CARBON MONOXIDE (and CO by COHb)†

Chemical Identification
Chemical Identification
CAS # 630-08-0
Formula

CO

Synonyms

carbon oxide; flue gas; monoxide; carboxyhemoglobin/COHb

Physical Properties
Physical Properties
Physical description Colorless, odorless gas.
Boiling point -313°F Molecular weight 28.0
Freezing point/melting point -337°F Vapor pressure >35 atm
Flash point Vapor density 0.97
Specific gravity 0.791 at -312.7°F Ionization potential 14.01 eV
Lower explosive limit (LEL) 12.5% Upper explosive limit (UEL) 74%
NFPA health rating 3 NFPA fire rating 4
NFPA reactivity rating 0 NFPA special instruction
Vapor hazard ratio (VHR)
Historical exceedance percentage
Target organs
Monitoring Methods Used by OSHA
Monitoring Methods Used by OSHA
Analyte code (IMIS no.) 0560 C730 (COHb)
Sampling group
Sampler/Sampling media Five layer aluminized gas sampling bag [Calibrated Instruments GSB-P/10]
Sampling time*

Contact the SLTC Physical Measurements Team Leader in cases where CO poisoning affects more than 4 individuals. The most practical use of resources sometimes requires evaluating the most severely affected employees.

Sampling volume (TWA)*

2-5 L

Sampling flow rate (TWA)*

0.01-0.05 L/min

Sampling volume (STEL/Peak/C)*

2-5 L

Sampling flow rate (STEL/Peak/C)*

0.3 L/min

Analytical method instruments GC-DID
Method reference OSHA ID-210 (fully validated)
Notes

COHb analysis is a routine measurement during the medical response to a suspected CO-poisoning incident or from an autopsy after a suspected CO-poisoning incident. As a result, the COHb analysis is performed using a blood-gas instrument that is part of a quality system. The COHb analysis is not performed at the SLTC.

Carbon monoxide (CO) exposure is determined by calculation based on carboxyhemoglobin (COHb) measurements provided by medical professionals as described below. OSHA uses a modified Coburn, Forster, Kane (CFK) Calculation. The documented SLTC modifications (printed in the supplemental report that accompanies the results) use a more accurate version of the CFK equation than the closed-form [e.g., ppm CO = f(x,y,z,...)] version used in the 1972 NIOSH criteria document for the purpose of calculating the 8-hr TWA ppm REL that would result in a 5% COHb level [U.S. Department of Health, Education, and Welfare: Criteria for a Recommended Standard - Occupational Exposure to Carbon Monoxide. Pub. No. HSM 73-11000. NIOSH, Cincinnati, OH (1972).]

The calculation also provides an incident-specific sampling and analytical error (SAE) based on a Monte-Carlo approach designed to deal with the uncertainties in the data. The calculation is performed at the SLTC and the results are critically assessed for correctness by the SLTC experts prior to reporting. The SLTC is available to assist the CSHO with acquiring the data and interpreting the results.

Special requirements

The exposure incident is documented on a worksheet. Personal information is used to assess the affect of any tobacco smoking behavior (before, during and after the exposure), blood volume, and activity levels (during and after the exposure). Post-exposure delay to sampling is preferable less than approx 6 hours for living persons. Longer delays may result in significantly higher SAEs or the inability to distinguish an overexposure from baseline for an individual. Contact Scott Jones at 801-233-4962 [OSHA staff only].

For further information please enroll in the Carboxyhemoglobin (COHb) training resource in course mill “TR_CO Calculated from Carboxyhemoglobin”.

* All sampling instructions above are recommended guidelines for OSHA Compliance Safety and Health Officers (CSHOs), please see the corresponding OSHA method reference for complete details.

Wipe Method
Wipe Method
Sampler/Sampling media
Bulk Method
Bulk Method
On-Site Screening Techniques
On-Site Screening Techniques
Device CMS Chip
Model/Type Carbon monoxide, 5-150 ppm range
Sampling information
(see manufacturer instructions)
Exposure Limits
Exposure Limits
OSHA PEL
8-hour TWA
(ST) STEL
(C) Ceiling
Peak
NIOSH REL
Up to 10-hour TWA
(ST) STEL
(C) Ceiling
ACGIH TLV©
8-hour TWA
(ST) STEL
(C) Ceiling
CAL/OSHA PEL
8-hour TWA
(ST) STEL
(C) Ceiling
Peak
PEL-TWA

50 ppm (55 mg/m³)

REL-TWA

35 ppm (40 mg/m³)

TLV-TWA

25 ppm [1989]

PEL-TWA

25 ppm (29 mg/m³)

PEL-STEL REL-STEL TLV-STEL PEL-STEL

200 ppm

PEL-C REL-C

200 ppm (229 mg/m³)

TLV-C PEL-C
Skin notation

N

Skin notation

N

Skin notation

N

Skin notation

N

Notes:

See 29 CFR 1910.1000 Table Z-1.

Notes: Notes:

BEI®

Notes:
Health factors:  See NIH-NLM PubChem. IDLH

1200 ppm

Carcinogenic classifications: Not listed Notes:
AIHA emergency response planning guidelines - ERPG-1/ERPG-2/ERPG-3:

200 ppm/350 ppm/500 ppm

Additional Resources and Literature References
Additional Resources and Literature References

NOAA: CAMEO Chemicals - Carbon monoxide

NIOSH: Pocket Guide to Chemical Hazards - Carbon monoxide

Literature References

  • ACGIH: Documentation of the Threshold Limit Values (TLVs) and Biological Exposure Indices (BEIs) - Carbon monoxide. See annual publication for most recent information.
  • Occupational Health Guidelines for Chemical Hazards. DHHS/ NIOSH Publication No. 81-123, (January 1981). Provides a table of contents of guidelines for many hazardous chemicals. The files provide technical chemical information, including chemical and physical properties, health effects, exposure limits, and recommendations for medical monitoring, personal protective equipment (PPE), and control procedures.
  • ATSDR: Toxicological profile for carbon monoxide. June 2012.
  • EPA: Integrated Science Assessment for Carbon Monoxide (Final Report). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-09/019F. January 29, 2010.
  • NIOSH: Criteria Document for a Recommended Standard - Occupational Exposure to Carbon Monoxide. 1972.
  • Sari I, Zengin S, Ozer O, Davutoglu V, Yildirim C, Aksoy M: Chronic carbon monoxide exposure increases electrocardiographic P-wave and QT dispersion. Inhal Toxicol. 20(9):879-84, July 2008.

Last Updated Date : 01/28/2021