Multiparametric analysis for the determination of radon potential areas in buildings on different soils of volcanic origin.

The transposition of the European EURATOM directive into the regulations of the different member states of the European Union involved governments making great efforts to define priority action maps against indoor radon exposure in buildings over a short time period. In Spain, the Technical Building Code established 300 Bq/m as a reference level and set up a classification of municipalities in which remediation measures should be adopted for radon exposure in buildings. Oceanic volcanic islands, such as the Canary Islands, present high geological heterogeneity in a small space due to their volcanic origin. This variability poses a challenge to the elaboration of radiological risk maps, which makes it necessary to have a high density of data to collect local variations. This paper presents a methodology to obtain accurate radon risk maps based on geological criteria and terrestrial gamma radiation. The predictive efficiency of these maps is statistically verified using indoor radon concentration data measured in buildings. Other radiological variables, which are commonly used as criteria for radon risk prediction found in the literature, were also applied, such as the geogenic radon potential and the activity concentration of natural radioisotopes in soils. The higher resolution of the maps obtained allows for a more detailed classification of radon risk zones in the study area than the current risk maps published in the Spanish building regulations.