Exhalation Rate Research Articles

Study on radon (222Rn) emanation coefficient and mass exhalation rate from heavy minerals of high specific gravity

A study on 222Rn emanation coefficient and mass exhalation rate was carried out for different minerals having high specific gravity collected from a natural high background radiation area of India. The mass exhalation rate varied from 31 ± 0.5 to 2366 ± 36 mBq kg−1 h−1 and the radon emanation coefficient varied from 1.02 × 10−2 to 2.04 × 10−1. The radon escape probability was highest in garnet mineral indicating the uniform distribution of radium atoms on the mineral surface and smaller grain size than other minerals. Statistical analysis revealed that the radon mass exhalation rate was positively correlated with the 226Ra activity whereas no such strong significant correlation was observed between radon emanation coefficient and 226Ra activity.

Implications on dose estimation and dispersion patterns of thoron in a typical indoor environment.

A model that describes the pollutant sources/sinks and inlet-outlet can help to assess the indoor exposure. Short half-life of radioactive thoron (220Rn) makes it vital and an interesting element to study its dispersion behavior. This work presents an extensive depiction of the influence of indoor environment thoron dispersion under fixed boundary conditions within the volume domain of 90 m3 using computational fluid dynamics (CFD) software. For the desirable air flow, inlet and outlet are considered in the room and the k-ɛmodel is used. The thoron distribution is studied at different locations and different heights to cover the whole room. Obtained dispersion patterns vary at different locations and indicate non-uniformity of thoron level with elevated values in the room corners. Mean concentration was found to be 11Bq/m3 with the exhalation rate of 0.102 Bqm-2s-1. Some stagnant zones were found especially at the corners where the concentration is almost 5 times the average concentration. Such varying thoron level results in the overestimation and underestimation of the dose. The inhomogeneous behavior of thoron may cause variation in equilibrium factor. A simulated model is beneficial in understanding the radioactive gas behavior and has its importance in planning to find the correct dose estimation and, therefore, the best mitigation techniques.

A Study of Natural Radioactivity Levels and Radon/Thoron Release Potential of Bedrock and Soil in Southeastern Ireland.

Radon (222Rn) and thoron (220Rn) account for almost two-thirds of the annual average radiation dose received by the Irish population. A detailed study of natural radioactivity levels and radon and thoron exhalation rates was carried out in a legislatively designated “high radon” area, as based on existing indoor radon measurements. Indoor radon concentrations, airborne radiometric data and stream sediment geochemistry were collated, and a set of soil samples were taken from the study area. The exhalation rates of radon (E222Rn) and thoron (E220Rn) for collected samples were determined in the laboratory. The resultant data were classified based on geological and soil type parameters. Geological boundaries were found to be robust classifiers for radon exhalation rates and radon-related variables, whilst soil type classification better differentiates thoron exhalation rates and correlated variables. Linear models were developed to predict the radon and thoron exhalation rates of the study area. Distribution maps of radon and thoron exhalation rates (range: E222Rn [0.15–1.84] and E220Rn [475–3029] Bq m−2 h−1) and annual effective dose (with a mean value of 0.84 mSv y−1) are presented. For some parts of the study area, the calculated annual effective dose exceeds the recommended level of 1 mSv y−1, illustrating a significant radiation risk. Airborne radiometric data were found to be a powerful and fast tool for the prediction of geogenic radon and thoron risk. This robust method can be used for other areas where airborne radiometric data are available.

Investigating the Level of Radon 222Rn and Radium 226Ra in Soil Samples Taken From Al-Amarah in the South of Iraq

Radon (222Rn) is created in the soil by radioactive decay of Radium (226Ra) and then emitted from the ground into the atmosphere (exhalation), environmental assessments of radon gas (222Rn) are keys to the assessment of air pollution. The major objective of the current study was to examine the (222Rn) exhalation rates and the (226Ra) concentrations in the soil samples. Thirty soil samples have been collected from ten streets in the region. The (222Rn) exhalation rate and concentrations of (226Ra) in soil samples were calculated using “Can Technique”. The measurements have shown that the surface and mass exhalation rate were varied from 3.9∓0.3 to 18.3∓0.3 μBq.kg−1.s −1, with a mean value of 7.8∓0.3 μBq.kg−1.s−1, and 12.9∓0.5 to 60.7∓1 μBq.m−2.s−1, with a mean value of 25.5∓0.9 μBq.m−2.s−1, respectively. In addition, the results showed that the values for 226Ra concentrations ranged from 1.8∓0.04 to 8.7∓0.1 Bq.kg−1, with a mean value of 3.7∓0.1 Bq.kg−1. Overall, the indications showed that the levels of (226Ra) in soil samples are less than the hazardous levels of human health 370 Bq.kg−1.

Prediction of Indoor Radon Concentration through the Exhalation from Korean Yellow Residual Soil, Hwangtoh as a Building Material

The radon gas from nature mainly considers a cause of radon problems, and it is closely affect human life cycle. Korean yellow residual soil, Hwangtoh, widely used as a building material, is considered to be one of major sources of indoor radon. However, there have, as yet, been no studies about radon from Hwangtoh in mass market brands. Here, we investigated the indoor radon concentrations and exhalation rates in four Hwangtohs from different brand names and regional features. The Closed Chamber Method (CCM) conducted by a Continuous Radon Monitor (CRM) has been used for the rates of radon exhalation. Based on equations of previous references, the indoor radon concentrations were deducted. As a result, the radon surface exhalation rates resulted in the 1.4208 to 3.0293 Bq·m2·h-1 range. Significant differences were found among Hwangtohs according to production regions. Materials with higher radon concentration required a longer time to reach a quasi-steady state in a given environment, in other words, the number of half-life cycles increased from a set starting point. The experimentally identified Hwangtohs demonstrated its safety for construction purposes. There exists, so far, a possibility to exert influence radon emanation due to unidentified factors. Therefore, it is necessary to corroborate with more research by increasing the number of Hwangtohs, considering the other references reported high radon exhalation rates. In addition, it is highly recommended that the radon exhalation rates should be measured for all building materials for preventing human health before the material usage.

Annual Average Internal Dose Based on Alpha Emitters in Milk Sample

Natural radioactivity is common in the environment. As well as in geological formations such as soil, rock, air, water and plants. Which required extensive researches in many countries are due to the global interest in exposure to natural radioactivity. Ten different samples of milk collected from Iraqi markets were evaluated for concentration of alpha radioactivity (uranium concentration, effective radium content and radon concentrations) using CR-39. After exposure, the detectors were etched in a (NaOH) solution of normality (6.25 N) at a temperature of 70 °C for 8 hours. The tracks were calculated by the microscope track-counting system. At a rate of 0.171 ppm, uranium concentrations ranged between 0.079 – 0.263 ppm. While, the effective radium content varied from 53.724 - 178.47 mBq/kg with an arithmetic rate of 116.096 mBq/kg. The variation of the radon exhalation values for the mass unit and for the area unit was also observed between 0.406 - 1.349 mBq/kg.h and 3.076 -10.217 mBq/m 2.h, at a mean rate of 0.943 mBq/kg.h and 6.646 mBq/m2.h, respectively. The average of annual average internal effective dose (AAIED) due to ingestion of 222Rn in milk samples in children and adults has been found 0.60 nSv/y and 0.2 nSv/y respectively, there are excellent correlation between radium concentrations and radon exhalation rate and uranium concentration(R2=1). Thus, the results of this study do not constitute a health hazard to the lives of people because they are within the limits allowed internationally.

Quantification of the effect of temperature difference between concrete and indoor air, and water content in concrete on radon exhalation

Effects of temperature difference between indoor air and concrete, and water content in concrete, on Rn-222 exhalation were investigated. In concrete with 0% water content, the heat generated due to temperature difference between concrete and indoor air could raise Rn-222 exhalation rate by 2.6 times. The Rn-222 exhalation rate rose initially, then declined as water content in concrete was increased. The maximum Rn-222 exhalation rate was 4.4 mBq m−1 s−1 in concrete with 10% water content. A grey prediction model was established for predicting Rn-222 exhalation rates and exposure doses of residents due to different indoor temperature differences with concrete.

The possibility of the phosphogypsum use in the production of brick: Radiological and structural characterization

In this paper, phosphogypsum (PG) with the content of 226Ra of about 500 Bq kg-1 was used as a clay additive in mass ratios of (0−40) % and its influence on the radiological and mineralogical characteristics of the obtained brick samples was monitored. After sintering the samples at 1000 ℃, the formation of the mineral phase gehlenite was observed, and its share increased with the share of PG in the samples. The Monte Carlo method was used to determine the gamma dose rates, and consequently annual effective dose, for a standard room, with dimensions 4 × 5 × 2.8 m, whose walls were built of brick with PG. The obtained values were in the range (0.22–0.35) mSv y-1. In addition, the active device RAD7 was used to determine the radon surface exhalation rates from the samples, which were found to be in the range (63−150) mBq m-2 h-1. The estimated indoor radon concentrations were found to be drastically lower than 100 Bq m-3, leading to low radon inhalation doses. However, estimated annual effective doses from external gamma exposure were found not to be insignificant.

CFD based simulation of indoor radon distribution from the use of different brands of decorative glazed tiles made in China

ABSTRACT The radon exhalation rates of the surface of 10 different brands of glazed tiles made in China are measured and assessed. The experimental results reveal that the values of radon exhalation rate from the surface of glazed tiles are in the range of 0.36–2.52 Bq·m2 h−1, with a mean of 1.48 Bq·m2 h−1. These measurements obtained in this study are much lower than the typical radon exhalation rate international reference value of soil, and are also within the range of the reported literatures. Meanwhile, these data are taken as input parameters of computational fluid dynamics (CFD) model for simulation comparative study. The different plane distribution of radon from the use of different brands of glazed tiles in the model residential room is simulated. The simulation results show that the distribution of radon concentration in different XY plane is un-even, and the values of radon concentrations in XY plane is decreasing with the increase of z height. Deducting the contribution of the worldwide typical outdoor radon concentration, the maximum mean radon concentration at z = 0.5 m height was found to be 6.03 Bq·m−3 in Brand ‘B.H’ which accounts for 13.40% of the worldwide geometric mean indoor radon concentration. Combined with the measurement and simulation results, it can be known that the use of glazed tiles is not the main source of indoor radon, but glazed tile with lower radon exhalation rate is still needed for health purpose.

Long-Term Measurements of Radon and Thoron Exhalation Rates from the Ground Using the Vertical Distributions of Their Activity Concentrations.

A long-term measurement technique of radon exhalation rate was previously developed using a passive type radon and thoron discriminative monitor and a ventilated type accumulation chamber. In the present study, this technique was applied to evaluate the thoron exhalation rate as well, and long-term measurements of radon and thoron exhalation rates were conducted for four years in Gifu Prefecture. The ventilated type accumulation chamber (0.8 × 0.8 × 1.0 m3) with an open bottom was embedded 15 cm into the ground. The vertical distributions of radon and thoron activity concentrations from the ground were obtained using passive type radon-thoron discriminative monitors (RADUETs). The RADUETs were placed at 1, 3, 10, 30, and 80 cm above the ground inside the accumulation chamber. The measurements were conducted from autumn 2014 to autumn 2018. These long-term results were found to be in good agreement with the values obtained by another methodology. The radon exhalation rates from the ground showed a clearly seasonal variation. Similar to findings of previous studies, radon exhalation rates from summer to autumn were relatively higher than those from winter to spring. In contrast, thoron exhalation rates were not found to show seasonal variation.

Study of primordial radionuclides and radon/thoron exhalation rates in Bageshwar region of Kumaun Himalaya, India

The measurements of primordial radionuclides (226Ra, 232Th and 40K) and radon exhalation rates in soil samples were performed in Bageshwar region of Kumaun Himalaya, India using gamma-ray spectrometry and scintillation detector based radon monitor, respectively. The average concentrations of 226Ra, 232Th and 40K in the investigated region were found to be 36 Bq kg−1, 50 Bq kg−1 and 1595 Bq kg−1, respectively. The average values of radon and thoron mass exhalation rates were observed to be 29 mBq−1 kg−1 s−1 and 256 mBq−1 kg−1 s−1, respectively. The average value of thoron surface exhalation rates was observed to be 2281 mBq−1 m−2 s−1. The external exposure to 226Ra, 232Th and 40K is estimated in terms of different hazard assessment indices and dose quantities. The high values of 232Th content in soil samples indicate the presence of thorium mineralization in the vicinity of study area. The methodology adopted and results obtained are discussed in details.

The first radon potential map of the Campania region (southern Italy)

This is the first paper to report a potential map of radon (222Rn) distribution in the Campania region of southern Italy, using the geostatistical kriging interpolation method using QGIS® software. The response variable is the 222Rn indoor measurements, whereas proxy variables used as predictors are: geology, faults, soils permeability, meteorological/climatic parameters, 238U distribution, 222Rn emanation coefficients and exhalation rates, 226Ra in building materials and gamma dose rate in dwellings. The map shows high radon potential areas in correspondence to the main volcanic centres and the faults network of the region. The map is a useful instrument to identify radon-prone areas and evaluate radon risk level for the population.

Experimental study of pore characteristics and radon exhalation of uranium tailing solidified bodies in acidic environments.

The pore characteristics and radon exhalation of uranium tailings solidified in an acid environment were investigated in this study. Tailings from the beach of a uranium tailing reservoir in the acid rain area of Central China were selected as samples and solidified with cement, slag powder (GGBS), metakaolin (MK), or slag powder and metakaolin (GM), then immersed in simulated acid rain solution for 60 days. The transverse relaxation time T2 distribution and porosity of each solidified sample before and after immersion were measured by nuclear magnetic resonance (NMR) and the cumulative radon concentration before and after immersion was measured by a RAD7 radon meter. The experimental results show that the nuclear magnetic resonance T2 distribution curve shifts to the left, the peak amplitude decreases, and the pores in the sample gradually shrink as the admixture content increases. The porosity and radon exhalation rate of solidified samples also appear to decrease gradually as admixture content increases; a quadratic function relationship was observed between porosity and radon exhalation rate. The pore size and effective pore volume of solidified samples increase as immersion time increases, while the radon exhalation rate increases and the pore volume gradually increases. The results of this study may provide a sound theoretical basis for the solidification treatment of uranium tailings in engineering practice.

Determine the Contaminations of Radon in the Drinking Water Using NTDs (CR-39) and RAD7 Detectors

This presented study was performed to determine the contaminations of radon in twenty-five drinking tap water samples in Penang/Malaysia. The concentration of 222Rn, specific activity of 226Ra, radon emanation factor, equilibrium radon concentration, annual effective dose and mass exhalation rate were measured in drinking water samples available under study by using two methods, passive method (NTDs (CR-39) and active method (RAD7 monitoring). Also, the pH and electrical conductivity of the samples were measured. The results showed that the maximum concentration of radon was found in sample 7 to be 98.154 Bq m−3 and the minimum concentration of radon was found in sample 4 to be 39.715 Bq m−3 with an average of 66.521 Bq m−3. The maximum concentration of radium was found in sample 7 to be 1266.036 × 10−3 Bq kg−1, and the minimum concentration of radium was found in sample 4 to be 530.729 × 10−3 Bq kg−1 with an average (899.999 × 10−3 Bq kg−1). The results obtained from the passive technique (CR-39) and active technique (RAD7) were in good agreement together (66.521, 63.533) Bq m−3, because the passive method and active method are simple and reliable analytical methods. An average annual effective dose (0.770 mSvy−1) was found to be below the value (3–10 mSvy−1) that was reported by the ICRP (1993), therefore, there is no evidence of health problems. Significant strong positive correlations found (r = 1, Pearson Correlation, p < 0.000) in concentrations of radon, radium and annual effective dose. All the results obtained were within the international levels as given by UNSCEAR (United Nations Scientific Committee on the Effect of Atomic Radiation).

Determination of Radium and Radon Exhalation Rate as a Function of Soil Depth of Duhok Province - Iraq

ABSTRACT Radon is a naturally occurring radioactive gas; generated during the decay process of radium, when alpha particles start to be emitted, turning the radium into radon. The rate of radon gas that escapes from the soil into the atmosphere is called radon exhalation rate. In this study, radon, radium, and both radon surface and mass exhalation rates were measured for 40 samples of soil at four sampling depths (10, 20, 30, and 40 cm) in three districts of Duhok province. For the radon measurement, alpha-sensitive RAD7 detector was used. While radium concentration measured by well type NaI (Tl) detector. Analysis, shows radon surface exhalation rate vary from 24 ± 10.7 to 57 ± 2.5 Bq.m−2h−1 with an average value of 38.7 ± 8.9 Bq.m−2h−1. While mass exhalation rate vary from 1.2 ± 0.9 to 6.7 ± 1.6 Bq.kg−1.h−1 with an average of 4.2 Bq.kg−1.h−1. Furthermore, the results showed that radon exhalation rate and radon concentrations in soil have direct proportion to soil depths. Overall, radon concentration, radium content and both surface and mass exhalation rate in all sample points present a good correlation and less than global mean average recommendation [30].

RADON FOOTPRINT FROM THE PHOSPHOGYPSUM WASTE STACK NEAR ZGRPOLCI LOCALITY, VELES, REPUBLIC NORTH MACEDONIA

Five locations and five samples of materials from the phosphogypsum waste stack near Zgrpolci locality, in the vicinity of the city of Veles, were checked for their radon concentrations in air and phosphogypsum radon exhalation rate. The accumulation method using AlphaGUARD DF2000 device was used for specific exhalation rate determinations as well as for radon concentrations in air. The activity concentrations of 222Rn at 5 different sampling locations of the anthropogenically introduced phosphogypsym waste stack near the Zgrpolci locality ranged from 21.02 up to 142.20 Bq kg-3. The 222Rn exhalation rates from these materials (from the same 5 locations) were in the range of 592.27-897.99 mBq m-2 h-1 .

Evaluation of Alpha Particles Concentration and Exhalation Rate in Soil Samples in Kifle City/Iraq

Radon concentration was measured by sealing-can technique based on the CR-39 detectors at different locations in Kifl. The disclosure to radon progeny (EP) have been studied. The results show that the radon concentration 2o5 to Bq/m3. The exhalation rates and the radiation exposure from samples of soil collected from different sites at Kifl city. The total average values of radon concentrations in topsoil (ocm depth) were 26oBqm-3. The dissolved in soft tissues (Ds) and the dose rate due to alpha in lung (Dl) were calculated. The results concentration of radon in this work good agreement with radon concentration levels recommended by the (ICRP) International Commission on Radiological Protection

Estimation of radiological impact on residents due to household storage of coal used for heating in Serbia

This paper aims to estimate a potential radiological risk from different kinds of coals used for domestic heating in Serbia, by measuring the activity concentration of radionuclides and radon exhalation rate. The obtained radon mass exhalation rate ranges from (5.3 ? 3.1) mBqkg?1s?1 to (70.3 ? 9.4) mBqkg ?1s?1 and was highest for lignite type of coal. It is estimated that coal stored in the basement could contribute up to 50 Bqm?3 of indoor radon concentration at the ground level. Activity concentrations of 226Ra, 232Th, 40K, 238U, 235U, and 210Pb in analysed coal samples agree with previously reported concentrations of coal used in Serbia. The values of radium equivalent concentration and external hazard index indicate that the used coal does not represent a significant radiation hazard.

Measurement and spatial distribution pattern of natural radioactivity in a uranium tailings pond in Northwest China

ABSTRACT Numbers of radioactive tailings were produced in the process of uranium mining and milling.In this study,radiation environment monitoring was carried out on a decommissioned uranium mining and milling tailings pond in northwest China, and the governance effect and operation status of the tailings pond was investigated. The soil radionuclide activity concentration and ambient dose equivalent rate (H*(10)) were measured, and soil surface radon exhalation rate was calculated. The results shown that in the tailings pond and its surrounding area, the average soil radionuclide activity concentration was respectively 238U: 42.64±11.17 Bq·kg-1, 226Ra: 45.47±13.56 Bq·kg-1, 232Th: 33.30±7.33 Bq·kg-1, 40K: 631.33±72.05 Bq·kg-1, the average H*(10) was 63.32±6.46 nSv·h-1, and the average radon exhalation rate was 40.46±11.29 mBq·m-2·s-1.Radionuclide activity concentration, H*(10) and radon exhalation rate were within the range of world natural background. Spatial distribution of radioactivity was analyzed by OK interpolation based on the investigated data. According to the measured results and spatial interpolation analysis,the decommissioning governance effect of the uranium tailings reservoir is good, the operation is normal, and there is no migration or diffusion situation of radionuclides in the pond has been found.

Характеристика одышки у больных прогрессирующим фибротическим фенотипом интерстициальных заболеваний легких, ассоциированных с ишемической болезнью сердца

Study Objective: To compare the quantitative aspects of shortness of breath in patients with fibrous interstitial lung disease (ILD) associated with cardio ischemia; to compare analysis results of the data obtained during functional and instrumental examinations. Study Design: Open comparative study in parallel groups. Materials and Methods. The study included 47 patients with fibrous ILD: 8 patients had idiopathic pulmonary fibrosis; 25 patients had chronic hypersensitive pneumonitis, and 14 patients had fibrous non-specific interstitial pneumonia. The patients were divided into two groups: study group of 24 patients with fibrous ILD associated with cardio ischemia, and 23 controls with fibrous ILD without cardio ischemia. We analysed clinical symptoms, instrumental examination results, changes in patients’ functional status with and without cardiac pathology. Study Results. In patients with fibrous ILD and cardio ischemia, respiratory symptoms were more intensive than in patients without cardio ischemia. Patients with fibrous ILD and cardio ischemia experienced worsening of their shortness of breath statistically earlier (in 3.15 days) vs patients with isolated fibrous ILD, who had shortness of breath in 7.29 days (p &lt; 0.05). Patients with fibrous ILD and cardio ischemia demonstrated mixed functional changes: restrictive (reduced lung capacity and FVRC) and obstructive disorders (reduced FEV1 and instantaneous exhalation rate, МСВ25); statistically significant reduction in diffusing lung capacity, p &lt; 0.05. A shorter 6-minute walking distance, more marked desaturation (SрO2 reduction by 8.31% in the study group and by 2.12% in controls, p &lt; 0.05), higher scores of Borg Dyspnoea Scale and CRP scale (Clinical, Radiographic, and Physiologic scoring system) demonstrated statistically reduced tolerance to physical exercises in patients with cardio ischemia. CT scans did not reveal any differences in the intensity of interstitial changes in patients of both groups; “ground glass” areas were significantly more intense in patients with cardio ischemia, p &lt; 0.05. Pulmonary hypertension and structural changes in right compartments of heart were recorded in patients in both groups; however, left ventricular hypertrophy and dysfunction were noted only in patients with cardio ischemia. Conclusion. In patients with fibrous ILD associated with cardio ischemia, intensification of shortness of breath can be a sign of a progressive respiratory disease or a new event: coronary event, atrial fibrillation attack, cardiac failure, chronic cor pulmonale. Assessment of the functional status using Borg Dyspnoea Scale, CRP, Medical Research Council Scale is a tool to identify the reasons of dyspnoea in primary care settings, to develop an algorithm for instrumental differential diagnosis of shortness of breath. Keywords: progressive fibrous interstitial lung diseases, quantification of shortness of breath, cardio ischemia.