Re: In-flight radiation -Reply

["Jim Thurston" <jimbobs99@hotmail.com>]

Hi there,

Just to add a short note to this topic:

Concorde flies at up to approx 65,000 feet (most other passenger planes at 
35-37,000 max).  Concorde is fitted with a dose rate monitor with a read out 
in the cockpit.  If the dose rate rises above 12microSv per hour, normally 
during raised sun activity, the pilot is required to descend to lower 
altitude to reduce the rate.

Note that in the UK the current dose rate limit for defining a "Controlled 
Area" is 7.5microSv/hr, requiring the classification of workers routinely 
exposed if their overall dose is likely to exceed 3/10th of the annual dose 
limit (3/10th of 50mSv = 15mSv).

(By comparison, National Radiological Protection Board data show that a 2hr 
flight on a normal passenger plane (say between London and Madrid) would 
give an extra radiation dose above normal background at ground level of 
approx 10microSv - i.e. 5microSv/hr).

Regards,
Jim Thurston


>From: Mutty Sharfi <SHARMM@doe-md.gov>
>Reply-To: radsafe@romulus.ehs.uiuc.edu
>To: Multiple recipients of list <radsafe@romulus.ehs.uiuc.edu>
>Subject: In-flight radiation -Reply
>Date: Tue, 16 Nov 1999 12:52:54 -0600 (CST)
>
>Silvia,
>
>To your question of how flight crews can be protected, the main
>principle in radiation protection is not to be in the path of it.  
>Therefore if
>you know the average exposure per flight (probably more like per hour
>of flight and altitude) one can adjust flight crew schedules (by reducing
>flight time) to minimize the potential of overexposure.  It is to my
>understanding that a single cross country flight (LA to NY) is only a
>couple mrem.  Therefore, to reach the DOE limit of 5 rem (5,000 mrem), a
>flight crew would have to fly almost a 1,000 or so flights which is not to
>common (3 flights per day 365 days a year).  However, ACLs
>(Administrative Control Limits) are set sometimes up to a factor of 10
>below the DOE limit to ensure compliance (2,000 - 500 mrem).  Therefore,
>if an ACL of 500 mrem was used, it is very possible to exceed the ACL.
>I would remind you that passing the ACL is not considered to really
>increase in risk of cancer to the individual (but that is another debate; 
>the
>debate on LET).  The DOE dose have guideline for planned exposures up
>to 25 rem (25,000 mrem).
>
>Another interesting note:
>
>The most interesting part of flight crews and radiation is on pregnancies.
>To my understanding the time at which a fetus is most sensitive to
>radiation is the second trimester. I have been told by flight attendants,
>that the airlines warn passengers about the risk to exposure to all
>pregnant women (pointing out the point about the second trimester), but
>when I comes to their own flight crews, a woman cannot (I probably
>shouldn't say cannot, maybe just that they are not compensated if the
>take off) take off till she is in her third trimester (meaning she must fly
>and expose the fetus during the second trimester; the time at which the
>fetus is most sensitive to radiation).  Don't know if this is true for all
>airline or what, just what I was told.
>
>Well, I hope this helps you.  Enjoy.
>
>****************************************************************************************The 
>opinions expressed above are mine alone and my not represent the
>opinions of my employer of the DOE.
>****************************************************************************************
>
>Mutty Sharfi
>Internal Dosimetry
>Mound Site
>BWXT of Ohio
>sharmm@doe-md.gov
>
>
> >>> CARFORA SILVIA <atomica10@home.com> 11/14/99 10:10pm >>>
>Hello,
>
>I read the Radsafe archives on in-flight radiation and I think that crew
>members should be aware of health risks associated with radiation
>exposure.
>Dose monitoring is important, but how can flight crews protect
>themselves from radiation?
>Can individual radiation dose be lowered?
>How can their work environment (the aircraft cabin) be used to help
>lower the levels of radiation, crews are normally exposed to?
>
>I am a student researching in-flight crew radiation exposure and the
>related health risks.
>Any information would be greatly appreciated.
>
>Regards,
>
>Silvia Carfora
>atomica10@home.com
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