Well yes, in fact in doing the research for my previous post I found that the oxygen concentrators are really nitrogen scrubbers, They do not so much concentrate the oxygen as scrub out the nitrogen Then exhaust it back into the room.. Removing the Nitrogen (Which is the largest part of the air we breath) concentrates all the other gasses in the mix.
Often, as in this case, I think I know something, as I did here, but just to be sure I will do the research (Again as I did hear) In this case I learned something tangential (how they work), but there was no surprise. In other cases, I've been surprised. I actually enjoy research.