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Illinois Country Living

Safety & Health:

Duane Friend, Natural Resources Management Educator, University of Illinois Extension, Springfield Extension Center

Improve your home’s air quality
Duct cleaning and repair can cut down on allergies

Cleaning a house can include many things. This may include having air ducts cleaned.

If no one in your household suffers from allergies or unexplained symptoms or illnesses, and if there is no indication that your air ducts are contaminated with large deposits of dust or mold, having your air ducts cleaned is probably unnecessary.

However, you should consider having air ducts cleaned under the following conditions:

Check to see if there is substantial visible mold growth inside ducts or other components of your heating and cooling system. Be aware that although a substance may look like mold, a lab analysis may actually be needed to determine if it is. Insulation on air ducts that is wet or moldy cannot be effectively cleaned, and should be removed and replaced. If conditions causing the mold are not corrected, mold growth will likely recur.

Ducts may also need to be cleaned if there is evidence that rodents or insects have infested the ductwork, or if ducts are clogged with excessive amounts of dust.

Some dust inside ducts is normal. Much of the dust that accumulates in the ducts adheres to duct surfaces, and therefore is not expelled into the rest of the house. There is no evidence that a light amount of household dust or other particulate matter poses any risk to health.

According to the U.S. Environmental Protection Agency, you should fully understand the pros and cons of permitting the application of chemical biocides or sealants. While the targeted use of chemical biocides and sealants may be appropriate under specific circumstances, research has not demonstrated their effectiveness in duct cleaning or their potential adverse health effects. No chemical biocides are currently registered by the EPA for use in internally insulated air duct systems.

To find companies that provide duct cleaning services, the U.S. EPA suggests checking your Yellow Pages under “duct cleaning” or contacting the National Air Duct Cleaners Association (NADCA). Do not assume that all duct cleaning service providers are equally knowledgeable and responsible. Talk to at least three different service providers and get written estimates before deciding whether to have your ducts cleaned. When the service providers come to your home, ask them to show you the contamination that would justify having your ducts cleaned.

Following a good preventive maintenance program will minimize duct contamination. One of the easiest methods is to use the highest efficiency air filter recommended by the manufacturer for your heating and cooling system. Filters should be changed regularly, probably more often than recommended on the filter.

If your heating system includes in-duct humidification equipment, be sure to operate and maintain the humidifier strictly according to manufacturer instructions.

Research suggests that condensation on or near cooling coils is a major factor in moisture contamination of ducts. The presence of condensation is an important indicator of the potential for mold growth on any type of duct.

When having your heating and cooling system serviced, ask the person to clean cooling coils and drain pans. Make sure ducts are properly sealed and insulated in all non air-conditioned spaces. This will help prevent condensation occurring in those places.

If you do decide to have your air ducts cleaned, educate yourself about duct cleaning methods and ask questions of potential service providers. For more information on air duct cleaning, check out the National Air Duct Cleaners Association website at, or the U.S. EPA indoor air quality website at

Duane Friend is a Natural Resources Management Educator for the University of Illinois Extension, Springfield Extension Center. Contact him at 217-782-6515 or e-mail

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