Permissible Exposure Limit (PEL)
TWA concentrations that must not be exceeded during any 8-hour work shift of a 40-hour work week. PELs are subject to change.
Source: API RP 49, Recommended Practice for Drilling and Well Servicing Operations Involving Hydrogen Sulfide, Third Edition, May 2001. Global Standards
Permissible Exposure Limit
Exposure limit that is published and enforced by OSHA as a legal standard (see 29 CFR 1910.1000, Subpart Z), expressed as 8-hour TWAs, ceiling values, and STELs.
Source: API RP 98, Personal Protective Equipment Selection for Oil Spill Responders, First Edition, August 2013. Global Standards