Ducts may be made of asbestos material or be wrapped with asbestos material. Determining how safe asbestos ducting depends on several factors.
ACM stands for Asbestos Containing Material ( Material containing 1% or more of asbestos)
Asbestos ducts; basically two types
1. Metal ducts wrapped with ACM
2. Ducts that are made of ACM’s
Metal ducts wrapped with ACM
If metal ducts are wrapped with asbestos insulation on the outer surfaces of the metal duct, where it is not exposed to an airstream in the ducts, then there is less opportunity for contamination of the circulating air. From the mid-1950s to the early 1970’s it was common to wrap metal ducts with a cardboard like insulating material that contained some asbestos.
Ducts made of ACM’s
Ducts which are made of ACM are much less common than metal ducts wrapped with ACMs. If a duct is made of ACMs and it is punctured or damaged, then asbestos fibers may be circulating in the air. If this is the case, it should be reviewed and corrected.
Is there a health risk?
The answer to this depends on what type of ducts you have and the condition of the ducts and duct material. Generally, there are no building codes that require a buyer to remove asbestos ducting.
The first thing to check is whether the duct is composed of asbestos materials or just insulated with asbestos materials.
Metal ducts wrapped with asbestos materials
If the airstream in this type of ducts isn’t exposed to the asbestos material and there is little chance of exposure or contamination, then many contractors will be comfortable leaving the ducts as is.
Ducts made of ACM
These types of ducts are not as common as the other types of ducts. Some of the ACM ducts will have a foil interior to separate the airflow from the asbestos material. If ducts made of ACM are in good shape, un-damaged and there are no loose fibers, then the risk is less than if the ducts are damaged and loose fibers are exposed to the air stream. Damaged ducts should be properly repaired or replaced.
The EPA and consulting with a certified asbestos inspector are good places to obtain additional material and information.
Even if asbestos is in your home, it is often not considered a serious problem. The mere presence of asbestos in a home or a building may not hazardous. The danger is that asbestos materials may become damaged over time. Damaged asbestos may release asbestos fibers and become a health hazard. For more information, see:
Home owners can do limited maintenance items themselves. HVAC contractors and asbestos abatement companies should be consulted for more complex work or modification. Any disposal of asbestos materials require special handling, therefore qualified professions should handle this task.