Radon in workplaces: first results of an extensive survey and comparison with radon in homes

Extensive radon surveys have been carried out in many countries only in dwellings, whereas surveys in workplaces are rather sparse and generally restricted to specific workplaces/activities, e.g. schools, spas and caves. Moreover, radon-prone areas are generally defined on the basis of radon surveys in dwellings, while radon regulations use this concept to introduce specific requirements in workplaces in such areas. This approach does not take into account that work activities and workplace characteristics can significantly affect radon concentration. Therefore, an extensive survey on radon in different workplaces have been carried out in a large region of Italy (Tuscany), in order to evaluate radon distribution in workplaces over the whole territory and to identify activities and workplace characteristics affecting radon concentration. The results of this extensive survey are compared with the results of the survey carried out in dwellings in the same period. The workplaces monitored were randomly selected among the main work activities in the region, including both public and industrial buildings. The survey monitored over 3500 rooms in more than 1200 buildings for two consecutive periods of ～6 months. Radon concentration was measured by means of passive nuclear track detectors.     

Validation of a geographic information system for the evaluation of the soil radon exhalation potential in South-Tyrol and Veneto, Italy

The PERS (soil radon exhalation potential) project was promoted by ANPA (Italian Environmental Protection Agency) together with the Università Cattolica del Sacro Cuore of Rome: the aim was to produce a geographic information system allowing the discovery of regions with different radon exhalation potential starting from some territorial knowledge. Some environmental measurements were carried out within this project in selected areas in South-Tyrol and Veneto. The measurement of radon in springwater and groundwater as well as in soil gas plays a decisive role for the validation of the algorithm for computing the PERS. Along with technical aspects, a possible use of the PERS method by the Regional Environmental Protection Agencies and by other agencies is discussed with the scope of identifying radon prone areas, as stated in the Italian 'Decreto Legislativo' 26 May 2000, n. 241. Moreover the forecasting power of PERS regarding indoor radon concentration is analysed.     

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).     

Soil gas radon measurements in a region of the Bohemian Massif: investigations in the framework of an Austrian pilot study

Soil gas radon measurements are carried out in a pilot study in three municipalities in Upper Austria. The selected municipalities are characterised by a high radon potential. Sixty measuring sites--well distributed over the region and over the different geological areas--were selected. Additionally, the permeability of the soil was determined where the soil gas samples were taken and at various sites where soil samples were analysed by gamma spectrometry. Long-term soil-gas radon concentration measurements are carried out at several sites to study the long-term behaviour of radon activity concentration in soil, the influence of meteorological parameters and seasonal variations. The final goal of the project is to correlate the collected data with geological data and indoor radon concentration. First results of this ongoing study are presented and discussed.     

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.     

Radon risk in Alpine regions in Austria: risk assessment as a settlement planning strategy

Soil gas radon measurements complement indispensable and well-established radon indoor measurements in Austria. Radon in soil gas is a result of geochemical conditions as well as of geology, mineralogy, geophysics and meteorology. Therefore, geological factors can help to predict potential indoor radon concentrations via soil gas. Soil gas radon measurements in well-defined geological units give an estimate of local and regional radon hazards and build the basis for radon risk maps, which could be used for land-use planning and urban development. The creation of maps makes an important contribution to health care. For this purpose, several research projects were carried out in Austria. On the one hand, a study was already conducted in Lower Austria to determine the influence of meteorological and soil physical parameters on radon concentrations in soil gas and to evaluate soil gas radon concentrations with a radon emanation and migration model. On the other hand, radon measurements on different geomorphologic formations in the Austrian Alps, which are potential settlement areas, are of special interest.     

Regional variations pattern of indoor radon levels in some areas of Punjab and Haryana

The indoor radon concentration levels and their regional variationspattern, for two consecutive half-year periods, in a wide rangeof dwellings of some regions of Punjab and Haryana states havebeen studied. The objective was to find the relation betweenthe variations of indoor radon levels with the sub-soil andlocal geology, type of building materials utilised in the dwellingsof the region. Keeping this in view, indoor radon measurementshave been carried out in the dwellings of 30 villages aroundthe Tusham Ring Complex, Bhiwani district, Haryana, known tobe composed of acidic volcanics and associated granites, alongwith 11 villages of Amritsar District, Punjab. The indoor radonconcentration in the dwellings around Tusham (Haryana) was foundto vary from 120 ± 95 to 915 ± 233 Bq m^–3,whereas radon levels varied from 60 ± 37 to 235 ±96 Bq m^–3 for the dwellings studied in Punjab. We believethat local geology including embedded granitic rocks, and sub-soil,as well as building materials having higher radioactive content,is the major contributor for the higher indoor radon levelsobserved particularly in the dwelling around Tusham Ring complex,where some dwellings are showing higher radon concentrationsthan the ICRP recommendations. The environmental samples fromsome areas of Punjab state and around the Tusham Ring Complexof Haryana state have also been analysed for radon exhalationstudies. Higher values for radon exhalation rates have beenobserved for the Tusham's soil/rock specimens, as compared withsoil samples of the Amritsar region of Punjab.     

Indoor radon concentration in the rural dwellings of Chhattisgarh state (India)

Inhalation of radon and its daughter products is the major contributor to the total exposure of the population to natural radiation. An indoor radon survey has been carried out in the state of Chhattisgarh (80.26 degrees N to 84.41 degrees N and 17.8 degrees E to 24.1 degrees E), India under the national coordinated radon project of the Department of Atomic Energy. In the frame of this project indoor radon concentration has been measured in 105 dwellings situated in different villages of Chhattisgarh state. Houses were selected for measurements to cover the most common type of houses generally existing in the rural areas. Measurements have been done on quarterly integrating cycle for one full year in each dwelling using radon cup dosemeter employing LR-115, type-II (pelliculable), solid-state nuclear track detectors. The gamma radiation level was also checked in each dwelling using a gamma survey meter. It was found that the annual average indoor radon concentration in these dwellings varies from 9.91 to 87.84 Bq m(-3) with overall mean value of 26.48 Bq m(-3). Gamma level in these rural dwellings varies from 14.84 to 26.56 microR h(-1) with mean value of 18.68 microR h(-1). We observed that the radon concentration is relatively higher in the houses where the floor is bare but relatively lower in those houses where the floor is tiled or cemented.     

Assessment of long-term radon concentration measurement precision in field conditions (Serbian Schools) for a survey carried out by an international collaboration

In an international collaboration, a long-term radon concentration survey was carried out in schools of Southern Serbia with radon detectors prepared, etched and read-out in Italy. In such surveys it is necessary to evaluate measurement precision in field conditions, and to check whether quality assurance protocols were effective in keeping uncertainties under control, despite the complex organisation of measurements. In the first stage of the survey, which involves only some of the total number of municipalities, paired detectors were exposed in each monitored room in order to experimentally assess measurement precision. Paired passive devices (containing CR-39 detectors) were exposed for two consecutive 6-month periods. Two different measurement systems were used to read out CR-39s of the first and second period, respectively. The median of the coefficient of variation (CV) of the measured exposures was 8 % for 232 paired devices of the first 6-month period and 4 % for 242 paired devices of the second 6-month period, respectively. This difference was mainly due to a different track count repeatability of the two read-out systems, which was 4 and 1 %, respectively, as the median value of CV of repeated countings. The in-field measured precision results are very similar to the precision assessed in calibration conditions and are much lower than the room-to-room variation of radon concentration in the monitored schools. Moreover, a quality assurance protocol was followed to reduce extra-exposures during detector transport from Rome to schools measured and back.     

Radon programme: presence and future

An overview of radon programme experience is presented. The paper summarises broad topics concerning radon issue: philosophy of radon policy, radon measurements strategies with respect to indoor radon variation, progress in radon measurement of an individual house (radon diagnosis), national programmes, the role of preventive measures and interventions with respect to existing and future exposure and knowledge of radon risk, problems of remediation strategies, radon mapping process and sense of delineation of radon prone areas, public awareness on radon issue and publicity campaign. Some research activities are proposed aiming at effective solutions for radon issues in the future.     

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 index of a local administrative unit

The determination of radon-prone areas is usually based on indoor radon data and on the prognosis of the occurrence of houses exceeding the action level. However, the sample of houses in the survey must be representative and large enough, which is not easy to fulfill. Despite this, the determination of localities with high radon risk is useful not only for planning of indoor radon surveys, but also mainly for predicting the risk in newly built houses. There exist two more sources of data that can be used when assigning radon-related index to territories: soil gas radon measurements and gamma dose rate maps, both having their own inaccuracies. An attempt has been made to combine Czech indoor radon data, soil gas radon data and gamma dose rate maps for municipalities, where available. The radon-related index has been constructed by means of statistical analysis (linear regression). The equations found can be used for predicting the radon risk of the municipalities where the data sets are not large enough.     

Radon prevention in new construction in Finland: a nationwide sample survey in 2009

The building code for radon prevention and the associated practical guidelines were revised in Finland in 2003-2004. Thereafter, preventive measures have become more common and effective and indoor radon concentrations have been markedly reduced. In this study, the indoor radon concentration was measured in 1500 new low-rise residential houses. The houses were randomly selected and represented 7 % of the houses that received building permission in 2006. The average radon concentration of all the houses measured, which were completed in 2006-2008, was 95 Bq m(-3), the median being 58 Bq m(-3). The average was 33 % lower than in houses completed in 2000-2005. The decrease was 47 % in provinces with the highest indoor radon concentration and 26 % elsewhere in the country. In houses with a slab-on-ground foundation that had both passive radon piping and sealing measures carried out using a strip of bitumen felt in the joint between the foundation wall and floor slab, the radon concentration was on average reduced by 57 % compared with houses with no preventive measures. Preventive measures were taken nationwide in 54 % of detached houses and in provinces with the highest radon concentration in 92 % of houses.     

Variation of soil radon concentrations in southern Ontario

Radon has been identified as the second leading cause of lung cancer after tobacco smoking. Information on indoor radon concentrations is required to assess the lung cancer burden due to radon exposure. However, radon data in highly populated southern Ontario are very limited. Since radon in soil is believed to be the main source of radon in homes, measurements of soil gas radon concentrations can be used to estimate variations in radon potential of indoor environments. This study reports a transect survey of natural background variation in soil radon levels across southern Ontario. The results indicate that radon risk could be high in some areas of southern Ontario.     

Monitoring for exposures to TENORM sources in Vojvodina region

TENORM are found in a wide variety of waste materials, some raw mineral ores and in some consumer products (in trace amounts) where molecules of radionuclides may be bound to specific minerals used in the manufacturing process and can result in increases in radiation exposures to workers and the public. The aim of this paper is to understand this problem and to develop effective ways to protect humans and the environment from harmful exposure to the radiation in TENORM materials in the Vojvodina region. The results of measurement of indoor radon concentration in schools and kindergartens and dose-rate and gamma-spectrometry measurements of the workplace with TENORM materials are presented.     

Workplace monitoring for exposures to radon and to other natural sources in Europe: integration of monitoring for internal and external exposures

Part of the action of the EURADOS working group (European Radiation Dosimetry Group) on "Harmonisation of Individual Monitoring in Europe" was to investigate how the results from personal dosemeters for external radiation, from monitoring for internal exposure and from workplace monitoring, can be combined into a complete and consistent system of individual monitoring. To facilitate this work, the "EURADOS questionnaire Q3" relating to radon and other natural sources of radiation in the workplace was distributed to relevant institutes across Europe. A total of 24 countries replied to the questionnaire. This study offers an important overview on actual regulations, national standards and reference levels for protection of employees from radon and other natural sources in different workplace scenarios. Information was also collected on individual monitoring and area monitoring to determine individual doses in workplaces with elevated levels of natural radiation. The article discusses in detail the results obtained showing by country the reference level in workplaces for radon gas and other natural sources. In both instances, exposures in mines, other underground workplaces, industry workplaces/waterworks, offices, schools and day-care homes were considered. The resultant data clearly indicate that there is a need for harmonisation among countries, not least in the areas of regulation and use of reference levels in the workplace.     

Indoor radon concentration measurement in the dwellings of Al-Jauf region of Saudi Arabia

Indoor radon concentration measurement in the dwellings of Al-Jauf region of Saudi Arabia was carried out using passive radon dosemeters. The objective of this radon survey was to obtain representative indoor radon data of Al-Jauf region. The study is a continuation of radon survey in main cities of Saudi Arabia which constitutes a baseline for Saudi Arabia in the Radon World Atlas. A total of 318 passive radon dosemeters were distributed randomly in the region and placed for a period of 1 y starting from April 2004 to April 2005. The results of indoor radon concentration measurement in 136 dwellings distributed in Al-Jauf region are presented. The remaining dosemeters were lost in the dwellings or mishandled. The results showed that the average, minimum, maximum radon concentrations and standard deviation were 35, 7, 168 and 30 Bq m(-3), respectively. Geometric mean and geometric standard deviation of the radon distribution were found to be 28 and 1.83, respectively.     

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.     

Analysis of the main factors affecting the evaluation of the radon dose in workplaces: the case of tourist caves

High concentrations of radon exist in several workplaces like tourist caves mainly because of the low ventilation rates existing at these enclosures. In this sense, in its 1990 publication, the ICRP recommended that high exposures of radon in workplaces should be considered as occupational exposure. In developed caves in which guides provide tours for the general public great care is needed for taking remedial actions concerning radon, because in some circumstances forced ventilation may alter the humidity inside the cave affecting some of the formations or paintings that attract tourists. Tourist guides can work about 1900 h per year, so the only option to protect them and other cave workers from radon exposure is to apply an appropriate system of radiation protection mainly based on limitation of exposure by restricting the amount of time spent in the cave. Because of the typical environmental conditions inside the caves, the application of these protecting actions requires to know some indoor air characteristics like particle concentration, as well as radon progeny behaviour in order to get more realistic effective dose values In this work the results of the first two set of radon measurements program carried out in 10 caves located in the region of Cantabria (Spain) are presented.     

Seasonal variation of indoor radon concentration in dwellings of Alexandria city, Egypt

Inhalation of radon ((222)Rn) and daughter products are a major source of natural radiation exposure. Keeping this in view, seasonal indoor radon measurement studies have been carried out in 68 dwellings belonging to 17 residential areas in Alexandria city, Egypt. LR-115 Type 2 films were exposed for four seasons of 3 months each covering a period of 1 y for the measurement of indoor radon levels. Assuming an indoor occupancy factor of 0.8 and a factor of 0.4 for the equilibrium factor of radon indoors, it was found that the estimated annual average indoor radon concentration in the houses surveyed ranged from 45 ± 8 to 90 ± 13 Bq m(-3) with an overall average value of 65 ± 10 Bq m(-3). The observed annual average values are greater than the world average of 40 Bq m(-3). Seasonal variation of indoor radon shows that maximum radon concentrations were observed in the winter season, whereas minimum levels were observed in the summer season. The season/annual ratios for different type of dwellings varied from 1.54 to 2.50. The mean annual estimated effective dose received by the residents of the studied area was estimated to be 1.10 mSv. The annual estimated effective dose is less than the recommended action level (3-10 mSv y(-1)).