Luis Santiago Quindós

National survey on indoor radon in Spain

A national survey on indoor radon levels in Spain has been carried out by measuring the radon concentration in 1555 randomly chosen houses. Measurements were performed during the winter season of 1988 with complementary measurements in the winter of 1989. Radon in air was determined using modified alpha-scintillation cells under specified conditions in the sampling collection and nuclear track detectors in selected houses. The distribution of indoor radon levels has been found to be approximately log-normal with a geometric mean of 41.1 Bq·m−3 and a standard deviation of 3.0. The highest value of the radon concentration found was 15 400 Bq·m−3 In about 4% of the houses, the radon concentration was found to be in excess of the recently recommended value of 400 Bq·m−3, suggested by the Commission of the European Communities (CEC). Elevated indoor levels were found to be more prevalent in the west and northwest than in the rest of the country. Also shown in this paper is an evaluation of the median effective dose equivalent to the individual in Spanish houses for different regions.

Comparative risk assessment of residential radon exposures in two radon-prone areas, Ştei (Romania) and Torrelodones (Spain)

Radon and radon progeny are present indoors, in houses and others dwellings, representing the most important contribution to dose from natural sources of radiation. Most studies have demonstrated an increased risk of lung cancer at high concentration of radon for both smokers and nonsmokers. The work presents a comparative analysis of the radon exposure data in the two radon-prone areas, Stei, Transylvania, (Romania), in the near of old Romanian uranium mines and in the granitic area of Torrelodones town, Sierra de Guadarrama (Spain). Measurements of indoor radon were performed in 280 dwellings (Romania) and 91 dwellings (Spain) by using nuclear track detectors, CR 39. The highest value measured in Stei area was 2650 Bq m(-3) and 366 Bq m(-3) in the Spanish region. The results are computed with the BEIR VI report estimates using the age-duration model at an exposure rate below 2650 Bq m(-3). We used the EC Radon Software to calculate the lifetime lung cancer death risks for individuals groups in function of attained age, radon exposures and tobacco consumption. A total of 233 lung cancer deaths were observed in the Stei area for a period of 13 years (1994-2006), which is 116.82% higher than expected from the national statistics. In addition, the number of deaths estimated for the year 2005 is 28, which is worth more than 2.21 times the amount expected by authorities. In comparison, for Torrelodones was rated a number of 276 deaths caused by lung cancer for a period of 13 years, which is 2.09 times higher than the number expected by authorities. For the year 2005 in the Spanish region were reported 32 deaths caused by pulmonary cancer, the number of deaths exceeding seen again with a factor of 2.10 statistical expectations. This represents a significantly evidence that elevated risk can strongly be associated with cumulated radon exposure.

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.

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.

Terrestrial gamma radiation levels outdoors in Cantabria, Spain

Terrestrial gamma-ray dose rates have been measured outdoors throughout the region of Cantabria, located in the north of Spain. Results obtained are shown in tabular and cartographical form and are related to the nature of the ground and other influencing factors. The mean absorbed dose rate in air outdoors is 35.46 nGy h-1. The mean annual effective dose equivalent, when the duration of outdoor exposure and distribution of the population are considered, is about 32 mu Sv. This dose is in addition to those doses received from other sources of natural radiation, principally from the presence of radon gas indoors.

Residential radon and cancer mortality in Galicia, Spain

Residential radon exposure is a serious public health concern, and as such appears in the recommendations of European Code Against Cancer. The objective of this study was to assess the association between residential radon levels and mortality due to different types of cancer, using misaligned data analysis techniques. Mortality data (observed cases) for each of the 313 Galician municipalities were drawn from the records of the National Statistics Institute for the study period (1999-2008). Expected cases were computed using Galician mortality rates for 14 types of malignant tumors as reference, with a total of 56,385 deaths due to the tumors analyzed. The effect estimates of indoor radon (3371 sampling points) were adjusted for sociodemographic variables, altitude, and arsenic topsoil levels (1069 sampling points), using spatial/geostatistical models fitted with stochastic partial differential equations and integrated nested Laplace approximations. These models are capable of processing misaligned data. The results showed a statistical association between indoor radon and lung, stomach and brain cancer in women in Galicia. Apart from lung cancer (relative risk (RR)=1.09), in which a twofold increase in radon exposure led to a 9% rise in mortality, the association was particularly relevant in stomach (RR=1.17) and brain cancer (RR=1.28). Further analytical epidemiologic studies are needed to confirm these results, and an assessment should be made of the advisability of implementing interventions targeting such exposure in higher-risk areas.

Description of the behavior of an aquifer by using continuous radon monitoring in a thermal spa.

Radon ((222)Rn) levels in air and water have been analyzed continuously for almost a year in Las Caldas de Besaya thermal spa, north Spain. Radon is a naturally occurring noble gas from the decay of radium ((226)Ra) both constituents of radioactive uranium 238 series. It has been recognized as a lung carcinogen by the World Health Organization (WHO) and International Agency for Research on Cancer (IARC). Furthermore the Royal Decree R.D 1439/2010 of November, 2010 establishes the obligation to study occupational activities where workers and, where appropriate, members of the public are exposed to inhalation of radon in workplaces such as spas. Together with radon measures several physico-chemical parameters were obtained such as pH, redox potential, electrical conductivity and air and water temperature. The devices used for the study of the temporal evolution of radon concentration have been the RTM 2100, the Radon Scout and gamma spectrometry was complementarily used to determine the transfer factor of the silicone tubes in the experimental device. Radon concentrations obtained in water and air of the spa are high, with an average of 660 Bq/l and 2900 Bq/m(3) respectively, where water is the main source of radon in the air. Radiation dose for workers and public was estimated from these levels of radon. The data showed that the thermal processes can control the behavior of radon which can be also influenced by various physical and chemical parameters such as pH and redox potential.

A Study of the Impact of Industrial Fluoride Emissions on a Rural Environment

In this note we study current fluoride levels in the area of Onton, Cantabria (Spain), in the vicinity of a factory whose main industrial activity is the production of fluoride compounds. When the factory opened in the early 1970s, it was the source of a serious pollution problem; an increasing number of cases of fluorosis in cattle on farms near the factor were detected in addition to extensive damage to vegetation. Although the company implemented an antipollution plan to minimize fluoride emission levels in 1975, this problem has not yet been solved. The factory is situated by the sea on the north coast of Spain in a mountainous area. Two valleys stretch south and southeast of the factory in the direction of the prevailing winds. The climate is mild and wet. Since stock-raising is the dominant activity in the region, the area is mostly devoted to pasture. The study, which was done in 1986, measured fluoride concentrations in air, surface water, and pastures, and in milk and urine samples from cattle.

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.

pH of rainfall in the city of Santander (Spain)

Abstract Values of the pH in rainfalls along the 1983 year at the city of Santander, Spain, are shown. A simple study about the correlation of the pH values with the SO2 levels in air and some meteorological variables is carried out.