O2 suitcases & post Apollo1 launchpad atmosphere question
I am familiar with the astronauts using these suitcases to carry their pure oxygen on their way to the launchpads. From my reading it sounds like it is used a bit as "air conditioning" but more importantly to get "rid" of the nitrogen in their blood by only breathing in O2 a few hours before launch. The low pressure 5psi environment, as I understand, would cause the nitrogen to come/bubble out of the blood and result in pain, usually showing up in joints. Mike Collins references this in his book in his Gemini 10 flight where he ended up taking some pain killers for his knee.
However after the Apollo 1 disaster, one of the procedure changes was to use a nitrogen and oxygen mixture to prevent a highly combustible environment.
So my question is, would this N2/O2 launch environment re-add the risk of getting the Bends in your joints once up in space? And if so, why would they continue to use pure O2 briefcases prior to launch when they would then be reintroduced to N2?