Carbon Monoxide

Understand the Dangers of Carbon Monoxide

Carbon monoxide (CO) is an odorless, colorless gas. It's formed during incomplete burning of fuels, such as gasoline, kerosene, natural gas, oil, coal, or wood. Carbon monoxide is also found in cigarette smoke and vehicle exhaust. In homes, carbon monoxide can quickly build up from a poorly vented or malfunctioning heater, furnace, range or any fuel-powered appliance, or from a car left idling in a garage.

Carbon monoxide is the most common cause of fatal poisonings. Wisconsin State Law now requires carbon monoxide detectors to be placed on each floor level in all Wisconsin residences.

Take Action if Your CO Detector Sounds

  • Take immediate action if your CO detector sounds or if you have headaches, fatigue, dizziness, shortness of breath, nausea, and/or confusion.
  • Get fresh air immediately. Call your local fire department and move everyone outdoors into fresh air.
  • Do not re-enter the building until it has been inspected and declared safe.

General Information

General CO Recommendations

Ice Arena Resources


Staying Safe from Carbon Monoxide While Boating, P-02211. Review these additional recommendations if you have a fuel-powered boat.

Additional Resources

For Health Professionals

Additional Information

How to Avoid Exposure

About 50% of all CO poisonings occur in the home. Other common settings include cars, cabins, and tents. Follow these important steps to avoid carbon monoxide poisonings:

  • All homes must be equipped with carbon monoxide detectors. Carbon monoxide detectors function similarly to smoke detectors and are available at most hardware stores.
  • Have your furnace, gas stove, and fireplace checked annually by a qualified professional. Have the professional check for proper ventilation and function.
  • Never run an engine in an enclosed space, such as a garage. This includes cars, snowmobiles, generators, and lawn mowers. Review our fact sheet on using generators safely, P-01561. (PDF)
  • Never use a gas oven to heat a home.

Health Effects

Being around low levels of this odorless gas can produce a throbbing headache, dizziness, fatigue, mental confusion, and shortness of breathe. Higher exposures result in severe headache, weakness, dizziness, nausea, irregular heartbeat and unconsciousness. Occasionally, these symptoms can be mistaken for symptoms of the flu.

Exposure to very high levels of carbon monoxide can cause seizures, coma, respiratory failure, and death. Exposure during pregnancy is associated with birth defects and fetal death. In addition to the toxic effects of CO, this gas is very flammable and high concentrations may be explosive.


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Last Revised: January 28, 2019