Using geogenic radon potential to assess designation of radon priority areas in Ireland

Abstract

<p>Radon is a radioactive gas which emanates from rock, soil and water. Radon concentrations in the<br>atmosphere are generally very low (typically <5 Bq m-3), however it can occur at much higher levels<br>in soil (typically 10’s-100’s kBq m-3), or enclosed spaces such as buildings and caves (typically 10’s-<br>100’s Bq m-3). Exposure to radon and its daughter products is associated with an elevated risk of<br>developing lung cancer. Ireland has a population weighted indoor radon concentration of 98 Bq m-3<br>resulting in an estimated 300 annual lung cancer cases per year, representing approximately 12% of<br>the annual lung cancer cases. A national-scale legislative radon-risk map has a 10 x 10 km spatial<br>resolution and is based exclusively on indoor radon measurements (i.e. it does not contain any<br>geological information). The legislative map satisfies the European Council Directive<br>2013/59/EURATOM Basic Safety Standard, in that it defines “high radon” areas as those where >10%<br>of homes are estimated to exceed the national reference level of 200 Bq m-3. New buildings in such<br>areas are legally required to have a barrier, with low radon permeability installed.</p><p>This research focuses on a karstic region of SE Ireland, which features some exceptionally high<br>indoor radon concentrations (65,000 Bq m-3), even though it is not classified as a “high radon” area<br>on the national legislative map. Here we demonstrate the use of measuring sub-soil radon<br>concentrations and sub-soil permeability, in order to construct a radon potential (RP) map of the<br>area. Extremely high sub-soil radon concentrations (>1443 kBqm-3) and radon potential values<br>(>200) are spatially associated with Namurian shales, interbedded with limestone. Overall, we<br>classify the study area as high radon potential (RP >35) using this technique. We suggest all areas<br>underlain by Namurian shales in Ireland should undergo similar radon potential mapping, and if<br>necessary, should be re-designated as “high radon” areas. If deemed appropriate (i.e. where RP<br>>35), such a designation will help to protect the general public from the harmful effects of indoor<br>radon exposure, and will help to lower the incidence of radon-related lung cancer in these areas.</p>