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Question from S. J.

[This entry was transferred from the Q&A that was created before this blog existed. There are two questions and one answer.]

The company that services my a/c unit told me that our ducts weren’t sealed properly and it caused dust and mold in the attic to get into the ducts.

The recommendation is that we absolutely have to get the ducts cleaned with high pressure hot water and sanitized with a liquid antibiotic.

I have read some information about ducts cleaning that it was ineffective and dangerous.

Do you have any information you can give on this subject? Any safe alternative to what was recommended? And how would it affect our health if we don’t remove the mold from the ducts?


Debra’s Answer

Having the air ducts cleaned in your central air system is a relatively new service that is being promoted as part of central HVAC maintenance. The EPA has addressed this quite thoroughly on their website “Should You Have the Air Ducts in Your Home Cleaned?”. The site includes:

To evaluate whether or not you need to have your air ducts cleaned, first it’s important to understand how the air flows through your system. Air to be cooled or warmed usually enters the system through a large air intake vent, often placed in the central hallway of the home. The first thing that happens is that the air *goes through a filter*. If the system is working properly, little if any dust or mold will ever go into the ducts. If, however, ducts have not been sealed properly, dust and mold can get into the ducts and may need to be removed.

The EPA concludes most homes probably don’t need air duct cleaning and the cleaning may actually worsen indoor air quality.

Before getting your ducts cleaned, I would recommend getting a second and even third opinion. When we first moved to Florida and needed to get an air conditioner, the evaluations of what we needed and its costs were up to $10,000. Ultimately we found we could repair what we had by replacing part of the system for less than $1000 and it’s been working fine since.

As for the health effects of mold that may be present in your home…mold is ubiqutous–there is always a little mold in the air and on many surfaces. Molds can easily enter your home by circulating through doorways, windows, and, yes, HVAC systems. But mold spores in the air can also land on people and animals, who can bring them indoors as well. Mold only becomes a problem when it can proliferate because of excessive moisture. Unless you have leaky pipes, a roof that leaks during a rainstorm or other sources of excess moisture, you probably don’t have a mold problem in your home. For more on the health effects of mold, see

> EPA Mold Resources
> National Center for Environmental Health: Mold
> American Academy of Pediatrics: Toxic Effects of Indoor Molds

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