According to the EPA, levels of air pollution inside the homes can be two to five times higher than outdoor levels. Household dust can contain mites, mold, mildew, pollen and animal dander- all of which is cycled through the central Air system, which completely circulates the air in your home three to five times a day. Cleaning your ducts can reduce this indoor pollution and help remove these contaminants from circulating through your home and lungs.