"How important is air-duct cleaning? How often should it be done? Is it worth it to pay the extra money to ensure there is no mold in the airducts?" — Angie's List member Glenn G. Millar

According to John Anderson, co-owner of AAA Anderson’s Furnace, Duct and Appliance Repair in Forest Lake, Minn., the biggest benefits are less dust on furniture surfaces, improved air quality and greater HVAC system efficiency.

“You’ll have less dust circulating, and anyone with allergies, asthma or sensitivity to dust will have an easier time breathing,” he says.

However, the Environmental Protection Agency says that there isn't any scientific evidence that regular duct cleaning improves air quality, according to their 1997 brochure. "Checking and changing filters, keeping systems maintained, having regular inspections, and ensuring moisture doesn't get in are more important," says Laureen Burton, senior scientist in the EPA Indoor Environments Division.

Both EPA and the National Air Duct Cleaners Association – which represents more than 1,000 cleaning companies nationwide – do agree that there's some value in the work.

Thomas Keys, president of Atlantic Duct Cleaning Inc. in Sterling, Va., recommends performing duct cleanings every five to eight years, unless someone in the house has immune system or respiratory problems, in which case it should be inspected every two years. He suggests that anyone hiring a duct cleaner search for a firm certified by the National Air Duct Cleaners Association.

In the Southwest, experts advise that cleaning should be done every three to five years. “[Homes] can get pretty dirty and dusty with the dust storms around here,” says to Sharon Altenhoff, CEO of Air Quality Specialists Inc. in Glendale, Ariz.

In addition, you should have air ducts cleaned after having work done on your home. Salvatore Scianna, owner of Dependable Duct Cleaning in Sandy Hook, Conn., advises cleaning ducts shortly after major construction or remodeling. “There is a lot of saw dust and fine Sheetrock dust that gets in the ducts,” he says.

Duct-cleaning costs vary by region and size of home, but Giuliano Cuete, owner of Airwiz in Germantown, Md., says it should range between $300 and $1,000.

“Stay away from offers that seem too good to be true,” Cuete says. “If you get a coupon that promises to clean your whole house for $99, it’s probably a scam. Air-duct cleaning is not a cheap service.”

If you have mold concerns, Doug Long, owner of Power Vac America in Houston recommends having an Environmental Protection Agency-registered sanitizing agent applied to rid the duct system of biological contaminants such as mold or mildew as part of a regular duct cleaning.

Michael Horstman, owner of Apex Duct and Chimney Cleaning in San Marcos, Calif. advises using pleated HEPA or electrostatic filters to maintain the air duct system and lenghten the time between duct cleanings. Pleated filters should be replaced every 90 days, and electrostatic filters need to be cleaned every month.

“A good quality filter is a big factor in getting better air quality,” says Manny Hamideh, owner of Westchester Air Duct Cleaning Inc. in Montrose, N.Y.

“Maintaining a clean air conveyance system may reduce your utility bill by $30 per month by reducing the time your system runs,” says Tom Mawby, owner of Ductworks Inc. in Cleveland Heights, Ohio. “This results in less wear and tear of your furnace, saving you money on expensive repairs.”

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