Here are tips on how to hire a specialist to clean your air ducts:

• Avoid the bait and switch: Many air duct cleaners send mailers that advertise one low rate for a whole-house duct cleaning. Glenn Fellman, executive director of the Indoor Air Quality Association, says those offers don’t include the detail work of a true thorough cleaning, and you’ll likely end up paying more.

“If you’ve got a modestly sized house, 2,500 square feet or larger, don’t expect to pay less than $500. You’re probably going to pay between $500 and $1,000,” Fellman says.

• Adhere to the standards: Be sure the person you hire cleans in accordance with the National Air Duct Cleaners Association (NADCA) standard — ACR-2006.

“We tell consumers to write that on their bill of sale because that’s their contract,” says John Schulte, executive director of the NADCA.

• Go beyond vents: Air duct cleaning isn’t just about sucking the dust out of your vents. It involves cleaning anything that air passes over in the HVAC system, says Buck Sheppard, board president of NADCA.

• For more information: Get the NADCA cleaning standard and an air duct cleaning checklist at nadca.com. Watch our podcast on air duct cleaning at angieslistpodcasts.com.