> It is the period of time from the interruption of the oxygen supply or exposure to an oxygen-poor environment to the time when useful function is lost, and the individual is no longer capable of taking proper corrective and protective action.

> It is not the time to total unconsciousness

35,000 feet is 30-seconds to 1-minute of total useful consciousness, half that for rapid decompression situations.

I stand by my estimate for "Dozens of seconds before you're an idiot". Most people will remain conscious after this time is up: they just will have become such idiots that its unlikely they will ever be able to fix their Hypoxia condition. (Slurred speech, unable to dexterously control your limbs, etc. etc. You're conscious, but no longer capable of putting on a mask even if it is dangling in front of you)

Wikipedia takes the table from an FAA document: https://www.faa.gov/pilots/training/airman_education/media/A...

There's pretty much no reason to measure "time to unconsciousness", because you're incapable of helping yourself long before you're unconscious.