What I can suggest, and what I am using, is a 'whole home' electronic air cleaner.
These units install right in the return air duct of your central heating and cooling system. There are some units on the market like, Trane CleanEffects, that will purify the air down to .01 microns. This will scrub the air of 99.98% of mold, mildew, influenza, allergens and the like.
Some folks like to use small portable air cleaners but, frankly, these do not perform as well as a whole house unit in delivering clean air. Plus, they are really only good for a single room or area. Others use what are called "HEPA" filters and 4" pleated filters in their furnace, and these are good, but again. they do not capture 99.98% of pollutants and they do not capture influenza virus. So, to breathe easy at home. To save money by not going to the doctor so much. To ease up on your purchase of over-the-counter allergy medication and perscription medication. Invest that saved money in a whole-home air cleaning system. For more information, check my other blogs at email@example.com or go to our website at www.greensheating.com.