Evaluating and Controlling Exposure

Evaluating Exposure

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 following 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.

Analytical Methods


OSHA has developed and validated methods for use by the Salt Lake Technical Center (SLTC) laboratory. The following method has been adopted by many laboratories for the analysis of chemical compounds. Exposures should be evaluated with standard total dust sampling techniques for comparison to the OSHA permissible exposure limits (PEL).

National Institute for Occupational Safety and Health (NIOSH)

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.


Controlling Exposure

Controlling the exposure to asbestos can be done through engineering controls, administrative actions, and personal protective equipment (PPE). Engineering controls include such things as isolating the source and using ventilation systems. Administrative actions include limiting the workers exposure time and providing showers. Personal protective equipment include wearing the proper respiratory protection and clothing. The following resources contain information to help control asbestos exposures.

  • NIOSH Pocket Guide to Chemical Hazards. U.S. Department of Health and Human Services (DHHS), National Institute for Occupational Safety and Health (NIOSH) Publication No. 2005-149, (September 2007). Provides a physical description, exposure limits, measurement method, personal protection and sanitation, first aid, respirator recommendations, exposure routes, symptoms, target organs, and cancer sites.
  • Occupational Health Guidelines for Chemical Hazards. U.S. Department of Health and Human Services (DHHS), National Institute for Occupational Safety and Health (NIOSH) Publication No. 81-123, (January 1981). Contains information on identification, physical and chemical properties, health hazards, exposure limits, exposure sources and control methods, monitoring, personal hygiene, storage, spills and leaks, and personal protective equipment


Precautions to prevent exposure to asbestos in friction products (brakes and clutches).


Operations and maintenance (O&M) practices are used to control hazards of asbestos.


  • Applicability Determination Index (ADI). Environmental Protection Agency (EPA). Enables the user to query the database of National Emissions Standards for Hazardous Air Pollutants (NESHAP) which includes "regulatory interpretations". Enter keyword "Asbestos".
  • Protect Your Family. Environmental Protection Agency (EPA). Provides EPA guidance for home owners and their families.