Permissible exposure limit.

A PEL is the enforceable number: 29 CFR 1910.1000 sets most of them as an eight-hour time-weighted average, some with a ceiling that may not be passed at any moment. A TLV is not the same animal. TLVs are published by ACGIH, a private body, and a UK workplace exposure limit or any other OEL is another list again; only the PEL has a federal penalty behind it. OSHA says in its own words that many of these limits are outdated and that plenty of substances have no PEL at all, which is why it publishes annotated tables showing the Cal/OSHA, NIOSH and ACGIH numbers beside its own. For a screen floor that means clearing the PEL on a press wash solvent is a floor, not a verdict on the room. Chasing the enforceable number and ignoring the stricter one is how a shop passes an inspection and still sends people home with headaches.