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What is Carbon Monoxide?

Carbon Monoxide (CO) is an odorless, colorless gas. It prevents the body from using oxygen, which can cause damage to the heart, brain, and other organs – even death. Because it is invisible and has no smell, people often do not realize that they are breathing CO.


Carbon Monoxide Poisoning in Vehicles

If a vehicle is left running in an enclosed space, or if the tailpipe is blocked by snow or ice, CO can build up in the car and create a very dangerous situation. NEVER run your car or truck until it is completely cleared of snow and ice, including the undercarriage.

  • Be sure to clear at least 1 foot of snow all around and under your motor vehicle, including the tailpipe, before starting it.
  • Keep your car windows open to allow for fresh air when warming up your car.

Early symptoms of CO poisoning are feeling drowsy, confusion, headaches, fainting, and dizziness. People often do not realize that they are exposed until they are seriously ill.

If you experience any symptoms, get to fresh air and call 911 immediately.

​To learn more about Carbon Monoxide, read our Fact Sheet here​.
Boston Public Health Commission
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