Carbon monoxide safety

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What is carbon monoxide?

Carbon monoxide (CO) is a poisonous, colorless, odorless, and tasteless gas. Although it has no detectable odor, CO is often mixed with other gases that do have an odor. You can inhale carbon monoxide right along with gases that you can smell and not know that CO is present.

CO is a common industrial hazard resulting from the incomplete combustion of natural gas and other material containing carbon, such as gasoline, kerosene, oil, propane, coal, or wood. Forges, blast furnaces, and coke ovens produce CO, but one of the most common sources of exposure in the workplace is the internal combustion engine.

Who is at risk of exposure?

You may be exposed to harmful levels of CO in boiler rooms, breweries, warehouses, petroleum refineries, pulp and paper production, and steel production; around docks, blast furnaces, or coke ovens; or in one of the following occupations:

  • Welder.
  • Mechanic.
  • Firefighter, police officer.
  • Longshoremen.
  • Equipment operator.
  • Tunnel attendant.
  • Taxi driver.
  • Carbon black production, organic chemical synthesizer, metal oxide reducer.
  • People working in poorly ventilated areas and/or confined spaces.

What’s the harm?

Carbon monoxide is harmful when inhaled because it displaces oxygen in the blood and deprives the heart, brain, and other vital organs of oxygen. Large amounts of CO can overcome you in minutes without warning, causing you to lose consciousness and suffocate.

What are the health effects?

The lack of warning signs makes CO especially dangerous. Employees with heart or lung problems are particularly susceptible to CO poisoning. Early signs of acute CO poisoning include headache, blurry vision, drowsiness, dizziness, weakness, and confusion. Initially the victim may have pale skin. Later the skin and mucous membranes turn cherry red due to the CO combining with blood hemoglobin. If the exposure continues, these symptoms may be followed by nausea, vomiting, ringing in the ears, and difficulty breathing. Finally, the victim loses consciousness and enters a coma. If the victim does not receive oxygen, death can occur. If the victim survives, the individual may suffer permanent brain damage. In extremely high CO concentrations, death can occur within only a few minutes.

What can you do if you suspect an exposure?

When you suspect CO poisoning, promptly taking the following actions can save lives:

  • Move the victim immediately to fresh air in an open area.
  • Call 911 or another local emergency number for medical attention or assistance.
  • Administer 100% oxygen using a tight-fitting mask if the victim is breathing.
  • Administer cardiopulmonary resuscitation (CPR) if the victim has stopped breathing.

Warning: You may be exposed to fatal levels of CO poisoning in a rescue attempt. Rescuers should be skilled at performing recovery operations and using recovery equipment. Employers should make sure that rescuers are not exposed to dangerous CO levels when performing rescue operations.

What can employers do to prepare and prevent?

To reduce the chances of CO poisoning, take the following actions:

  • Install an effective ventilation system that will remove CO from work areas.
  • Maintain equipment and appliances (e.g., water heaters, space heaters, cooking ranges) that can produce CO in good working order to promote their safe operation.
  • Consider switching from gasoline-powered equipment to equipment powered by electricity, batteries, or compressed air if it can be used safely.
  • Prohibit the use of gasoline-powered engines or tools in poorly ventilated areas.
  • Provide personal CO monitors with audible alarms if potential exposure to CO exists.
  • Test air regularly in areas where CO may be present, including confined spaces. See Title 29 of the Code of Federal Regulations (CFR) 1910.146.
  • Use a full-face pressure-demand self-contained breathing apparatus (SCBA) certified by the National Institute for Occupational Safety and Health (NIOSH) or a combination full-face pressure-demand supplied-air respirator with auxiliary self-contained air supply in areas with high CO concentrations, i.e., those immediately dangerous to life and health atmospheres. (See 29 CFR 1910.134.)
  • Use respirators with appropriate canisters for short periods under certain circumstances where CO levels are not exceedingly high.
  • Educate workers about the sources and conditions that may result in CO poisoning as well as the symptoms and control of CO exposure.

In addition, if employees are working in confined spaces with suspected CO presence, workers must test for oxygen sufficiency before entering.

What can employees do to prepare and prevent?

Employees should:

  • Report any situation to your employer that might cause CO to accumulate.
  • Be alert to ventilation problems — especially in enclosed areas where gases from burning fuels may be released.
  • Promptly report complaints of dizziness, drowsiness, or nausea.
  • Avoid overexertion if you suspect CO poisoning and leave the contaminated area.
  • Tell your doctor that you may have been exposed to CO.
  • Avoid the use of gas-powered engines while working in enclosed spaces.

What are the OSHA standards for CO exposure?

  • The OSHA permissible exposure limit (PEL) is 50 parts per million (PPM). OSHA standards prohibit worker exposure to more than 50 PPM averaged during an eight-hour time period.
  • The eight-hour PEL for CO in maritime operations is also 50 PPM. However, maritime workers must be removed from exposure if the CO concentration in the atmosphere exceeds 100 PPM.


KEMI does not assume liability for the content of information contained herein. Safety and health remain your responsibility. This information is to be used for informational purposes only and not intended to be exhaustive or a substitute for proper training, supervision or manufacturers’ instructions/recommendations. KEMI, by publication of this information, does not assume liability for damage or injury arising from reliance upon it. Compliance with this information is not a guarantee or warranty that you will be in conformity with any laws or regulations nor does it ensure the absolute safety of any person, place or object, including, but not limited to, you, your occupation, employees, customers or place of business.