Categorizing asbestos materials

In the initial Asbestos NESHAP rule promulgated in 1973, a distinction was made between building materials that would readily release asbestos fibers when damaged or disturbed and those materials that were unlikely to result in significant fiber release. The terms “friable” and “non-friable” were used to make this distinction.

EPA has since determined that, if severely damaged, otherwise non-friable materials can release significant amounts of asbestos fibers.