Air duct cleaning is one of the fastest growing businesses in the IAQ field. The air ducts are the "lungs" of a building. Over time, dirt, dust, debris, tobacco smoke, animal hair, dander, and other contaminants can accumulate inside the duct work. Dirty ducts can also become an ideal breeding ground for pollen, mold spores, mildew, bacteria, and other potentially harmful bio-pollutants which can pass easily through the furnace filter and into the air we breathe.