----- Original Message -----
From: "Huw Porter" <[log in to unmask]>

> I've had a trivia question in the back of my mind for a while, and while
> it's so quiet, I'm going to ask it.
>
> ------------Qn:------------
> What is the greatest depth any gas may be breathed
> indefinitely and safely, without ever requiring
> 'formal' decompression, and what is that gas?

For Human Beings?  I don't believe that you will find such a gas.

Mike