The Silent Killer: Carbon Monoxide

Centers for Disease Control and Prevention National Center for Environmental Health Division of Environment Hazards and Health Effects Air Pollution and Respiratory Health Branch


February 08, 2013

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In This Article

Carbon Monoxide: Recognizing the Silent Killer

After Hurricane Sandy, it may have poisoned more than 270 homeowners and killed as many as a dozen.[1]

"It" is carbon monoxide (CO), an odorless, colorless, poisonous gas that can cause sudden illness and death if present in sufficient concentration in ambient air. Power outages during emergencies such as hurricanes or winter storms often lead to the use of alternative sources of fuel or electricity for heating, cooling, or cooking. Such alternative practices can cause CO to build up indoors.

Furthermore, nonemergency poisonings, most often associated with defective home heating systems, "warming up" of vehicles in attached garages, and recreational activities such as boating, contribute to the more than 15,000 emergency department visits and 450 deaths linked to CO poisoning in the United States each year. Because the symptoms and signs of CO poisoning are variable and nonspecific, they are often mistaken for other conditions, and the true number of cases -- and deaths -- is thought to be significantly higher.

How to Recognize CO Poisoning

The most common symptoms of CO poisoning are headache, dizziness, weakness, nausea, vomiting, chest pain, and altered mental status.

The clinical presentation of CO poisoning is the result of its underlying systemic toxicity. Its effects are caused not only by impaired oxygen delivery but also by disrupting oxygen utilization and respiration at the cellular level, particularly in high-oxygen-demand organs (eg, heart, brain).

Symptoms of severe CO poisoning include malaise, shortness of breath, headache, nausea, chest pain, irritability, ataxia, altered mental status and other neurologic symptoms, loss of consciousness, coma, and death. Signs include tachycardia, tachypnea, hypotension, various neurologic findings such as impaired memory, cognitive and sensory disturbances, metabolic acidosis, arrhythmias, myocardial ischemia or infarction, and noncardiogenic pulmonary edema, although any organ system might be involved.

With a focused history, exposure to a CO source might become apparent. Appropriate and prompt diagnostic testing and treatment are very important.

No fever is associated with CO exposure. CO poisoning should be suspected when a patient presents with the symptoms noted above, reports a history of exposure, or is one of multiple patients with similar complaints.