Soil gas measurements below foundation depth improve indoor radon prediction

• Published in: Science of the total environment 2001-05, Vol.272 (1), p.337-341
• Main Authors: Johner, H.U., Surbeck, H.
• Format: Article
• Language: English
• Subjects: Applied sciences; Atmospheric pollution; Biological and physicochemical properties of pollutants. Interaction in the soil; Buildings. Public works; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; Indoor pollution and occupational exposure; Mitigation; Permeability; Pollution; Pollution indoor buildings; Pollution, environment geology; Radon; Radon availability index; Soil and sediments pollution; Soil gas; Top layer
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/S0048-9697(01)00712-4

A soil gas measurement method developed earlier, [Nucl Tracks Radiat Meas, 22(1–4) (1993) 468] was applied to boreholes drilled to below foundation depth. Radon concentration and permeability were measured at 50-cm intervals. In radon prone areas, permeability showed an increase with depth over several orders of magnitude, indicating a low permeability top layer with a thickness of 0.5 m and more. A radon availability index (RAI) was empirically defined and the maximum RAI of each boring proved to be a reliable indicator for radon problems in nearby houses. The permeability of the top layer also proved to be an important factor for a better understanding of soil gas transport and the influence of rain. Implications for radon mitigation are derived.