>I think the time after which brain damage begins is 4mins.
I get minor damages reports faster than that. When they start seems to
also depend on wether I expect it and am used to holding my breath or
not, and if I move or am very still while not breathing.
Wildly theorizing around a sort of damages distribution system MIGHT
be alike the one I theorized with some MBD folks as embryos.
(Brain stem late, neocortex and own thinking areas faster.)
BTW, I heard some pearl divers are able to stay under water for quite
a while. Don't believe that for someone trained and someone not
trained, and all humans of Earth the times for different sorts of
damages due to lack of oxygen are exactly the same.