Occupational exposure limit

An occupational exposure limit is an upper limit on the acceptable concentration of a hazardous substance in workplace air for a particular material or class of materials. It is typically set by competent national authorities and enforced by legislation to protect occupational safety and health. It is an important tool in risk assessment and in the management of activities involving handling of dangerous substances.[1] There are many dangerous substances for which there are no formal occupational exposure limits. In these cases, hazard banding or control banding strategies can be used to ensure safe handling.

Simple representation of exposure risk assessment and management hierarchy based on available information

Occupational Exposure Limits (OELs) have been established for airborne workplace chemicals by multiple regulatory and authoritative organizations around the world for well over 60 years now. With the changing regulatory arena, shifting centers of manufacturing growth, and the move towards a more global view on occupational hygiene issues, it is important for the Occupational Hygiene profession to understand the current and growing issues impacting the continued viability of OEL’s in our professional practice.[2]

Although peer-reviewed health-based OELs are preferred for establishing safe levels of exposure or for implementing adequate controls to provide worker protection, the lack of publicly available OELs have led to other sources of safe levels to protect workers. Industrial or Occupational Hygienists are often on the front line of anticipating and recognizing the hazards of chemical exposure for workers, and must assess the risk of exposure through the use of OELs so that proper control strategies can be implemented to keep workers below the OEL values. In the absence of OELs however, there are a variety of tools that can and should be used to assess exposure potential of workers. The "Hierarchy of OELs" provides a continuum of occupational exposure limit values that allow assessment of the risk of exposure in order to apply adequate controls.[3]

Hierarchy of occupational exposure limits (OELs)
Illustration of statistical output from IHSTAT using air sampling data

Personal air sampling is routinely conducted on workers to determine whether exposures are acceptable or unacceptable. These samples are collected and analyzed using validated sampling and analytical methods. These methods are available from OSHA Technical Manual and NIOSH Manual of Analytical Methods [4] Statistical tools are available to assess exposure monitoring data against OELs. The statistical tools are typically free but do require some previous knowledge with statistical concepts. A popular exposure data statistical tool called "IH STAT" is available from AIHA (American Industrial Hygiene Association). IHSTAT has 14 languages including English and is available for free.[5]

Methods for performing occupational exposure assessments can be found in "A Strategy for Assessing and Managing Occupational Exposures, Third Edition Edited by Joselito S. Ignacio and William H. Bullock".[6]


  1. European Agency for Safety and Health at Work. "Occupational Exposure Limits". Retrieved 2008-04-24.
  2. IOHA. "International OEL Issues and Activities \".
  3. AIHA. "Webinar: The New Era of Global Exposure Limit Setting Processes - Harmonization on an OEL Hierarchy Approach".
  4. NIOSH Manual of Analytical Methods
  5. "Link to freeware version IHSTAT via AIHA Exposure Assessment Strategies website" https://www.aiha.org/get-involved/VolunteerGroups/Pages/Exposure-Assessment-Strategies-Committee.aspx/
  6. "A Strategy for Assessing and Managing Occupational Exposures, Third Edition Edited by Joselito S. Ignacio and William H. Bullock AIHA Press" http://iweb.aiha.org/iweb/Purchase/ProductDetail.aspx?Product_code=AEAK06-327/


Further reading

See also

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