As spring cleaning gets under way in many American households, duct-cleaning products company Rotobrush International is reminding the public that not all dirt is visible.

Debris is likely sitting in the ductwork of many HVAC systems — many of which saw heavy use during the record-cold winter that gripped many sections of the country.

HVAC contractors should remind homeowners that their systems may need cleaning.

“Air ducts are just like any other part of the home or business, dust and dirt can accumulate and build up if you don’t perform proper care and maintenance,” said Lane Jeffryes, CEO and president of Rotobrush International. “Think of how much time you spend at your home or office. It’s important to make sure you have an environment where you have access to healthy air and feel comfortable.”

Animal dander, dust mites, pollen and mold spores may be sitting in ducts and find its way into the home when central air conditioners or furnaces are turned on, the company said.

“Homeowners are looking for ways to improve their surroundings and increase the health of their home,” Jeffryes said.

Schools should also consider cleaning supply diffusers, registers and intakes, change filters and ensure proper ventilation, the company added.