Photo Donald Trung Quoc Don, CC BY-SA 4.0_04.jpg){kind=link}
Carbon monoxide poisoning
The gas you cannot see or smell. How it gets into a tent, a hut, a truck or a boat, the signs, and what to do.
Where it comes from
- Any flame or engine: stoves, heaters, lanterns, generators, charcoal, outboards and vehicles
- A stove or a lantern in a tent, a snow shelter or an ice fishing hut
- A truck or a car stuck in snow with the tailpipe buried and the engine running for heat
- A boat's exhaust drawn back in over the stern, or into the cabin
- A cabin shut tight in winter, with snow or ice blocking a vent or a chimney
What you need
- A battery carbon monoxide alarm for the cabin, and a small one for the tent, hut or camper
- Spare batteries
- Fresh air: a vent open in any shelter where something is burning
How
- If the alarm sounds or more than one person feels sick, get everyone out into fresh air at once.
- Do not stop to find the cause, and do not go back in for anything.
- Call 911. Say you think it is carbon monoxide.
- If someone will not wake or is not breathing, get them out if you can do it quickly, then start CPR if you know how.
- Keep them warm and still while you wait. Give nothing by mouth to someone who is drowsy.
- Shut off the fuel and air the place out from outside before anyone goes back in.
- Anyone who was sick needs a doctor the same day, even if they feel better in the fresh air.
Do and don't
Do
- Trust the alarm over how you feel.
- Clear snow from a vehicle's tailpipe before you run the engine, and crack a window.
- Run a generator outside, well away from doors, windows and vents.
Don't
- Do not cook, heat or run a lantern inside a closed tent or snow shelter.
- Do not sleep in a vehicle with the engine running.
- Do not swim, sit or hang on the stern of a boat while the engine runs.
Watch for
Danger
- Headache, dizziness, feeling sick, weakness, confusion and sleepiness. It feels like the flu, with no fever.
- Several people sick at once, or the dog as well, and better once outside, is carbon monoxide until proved otherwise.
- Sleep hides it. People die without waking. That is why the alarm matters.
- A finger pulse meter reads normal with carbon monoxide in the blood. Do not trust it for this.
- Children, older people, pregnant women and anyone with a heart or lung problem get sick faster.
Notes
The gas has no colour, no smell and no taste. The only warnings are the alarm and how people feel, and by the time you feel it your judgement is already going.
Alarms wear out. Most carry an end of life date on the back. See Propane and carbon monoxide for running propane at the cabin.
Updated 2026-09-28
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