Reference Source

Carbon dioxide — workplace exposure limit

What is the pel (ppm) for Carbon dioxide — workplace exposure limit?

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

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

osha.gov, retrieved 2026-08-05

5000
The most of this substance workplace air may legally contain, averaged over an 8-hour shift — OSHA's permissible exposure limit (PEL), in parts per million, from the agency's own table row quoted below. Where federal OSHA and Cal/OSHA disagree, both limits are stated, each with its own agency's table row as evidence. NIOSH's number, where there is one, is shown separately: it is a recommended limit, not a legal one, and it is often the strictest of the three.
Sourceosha.gov
Verified
Review by
DatasetUS workplace chemical exposure limits: federal OSHA, Cal/OSHA and NIOSH, side by side
Substance
Carbon dioxide verified
CAS No.
124-38-9 verified
PEL (ppm)
5000 verified
PEL (mg/m³)
9000 verified
STEL (ppm)
30,000 per dir.ca.gov
STEL (mg/m³)
54,000 per dir.ca.gov
NIOSH REL (ppm)
TWA 5000 per cdc.gov
NIOSH REL (mg/m³)
9000 per cdc.gov

What cdc.gov says

NIOSH REL TWA 5000 ppm (9000 mg/m3) ST 30,000 ppm (54,000 mg/m3)

cdc.gov, retrieved 2026-09-08

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 — deciding between them is yours, not ours.

PEL (ppm)

osha.gov says pel (ppm) is 5000, as of 2026-08-05.

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

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

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 | - |

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

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

Sources

Last verified against source: . Due for re-check by . This page as Markdown · OKF bundle · full dataset as JSON.

What is the OSHA exposure limit for this substance?Find the exposure limit for a substance in workplace air — federal OSHA, California and NIOSH, side by side.