Airborne Asbestos (definition of)
Although asbestos fibers can be ingested in drinking water (as was the case in certain communities where water pipes had been manufactured using asbestos-impregnated concrete), it is far more commonly inhaled.
Airborne asbestos can come from any number of sources, including natural ones, as was the recent case in a housing development east of Sacramento, California, when construction activities disturbed deposits of serpentine, from which "white" chrysotile asbestos is made.
Airborne asbestos can also come from the wearing down of automotive brake linings that are manufactured with this substance. However, the most common source of airborne asbestos is from the numerous building materials used over the past century, and are still present in older buildings and sea-going vessels.
Much of the asbestos contained in these locations exists in the form of insulation and pipe lagging. When it is solid, it poses little hazard. However, over time, this asbestos insulation can become brittle and begin to crumble. As this happens, millions of microscopic fibers are released into the air. When asbestos materials are in this state, they are called friable. Most state regulations as well as the EPA define "friable" asbestos as any material that can be crushed using one's hand alone.