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Asbestos Asbestos
Evaluating Exposure

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Asbestos - Construction page.
Determinations of employee exposure shall be made from breathing zone air samples that are representative of the 8-hour TWA and 30-minute short-term exposures of each employee.

Medical surveillance

Medical surveillance guidance is provided in the appendices to the OSHA Standards:
Exposure monitoring

Exposure monitoring samples must be analyzed by Phase Contrast Microscopy (PCM) for OSHA purposes. PCM methods accurately assess fiber exposure levels, but PCM can not differentiate between asbestos and non-asbestos fibers. Transmission Electron Microscopy (TEM) methods may be used to identify fibers, but may not be used to quantify air concentrations for occupational exposure.
  • OSHA (Sampling) Reference Method
  • Asbestos in Air. OSHA Analytical Method ID-160, (1997).
  • Detailed procedure for asbestos sampling and analysis
  • NIOSH Manual of Analytical Methods (NMAM). National Institute for Occupational Safety and Health (NIOSH), (1994, August). Includes asbestos methods 7400 and 7402. Method No. 7400 is a PCM procedure, equivalent to the OSHA methods. Method No. 7402 uses TEM to identify fibers (OSHA will accept this TEM procedure, as it uses PCM to determine exposure). Includes indices to 3rd and 4th edition.
    • Asbestos fibers by TEM. NIOSH Method No. 7402, (1994, August), 40 KB PDF, 7 pages.
Bulk sample analysis

Bulk sample analysis should be done by Polarized Light Microscopy (PLM). Bulk analysis results will likely apply to both OSHA and EPA regulations.
  • Polarized Light Microscopy of Asbestos. OSHA Method ID-191 (1992). Ddescribes the collection and analysis of asbestos bulk materials by light microscopy techniques including phase-polar illumination and central-stop dispersion microscopy.
  • Polarized Light Microscopy of Asbestos
    • 1910.1001, Asbestos. OSHA Standard. 
      • Appendix J, Polarized light microscopy of asbestos; Non-mandatory
    • 1915.1001, Asbestos. OSHA Standard. 
      • Appendix K, Polarized light microscopy of asbestos; Non-mandatory analytical methods
  • National Institute for Occupational Safety and Health (NIOSH) has published two methods for the determination of asbestos in bulk materials.
    • Asbestos, Chrysotile by XRD. NIOSH Method No. 9000, (1994, August), 44 KB PDF, 6 pages.
    • Asbestos (bulk) by PLM. NIOSH Method No. 9002, (1994, August), 176 KB PDF, 9 pages.
  • Directory of Accredited Laboratories. National Voluntary Laboratory Accreditation Program (NVLAP), (2008). Includes online searchable directory. This accreditation is required for analyses being performed in compliance with AHERA regulations.
  • Sampling and Analysis of Multi-Layered Materials
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  Evaluating Exposure
Content Reviewed 08/19/2008

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Page last updated: 08/19/2008