PELs are regulatory limits on the amount or concentration of a substance in the air. They may also contain a skin designation.
PELs are enforceable.
This site contains PDF files of chemical information, such as exposure limits, health hazards, chemical and physical properties, monitoring and measuring procedures, personal protective equipment, etc. Understanding Toxic Substances, An Introduction to Chemical Hazards in the Workplace . Includes a discussion of exposure limits. Currently, approximatly 500 PELs have been established. Existing PELs are contained in 29 CFR 1910.1000, the air contaminants standard.