcanic province of Turkey were determined using gamma-ray spectroscopy. The average activity concentrations of 226Ra, 228Ra, 40K and 137Cs were measured as 60.2 ± 3.8, 50.1 ± 2.8, 631.0 ± 29.7 and 5.5 ± 0.4 Bq/kg, respectively. The average concentration of 222Rn in soil and air was estimated as 27 kBq/m3 and 84 Bq/m3, respectively. The average values of EF, χM and χA were found as 20%, 25.4 μBq/kg⋅s and 20.2 mBq/m2⋅s, respectively. The average values of outdoor absorbed gamma dose rate, external and internal annual effective dose and lifetime cancer risk estimated for radiological assessment were found as 85 nGy/h, 104 µSv/y, 797 µSv/y and 4.1 × 10−4, respectively.

Solidification of uranium mill tailings by MBS-MICP and environmental implications

Uranium mill tailing ponds (UMTPs) are risk source of debris flow and a critical source of environmental U and Rn pollution. The technology of microbial induced calcium carbonate precipitation (MICP) has been extensively studied on reinforcement of UMTs, while little attention has been paid to the effects of MICP on U & Rn release, especially when incorporation of metakaolin and bacillus subtilis (MBS). In this study, the reinforcement and U & Rn immobilization role of MBS -MICP solidification in different grouting cycle for uranium mill tailings (UMTs) was comprehensively investigated. The results showed that under the action of about 166.7 g/L metakaolin and ∼50% bacillus subtilis, the solidification cycle of MICP was shortened by 50%, the solidified bodies became brittle, and the axial stress increased by up to 7.9%, and U immobilization rates and Rn exhalation rates decrease by 12.6% and 0.8%, respectively. Therefore, the incorporation of MBS can enhance the triaxial compressive strength and improve the immobilization capacity of U and Rn of the UMTs bodies solidified during MICP, due to the reduction of pore volume and surface area, the formation of more crystals general gypsum and gismondine, as well as the enhancing of coprecipitation and encapsulation capacity.

RADON AND THORON EXHALATION RATES FROM EARTHEN BUILDING MATERIALS USED IN HIGH BACKGROUND RADIATION AREAS OF HOMA AND RURI, KENYA.

222Rn and 220Rn surface exhalation rates from earthen building materials used in high background radiation areas of Homa and Ruri, Kenya have been measured using an accumulation chamber coupled with RAD7 detector. Activity concentrations of 226Ra and 232Th in the building materials were determined by γ-ray spectroscopy. In Homa the average 222Rn surface exhalation was 1±0.1 mBqm-2s-1, while that of 220Rn was 18±2 Bqm-2s-1; in Ruri 222Rn was 0.9±0.1 mBqm-2s-1 and 220Rn was 25±3 Bqm-2s-1. 222Rn was 26 times lower than world average and 220Rn was higher by a factor of 21. Average 232Th in Ruri was 1094±55Bq/kg, three times that in Homa; 226Ra was 129±10 and 111±6Bq/kg in Homa and Ruri, respectively. There was a strong correlation between exhalation rate of 222Rn and concentration of 226Ra, as well as between 232Th and 220Rn. Thus, 220Rn was the major contributor to the inhaled dose in earthen dwellings of the two regions.

Evaluation of natural radioactivity levels and 222Rn, 220Rn exhalation rate in the soil of the Himalayan belt of Uttarakhand, India

Evaluation of natural radioactivity levels and 222Rn, 220Rn exhalation rate in the soil of the Himalayan belt of Uttarakhand, India

Quantification of 222Rn/ 220Rn exhalation rates from soil samples of Champawat region in Kumaun Himalaya, India

Quantification of 222Rn/ 220Rn exhalation rates from soil samples of Champawat region in Kumaun Himalaya, India

222Rn Exhalation Rates from Some Granite and Marble Used in Korea: Preliminary Study

The objective of this study was to establish a test method for assessing radon exhalation rates from building materials considering radon related environmental policy and research in Korea. This method was established in consideration of cost-effectiveness based on the International Standards Organization (ISO) method and the closed chamber method, which is an evaluation method for the emission of hazardous chemical substances from building materials in Korea. The assessment of radon exhalation rates from five types each of granite and marble used in the construction industry in Korea gave mean radon exhalation rates of 0.497 ± 0.467 Bq/m2∙h from granite and 0.193 ± 0.113 Bq/m2∙h from marble, indicating higher radon exhalation rates from granite. These results are consistent with those of a previous study, indicating that granites are more likely to show higher radon exhalation rates than marbles.

Measurement of radon exhalation rate from building materials: The case of Highland Region of Ecuador

Exposure to 222-Radon (Rn) usually occurs in closed environments as effect of the Rn exhaled from building materials, soil or water. While building materials provide a protection barrier to outdoor natural radiation (terrestrial and cosmic), their radionuclide composition could increase the indoor Rn exposure. In fact, the Rn exhalation of building materials is of great importance from the viewpoint of mitigation and public health in very specific conditions. This work presents the Rn exhalation rates of 40 building materials (concrete blocks, clay brick, granite and concrete samples) produced and used in Ecuador, as well as the effective dose for a reference dwelling. Rn concentration measurements were performed using the closed chamber method and a RAD7 equipment. The resulting Rn exhalation rates were found to be in the range from 0 to 7.83 Bq·m-2·h-1. The highest surface exhalation rate was detected in granite samples, while clay bricks show Rn exhalation below the minimum detection level (0.05Bq·m-2·h-1). In the reference dwelling, the effective dose rates caused by Rn exhalation from building material range from 0.019 up to 0.112 mSv/y. However, the effective dose rate depends on the exposure time and quantity of granite used. Our results could be of immediate help to choose suitable building materials to ensure a safe indoor environment for the dwellers.

Dose rates evaluation of some granitic rocks from the Paraná State

Granitic rocks, widely used as building materials, are known to contain natural radionuclides and can be an important source of radiation for the population. Thirty-four samples of granite rocks from geological occurrences in Paraná state were measured with an HPGe detector for evaluation of226Ra, 232Th and 40K activity concentrations. The effective annual external dose was evaluated from these radionuclides activities using a dosimetric room model with dimensions 4 m x 5 m x 2.8 m in which all wallsare internally coated with granites of thickness 2 cm and considering an annual exposure time of 7000 h. This value was suggested by the European Commission on Radiological Protection for superficial coating materials. The internal exposure was evaluated from radon air concentration of the model room, simulated from an exhalation rate of 222Rn, determined with CR-39 solid state nuclear track detectors using the sealed can technique, considering a ventilation rate of 0.5 h-1 and an annual exposure time of 7000 h. The results of this study showed that the increase in the annual effective dose ranged from 62 ± 3 μSv.a-1 to 138 ± 1 μSv.a-1 from external gamma rays and the increase in the annual effective dose ranged from 0.39 ± 0.04 μSv.a-1 to 70 ± 4 μSv.a-1 from radon inhalation. All results stayed below 1 mSv.a-1 recommended by the European Commission on Radiological Protection.