In the United States there are seven (7) published sources of occupational exposure limits (OELs)1. This list of sources does not include exposure limits that are recommended by individual manufacturers which may be included on material safety data sheets. The published sources include:

  1. Occupational Safety and Health Administration (OSHA) - Permissible Exposure Limits (PELs)

  2. American Conference of Governmental Industrial Hygienists (ACGIH) - Threshold Limit Values (TLVs)

  3. American Industrial Hygiene Association (AIHA) - Emergency Response Planning Guidelines (ERPGs)

  4. American Industrial Hygiene Association (AIHA) - Workplace Environmental Exposure Level Guides (WEELs)

  5. American National Standards Institute (ANSI)

  6. Mine Safety and Health Administration (MSHA) - Permissible Exposure Limits (PELs)

  7. National Institute of Occupational Safety and Health (NIOSH) - Recommended Exposure Limits (RELs)

Companies are faced with the decision of which source or sources of OELs they will use. As occupational safety and health professionals we may be called upon to decide or provide input into the decision. There are many factors to be considered in making this decision. Before looking at the variables involved, it helps to understand each of the sources. Each is summarized below.

Occupational Safety and Health Administration (OSHA) - Permissible Exposure Limits (PELs).

The OSHA limits are mentioned first because OSHA Standards are the primary governing source for occupational exposure in the United States. In other words, they are legally enforceable exposure limits. The OSHA PELs are published in the OSHA standards, Subpart Z - Toxic and Hazardous Substances. The PELs are updated individually according to a process established in OSHA regulations. Anyone can request OSHA consider an update to or an addition of a PEL. The OSHA standards are available on the internet and through various printing sources and are not copyrighted. The PELs consist of any of the following possibilities:

  1. 8 hour time weighted average - PEL-TWA;

  2. 15 minute short term exposure limit - STEL;

  3. Ceiling or maximum exposure; - C

  4. Action limits, usually in individual chemical standards, triggering specific actions; and

  5. Excursion limits or other maximum exposure limit expressed over some period of time.

American Conference of Governmental Industrial Hygienists (ACGIH) - Threshold Limit Values (TLVs)®

The TLVs are published by ACGIH as recommendations or guidelines. They are not legally enforceable. The TLV list of exposure limits is a copyrighted source and must be purchased from ACGIH. The exposure limits are published in a handbook format as a list with use information preceding the list. ACGIH also publishes a complete set of information containing a summary of information used to establish individual exposure limit values - referred to as "Documentation of TLVs". The TLVs are published annually. A peer review process updates the TLVs. The TLV Committee members as well as consultants may nominate chemicals for consideration for update or newly established limits.

Keywords:
exposure assessment, american national standard institute, OEL, recommendation, limit value, Institute, hazard, US government, selection, united states
Subjects:
Health, Safety, Exposure assessment
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2002. American Society of Safety Engineers
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