A: They don't get very dirty year to year in most homes. Regular duct cleaning isn't necessary. However, don't confuse duct cleaning with furnace check and tune up. That should be done regularly, preferably every year.

Most of the time, yearly duct maintenance is a do-it-yourself job. Vacuum clean the registers and grilles. Remove them and clean inside as far as you can reach.

But do consider having the ducts cleaned if you have:

—A newly constructed home.

—An existing house that has been remodeled or was under construction.

—Purchased a home and don't know if the ducts have ever been cleaned.

—Lived in your home for more than 10 years and have never had the ducts cleaned.

If it's dust you are trying to control by duct cleaning, it's better to consider:

—Carpet. Carpeting sheds fiber and collects dust particles. Every time you walk on it, you knock particles into the air that circulate throughout the house. Synthetic carpets and pads deteriorate over time, becoming brittle and breaking into fine particles, which contributes considerably to dust. Replace old carpet and pads, or, when possible, remove them and use hard-surface flooring and area rugs.

—Pets. Furry pets shed hair and dander. Launder their sleeping areas frequently, and bathe and groom animals regularly.

—Vacuum cleaners. Cleaning with a vacuum can help control dust, but if you don't use one with a HEPA filter you'll simply spread around the dust. A central vacuum that discharges outdoors also works well.

—Furnace filters. The standard filter on a forced-air furnace doesn't do much to capture household dust. Replace it with a higher-efficiency pleated filter.