Sorry I used that analogy HashHands, didn't mean to muddy the waters with the heat aspect.

Try this one instead; same room, same size and same temperture. One room is at 30% relative humidity the other at 95+% humidity, now see how much work or excersie you can do in each. Breathing will be more difficult in the high humidity room vs the low humidity room.

I was trying nicely to point out to you that your contention that 100% humidity with 100% oxygen is scientifically wrong.