# o-Xylene — workplace exposure limit

For o-Xylene, niosh rel (ppm) is TWA 100; niosh rel (mg/m³) is 435; cas no. is 95-47-6, verified against its source on 2026-09-08.

- **Substance:** o-Xylene _(verified: appears in its own passage below)_
- **CAS No.:** 95-47-6 _(verified: appears in its own passage below)_
- **NIOSH REL (ppm):** TWA 100 _(verified: appears in the quote below)_
- **NIOSH REL (mg/m³):** 435 _(verified: appears in the quote below)_

## What the source says

> NIOSH REL TWA 100 ppm (435 mg/m3) ST 150 ppm (655 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 - o-Xylene

### CAS No.

> CAS No. 95-47-6

## Source

- https://www.cdc.gov/niosh/npg/npgd0668.html

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