Studies of Natural Radioactivity Related to the Soil Geochemical Landscapes Project

Radon is a naturally-occurring hazard and the second leading cause of lung cancer. In 2007 Health Canada lowered the threshold limit of exposure in Canadian homes and buildings above which there is a recommended need for remediation. This change is part of a new radon strategy for Canada and includes new approaches for achieving compliance with the guideline. In 2007 Natural Resources Canada, through the Geological Survey of Canada, entered into a partnership with Health Canada - Radiation Protection Bureau with the end goal of producing a radon map for Canada to guide risk management. A radon map based on geological aspects is a valuable supplement to the radon risk map with indoor radon measurements across Canada, especially for areas where indoor radon measurements are not available or not possible.

The partnership supports new airborne gamma ray spectrometry where there are gaps in the existing coverage and provides for soil gas radon and in-situ gamma ray spectrometry surveys under the auspices of the North American Soil Geochemical Landscapes Project. Variations in soil gas radon concentrations have been used to delineate radon rich areas as have airborne gamma ray spectrometry data along with bedrock and surficial geology information. In 2007, as part of the NASGLP, projects in the Maritime provinces, Ottawa area and Southern Ontario involving in-situ measurements of soil gas radon and gamma ray spectrometry (in particular K, U, Th) were undertaken.

Data from the in-situ surveys will be compared to data from existing regional airborne gamma ray spectrometry surveys and the NASGLP and other geochemical sampling surveys and also the best available information on bedrock and surficial geology. The aim is to develop methodology for identifying areas with high risk potential for radon through the use of these proxy data.