Airline Radiation levels

["H.B. Knowles" <hbknowls@ix.netcom.com>]

>From: "H.B. Knowles" <hbknowls@ix.netcom.com>
>Subject: Re: Airliner Dose Rates

Chris Alston writes, in response to a question by Otto Raabe:
>
>>Date: Wed, 13 May 1998 08:00:00 -0500 (CDT)
>>Reply-To: radsafe@romulus.ehs.uiuc.edu
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>>From: Chris Alston <alstonc@odrge.odr.georgetown.edu>
>>To: Multiple recipients of list <radsafe@romulus.ehs.uiuc.edu>
>>Subject: Re: Airliner Dose Rates
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>>
>>Otto
>>
>>A round trip Seattle - New York City gives you ~7 mrem. At cruising
>>altitudes, 50 - 75% of the DE is from fast neutrons; so partly what's
>>happened to the dose estimates is a result of the increase(s) in the
>>"quality factors) for neutrons (I believe). There was a very useful paper
>>published several years ago: Health Physics Concerns in Commercial Aviation,
>>Barish RJ, Health Physics Vol 59 No 2 (August), pp 199-204, 1990. It's great
>>to cite during inservices, especially for pregnant women and members of the
>>general public.
>>
>>chris alston
>>alstonc@odrge.odr.georgetown.edu
>>

I do not take issue with these numbers, except to suggest that they are
probably higher than average. There is considerable variation in the actual
dose-equivalent received, as a result of:

		Actual magnetic latitude
		Actual altitude
		Phase of the "solar cycle" ( as noted earlier, cosmic ray fluxes increase
during a solar cycle "low" and vice versa)
		Solar flares (here, flare activity means more cosmic rays,

Someone posted an article recently here saying that his dosimeter recorded
something like 0.1 mrem/hr during a flight. This also is plausible,
although it seems low, espcially if his compact dosimeter did not record
neutrons, which make up 40 to 50% of the dose, using "new" ICRP quality
factors for neutrons. 

The best reference I hav found on the topic is a small booklet published by
EURADOS (Working Group # 11-"The Exposure of Air Crew to Cosmic Radiation",
published as Radiarion Protection 85, Eurados report 1996-01.) It was
written by a blue-ribbon European panel ansnd can be obtained at quite
nominal cost from Bernan Associates in Lanham, MD (Phone 800-274-4447 for
inquiries). THe kind of average dose rate at 30,000 ft or 10 km altitude is
0.5 to .0.7 mrem/h, although they work in microSv, of course. But the
little book has lots of useful information on the causes and kinds of
variation.

The only caveat I would mention relates to the delivery service used by
Bernan. It is not a standard one and does not seem to be overstaffed with
capable people. After the package arrived at the local shipping point, it
took a week of confusion and repeated telephone directions for them to get
it to the destination.


H.B. Knowles, PhD, Physics Consulting
4030 Hillcrest Rd, El Sobrante, CA 94803
Phone\Fax (510)758-5449
hbknowls@ix.netcom.com