# n-Pentane — workplace exposure limit

For n-Pentane, niosh rel (ppm) is TWA 120; niosh rel (mg/m³) is 350; cas no. is 109-66-0, verified against its source on 2026-09-08.

- **Substance:** n-Pentane _(verified: appears in its own passage below)_
- **CAS No.:** 109-66-0 _(verified: appears in its own passage below)_
- **NIOSH REL (ppm):** TWA 120 _(verified: appears in the quote below)_
- **NIOSH REL (mg/m³):** 350 _(verified: appears in the quote below)_
- **PEL (ppm):** 1000 _(per osha.gov, not stated by the source above)_
- **PEL (mg/m³):** 2950 _(per osha.gov, not stated by the source above)_

## What the source says

> NIOSH REL TWA 120 ppm (350 mg/m3) C 610 ppm (1800 mg/m3) [15-minute]

## 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 - n-Pentane

### CAS No.

> CAS No. 109-66-0

## What osha.gov says

> Pentane | 109-66-0 | 1000 | 2950 | - |

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

## What dir.ca.gov says

> 109660 | | Pentane | 600 | 1,800

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

## Source

- https://www.cdc.gov/niosh/npg/npgd0486.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/).