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The Concept of Equivalent Radon Concentration for Practical Consideration of Indoor Exposure to Thoron
Radiation Protection Bureau, Health Canada, 2720 Riverside Drive, Ottawa K1A 0K9, Canada
* Author to whom correspondence should be addressed.
Received: 14 December 2011; in revised form: 6 January 2012 / Accepted: 16 January 2012 / Published: 18 January 2012
Abstract: To consider the total exposure to indoor radon and thoron, a concept of equivalent radon concentration for thoron is introduced, defined as the radon concentration that delivers the same annual effective dose as that resulting from the thoron concentration. The total indoor exposure to radon and thoron is then the sum of the radon concentration and the equivalent radon concentration for thoron. The total exposure should be compared to the radon guideline value, and if it exceeds the guideline value, appropriate remedial action is required. With this concept, a separate guideline for indoor thoron exposure is not necessary. For homes already tested for radon with radon detectors, Health Canada’s recommendation of a 3-month radon test performed during the fall/winter heating season not only ensures a conservative estimate of the annual average radon concentration but also covers well any potentially missing contribution from thoron exposure. In addition, because the thoron concentration is much lower than the radon concentration in most homes in Canada, there is no real need to re-test homes for thoron.
Keywords: radon-220; thoron; radon-222; radon; indoor exposure
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Chen, J.; Moir, D. The Concept of Equivalent Radon Concentration for Practical Consideration of Indoor Exposure to Thoron. Int. J. Environ. Res. Public Health 2012, 9, 286-293.
Chen J, Moir D. The Concept of Equivalent Radon Concentration for Practical Consideration of Indoor Exposure to Thoron. International Journal of Environmental Research and Public Health. 2012; 9(1):286-293.
Chen, Jing; Moir, Deborah. 2012. "The Concept of Equivalent Radon Concentration for Practical Consideration of Indoor Exposure to Thoron." Int. J. Environ. Res. Public Health 9, no. 1: 286-293.