January 30, 2019
Today, when many of us are eating clean and trying to live green, we feel very virtuous about getting rid of the “gunk” in our bodies and our lives. Therefore, when a company calls and offers to eliminate the accumulated dust, soot, pollen, mold, and debris in our residential air ducts, we may jump at the deal as a way to banish indoor pollution (and address secondary issues such as allergies, headaches, fatigue, and respiratory illnesses).
After all, if our ducts are clean, all that air flowing out of those vents should come out clean, too, right? Well, actually, no, according to a recent report by The Washington Post.
Even if your ducts truly are dirty, cleaning them probably won’t provide any measurable benefits. In fact, the little independent research performed on duct cleaning indicates that the process stirs up so much dust that it creates a bigger problem than it solves.
Indeed, a study conducted by U.S. Environmental Protection Agency measured dust levels and HVAC system efficiency in test homes during a one-week period during the cooling season and found duct cleaning did not significantly improve dust levels or system performance.
Based on that report and other independent research, the EPA’s official advisory on duct cleaning concludes: “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. This is because much of the dirt in air ducts adheres to duct surfaces and does not necessarily enter the living space….Moreover, there is no evidence that a light amount of household dust or other particulate matter in air ducts poses any risk to your health.”
The fact is, the Post says, that dust that settles in your ventilation system generally stays where it is—unlikely to become airborne unless disturbed. Under most circumstances, the dust is inert and harmless, and stirring it up with cleaning equipment actually creates bigger issues.
The Canada Mortgage and Housing Corporation (CMHC), a government agency, conducted a similar study in the 1990s. After testing 33 homes in Montreal before and after duct cleaning, the researchers found that there was no significant improvement in air quality—and that duct cleaning, alone, did not improve airflow or energy efficiency.
In some cases, measured particle levels actually increased immediately after a cleaning. In other cases, particle levels decreased immediately after cleaning but returned to previous levels within weeks.
Like the EPA, the CMHC concluded that duct cleaning is unnecessary: “Ideally, the inside surface will be shiny and bright after cleaning. Duct cleaning may be justifiable to you personally for that very reason: you may not want to have your house air circulated through a duct passage that is not as clean as the rest of the house. However, duct cleaning will not usually change the quality of the air you breathe, nor will it significantly affect air flows or heating costs.”
Instead, experts recommend frequently changing air filters as the best way to keep dust, allergens, and other particles out of your home. With a newly installed system, or a system in a home you’ve just moved into, check your filter monthly to determine how quickly it gets dirty at different times of the year. Most should be replaced every two or three months.
In general, consider duct cleaning only in response to specific, identifiable problems. For example, the EPA suggests having air ducts cleaned if there is visible evidence of:
- Substantial mold growth,
- Infestation of insects or rodents, or
- Substantial deposits of dust or debris (if registers were not sealed during a renovation project, for example).
If anyone in your household has specific health concerns, such as allergies or asthma, consult your physician first. It’s important to identify the problem so your doctor can suggest alternatives to duct cleaning. Start by identifying whether your ducts are part of the problem (they probably aren’t) and whether getting them cleaned will help (it probably won’t).
Finally, if you suspect a mold problem—either because of visible growth or a musty smell consistently coming from supply vents — the experts generally recommend tracking down and eliminating moisture problem, itself, whether it originates under a sink or part of a heating and cooling system.
Research contact: @washingtonpost