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 taken air in and breaths air out. Through normal occupation in the 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 an average. Over time, this re-circulation causes a build up of contaminants in the air ducts.