Application of airborne radiometric surveys for large-scale geogenic radon potential classification

  • Javier Elío Centre for the Environment, Trinity College, Dublin, Ireland; Department of Planning, Aalborg University Copenhagen, Copenhagen, Denmark
  • Quentin Crowley Centre for the Environment, Trinity College, Dublin, Ireland
  • Ray Scanlon Geological Survey, Dublin, Ireland
  • Jim Hodgson Geological Survey, Dublin, Ireland
  • Stephanie Long Environmental Protection Agency of Ireland, Dublin, Ireland
  • Mark Cooper Geological Survey of Northern Ireland, Belfast, Northern Ireland
  • Vincent Gallagher Geological Survey, Dublin, Ireland
Keywords: radon mapping, radon potential, gamma-ray spectrometry, uranium, soil-gas


Background: Indoor radon represents an important health issue to the general population. Therefore, accurate radon risk maps help public authorities to prioritise areas where mitigation actions should be implemented. As the main source of indoor radon is the soil where the building is constructed, maps derived from geogenic factors ([e.g. geogenic radon potential [GRP]) are viewed as valuable tools for radon mapping.

Objectives: A novel indirect method for estimating the GRP at national/regional level is presented and evaluated in this article.

Design: We calculate the radon risk solely based on the radon concentration in the soil and on the subsoil permeability. The soil gas radon concentration was estimated using airborne gamma-ray spectrometry (i.e. equivalent uranium [eU]), assuming a secular equilibrium between eU and radium (226Ra). The subsoil permeability was estimated based on groundwater subsoil permeability and superficial geology (i.e. quaternary geology) by assigning a permeability category to each soil type (i.e. low, moderate or high). Soil gas predictions were compared with in situ radon measurements for representative areas, and the resulting GRP map was validated with independent indoor radon data.

Results: There was good agreement between soil gas radon predictions and in situ measurements, and the resultant GRP map identifies potential radon risk areas. Our model shows that the probability of having an indoor radon concentration higher than the Irish reference level (200 Bq m-3) increases from c. 6% (5.2% – 7.1%) for an area classified as Low risk, to c. 9.7% (9.1% – 10.5%) for Moderate-Low risk areas, c. 14% (13.4% – 15.3%) for Moderate-High risk areas and c. 26% (24.5% – 28.6%) for High risk areas.

Conclusions: The method proposed here is a potential alternative approach for radon mapping when airborne radiometric data (i.e. eU) are available.


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