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 air ducts? — Angie's List member Glenn G. Millar

According to Manny Hamideh, owner of highly rated Westchester Air Duct Cleaning Inc. in Montrose, N.Y., air duct cleaning is very important because of the amount of dust it removes. "It's very easy to trigger allergies, and dust is not good for your lungs, " he says. "Air-duct cleaning is the best home improvement you can make."

Hamideh recommends cleaning ducts every three to five years. The average job should take about 4 hours and the cost should begin at about $400. Those who charge dramatically less are probably not legit, he says. "They use it to get their foot in the door, then they start tacking on additional charges," Hamideh says.

Salvatore Scianna, owner of highly rated 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.

To help lengthen the time between duct cleanings, Hamideh suggests changing air filters every three months. "A good quality filter is a big factor in getting better air quality," Hamideh says.

Scianna cautions against hiring duct cleaners who push the threat of mold too greatly. "Every house in the world has mold in it, and not all of it is harmful," he says. "If someone is pushing the mold angle, that's a flag of a possible upsell.

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