[ RadSafe ] Hot particles on automobile air filters

Fri Jun 24 14:19:05 CDT 2011

-----Original Message-----
From: radsafe-bounces at agni.phys.iit.edu on behalf of radbloom at comcast.net
Sent: Fri 24/06/2011 16:14
To: The International Radiation Protection (Health Physics) Mailing List
Cc: The International Radiation Protection (Health Physics) Mailing List
Subject: Re: [ RadSafe ] Hot particles on automobile air filters

I'm curious about the retention efficiency of iodine vs cesium on these filters.  I know the chemical form of the iodine would affect its collection efficiency, but typically carbon filters, not particulate filters, are used to (most efficiently) collect iodine species.  Also, it's noted that the filters have been in transit for a long time - is that long compared to I-131's 8-day half-life, or just long compared to the radon progenies' half-lives? 

Cindy Bloom  

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

From: "Chris Busby" <C.Busby at ulster.ac.uk> 
To: "The International Radiation Protection (Health Physics) Mailing List" <radsafe at agni.phys.iit.edu>, "The International Radiation Protection (Health Physics) Mailing List" <radsafe at agni.phys.iit.edu>, "The International Radiation Protection (Health Physics) MailingList" <radsafe at agni.phys.iit.edu> 
Sent: Friday, June 24, 2011 9:08:16 AM 
Subject: Re: [ RadSafe ] Hot particles on automobile air filters 

-----Original Message----- 
From: radsafe-bounces at agni.phys.iit.edu on behalf of kmcheng1 at netvigator.com 
Sent: Thu 23/06/2011 22:29 
To: The International Radiation Protection (Health Physics) Mailing        List; The International Radiation Protection (Health Physics)        MailingList 
Subject: Re: [ RadSafe ] Hot particles on automobile air filters 

A simple demonstration we used to show to junior school students about natural radioactivity was to cover the nozzle of a vacuum cleaner with a filter paper, turn on the cleaner for 5 to 10 minutes and then put the filter paper in front of a GM counter.  There were normally sufficient radon progeny on the filter paper to give a significant count rate above the background.  The same would be expected on an automobile air filter shortly after it is taken out of a running engine. 

That is probably nothing new, unless the gamma spectrum shows that there are something else other than radon progeny. 

Clement Cheng 
Radiation Health Unit 
Department of Health 
Hong Kong SAR, China 

> 
> ???: "Brennan, Mike  (DOH)" <Mike.Brennan at DOH.WA.GOV> 
> ??: 2011/06/24 ??? ?? 03:29:24 HKT 
> ???: "The International Radiation Protection (Health Physics) MailingList" 
>         <radsafe at agni.phys.iit.edu> 
> ??: Re: [ RadSafe ] Hot particles on automobile air filters 
> 
> Ah, so the data is robust enough to share with friends, so they can 
> spread the news worldwide, but not robust enough to expose to 
> potentially critical examination.   
> 
> How very, very, usual. 
> 
> >Sorry, Its not my data and you will have to wait for it to be 
> published. It was meaursed in the USA by a colleague. I do however have 
> my own data and will share it with you in due course. 
> Sincerely 
> Chris 
> 
> Sinecerly 
> Chris 
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But these filters have been across the Pacific and in the mail system for a long time. The gamma spectrum of the filters shows Cs137 and I131. What you say is that the particles in the filters are hot (register as splashes on Xray film) becasue of radon daughters? yes? 
Chris 
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I agree
But there was a lot more Iodine than Cs to begin with; we saw the same effect in Europe
C