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5 Signs Your Air Ducts Need Cleaning

How clean are the ducts that circulate air in your home? You may not realize it, but dirty air ducts do contribute to poor indoor air quality and health problems. Dirty ducts can worsen your allergy symptoms if you’re an allergy sufferer. Grimy air ducts can also create other issues in your home, including problems with your heating and cooling system.

Home owners tend to clean the inside of their home, but forget to have the ducts cleaned regularly. Dirt, debris, and even mold continue to accumulate over time.  While some homes require duct-cleaning far less often than others (and it’s very seldom an annual need), let’s look at some signs that you need to hire professionals to clean your home’s ductwork.


It may not seem like air ducts have much to do with allergies, but they may be connected in a surprising way. The ductwork in your HVAC system is usually located next to your ceiling, and every time you turn on your air conditioner or heater, its blower begins circulating contaminant-laden air through your home. This can be minimized with regular air filter replacement, but without a dedicated air cleaner, there’s still some amount of dirty air circulating. It often contains particles containing contaminants ranging from dust mites to pollen to mold spores and more, all of which can trigger allergies.

If you live in an older building where these ducts are exposed (prior to being covered by drywall or insulation), even a quick look will confirm they’re an ideal breeding ground for allergens: blackened grime covers the inside of the ventilation shafts; animal hair has collected on top of them; and debris has built up over time.

It’s easy to overlook this problem because most home occupants don’t suffer from severe allergies. But if you’ve ever had trouble breathing at night, or experienced chronic sinus infections or hay fever symptoms, you should consider a professional duct cleaning every few years, especially if you have allergy-suffering, very young, or older family members.

Dusty Furniture

If you have a house, chances are you’ve cleaned the floors at one point or another. If the average home has carpeting, it’s even more likely that you’ve vacuumed your rugs. But what about cleaning up top? Sure, a fan might help circulate some air and keep down dust bunnies, but if your house is like most in America, it probably has air ducts in need of a deep cleaning.

Take a close look at your furniture. If you notice dusty furniture after you clean and declutter your place, it may be a sign that your forced-air HVAC system isn’t doing its job properly, and is blowing dust throughout your home during heating/cooling cycles. You should also check the vents themselves for signs of dust buildup whenever possible — just look at how thickly coated they are near the grates or along their sides.


Mold can grow almost anywhere, including in your air ducts. Mold flourishes in dark, damp, and moist places. If you see black or green spots on your vents or ducts, or notice a musty odor coming out of them, they may have mold growing inside — and that’s bad for your health. According to the federal Centers for Disease Control and Prevention (CDC), millions of Americans suffer from respiratory infections each year. Mold spores can exacerbate these infections by causing inflammation in the lungs and mucous membranes.

A comprehensive duct cleaning generally must be done by professionals, since in most homes, the great majority of ducts are inaccessible without specialized equipment. It’s not something an ordinary homeowner is equipped to do. In addition, the professionals have high-tech diagnostic equipment that can access how badly your ducts need to be cleaned and where.


Your air ducts are a veritable maze of metal and plastic, so it’s no surprise that they can quickly become home to various insects and vermin. Rodents, insects, birds, snakes, bats — any one or a combination of these critters may make their way into your ducts over time. All the junk stuck in there is the perfect feast for a raccoon or possum. In addition to the animal waste in your ducts after not cleaning them often enough, these pests can also leave behind waste or their own carcasses. This isn’t something you want to breathe in 24/7.

Bad Smells

If you notice an unpleasant odor coming from your vents, it may be because they need cleaning. The air ducts in your home are often neglected, but cleaning them can improve the quality of the air in your home and even lower your energy bills. Clean ductwork allows for smooth airflow, saving energy and improving home comfort. Here are some signs that you might need to hire a professional:

  • You notice a bad smell
  • Your HVAC unit isn’t working as efficiently as it could be, and other common causes have been ruled out
  • Visible debris, usually near vents or registers
  • Evidence of mold
  • Evidence of insects or animals, either from their smell or noise.

As stated, many homes’ HVAC systems do a good job of filtering and/or cleaning the air before it circulates in the home. These homes can go years without needing a professional duct cleaning. However, the only way to find out for sure is to hire a reputable HVAC contractor that will inspect your ducts and determine whether professional cleaning is necessary. Beware of unscrupulous outfits that will do a quick inspection and offer to clean your ducts for a high price. Always work with an HVAC outfit that you trust.

The Bottom Line

If you are aware of any of these signs that your air ducts need cleaning, your ducts may need to be cleaned. As with most home services, the sooner you act, the better. You may not think air duct cleaning is important, but it could be the key to a more energy-efficient home and healthier breathing environment.


“Mold and Health – US EPA.” 29 Mar. 2021, epa.gov/mold/mold-and-health.

“Mold Danger: Can Mold Cause Lung Cancer? – WebMD.” webmd.com/lung-cancer/guide/lung-cancer-and-mold.

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