Are these duct cleaning ads on Facebook legitimate? Not according to the National Air Duct Cleaners Association, which warns about "air duct cleaning scams on Facebook.". The industry group ...

"Duct cleaning has never been shown to actually prevent health problems. Neither do studies conclusively demonstrate that particle (e.g., dust) levels in homes increase because of dirty air ducts.

Air duct cleaning typically costs about $270 to $500, with an average cost of $388. Your cost depends on the number of vents, the type and size of ductwork, and where you live.