[ RadSafe ] FW: Reporter's questionabout lowerlimits ofdetection

Wed Aug 10 12:45:06 CDT 2011

The comparison was with air at ground level at Chilton near Oxford.
Chris

-----Original Message-----
From: radsafe-bounces at agni.phys.iit.edu on behalf of Kai Kaletsch
Sent: Wed 10/08/2011 16:08
To: The International Radiation Protection (Health Physics) Mailing	List
Subject: Re: [ RadSafe ] FW: Reporter's questionabout	lowerlimits	ofdetection

Chris,

Then I don't understand the comparison to the average atmospheric levels 
that you cite. I would not be surprised that a car's filter sees 1000 times 
more suspended particulate than the atmospheric average. (That's why engines 
have filters. If they were breathing clean air, they wouldn't need filters.) 
Why should I be surprised that rad fallout behaves similarly?

Cheers,
Kai

----- Original Message ----- 
From: "Busby, Chris" <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>
Sent: Wednesday, August 10, 2011 3:59 AM
Subject: Re: [ RadSafe ] FW: Reporter's question about lowerlimits 
ofdetection

> Dear Kai,
> The point of the exercise was to look at what people are inhaling. Not 
> people who stand on the top of a hill.
> Cheers
> Chris
>
>
> -----Original Message-----
> From: radsafe-bounces at agni.phys.iit.edu on behalf of Kai Kaletsch
> Sent: Wed 10/08/2011 06:47
> To: The International Radiation Protection (Health Physics) Mailing List
> Subject: Re: [ RadSafe ] FW: Reporter's question about lowerlimits 
> ofdetection
>
> Stand beside a busy street and take a few deep breaths. After you are done
> coughing up dust, go take a few deep breaths on a quiet hill top. Is it 
> the
> same air? No.
>
> The air near a road is not representative of average atmospheric 
> particulate
> concentration. It is driven by re-suspension.
>
> Cheers,
> Kai
>
>
> ----- Original Message ----- 
> From: "Busby, Chris" <C.Busby at ulster.ac.uk>
> To: "parthasarathy k s" <ksparth at yahoo.co.uk>; "The International 
> Radiation
> Protection (Health Physics) Mailing List" <radsafe at agni.phys.iit.edu>;
> <SAFarber at optonline.net>; "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>
> Sent: Sunday, August 07, 2011 6:39 AM
> Subject: Re: [ RadSafe ] FW: Reporter's question about lower limits
> ofdetection
>
>
>
>
> 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.
>
>
> Cheers
> Chris
>
> Oranges:
>
> The US EPA made excellent measurements of airborne Cs-137 in the US 
> released
> from Fukushima after the accident. Air particulate samples were taken all
> over the USA by the EPA. Based on calibrated Hi-Vo samplers and calibrated
> counting geometry for air filters, the highest levels of Cs-137 in air
> measured were seen in HI, CA, AZ, NV. Cs-137 levels were reported as
> [picoCuries per cubic meter]:
>
> Minimum: 0.000238 pCi/m^3
> Maximum: 0.116
> Average: 0.0189
>
> The above EPA data can be seen at:
> <http://oaspub.epa.gov/enviro/erams_query_v2.simple_output?Llocation=EPA+Reg
> ion&subloc=09&media=AIR-FILTER&radi=Cesium-137&Fromyear=2011&Toyear=2011&uni
> ts=Traditional>
>
>
> Open air testing of 500 nuclear bombs by the US and Soviets, ending in 
> 1963,
> led to many years of significant ongoing nuclear fallout from the mid 
> 1950s,
> reaching a peak level of total terrestrial deposition in 1968. After 1968
> the environmental inventory of Cs-137 and Sr-90 continued to drop steadily
> with minor blips in the US from small nuclear bomb tests by India and 
> China.
> Chernobyl added no more than 1% to the environmental fallout inventory in
> the US.
>
> During the MANY YEARS of nuclear test fallout airborne Cs-137 in 
> essentially
> the entire Northern Hemisphere, including the US, was roughly about 0.1
> pCi/m^3. Peak levels of airborne Cs-137 during the period of open air
> testing were commonly measured at 0.5 pCi/m^3 and higher.
>
> As noted above, the EPA measured a SHORT TERM average of airborne Cs-137 
> in
> the US from Fukushima of 0.0189 pCi/m^3  in those states having the 
> highest
> measured concentrations.
>
> The LONG-TERM average level of airborne Cs-137 in the US during the many
> years of atomic bomb fallout during and for a few years after open air
> testing ended was about 5 times higher than the average SHORT TERM peak
> levels of accurately sampled and measured airborne Cs-137 seen in the US
> from Fukushima [based upon a few measurements fading away to essentially
> nothing after a short time].
>
> Given that what is important in calculating total radiation dose is the
> ratio of the time integrated concentration of airborne exposure to Cs-137 
> in
> this case,  the total exposure of people in the US from open air testing
> fallout is at least 500 times greater than the total exposure from
> short-term peak airborne Cs-137 in the US measured after the Fukushima
> accident [in looking at the areas in the US that had the highest recent
> airborne Cs-137 levels].
>
> And yes, I consider total time-integrated exposure to Fukushima airborne
> Cs-137 and Sr-90 in the US that is about one part in 500  [or less] of the
> time integrated radiation exposure from nuclear bomb test fallout in the 
> US
> to be trivial. -Oranges
>
>
>
> --------------------------------------------------------------------------------
>
>
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