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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
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