Hi Ethan...welcome aboard!

I do have a quick question for the group ….I flew last Thursday for the fist time in 6 years since my disability. Prior to that I have flown over a 1,000,000 miles.
I have an Oxus POC that took with me. While in flight I checked my o2 several times getting readings from 61-75% , my usual readings are 88-92% . I wonder if the purity of the o2 in an aircraft might be slightly less than normal causing the concentrator to not produce as good? Plus I think I had the begging on a flare.
I'm heading back Monday and its a 2 hour flight so not too long.
Any and all feedback is greatly appreciated.
Breathe easy