I had severe acute bronchitis last winter followed by long-term recovery with assistance of corticosteroids -- ended up in Urgent Care twice and the ER once, I believe largely since nobody seems willing to prescribe strong antibiotics these days except when it approaches malpractice.
Anyway, I have been supporting my lungs' ability to rebound hopefully completely, and so last winter I bought a couple air purifiers to help with that, and in part as a defensive measure due to a nearby neighbor who likes to burn noxious wood in his woodstove in winter, and his crap smoke blows against my house.
I also have low to moderate seasonal allergies to pollen/grass/trees/mold.
Anyway, in case you're interested you might at least seasonally consider an air purifier. The one via the link below is whisper quiet, works very well, and has provided me with lots of relief and clear air passages, both lungs and sinus, especially overnight via the one in the bedroom. My other one is in my living room.http://www.amazon.com/gp/product/B0067D7CKU/ref=oh_details_o05_s00_i00?ie=UTF8&psc=1