Many people wonder whether they should clean their home’s air ducts every year. The answer varies from home to home.

Air duct cleaning companies, from a business perspective, may recommend regular cleaning to prevent or alleviate allergies or asthma. In reality, there are many factors that contribute to poor indoor air quality and related health problems. While air duct cleaning may sometimes be helpful, it is not generally considered a comprehensive solution for improving indoor air quality.

The U.S. Environmental Protection Agency (EPA) does not recommend routine cleaning of air ducts. Cleaning may be appropriate when there is substantial visible mold growth inside hard-surface ducts, when the ducts are infested with insects or rodents, or when substantial amounts of dust and debris have accumulated and are actually being released into the home. The EPA notes that there is currently no evidence that simply having dirty air ducts increases the amount of dust in a home or that duct cleaning prevents health problems.

Residents may have difficulty determining the condition of their ductwork because much of the system is inaccessible. However, ordinary household dust should not be assumed to be accumulating in ducts in quantities that make duct cleaning necessary. Dust mites and their waste can contribute to allergies and asthma, but they primarily live in household furnishings such as bedding, carpets, and upholstered furniture rather than inside air ducts.

Many people mistakenly believe that indoor dust is routinely distributed throughout the home by the air ducts. In reality, dust enters and accumulates in homes from many sources, including outdoor air, people, pets, fabrics, and household activities. Ducts can accumulate dust and debris, but there is insufficient evidence that normal amounts of dust inside ducts are routinely redistributed throughout a home.

When scheduling air duct cleaning, consumers should be cautious about companies that propose spraying fragrances, chemical treatments, or other substances into the ductwork without a specific need. Such products can introduce additional chemicals into indoor air. If mold is identified, the underlying moisture problem should also be addressed; simply treating the ducts without eliminating the source of moisture will not solve the problem.

Ozone should not be used as a routine treatment for air ducts or indoor air. Ozone is a lung irritant, and the EPA does not recommend ozone generators for improving indoor air quality in occupied spaces.

作者：Michael Chiu，MWS，CI
Previously published in Ming Pao Daily News – Updated and Revised in 2026