I've seen the NHS about 4 months after seeing a private hospital. The private hospitals readings were worse for me than NHS (I'll try and dig them out) but here is what the NHS tests found...
"Investigations: Lung function test done.
Fev1 showed 80.3 percent predicted, vital capacity 85 percent of predicted whereas ratio 73.72.
What does that all mean?
Apart from I've been checking my sp02 regularly. It can go as low as 90, 92 and then 94, 95, 96, 97 and sometimes 98.
My partners does not vary so much.