Carbon Monoxide Poisoning

What Happens

Carbon monoxide poisoning occurs as carbon monoxide mixes and binds with hemoglobin in the blood to form carboxyhemoglobin (COHb). When carbon monoxide binds to hemoglobin, less oxygen gets transported to body tissues and vital organs such as the brain and heart. The bond between carbon monoxide and hemoglobin is approximately 250 times stronger than the bond between oxygen and hemoglobin.²

Several factors determine how carbon monoxide poisoning can affect you, including:³

• The amount of ventilation in the area where carbon monoxide is present.
• The amount of carbon monoxide inhaled.
• The length of time you are exposed to carbon monoxide.
• Your age. Infants, small children, and older adults are more easily affected and may have more severe symptoms.
• Your general health. People with other illnesses, such as heart disease, are more easily affected and may have more severe symptoms.
• The amount of carbon monoxide already in the blood of a person who smokes tobacco. Smokers already have some carbon monoxide in their blood and may have more severe symptoms.
• Altitude. The higher the altitude, the less oxygen is present in the air to compete with the carbon monoxide.

Symptoms of carbon monoxide poisoning change at different concentrations of carboxyhemoglobin in the blood.

If a woman is pregnant, the fetus is at high risk for developing carbon monoxide poisoning. It takes longer for carbon monoxide to be eliminated from the fetus's blood than from the mother's blood.³

Carbon monoxide poisoning can occur suddenly (inhaling a large amount of carbon monoxide over a short period of time), or it can occur slowly (inhaling a small amount of carbon monoxide over a long period of time).

• Death from carbon monoxide poisoning can occur within 10 minutes at very high concentrations.
• A person with mild symptoms of carbon monoxide poisoning may actually be severely poisoned.
• A person may have a delayed reaction to carbon monoxide poisoning, with symptoms occurring after exposure.
• A person who survives a severe case of carbon monoxide poisoning may develop permanent memory loss or brain damage.

There may be long-term effects of carbon monoxide poisoning, with symptoms that usually develop 2 to 40 days after exposure. These long-term symptoms can occur even if you were treated. Symptoms may include memory loss, changes in personality, disorientation, impaired reasoning ability, and behavioral and learning difficulties.

A study was done that looked at one long-term effect of carbon monoxide poisoning. The study found that people who had damage to the heart from moderate to severe carbon monoxide poisoning were more likely to die at a younger age than people who did not have damage to the heart from the poisoning.⁴

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Author:	Maria G. Essig, MS, ELS	Last Updated: March 18, 2008
Medical Review:	Caroline S. Rhoads, MD - Internal Medicine R. Steven Tharratt, MD, MPVM, FACP, FCCP - Pulmonology, Critical Care, Medical Toxicology
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