Fwd: Radon equilibrium factor

["Thatcher, Drew" <dht0303@hub.doh.wa.gov>]

                  ***** Original Message Follows *****

Can anybody advise on the equilibrium factor to use for outdoor radon?

Radon equilibrium factors for indoor and outdoor air are often quoted as
0.4 and 0.8 respectively.
ICRP65 use 0.4 for indoor air,  but I do not have a good reference for
outdoor air.  Is the equilibrium factor seasonal? How variable is it?

Andries Leuschner
andries.leuschner@pixie.co.za

NCRP 94 recommends 0.7.  NCRP 78 provides some good information on 
daughter disequilibrium and also recommends the use of 1/0.9/0.7/0.7 for 
outdoors (Rn-222, Po-218, Pb-214, Bi-214).  NCRP 78 estimates the range 
of disequilibrium to be about 20% of normal environmental situations.  I 
could not locate any information on seasonal variation of the equilibrium 
factor.

Regards/  Drew Thatcher