[ RadSafe ] FW: Reporter's question about lower limits ofdetection

Steven Dapra sjd at swcp.com
Sun Aug 7 21:11:56 CDT 2011

Aug. 7

         This depends on how one chooses to define the word 
"trivial."  Who measured the levels of radiation, where they were 
measured, distance driven after exposure, etc., etc., are irrelevant 
and immaterial.

         Where is your "laboratory," Chris, and what kind of 
instruments are (presumably) you using to conduct these 
measurements?  Describe your methods of testing, including your controls.

Steven Dapra

At 06:39 AM 8/7/2011, you wrote:

>Dear Radsafers,
>It was my intention to show that the levels in Japan in air were not 
>trivial. I do know this because I have measured it in several car 
>filters for which the engine size is known and the number of km 
>driven after the incident is known. The efficiency of the filters is 
>assumed to be 50% but this is not known for sure although I have 
>asked the manufacturers. The filters showed between 1.2 and 3Bq per 
>cu metre of Cs-137. This can be compared with the attached data from 
>Harwell. The results were from my lab and also from Harwell who we 
>paid to do the analysis.
>I am interested to learn that the levels were higher in the USA 
>during the atmospheric tests than in the UK: Stewart Farber says 
>100mBq/m3. Probably because the US is where many of the tests were done.
>But my argument was about Japan, not levels in the USA. I am quite 
>aware that the levels in the USA were far smaller, as we would 
>expect. But i see a maximum of 0.116pCi is 4.29mBq/m3 The average is 
>0.7mBq/m3. Compare with the graph attached. But I think it depends 
>on where you live, doesnt it? And what other stuff comes along as a passenger.


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