In-flight radiation

[ROBBARISH@AOL.COM]

Date: Sat, 13 Nov 2004 12:51:36 -0800

From: "Sandy Perle"  <sandyfl@EARTHLINK.NET>

Subject: Re: Airport screening and  medicine



On 13 Nov 2004 at 12:03, Reuven wrote:



> I once  MEASURED the radiation dose during an intercontinental flight:

> It was  *** 50 times *** HIGHER than the background radiation at sea

>  level.



Reuven,



What did you use to measure the dose described  above, and, what was 

the duration of the flight?



If one considers the  natural background to be, for assumption 

purposes, equals 7 microR/hr, then  you're stating that the rate you 

observed was 350 microR/hr. This does seem  a bit high. I travel quite 

a bit, and, I don't expect that I have observed  the dose rates you 

are quoting. Additional source information would be  appreciated.



-  ----------------------------------------------------------------

Sandy Perle  

Senior Vice President, Technical Operations 

Global Dosimetry Solutions,  Inc. 

2652 McGaw Avenue

Irvine, CA 92614





Sandy and list:

 

Assuming an external background dose (excluding radon) of about 1 mSv  per 

year for a person living at sea level in a coastal city like my own New  York, 

the dose rate per hour is approximately 0.11 microsievert. (0.11 x 24 x  365 = 

1,000 microsievert = 1 mSv)

 

At an altitude of 37,000 feet above New York City the average dose rate in  

2003 was about 5.5 microsievert per hour, about fifty times the sea-level  

background dose. So, respectfully, I believe that the stated claim of a  

measurement on board a commercial aircraft of approximately that dose rate would  be 

correct. But, since about two-thirds of the total dose would come from  

energetic secondary neutrons produced by atmospheric proton interactions, I'd be  

interested in what instrumentation was used by Reuven for his measurement.  

Typically, in-flight measurements by "amateurs" only detect the  low-LET component 

of the cosmic radiation field since those  individuals usually don't have 

neutron detectors. 

 

The assumption by Sandy of a sea-level background dose rate of 7 microR/hr,  

which would imply an annual external background exposure of 60 mR (600 uSv), 

is  not unreasonable. Stating this in SI units as 0.07 microsievert per hour 

one can  then compare the ratio of Sandy's dose rates and mine with the 5.5 

uSv/hr value,  and obtain an increase in the radiation level at altitude of a 

factor  somewhere between 50 (mine) and 80 (his) when compared with sea-level 

doses  here in NY. So, repeating, Reuvens statement about a measured dose rate 50  

times higher than on the ground is not without merit.

 

Considering an aircrew member spending 700 hours per year at that  altitude, 

their annual occupational exposure would be on the order of 3.5  mSv - 4 mSv, 

a value quite consistent with many publications (including  mine) on in-flight 

radiation.

 

Robert Barish, Ph.D., CHP

Author: The Invisible Passenger: Radiation Risks for People Who  Fly

_robbarish@aol.com_ (mailto:robbarish@aol.com)