# Selenium — workplace exposure limit

For Selenium, niosh rel (mg/m³) is TWA 0.2; cas no. is 7782-49-2, verified against its source on 2026-09-08.

- **Substance:** Selenium _(verified: appears in its own passage below)_
- **CAS No.:** 7782-49-2 _(verified: appears in its own passage below)_
- **NIOSH REL (mg/m³):** TWA 0.2 _(verified: appears in the quote below)_
- **PEL (mg/m³):** 0.2 _(per osha.gov, not stated by the source above)_

## What the source says

> NIOSH REL TWA 0.2 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 - Selenium

### CAS No.

> CAS No. 7782-49-2

## What osha.gov says

> Selenium compounds (as Se) | 7782-49-2 | - | 0.2 | - |

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

## Source

- https://www.cdc.gov/niosh/npg/npgd0550.html
- https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1

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/).