The Transfer of Radon From Domestic Water to Indoor Air

Abstract

Theoretical and experimental literature dealing with the release of radon from water to air is reviewed and synthesized. Primary emphasis is placed on releases from domestic water supplies to indoor air within the context of a general indoor radon problem. The widely used assumption of 1 pCi/L increment in indoor air per 10 000 pCi/L in the water supply is valid, but regional and individual variations are important.

Evaluation of radon occurrence in groundwater from 16 geologic units in Pennsylvania, 1986–2015, with application to potential radon exposure from groundwater and indoor air

“…7). Groundwater within the Peters Creek Schist (Xpc) has a radon concentration range of 1,743 to 9,135 pCi/L, which corresponds to estimated contributions to indoor air of 0.2 to 0.9 pCi/L, based on exchange ratios of 10,000:1 for water:air developed by Prichard (1987). Although the magnitude of these contributions from the groundwater is relatively low, 81 percent (table 4) of the population living on the Peters Creek Schist outcrop relies on groundwater supplied by domestic self-supply wells.…”

“…The limits proposed by the EPA do not apply to drinking water obtained from domestic self-supply wells, and the relative contribution of radon from groundwater to indoor air is not known, although each 10,000 pCi/L in water has been estimated to increase indoor air concentrations by 1 pCi/L and thus increase health risks (Milry and Cothern, 1990;Prichard, 1987). The 10,000:1 water:air radon ratio varies considerably from house to house and is a general national average (National Research Council, 1999).…”

Development and calibration of a portable radon sampling system for groundwater 222Rn activity concentration measurements

“…One of the main agents of this exposition is 222 Rn, especially if concentrated in poorly aerated dwellings. While most of the radon present in indoor environments is originated in the soil, the use of groundwater can represent, depending of local conditions, a significant mechanism of radon transfer to indoor air (Gessel and Prichard, 1978;Cothern et al, 1986;Prichard, 1987;Lawrence et al, 1992;Folger et al, 1994).…”

Waterborne radon pollution of indoor air

“…Several studies, starting with reports of Kahlos and Asikainen (1980), have suggested that radon dissolved in the home water supply can substantially contribute to the indoor radon of the home. Several subsequent studies have estimated that a water supply with a radon concentration of 10,000 pCi/L would add about 1 pCi/L to the indoor radon due to the outgassing of the domestic water supply (Cothern, 1987;Prichard, 1987). Three booklets published by the EPA (US-EPA 1987a, 1987b, 1987c state that radon-enriched domestic water must have about 10,000 pCi/L of radon to contribute 1 pCi/L to indoor radon (a 10,000:1 ratio).…”