Permissible Exposure LimitPEL

The Permissible Exposure Limit — PEL — is the legally enforceable airborne concentration of a chemical OSHA sets under 29 CFR 1910, the level the employer is required to keep the worker below, and the number that carries the citation if the industrial-hygiene monitoring shows the exposure past it. The PELs are codified in the 29 CFR 1910.1000 Z-tables for the air contaminants, and the substance-specific standards — 1910.1025 for lead, 1910.1028 for benzene, 1910.1048 for formaldehyde — carry the medical-surveillance and the exposure-assessment obligations on top of the limit. The PEL is the floor the law sets, and the eight-hour time-weighted average is the form most of them take, with the ceiling and the short-term limits on the few the acute risk demands.

The weakness of the PEL is its age. Most of the OSHA PELs were adopted from the 1968 ACGIH TLVs at the founding of the agency in 1971, and the agency has not been able to update them in bulk since, so the PEL for a chemical is the science of fifty years ago frozen into law, and many are not health-protective by the modern toxicology. The result is that the industrial hygienist who works to the PEL alone protects the worker to a 1968 standard, and the honest EHS programme treats the PEL as the legal floor and the ACGIH TLV or the NIOSH REL as the health target the monitoring is actually designed to. The PEL is what the inspector reads; the TLV is what the worker needs. See TLV, SDS, and HazCom.