On Tue, 30 Nov 2004 10:36:12 -0600, in a place far, far away, Earl
Colby Pottinger made the phosphor on my monitor
glow in such a way as to indicate that:

Why does prebreath take so long? Bubbles? But at the lower pressure tere is
not that much gas in the blood, is there? People often dive to 30 to 50 feet
and come back up in time measured in minutes not hours. So why so long?

Because it's a sudden pressure drop. It takes time to get the
nitrogen level down sufficiently to prevent the bends going from 10.2
to 4.3.

And
if caution is the main reason for such a long time how much can it be cut
back for an emergency?

Not much, unless life is threatened more than the bends.

The best solution to the problem would be a mobile, high-pressure
suit, but NASA's never developed one.