Generator Carbon Monoxide on Enclosed Sites

Why it matters

Carbon monoxide has no color, no smell, and no warning: you feel a headache, then sleepy, then nothing. A portable generator produces as much CO as hundreds of idling cars, and running one in a garage, basement, or tented enclosure kills workers every year, sometimes several from the same crew. Even near a doorway or window, exhaust drifts indoors. Today: where generators go, and where they never go.

Hazards

• ⚠ Generators running inside garages, basements, and enclosed floors
• ⚠ Exhaust drifting in through doors, windows, and fresh-air intakes
• ⚠ Tented and plastic-wrapped enclosures trapping exhaust in winter
• ⚠ CO from multiple engines stacking up faster than one alone
• ⚠ Early symptoms (headache, dizziness, nausea) blamed on flu or fatigue
• ⚠ No CO monitor where fuel engines run near enclosed work

Controls and safe practices

• ✓ Generators run OUTSIDE only, at least 20 feet from doors, windows, and intakes, exhaust pointed away.
• ✓ Never inside a structure, garage, or enclosure, even with doors open, even for a few minutes.
• ✓ Use extension cords rated for the load to reach the work instead of moving the generator closer.
• ✓ CO monitors in enclosed or semi-enclosed work areas whenever engines run nearby.
• ✓ Winter enclosures and tenting get a ventilation plan before engines or heaters go in.
• ✓ Headache or dizziness on a site with engines: get to fresh air and report it immediately. Do not lie down to shake it off.
• ✓ If someone collapses in an enclosed space, do not rush in behind them; ventilate and call 911.

Crew discussion questions

1. Where is our generator sitting right now, and where does its exhaust go?
2. What enclosed or wrapped areas on this site could trap CO?
3. Do we have a CO monitor, and who checks it?
4. What symptoms have we been writing off as tiredness?

Applicable OSHA standards

29 CFR 1926.55

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