Which statement best describes the limitations of PCM in asbestos analysis?

The statement that best describes the limitations of Polarized Light Microscopy (PCM) in asbestos analysis is that it cannot identify fiber type or distinguish smaller fibers. PCM is a widely used technique for the identification of asbestos fibers, but it has significant limitations in its accuracy and breadth of analysis.

PCM is primarily effective for counting fibers and determining whether asbestos is present in a sample. However, it cannot effectively differentiate various types of asbestos fibers, such as chrysotile, amosite, or crocidolite, due to the inability to distinguish fibers that are smaller than 0.5 micrometers in diameter. Many asbestos fibers fall below this threshold, limiting the utility of PCM for comprehensive asbestos characterization.

By understanding these limitations, practitioners can make informed decisions about the methodology used for asbestos analysis. While PCM can provide important data about the presence of asbestos fibers, confirmation of fiber type may require more advanced techniques, such as Transmission Electron Microscopy (TEM), which can provide more detailed fiber identification.