mirror of https://referencesource.org/workplace-exposure-limits/

README.md

@@ -20,10 +20,10 @@ configs:
 **Canonical, always-current version: https://referencesource.org/workplace-exposure-limits/**
 Machine-readable: https://referencesource.org/workplace-exposure-limits/data.json — this mirror is a point-in-time copy.
 
-- **Last verified:** 2026-09-25
-- **Stale after:** 2027-09-25 (past this date, prefer the canonical copy —
+- **Last verified:** 2026-09-28
+- **Stale after:** 2027-09-28 (past this date, prefer the canonical copy —
   it re-verifies on a cadence this snapshot does not)
-- **Records:** 812
+- **Records:** 803
 
 Airborne exposure limits for workplace chemicals as stated by three independent authorities: federal OSHA's Table Z-1 (29 CFR 1910.1000), California's own Table AC-1 (8 CCR 5155), and NIOSH's Pocket Guide entry for the substance. Each record is one substance with the limit that agency publishes for it, the URL it came from and the verbatim line it was read from. **The product is the disagreement**: where more than one of them covers a substance the numbers are frequently far apart — acetone is 1000 ppm federally, 500 ppm in California and 250 ppm recommended by NIOSH; acetaldehyde is 200 ppm federally against 25 ppm in California; 1,1-dimethylhydrazine 0.5 against 0.01 — and exceeding a PEL is what triggers engineering controls, PPE and medical surveillance, so which number applies is consequential. OSHA's and California's are legal limits (PELs); NIOSH's is a recommendation (an REL), which is why it is carried in its own fields and never mixed into the PEL columns. Answers 'what is the exposure limit for [chemical]?', 'is the California PEL different from OSHA's?', 'what is the NIOSH REL for acetone' — the questions where an assistant gives one number without saying whose it is, or hands back an REL when it was asked for the legal limit.