ABSTRACT
Indoor radon concentrations were measured in different seasons in 104 dwellings located on a highly permeable ice-marginal moraine in Kinsarvik, Western Norway. The measurements revealed the highest indoor radon levels ever detected in Norway and extreme variations in seasonal and short-term indoor radon levels. Annual average indoor radon concentrations up to 56 000 Bq m(-3) and a mean value of 4340 Bq m(-3) for the whole residential area are reported. By using the ICRP conversion factors to effective dose, these indoor radon values correspond to a total annual effective dose of 930 mSv and 72 mSv, respectively. By using the conversion as recommended by UNSCEAR, the effective doses would be about 50% higher. The indoor radon concentrations are found to be strongly influenced by thermally induced flows of radon-bearing soil air directed towards the upper part of the ice-marginal deposit in winter and towards the area of lowest elevation in summer. The pattern of seasonal variations observed suggests that in areas where thermal convection may occur, annual average indoor radon levels should be derived from measurements performed both in summer and in winter.
Subject(s)
Air Pollution, Indoor/analysis , Air Pollution, Radioactive/analysis , Geologic Sediments , Housing/statistics & numerical data , Radiation Monitoring/methods , Radon/analysis , Air Pollution, Indoor/statistics & numerical data , Air Pollution, Radioactive/statistics & numerical data , Ice Cover , Norway , Permeability , Radiation Monitoring/statistics & numerical data , SeasonsABSTRACT
Results of indoor gamma radiation and radon measurements in 95 wooden dwellings located in a Norwegian thorium-rich carbonatite area using thermoluminescent dosemeters and CR-39 alpha track detectors, respectively, are reported together with a thorough analysis of the indoor data with regard to geological factors. Slightly enhanced radium levels and thorium concentrations of several thousands Bq kg(-1) in the carbonatites were found to cause elevated indoor radon-222 levels and the highest indoor gamma dose rates ever reported from wooden houses in Norway. An arithmetic mean indoor gamma dose rate of 200 nGy h(-1) and a maximum of 620 nGy h(-1) were obtained for the group of dwellings located directly on the most thorium-rich bedrock.
Subject(s)
Air Pollutants, Radioactive/analysis , Air Pollution, Indoor/analysis , Radon/analysis , Gamma Rays , Geologic Sediments/chemistry , Norway , Radiation Monitoring , Radium/analysis , Thermoluminescent Dosimetry , Thorium/analysisABSTRACT
Indoor radon levels in 1618 Norwegian dwellings located in different geological settings are compared with geological information. The results show a significant correlation between indoor radon levels and geological factors. Radium content and permeability of the building ground have been found to be useful indicators of indoor radon concentrations. Based on easily accessible geological data, an assessment of the radon potential of an area can be given. Areas of high radon risk in Norway include: (a) exposed bedrock with elevated levels of radium; and (b) highly permeable unconsolidated sediments derived from all rock types and moderately permeable sediments derived from rock types rich in radium. A comparison of indoor radon with house construction characteristics and ventilation habits suggests that radon concentrations in Norwegian dwellings are also influenced by ventilation system, aeration habits and floor level of the room where the measurements were carried out. The significant correlation between indoor radon levels and geological factors observed in the present investigation indicates that it is possible to outline areas of high radon risk in Norway based on geological information.
