The answer to this question really depends on several factors that have to do with your home. For example, living with several shedding pets like cats and dogs can increase the rate that your ducts get dirty. More people in your home also contribute to dust and debris, or if you have a family member who has allergies, they are likely sensitive to air quality. Living off a dirt or gravel road can also add to the dust in your ducts. In general, it’s recommended that ducts be cleaned every three to five years.