[trebb]

There is one problem with this. CO2 buildup can kill you.

I wonder how they might manage that - from what I understand, the lack of oxygen doesn't cause one to feel like their suffocating - it's the build-up of CO2. How much CO2 build-up does it take to cause damage if the O2 levels remain good?

[TalonDJ]

We have ways of absorbing CO2 out of the air. Something similar could probably be developed for blood.