[Radiobiological aspects of "hot" particles].
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Accidents↗
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Results for “AIR POLLUTION, RADIOACTIVE”
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[Ecological protection against volley discharges of radon from the installations of radon laboratories].
The authors analyzed the amount of radon waste and decay products discharged into atmosphere from radon laboratory units. Underlying principles of the design of radon escape monitoring and protection devices are considered. Relevant rating and the parameters of the apparatus developed to considerably limit the isotopes escape are presented. The apparatus is adjusted for current devices making radon concentrates.
Absorption↗
Characterization and control of radon-222 and its progeny in buildings.
Indoor exposure to the naturally occurring, short-lived decay products of radon (Rn-222) inside buildings and homes may pose a significant public health problem. Estimates are that as many as 8 million residential buildings may have indoor radon concentrations that exceed the action level recommended by the U.S. Environmental Protection Agency (4 pCi.L-1). This paper examines the sources of radon in buildings and provides an overview of the methods currently available to reduce indoor concentrations of radon and its decay products.
Air Pollutants↗
[Natural radionuclides in the air in areas of industrial pollution].
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Air Pollutants↗
[Influence of impurities on radiolysis of trichlorofluoromethane].
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Air Pollutants, Radioactive↗
[The radioecological lessons of Chernobyl].
This paper presents the results of radioecological studies undertaken within the area exposed to ionizing radiation after Chernobyl disaster. Conclusions are made concerning the major regularities in radionuclide migration within various natural media and action of ionizing radiation on natural and artificial ecosystems. The efficiency of basic protective ecological measures in eliminating the accident consequences has been determined. The contribution of radioecological studies to the elimination of Chernobyl disaster sequences assessed.
Accidents↗
Determination of radon concentrations of the Dikili geothermal area in western Turkey.
For this study, a geothermal area around Izmir-Dikili, located in the western part of Turkey, was chosen as a measuring site and the radon concentrations of environmental samples were determined. Indoor radon monitoring was performed for 3 months in dwellings located in different part of the region using passive CR-39 nuclear track detectors. The radon concentrations of water samples drawn from wells, municipal supplies, village fountains and spas in the area were measured using a liquid scintillation detector (Packard Tri-Carb 2770 TR/SL, A-277001). Soil samples collected from each location were analysed and (226)Ra concentrations were determined using a gamma ray spectrometer connected to an HPGe detector. Annual effective doses from radon inhalation and ingestion were calculated.
Air Pollutants, Radioactive↗
Contribution of 222Rn in domestic water supplies to 222Rn in indoor air in Colorado homes.
The contribution of 222Rn from domestic water wells to indoor air was investigated in a study of 28 houses near Conifer, CO. Air concentrations determined by alpha-track detectors (ATDs) and continuous radon monitors were compared with the predictions of a single-cell model. In many of the houses, the water supply was shown to contribute significantly to levels of indoor 222Rn. The data from the ATD study were augmented with a continuous monitoring study of a house near Lyons, CO. The well water in that house has the highest known concentration of 222Rn in water yet reported (93 MBq m-3). The temporal pattern in the indoor 222Rn concentration corresponds to water-use records. In general, it is difficult to quantify the proportion of indoor radon attributable to water use. Several lines of evidence suggest that the single-cell model underestimates this proportion. Continuous-monitoring data, although useful, are impractical due to the cost of the equipment. We propose a protocol for 222Rn measurement based on three simultaneous integrating radon detectors that may help estimate the proportion of indoor 222Rn derived from the water supply.
Air Pollutants, Radioactive↗
Indoor radon prediction from soil gas measurements.
This study of radon levels in southwest England investigates the correlation between indoor and soil gas radon concentrations and considers the influence of geology, meteorological variables, spatial and depth variations. This paper examines the value of soil gas measurements as an indicator of potential indoor radon concentrations and highlights a number of factors that need to be considered. Only a very weak correlation was obtained between the overall 222Rn concentration in soil gas and inside the home. However, for high soil gas concentrations a stronger correlation with the indoor level was observed. Typically, the soil gas concentration was between a factor of 10 and 1,000 times greater than that indoors. Levels as low as 10 kBq m(-3) in the soil could produce an indoor concentration above the UK action level of 200 Bq m(-3). The moisture content and the inhomogeneity of soil permeability were identified as chiefly responsible for any perturbation of a soil gas concentration associated with a particular geology. Alone, measured soil gas concentrations have only a limited use in the prediction of indoor 222Rn concentrations.
Air Pollutants, Radioactive↗
[Criteria for the assessment of radon potential risk in territories].
The detailed analysis of criteria used in the different countries for an assessment of radon potential risk in territories was made. Such criteria as radon flux density from earth surface, radon concentration in soil air, specific activity of 226Ra in superficial soils were chosen. The analysis has revealed that the most reliable criterion is the value of equilibrium radon concentration in the soil air. The method of measurement of this value is specified.
Air Pollutants, Radioactive↗
Mapping variation in radon potential both between and within geological units.
Previously, the potential for high radon levels in UK houses has been mapped either on the basis of grouping the results of radon measurements in houses by grid squares or by geological units. In both cases, lognormal modelling of the distribution of radon concentrations was applied to allow the estimated proportion of houses above the UK radon Action Level (AL, 200 Bq m(-3)) to be mapped. This paper describes a method of combining the grid square and geological mapping methods to give more accurate maps than either method can provide separately. The land area is first divided up using a combination of bedrock and superficial geological characteristics derived from digital geological map data. Each different combination of geological characteristics may appear at the land surface in many discontinuous locations across the country. HPA has a database of over 430,000 houses in which long-term measurements of radon concentration have been made, and whose locations are accurately known. Each of these measurements is allocated to the appropriate bedrock--superficial geological combination underlying it. Taking each geological combination in turn, the spatial variation of radon potential is mapped, treating the combination as if it were continuous over the land area. All of the maps of radon potential within different geological combinations are then combined to produce a map of variation in radon potential over the whole land surface.
Air Pollutants, Radioactive↗
Temporal and small-scale spatial variability of 222Rn gas in a soil with a high gravel content.
To quantify the small-scale spatial and long-term temporal variability of the 222Rn concentration in a typical soil with a high gravel content, we monitored this radionuclide every week for 1 year, at 0.5 m and 1.0 m depth at nine sampling positions in a 20 x 20-m field, and at the four corners of a 1 x 1-m plot within this field. The data show that the 222Rn soil gas concentrations exhibited a spatial variability which is characterised in the 20 x 20-m field by coefficients of variation from 20 to 30% at 0.5 m depth, and from 15 to 20% at 1.0 m depth. Within the 1 x 1-m plot, these values were at both depths only 5-10%. In the winter months, the 222Rn soil gas concentration was higher at 0.5 m depth compared to that at 1.0 m depth. However, in the summer months, the opposite behavior was observed. Time series analysis of the data showed that the 222Rn concentrations in the soil gas determined at a given position and depth is strongly correlated with the preceding observation at this point. In addition, strong cross-correlations are present between the 222Rn concentration time series observed at different positions and depths. The above results are used to calculate the probability for estimating, within a given deviation, the annual mean 222Rn soil gas concentration from a single measurement on an arbitrary day of a given month at a limited number of sampling positions only. Because the 222Rn concentration in the soil gas can vary considerably even within 1 month, 222Rn measurement obtained only once in a given month (especially in January and February) can not be used to obtain a good estimate of the mean annual radon concentration, even if a large number of samples in the field are taken.
Air Pollutants, Radioactive↗
Geological controls to the indoor radon distribution in southern Belgium.
Soils and rocks are the predominant source of indoor radon (Rn) in southern Belgium. We have studied the correlations between geological features and indoor Rn concentrations using an indoor Rn data set of approx. 1700 short-term measurements. The sediments in the study region are divided into 11 geological series or 43 stages and 16 rock types. The results show a striking relation between indoor Rn concentration and the geological factors.
Air Pollutants, Radioactive↗
Radon concentration in soil gas: a comparison of the variability resulting from different methods, spatial heterogeneity and seasonal fluctuations.
From the end of 1996 through March 1999, the spatial and temporal variability of the soil 222Rn concentration was investigated at a 20 m x 20 m test field with porous soil in 0.5 m and 1.0 m depth at nine positions each and at 1 m x 1 m plots at four positions each. For this, soil gas was collected weekly into evacuated scintillation cells and was analysed subsequently for radon activity. In the 20 m x 20 m field the spatial variability was characterized by coefficients of variation (C.V.) of 26% at 0.5 m, and 13% at 1.0 m depth. Within the 1 m x 1 m plots the C.V. values were 4% and 2%, i.e. within the uncertainty of the method. Time series analysis (TSA) of the soil radon data shows seasonal variations with maximum concentrations in the winter months. Radon concentrations ranged from 6 to 50 kBq m(-3) in 0.5 m depth, and from 8 to 34 kBq m(-3) in 1.0 m depth. Mostly, the concentrations were higher in 0.5 depth than in 1.0 m depth. However, seasonal variation of the 0.5 m to the 1.0 m concentration ratio has been verified by TSA. To test the variability resulting from different methods, additional procedures and instruments were investigated at the 20 m x 20 m field and at a second test field with a different soil type. Soil gas sampling into evacuated scintillation cells was selected as the reference procedure. Soil radon concentrations obtained with the different sampling procedures and detection methods at the 20 m x 20 m field essentially agreed within the limits of uncertainty of the methods tested. At the second test field, i.e. in a largely impermeable soil, deviations up to a factor of two related to the reference procedure were observed.
Air Pollutants, Radioactive↗
Site characterization for radon supply potential: a progress review.
"Radon-resistant" house foundations were developed by 1981, but additional construction costs made it undesirable to require them unless necessary. The survey methods used then were labor-intensive and cost so much that it was impractical to identify "radon-prone" areas by nationwide surveys. A cheaper method was required to show where radon-resistant foundations were needed. Information available in 1981 suggested that unusual soil conditions were needed to produce high radon concentrations in houses. If these conditions could be identified, elevated radon concentration levels could be predicted from soil measurements at a lower cost than a radon-in-housing survey. Recent radon surveys show that near-surface bedrock or clay soils, which cover most of the continent, are radon-prone. The measurement methods cannot be used in these soils. The cost of radon surveys has been greatly reduced over the past 10 y. Radon-prone areas can now be identified by radon surveys at a lower cost than soil measurements, and the cost of radon-resistant foundations has been reduced. These developments have removed most of the financial incentive for developing soil-based site classification methods. The priority task now is to encourage the adoption of radon-resistant foundations in radon-prone areas.
Air Pollutants, Radioactive↗
Effect of soil parameters on radon entry into a building by means of the transrad numerical model.
High indoor radon concentration means an increased risk of developing lung cancer. When high radon levels are present in a dwelling, the major source is normally the soil. Therefore, it is useful to know the radon concentration field in the soil underneath a building. A steady-state two-dimensional radon transport model has been used to calculate the effect of a reference building on the soil radon concentration, and the influence of soil parameters on radon entry through a single crack in the basement. Both advective and diffusive flows are considered. Away from the building, the well-known undisturbed soil radon concentration profile has been obtained, while under the house the radon level is increased. A variability analysis around the reference site has shown that the most relevant soil parameters on the radon flux at the top of the crack are, in this case, effective diffusion coefficient, soil gas-permeability and deep soil radon concentration.
Air Pollutants, Radioactive↗
Radon concentration measurements and personnel exposure levels in Bavarian water supply facilities.
As part of a study covering the whole of Bavaria, the southern most of Germany's 16 states, water supply facilities were examined to determine the radon (222Rn) concentrations in ground water and indoor air and the radon exposure to the staff working in these buildings. Bavaria can be divided into ten geological regions of different geogenic radon potential. From each region, a number of water supply facilities proportional to the size of the region were selected for measurements. Over 500 of a total number of 2,600 water supply facilities were asked to take a 1-L groundwater sample and expose several track-etch detectors in order to obtain the mean room concentration of the main staff work places. In addition, for a period of 2 mo, the personnel had to wear a track-etch detector during the time they spent in the supply facilities. The resulting measurements were then used to estimate their individual effective dose of radon and its progenies. In the East Bavarian crystalline region, the region of the highest geogenic radon potential within Bavaria, indoor radon gas concentrations of up to 400 kBq m(-3) were observed. About 10% of the process controllers in this region are subjected to an annual effective dose of more than 20 mSv. In the other Bavarian regions, only 2% of staff exposure levels exceed this limit. The correlation between the radon concentration measurements of the indoor air, the ground water, and individual personnel exposure levels was determined. The average ratio of the radon indoor air to the processed groundwater concentration is 0.14. But due to the different types of ventilation in the various supply facilities, there can be great variations in this figure. Therefore, there is no clear relationship between the groundwater and the indoor air concentration of a supply facility. This study also reveals no clear relationship between radon indoor air concentrations and the personnel exposure levels of a supply facility.
Air Pollutants, Radioactive↗
Indoor radon in Thailand: a study with particular reference to its sources.
Measurements of radon gas were carried out on each floor of the four tall concrete buildings. The results show clearly that levels of radon concentration on the higher floors of the buildings were mostly comparable and occasionally were much higher than the ground-floor in contact with the earth. Hence, the findings indicate that the source of indoor radon is not only the surrounding soil but also other sources in the buildings, i.e. most likely radium-containing building materials.
Air Pollutants, Radioactive↗