Assessment of Intake, Exposure, and Dose from Radon, Thoron, and Their Progeny

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DOE-STD-1121-98
where
denotes the concentration of 218Po in pCi/L;
CPo-218
denotes the concentration of 214Pb in pCi/L; and
CPb-214
denotes the concentration of 214Bi in pCi/L.
CBi-214
PAEC can be computed from concentration measurements of the short-lived thoron progeny in air
(UNSCEAR 1993):
(29)
where
denotes the concentration of 212Po in pCi/L; and
CPb-212
denotes the concentration of 212Bi in pCi/L.
CBi-212
Another acceptable method for workplace monitoring of exposure to radon progeny is to measure
222
the  Rn itself, and convert it to PAEC using known equilibrium factors. DOE's 10 CFR 835 permits
calculating equilibrium equivalent concentration, EEC, from radon concentration measurements, C,
based on knowledge or assumption of an equilibrium factor, F:
(30)
If F has not been measured, it is acceptable under some circumstances to assume a default indoor value of
FRn = 0.4 (UNSCEAR 1988, 1993; ICRP 1993a). If C is in units of :Ci/mL, then EEC will also be in
units of :Ci/mL (note: 1 pCi/L = 10!9 :Ci/mL).
For 222Rn, FRn is defined as
(31)
where
= the concentration of 218Po;
CPo-218
= the concentration of 214Pb;
CPb-214
= the concentration of 214Bi; and
CBi-214
= the concentration of 222Rn.
CRn-222
For 220Rn, FTn is defined as
(32)
where
81

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