Is Mold in Air Vents Normal?

To some extent, mold inside your home can not be avoided. According to the Centers for Disease Control and Prevention, mold is everywhere. It is floating in the air--outdoors and indoors. For those with respiratory problems or those who are sensitive, molds can be the culprit for anything from mild irritation to severe reactions.

Close up of mold.
Close up of mold. (Image: Ingram Publishing/Ingram Publishing/Getty Images)

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Mold in the Home

Is it possible to prevent mold from entering your home? Not likely. One of the many ways mold can enter your house is through an air vent or the heating and air conditioning unit.

Air conditioner outside home.
Air conditioner outside home. (Image: Jupiterimages/liquidlibrary/Getty Images)

Is Mold Present?

To determine if mold is actually lurking in your vents, take a good look. According to the National Association of Certified Home Inspectors, mold might resemble “a fuzzy, thread-like, cobwebby fungus.”

In addition, mold may appears as spots or different colors, and it often has a distinct odor. Take a good look–and a good whiff--at the vent. It is best to go ahead and treat the vent if you see or smell mold, without taking steps to determining exactly what type of mold might be present. According to the CDC, the type of mold isn’t important. What is important is to take steps to remove the mold.

Air conditioner vent.
Air conditioner vent. (Image: Jupiterimages/ Images)

Dust is Normal

Air return registers will get dusty as air passes through them, and being dirty is not a sign of mold being present. Removing the vents on a normal basis for cleaning will prevent dusty build-up.

While it is best to clean any visible mold, keep in mind the fact that mold spores are microbial and can not be seen by the human eye.

Dust on vent.
Dust on vent. (Image: Fedor Kondratenko/iStock/Getty Images)

No Studies

Since mold spores aren’t visible, some homeowners consider having the entire duct system of their home cleaned. However, the Environmental Protection Agency does not recommend this procedure for households who are not experiencing respiratory problems. In fact, the EPA states that no studies have proven duct cleaning will prevent health problems.

Keep air conditioner clean.
Keep air conditioner clean. (Image: Alexandru Dobrea/Hemera/Getty Images)

Time to Clean

The EPA recommends cleaning your home’s air ducts if mold growth is visible in the ducts or on the components of the HVAC system. Other reasons for extensive cleaning include evidence of rodents or insects, and debris being blown from the registers.

Repairmen working on home.
Repairmen working on home. (Image: Juri Semjonow/iStock/Getty Images)


If you are determined to avoid mold growth in your home’s vents, the Environmental Protection Agency says the best form of preventive maintenance is to stay dry. Water and dirt in the HVAC system tends to breed mold spores, which are then released to roam free through the living areas of the home. Symptoms such as allergies might then be irritated by the contaminants.

Flooded house.
Flooded house. (Image: Image Source/Digital Vision/Getty Images)


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