Pb-210 on air filters

[brian.keele@swec.com]

Does anybody have any information relating to the amount of Pb-210, or other
natural ambient isotopes, that could realistically accumulate on an air filter
in
an outdoor environment and present an interference in a gross alpha measurement?
The filters are held for 14 days before a gross alpha counting to allow short
half-life radon/thoron daughters to decay.  We have a thorium site.  I suspect a
large proportion of the observed counts from our perimeter stations may be from
Pb-210.

Thank-you,
Brian Keele


************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html