Sandy's question(s) seem to have become mired in the "Brovana" posts, so let's start a new topic.
If might be helpful to discuss your mouth breathing with the RT at your rehab facility. Understanding your limitations are part of his/her job. Perhaps they have masks available for patients. However, I think the biggest problem is WHY your nasal passages stayed clogged.
Humidity and I are not friends; I live with a dehumidifier going most of the day but it generates a lot of heat and I have to constantly shut it off until the humidity gets above 43% then I have to turn it back on - like my old Scottish Grandmother used to say - "No rest for the weary."