In a typical six-room home, up to 40 pounds of dust is created annually through everyday living. Your heating and cooling system is the lungs of your home. The system takes air in and breathes air out. Through normal occupation in a home, we generate a great deal of contaminants and air pollutants, such as dander, dust, and chemicals. These contaminants are pulled into the HVAC system and re-circulated 5 to 7 times per day, on average. Over time, this re-circulation causes a build-up of contaminants in the ductwork.