ORIGINAL RESEARCH article
Front. Environ. Sci.
Sec. Toxicology, Pollution and the Environment
Volume 13 - 2025 | doi: 10.3389/fenvs.2025.1599780
This article is part of the Research TopicRadon and Related Health Effects: From Exposure to Risk Assessment and PoliciesView all 9 articles
Outdoor radon and thoron in an area with naturally ventilating bedrock fractures
Provisionally accepted
- 1Norwegian Radiation and Nuclear Safety Authority, Østerås, Norway
- 2Department of Environmental Sciences, Faculty of Engineering and Science, Western Norway University of Applied Sciences, Sogndal, Sogn og Fjordane, Norway
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Open fractures lead to increased permeability of the bedrock, and, if connected to the surface, allow for groundwater flow and air ventilation. Radon and thoron received by groundwater and ventilating air from bedrock can then be released at the surface. We assessed outdoor levels of radon, thoron and their progeny within the area of Stampa, a rock slope instability in western Norway, characterised by open bedrock fractures and subsurface fracture networks. We used alpha track detectors and in-situ measurements, finding outdoor radon levels of up to 2500 Bq m-3 compared to the global averages of 10 Bq m-3. Outdoor radon values had a median of 70 Bq m-3 and a mean of 230-280 Bq m-3, which is higher than the maximum recommended indoor radon level of 200 Bq m-3 in Norway. We identified natural ventilation through open fractures as one important source of these enhanced outdoor levels, and another to be transport by groundwater and release at natural groundwater springs. Natural chimney ventilation changes flow direction between warm and cold seasons, and we identified different levels of radon and thoron between different types of fractures suggesting different ventilation intensities and possibly different sizes of subsurface fracture networks.
Keywords: Radon, Thoron, Ventilation, Bedrock fracture, Geology, Exhalation, Outdoor levels
Received: 03 Apr 2025; Accepted: 13 Jun 2025.
Copyright: © 2025 Haanes, Schreiber, Snook and Maschler. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Hallvard Haanes, Norwegian Radiation and Nuclear Safety Authority, Østerås, Norway
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