---
kind: "section"
citation: "29 C.F.R. § 1917.24"
title: "29"
number: "1917.24"
heading: "Carbon monoxide."
url: "https://uscodex.org/cfr/29/1917.24"
---

# §1917.24. Carbon monoxide.

- (a) **Exposure limits.** The carbon monoxide content of the atmosphere in a room, building, vehicle, railcar, or any enclosed space shall be maintained at not more than 50 parts per million (ppm) (0.005%) as an eight hour average area level and employees shall be removed from the enclosed space if the carbon monoxide concentration exceeds a ceiling of 100 ppm (0.01%).
- (b) **Testing.** Tests to determine carbon monoxide concentration shall be made when necessary to ensure that employee exposure does not exceed the limits specified in [paragraph (a)](#a) of this section.
- (c) **Instrumentation.** Tests for carbon monoxide concentration shall be made by designated persons using gas detector tube units certified by NIOSH under [30 CFR part 11](/cfr/30/part11.md) or other measuring instruments whose accuracy is as great or greater.
- (d) **Records.** A record of the date, time, location and results of carbon monoxide tests shall be available for at least thirty (30) days.

## Notes

### Amendments

[48 FR 30909, July 5, 1983, as amended at 49 FR 28551, July 13, 1984; 61 FR 5509, Feb. 13, 1996; 62 FR 40197, July 25, 1997]

### Authority

Authority: 33 U.S.C. 941; 29 U.S.C. 653, 655, 657; Secretary of Labor's Order No. 12-71 (36 FR 8754), 8-76 (41 FR 25059), 9-83 (48 FR 35736), 1-90 (55 FR 9033), 6-96 (62 FR 111), 3-2000 (65 FR 50017), 5-2002 (67 FR 65008), 5-2007 (72 FR 31160), 4-2010 (75 FR 55355), 1-2012 (77 FR 3912), 8-2020 (85 FR 58393), or 7-2025 (90 FR 27878), as applicable; and 29 CFR part 1911. Sections 1917.28 and 1917.31 also issued under 5 U.S.C. 553. Section 1917.29 also issued under 49 U.S.C. 1801-1819 and 5 U.S.C. 553.

### Source

Source: 48 FR 30909, July 5, 1983, unless otherwise noted.

### Amendments

[48 FR 30909, July 5, 1983, as amended at 49 FR 28551, July 13, 1984; 61 FR 5509, Feb. 13, 1996; 62 FR 40197, July 25, 1997]