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Definition

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A Short Term Exposure Limit (STEL) is defined by ACGIH as the concentration to which workers can be exposed continuously for a short period of time without suffering from:

1. Irritation
2. Chronic or irreversible tissue damage
3. Narcosis of sufficient degree to increase the likelihood of accidental injury, impair self-rescue or materially reduce work efficiency.

Additional Info

STEL's are generally used only when toxic effects have been reported from high acute (short-term) exposures in either humans or animals. An STEL is not a separate independent exposure limit, but supplements time-weighted average limits where there are recognized acute effects from a substance whose toxic effects generally chronic (long-term) in nature.

For example, one can not be exposed to an STEL concentration if the TLV-TWA (time weighted average for an 8 hour shift; see Permissible Exposure Limit (PEL)) would be exceeded. Workers can be exposed to a maximum of four STEL periods per 8 hour shift, with at least 60 minutes between exposure periods.

Books Available

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• "2020 TLV's and BEI's: Based on the Documentation of the Threshold Limit Values for Chemical Substances and Physical Agents & Biological Exposure Indices ...", Paperback, 2020, 254 pages. Estimated price $78.97. Info and/or order .
• "Fundamentals of Industrial Hygiene, Sixth Edition", Hardcover, 2012, 1,248 pages. Estimated price $251.99. Info and/or order .
• "Industrial Ventilation: A Manual of Recommended Practice for Operation and Maintenance, 2nd Ed", Hardcover, 2020. Estimated price $119.96. Info and/or order .
• "Supervisors' Safety Manual, 11th Ed", Hardcover, 2018. Estimated price $168.11. Info and/or order .
• "Safety and Health for Engineers 3rd Ed", Hardcover, 2016, 608 pages. Estimated price $74.35. Info and/or order .

SDS Relevance

PEL's and TLV-STEL's (if they exist) are required in Section 8 (exposure controls/personal protection) of a Safety Data Sheet. These values are usually found for substances that may be inhaled, although some can be absorbed through the skin or eyes (STEL's will often have "-skin" after them when skin exposure is possible). When working with materials that have listed exposure limits, use proper precautions to minimize the generation of a vapor or dust in the first place. Always use appropriate personal protective equipment (PPE) such as gloves, dust masks, and respirators to limit your exposure to chemicals.

Remember, exposure limits are not some magic threshold that define the border between safe and dangerous. A PEL or STEL that was acceptable in 1950 may be recognized as dangerously high today. Therefore, always do everything reasonable to limit the airborne release of chemicals or dusts in the first place.

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Further Reading

• Occupational Chemical Database at OSHA lists the PEL's and/or TWA's for many substances, health effects, and equipment/manufacturers that can monitor concentration for PEL/TWA compliance.
• Hazardous Substance Fact Sheet for Hydrogen Sulfide at the NJ Dept of Health.
• Exposure Monitoring Requirements for Methylene Chloride are discussed by OSHA.
• Workplace Exposure Limits and Levels of Concern are discussed at NOAA.
• Odor Thresholds for Chemicals with Established Health Standards at Contra Costa County, California.
• Occupational Hygiene - Occupational Exposure Limits, a Fact Sheet from the CCOHS.

See also: PEL and TWA, Threshold Limit Values (TLV)

Additional definitions from Google and OneLook.

Entry last updated: Monday, January 16, 2023. This page is copyright 2000-2024 by ILPI. Unauthorized duplication or posting on other web sites is expressly prohibited. Send suggestions, comments, and new entry desires (include the URL if applicable) to us by email.

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