Mapping potential radon-222 exhalation at the soil surface: an example in Armorica, Brittany
GÉRALDINE IELSCH, MICHEL CUNEY
Environnement, Risques & Santé - Vol. 3, n° 1, janvier-février 2004, pp35-43
Radon-222 is a radioactive natural gas produced by thé decay of radium-226, itself produced by thé decay of uranium-238 naturall y présent in rocks and soil. It can accumulate in buildings, and inhalation of this gas and its decay products is a potential human health risk. Effective risk management needs to déterminé in advance thé areas in which thé density of buildings with high radon levels is likely to be highest. Research programs over thé past several years have successfully developed a methodology for predicting and mapping thé radon exhalation potential at thé soit surface. This approach, based on quantification of thé radon flux at thé surface, starts from a précise characterization of thé main local geological and pedological variables that influencé thé radon source and its transport to thé soillatmosphere interface. The methodology crosses thé cartographie analysis into a Geographic Information System (GIS) and a simplified model for vertical transport of radon by diffusion through pores in thé soit. This code, called TRACHGEO, calculates thé radon flux density as a function of thé chemical and physical properties of thé rock and thé subjacent soil. In this paper, we discuss thé results from thé application of this approach to an area (3,000 km1) located in Brittany (Western France).