Natural Radioactive Gas Research Articles

The potential health hazard due to elevated radioactivity in old uranium mines in Dolina Białego, Tatra Mountains, Poland

Natural radioactivity is one of the essential components of the environment. Unlike the Sudety mountains area in Poland, the Tatra Mountains were not the subject of wide survey as regards the levels of natural radioactivity. Especially, the concentrations of radon (natural radioactive gas) have not been investigated there in terms of their possible negative health impact. Within the frame of bilateral cooperation between the Institute of Nuclear Physics in Kraków, Poland, and the Jožef Stefan Institute in Ljubljana, Slovenia, the measurements of natural radioactive elements in old uranium mines in the Tatra National Park were performed in June 2010. The investigated sites were located in Dolina Białego (The Valley of the White). One of the mines is situated near the tourist path. The paper presents the results of complex measurements of natural radioactivity in both uranium drifts. The concentration of radon gas inside the mining drifts exceeded 28,000 Bq m−3. Also, very high gamma dose rates were observed (up to 5600 nSv h−1). The maximum concentrations of natural radioactive elements (potassium 40K, radium 226Ra, thorium 232Th) in rock samples amounted to 535, 2137, and 18 Bq kg−1, respectively. The effective dose rates due to radon and thoron inhalation have been assessed as 0.013 mSv h−1 (for the lowest concentration) and 0.121 mSv h−1 (for the highest concentration).

Residential radon exposure in some areas of Bangalore city, India

Background: Two isotopes, 222 Rn and 220 Rn of the natural radioactive gas radon are generally of radiological importance. About half of the total radiation effective dose to the general public is due to the irradiation of the lungs by alpha particles following the inhalation of radon decay products. In view of this, 222 Rn and 220 Rn measurements were carried out for a period of 1 year in about 50 dwellings belonging to different residential areas of Bangalore city. The results obtained were systematically analysed and discussed. Materials and Methods: 222 Rn and 220 Rn measurements were carried using Solid State Nuclear Track Detectors. The gamma exposure rate measurements were also carried out in all the dwellings using a G M tube based Environmental Radiation Dosimeter. Results: The concentration of 222 Rn and 220 Rn was found to be highest in the dwellings having mud flooring (Bare) and lowest in the dwellings having mosaic flooring. The geometric mean values of the concentrations of 222 Rn and 220 Rn were found to be 24.1 ± 8.3 and 24.5 ± 10.8 Bq m -3 respectively. The annual mean value of the gamma absorbed dose rate is found to be 175.8 nGy y -1 . Conclusion: The mean value of radon concentration is well within the indian average (42 Bq m -3 ) and world average (40 Bq m -3 ) values. The mean effective dose was found to be 1.19 mSv y -1 and is well within the action level as prescribed by ICRP-65.

A geostatistical approach to define guidelines for radon prone area identification

Radon is a natural radioactive gas known to be the main contributor to natural background radiation exposure and the major leading cause of lung cancer second to smoking. Indoor radon concentration levels of 200 and 400 Bq/m3 are reference values suggested by the 90/143/Euratom recommendation, above which mitigation measures should be taken in new and old buildings, respectively, to reduce exposure to radon. Despite this international recommendation, Italy still does not have mandatory regulations or guidelines to deal with radon in dwellings. Monitoring surveys have been undertaken in a number of western European countries in order to assess the exposure of people to this radioactive gas and to identify radon prone areas. However, such campaigns provide concentration values in each single dwelling included in the sample, while it is often necessary to provide measures of the pollutant concentration which refer to sub-areas of the region under study. This requires a realignment of the spatial data from the level at which they are collected (points) to the level at which they are necessary (areas). This is known as change of support problem.In this paper, we propose a methodology based on geostatistical simulations in order to solve this problem and to identify radon prone areas which may be suggested for national guidelines.

Geological controls on radon potential in Scotland

Synopsis 222 Rn, a natural radioactive gas produced by the radioactive decay of 238 U, accounts for about 50% of the total radiation dose to the average person in the UK. Geology is the most important factor controlling the source and distribution of radon; which has been linked to an increased risk of lung cancer. In order to prevent the public receiving high exposures to radon, it is necessary to identify those areas most at risk. We present results of new mapping of radon potential for Scotland using a method that allows the spatial variation in radon potential to be delineated both within and between geological groupings. The main geological and geochemical associations with moderate to high radon potential areas are described. The highest radon potential values in Scotland are associated with U-rich, highly evolved Siluro-Devonian biotite granite intrusions, notably those clustered within a zone to the west of Aberdeen and at Helmsdale, in Caithness. U mineralization plays a role in areas including the Helmsdale granite and the Middle Old Red Sandstone of the Orcadian Basin. Elevated radon potential is also associated with limestones – where fracture permeability is influential – and with Ordovician–Silurian greywackes. The radon potential of unconsolidated deposits, and how this affects the radon potential of the underlying bedrock, reflects both their permeabilities and their compositions.

Health effects of radon: A review of the literature

Purpose: Radon is natural radioactive noble gas that can be found in soil, water, outdoor and indoor air. Exposure to radon accounts for more that 50% of the annual effective dose of natural radioactivity. The purpose of the current review is to summarize recent literature and evaluate the weight of evidence on the adverse health effects of radon.Conclusions: Radon is an established human lung carcinogen based on human epidemiological data supported by experimental evidence of mutagenesis studies in cell culture and laboratory animals. Extrapolation from cohort studies on miners suggested that radon is the second leading cause of lung cancer death after tobacco smoke. The majority of studies on the relationship between radon and other types of cancers showed weak or no association. Low levels of radon can be found in drinking water; however, radon released during water usage adds small quantities to indoor radon concentration. Studies showed that the risk of stomach cancer and other gastrointestinal malignancies from radon in drinking water is small. Studies of the genetic and cytogenetic effects of indoor radon yielded equivocal results; while radon exposure in miners induces gene mutations and chromosomal aberrations. Numerous in vitro cytogenetic studies demonstrated that radon induces different types of genetic and cytogenetic damage that is likely to play a role in radon lung carcinogenesis.

Radon: Sources, Health Risks, and Hazard Mapping

There are three naturally occurring radon (Rn) isotopes: 219Rn (actinon), 220Rn (thoron) and 222Rn, which is commonly called radon. Radon-222 is a natural radioactive gas produced by the radioactive decay of radium (226Ra), which in turn is derived from the radioactive decay of uranium. Uranium is found in small quantities in all soils and rocks, although the amount varies from place to place. 222Rn (radon) occurs in the uranium-238 decay series, has a half-life of 3.82 days and provides about 50% of the total radiation dose to the average person. Radon concentrations1 in outdoor air are generally low (4 to 8 Bq m-3) whilst radon in indoor air ranges from less that 20 Bq m-3 to about 110,000 Bq m-3 with a population-weighted world average of 39 Bq m-3. Country averages range from 9 in Egypt, 20 Bq m-3 in the UK, 46 Bq m-3 in the US, 108 Bq m-3 in Sweden and 140 Bq m-3 in the Czech Republic (1). Radon in soil air (the air that occupies the pores in soil) commonly varies from 5 to 50 Bq L-1 but may be <1 or more than 2500 Bq L-1. The amount of radon dissolved in ground water ranges from about 3 to nearly 80,000 Bq L-1. This synopsis describes the kinds of rocks and unconsolidated deposits that radon is associated with; how radon moves through the ground and into buildings; the associated health risks, and how to produce radon hazard maps. It is an updated summary of (2).

Assessment of environmental radon hazard using human respiratory tract models

Radon is a natural radioactive gas derived from geological materials. It has been estimated that about half of the total effective dose received by human beings from all sources of ionizing radiation is attributed to 222Rn and its short-lived progeny. In this paper, the use of human respiratory tract models to assess the health hazard from environmental radon is reviewed. A short history of dosimetric models for the human respiratory tract from the International Commission on Radiological Protection (ICRP) is first presented. The most important features of the newest model published by ICRP in 1994 (as ICRP Publication 66) are then described, including the morphometric model, physiological parameters, radiation biology, deposition of aerosols, clearance model and dose weighting. Comparison between different morphometric models and comparison between different deposition models are then given. Finally, the significance of various parameters in the lung model is discussed, including aerosol parameters, subject related parameters, target and cell related parameters, and parameters that define the absorption of radon from the lungs to blood. Dosimetric calculations gave a dose conversion coefficient of 15 mSv/WLM, which is higher than the value 5 mSv/WLM derived from epidemiological studies. ICRP stated that dosimetric models should only be used for comparison of doses in the human lungs resulted from different exposure conditions.

The development of the UK radon programme

The natural radioactive gas, radon, is responsible for the largest component of theradiation dose received by the average UK citizen. The risks of exposure to radon havebeen demonstrated and quantified in epidemiological studies of those exposed at work andin the home. In the UK, measures are in place to identify and help control the exposures inthose houses where levels are highest, to limit levels in new buildings and to controlexposures in the workplace. This paper outlines the development of the programme, withespecial reference to the identification and remediation of homes with high radon levels.

Radon-rich waters in Russia

In radon mineral curative waters, according to Russian mineral water classification, the radon concentration should be greater than 185 Bq/l. There are about 30 mineral waters with high levels of radon in Russia. Radon-rich waters have high therapeutic effects. It is proven that natural background radiation stimulates the human immune system. Radon is a natural radioactive gas that has no taste, smell or color. Radon-222 is one of the heaviest elements in the zero groups of inert gases. It is a gaseous radioactive element. All radon isotopes are α-emitters while the transformation of its decay products is accompanied by the emitting of α-or β-particles. The main products of radon decay are short-lived isotopes Po, Pb, Bi, and TL. Belonging to the uranium and thorium decay chain, radon isotopes form directly during the decay of radium isotopes. Therefore the radon concentration depends upon the concentration of its parent's isotope in water and rocks washed by it as well as upon the amount of radon emanation. Loose rocks or rocks with a great number of cracks are characterized by higher radon concentration (zones of tectonic disturbance, weathering crusts, etc.).Crystalline rocks usually have higher uranium concentrations than the average bedrock. Examples of rock types, which often have enhanced uranium concentration >5% ppm U includes the following: granites, syenites, pegmatite, acid volcanic rocks and acid gneisses. In the earth's crust radon migrates either in a gaseous or dissolved state. It can go to the surface without any chemical reaction. Formation of the radon-rich therapeutics waters of Russia has been analyzed, and most of them are genetically connected to crystalline acid rocks that have exceeded uranium-radium mineralization. The radon content in Russia reaches more than 8,000 Bq/l. Radon-rich waters of this type occur in the Altai, Karelia, St Petersburg and Trans-Baikal regions. Another type is connected to geodynamic activity of regions and secondary radioactivity. A well-known example of radon-rich waters of the second type is Pyatigorsk in the North Caucasus. Mixing confined carbon dioxide-hydrogen sulfide water and unconfined groundwater forms radon waters. The radon concentration is 1,170–2,430 Bq/l. The occurrence of radon-rich water deposits in other regions of Russia is described. Further investigation of the radon content in other geological environments will contribute to the environmental safety as well as to the solution to many genetic, hydrogeochronological, paleoreconstructive and prediction problems in hydrogeology.

Gravitational Interaction of Celestial Bodies and neutron flux bursts from Their Surfaces

The gravitational interaction between the Sun and the planetary solar system gives rise to the well-known tidal waves at the planets. The tidal wave originating in the Earth's crust perpetually transforms the microstructure of the Earth's crust leading to a variation of the concentration of natural radioactive gases in the terrestrial air and to changed conditions of their leakage to the Earth's atmosphere. These variations give rise to bursts of thermal and slow neutrons in the vicinity of the Earth's crust, because the radioactive gases are sources of energetic alpha particles that induce neutron production upon the interaction with the nuclei of elements of the Earth's crust and atmosphere. In this work, the idea of neutron production in the ground coat is extended to the other celestial bodies interacting with one another.

Radon and remedial issues

The Government has recognised the significance of exposures in houses to the natural radioactive gas radon and has over the past decade initiated various campaigns in conjunction with NRPB, BRE and local authorities to mitigate its effects. This article explains the principal features of the programme to reduce radon exposures in existing housing, which is based on encouraging occupiers to measure radon levels in their homes and publicising the availability of cheap and effective remedies. The important role is noted of professional groups such as surveyors in the housing market and detailed descriptions provided of the main methods of reducing radon levels and their suitability for particular buildings. The importance of raising radon awareness amongst professionals is noted and sources of further information are provided including technical reports on remedial measures.

Radon emanation measurement using French and Russian track detectors

This paper presents the first results of a new Franco-Russian project: the International Centre for Radon Expertise (I.C.R.E.). The objectives of this center include determining the sources and contents of natural radioactive gases and their radioactive daughters in order to provide protection against radiation for the population and the environment, and trace the migration of radioactive elements in the soil and plants. Passive radon measurement techniques developed in France and in Russia have been used together to conduct preliminary studies. The results of a comparison of the two techniques, applied both in laboratory and outdoors, are also presented. In order to develop the one passive technique that will be used in future studies, the possibility of optimization using various French and Russian detectors has been investigated. Attempts have been made to compare the response of original measurement cells with nuclear track detectors. Comparisons of such track detector responses have been performed at the university of Franche-Comte in France using various radon environmental conditions (atmospheric gas, soil gas and in water).

Methodology to evaluate the radon risk potential: Application in the Kouzbass region

Radon 222 is a natural radioactive gas belonging to the uranium family. A part of the radon formed in earth'crust can migrate to the atmosphere through cracks on fissumes by means of transport mechanism. High levels can increase the risk of lung cancer due to the alpha particles emitted by both radon 222 itself and its decay products (polonium 214 and 218). In this paper we present: 1) a joint research program designed to develop a method for evaluating the radon risk potential for the population; 2) the application of this method in the Kouzbass region in Russia.

The use of the natural radioactive noble gases radon and thoron as tracers for the study of turbulent exchange in the atmospheric boundary layer—Case study in and above a wheat field

The application of the radioactive noble gases radon (222Rn) and thoron (220Rn) as naturally occurring tracer elements for the measurement of turbulent transport in the atmosphere has been studied in a flat river valley in the vicinity of Göttingen. The measuring site was covered with a crop of wheat. The vertical distribution of radon and thoron was measured continuously over the complete vegetation cycle of the crop. A strong dependence of activity concentrations on meteorological conditions could be observed, yielding during up to 50-times higher night maxima of activity concentrations compared to the noon mimima. Eddy diffusivities were calculated for two height intervals inside and above the crop using a combination of thoron and radon data. A comparison with eddy diffusivities obtained above the crop from meteorological data yielded good agreement between both approaches. The tracer method showed, especially inside the crop, where meteorological methods fall short, the best results, caused by the large concentration gradient due to low vertical exchange.

Radon in the surface waters of southwest England and its bearing on uranium distribution, fault and fracture systems and human health

Abstract Radon is a natural radioactive gas produced by the decay of uranium and thorium in rocks and soils. High surface radon concentrations are commonly associated with high levels of uranium in underlying rocks. High radon levels can also occur in groundwater, even in rocks with normal crustal uranium concentrations. The discharge of groundwater via faults and fractures can produce radon anomalies unrelated to the distribution of uranium. The surface distribution of radon is therefore influenced by the distribution of uranium and of transport pathways along faults and fractures. The principal radon isotope (Rn-222, half-life 3.825 days) is capable of migrating significant distances from its source, both as a gas and in solution. In the gaseous form radon can migrate into houses where, in high concentrations, it can represent a health hazard. The distribution of radon in streams in several areas of southwest England has been investigated. The results show a clear association of high radon levels with the uranium-enriched granite of the region, although this may simply reflect the high fracture permeability of the granite rather than its uranium enrichment with a strong influence of major fracture systems. With regard to radon as a potential health hazard, both source and transport pathways must be identified if high-risk areas are to be located. Surveys of radon in surface waters may provide a useful and speedy technique for the broad identification of such areas.

Developing measuring technique in radioprotection for tracking radon 222 “in situ”

Abstract Radon 222 a natural radioactive gas belonging to the decay chain of uranium 238, is the main constituent of atmospheric radioactivity. Tracking its concentration is thus fundamental for radioprotection ( whether in mining developments or housing) uranium and geologic prospecting and crustal deformations observation (particularly those preceding seismic or volcanic occurences). An experimental setup using solid state nuclear track detectors (SSNTD) and a proportional counter is used for taking additional measurements in order to track this gas “in situ”. The low cost of SSNTDs and their easy use enables the entire survey area to be displayed cartographically. Each detector reveals the integrated radioactive activity over a two month period for each experimental area observed on the site. The proportional counter, immediately indicates all variations in the radon emanation level for a given experimental area on the site through its continuous measuring function. These two techniques used jointly reveal the spatial and temporal distribution of radon emanation. An application for radon level estimation in buildings is presented.

Measurement of the Mobility and the Diffusion Coefficient of Ultrafine Radioactive Particles in the Air

Abstract The mobilities and diffusion coefficients of the decay products of a natural radioactive gas, 86Tn220, and of an artificial radioactive gas, 86Kr88, have been measured in filtered air. The study of the mobility of these radioactive ions has demonstrated the presence of four groups of ions, ThB+ and Rb+. Assuming that the different groups of ions correspond to an increase in the dimensions of these ions, it has been found that the agglomeration velocity of the most rapid ions increases with the irradiation of the air. Under the same conditions, measurements have been made of diffusion coefficients of neutral particles.

Determination of Radon and Thoron in Air

THE presence of natural radioactive gases in the atmosphere was first demonstrated more than fifty years ago, and in recent years interest has been renewed in the subject.