Re: Re[2]: Rn, Epidemiology + thoron

["R. William Field" <bill-field@UIOWA.EDU>]

Ilia,



Yes, I was speaking just of the movement of the thoron that has quite a

variance in concentration just over one room.  The thoron daughters would

have more mobility once generated, but certainly a shorter biological

half-life once breathed in.  Nonetheless, I do agree it may not be an

insignificant contribution to dose.



I will contact you directly and we can discuss the passive monitoring.



Regards, Bill





----- Original Message -----

From: Yarmoshenko IV <ivylist@ecko.uran.ru>

To: R. William Field <bill-field@uiowa.edu>

Cc: RADSAFE <radsafe@list.vanderbilt.edu>

Sent: Saturday, February 16, 2002 2:01 AM

Subject: Re[2]: Rn, Epidemiology + thoron





> Bill,

> Some clarifications on thoron.

> Half  life  of  Pb-212  (thoron  daughter)  is about 10 h consequently

> thoron  progeny  is  equally  distributed within the room. Due to high

> variability   of   thoron   equilibrium  factor  indoor,  thoron  gas

> concentration  measurement  does not surrogate thoron progeny exposure

> assessment (as in the radon case). Unfortunately I'm not familiar with

> any  integral  passive technique of thoron progeny measurements and as

> far  as  I understand the retrospective measurements of thoron progeny

> is  impossible (am I right?). We used the grab sampling techniques for

> surveys  in  Ural  region  of  Russia, by which results thoron progeny

> contributes  from  5  to  30  %  to  total  average Rn+Tn exposures by

> settlements.

>

> Regards,

> Ilia

>

> Ilia Yarmoshenko

> Radiation Laboratory

> Institute of Industrial Ecology

> Ekaterinburg

> Russia

>

>

> RWF> Regarding thoron, because of its short half life, the distance it

travels is

> RWF> much less.  But, if you are sleeping right next to a source, you can

get a

> RWF> significant exposure.  The glass based detector we used in Iowa has

> RWF> specificity for thoron so we do plan to look at that down the road as

we

> RWF> clear some other hurdles.  We do have those measurements already

performed.

> RWF> One interesting note is that outdoor thoron exposure may be greater

than we

> RWF> thought.

>



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