This was sent to me by a colleague. I'd like to think no one on this forum would make this mistake, but the more people there are who are aware, the less chance of these tragedies continuing to occur.
You may have become aware, from media coverage in recent years, of a number of fatalities due to carbon monoxide poisoning in tents at camping sites. There are of the order of 5 10 incidents (and several near misses) of this type each year and, despite periodic media coverage, they are still occurring and possibly on the increase.
These incidents generally involve people taking a cool, but still burning, portable charcoal fuelled barbeque into a tent, often to provide warmth overnight during cold weather. This should not be done in any circumstances! Ad-hoc tests by others have shown that with modern tent designs (i.e. better sealed against draughts) a concentration of 500ppm of carbon monoxide can be developed in the tent in as little as 3 minutes, a level that can prove fatal in a few hours (e.g. overnight).