November 20, 1990: Specific Method Stipulated for Examination of Asbestos

NESHAP regulations require use of the transmission electron microscopy (TEM) method to determine whether asbestos-derived wastes are asbestos free: “Transmission electron microscopy (TEM) shall be used to analyze the output material for the presence of asbestos.” In order to be considered “asbestos-free,” TEM results must indicate that the waste contains no asbestos. [US Code, Vol. 40, sec. 61.155] The TEM method is far superior to polarized light microscopy (PLM) testing, a less expensive method that is often used to test for the presence of asbestos in bulk building material. The PLM method is limited by relatively weak magnification (100-400x) and it is sometimes unable to distinguish asbestos material from other materials like tar and petroleum binding components that may also be present in the building material. As a result of these deficiencies, the PLM method cannot reliably detect asbestos at concentrations of less than 1 percent and it is incapable of detecting asbestos fibers that are less than .25 micrometers in width. [Jenkins, 3/11/2002 ] TEM uses 20,000X or greater magnifications as well as powerful chemical (EDXA) and mineralogical (SAEDP) tools. Not only can TEM differentiate asbestos from non-asbestos fibers, but it can also distinguish one species of asbestos from another. [International Asbestos Testing Lab, 1/12/2006]