Radon Concentration In Dwellings Research Articles

Assessment of exposure to the population of Russia from radon

A model has been developed to assess the dose to the population of Russia from radon. Only measurements of radon concentration in dwellings carried out by integral track method were used in the calculations. Population-weighted average radon concentration in dwellings determined on the basis of the results of indoor surveys for the whole Russian population is estimated to be about 52 Bq m −3. According to the conditions of radon exposure, all the Russian population was divided into two categories: (1) living in high radon-prone zone (10% of total) and (2) living in the moderately hazardous or safe zone (90% of total). Assuming the value of dose conversion factor is equal to 6.1 nSv (Bq h m −3) −1, the annual per caput effective doses in the high and low exposed categories are estimated to be 3.2 and 0.63 mSv, respectively. An estimate of annual collective effective dose to the population in Russia (148,100,000 people) is about 130,000 manSv. The annual per caput effective dose is estimated to be 0.88 mSv. About 1 million people receive annual dose above 10 mSv, including approximately 200,000 people with doses above 20 mSv.

Assessment of exposure to the population of Moscow from natural sources of radiation

A model has been developed to assess exposure to the residents of Moscow, Russia from external (cosmic rays and terrestrial gamma rays) and radon exposures. This model accounts for different factors (demographic, social, materials of buildings, etc.) affecting the exposures considered and is based on contemporary measurement data. Ten administrative districts of Moscow were considered separately with respect to both external and internal exposures to the residents. The population-weighted average radon concentration in dwellings in Moscow, determined on the basis of the results of indoor surveys, is estimated to be about 82 Bq m −3. Current estimates of annual collective effective doses to the residents in Moscow city (8,638,100 people) are (1) 6300 man Sv with a 68% confidence interval of 5900–7300 man Sv from external gamma-exposure and (2) 12,000 man Sv with a 68% confidence interval of 8000–16,000 man Sv from radon. The annual per caput effective dose is estimated to be 0.73 mSv from external gamma-exposure and about 1.4 mSv from radon. About 4300 people (0.05% of total) receive an annual effective dose from radon above 5 mSv.

Assessment of radon-222 concentrations in buildings, building materials, water and soil in Jordan

Monitoring of radon gas ( 222Rn) in Jordan was started in the early 1990s. Since then our radon group at Yarmouk University and others have carried out tens of studies that include measurements of indoor radon, radon in water, radon in soil and radon emanating from building materials. All major cities of Jordan had been surveyed, from the northern city of Irbid down to the southern port city of Aqaba. Most of these studies were carried out by using time-integrated passive radon dosimeters containing CR-39 solid-state nuclear track detectors. In addition to that, an active radon monitor was used to study the seasonal variation of 222Rn in Al-Ruseifa that lies near abandoned phosphate mines and in Amman area. During such a study passive dosimeters were also used. The average radon concentrations in dwellings in Jordanian cities ranged from about 20 to 386 Bq/m 3 with the highest readings exhibited during the winter season around the town of Al-Ruseifa.

Indoor radon concentration forecasting in South Tyrol

In this paper a modern statistical technique of multivariate analysis is applied to an indoor radon concentration data base. Several parameters are more or less significant in determining the radon concentration inside a building. The elaboration of the information available on South Tyrol makes it possible both to identify the statistically significant variables and to build up a statistical model that allows us to forecast the radon concentration in dwellings, when the values of the same variables involved are given. The results confirm the complexity of the phenomenon.

Cost assessment of ventilation and averted dose due to radon in dwellings

The inhalation dose due to radon and its progenies could be averted by ventilation in dwellings; however, on the other hand the increased ventilation augments the heating cost. Therefore a cost–benefit analysis could contribute to optimise the ventilation rate. In our current work we applied our former defined parameters of the optimising procedure to assess the optimised ventilation and radon concentration in dwellings with average parameters. To assess the inhalation dose rates the time-dependent concentrations of all the progenies were calculated in case of periodic and continuous ventilation as well, at three different radon entry rates (5, 10, 20 kBq h −1). The optimal ventilation rates in case of continuous ventilation are 0.22, 0.40 and 0.66 h −1, respectively. By these conditions the optimal radon concentration takes 160–210 Bq m −3. According to the more detailed analysis the periodic ventilation gives, in general, a better solution than the continuous one. The Monte Carlo simulations provided a large uncertainty; therefore, before the practical application of the results the uncertainty should be decreased taken into account the local conditions.

Comparison between short- and long-term measurements of radon concentration in dwellings of upper silesia (Poland)

The results of investigations into radon concentration level in dwellings are considered using activated charcoal canisters and track-etched detectors with due regard for geological structure of underlying strata. The statistic analysis is performed. It is shown that long-term monitoring cannot be substituted by a short-term one.

An overview of an indoor radon study carried out in dwellings in India and Bangladesh during the last decade using solid state nuclear track detectors

This paper reports on radon concentrations in dwellings from fifty different locations of India. The incorporated data were obtained using the passive solid state nuclear track detector technique. The estimated geometric mean value for India is 67.1 Bq m−3. Chuadanga in Bangladesh had the lowest observed indoor radon concentration of 27.3 Bq m−3 and Una in the northern part of India had the highest concentration of 281.5 Bq m−3. This paper discusses the national geometrical mean value in terms of the national geometric mean values of other countries and also in terms of the geological influence. The estimated indoor radon levels are compared with the indoor radon levels as recommended by the International Commission on Radiation Protection (ICRP). It was observed that there are several locations in India where dwellings have higher indoor radon levels than the ICRP recommended value and requires some sort of intervention from regulating authorities. The mean value for indoor radon level given in the report of UNSCEAR 2000 for India needs to be revised.

Cytogenetic analyses in peripheral lymphocytes of persons living in houses with increased levels of indoor radon concentrations

Published data concerning the effects of indoor radon exposure on the frequency of chromosome aberrations in peripheral lymphocytes of residents are contradictory. Possible reasons for this may be the low radon concentration in dwellings and/or the limited number of investigated persons. We therefore studied the relationship of domestic radon exposure and the occurrence of chromosome aberrations in peripheral lymphocytes in 61 persons living in houses with radon concentrations from 80 up to 13,000 Bq/m³. We analyzed 60,000 cells from fluorescence plus Giemsa (FPG)-stained slides. It could be clearly demonstrated that in groups of persons living in dwellings with indoor radon concentrations >200 Bq/m³ the number of cells containing dicentrics and/or centric rings (C_{dic + cr}) (2.45 ± 0.50 × 10^–3) was significantly increased (p < 0.05) in comparison to the control level (1.03 ± 0.15 × 10^–3). However, there was no difference in the mean frequency of C_{dic + cr} between the groups living in dwellings with higher radon concentrations. Using the fluorescence in situ hybridization (FISH) technique for the detection of translocations, we analyzed 23,315 cells in 16 persons of the highest exposed group (>5,000 Bq/m³). The observed frequency of translocations was 3.9 ± 0.64 × 10^–3. In comparison to the control group (2.02 ± 0.18 × 10^–3), there was a slight but not statistically significant increase in the exposed group (P = 0.055). If, however, the age of the examined persons is taken into account, the values are significantly increased (P < 0.05) in the exposed persons older than 40 years in comparison to the age-matched controls. Since most of the translocations were found in stable cells, it is concluded that translocations are also induced in blood-forming tissue and are transmitted to peripheral blood.

Passive integrating radon studies for environmental monitoring in Hamirpur district, Himachal Pradesh, India using solid state nuclear track detectors

Indoor radon studies have been carried out in the environs of some areas of Hamirpur district, Himachal Pradesh, India using LR-115 type II plastic track detector. The area is known for uranium mineralization. The work has been undertaken for the health risk assessments. The annual average radon concentration in dwellings in most of the villages falls in the action level recommended by International Commission on Radiological Protection. The radon values in some of the dwellings exceed the action level and may be unsafe from the health hazard point of view. The seasonal variations and the contribution of building wall materials to the indoor radon in dwellings are also discussed.

Geological and geochemical factors affecting radon concentrations in dwellings located on permeable glacial sediments?a case study from Kinsarvik, Norway

In 1996–1997, indoor radon values of more than 40,000 Bq/m3 and large seasonal and geographical variations in indoor air radon were reported from a residential area located on a highly permeable ice-marginal deposit. Geochemical analyses of bedrock, groundwater and sediments and comparisons between indoor radon values and soil radon values indicate that the indoor radon concentrations in this area are strongly affected by subterranean airflows caused by temperature differences between soil air and atmospheric air. The airflows concentrate the radon-laden soil air towards the topographic highest part of the deposit in winter and towards the topographic lowest part in summer. In areas where subterranean airflows are likely to occur, radon measurements performed both in summer and in winter provide the best estimate of annual average indoor radon concentrations, and assessments of indoor radon concentrations based on single soil gas measurements are not recommended.

Correlation of Radon Concentration Level with Mining and Geological Conditions in Upper Silesia Region

It is established that radon concentration in dwellings is connected with the geological structure of the Upper Silesian Coal Basin, as well as the intensity and the depth of carrying out mining operations. The measurements revealed that radon level is higher in buildings located on outcropped Triassic layers than in those ones on Tertiary and Quaternary sediments. It is shown that the syncline regions are the zones of increased radiation hazard.

Radon level in dwellings and its correlation with uranium and radium content in some areas of Himachal Pradesh, India

LR-115 plastic track detectors have been used to measure indoor radon level in some dwellings of Una district, Himachal Pradesh, India. The annual average radon concentration in dwellings in most of the villages falls in the range of the action level recommended by the International Commission on Radiological Protection. The radon values in some of the dwellings exceed the action level and may be unsafe from the health hazard point of view. The indoor radon values are in general higher in winter than in summer. Uranium, radium and radon exhalation studies have also been carried out in soil samples collected from these areas. A good correlation is obtained between uranium concentration in the soil and indoor radon in dwellings. The soil radon exhalation rate also correlates with the uranium concentration in soil.

Correlation between Rn exposure and 210Po activity in Yugoslavian rural communities

Background: In epidemiological studies investigating radon-related health risk, the radon exposures are often derived from contemporary short-term radon measurements. Recent radon measurements, taken over a period of 1 year in dwellings, are often casually extrapolated and taken to be representative for periods spanning several decades. By simply considering the well-known variability of radon concentrations in dwellings and its sensibility to trivial factors such as living habits or minor changes in the dwelling itself, an amount of skepticism concerning the reliability of this practice should arise. In mining areas, this variability is already well acknowledged since mining conditions, such as ventilation of mine shafts, flooding of mine galleries, etc., are known to be able to change radon concentrations in dwellings built on top of mine shafts for over more than one decade. Methods: This study was conducted in stable rural communities in Yugoslavia. Present radon concentrations were compared to an indicator of past radon concentrations, that is the 210Po activity, fixed on glass surfaces or in the bulk of voluminous materials. Results: In less than 50% of the cases, the past and present radon concentrations agree within a factor of 2. Conclusions: This comparison indicates that even in stable rural communities, deriving past radon concentrations by extrapolating present ones is not a particularly good practice.

Prediction of areas presenting a high radon exhalation potential: A new methodology based on the properties of geological formations and soils

A research program carried out since 1997 produced a methodology for predicting areas with a strong potential for radon exhalation at the soil surface. This methodology is based on a quantification of the Rn exhalation rate, from a precise characterization of the mam local geological and pedological parameters that control the radon source and its transport to the soil/atmosphere interface. It combines a cross mapping analysis of parameters used in a Geographic Information System with a model of the vertical transport of Rn by diffusion trough the soil. This code (TRACHGEO) calculates the radon flux density at the surface as a function of the properties of the rock and the soil. This approach is validated in 4 typical areas with different geological contexts, starting from in situ measurements of radon fluxes and of radon concentrations in dwellings. A lithogeochemic al classificatio n of the geological formations as a function of their U contents and their confrontation to Rn level measurements demonstrate the primordial influence of the U content of the basement on Rn exhalation. This study leads to an initial map of the exhalation potential by assigning a potential class to each lithogeochemistry. Nevertheless, in situ radon measurements reveal a high spatial variability on uraniferous lithologies. Tests made by the TRACHGEO tool show the need to take account of spatial heterogeneity of soils (in addition of geochemistry) to improve the mapping resolution. The TRACHGEO forecasts explain the variability of the Rn exhalation on a larger scale.

The regional distribution of indoor radon concentration in Germany

According to the recommendations of the ICRP and the German Commission on Radiological Protection, areas should be identified where increased radon concentrations in buildings occur more frequently than on the countrywide average. Based on investigations of radon concentration in soil air, the areas of Germany have been classified. Comparing the soil gas classes with the radon concentrations in dwellings, we found that in regions with a soil gas radon concentration of up to 10 kBq/m 3 (about 25% of the total area of Germany), the probability that indoor concentrations above 400 Bq/m 3 occur is in the order of 0.1%; values of more than 1000 Bq/m 3 can be excluded. The assessment of about 20 000 indoor measurements in areas with radon concentrations in soil air in the range between 10 and 100 kBq/m 3 showed that radon concentrations >400 Bq/m 3 occur only in 0.2% of the investigated dwelling stock. However, occurrences of more than 1000 Bq/m 3 cannot be excluded completely. A rather clear increase of the number of dwellings with radon concentrations greater than 400 and 1000 Bq/m 3 has been found in areas with soil gas radon concentration >100 kBq/m 3 (about 6% of the area).

Radon concentration in dwellings in Aomori Prefecture, Japan

To obtain an average dose from 222Rn to the people in Aomori Prefecture where the first Japan"s nuclear fuel cycling facilities are now under construction, we surveyed 222Rn concentrations in 109 dwellings in the Prefecture from 1992 to 1996. The outdoor 222Rn concentrations were also measured in gardens of 15 dwellings. The 222Rn concentrations were measured with passive 222Rn detectors which used a polycarbonate film for counting a-ray and could separate concentrations of 222Rn from 220Rn. Counting efficiencies of the detectors were calibrated with a standard 222Rn chamber in the Environmental Measurement Laboratory in USA and in the National Radiological Protection Board in UK. Geometric means of 222Rn concentration were 13 and 4.4 Bq.m-3 in the dwellings and outdoor, respectively. These values were consistent to nationwide survey results in Japan. The 222Rn concentrations in the dwellings depended on their age. The concentrations were higher in recent dwellings than in older ones. The radiation dose from 222Rn was estimated, taking into account the occupancy factor for inside and outside of dwellings. The annual dose was 0.32 mSv.y-1, and 99% of the dose came from the exposure to 222Rn inside the dwelling.

Comparative studies of health hazard from radon (Rn-222) in two selected lithologic formations in the Suwałki region (in Poland)

The aim of this work was to make a comparison of indoor radon concentrations in dwellings and in soil air in the area of two geological formations in the Suwałki region (Poland). The mean arithmetic airborne concentration was found to be the highest (301 Bq m −3) in the basements of buildings in the gravel and sand areas, whereas in the boulder clay areas it reached 587 Bq m −3. Out of 54 measurements of radon concentrations performed at the ground floor, in eight cases concentrations were found to exceed 200 Bq m −3—permissible radon level in new-built houses in Poland and in three cases these values were even higher than 400 Bq m −3. The highest radon levels were noted in houses with earthen basement floors and with direct entrance from the basement to rooms or kitchens. The mean arithmetic radon concentration in the soil air in the sandy and gravel formations was 39.7 kBq m −3 and in clay formation it was 26.5 kBq m −3. Higher radon levels were also found in the water obtained from household wells reaching 8367 Bq m −3 as compared with tap water (2690 Bq m −3). The mean indoor concentration for the whole area under study was found to be 169.4 Bq m −3, which is higher than the mean value for Poland (49.1 Bq m −3) by a factor of 3.5.

Radon permeability and radon exhalation of building materials

High radon concentrations indoors usually depend on the possibilities of radon penetration from the surrounding soil into the buildings. Radon concentrations in dwellings up to 100 kBq/m 3 were found in some special regions (i.e. Schneeberg/Saxony, Umhausen/Tyrol), where the soil shows a high uranium content and additionally, a fast radon transport in the soil is possible. To reduce the radon exposure of the inhabitants in these ‘radon prone areas’ it is necessary to look for building and insulating materials with low radon permeability. We examined several building materials, like cements, concretes and bricks of different constitutions for their diffusion coefficients and their exhalation rates. The insulating materials, like foils and bitumen were tested also on their radon tightness. The measurements were performed with an online radon measuring device, using electrostatic deposition of 218Po ions onto a surface barrier detector and subsequent alpha spectroscopy. The mean diffusion lengths for the investigated building materials range from lower than 0.7 mm (i.e. for plastic foil), up to 1.1 m for gypsum. The diffusion length R was calculated from the diffusion coefficient D with R= D/λ . If the thickness of the material is more than 3 times the diffusion length, then it is called radon-tight. The mean 222Rn exhalation rates for the building materials varied between 0.05 and 0.4 mBq/m 2s. The samples were investigated as stones, plates, blocks, foils, coatings, powders etc., no statement can be made about working at the construction site of a building. Also the fabrication and processing of the materials has to be considered, because the material characteristics may have changed.

A survey of 222Rn concentrations in dwellings of the town of Metsovo in north-western Greece.

A radon survey has been carried out of indoor radon concentrations in dwellings located in the town of Metsovo, in north-western Greece. To measure indoor radon concentrations, CR-39 detectors were installed in randomly selected houses and were exposed for about 3 mo, during summer and winter. Gamma spectroscopy measurements of the soil's radium content also were performed. The indoor radon concentration levels varied from 17.6 to 750.4 Bq m(-3), while the radium concentration of soil varied from 4.9 to 97.1 Bq m(-3). Seasonal variation of the radon levels and the influence of house features and soil are discussed.

Mapping of Areas with Elevated Indoor Radon Levels in Veneto

CRR, the Venetian Reference Laboratory for Environmental Radioactivity, is developing a map of the areas in Veneto with elevated indoor radon levels. Classification is based on analysis of the territorial distribution of radon concentration in dwellings recorded by means of CR-39 track detectors. Regional territory has been divided in 6.5 × 5.6 km 2 grid rectangles, in each of which at least five houses are monitored yearly. For each rectangle the geometric mean (GM) of five detections and the percentage of dwellings exceeding the reference level (assuming log-normal distribution) are evaluated. Measurements are normalised to ground floor condition, thus not being dependent on distance from soil but on geology and geography only; the ground floor radon value is then referred to the average house type using housing stock data. The methodology adopted is being tested through experimental assessments. Radon levels seem to be fairly well correlated with geology.