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

For Carbon dioxide, cas no. is 124-38-9; pel (ppm) is 5000; pel (mg/m³) is 9000, verified against its source on 2026-08-05.

- **Substance:** Carbon dioxide
- **CAS No.:** 124-38-9
- **PEL (ppm):** 5000
- **PEL (mg/m³):** 9000

## What the source says

> Carbon dioxide | 124-38-9 | 5000 | 9000 | - |

## 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 **5000**, as of 2026-08-05.

> Carbon dioxide | 124-38-9 | 5000 | 9000 | - |

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

dir.ca.gov says pel (ppm) is **5,000**, as of 2026-08-05.

> 124389 | | Carbon dioxide | 5,000 | 9,000 | | 30,000 | 54,000

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


### PEL (mg/m³)

osha.gov says pel (mg/m³) is **9000**, as of 2026-08-05.

> Carbon dioxide | 124-38-9 | 5000 | 9000 | - |

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

dir.ca.gov says pel (mg/m³) is **9,000**, as of 2026-08-05.

> 124389 | | Carbon dioxide | 5,000 | 9,000 | | 30,000 | 54,000

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/).