Time-averaged exposures to 220Rn and 222Rn progeny in Colorado homes.
Week-long time-averaged exposures to naturally occurring 220Rn and 222Rn progeny have been measured at several locations in Colorado by monitoring the alpha activity collected continuously on a fixed-membrane filter. The alpha-energy spectrum associated with the activity collected on the filter was recorded every 15 min using a microcomputer-controlled alpha spectrometer. The alpha counts observed in three energy regions permitted complete separation of the contributions from each decay chain, and calculation of the separate time-averaged potential alpha-energy concentrations in air from 220Rn progeny, PAEC(Tn), and from 222Rn progeny, PAEC(Rn). The time-averaged PAEC(Tn) ranged from 0.3 to 6.9 mWL at 12 indoor locations, and the time-averaged PAEC(Rn) ranged from 1.0 to 59.0 mWL. The ratios of the indoor PAEC(Tn) to indoor PAEC(Rn) ranged from 0.09 to 0.58, with an overall average ratio of 0.32 and a standard deviation of 0.15. The 10 L min-1 flow rate through the filter was selected to approximate the air intake rate of a resting human; the time-averaged PAEC thus represents the progeny concentrations that would have been inhaled by a person breathing the same atmosphere.
Martz
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DE
U.S. Department of Energy, Grand Junction Projects Office, UNC Geotech, CO 81502.
Falco
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RJ
Langner
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GH
D000398:Air Pollution, Radioactive; D000512:Alpha Particles; D001729:Bismuth; D003120:Colorado; D004781:Environmental Exposure; D006798:Housing; D006801:Humans; D007854:Lead; D011059:Polonium; D011886:Radon; D017687:Radon Daughters; D013997:Time Factors
D017687:Radon Daughters; D007854:Lead; D011059:Polonium; D011886:Radon; D001729:Bismuth