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Permissible Exposure Limit (PEL)

Last updated: July 24, 2020

What Does Permissible Exposure Limit (PEL) Mean?

The permissible exposure limit (PEL) is a legal limit imposed by the United States Occupational Safety and Health Administration (OSHA) that governs the exposure of personnel to chemical substances or physical conditions such as noise. These limits are typically given based on a time-weighted average (TWA), such as 8 or 10 hours. For example, OSHA’s permissible exposure limit for methyl chloride is 100 ppm with an 8-hour TWA. In other words, a worker may be exposed to that level of substance for no more than 8 hours.

Knowing the permissible exposure limit is important for the safety of personal working near potentially hazardous substances or conditions.


Corrosionpedia Explains Permissible Exposure Limit (PEL)

Permissible exposure limits (PELs) are meant to protect the health and safety of industrial workers. The PEL, along with the time-weighted average (TWA), guides employers on the upper limit of how long personnel may be exposed to certain concentrations of specific substances.

A worker may, however, be exposed to concentrations higher than the PEL level, given that the TWA is not exceeded. For example, according to OSHA, for some substances workers may be exposed to up to three times the PEL-TWA level for no more than 30 minutes.

It should be noted that the current OSHA PELs were written in 1970 and have not been updated. New technological developments have since indicated that the current limits may not sufficiently protect workers’ health.


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