Hello Rick.
I have read many of your posts and you have been kind and responded to my questions also.
Interesting: "moved from Denver to sea level and have no used o2 at all. " That must have required a great deal just to do that.
Your discovery reminded me of what happened with my Mother who was diagnosed with Emphysema. Mother smoked for 50 years. My parents had a winter condo in Florida on the 19th floor. Mother, once the emphysema progressed to a certain point, did very poorly at that building height and they had to stop going to the condo.
We make changes in life for all different reasons.....one being our health.
Barbara