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



Ilia and Bill



Thoron in air is harder to measure than Radon in air, but I would guess that

the reverse is true for the progeny. A good (but old) reference is the 1985

NEA Group of Experts report "Metrology and Monitoring of Radon, Thoron and

their Daughter Products". OECD, 1985.I haven't reviewed this report

recently.



My expertise is in vivo monitoring, dosimetry and risk, not air monitoring,

and some related publications are



DOSIMETRY ASPECTS OF EXPOSURE TO RADON AND THORON DAUGHTER PRODUCTS

 Report by a Group of Experts of the Organization for Economic Co-Operation

and  Development Nuclear Energy Agency (1983).



A MODEL TO DESCRIBE THORON EXHALATION FOLLOWING AN INHALATION EXPOSURE TO

THORIA POWDERS

 J.R. Johnson and B.F. Peterman

 Published in the Conference Proceedings of the Workshop on Lung Modelling

for Inhalation of Radioactive Materials, Oxford, UK, 1984 March.  Published

in "Lung Modelling for Inhalation of Radioactive Materials", EUR Report

9384, Commission of the European Communities, Luxembourg (1984) 193-196.



THE RELATIVE EFFECT OF VENTILATION ON THE POTENTIAL ALPHA ENERGY FROM RADON

AND THORON DAUGHTERS

 J.R. Johnson

 AECL-8823, Health Physics 49 No. 5 (1985) 996-998.





John R Johnson

____________

4535 West 9th Ave.

Vancouver, B. C.

V6R 2E2

(604) 222-9840

idias@interchange.ubc.ca





----- 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 12:01 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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