The "normal" oygen saturation is about 88 - 92%. Below 88 when moving or asleep is probably a sign for Oxygen therapy. Others can still be uncomfortable within that range while just sitting at rest. Remember, the Oxygen does don't help you breathe better, but only to ensure there is enough circulating in the system when you are not. Your Doc can help you isolate why the O2 use does not seem to benefit you.
Remember, THC is a system depressant and will reduce the breathing rhythm even in healthy people.
Be well.

You are probably air-trapping. You're not getting rid of the stale air to make room for O2. Purse lipped breathing will help as will diaphragmatic breathing. If this is happening to you during exercise, know that you can continue to work as long as you can stand it and you won't do yourself any harm. You'll be uncomfortable, but you won't hurt yourself.

No; not that person, but what is a good ratio?

THC is actually a broncodialator if I spelled that right. It opens up your airways

RollandO great and correct explaination about O2 saturations