---
type: threshold
id: mesityl-oxide-4-methyl-3-pentene-2-one
asset: workplace-exposure-limits
title: "Mesityl oxide; 4-methyl-3-pentene-2-one — US workplace chemical exposure limits: federal OSHA vs Cal/OSHA, side by side"
sources:
  - https://www.dir.ca.gov/title8/5155.html
source_quote: "141797 | | Mesityl oxide; 4-methyl-3-pentene-2-one | 15 | 60 | | 25 | 100"
generated: true
harvested: 2026-08-05
stale_after: 2027-08-05
substance: "Mesityl oxide; 4-methyl-3-pentene-2-one"
pel_ppm: "15"
pel_mgm3: "60"
stel_ppm: "25"
stel_mgm3: "100"
verified: true
---
**Substance:** Mesityl oxide; 4-methyl-3-pentene-2-one

**PEL (ppm):** 15

**PEL (mg/m³):** 60

**STEL (ppm):** 25

**STEL (mg/m³):** 100

> 141797 | | Mesityl oxide; 4-methyl-3-pentene-2-one | 15 | 60 | | 25 | 100

Source: <https://www.dir.ca.gov/title8/5155.html>