Carbon monoxide in tents and shelters

Carbon monoxide is produced by any combustion, and especially when there is too little oxygen. That is exactly the case when a stove or grill burns in a small, poorly ventilated space: the flame uses up the oxygen, burns less and less completely and so produces even more CO.

In the body, oxygen is carried by red blood cells, or more precisely by the red blood pigment haemoglobin. Carbon monoxide binds to this pigment much more strongly than oxygen does and pushes it out. The blood can then deliver less oxygen to the brain, heart and muscles – even though you are breathing normally.

The treacherous part is that the senses get no warning. You can smell smoke but not CO. The first symptoms are vague and easily mistaken for tiredness, a cold or altitude effects. By the time someone realises something is wrong, they may already be too dazed to get themselves to safety.

Bad weather when camping: it is raining or snowing, and it is tempting to light the stove inside the tent or vestibule. This is among the typical causes of accidents. An open door or a vent does not make it safe either.

The grill after the meal: the charcoal is still glowing and giving off pleasant warmth, so the grill is brought into the tent or hut. But cooling embers keep releasing carbon monoxide – often for hours.

A power cut at home: a generator is running in the garage or basement, a camping stove or grill is meant to provide warmth in the flat. That is life-threatening too. And in winter a running vehicle engine can become dangerous if snow blocks the exhaust pipe and fumes get into the car.

The basic rule is short: run stoves, grills, generators, charcoal, embers and fires only outdoors, at a distance from tents, shelters, windows and vents. No exceptions for “just briefly”, “just to warm up” or “with the door open”.

Possible warning signs are headache, dizziness, nausea, weakness, confusion and unusual drowsiness – especially if several people are affected at once or the symptoms appear near a combustion source. Then get to fresh air immediately, bring others with you without staying in the danger area longer than necessary yourself, and call the local emergency number (112 in the EU).

Anyone who may have carbon monoxide poisoning needs medical help, even if they already feel better in the fresh air. Treatment belongs in professional hands; this text deliberately gives no treatment instructions and no exposure limits.

The reason people bring combustion devices inside is almost always cold. The safe answer to that is insulation instead of fire: good ground insulation, a suitable sleeping bag, dry clothing, a hat and huddling together in a group.

Warm drinks and warm food help a great deal – as long as they are prepared outside. A vacuum flask of hot drink, filled outdoors in the evening, brings warmth into the tent without danger.

The same applies at home: keep one room warm, wear layers, use blankets and, during longer outages, go early to warm accommodation or a help point.

Small, well-sealed spaces are especially dangerous because the gas builds up there quickly. Snow can block the openings of tents, snow shelters or exhaust pipes without anyone noticing. And sleep increases the danger: someone asleep notices no symptoms.

Indoor carbon monoxide alarms are a sensible addition, especially if fuels are used for heating or cooking at home. But they never replace the basic rule of not running combustion devices in enclosed spaces.

Carbon monoxide is not the same as smoke and not the same as carbon dioxide. A fire can burn almost smoke-free and still produce carbon monoxide. That is why “I can’t smell anything” is never a sign of safety.