Atmos. Pressure

                       Subject:                               Time:8:09 AM
  OFFICE MEMO          Atmos. Pressure                        Date:5/19/94
James T Perkins [email removed] wrote:

>Humans are used to breathing area that is 80% N2, 20% O2. The air
>pressure they breathe it at is 14.7 lbs/in^2. The partial pressure of O2
>is about 0.20 * 14.7 lbs/in^2, or about 2.9 lbs/in^2. This is the
>theoretical minimum air pressure that humans can sustain while still
>being able to get adequate oxygen supply to their cells. The practical
>minimum air pressure, however, tends to be higher than this -- for one
>thing, altitude sickness may set in at this low a pressure (bodily
>fluids filling up the lungs). Also, pure O2 is only wise for short
>periods as it tends to oxidize the linings of one's lungs.

A 1960's era Rand Corp. published study "Habitable Planets" covered this issue,
among others, in some detail.  It may be avaliable in large university
libraries, it was at my university.  It is recommended reading for anyone
interested in what type of planets humans could live on.  It has been over 5
years since I last checked it out and I can not recall any details but it
provides upper and lower limits of oxegen, atmos. pressure, temp etc.

If anyone has easy access to a university library a short summary of its
conclusions would be beneficial to the mailing list.

Kevin Mc Carthy