Air ducts, like any other air conditioning system, require regular cleaning to ensure maximum efficiency. The National Air Duct Cleaners Association (NADCA) recommends cleaning air ducts every three to five years. However, in some environments, the need to clean commercial air ducts is more immediate. In homes where occupants have allergies or asthma, air ducts may need to be cleaned more often. Dust, pollen and other contaminants that accumulate in air ducts can aggravate these conditions.
Therefore, experts recommend cleaning the air ducts every two to three years in these cases for optimal allergy prevention. Pets provide joy and companionship, but they also contribute to more frequent air duct cleaning needs. Pet dander and hair can build up in air ducts over time, contributing to poorer air quality and to possible allergies. If you have pets, consider cleaning the air ducts every two to three years.
You may consider cleaning the air ducts simply because it seems logical that the air ducts will get dirty over time and, therefore, you should clean them from time to time. As long as the cleaning is done properly, there is no evidence to suggest that such cleaning is harmful. The EPA does not recommend that air ducts be cleaned routinely, but only as needed. However, the EPA recommends that if you have an oven, stove or fireplace that burns fuel, that you inspect it for proper operation and be serviced before each heating season to protect against carbon monoxide poisoning. Cases where it may be appropriate to use sealants to encapsulate duct surfaces include repairing damaged fiberglass insulation or combating fire damage inside ducts.
Some service providers may also suggest applying chemical treatments (sealants or other encapsulants) to encapsulate or cover the interior surfaces of air ducts and equipment housings, because they believe that this will control the formation of mold or prevent the release of dirt particles or fibers from the ducts. The EPA does not recommend that air ducts be cleaned except when necessary, due to constant uncertainty about the benefits of duct cleaning in most cases. 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, studies on the effects of duct cleaning do not conclusively demonstrate that the presence of dust and debris in ducts increases levels of particles inside the home.
To find companies that provide duct cleaning services, check the yellow pages on duct cleaning or contact the National Air Duct Cleaners Association (NADCA) at the address and phone number listed in the information section at the end of this guide. Air duct cleaning service providers may tell you that they must apply a chemical biocide inside the ducts to kill bacteria (germs) and fungi (mold) and prevent future biological growth. A careless or inadequately trained service provider can damage ducts or the heating and cooling system, which could increase heating and air conditioning costs or force you to perform difficult and costly repairs or replacements. Knowledge about cleaning air ducts is in its early stages, so a general recommendation cannot be given as to whether you should clean the air ducts in your home.
If no one in your household has allergies or unexplained symptoms or illnesses and if, after a visual inspection of the interior of the ducts, you see no sign that the air ducts are contaminated with large deposits of dust or mold (with no musty smell or visible mold growth), cleaning the air ducts may not be necessary. This is because much of the dirt that can accumulate inside air ducts adheres to duct surfaces and doesn't necessarily enter the living space. However, many modern residential air duct systems are built with fiberglass or sheet metal ducts lined inside with a fiberglass coating. Regardless of whether or not you decide to clean your home's air ducts, preventing water and dirt from entering the system is the most effective way to prevent pollution (see How to Prevent Duct Contamination).
