Courtney's advice is good. A professional job of cleaning ducts will make a tremendous difference in air quality. I had chronic sinus infections for years until I did the following: cleaned the air ducts, started changing the filters regularly, puchased a good air cleaner for the bedroom ( I travel with it), kept the house cold in the winter avoiding dry heat and using a neti pot each night before bed. No more sinus problems. You can do duct cleaning yourself after the initial cleaning by taking the vent plates off, washing them, vacuuming out inside the duct as far as you can go, then replacing the plates.