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1.
J Environ Radioact ; 229-230: 106542, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33581483

RESUMO

We present a novel application of machine learning techniques to optimize the design of a radiation detection system. A decision tree-based algorithm is described which greedily optimizes partitioning of energy depositions based on a minimum detectable concentration metric - appropriate for radiation measurement. We apply this method to the task of optimizing sensitivity to radioxenon decays in the presence of a high rate of radon-progeny backgrounds (i.e., assuming no physical radon removal by traditional gas separation techniques). Assuming other backgrounds are negligible, and considering sensitivity to each xenon isotope separately (neglecting interference between isotopes), we find that, in general, high resolution readout and high spatial segmentation yield little additional capability to discriminate against radon backgrounds compared to simpler detector designs.


Assuntos
Poluentes Radioativos do Ar , Monitoramento de Radiação , Radônio , Poluentes Radioativos do Ar/análise , Árvores de Decisões , Radônio/análise , Radioisótopos de Xenônio/análise
2.
J Environ Radioact ; 229-230: 106506, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33472114

RESUMO

In this study, a portable cascade impactor was developed to more efficiently determine the activity size distribution of attached radon and thoron progeny in a natural environment. The developed impactor consisted of four stages with a backup filter stage for collection of the aerosol samples. The aerosol cut points were set for 10, 2.5, 1, and 0.5 µm at a sampling rate of 4 L min-1. Five CR-39 chips were used as alpha detectors for each stage. To separate the alpha particles emitted from radon and thoron progeny, the CR-39 detectors were covered with aluminium-vaporized Mylar films. The thickness of each film was adjusted to allow alpha particles emitted from radon and thoron progeny to reach the surface of the CR-39 detectors. The particle cut-off characteristics of each stage were determined by mono-dispersive aerosols with particle sizes ranging from 0.1 to 1.23 µm from the collection efficiency curve. The test results showed that the respective cut-off size of stages 3 and 4 were close to the designed cut-points. Validation of the technique by comparison with two commercial devices confirmed that the developed technique could provide the necessary information to estimate the activity size distribution of attached radon and thoron progeny for dose assessment, especially, in a field survey where direct electric power is not available.


Assuntos
Poluentes Radioativos do Ar , Poluição do Ar em Ambientes Fechados , Monitoramento de Radiação , Radônio , Aerossóis , Poluentes Radioativos do Ar/análise , Poluição do Ar em Ambientes Fechados/análise , Habitação , Radônio/análise , Produtos de Decaimento de Radônio/análise
3.
J Environ Radioact ; 229-230: 106541, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33493872

RESUMO

A novel approach is proposed to detect underground nuclear explosions (UNEs) through the displacement of natural radon isotopes (222Rn and 220Rn). Following an explosion, it is hypothesized that the disturbance and pressurization of the sub-surface would facilitate the movement of radon from the depth of the UNE towards the surface resulting in increased soil gas activity. The resulting signal may be magnified by a factor of 2.0-4.9 by the decay of radon to its short-lived progeny. Increases in background activity may be useful for identifying locations to perform additional measurements, or as a detectable signal at monitoring stations. To validate this hypothesis, radon detection instrumentation was deployed at the Dry Alluvium Geology (DAG) site of the Source Physics Experiment (SPE) at the Nevada National Security Site (NNSS). Natural fluctuations in the soil gas activity due to barometric pumping, and the lower yield of the chemical explosions (1-50 t) made it difficult to confirm a displacement of radon from the explosions, and further study to validate the proposed hypothesis is recommended.


Assuntos
Monitoramento de Radiação , Radônio , Explosões , Geologia , Nevada , Radônio/análise
4.
Arch Environ Contam Toxicol ; 80(1): 308-318, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33398396

RESUMO

The presence of radioactive elements in groundwater results in high health risks on surrounding populations. Hence, a study was conducted in central Tamil Nadu, South India, to measure the radon levels in groundwater and determine the associated health risk. The study was conducted along the lithological contact of hard rock and sedimentary formation. The concentrations of uranium (U) varied from 0.28 to 84.65 µg/L, and the radioactivity of radon (Rn) varied from 258 to 7072 Bq/m3 in the collected groundwater samples. The spatial distribution of Rn in the study area showed that higher values were identified along the central and northern regions of the study area. The data also indicate that granitic and gneissic rocks are the major contributors to Rn in groundwater through U-enriched lithological zones. The radon levels in all samples were below the maximum concentration level, prescribed by Environmental Protection Agency. The effective dose levels for ingestion and inhalation were calculated according to parameters introduced by UNSCEAR and were found to be lesser (0.235-6.453 µSvy-1) than the recommended limit. Hence, the regional groundwater in the study area does not pose any health risks to consumers. The spatial distribution of Rn's effective dose level indicates the higher values were mainly in the central and northern portion of the study area consist of gneissic, quarzitic, and granitic rocks. The present study showed that Rn concentrations in groundwater depend on the lithology, structural attributes, the existence of uranium minerals in rocks, and the redox conditions. The results of this study provide information on the spatial distribution of Rn in the groundwater and its potential health risk in central Tamil Nadu, India. It is anticipated that these data will help policymakers to develop plans for management of drinking water resources in the region.


Assuntos
Água Subterrânea/química , Monitoramento de Radiação/métodos , Radônio/análise , Poluentes Radioativos da Água/análise , Sedimentos Geológicos/química , Índia , Urânio/análise
5.
Sci Total Environ ; 762: 144150, 2021 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-33418274

RESUMO

Uncertainty on long-term average radon concentration has a large impact on lung cancer risk assessment in epidemiological studies. The uncertainty can be estimated by year-to-year radon concentration variability, however few data are available. In Italy a study has been planned and conducted to evaluate year-to-year radon variability over several years in normally inhabited dwellings, mainly located in Rome. This is the longest study of this kind in Europe; repeat radon measurements are carried out for 10 years using LR-115 radon detectors in the same home in consecutive years. The study includes 84 dwellings with long-term average radon concentration ranging from 28 to 636 Bq/m3. The result shows that year-to-year variability of repeated measurements made in the same home in different years is low, with an overall coefficient of variation of 17%. This is smaller than most of those observed in studies from other European countries and USA, ranging from 15% to 62%. Influencing factors that may explain the differences between this study and other studies have been discussed. Due to the low yearly variability estimated in the present 10-year study, a negligible impact on lung cancer risk estimate for the Italian epidemiological study is expected.


Assuntos
Poluentes Radioativos do Ar , Poluição do Ar em Ambientes Fechados , Neoplasias Pulmonares , Radônio , Poluentes Radioativos do Ar/análise , Poluição do Ar em Ambientes Fechados/análise , Europa (Continente)/epidemiologia , Seguimentos , Habitação , Humanos , Itália/epidemiologia , Neoplasias Pulmonares/epidemiologia , Radônio/análise , Roma
6.
Environ Pollut ; 271: 116356, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-33387778

RESUMO

Residential radon exposure is a major public health issue in Switzerland due to the known association between inhaled radon progeny and lung cancer. To confirm recent findings of an association with skin cancer mortality, an updated national radon model is needed. The aim of this study was to derive the best possible residential radon prediction model for subsequent epidemiological analyses. Two different radon prediction models were developed (linear regression model vs. random forest) using ca. 80,000 measurements in the Swiss Radon Database (1994-2017). A range of geographic predictors and building specific predictors were considered in the 3-D models (x,y, floor of dwelling). A five-fold modelling strategy was used to evaluate the robustness of each approach, with models developed (80% measurement locations) and validated (20%) using standard diagnostics. Random forest consistently outperformed the linear regression model, with higher Spearman's rank correlation (51% vs. 36%), validation coefficient of determination (R2 31% vs. 15%), lower root mean square error (RMSE) and lower fractional bias. Applied to the population of 5.4 million adults in 2000, the random forest resulted in an arithmetic mean (standard deviation) of 75.5 (31.7) Bq/m3, and indicated a respective 16.1% and 0.1% adults with predicted radon concentrations exceeding the World Health Organization (100 Bq/m3) and Swiss (300 Bq/m3) reference values.


Assuntos
Poluentes Radioativos do Ar , Poluição do Ar em Ambientes Fechados , Neoplasias Pulmonares , Radônio , Poluentes Radioativos do Ar/análise , Poluição do Ar em Ambientes Fechados/análise , Exposição Ambiental/análise , Habitação , Humanos , Radônio/análise , Suíça
7.
Environ Monit Assess ; 193(2): 87, 2021 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-33501571

RESUMO

The Al Aziziah area is built on volcanic and granitic rocks. The igneous rocks always contain a high amount of naturally radioactive elements such as uranium, thorium and potassium, which produce gamma rays causing environmental hazards when exceeding the permissible limit. Radon gas is a result from the decomposition of uranium/thorium leaks into enclosed areas (e.g. homes or offices). This leakage is controlled by many conditions, and one of them is the underlining rock type. To work on such an environmental study, a gamma ray spectrometer survey was used. The uranium, thorium and potassium contents, as well as their ratios and the total radiation, were determined and mapped. The radiation dose rate was calculated and mapped in mSv/y and nGy/h units. The radiation contamination of groundwater is detected from the contour map of the dose rate over the artificial drainage lines of rains and floods which move this water to the groundwater wells. The main results are as follows: granitic rocks show an average dose rate of about 2.4 mSv/y, while the deposits of these rocks have an average dose rate of 1.2 mSv/y. A low average dose is recorded over the basalt. The average radiation dose recorded in the study area is 1.08 mSv/y, while its range is from 0.001 to 4.41 mSv/y. The estimated effective doses within the Al Aziziah area and vicinity area were higher than 1 mSv/y, which is the public exposure limit, and lower than the occupational exposure limit of 20 mSv/y. We recommend ventilating homes and offices in these places on an ongoing basis and constant radon measuring in closed places.


Assuntos
Monitoramento de Radiação , Radônio , Urânio , Doses de Radiação , Radônio/análise , Arábia Saudita , Tório/análise , Urânio/análise
8.
J Environ Radioact ; 227: 106501, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33310392

RESUMO

The influence of different building types on the activity concentration of Radon indoor is studied through transport models in soil and building materials. The numerical solutions of the relevant transport equations are solved by the finite differences method (FDM) and used to evaluate the indoor Radon activity concentration. Several boundary conditions are introduced to simulate the Radon entry into the buildings from soils and to assess the Radon activity concentration at the different floors. The types of dwelling investigated differ in the position of the lower floor respect to the ground. Comparisons are made to modeling assessments obtained considering different soil characteristics underneath the building and building materials to simulate indoor Radon activity concentration. These investigations lead to the conclusion that, in addition to the nature of the soil and building materials, the position of lower floor of dwellings plays a significant role in determining the amount of radon entry into residential buildings. This work is effective to assess the health hazards coming from the Radon accumulation in living environments.


Assuntos
Poluentes Radioativos do Ar , Poluição do Ar em Ambientes Fechados , Monitoramento de Radiação , Radônio , Poluentes Radioativos do Ar/análise , Poluição do Ar em Ambientes Fechados/análise , Habitação , Radônio/análise
9.
J Environ Radioact ; 227: 106500, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33310605

RESUMO

Dependence of indoor radon concentrations (IRCs) in the ground floors of 1200 buildings across Montenegro on 11 factors was analyzed. A group of 734 buildings, for which none of the analyzed factors was missing, was further analyzed using the logistic regression method, in order to develop a prediction model for IRC occurrence above the national reference level for new buildings (200 Bq/m3). Applying the forward stepwise method, and based on likelihood ratios, five explanatory variables-municipality, type of building, presence of basement, window frames, and period of construction-were selected for including into the final logistic regression model for predicting probability of IRC > 200 Bq/m3. The final model explained 77.1% of the observed IRCs, while the obtained Area under the Curve of 0.8018 classified the model as having a very high predictive ability. Achieving similar values for both the final prediction model and the validation model, for sensitivity, specificity, and accuracy, confirmed the applicability of the developed model.


Assuntos
Poluentes Radioativos do Ar , Poluição do Ar em Ambientes Fechados , Monitoramento de Radiação , Radônio , Poluentes Radioativos do Ar/análise , Poluição do Ar em Ambientes Fechados/análise , Habitação , Montenegro , Radônio/análise
10.
J Environ Radioact ; 228: 106512, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33341751

RESUMO

Extensive research has been conducted investigating the effects of ionizing radiation on biological systems, including specific focus at low doses. However, at the surface of the planet, there is the ubiquitous presence of ionizing natural background radiation (NBR) from sources both terrestrial and cosmic. We are currently conducting radiobiological experiments examining the impacts of sub-NBR exposure within SNOLAB. SNOLAB is a deep underground research laboratory in Sudbury, Ontario, Canada located 2 km beneath the surface of the planet. At this depth, significant shielding of NBR components is provided by the rock overburden. Here, we describe a Specialized Tissue Culture Incubator (STCI) that was engineered to significantly reduce background ionizing radiation levels. The STCI was installed 2 km deep underground within SNOLAB. It was designed to allow precise control of experimental variables such as temperature, atmospheric gas composition and humidity. More importantly, the STCI was designed to reduce radiological contaminants present within the underground laboratory. Quantitative measurements validated the STCI is capable of maintaining an appropriate experimental environment for sub-NBR experiments. This included reduction of sub-surface radiological contaminants, most notably radon gas. The STCI presents a truly novel piece of infrastructure enabling future research into the effects of sub-NBR exposure in a highly unique laboratory setting.


Assuntos
Radiação de Fundo , Monitoramento de Radiação , Radiobiologia , Incubadoras , Ontário , Radônio/análise
11.
J Environ Radioact ; 228: 106510, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33341753

RESUMO

Thoron (220Rn) exhalation from building materials has become increasingly recognized as a potential source for radiation exposure in dwellings. However, contrary to radon (222Rn), limited information on thoron exposure is available. As a result no harmonized test procedures for determining thoron exhalation from building materials are available at present. This study is a first interlaboratory comparison of different test methods to determine the thoron exhalation and a pre-step to a harmonized standard. The purpose of this study is to compare the experimental findings from a set of three building materials that are tested, and to identify future challenges in the development of a harmonized standard.


Assuntos
Poluentes Radioativos do Ar , Materiais de Construção , Monitoramento de Radiação , Radônio , Poluentes Radioativos do Ar/análise , Poluição do Ar em Ambientes Fechados/análise , Expiração , Habitação , Radônio/análise
12.
J Environ Radioact ; 226: 106368, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33077303

RESUMO

Radon mass balances in lakes can be used to trace transport processes along the sediment-water interface, such as groundwater discharge or pore water exchange. Understanding these transport processes is important, as they can affect the lake water budget, or biogeochemical cycles in lakes due to nutrient inputs. We present here a seasonal 222Rn mass balance of Lake Burullus (Northern Egypt), the second largest lake of Egypt. The Lake receives 222Rn from drainage water and the decay of 226Ra, and loses 222Rn via decay of 222Rn, atmospheric evasion and water discharge into the Mediterranean Sea. However, the mass balance reveals a significant surplus of 222Rn, which cannot be explained by the previously mentioned processes. The 222Rn surplus is especially high during the dry season, and might be explained by groundwater discharge and pore water exchange which transports 222Rn into the lake. Higher 222Rn fluxes into the lake during dry season might be explained by higher bioirrigation rates due to warmer temperatures, or higher groundwater discharge rates due to a higher hydraulic head on land caused by excessive irrigation in adjacent fields. Groundwater discharge and pore water exchange should be investigated in further detail in order to understand if they have effects on water budgets and biogeochemical cycles of Lake Burullus.


Assuntos
Monitoramento de Radiação , Radônio/análise , Poluentes Radioativos da Água/análise , Egito , Monitoramento Ambiental , Água Subterrânea , Lagos/química , Mar Mediterrâneo , Estações do Ano , Água
13.
J Environ Radioact ; 226: 106458, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33202288

RESUMO

Over 40 soil gas samples were collected both in post-industrial areas as well as in undisturbed areas in the region of Kvarntorp, Sweden. Radioxenon (133Xe) was detected in 15 samples and radioargon was detected in 7 from 10 samples analysed. The concentration of radioxenon and radioargon in soil gas ranged up to 109 mBq/m3 and 19 mBq/m3, respectively. During sample collection other soil gases such as radon, CO2 and O2 were also measured and soil samples were taken along with dose rate measurements. The field experiment presented here shows that it is possible to detect naturally occurring radioxenon and radioargon in soil gas simultaneously.


Assuntos
Poluentes Radioativos do Ar/análise , Monitoramento de Radiação , Radônio/análise , Poluentes Radioativos do Solo/análise , Radioisótopos de Xenônio/análise , Gases/análise , Solo , Suécia
14.
Chemosphere ; 263: 128096, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33297092

RESUMO

Studies on occurrence of radon in the environment are receiving growing attention worldwide due to its adverse impact on human health. Despite that, the dissolved radon in water is found to be a useful tracer in many hydrogeological studies. Although, several studies focused on the occurrence of high 222Rn in groundwater, the processes responsible for its variation is still not well understood. Hence, an attempt has been made in the present study to elucidate the underlying factors influencing the abundance 222Rn in hard rock (gneissic) aquifers of Karamana River Basin, southwest India. 222Rn in groundwater was analyzed in 71 dug wells during the pre-monsoon period of 2017. A large variability in 222Rn activities (170-68,350 Bq/m3) was noticed in groundwater and high activities were mainly seen in the khondalite formation. No significant dependencies between 222Rn activity and depth to water table, groundwater temperature and electrical conductivity were observed. However, majority of the presence of high 222Rn activity in groundwater matches with the location of lineaments. Furthermore, radium content in the host rock, degree of weathering and fracturing and the emanation coefficient of the rock were found to have an important bearing on the occurrence of radon in groundwater. The underlying factors influencing the abundance of radon in hard rock aquifers were also conceptualized. Thus, the study highlights the usefulness of 222Rn as a potential tool in delineating the macro-structural features like fractures/lineaments that are significant repositories of groundwater, which could be explored for groundwater development in hard rock terrains.


Assuntos
Água Subterrânea , Radônio , Poluentes Radioativos da Água , Humanos , Índia , Radônio/análise , Rios , Poluentes Radioativos da Água/análise
15.
Sci Total Environ ; 750: 142346, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33182182

RESUMO

The biological effects of low dose-rate radiation exposures on humans remains unknown. In fact, the Japanese nation still struggles with this issue after the Fukushima Dai-ichi Nuclear Power Plant accident. Recently, we have found a unique area in Indonesia where naturally high radiation levels are present, resulting in chronic low dose-rate radiation exposures. We aimed to estimate the comprehensive dose due to internal and external exposures at the particularly high natural radiation area, and to discuss the enhancement mechanism of radon. A car-borne survey was conducted to estimate the external doses from terrestrial radiation. Indoor radon measurements were made in 47 dwellings over three to five months, covering the two typical seasons, to estimate the internal doses. Atmospheric radon gases were simultaneously collected at several heights to evaluate the vertical distribution. The absorbed dose rates in air in the study area vary widely between 50 nGy h-1 and 1109 nGy h-1. Indoor radon concentrations ranged from 124 Bq m-3 to 1015 Bq m-3. That is, the indoor radon concentrations measured exceed the reference levels of 100 Bq m-3 recommended by the World Health Organization. Furthermore, the outdoor radon concentrations measured were comparable to the high indoor radon concentrations. The annual effective dose due to external and internal exposures in the study area was estimated to be 27 mSv using the median values. It was found that many residents are receiving radiation exposure from natural radionuclides over the dose limit for occupational exposure to radiation workers. This enhanced outdoor radon concentration might be as a result of the stable atmospheric conditions generated at an exceptionally low altitude. Our findings suggest that this area provides a unique opportunity to conduct an epidemiological study related to health effects due to chronic low dose-rate radiation exposure.


Assuntos
Poluentes Radioativos do Ar , Poluição do Ar em Ambientes Fechados , Monitoramento de Radiação , Radônio , Poluentes Radioativos do Ar/análise , Poluição do Ar em Ambientes Fechados/análise , Radiação de Fundo , Humanos , Indonésia , Doses de Radiação , Radônio/análise
16.
Artigo em Inglês | MEDLINE | ID: mdl-33322400

RESUMO

222Rn is a specific indoor-type pollutant that represents a primary radiological hazard as a main source of ionizing radiation (IR) for humans. Coal mining creates new sources of gas that are formed over mines. This process can significantly increase the density of radon flux. Therefore, the concentration of radon in a room can increase. We investigated the territory of the Leninsk-Kuznetsky district of the Kemerovo region, which is subject to underground mining. Two groups of residential locations and measuring points of radon flux density were selected to identify the higher emanation relationship of radon and mining-affected areas. The first group (Case group) included subjects located within the territory of the underground mine; the other (Control group) included subjects in an area without mining. Radon flux density in coal mining areas was significantly higher than in the rest of the territory; moreover, the percentage of values in the Case group that had a radon flux density above 80 mBq·m-2·s-1 was 64.53%. For the Case group, 20.62% of residential buildings had a radon concentration above 200 Bq/m3. For the studied area, the radon flux density correlates positively (r = 0.79, p = 0.002) with indoor radon. Additional clastogenic/aneugenic effects are also found in dwellings with increased volume activity of radon (VAR) within the territories of underground mines. Ring chromosomes are positively correlated with radon levels in smoker groups but not in non-smokers. An increased frequency of binucleated (BN) cells with micronuclei (MN) is also positively correlated with VAR regardless of smoking status. It has been concluded that reducing the total exposure level of a population to radon can be achieved by monitoring areas with underground mines where radon is emitted heavily.


Assuntos
Poluentes Radioativos do Ar , Monitoramento de Radiação , Radônio , Poluentes Radioativos do Solo , Adulto , Poluentes Radioativos do Ar/análise , Humanos , Masculino , Pessoa de Meia-Idade , Mineração , Radônio/análise , Solo , Poluentes Radioativos do Solo/análise
17.
Artigo em Inglês | MEDLINE | ID: mdl-33379145

RESUMO

A comprehensive study was carried out to measure indoor radon/thoron concentrations in 78 dwellings and soil-gas radon in the city of Mashhad, Iran during two seasons, using two common radon monitoring devices (NRPB and RADUET). In the winter, indoor radon concentrations measured between 75 ± 11 to 376 ± 24 Bq·m-3 (mean: 150 ± 19 Bq m-3), whereas indoor thoron concentrations ranged from below the Lower Limit of Detection (LLD) to 166 ± 10 Bq·m-3 (mean: 66 ± 8 Bq m-3), while radon and thoron concentrations in summer fell between 50 ± 11 and 305 ± 24 Bq·m-3 (mean 115 ± 18 Bq m-3) and from below the LLD to 122 ± 10 Bq m-3 (mean 48 ± 6 Bq·m-3), respectively. The annual average effective dose was estimated to be 3.7 ± 0.5 mSv yr-1. The soil-gas radon concentrations fell within the range from 1.07 ± 0.28 to 8.02 ± 0.65 kBq·m-3 (mean 3.07 ± 1.09 kBq·m-3). Finally, indoor radon maps were generated by ArcGIS software over a grid of 1 × 1 km2 using three different interpolation techniques. In grid cells where no data was observed, the arithmetic mean was used to predict a mean indoor radon concentration. Accordingly, inverse distance weighting (IDW) was proven to be more suitable for predicting mean indoor radon concentrations due to the lower mean absolute error (MAE) and root mean square error (RMSE). Meanwhile, the radiation health risk due to the residential exposure to radon and indoor gamma radiation exposure was also assessed.


Assuntos
Poluentes Radioativos do Ar , Poluição do Ar em Ambientes Fechados , Monitoramento de Radiação , Radônio , Poluentes Radioativos do Ar/análise , Poluição do Ar em Ambientes Fechados/análise , Habitação , Irã (Geográfico) , Radônio/análise , Produtos de Decaimento de Radônio/análise
18.
Environ Monit Assess ; 192(12): 764, 2020 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-33200258

RESUMO

Indoor radon (222Rn) measurements were carried out using solid state nuclear track detectors (SSNTD) in some dwellings from southwestern Nigeria. This was aimed at statistically assessing influence of building characteristics on the measured radon and estimating excess lifetime cancer risks (ELCR). The measured radon concentrations followed lognormal distribution and were significantly influenced by some building properties. The arithmetic mean (1.60 mSv) of annual effective doses (AEDs) due to indoor radon was observed to be higher than the world average level (1.15 mSv) but less than lower limit (3 mSv) of International Commission on Radiological Protection (ICRP). The evaluated excess lifetime cancer risk ranged from 1.5 to 28.1 (MPy)-1 with an average value of 6.3 (MPy)-1, indicating that after exposure to indoor radon for 70 years, 6 people in every 1000 are likely to suffer the risk of developing lung cancer. Adequate ventilation systems were recommended for houses with high level of radon to avoid unnecessary exposure to radon. However, the investigated data would form important component of the database required to set up guidelines and policy of controlling radon at home.


Assuntos
Poluentes Radioativos do Ar , Poluição do Ar em Ambientes Fechados , Monitoramento de Radiação , Radônio , Poluentes Radioativos do Ar/análise , Poluição do Ar em Ambientes Fechados/análise , Monitoramento Ambiental , Habitação , Humanos , Nigéria , Radônio/análise
19.
J Environ Radioact ; 222: 106335, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32892900

RESUMO

Some unexpected sporadic increases of an environmental radioactive background have been recorded at mountain level at Baksan Neutrino Observatory (BNO, 1700 m above sea level) using electron-neutron detectors (en-detectors), which could be explained by radioactive aerosol enhancements. The large area inorganic scintillator en-detectors developed for cosmic ray study are continuously monitoring environmental thermal neutron fluxes at various geophysical conditions. Application of the pulse shape discrimination method allows us to select and separately measure both thermal neutrons and radioactive beta-decay nuclides being products of radon decays in air (mostly Rn-222 and Rn-220). There are two en-detector setups running now at BNO, one deep underground while another one at surface. Both installations had recorded some strange sporadic increases of radioactive nuclides in air. In this paper, we present results and the most probable explanation of the significant increases joint by radioactive aerosols production but caused by different reasons: Baksan river floods or nearby underground experiment with powerful Cr-51 radioactive source.


Assuntos
Aerossóis , Poluentes Radioativos do Ar , Monitoramento de Radiação , Radônio , Poluentes Radioativos do Ar/análise , Radônio/análise
20.
Environ Sci Pollut Res Int ; 27(34): 43389-43395, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32965644

RESUMO

Radon exhaled from building material surfaces is an important source of indoor radon. Yangjiang, located in the southern part of mainland China, is well-known as a high background radiation area (HBRA). Rather, high levels of radon and thoron concentration have been observed in adobe and brick houses. Reducing the indoor radon concentration remains an important issue in the high background radiation areas of China and the world. Generally, the walls of Chinese dwellings are solid. In this paper, a simple one-dimensional model for predicting the radon diffusion in a cavity wall is proposed, and an analysis formula describing the radon exhalation rate from cavity wall surfaces is presented. The influence on the radon exhalation rate due to leakage through structural joints and building material cracks is analyzed. The simulation results indicate that the radon exhalation rate from a cavity wall surface is far lower than that from a solid wall. The structure of cavity walls themselves is therefore useful as a mechanism for reducing the indoor radon in high background radiation areas across the world.


Assuntos
Poluentes Radioativos do Ar , Poluição do Ar em Ambientes Fechados , Monitoramento de Radiação , Radônio , Poluentes Radioativos do Ar/análise , Poluição do Ar em Ambientes Fechados/análise , Radiação de Fundo , China , Materiais de Construção , Expiração , Habitação , Radônio/análise
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