Why should air ducts be cleaned?

Studies have shown that indoor air can be 2 to 5 times MORE polluted than outside air. Most disposable filters remove about 10% of these pollutants allowing 90% to enter the air system, even during the construction of a new home. The pollutants contain dust, pollen, mold spores, animal dander and much more. These materials collect in the furnace, air conditioner and duct surfaces, just as they do on the furniture and floor surfaces. The furniture and floor are cleaned regularly but the duct surfaces are hidden from view and can only be reached by specialized duct cleaning equipment. These pollutants can migrate out into the room again, or become a food source for mold and bacteria, which can thrive in this dark comfortable environment from high humidity or moisture from the air conditioner or humidifiers. Biological growth can release mold spores or toxins into the air system