Air ducts, like any other air conditioning system, require regular maintenance to ensure optimal performance. The National Air Duct Cleaners Association (NADCA) recommends cleaning air ducts every three to five years. However, in certain environments, the need for commercial air ducts to be cleaned is more urgent. It is sensible to clean air ducts periodically as they can become dirty over time.
As long as the cleaning is done correctly, there is no evidence that it is harmful. The EPA does not suggest that air ducts be cleaned routinely, but only when necessary. They do advise that if you have an oven, stove, or chimney that burns fuel, they should be inspected and serviced before each heating season to protect against carbon monoxide poisoning. A common statement from some HVAC companies is that a home's HVAC ducts should be cleaned at least once every three to five years to guarantee that hair, dust, and dirt don't affect air quality in the home and cause health issues. Studies on the effects of duct cleaning do not conclusively demonstrate that the presence of dust and dirt in ducts increases the levels of particles inside the house.
You may have seen an advertisement, received a coupon in the mail, or been contacted directly by a company offering to clean the air ducts in your home as a way to improve indoor air quality. It's important to note that dirty air ducts are just one of many potential sources of particulate matter in homes. Most organizations dealing with pipeline cleaning, including the EPA, NADCA, NAIMA, and the National Association of Sheet Metal and Air Conditioning Contractors (SMACNA), do not currently recommend the routine use of sealants to encapsulate contaminants in any type of duct. Manufacturers of products marketed to coat and encapsulate duct surfaces claim that these sealants prevent dust and dirt particles inside air ducts from being released into the air. In addition, the resistance of sealants to deterioration over time, which could add particles to the air in the ducts, has not yet been evaluated. However, NADCA adds that homeowners should inspect their air ducts once a year to check their condition.
Since the conditions in every home are different, it's impossible to generalize about whether cleaning the air ducts in your home would be beneficial or not. If no one in your household has allergies or unexplained symptoms or illnesses, and if after a visual inspection of the inside of the ducts you don't see any signs that they are contaminated with large deposits of dust or mold (there is no musty smell or visible mold growth), then cleaning the air ducts is probably not necessary. In addition, there is no evidence that a small amount of household dust or other particles in air ducts poses a risk to health. Contaminants that enter the home from both outdoor and indoor activities such as cooking, cleaning, smoking or simply moving around can cause greater exposure to contaminants than dirty air ducts. If you haven't lived there before you don't know what's in the air ducts and how well they were treated by previous owners. They may also propose applying a sealant to prevent dust and dirt particles from being released into the air or sealing any air leaks. Overall, it is recommended that homeowners inspect their air ducts annually for signs of contamination and clean them when necessary.
While there is no definitive answer as to how often you should clean your air ducts, following NADCA's recommendation of every three to five years is a good starting point. If you notice any signs of contamination such as musty odors or visible mold growth then it may be time for a professional cleaning.
