Carbon monoxide … a silent killer

Carbon monoxide (CO) is a colorless, odorless, toxic gas that can overcome people without warning. Each year, hundreds of people die from unintentional CO poisoning, often while operating gasoline-powered tools or generators in buildings or semi-enclosed spaces without adequate ventilation.

CO results from the incomplete burning of natural gas and any other material containing carbon, such as gasoline, kerosene, oil, propane, coal, or wood. It can build up indoors and poison people and animals who breathe it. Harmful levels of CO are a potential danger to anyone who works around equipment that uses internal combustion. In addition to generators and gasoline-powered tools, other sources of exposure include space heaters, welding, floor buffers, and concrete cutting saws.

OSHA examples

• An employee was using an electric handheld grinder to finish an installed concrete floor. A coworker was operating a propane-powered walk-behind floor grinder at the same time. The first employee was overcome by CO, found unresponsive, and passed away due to overexposure to CO. The coworker was found semiconscious and hospitalized due to CO overexposure.
• An employee stepped into an attached garage to take a smoke break inside a running vehicle with the garage doors closed. While inside the vehicle, the employee was on the phone with a friend until she lost consciousness. The friend contacted emergency medical services. The employee was transported to the hospital, where she died from CO overexposure.
• An employee was repairing a gasoline-powered lawn mower engine indoors, with the windows and doors closed. After working on the engine, the employee was found dead in the work area due to CO poisoning.

Symptoms of CO exposure

Symptoms of CO exposure include headaches, dizziness, drowsiness, nausea, vomiting, and tightness across the chest. Employees who experience symptoms should get to fresh air right away and seek immediate medical attention.

Reducing risk

To reduce the chances of CO poisoning in the workplace, employers should:

• Install an effective ventilation system to remove CO from work areas;
• Maintain equipment and appliances (e.g., water heaters, space heaters) that can produce CO in good working order to promote their safe operation and to reduce CO formation;
• When feasible, switch from oil- and gas-powered equipment to equipment that uses electricity, batteries, or compressed air;
• Prohibit the use of internal combustion engines or tools in poorly ventilated areas;
• Provide personal CO monitors with audible alarms if there’s potential for exposure to CO;
• Test air often in areas where CO may be present, including confined spaces.
• Do not allow employees to enter confined spaces where CO is suspected without first testing for oxygen sufficiency;
• Install area CO monitors with audible alarms;
• Use correct respirators when necessary; and
• Train workers to recognize conditions where CO may form, signs and symptoms of CO poisoning, and what to do if they suspect CO poisoning.