Definition
Recommendation for certified asbestos inspector sampling
See also:
ACM (Asbestos-Containing Material)
ACM (asbestos-containing material) is any material with more than 1% asbestos by weight. At peak use, ACMs appeared in over 3,000 different products: insulation, fireproofing materials, roofing, flooring, and cement products. Buildings must be surveyed for ACMs before renovation or demolition, and any found must be managed or removed to protect occupants and workers.
Asbestos
A commercial and regulatory label, not a mineralogical term, for a group of six naturally occurring fibrous silicate minerals of diverse geological origins, each extracted from different types of rock. The English name comes from the ancient Greek ásbestos (ἄσβεστος, "inextinguishable"), while Romance languages use "amianto" / "amiante", from Greek amÃantos (ἀμίαντος, "incorruptible", "immaculate"); both names express the ancient awe at a material fire could not destroy. The six regulated minerals fall into two families: serpentine (chrysotile) and amphibole (crocidolite, amosite, anthophyllite, tremolite, actinolite). Asbestos was widely used in construction and manufacturing due to its heat resistance, tensile strength and insulating properties, with roughly 3,000 industrial applications at peak use in the 1970s. When disturbed, it releases microscopic fibres that lodge permanently in lung tissue, causing mesothelioma, lung cancer and asbestosis. All forms are classified as Group 1 human carcinogens by the IARC, and more than 70 countries have banned it.
PCM (Phase Contrast Microscopy)
A method of analyzing air samples to count asbestos fibers using a phase contrast microscope. PCM is the standard method for measuring airborne asbestos concentrations and verifying compliance with exposure limits. However, PCM cannot identify fiber type and counts all fibers meeting size criteria, potentially overestimating asbestos fiber concentrations.
PLM (Polarized Light Microscopy)
A technique for identifying asbestos in bulk material samples using polarized light and optical properties. PLM is the standard method for analyzing building materials suspected of containing asbestos. The method can identify asbestos type and estimate concentration. Samples are typically collected during surveys and analyzed in accredited laboratories.