SafeTec Blog

Terminology Refresher :: Exposure Limits & Recommendations


The Occupational Safety and Health Administration (OSHA) uses specific terminology related to the risk assessment and management of activities involving the handling of hazardous chemicals. Included are a few key terms (and acronyms) related to occupational exposure limits and exposure recommendations important to familiarize yourself with.

Occupational Exposure Limit (OEL)

OEL refers to the maximum amount that a hazardous, airborne substance can be present in a work environment without harming the workers. If the substance exceeds the OEL then safety measures must take place. The OEL is set by experts in the industry and is enforced by law.

Permissible Exposure Limits (PEL)

PEL refers to the length of time workers may remain in an area with a hazardous substance, with or without respirators. Most PELs operate under an 8-hour window, but different PELs apply to different substances. Currently over 500 PELs are in place.

Recommended Exposure Levels (REL)

REL refers to the recommended exposure limit as set by the National Institute for Occupational Safety and Health (NIOSH), an organization that uses different chemical terminology from OSHA. NIOSH is a government agency that operates as a third party, outside of OSHA, and makes safety recommendations to OSHA to further advance safety procedures.

Threshold Limit Values (TLV)

TLV refers to how often a worker can be exposed to chemicals and substances, day after day, over the course of an entire work career. TLVs are set by a group called ACGIH, a not-for-profit, non-governmental organization that uses different chemical terminology than OSHA or NIOSH. ACGIH takes workers' health into consideration. They do not assess economic feasibility when making recommendations. Although the ACGIH does not consider economic feasibility, they do recommend that companies adopt strategies to look at the economic and technical feasibility of these standards.

Biological Exposure Indices (BEI)

BEIs are also set by the ACGIH. BEIs test the presence of chemicals in biological media, i.e. blood and urine.

Action Limit

This refers to the time (usually half the time of a PEL) when action must be taken due to a worker's exposure to a chemical. The appropriate action may refer either to exposure monitoring or medical surveillance.

Ceiling Limit

The exposure to a substance or chemical that a worker may never exceed.

Short-Term Exposure Limit (STEL)

The exposure limit during a short time period, generally 15 – 30 minutes.

It's important for those in the industry to understand the appropriate terms, especially when attempting to make a safe work environment for employees and contractors. For further information on chemical terminology, chemical management and the organizations who monitor safety standards, give us a ring!

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