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Carbon Monoxide

Carbon monoxide (CO) is a colorless, odorless, and toxic gas, which is predominantly produced by incomplete combustion of carbon-containing materials. Incomplete combustion occurs when insufficient oxygen is used in the fuel (hydrocarbon) burning process. Consequently, more carbon monoxide, in preference to carbon dioxide, is emitted. Some examples of this are the following: vehicle exhausts, fuel burning furnaces, coal burning power plants, small gasoline engines, portable gasoline-powered generators, power washers, fire places, charcoal grills, marine engines, forklifts, propane-powered heaters, gas water heaters, and kerosene heaters.

Exposure to carbon monoxide impedes the blood’s ability to carry oxygen to body tissues and vital organs. When carbon monoxide is inhaled, it combines with hemoglobin (an iron-protein component of red blood cells), producing carboxyhemoglobin (COHb), which greatly diminishes hemoglobin’s oxygen-carrying capacity. Hemoglobin’s binding affinity for carbon monoxide is 300 times greater than its affinity for oxygen. As a result, small amounts of carbon monoxide can dramatically reduce hemoglobin’s ability to transport oxygen. Common symptoms of carbon monoxide exposure are headache, nausea, rapid breathing, weakness, exhaustion, dizziness, and confusion. Hypoxia (severe oxygen deficiency) due to acute carbon monoxide poisoning may result in reversible neurological effects, or it may result in long-term (and possibly delayed) irreversible neurological (brain damage) or cardiological (heart damage) effects.

Carbon monoxide exposure can be dangerous during pregnancy for both the mother and the developing fetus. Please contact CDC-INFO (800-232-4636) if you have any questions regarding carbon monoxide exposure during pregnancy.

NIOSH Resources

NIOSH Pocket Guide to Chemical Hazards
Exposure limits, Respirator Recommendations, First Aid, more…
The Pocket Guide is a source of general industrial hygiene information on several hundred chemicals/classes found in the work environment. Key data provided for each chemical/substance includes name (including synonyms/trade names), structure/formula, CAS/RTECS Numbers, DOT ID, conversion factors, exposure limits, IDLH, chemical and physical properties, measurement methods, personal protection, respirator recommendations, symptoms, and first aid.

International Chemical Safety Cards
An ICSC summarizes essential health and safety information on chemicals for their use at the “shop floor” level by workers and employers in factories, agriculture, construction and other work places.

Documentation for Immediately Dangerous to Life or Health Concentrations (IDLH)
The IDLH documents the criteria and information sources that have been used by NIOSH to determine immediately dangerous to life or health concentrations.

NIOSH Manual of Analytical Methods (NMAM)
NMAM is a collection of methods for sampling and analysis of contaminants in workplace air, and in the blood and urine of workers who are occupationally exposed.

NIOSH Worker Notification Program
NIOSH conducts research to prevent illnesses and injuries in the workplace. The NIOSH Worker Notification Program notifies workers and other stakeholders about the findings of these research studies.

NIOSH Publications

Criteria for a Recommended Standard: Occupational Exposure to Carbon Monoxide
DHHS (NIOSH) Publication No. 73-11000 (1972)
Presents a standard to prevent the adverse effects of exposure to Carbon Monoxide over a working lifetime.

NIOSH Hazard ID 3: Carbon Monoxide Poisoning After the Use of Explosives in a Sewer Construction Project
DHHS (NIOSH) Publication No. 98-122 (March 1998)

Occupational Health Guideline for Carbon Monoxide

NIOSH Alert: Controlling Carbon Monoxide Hazard in Aircraft Refueling Operations
DHHS (NIOSH) Publication No. 84-106 (February 1984)


NIOSHTIC-2 is a searchable bibliographic database of occupational safety and health publications, documents, grant reports, and journal articles supported in whole or in part by NIOSH.

Other Related Resources

Acute Exposure Guideline Levels (AEGLs): Carbon Monoxide

American Industrial Hygiene Association (AIHA): Health and Safety Issues in Natural Disasters

ATSDR Toxicological Profile for Carbon Monoxide

CDC Carbon Monoxide Poisoning: Frequently Asked Questions

CDC Carbon Monoxide (CO) Poisoning: Prevention Guidance

CDC Clinical Guidance for Carbon Monoxide Poisoning after a Disaster

CDC MMWR: Non-fatal, Unintentional. Non–Fire-Related Carbon Monoxide Exposures-United States, 2004-2006

CDC National Environmental Public Health Tracking Network: Carbon Monoxide Poisoning

Consumer Product Safety Commission: Carbon Monoxide

emedicinehealth: Carbon Monoxide Poisoning

EPA (NAAQS): Carbon Monoxide

EPA: Indoor Air Quality: Carbon Monoxide

EPA: Protect your Family from Carbon Monoxide Poisoning

European Chemicals Agency (ECHA): Carbon Monoxide

Healthline: Carbon Monoxide Poisoning

National Fire Protection Association (NFPA): Carbon Monoxide

NLM Hazardous Substance Data Bank: Carbon Monoxide

NLM Haz-Map: Carbon Monoxide

NLM Medline Plus: Carbon Monoxide

OSHA (Chemical Sampling): Carbon Monoxide

OSHA Fact Sheet: What is Carbon Monoxide?

OSHA Quick Card: Carbon Monoxide Poisoning

WHO Environmental Health Criteria 213: Carbon Monoxide

WHO Environmental Health Criteria 13: Carbon Monoxide