During the winter, you had your furnace on a lot. Each time it ran, the air it blew through the ducts and out the vents would circulate the air in your home. Anything in the air would circulate as well, including dust, pet dander, and pollen. When the furnace shuts off, these airborne particles settle, often in the ducts themselves. Plus, furnaces can suck these particles in through intake vents, redistributing them again.
Without regular cleaning, furnace ducts can accumulate layers of these pollutants, providing an ample source of them each time the air blows, thus compounding the problem.
Here are 4 reasons why you should get your ducts cleaned by a professional, now that your furnace is hibernating:

1. Clean the air

As mentioned above, ducts can collect dust, pet dander, pollen, mold spores—and if you have small children, all sorts of other objects. Cleaning the ducts gets rid of this buildup, improving your home’s air quality.

2. Reduce allergens

Many of the particles accumulating in your ducts are common allergens. By cleaning out your ducts, you may reduce the severity and frequency of your allergic reactions.

3. Change your filter

Since you’re cleaning your ducts anyhow, be sure you replace your filter. If allergens make it through the intake vent, the filter can prevent them from travelling further.

4. Save money

If your ducts are clean and you have a clean filter, air will move more freely, which means the furnace won’t have to work as hard, saving you on natural gas and electricity costs.