Man-Made Vitreous Fibers (MMVF's)
Fibrous Glass, Mineral Wool and Ceramic Fibers are covered in this test procedure. Analysis is performed by a combination of Polarized Light Microscopy (PLM), Transmission Electron Microscopy (TEM) and/or Scanning Electron Microscopy (SEM). The data obtained by this combination can determine the presence of Man-Made Vitreous Fibers (MMVF's) and it can distinguish between the various forms. Many field personnel attempt to use Phase Contrast Microscopy (PCM) and the NIOSH 7400 fiber counting method for MMVF analysis, however, this test was not designed for this purpose and it is not capable of identifying fibrous glass from other fibers.
In cases where MMVF's are suspected of causing indoor air quality (IAQ) issues, it’s important to sample "site standards" for comparison to the MMVF's found in the area samples. By sampling questionable sources such as insulation, ceiling tiles and sound proofing, a forensic style of analysis can reveal the probable origin of the MMVF's isolated from the area samples. When testing an area for MMVF's, it is important to sample the settled dust, which represents the IAQ over an extended period of time. Furthermore, MMVF's tend to settle quickly and may not appear in air monitoring samples resulting in false negatives or under reporting. Settled dust and site standards can show the type, concentration and movement of the MMVF's throughout a building.