Homes today are sealed tighter than ever before to improve energy efficiency. The result for many homeowners has been a dramatic reduction of indoor air quality. Replacing the heating and cooling system of your home can be very costly, but there are ways to help improve the indoor air quality without going to that expense.
For existing systems your best bet is to replace the air filters with a two- or three-stage filter which can control harmful airborne microorganisms, gasses, and even dust particles. They may not be readily available at all hardware stores, but most can be purchased online. Be sure to look for high density carbon or polycarbon in the item’s description.
For even greater air quality, consider using a stand alone room ionizer in conjunction with one of these filters.