# Diacetone alcohol — workplace exposure limit

For Diacetone alcohol, niosh rel (ppm) is TWA 50; niosh rel (mg/m³) is 240; cas no. is 123-42-2, verified against its source on 2026-09-08.

- **Substance:** Diacetone alcohol _(verified: appears in its own passage below)_
- **CAS No.:** 123-42-2 _(verified: appears in its own passage below)_
- **NIOSH REL (ppm):** TWA 50 _(verified: appears in the quote below)_
- **NIOSH REL (mg/m³):** 240 _(verified: appears in the quote below)_
- **PEL (ppm):** 50 _(per osha.gov, not stated by the source above)_
- **PEL (mg/m³):** 240 _(per osha.gov, not stated by the source above)_

## What the source says

> NIOSH REL TWA 50 ppm (240 mg/m3)

## Where each value comes from

This source states these in separate places, so each value is shown with the passage that states it.

### Substance

> CDC - NIOSH Pocket Guide to Chemical Hazards - Diacetone alcohol

### CAS No.

> CAS No. 123-42-2

## What osha.gov says

> Diacetone alcohol (4-Hydroxy-4-methyl-2-pentanone) | 123-42-2 | 50 | 240 | - |

Source: https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1

## What dir.ca.gov says

> 123422 | | Diacetone alcohol; 4-hydroxy-4-methyl-2-pentanone | 50 | 240

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

## Source

- https://www.cdc.gov/niosh/npg/npgd0178.html
- https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1
- https://www.dir.ca.gov/title8/5155.html

Last verified: 2026-09-08. Review by: 2027-08-05.
Part of [US workplace chemical exposure limits: federal OSHA, Cal/OSHA and NIOSH, side by side](https://referencesource.org/workplace-exposure-limits/).