Symptoms of CO poisoning

Published on January 5, 2009
CO enters the body through breathing. CO poisoning can be confused with flu symptoms, food poisoning and other illnesses. Some symptoms include shortness of breath, nausea, dizziness, light headedness or headaches. High levels of CO can be fatal, causing death within minutes.

The concentration of CO, measured in parts per million (ppm) is a determining factor in the symptoms for an average, healthy adult.

  • 50 ppm: No adverse effects with 8 hours of exposure.
  • 200 ppm: Mild headache after 2-3 hours of exposure.
  • 400 ppm: Headache and nausea after 1-2 hours of exposure.
  • 800 ppm: Headache, nausea, and dizziness after 45 minutes; collapse and unconsciousness after 1 hour of exposure.
  • 1,000 ppm: Loss of consciousness after 1 hour of exposure.
  • 1,600 ppm: Headache, nausea, and dizziness after 20 minutes of exposure.
  • 3,200 ppm: Headache, nausea, and dizziness after 5-10 minutes; collapse and unconsciousness after 30 minutes of exposure.
  • 6,400 ppm: Headache and dizziness after 1-2 minutes; unconsciousness and danger of death after 10-15 minutes of exposure.
  • 12,800 ppm: Immediate physiological effects, unconsciousness and danger of death after 1-3 minutes of exposure.

Source: NFPA's Fire Protection Handbook, 20th Edition.

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