Partial Pressure of O2 is what's important.
If you have more oxygen, you need less pressure to get enough into your bloodstream.
Earth's atmosphere is about 21% oxygen. If you could get the air in the habitat to 50% oxygen, you would need that much less pressure.
(Of course, people traveling back and forth between the habitat and Earth might have some problems with the pressure differences)
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Partial Pressure of O2 is what's important.
If you have more oxygen, you need less pressure to get enough into your bloodstream. Earth's atmosphere is about 21% oxygen. If you could get the air in the habitat to 50% oxygen, you would need that much less pressure. (Of course, people traveling back and forth between the habitat and Earth might have some problems with the pressure differences)