european atlas of natural radiation including harmonized radon maps of the European Union
|Location||International Geological Congress,oslo 2008|
|Author||De Cort, Marc; Dubois, Gregoire; Bossew, Peter; Tollefsen, Tore|
|Holding Date||07 October 2008|
Subsequent to publishing the European atlas of 137Cs deposition after the Chernobyl accident, the European Commission (EC) has started to explore the possibility of preparing a European atlas of natural radiation. Such an atlas would help to familiarize the public with its environment as naturally radioactive and to highlight regions with elevated levels of natural radiation, and to provide a database for further studies. By far, radon is known to be the main contributor to exposure from natural background radiation. Because this radioactive gas is also considered to be the leading cause of lung cancer second only to smoking, most European countries have adopted a number of regulations to identify radon-prone areas. However, a comparison of these surveys has shown that a very large variety of methods are being used to measure and report radon levels. As a result, collecting information on radon data and integrating them on a single platform poses a number of serious conceptual and technical challenges. Most frequently, measurements have been made directly in dwellings to assess direct exposure of the population. These observations often show very strong spatial variability over short distances and, as a result, interpolation for mapping purposes remains a difficult task. Moreover, given the strong impact of the type of construction and of the living habits on the radon concentrations, maps of indoor radon levels are not the best means to visualize the geographical distribution of the natural source term of the radon gas. Still, because indoor radon measurements are available in most European countries, most National Authorities have agreed to collaborate on preparing a European map of indoor radon levels using a reference grid with resolution 10x10 km. More precisely, local statistics of annual estimates and/or measurements made on ground floors will be used to fill the grid as this information was found to be the smallest common denominator between countries. Using a European reference grid has the additional advantages that data processing and maintenance are greatly simplified and that National Authorities do not reveal any information on the exact locations of the measurements, an issue that could trigger administrative difficulties because of obvious privacy reasons.
Another approach currently explored is the possibility to prepare a European map of the geogenic radon potential. In contrast to the indoor approach, soil-gas measurements and geological data are required. This would lead us to a map that would be closer to the original scope of the atlas as the natural origin of radon would be better highlighted. However, preparing such a map on the basis of a few heterogeneous data is an even more challenging task considering that there is not yet a clear definition of exactly what variable should be mapped in a geogenic radon map.
This presentation aims to present the current status of this project and to highlight forthcoming challenges.