Comparison of radon mapping methods for the delineation of radon priority areas – an exercise

Abstract

Background: Many different methods are applied for radon mapping depending on the purpose of the map and the data that are available. In addition, the definitions of radon priority areas (RPA) in EU Member States, as requested in the new European EURATOM BSS (1), are diverse.
 Objective: 1) Comparison of methods for mapping geogenic and indoor radon, 2) the possible transferability of a mapping method developed in one region to other regions and 3) the evaluation of the impact of different mapping methods on the delineation of RPAs.
 Design: Different mapping methods and several RPA definitions were applied to the same data sets from six municipalities in Austria and Cantabria, Spain.
 Results: Some mapping methods revealed a satisfying degree of agreement, but relevant differences were also observed. The chosen threshold for RPA classification has a major impact, depending on the level of radon concentration in the area. The resulting maps were compared regarding the spatial estimates and the delineation of RPAs.
 Conclusions: Not every mapping method is suitable for every available data set. Data robustness and harmonisation are the main requirements, especially if the used data set is not designed for a specific technique. Different mapping methods often deliver similar results in RPA classification. The definition of thresholds for the classification and delineation of RPAs is a guidance factor in the mapping process and is as relevant as harmonising mapping methods depending on the radon levels in the area.

Outdoor Radon as a Tool to Estimate Radon Priority Areas—A Literature Overview

“…The latter could be estimated using different geogenic parameters such as radon in soil gas and soil permeability, radionuclides contents in soil and rocks, and also radon flux and outdoor radon investigated in the present paper. Within the MetroRADON project, mapping exercise was organized aiming to test applicability of different mapping methods, developed in various countries, on the data set in another country and to test to what extent different methods applied on the same set of data can give similar results [ 36 ]. In most of these proficient mapping methods, various types of input parameters were used: (1) measured quantities such as: indoor radon concentrations, radon in soil gas, permeability, radionuclide content in soil, terrestrial gamma dose rate; (2) geological data: type of soil, hydrology and faults; (3) meteorological data: precipitation, pressure; and (4) anthropogenic factors such as building characteristics, living habits (influencing ventilation rate) [ 36 ].…”

Radon Hazard in Central Italy: Comparison among Areas with Different Geogenic Radon Potential

“…The construction of the GRP of an area is based on the analysis of the spatial distribution of some proxy geological information (e.g., lithological types, U, Th and Ra content, the Rn emanation coefficient from rocks, soil/rock permeability, faults, etc.) that can be related to in situ radon production and migration processes [ 10 , 11 , 17 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 ]. The resulting GPR map defines the spatial distribution of radon risk from sub-surface sources; information that can then be used for land-use zoning and strategic indoor radon monitoring purposes.…”

On harmonization of radon maps

“…Data may also be interpolated through geostatistical techniques to estimate values at unsampled locations and create continuous maps. Different methods are plausible for a purpose, but, though in general, they yield different results; this cannot be expected to be a source of major inconsistency in most cases; see also (15). More serious are the following.…”

“…Different mapping methods often deliver the same results in RPA classification, depending on the definition of RPAs. The definition of thresholds is a key factor in delineation of RPAs and for harmonization purposes (15). For a detailed discussion about harmonization of radon mapping and RPA definition, see (9).…”