I was watching Smarter Every Day's episode on hypoxia, and it had an interesting chart that suggested that at 35kft, you have less than 10 seconds of useful consciousness. This number seemed low, and I'd like to know why.

I have two pieces of evidence that make me question the chart (even though I know Destin from Smarter Every Day doesn't make mistakes lightly):

  • I can hold my breath after an exhale and function for well more than 10 seconds
  • It seems to me that the vacuum of space would be the ultimate test for how long you can sustain consciousness without oxygen, as the vacuum of space literally strips oxygenated blood as it passes through the lungs. Wikipedia cites sources claiming you go unconscious in under 14 seconds, and a case of accidental vacuum exposure that resulted in a loss of consciousness in 15 seconds.

So why is it that the "useful consciousness" table seems to contradict these datapoints?


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