Air ducts are the pathways that deliver the indoor air you breathe. Under certain conditions, they make a perfect home for mold, pests and dust particles that could be blown into your home’s living spaces and trigger your allergies. Because of this, you may think that you should have your air ducts cleaned regularly. But read on.

Despite years of research, there is no conclusive evidencethat particle levels in homes increase even when air ducts are dirty. Most of the dirt and dust that collects in air ducts adheres to surfaces and is not blown out into the living environment. In fact, pollutants from indoor sources such as cooking and cleaning, as well as outdoor pollutants that are inside the home,are much more significant sources of contaminants. And in some cases, cleaning air ducts is not only unnecessary; it’s downright dangerous.

Some air ducts are hazardous to clean

Asbestos:Ductwork that is made of asbestos is especially hazardous, and should not be cleaned under normal circumstances. The asbestos can deteriorate and the fibers can be blown into the house, and cleaning can expose both the cleaners and the home’s occupants to airborne fibers. Asbestos air ducts can be safely removed only by a qualified asbestos abatement contractor and then replaced with new non-hazardous ductwork. Air ducts that are lined or wrapped with asbestos should also be removed, or at least encapsulated, whenever possible.

Fiberglass:Fiberglass air duct liner and air duct board also presents a problem and must be cleaned according to strict standards developed by the National Air Duct Cleaning Association. Vacuuming with a special HEPA filter, air washing and power brushing are considered acceptable techniques when performed by a qualified expert.

When you should consider having your air ducts cleaned

Even when hazardous ductwork material is not an issue, air duct cleaning should only be undertaken as a last resort, and only after thorough evaluation by a professional. Certain conditions may warrant consideration of air duct cleaning:

1. There is visible moldinside your air ducts or on other components of your heating and cooling system.
2. Your air ducts are infestedwith rodents, insects or other pests.
3. Your air ducts are cloggedwith dust and debris or significant levels of particles are being released into the home from the supply registers.

Choosing an air duct cleaner

If you are considering air duct cleaning for one of the reasons mentioned above, you may want to consult with the company that services your heating and cooling system for advice. They can inspect your system and also recommend an air duct cleaning company. You should also consider contacting the National Air Duct Cleaners Association at www.nadca.com to find a qualified air duct cleaner near you.

It is a wise idea to get estimates from three different providers, and ask them to show you the contamination they have detected and plan to clean. Only allow air duct cleaners to apply biocides or other chemicals if you fully understand what they are applying, why they are applying it, and what possible hazards the chemicals may present.

Prevention is the best strategy

Whether or not you decide to have your air ducts cleaned, it is always important to prevent water and dirt from entering the air duct system in the first place.

Moisture:It’s critical to promptly repair any leaks or water damage in your heating and cooling system. Check condensation pans for proper drainage. Also, make sure air ducts are properly sealed and insulated to prevent water condensation.

Dirt:Protect your heating and cooling system by using a high-efficiency air filter. The best choice is the IQAir Perfect 16 air filtration system, which removes more than 95% of all particles (0.3 microns or larger) and at least 85% of all ultrafine particles before they can reach your system coils.

Home vacuuming:Regular vacuuming of your home with a high-efficiency HEPA vacuum can also help reduce the amount of dust in your air ducts and throughout your home.

For more information on how to keep your air ducts clean, visit www.epa.gov.