Relationships between {sup 222}Rn dissolved in ground water supplies and indoor {sup 222}Rn concentrations in some Colorado front range houses
- Geological Survey, Denver, CO (United States)
- Colorado School of Mines, Golden, CO (United States)
- Environmental Protection Agency, Denver, CO (United States)
Indoor {sup 222}Rn concentrations were measured in 37 houses with alpha track detectors placed in water-use rooms near water sources (bathrooms, laundry rooms, and kitchens) and in non-water-use living rooms, dining rooms, and bedrooms away from water sources. Results show that relative contributions of {sup 222}Rn to indoor air from water use are insignificant when soil-gas concentrations are high but become increasingly important as the ratio of {sup 222}Rn-in-water:{sup 222}Rn-in-soil gas increases. High soil-gas {sup 222}Rn concentrations may mask {sup 222}Rn contributions from water even when waterborne {sup 222}Rn concentrations are as high as 750 kBq m{sup {minus}3}. Ground water in Precambrian Pikes Peak granite averages 340 kBq m{sup {minus}3} {sup 222}Rn, vs. 170 kBq m{sup {minus}3} in Precambrian migmatite, but average {sup 222}Rn concentrations in soil gas are also lower in migmatite. Because the ratio of {sup 222}Rn-in-water:{sup 222}Rn-in-soil gas may be consistently higher for houses in migmatite than in Pikes Peak granite, indoor air in houses built on migmatite have a greater relative contribution from water use even though average {sup 222}Rn concentrations in the water are lower. Continuous monitoring of {sup 222}Rn concentrations in air on 15-min intervals also indicates that additions to indoor concentrations from water use are significant and measurable only when soil-gas concentrations are low and concentrations in water are high. When soil-gas concentrations were mitigated to less than 150 Bq m{sup {minus}3} in one house, water contributed 20-40% of the annual indoor {sup 222}Rn concentration in the laundry room ({sup 222}Rn concentration in water of 670 kBq m{sup {minus}3}). Conversely, when the mitigation system is inactive, diurnal fluctuations and other variations in the soil-gas {sup 222}Rn contribution swamp the variability due to water use in the house. 9 refs., 8 figs., 8 tabs.
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AI05-91ER61143
- OSTI ID:
- 54475
- Journal Information:
- Health Physics, Journal Name: Health Physics Journal Issue: 3 Vol. 67; ISSN HLTPAO; ISSN 0017-9078
- Country of Publication:
- United States
- Language:
- English
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