It's important that your duct system is cleaned every five years to provide a fresh air home for you and your family. Some people get their duct cleaned 20 years or longer. We would recommend cleaning your home duct system every 5 to 10 years. If you don't remember when it's been done then it most likely needs to be inspected. Unclean ducts can affect people with very bad allergies - especially if they are very sensitive to pollen. There could be home air pollution problem if you have pets like dogs and cats. Pet hair all gets into the duct. So it's important for a person's bill of health to have clean ducts to ensure fresh air in the home. The second source of home air pollution is heavy HVAC equipment not functioning correctly. Sometimes your air conditioner won't work with all this pollution floating around in your air duct system. Secondary heat exchangers can get all those things get clogged up in the air conditioner coil. Like a rad in a car all those things get clogged up in the system. Same with the air conditioner; they could get bogged up into the blower. We have one customer that had to get their air conditioner replaced, because all this stuff got sucked into the blower motor air-conditioning unit. From a fresh air home perspective and just overall home health and mechanical systems standpoint, it’s important to have clean ducts.