Understanding the risk of CO poisoning

Much of the work done on construction sites is outdoors, from pouring foundations and driveways to exterior framing and roofing. But at some point the work (and the workers) move inside and into enclosed spaces, often providing relief from heat, cold, and bad weather. But bringing gas-powered equipment indoors can shift that breath of relief to a breathing danger.   

Carbon monoxide (CO) poisoning is an often-overlooked job-site threat. When gasoline or propane-motorized equipment like air compressors and generators are used within enclosed (or partially enclosed) settings, the risk for CO exposure is higher than people think. Ed Protzman, Senior Risk Management Consultant at Builders Mutual, shares his expertise about this hazard and how to avoid potential tragedy.

CO 101

Carbon monoxide results from the incomplete burning of carbon-containing fuels such as natural gas, gasoline, kerosene, oil, or propane. Because it has no odor or color, CO gas is impossible to detect by smell or sight, so you can be breathing it in without knowing it. Moreover, because initial symptoms that include headaches, fatigue, and dizziness, exposure is frequently chalked up to normal job-site physical stressors, cold, or flu. 

Why is CO so harmful? According to OSHA, when CO is breathed in, “it displaces oxygen in the blood and deprives the heart, brain, and other vital organs of oxygen.” Very quickly, a headache and nausea can turn into confusion, collapse, and loss of consciousness. Without rescue, suffocation and death are not far behind. Those with existing heart and lung conditions, and those who already have elevated CO levels, (e.g., from continuous exposure to CO or cigarette smoking), are at an even higher risk for serious neurological damage, coma, and death. 

Common exposure

How prevalent is the threat of carbon monoxide poisoning on the job-site? Well, this question can be answered by asking another one: How often do construction workers use an air compressor indoors to power their nail guns, or run a heaters to warm their work area during cold months? A lot. Even though they may set the compressor or generator near a door of the room they’re working in, the fumes don’t stop at the doorframe. The same holds true when work areas are enclosed with tarps or temporary structures: just because there are openings (including windows and doors) to the space, it doesn’t mean that there is proper ventilation and air movement, and the harmful gas can be building up.

Equally as deceptive are large indoor spaces—like warehouses—that seem to have ample space for CO fumes to dissipate. But this misconception can easily lead to harmful levels of CO and subsequent poisoning. For instance, it’s not unusual for a warehouse worker to leave a forklift or other equipment running while pausing one task to complete another, or to have an idling vehicle sitting at a loading dock in preparation for the day’s tasks.

Common sources of CO exposure on the job-site or in a warehouse (with natural gas, gasoline, kerosene, oil, and propane as equipment fuel source):
    • Portable generators 
    • Air compressors
    • Pressure washers
    • Water pumps
    • Portable heaters
    • Concrete-cutting saws, chainsaws
    • Power trowels
    • Floor buffers
    • Idling forklifts/vehicles
Prevention through awareness

First and foremost, employers need to teach their workers that carbon monoxide poisoning is a real thing on the job-site or in warehouses, and training should include exposure risk factors, symptoms, and prevention. The following can serve as key points for a quick toolbox talk or training text.

    1. Use alternatives to gas-powered equipment (electrical or hydraulic) when working indoors or in confined spaces. 
    2. If you must use gas-powered equipment, never run it in an enclosed space or indoors. Place the equipment outside of the structure, setting it at least 20 feet away with the exhaust pointing away from the work structure. Ensure that the area where the equipment is placed has 3-4 feet of clear space on all sides/above it to ensure optimal performance. 
    3. If gas- or propane-powered equipment is necessary, even with distance and ventilation precautions in place, use job-site or personal CO monitors with an audible alarm. Refer to OSHA or NIOSH standards for continuous/maximum parts per million exposure limits. 
    4. Be alert to the symptoms of low-level CO poisoning, including headaches, nausea, and confusion). Be sure to set up response protocols if CO poisoning is suspected, which include getting to fresh air right away and seeking immediate medical attention.
    5. Be aware of propane space heaters use in colder months—they may seem harmless but can put employees at risk without proper precautions.
    6. Remember that CO danger isn’t just in “confined spaces.” Rooms with open windows, warehouses, and parking garages can all be risky without proper airflow.
    7. Look out for fellow employees and share information about CO exposure and risks. Most importantly, be a good example to coworkers by taking proper safety precautions.

Check out these resources for more information on carbon monoxide hazards, including this safety article from NIOSH, this prevention video from OSHA (in English and Spanish), and this OSHA Quick Card in English and Spanish—perfect for job-site toolbox talks. Of course, if you want additional safety training on this—or any—topic, reach out to your Builders Mutual Risk Management Consultant.