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Permissible exposure limit

The Permissible Exposure Limit (PEL or OSHA PEL) is a legal limit in the United States for exposure of an employee to a substance or physical agent. For substances it is usually expressed in parts per million (ppm), or sometimes in milligrams per cubic metre (mg/m3). Units of measure for physical agents such as noise are specific to the agent. Permissible Exposure Limits are established by the Occupational Safety and Health Administration (OSHA).

A PEL is usually given as a time-weighted average (TWA), although some are Short Term Exposure Limits (STEL) or Ceiling Limits. A TWA is the average exposure over a specified period of time, usually a nominal eight hours. This means that, for limited periods, a worker may be exposed to concentrations higher than the PEL, so long as the average concentration over eight hours remains lower.

A Short Term Exposure Limit is one that addresses the average exposure over the a 15-30 minute period of maximum exposure during a single work shift.

A Ceiling Limit is one that may not be exceeded, and is applied to irritants and other materials that have immediate effects.

See also

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Permissible_exposure_limit". A list of authors is available in Wikipedia.
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