Radiological characterisation of Artvin and Ardahan provinces of Turkey

Indoor radon concentration measurements were carried out and corresponding annual effective doses due to exposure to indoor radon were determined in Artvin and Ardahan provinces located in the eastern part of Turkey. The measurements were performed for four seasons in order to determine the seasonal fluctuations mostly observed in indoor environments. Indoor radon concentration values were observed to range from 21 to 321 Bq m?3 for the Artvin province and from 53 to 736 Bq m?3 for the Ardahan province. It was observed that minimum indoor radon concentration values were obtained in summer, while the highest ones were observed in winter. Indoor radon concentration values of the current study were compared with those of other provinces in Turkey. As elevated indoor radon concentrations are mostly correlated with high 23?U activity concentrations in soil, a total of 57 and 33 soil samples were collected from the Artvin and Ardahan provinces, respectively, to determine 23?U activity concentration as well as the concentration of 232Th and ??K--naturally occurring radionuclides. It was also observed that soil samples collected from the study areas contained 13?Cs as an artificial radionuclide.     

Miners' exposure to radon and its decay products in some Iranian non-uranium underground mines

Measurements of radon, radon decay products and gamma exposure rate in 12 non-uranium underground mines have been carried out in order to estimate the occupational radiation exposure of miners. Continuous measurements of radon using pulse ionisation chambers and scintillation cell techniques were employed for these studies. Progenies of radon were collected on filter paper, and then a three-count procedure was used for the measurement. The equilibrium state between radon and its decay products has been determined. Concentrations of natural radionuclides ((226)Ra, (232)Th and (40)K) in ore and soil samples taken from various locations in each mine have been measured using a Canberra High Purity Germanium detector. Based on these measurements two ranges of dose were evident. Doses ranged from 0.1 to 1.52 mSv y(-1) for nine mines and from 10 to 31 mSv y(-1) for the other three mines. A separate grouping of the mines was recognised from radon concentrations, which varied from 2 Bq m(-3) to 10 kBq m(-3). In three of these mines, working level (WL) concentrations of the order of 36-1771 mWL were determined in different working areas. In all other mines, the concentrations were observed to be <45 mWL.     

Evaluation of radon concentration in well and tap waters in Bursa, Turkey

(222)Rn measurements in water samples collected from 27 wells and 19 taps that were supplied from the investigated wells were conducted using the AlphaGUARD PQ 2000PRO radon gas analyser at sites across several geologic formations within the city of Bursa, Turkey. The measured radon concentrations ranged from 1.46 to 53.64 Bq l(-1) for well water and from 0.91 to 12.58 Bq l(-1) for tap water. Of the 27 sites sampled, only 7 had radon levels above the safe limit of 11.1 Bq l(-1) recommended by the USEPA. In general, all determined concentrations were well below the 100 Bq l(-1) revised reference level proposed by the European Union. These values of radon concentrations in water samples are compared with those reported from other countries. Doses resulting from the consumption of these waters were calculated. The minimum and the maximum annual mean effective doses due to (222)Rn intake through water consumption were 0.02 μSv a(-1) and 1.11 μSv a(-1), respectively.     

Study of a Greek area with enhanced indoor radon concentrations

In this paper the focus is on Arnea Chalkidikis, an area in Greece with granitic geological background and indications of possible elevated radon concentration indoors. Data are reported of indoor radon measurements with etched track detectors and those are used for dosimetric estimations. Moreover, data are reported on soil gas and soil radon concentrations in Arnea, as well as radon and uranium concentrations in water samples. From the measured radon concentrations in water samples the contribution to the overall dose has been calculated. For a period of 1 month, indoor radon and progeny activity has also been monitored in the dwelling that has the maximum indoor radon concentration in Greece. This dwelling is in Arnea and the dose delivered to the inhabitants has been calculated. The mean annual effective dose due to indoor radon was 4.5 mSv and about 11% of this was due to the use of water. Mean soil gas concentration and soil radon concentration were (90 +/- 30) kBq m(-3) (p<0.05) and (30 +/- 5) kBq m(-3) (p<0.05) respectively. Mean uranium concentration of the water samples was (98 +/- 13) mBq l(-1) (p<0.05).     

Hourly indoor radon measurements in a research house

This paper reports and discusses the behaviour of radon concentration with time in an uninhabited dwelling. The relationship between variations in radon concentrations and indoor-outdoor temperatures and wind intensity has also been discussed. Radon concentration was measured hourly in a house located at a height of 800 m in the Lombard Prealps, at the top of the Valassina valley. The wind velocity and indoor-outdoor temperatures were measured by means of a meteorological station located on the terrace of the house. The data were analysed using the LBL model for indoor-outdoor air exchange and the models for the indoor accumulation of radon due to exhalation from building materials and pressure-driven infiltrations located underground. The role of wind and indoor-outdoor temperatures were analysed. The agreement of measurements with modelling clearly demonstrates the importance of the different sources of indoor radon. As the investigation was conducted in an uninhabited house, the measurements were not affected by the behaviour of people, e.g. opening and closing of windows. Measurements of the outdoor atmospheric concentrations of (222)Rn provide an index of the atmospheric stability, the formation of thermal inversions and convective turbulence.     

Effect of Grain Size on Radon Exhalation Rate in the Soils of Hassan District of Southern India

The radon concentration and radon exhalation rates were studied in 39 soil samples collected from Hassan district of southern India. LR-115 Type II solid-state nuclear track detector was used to measure the radon exhalation rate using the sealed can technique. The radon exhalation rate increases with a decrease in the soil grain size. A strong positive correlation was observed between the radon exhalation rate and effective radium content. The α index and annual effective dose were also determined.     

A study of environmental radioactivity measurements for Cankiri, Turkey

This study is the first to assess the level of background radiation for the Cankiri province of Turkey. Indoor air radon concentrations were determined using Columbia Resin-39 nuclear track detectors and the average (222)Rn activity was found to be 44 Bq m(-3) (equivalent to an annual effective dose of 1.1 mSv). Measurements of gamma doses in outdoor air were performed using a portable plastic scintillation detector and the average gamma absorbed dose rate was found to be 8 μR h(-1) (corresponding to an annual effective dose of 87.7 μSv). Radionuclide activity concentrations in soil samples were measured through gamma-ray spectrometry and the average activities were determined as 17.7, 22.3, 357 and 4.1 Bq kg(-1) for the radionuclides (238)U, (232)Th, (40)K and (137)Cs, respectively. The average annual effective dose from the natural radioactivity sources ((238)U series, (232)Th series and (40)K) was calculated to be 44.4 μSv. Radioactivity levels of drinking water samples were carried out using a low-background proportional counter and the average gross alpha and beta activities were obtained as 0.25 and 0.26 Bq l(-1), respectively (equivalent to an annual effective dose of 184 μSv). The average radon concentrations in indoor air and the average radionuclide activities in soil were found to be lower than most Turkish cities while higher levels of outdoor gamma dose rate and water radioactivity were observed. The results of this study showed that the region's background radioactivity level differs considerably from the reported data for Turkish cities.     

Real-time measurement of individual occupational radon exposures in tombs of the Valley of the Kings, Egypt

The active radon exposure meter developed recently at the German Research Center for Environmental Health (Helmholtz Zentrum München) was used to measure radon concentrations in 12 tombs located in the Valley of the Kings, Egypt. Radon concentrations in air between 50 ± 7 and 12 100 ± 600 Bq m(-3) were obtained. The device was also used to measure individual radon exposures of those persons working as safeguards inside the tombs. For a measurement time of 2-3 d, typical individual radon exposures ranged from 1800 ± 400 to 240 000 ± 13 000 Bq h m(-3), depending on the duration of measurement and radon concentration in the different tombs. Based on current ICRP dose conversion conventions for workers and on equilibrium factors published in the literature for these tombs, individual effective dose rates that range from 1.5 ± 0.3 to 860 ± 50 μSv d(-1) were estimated. If it is assumed that the climatic conditions present at the measurement campaign persist for about half a year, in this area, then effective doses up to ～ 66 mSv could be estimated for half a year, for some of the safeguards of tombs where F-values were known. To reduce the exposure of the safeguards, some recommendations are proposed.     

Survey of radon and thoron in homes of Indian Himalaya

Measurements of radon, thoron and their progeny were carried out in some houses from Garhwal and Kumaun Himalayas of India using a LR-115 plastic track detector. The measurements were made in various residential houses of the area at a height of 2.5 m above the ground level using a twin chamber radon dosemeter, which can record the values of radon, thoron and their progeny separately. The concentrations of radon and thoron in these homes were found to vary from 11 to 191 and 1 to 156 Bq m(-3), respectively. The equilibrium factor between radon and progeny varies from 0.02 to 0.90, with an average of 0.26 for the region. The resulting dose rate due to radon, thoron and their decay products was found to vary from 0.02 to 0.84 μSv h(-1) with an arithmetic mean of 0.27 μSv h(-1). A detailed analysis of the distribution of radon, thoron and their decay products inside a house is also reported. The observed dose rates due to radon, thoron and progeny were found somewhat higher but well below the international recommendations.     

Radon hazard and risk in Sussex, England and the factors affecting radon levels in dwellings in chalk terrain

A survey was undertaken of radon levels in 1013 dwellings in Sussex, UK. A number of dwellings were identified with high radon levels in an area previously considered to offer low radon risk from geological sources. Multiple regression was used to determine the relative influence of the various geographical and building-related factors on indoor radon levels. The radon hazard, independent of building-related effects, was determined for each surveyed location by standardising radon measurements to a 'model' dwelling. These were entered into a geographic information system and related to surface geology. The highest radon levels were found to be associated with the youngest Chalk formations, Tertiary deposits and Clay-with-flints Quaternary deposits in the area. Radon potentials were also determined for the area which can be used to estimate radon risk and assist in environmental planning and development control.     

Radon concentration measurements in the Amasra coal mine, Turkey

In this study, the results of atmospheric radon measurements that were performed for the Amasra underground coal mine in Zonguldak bituminous coal basin (Turkey) are presented. The radon measurements were performed for 40 days between November 2004 and December 2004 using passive nuclear etched track detectors. The radon concentrations vary from a minimum value 49 Bq m(-3) in a site located at +40 m to a maximum value 223 Bq m(-3) in a site located at -100 m. Mean concentration is 117 (Bq m(-3)). This value is well below the action level of 500-1,500 Bq m(-3) recommended by the International Commission on Radiological Protection (ICRP) (1993). The mean effective dose value for workers of this mine of 3.4 microSv per day was obtained. This result shows that protection against radiological hazards would not be necessary for workers of this mine((2)).     

Estimates of the dose due to 222Rn concentrations in water

About 300 samples of groundwater were collected in the region of Extremadura (Spain) in order to analyse their radon activity concentrations. Correlations with the geological characteristics of the aquifer soil were studied. Internal doses by inhalation due to radon exhalation from the water sample and doses by ingestion were estimated. A model was used to calculate the lung dose due to inhalation of radon exhaled from the water. The estimated lung dose range found for the samples was from 2.1 x 10(-3) to 13 mSv a(-1) (the average contribution to the dose due to radon inhalation in Spain being approximately 1.2 mSv a(-1)). The estimated dose by ingestion ranged from 4.1 x 10(-4) to 3.3 mSv a(-1).     

High background radiation areas: the case of Villar de la Yegua village (Spain)

The starting point of the Spanish experience in the study of High Background Radiation Areas is the development of a nationwide indoor radon survey carried out in 1988. This campaign, belonging to the first Spanish Radon Framework, consisted of approximately 2000 indoor radon measurements which represented a valuable basis to face rigorously the radon issue in Spain. Together but indepently from this survey, since 1991 the Spanish Nuclear Safety Council, the National Uranium Company and several Universities have developed the so-called MARNA project with the aim of estimating potential radon emission from external gamma dose rates, radium concentrations in soil and geological parameters. During the last decade, several regional surveys have also been conducted to determine exposure to natural sources of radiation in different highly populated background radiation areas. Among them, the surroundings of the village of Villar de la Yegua Town, located in the western province of Salamanca, is the most important area of Spain from a radiological point of view, with the highest indoor radon concentrations, of up to 15,000 Bq m(-3) being found there. Until now, the main result of the study in this area showed a geometric mean radon concentration of 818 Bq m(-3), which is 18 times higher than the national average. In this article, the results of the last survey, carried out in Villar de la Yegua during 2004 are summarised. A geometric mean radon concentration of 1356 Bq m(-3) was found. Dose estimation coming from radon inhalation is also shown.     

Radon measurements by nuclear track detectors in dwellings in Oke-Ogun area, South-Western, Nigeria

An indoor radon survey of a total of 77 dwellings randomly selected in 10 districts in Oke-Ogun area of Oyo state, South-western Nigeria was carried out using CR-39 detectors. The CR-39 detectors were placed in the bedrooms and living rooms and exposed for 6 months and then etched in NaOH 6.25 N solution at 90 °C for 3 h. Mean concentrations amount to 255 ± 47 and 259 ± 67 Bq m(-3) in the living rooms and bedrooms, respectively. The lowest radon concentration (77 ± 29 Bq m(-3)) was found in Igbeti, whereas the highest was found in Okeho (627 ± 125 Bq m(-3)). The annual exposure of dwellers was estimated to fall <10 mSv (6.4 and 6.5 mSv y(-1) n living rooms and bedrooms, respectively), which is the upper range of action levels recommended by the International Commission on Radiological Protection. The average excess lung cancer risk was estimated 24.8 and 25.2 per million person-years in both living rooms and bedrooms. It is believed that the high radon level in this part of the country may be attributed to its geographic location. The data presented here will serve as a baseline survey for radon concentration in dwellings in the area.     

Comparison of urinary excretion of radon from the human body before and after radon bath therapy

Theoretically, the human body absorbs radon through the lungs and the skin and excretes it through the lungs and the excretory organs during radon bath therapy. To check this theory, the radon concentrations in urine samples were compared before and after radon bath therapy. During the therapy, the geometric mean (GM) and the geometric standard deviation of the radon concentration in air and in the bath water were 979 Bq m(-3), 1.58 and 73.6 Bq dm(-3), 1.1, respectively. Since radon was detected in each urine sample (GM around 3.0 Bq dm(-3)), urinary excretion of radon was confirmed. The results of this study can neither reject nor confirm the hypothesis of radon absorption through the skin. A 15 times higher increment of inhaled radon level did not cause significant changes in radon of urine samples.     

Time changeability in radon concentration in one-family dwelling houses in the northeastern region of Poland

Two groups of buildings (29 in total) were examined to assess the time changeability in radon concentrations. All the buildings showed seasonal changes with the individual schemes of radon concentration changeability, which varied together with the changes in outside weather parameters, such as temperature and pressure. Measurements based on several days exposure give values ranging from 0.1 to 3.4 of the annual mean. Monthly measurements of radon concentration presented values from 0.3 to 1.8 of the annual mean. A major part of the examined houses showed negative correlation between the indoor radon concentrations and the outside temperatures, and positive correlation between the radon concentrations and the changes in the atmospheric pressure.     

Effective dose: a useful concept in diagnostic radiology

The long-term monitoring of soil radon variations was conducted at two reference sites in Ottawa. The purpose of this study was to determine whether a single soil radon survey could provide a representative soil radon characteristic of the site. Results showed that during the normal field survey period from June to September in Canada, a single field survey with multiple measurements of soil gas radon concentrations at a depth of 80 cm can characterise the soil radon level of a site within a deviation of +/-30%. Direct in situ soil permeability measurements exhibited, however, large variations even within an area of only 10 x 10 m(2). Considering such large variations and the weight of the equipment, soil permeability can be determined by direct measurements whenever possible or by other qualitative evaluation methods for sites that are hard to access with heavy equipment.     

Radon measurement in schools located in three priority investigation areas in the province of Quebec, Canada

The purpose of this study was to measure radon concentration in public primary schools located in priority investigation areas, with the aim of decreasing occupants' exposure to radon in public buildings where concentrations exceed the Canadian Federal guidelines (i.e. 200 Bq m(-3)). In addition, the association between radon levels, substratum geological characteristics and schools' structural characteristics were investigated. The results showed that radon concentrations measured in the 65 investigated schools are generally below the Federal guideline levels. Eleven schools (17 %) had at least one measurement above the Federal guideline, while one had a level above 600 Bq m(-3). On average, targeted schools' occupants are exposed to radon concentrations of 56 Bq m(-3). Although statistical analysis, which was limited by the sample size, did not show any link between aggregated radon measurements and geochemical or radiological signatures of investigated sites, the geological evidence that led to the choice of the studied regions remains relevant.     

Indoor radon levels in buildings in the Autonomous Community of Extremadura (Spain)

Indoor air samples taken in buildings throughout the provinces of Cáceres and Badajoz in the Autonomous Community of Extremadura, Spain, were analysed for airborne radon concentrations using charcoal canisters. Measurements were made during the years 1998-2000. The geometrical mean indoor concentration was 90 Bq m(-3). An estimated annual effective dose of 1.6 mSv y(-1) was calculated for residents, assuming an equilibrium factor of 0.4 and an occupancy factor of 0.8. The relative importance of the principal variables that condition radon concentrations inside buildings was also delimited experimentally. These were: soil type, construction materials used, the height of the room above ground level, and the degree of ventilation. The temporal evolution of the radon concentration was analysed, as this aspect could be particularly important in a Continental-Mediterranean climate such as that of the two provinces of the study.     

Radon survey in Kalamata (Greece)

A national radon survey is still lacking for Greece. Some groups have carried out several more or less local or extended radon surveys and valuable experience has been gained. After the first preliminary survey carried out by our group, where 500 Kodak LR-115 etched track detectors were placed in Greek schools and dwellings for one year, indoor radon measurements were continued by placing the same number of detectors in a restricted area, covering the city of Kalamata (a medium size city with 60,000 inhabitants), situated in the south of Peloponnese. Although Kalamata was not of special radon interest, the local authorities insisted on knowing for their citizens' sake the level of this natural radiation. At first, the intention was to use a different method of organisation and distribution of the etched-track detectors from the previous one, attempting mainly to acquire more reliable results and to collect as many detectors as possible. Secondly, it was of great importance to test the statistics of the indoor radon concentrations for a rather small area, and thirdly, to estimate independently the annual absorbed dose by children, taking into account radon concentrations measured both in their home and at school. The set of detectors' readings (about 370), revealed, in general, lower values for Kalamata, compared to the ones found in the preliminary radon survey in Greece and almost all concentrations were found to be below the NRPB action level (200 Bq.m-3).