CARBON MONOXIDE†

Chemical Identification

CAS # 630-08-0
Formula

CO

Synonyms

carbon oxide; flue gas; monoxide; carboxyhemoglobin/COHb

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

Analyte code (IMIS no.) 0560 0560 C730 (COHb)
Sampling group
Sampler/Sampling media Dräger X-am 5600 Multi-Gas Detector with a Dräger XXS CO LC electrochemical sensor. 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 1026 (fully validated) OSHA ID-210 (fully validated)
Notes

Use detector tubes for screening. If greater than PEL, order gas sampling bags.

*Note for sampling with Cali-5-BondTM, 10 liter, five layer aluminized gas sampling bag: This gas sampling bag has an integrated twist on/off valve (V-NPB-2/00) Septum (A-SEPT/.750). The nickel-plated brass connection allows the user to control gas flow into or out of the bag by twisting the barbed stem open (counterclockwise) or closed (clockwise). The jagged barb firmly secures 3/16″ ID sample tubing to the stem of the valve.

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.

Bulk/Wipe Method

Wipe Sampler/Sampling media
Bulk Method

On-Site Screening Techniques

Device CMS Chip Single Gas Detector Single Gas Detector Single Gas Detector Single Gas Detector Single Gas Detector
Model/Type Carbon monoxide, 5-150 ppm range BW Solo (BWS1 CO) Dräger Pac 6500 CO (8327614) Dräger Pac 7000 CO (8318970) GasBadge Pro (1810-0060) ToxiRAE Pro (G02-BF10-100)
Sampling information
(see manufacturer instructions)
Honeywell Safety Dräger Portable Gas Detection Dräger Portable Gas Detection Industrial Scientific Honeywell Safety

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 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:

Visit the ACGIH TLV site for specific data
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

Last Updated Date : 05/17/2024