FlyerTalk Forums - View Single Post - AA Passenger Facial Cover / Mask Use Policy 2020 (Inc. changes)
Old May 3, 2020, 12:43 am
  #49  
JDiver
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Originally Posted by TBRIC
I’m not a physician, but since commercial airliners are only pressurized to the equivalent of 6-8,000 ft altitude, wouldn’t there be a chance of hypoxia with some people, depending on the type of mask? Especially on a longer flight?
A mask doesn’t filter gasses. But at 8,000 feet / 2,438 m of altitude, the effective percentage of oxygen is 15.4 %, rather than the 21% it is at Mean Sea Level. And at 10,000 ft / 3,048 m it’s 14.3 % and above 10,000 supplemental oxygen is required for aircrew. That 15.4% can be a significant problem for some people and result in dangerous levels of blood oxygen saturation. The mask wouldn’t have any effect other than the resistance it might provide to unrestricted breathing.

E.g. A few years ago my wife was recovering from a difficult pneumonia and sepsis (10 days on sedation and ventilation in ICU) and we had a trip planned that included 13 hours in a 777 (LAX-LHR). That was a concern to me so after consulting with our doctor we drove to a spot in the Sierra Nevada and spent the day taking periodic readings with a pulse oximeter. Her SPO2 remained at 95% all day, so we traveled. (I’m not a doctor, but was certified as a medic and oxygen provider, mixed gas tech diver among others.)
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