A great number of carbon monoxide deaths each year are from charcoal. Seems people will attempt to use a small BBQ grill for warmth in a travel trailer. Nothing eats oxygen like charcoal.
It happened in the Dallas area last week. The gas company had shut off an elderly couple and the couple used a charcoal grill in their bedroom.
Charcoal holds within its porous structure enough oxygen to burn even when outside air is virtually depleted, as a consequence, the amount of CO released far exceeds the amount of CO2 produced and it can burn overnight in a grille basin with the lid down.
CO is almost the same weight as air and goes into flux easily saturating the air about it; as you breathe it in it is immediately treated as oxygen and proceeds to destroy your red blood cells turning your blood a bright red and rendering it useless to your tissues.