CARB DEFINITIONS OF ASBESTOS

The California Air Resources Board (CARB) is in the process of re-writing regulations designed to control airborne asbestos emissions from road grading, quarrying, or other earth moving operations. As part of this re-write, CARB has proposed a new definition of “asbestos” that incorporates nearly all amphibole minerals. Raw materials are mined throughout the western United States in a variety of geological settings, almost all of which may incorporate serpentine or amphibole minerals. Under the correct conditions, serpentine and amphibole minerals will grow (or form) as asbestos fibers (chrysotile, tremolite asbestos, actinolite asbestos, etc.). However, these occurrences are rare and the vast majority of these minerals are not asbestos. Unfortunately, the amphibole minerals will break (or cleave) as elongated particles when crushed or pulverized. CARB’s definition makes no distinction between the various morphologies of amphibole minerals and creates confusion in the analytical community. This definition and resulting analytical confusion needlessly puts nearly all raw materials operations in the Western US at risk of being classified as “asbestos mines”, imputing liability where none is deserved. This paper discusses the various definitions of asbestos and the implications of these defintions.