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To: lml@lancaironline.net
Date: Wed, 05 Mar 2008 22:17:53 -0500
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From: "Ted Noel" <tednoel@cfl.rr.com>
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Subject: Re: [LML] Re: dry ice in airplane
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A normal person breathing normally at sea level exhales a partial pressure 
of CO2 of 40 torr. That equals a 5.26% concentration of CO2. (I'm an 
anesthesiologist. I watch this multiple times every day on my monitors.) 
Rebreathing in a bag would raise you higher. Also, various drug effects can 
raise your pCO2 as high as 60 or more without any sort of harm. That's 
around 7.5%.

Compare that to a change of 0.5% as noted by Gary. The dry ice effect is 
trivial.

I question the DC-8 story.

Ted Noel

----- Original Message ----- 
From: "Gary Casey" <glcasey@adelphia.net>
To: <lml@lancaironline.net>
Sent: Wednesday, March 05, 2008 9:23 AM
Subject: [LML] Re: dry ice in airplane


>I agree with Ted, but let's do some math to confirm:  First you have  to 
>know the rate of sublimation of the CO2.  I would guess the CO2 is  in a 
>normal cooler and is there to keep something cold, not to cool  something 
>off, so would it sublimate at a rate of 1 pound in 4  hours?  I don't see 
>how it could be that fast, but I'll use that  number.  How much air is in 
>the cabin?  I'm thinking maybe 60 cubic  feet and the air exchange rate 
>would be high, as no airplane is well  sealed - 10 changes per hour?  The 
>weight of the air going through  the cabin at sea level is then about 50 
>pounds per hour.  The CO2  would represent 0.5% or 5,000ppm.  That's pretty 
>high, but no where  near enough to cause suffocation since the O2 
>concentration only  drops by 0.5%.  Stratify the air in the cabin by 
>opening vents at the  front and keep the cooler in the back and the level 
>would drop a  lot.  Someone might know the amount of CO2 normal exhaled by 
>a human  and that would be a good comparison.  The numbers back up Ted's 
>conclusion.
> Gary Casey