As awful as that sounds, it gives you an accurate picture of the air quality you breathe, after it passes over all the crud and decaying debris in your furnace and ductwork. That’s because your ductwork is a lot like your vacuum cleaner.

Every time your furnace runs, things are sucked into your ductwork: dust, pet hair, cooking grease, cigarette smoke, and other debris that will stay in your ductwork until they eventually decay and are released back into the airstream for you and your family to breathe.

Anyone who has ever cleaned underneath or behind their refrigerator knows just how much gunk a fan will collect.

So if you want to know what’s in the dark depths of your ductwork, just look in your vacuum cleaner and see what you’re breathing. This alone is reason enough to get your ducts emptied today.