Is floor tile considered asbestos-containing material (ACM) under the Asbestos Hazard Emergency Response Act (AHERA) if there are contradictory results between polarized-light microscopy (PLM) and transmission electron microscopy?

For its inspection and assessment purposes, the local education agency (LEA) must first rely upon the results analyzed using the 1992 Interim PLM Method found at Appendix A to Subpart E in 40 CFR part 763, unless, it chooses to alternatively rely upon the improved “Test Method for the Determination of Asbestos in Bulk Building Materials (EPA/600/R-93/116, July 1993)” which employs TEM analysis. The Environmental Protection Agency (EPA) recommends use of the updated method of TEM analysis to determine whether or not floor tiles are ACM. TEM analysis is able to yield more precise analytical results, especially at low asbestos concentrations, and helps to rule-out false negatives when performing analysis on floor tile. If either TEM or PLM analysis yields a result that the material contains greater than 1 percent asbestos, then the material must be considered ACM.