# 1,3-Butadiene — workplace exposure limit

For 1,3-Butadiene, niosh rel, as stated is Ca See Appendix A; cas no. is 106-99-0, verified against its source on 2026-09-08.

- **Substance:** 1,3-Butadiene _(verified: appears in its own passage below)_
- **CAS No.:** 106-99-0 _(verified: appears in its own passage below)_
- **NIOSH REL, as stated:** Ca See Appendix A _(verified: appears in the quote below)_
- **PEL (ppm):** 1 _(per dir.ca.gov, not stated by the source above)_
- **PEL (mg/m³):** 2.2 _(per dir.ca.gov, not stated by the source above)_
- **STEL (ppm):** 5 _(per dir.ca.gov, not stated by the source above)_
- **STEL (mg/m³):** 11 _(per dir.ca.gov, not stated by the source above)_

## What the source says

> NIOSH REL Ca See Appendix A

## 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 - 1,3-Butadiene

### CAS No.

> CAS No. 106-99-0

## What dir.ca.gov says

> 106990 | | 1,3-Butadiene (see also section 5201) | 1 | 2.2 | | 5 | 11

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

## What osha.gov says

> Butadiene (1,3-Butadiene); See 29 CFR 1910.1051; 29 CFR 1910.19(l) | 106-99-0 | 1 ppm/5 ppm STEL | - | - |

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

## Source

- https://www.cdc.gov/niosh/npg/npgd0067.html
- https://www.dir.ca.gov/title8/5155.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/).