Weekly Safety Meeting – Carbon Monoxide: The Invisible Killer

Carbon monoxide is an odorless, colorless gas that often goes undetected, striking victims caught off guard or in their sleep.

More than 400 people in the U.S. die from unintentional carbon monoxide poisoning every year, according to the Centers for Disease Control and Prevention. More than 20,000 visit the emergency room and more than 4,000 others are hospitalized.

This “invisible killer” is produced by burning fuel in cars or trucks, small engines, stoves, lanterns, grills, fireplaces, gas ranges, portable generators, or furnaces. When the gas builds up in enclosed spaces, people or animals who breathe it can be poisoned. Ventilation does not guarantee safety.

Sources of Carbon Monoxide:

  • Running a “jumping jack” in a trench;
  • Saw cutting or pressure washing indoors;
  • Confined spaces along heavily traveled roads;
  • Burning wood, paper, or plastic products;
  • Welding when carbon dioxide shielding gas is used; § Propane space heaters; and
  • Forklifts indoors.

Preventing Carbon Monoxide Exposure:

  • Never use a generator indoors or in enclosed or partially enclosed spaces such as garages, crawl spaces, and basements.
    • Opening windows and doors in an enclosed space may prevent CO buildup.
  • Make sure the generator has 3-4 feet of clear space on all sides and above it to ensure adequate ventilation.
  • Do not use a generator outdoors if placed near doors, windows, or vents which could allow CO to enter and build up in occupied spaces.
  • When using space heaters and stoves ensure that they are in good working order to reduce CO buildup, and never use in enclosed spaces or indoors.
  • Consider using tools powered by electricity or compressed air, if available.
  • Look for signs and symptoms in workers (shortness of breath, nausea, headaches, and dizziness).

At lower levels, people sometimes mistake the symptoms of CO exposure for the flu, or do not associate their severe headache and nausea with carbon monoxide exposure. Carbon monoxide is serious and deserves our attention.

Symptoms of Carbon Monoxide Poisoning:

The U.S. Fire Administration has put together materials on the dangers of carbon monoxide, including a list of carbon monoxide poisoning symptoms.

Symptom severity varies depending on the level of carbon monoxide and duration of exposure. As noted, mild symptoms sometimes are mistaken for flu.

Low to moderate carbon monoxide poisoning is characterized by:

  • Headache;
  • Fatigue;
  • Shortness of breath;
  • Nausea; and
  • Dizziness.

High-level carbon monoxide poisoning results in:

  • Mental confusion;
  • Vomiting;
  • Loss of muscular coordination; and
  • Loss of consciousness.

Possible Carbon Monoxide Poisoning:

  • Immediately evacuate and go to an open area with fresh air.
  • Call 911 for medical attention and assistance;
  • If the victim is breathing, provide 100% oxygen using a tight-fitting mask.
  • If the victim is not breathing, administer CPR.
  • Do not reenter the premises until they have been deemed safe.


Carbon monoxide poisoning can be almost impossible to detect because the gas is colorless, odorless and tasteless. Knowing the dangers of carbon monoxide, how to prevent exposure, and what to do if you see someone showing symptoms of poisoning is important in keeping you and your coworkers safe.

Download flyer: SMOTW_745_Carbon Monoxide_The Invisible Killer

Download Spanish flyer: SMOTW_745_Carbon Monoxide_The Invisible Killer_esp

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