Further, the Washington Post even wrote this article on the subject more recently (in 2019) citing a lot of the same evidence that cleaning your air ducts has very little, if any, meaningful effect on your home’s air quality under most normal situations.

To summarize the 2 decades worth of studies performed by various US health organizations that studied the effects of cleaning a typical home’s air ducts, the DOHS released this fact sheet in 2015 that can be summarized as follows: the recorded level of air pollutants and contaminants (dust) was widely varied in homes that were tested both before and after the air ducts were cleaned, but most importantly, “even when duct cleaning was extremely efficient at removing contaminants within ducts, the effectiveness of reducing indoor air pollutants was highly variable, and, in many cases, post-cleaning levels of contaminants were higher than pre-cleaning levels.”

Does cleaning air ducts make the system more efficient (and save money)?

Claims purporting that cleaning your air ducts will make the system more efficient and thus lower your energy bill are still unfounded at this time, according to the studies performed by those like the EPA and DOHS.  The reality is that a home’s air condition system is inherently inefficient, and will suffer many “energy loses” that are not in your control and not attributable to dust in your air ducts. 

The recommendation by the EPA, for instance, is to focus on maintaining the running components of your air conditioning system:

• blower / motor of the system
• replacing air filters
• cleaning coils
• yearly maintenance checks

If you want to boost your system’s efficiency, the first place to look would be leaky ducts!  That is, leaks at air duct connections or at a specific section of damaged air duct.  Properly sealing and correcting large inefficiencies like this is really where you will find noticeable energy savings (lower energy bills) and a better flowing system, if you notice certain rooms in your home or either too hot or too cold when the system is running.

Cleaning your air ducts will reportedly have very minimal or negligible effect according to the collective studies done by government health organizations; meaning, you really won’t see any changes to your energy bill.  You should be skeptical of companies that report huge energy savings from cleaner air ducts, because that is not based on any evidence.  

However, it is worth mentioning that cleaning the blower / motor or fan blades could actually have some positive effect on your air conditioning system efficiency, but nothing as significant as patching / sealing leaks present in the system.

Special circumstances when Cleaning Air Ducts is Recommended

The Division of Occupational Health and Safety (DOHS) and the Environmental Protection Agency (EPA) all promote a few situations where it is recommended (and necessary) to clean or even replace a home’s air ducts. 

Namely:

• If there is any mold or other growth found inside the ducts (Note: mold needs to be confirmed by a specialist or lab test, which may only cost about $50.  What looks like mold, may not be)
• Water damage to the ducts or to insulation surrounding the ducts
  • FYI: mold found in insulation cannot be properly cleaned, so insulation replacement is recommended.
• Foul smells in the ducts themselves
• Backup in your ducts from debris or an infestation
• Noticeable dust or debris coming from your air distribution vents

If any of the above occur, generally, you have issues beyond the limit of your air conditioning system, and the source of your issues (mold, infestation, water, or bad smells) should be fixed prior to cleaning or replacing your air ducts.

EPA certified or approved

The EPA’s website directly spells out that they do not certify, approve, or endorse any duct cleaning companies or duct cleaning standards at all.  If an air duct cleaning company says that they are “EPA certified” or “EPA approved,” they are making a bold misstatement and you should be very skeptical of working with them.

Although the EPA does not certify duct cleaning procedures, you may come across “EPA-registered biocides,” which is a product that can be sprayed on the inside lining of your air ducts to prevent biological growth. 

It is a legal requirement that all biocides be registered with the EPA, so do not confuse being EPA-registered with some sort of EPA endorsement of the biocide.  Even the EPA states on their website that there is much controversy over using biocides in home air ducts, and there is little research on the potential positive and negative effects.  Because of this, the DOHS simply recommends avoiding biocides all-together.

Routine Cleaning is still your best tool for keeping air ducts clean

Studies done by the EPA show that there is no evidence linking dirty air ducts to higher amounts of dust and particulates in your home.  Furthermore, they also could not find any evidence that a light or typical amount of dust in your air ducts poses any health risk.

The means that generally speaking, cleaning air ducts is not necessary as part of your typical, “routine” home cleaning.  It is reserved for more special situations that would be recommended on a case-by-case basis.

The best way to keeping your home and your air ducts clean is:

1. Maintain routine cleaning (vacuuming, dusting, and replacing home air filters). 
2. Keep sources of contamination away from your air intake vents. 
   • You might notice how there are no intake vents in your home bathrooms (only vents to outside).  There’s a reason for that, and it’s because the air could be contaminated.

Takeaway

Clean your home regularly.  Hire someone to check and maintain the working units of your system on a yearly basis, and even consider having a professional identify points of failure where your air ducts may be leaking, but specifically cleaning your air ducts is not recommended under normal circumstances and is only something that should be performed in special situations by a professional team.

To see the full list of the EPA’s recommendations for identifying mold, dealing with contractors, and ultimately, choosing weather to clean your air ducts or not, see their article on “Should You Have the Air Ducts in Your Home Cleaned.”