National radon programmes and policies: the RADPAR recommendations.

Results from epidemiological studies on lung cancer and radon exposure in dwellings and mines led to a significant revision of recommendations and regulations of international organisations, such as WHO, IAEA, Nordic Countries, European Commission. Within the European project RADPAR, scientists from 18 institutions of 14 European countries worked together for 3 y (2009-12). Among other reports, a comprehensive booklet of recommendations was produced with the aim that they should be useful both for countries with a well-developed radon programme and for countries with little experience on radon issues. In this paper, the main RADPAR recommendations on radon programmes and policies are described and discussed. These recommendations should be very useful in preparing a national action plan, required by the recent Council Directive 2013/59/Euratom.

Indoor radon in a Spanish region with different gamma exposure levels.

In the beginning of 1990s within the framework of a national radon survey of more than 1500 points, radon measurements were performed in more than 100 houses located in Galicia region, in the Northwest area of Spain. The houses were randomly selected only bearing in mind general geological aspects of the region. Subsequently, a nationwide project called MARNA dealt with external gamma radiation measurements in order to draw a Spanish natural radiation map. The comparison in Galicia between these estimations and the indoor radon levels previously obtained showed good agreement. With the purpose of getting a confirmation of this relationship and also of creating a radon map of the zone, a new set of measurements were carried out in 2005. A total of 300 external gamma radiation measurements were carried out as well as 300 measurements of 226Ra, 232Th and 40K content in soil. Concerning radon, 300 1-m-depth radon measurements in soil were performed, and indoor radon concentration was determined in a total of 600 dwellings. Radon content in soil gave more accurate indoor radon predictions than external gamma radiation or 226Ra concentration in soil.

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.

Conversion factors for external gamma dose derived from natural radionuclides in soils.

Field in situ gamma radiation exposure rates and laboratory measured radioactivity contents of 1500 Spanish soils were compared. The main objective was to determine if published theoretically derived conversion factors would yield accurate quantitative activity concentration (Bq kg(-1)) for the data carried out in different surveys developed by our laboratory during the last ten years. The in situ external gamma dose rate results were compared to laboratory gamma analysis of soils samples gathered from each site, considering the concentrations of seven radionuclides: 40K, 214Pb, 214Bi, 212Bi, 212Pb, 208Tl and 228Ac. The coefficient of correlation found between these variables indicate a good relationship. A discussion of the factors contributing to the uncertainties as well as measurement procedure are also given in this paper.

Results of a simple intercomparison of natural radioactivity measurements using a 'blue concrete' sample.

A simple intercomparison of natural radioactivity and radon emanation factor measurements co-ordinated by the Medical Physics Department of the University of Cantabria UC, Spain, has been carried out during 1998 in the framework of the EU Concerted Action ERRICCA (European Research into Radon in Construction Concerted Action). All the measurements have been made on a 'blue concrete' sample kindly donated by Dr G. Akerblom from the Swedish Radiation Protection Institute. In addition to UC, two other participant laboratories, STUK from Finland and ZVD from the Republic of Slovenia, have contributed to the development of the intercomparison exercise. Considering the uncertainties of the measurements, a good agreement between the results obtained by the three participating laboratories has been ascertained. However, in accordance with experimental results obtained by other authors, data reported by UC show a significant decrease of the radon emanation factor as moisture content of the sample decreases below 5% (per weight).

Influence of low doses of radiation due to 222Rn on proliferation of fibroblasts and MCF-7 human breast cancer cells in vitro.

The aim of the present study is to analyze the effects of low doses of radiation due to radon (within the range present in the environment) in the proliferation of normal (fibroblasts) and tumoral (MCF-7 human breast cancer cells) mammalian cells. Both fibroblast and MCF-7 cells were incubated in culture media with different levels of radon (doses of 10-15 000 microGy), or non-radon (control). After incubation the number of cells per plate was measured with a hemocytometer. The dissolution of radon in the culture media decreased the proliferation of MCF-7 cells (not the fibroblasts). Within the range of doses used in this experiment, the lowest as well as the highest doses of radiation had the lowest antiproliferative effects. Intermediate doses strongly decreased the number of final cells with respect to those in the control population.

Radioactivity in Spanish spas.

There are large number of spas in Spain and there is a lack of data concerning their radioactivity. The levels of radioactivity in a wide sample of Spanish spas were measured with special attention being paid to the radon and radium concentrations in the water, and to radon concentration in the indoor air of the spas. This study is primarily concerned with the radioactivity of the spas of one region in Spain--Cantabria--and particularly one spa where we measured radon levels in water as high as 824 Bq/l and over 5000 Bq/m3 in the air of the rooms. We then considered a wider sample including virtually all of the radioactive spas in the country. The results indicate that a fairly large number of spas have radon levels in water that are moderately high and they are used for the treatment of diseases without radiation protection measures for patients or staff at the spas.

Natural radioactivity in Spanish soils.

The program of studies and surveys of natural radiation and radioactivity in Spain organized by our research group at the end of the 1980s included a 4-y national survey to determine the concentrations of natural radionuclides in soil. Results obtained from measurements of soil samples collected nationwide at > 900 sampling sites are reported and discussed in this paper. Correlations between absorbed dose rates in air calculated from natural radionuclide concentrations in soil and terrestrial gamma dose rates measured experimentally outdoors are shown for the different autonomous regions of Spain. Assessment is also made of the dose to the Spanish population from outdoor exposure to terrestrial gamma rays.

Short- vs. long-term indoor radon measurements.

The major advantage of short-term vs. long-term indoor Rn measurements is that the information is available rapidly. A study of the results obtained for Rn measurements developed in Spain, employing grab samples and 3-mo alpha-track measurements, is discussed.

A modified Lucas cell for leakage measurement from encapsulated radium sources.

A new method to determine the leakage rate from encapsulated radium sources is proposed. The method is based on the principle of enclosing the source to be tested in a hermetically sealed container and measuring the radon radioactivity growth in the container as a function of time. A cylindrical modified Lucas cell, designed and built in our laboratory, is used for measuring the radon which are done by ZnS(Ag) alpha scintillation counting and can be easily compared with existing standard for leak tests. Results obtained show the applicability of the method for leak testing for radon leakage from sealed radium sources.

[Rn 222 levels at the "Las Caldas de Besaya" spa in Cantabria]. / Niveles de 222Rn en el Balneario Las Caldas de Besaya (Cantabria).

222Rn levels in the water and air of the Las Caldas de Besaya spa have been analysed during a year period. The measured values are high in the indoor air of the spa with maximum concentrations of 10(4)Bq/m3. The dose equivalent for patients and workers resulting to exposure of these radon levels were calculated and compared with the derived from the mean natural radiation.

Natural radioactivity of some Spanish building materials.

The penetrating radiation from 226Ra, 232Th and 40K in conventional building materials has been measured by gamma spectrometry. A simple model is applied to the results to calculate the external radiation dose for people living in a typical Spanish house constructed with these materials. The radioactivity concentrations in the building materials were found to be similar to those reported for other countries. The average specific concentrations of 226Ra, 232Th and 40K for the total of 125 samples analyzed ranged from 5 to 421, 3 to 266 and 11 to 599 Bq kg-1, respectively. The results are examined in the light of standards for indoor exposure adopted by the Federal Republic of Germany and the criteria set up in the OECD/NEA Report, 1979.