What material is considered the most friable concerning asbestos?

Sprayed-on fireproofing is considered the most friable material concerning asbestos because it is typically applied as a wet mixture that dries into a brittle, easily breakable form. This type of asbestos-containing material can release fibers into the air with minimal disturbance, particularly when subjected to vibrations, impacts, or environmental degradation. The friability of a material indicates how easily it can crumble and release asbestos fibers, which poses significant health risks due to inhalation.

In contrast, insulation board, while it can also contain asbestos, tends to be denser and more stable than sprayed-on fireproofing, making it less likely to release fibers if left undisturbed. Stucco material, depending on its composition, can vary in friability but generally is not as prone to releasing asbestos fibers as sprayed-on fireproofing. Floor tiles are typically considered non-friable because they are solid and not easily broken into smaller pieces, which limits the potential for fiber release under normal circumstances. Thus, the properties of sprayed-on fireproofing cement its status as the most friable asbestos material.