> All I need is the air that I breathe...
> ---------------------------------------
>
> One of the hazards of space travel is going to be running out of breathable
> air. When considering a particular 'scene' for a scenario I was
> planning, I realised I had no good idea of how long it takes a person
> to use up the available air in a sealed room. So, some questions for
> the list.
>
> Imagine you are in a sealed room. How long does it take a person to die
> because the air gets bad - and why? Is it lack of Oxygen, or the
> presence of impurities?
>
> If the room is filled not with air, but with Oxygen only:
> - what atmospheric pressure should it be at to be safe? I believe that if
> the pressure is too high the atmosphere promotes any sort of minor
> spark into a serious fire/explosive hazard.
>
> - how long before a typical human unfortunate dies from bad air in this
> scenario.
At the a high atmospheric pressure oxygen becomes toxic. This is the reason
Scuba divers use compressed air instead of oxygen. At normal pressure the
fire risk from an all oxygen atmosphere is very high.
The breathable air in a room is converted to bad by a person consuming
oxygen which is replaced by carbon dioxide. Eventually the lowering oxygen
levels will cause a person to die from oxygen starvation. At which point
I don't know but the amount of oxygen used by a person depends upon their
activity rate. By doing little the air in a room can be made to last longer.
Away to extend the time a person has in a sealed room is to have someway
to replace the oxygen. If there was a bottle of compressed oxygen in the
room it could be opened occasionaly to increase the oxygen levels. This
may have to be done carfeully if there is no gravity in the area. If a valve
on a bottle of compressed gas is broken, the bottle can smash through brick
walls.
- --
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* David Hoey * Computer Science, Northern Territory University *
* [email removed] * Darwin, Northern Territory, Australia *
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