Missoula Technology and Development Center Facilities Toolbox: Hazardous Substances in Buildings
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What's the difference between friable and non-friable asbestos?

First, you need to know that although some products are mostly asbestos (like older brake pads), it is more common for asbestos to be combined with other components into an asbestos containing material (ACM).  Something is an ACM if it contains more than one percent asbestos, as determined by a testing method called Polarized Light Microscopy.

When dry, an ACM is considered friable if it can be crumbled, pulverized, or reduced to powder by hand pressure.  If it can't, it's considered non-friable ACM.  It's possible for non-friable ACM to become friable when subjected to unusual conditions, such as demolishing a building or removing an ACM that has been glued into place.

Non-friable ACM is divided into two categories.  Category I non-friable ACMs are asbestos-containing resilient floor coverings (like vinyl asbestos tile), asphalt roofing products, packings, and gaskets.  These materials rarely become friable because the asbestos is locked securely into the material.  All other non-friable ACMs are considered category II non-friable ACM.  Category II non-friable ACMs are more likely to become friable because they are not as resistant to crushing or pulverizing.

The term “asbestos” doesn't refer to one particular mineral.  Asbestos is a generic name given to the fibrous variety of six naturally occurring minerals that have common characteristics.  Asbestos is made up of bundles composed of extremely long, thin fibers that can be easily separated from one another.  Asbestos minerals won't burn.  They can be woven and possess high tensile strength, flexibility, and resistance to chemicals, heat, and electricity.  The minerals that can crystallize as asbestos belong to two groups: serpentine (chrysotile) and amphibole (crocidolite, amosite, anthophyllite, tremolite, and actinolite).

Breathing asbestos fibers can lead to an increased risk of asbestosis, lung cancer, and mesothelioma.  The symptoms of these diseases don't usually appear for 20 to 30 years after the first exposure to asbestos.  Asbestosis is a noncancerous lung disease related to scarring of the lungs.  This disease occurs in people heavily exposed to asbestos in the workplace and to people who live with asbestos workers, because the workers bring asbestos fibers home on their clothing, skin, and tools.  Lung cancer is a relatively common form of cancer.  Cigarette smoking significantly increases the risk of lung cancer for people exposed to asbestos.  Mesothelioma is a rare cancer of the membranes lining the lungs, chest, and abdominal cavity that is caused almost exclusively by occupational asbestos exposure.

You can learn more about the different types of asbestos, their uses, and health effects from the Environmental Protection Agency, Centers for Disease Control, and University of Montana.


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