Contribution to total indoor radon exposure from Thoron ({sup 220}Rn) decay progeny in three buildings in Springfield, Missouri
- Southwest Missouri State Univ., Springfield, MO (United States)
Increasing evidence that thoron ({sup 220}Rn) and its progeny contribute significantly to the health risk from indoor radon has intensified research efforts to assess the hazards of thoron relative to ordinary radon ({sup 222}Rn) and to determine the sources of indoor thoron. In the study reported here, potential alpha energy concentrations (PAEC) for thoron ({sup 220}Rn) and radon ({sup 222}Rn) were measured by grab sampling over periods of several months in three buildings under various conditions (building open, dosed, heated, air conditioned). In two houses the temporal behavior of outdoor/indoor thoron progeny was found to be highly correlated with that of outdoor/indoor radon progeny, suggesting that all derive from a common source, presumably soil. In these houses contributions to total PAEC from thoron progeny were significantly greater in indoor air than in the outdoor air. Indoors, the PAEC ratio ({sup 220}Rn:{sup 222}Rn) ranged from 0.38 to 1.66 and was, on average, 2-4 times as great as the concurrent ratio for outdoor air. The annual effective dose equivalent from thoron progeny in these buildings is estimated to be 27-29% as large as that from radon progeny. In a four-story office building no significant differences were observed between activities of outdoor and indoor thoron progeny. These data suggest that in this case continuous intake of outside air through the heating/cooling system is the major source of indoor thoron progeny.
- OSTI ID:
- 273850
- Journal Information:
- Radioactivity and Radiochemistry, Journal Name: Radioactivity and Radiochemistry Journal Issue: 3 Vol. 3; ISSN RARAE6; ISSN 1045-845X
- Country of Publication:
- United States
- Language:
- English
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