OSHA sets enforceable permissible
exposure limits (PELs) to protect workers against the health effects of exposure
to hazardous substances. PELs are regulatory limits on the amount or
concentration of a substance in the air. They may also contain a skin
designation.
OSHA PELs are based on an 8-hour time weighted average (TWA) exposure.
The following questions link to information relevant to permissible exposure limits (PELs).