I posted this link replying in another thread, but want to make sure more people see it. High dose vitamin C can help COPD, read the comments here:
Lypospheric is best, it is a bit costly but you can make it yourself. The Facebook group, Vitamin C & Orthomolecular Medicine For Optimal Health, has tons of info and the members are very helpful.
One of the comments from the above link (it is very worthwhile to read through all of them, except the last four which look like spamming):
"I gave vitamin c to a friend who had been on oxygen in nightime since February.
This was three weeks ago. She has only been on oxygen once since.
I gave her lipsosmal vitamin c (vitamin c in nanoballs wrapped in phosphydatil Choline.) This increases the level of vitamin c ten times over typical oral c."