Indoor radon mapping and its relation to geology in Hungary

Abstract

Indoor radon mapping may show stronger dependence on geological formations if the measured homes are one-storied houses with no basement. In Hungary, 17,244 homes were investigated on the yearly average of indoor radon concentrations; among these homes, there were 6,154, one-storied, no-basement houses. In Hungary, 21 geological units were created relevant for indoor radon index characterized by lithology, the position of the ground water table, and the gas permeability. Maps were drawn of different topography (counties, grid, geological units) and different values (maximum, mean, indoor radon indexes). A kind of standardization of houses was that only the one-storied, no-basement ones were chosen, but from geological point of view some more information was gained when the wall materials (bricks or adobe) were also taken into account. (“Adobe” is made of clay and straw in Hungary, and not burned as brick, just dried on sunshine). Enhanced indoor radon values can be observed on the bedrock of Cenozoic volcanic rocks and their eroded materials deposited on the local alluvial valleys. Another group with relatively increased indoor radon values can be connected to granite bodies. The grid method is useful for covering large state or even continental areas. For practical public use and detailed radon risk mapping geological or administrative unit-systems could yield more reasonable and useful results.