Variation of Radon Sources and Indoor Radon along the Southwestern Edge of the Canadian Shield

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Health and Medical Physics | Physics


Radon source and indoor radon concentrations were measured in 240 homes. Waterborne radon concentrations ranged from 0.4 to 360 kBq/m3, with a geometric mean value of 8.6 kBq/m3 (230 pCi/L). Dry soil samples showed an average radon emanation of 16 Bq/kg (0.43 pCi/g) and an average radium content of 26 Bq/kg (0.7 pCi/g). In situ, surface soilborne 214Bi concentrations ranged from 5 to 50 Bq/kg. Yearly average, indoor airborne radon concentrations ranged from 7 to 3800 Bq/m3 (0.2 to 103 pCi/L) and varied significantly by season and by compartment. Radon concentrations in living spaces ranged from 7 to 2100 Bq/m3, with an average value of 130 Bq/m3 (3.6 pCi/L) and a geometric mean of 100 Bq/m3 (2.7 pCi/L). Source and airborne radon concentrations are best described by log-normal distributions. Localized clusters of houses showed significant variation in source and airborne radon, concentrations. Regional and geological clusters showed no significant variation in airborne radon, but did evidence some significant variation in source concentrations. Linear regression analysis of airborne radon in below-ground compartments and radon sources indicated significant correlation for emanative radon at individual sites, local clusters, and regional clusters and for 214Bi concentrations in local clusters.