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Carbon Monoxide Poisoning

Exposure and Risk

Carbon monoxide, or CO, is a toxic gas that you cannot see or smell. CO is given off whenever fuel or other carbon-based materials are burned. CO usually comes from sources in or near your home that are not properly maintained or vented.

You may be exposed to unsafe levels of CO by:

  • using poorly maintained or unvented heating equipment;
  • improperly vented natural gas appliances like stoves or water heaters;
  • running vehicles in garages or other enclosed spaces;
  • using a gas stove, grill, or oven to heat the home;
  • house or building fires;
  • clogged chimneys or blocked heating exhaust vents;
  • running generators or gas-powered tools indoors or outside near windows, doors, or vents;
  • cooking with a charcoal or gas grill inside the home or other enclosure;
  • using a propane camp stove, heater, or light inside a tent; and
  • being near boat engine exhaust outlets.

Learn how CO poisoning affects the body.


All people are at risk for CO poisoning. Unborn babies, infants, the elderly, and people with chronic heart disease, anemia, or respiratory problems are generally more at risk than others.

Symptoms and Health Effects

Breathing CO can cause headache, dizziness, vomiting, and nausea. If CO levels are high enough, you may become unconscious or die. Exposure to moderate and high levels of CO over long periods of time has also been linked with increased risk of heart disease. People who survive severe CO poisoning may suffer long-term health problems.

Scientists are not sure what the health effects are when a person is exposed to low levels of CO over a long period of time. Better tracking of CO poisoning and exposure can help us learn about the effects of long-term exposures to low levels of CO.

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