> What is the greatest depth any gas may be breathed
> indefinitely and safely, without ever requiring
> 'formal' decompression, and what is that gas?

Originally, I posted my answer as air at sea level.  Revisiting the
question, however, gives me the correct answer.  There is no gas that may be
breathed indefinitely and safely without ever requiring formal dcompression.
In fact, there is no gas that can be breathed indefinitely since there's no
human that can breath indefinitely.

My, you can tell things are slow when I revert to garbage like this.  I just
spent 4 hours and a number of formerly writable CDs trying to make a backup
for one of my coworkers.  As a last ditch effort, I checked the original . .
. which of course had a major scratch right across the data portion.
Grrrrr.  Now I have to find an undamaged original and make two copies.

Lee