Glossary / Exposure limits
Occupational exposure limit (OEL)
Occupational exposure limit (OEL) is a general term for an upper limit on the concentration of a hazardous substance in workplace air, set to protect workers' health. It covers legal limits such as OSHA PELs, recommendations such as NIOSH RELs and ACGIH TLVs, and limits set by other countries or companies.
Explanation
Different bodies use different names and have different legal weight. In the United States the enforceable ones are OSHA's Permissible exposure limit (PEL) values. NIOSH's Recommended exposure limit (REL) and ACGIH's Threshold limit value (TLV) are recommendations. In the European Union, limits are set under a mix of binding and indicative lists, and other countries have their own systems. Manufacturers also set their own internal limits, sometimes called occupational exposure bands or company limits, especially for pharmaceuticals and new chemicals.
OELs come in forms matching the effect of concern: an 8-hour Time-weighted average (TWA), a 15-minute Short-term exposure limit (STEL), and a Ceiling limit. Some have notations such as Skin notation. Values are given in Parts per million (ppm) for gases and vapors or in milligrams per cubic meter for particles.
OELs are the benchmark for judging air monitoring results, choosing ventilation and selecting respirators. They are not guaranteed boundaries between safe and unsafe, and they are derived from different data and methods, so values for the same chemical differ between lists. Where several limits exist, many programs apply the most protective one that is reasonably achievable.
SDS Section 8 is where limits are gathered, but the suppliers choose which to show and the list may be incomplete or out of date. Verify against the current source when compliance matters.
What to do and watch for
- Know which limits are legally binding for your location and which are guidance.
- Compare monitoring results against the most protective applicable value.
- Check the date and source of any limit quoted on an SDS.
Where it appears on an SDS
- Section 8: Exposure controls / personal protection. Section 8 lists occupational exposure limit values by source, with the type and averaging period.
SDS content and wording vary by supplier. This page is general reference and does not replace the current SDS for your product.