# Carbon monoxide — US workplace chemical exposure limits: federal OSHA vs Cal/OSHA, side by side

For Carbon monoxide, cas no. is 630-08-0; pel (ppm) is 50; pel (mg/m³) is 55, verified against its source on 2026-08-05.

- **Substance:** Carbon monoxide
- **CAS No.:** 630-08-0
- **PEL (ppm):** 50
- **PEL (mg/m³):** 55

## What the source says

> Carbon monoxide | 630-08-0 | 50 | 55 | - |

## Sources disagree

More than one authority states this, and they do not state the same
thing. Both are reproduced with the source each came from.

### PEL (ppm)

osha.gov says pel (ppm) is **50**, as of 2026-08-05.

> Carbon monoxide | 630-08-0 | 50 | 55 | - |

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

dir.ca.gov says pel (ppm) is **25**, as of 2026-08-05.

> 630080 | | Carbon monoxide | 25 | 29 | 200 ppm

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


### PEL (mg/m³)

osha.gov says pel (mg/m³) is **55**, as of 2026-08-05.

> Carbon monoxide | 630-08-0 | 50 | 55 | - |

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

dir.ca.gov says pel (mg/m³) is **29**, as of 2026-08-05.

> 630080 | | Carbon monoxide | 25 | 29 | 200 ppm

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


## Source

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

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