Something that came up earlier in the thread that I think should be discussed more: carbon monoxide.

CO exposure is cumulative. Once it binds to the receptors in the red blood cells, it stays there until the cells die and are replaced normally -- up to 4 months. Even low level exposure can be lethal in only a few hours, and high-level in less than one.

Combustion products should to be vented DIRECTLY outside. Even being in the flow from the source to the outlet will allow CO to accumulate in your blood.

I think anyone considering a bug-in situation should plan on having the stove/whatever outside, somewhere that airflow can't carry the CO inside. A fireplace with the flue open might be safe, but I don't know enough about it to be sure, myself. A wood fire produces a much stronger convection flow than a camp stove would, and I would still be concerned about CO escaping into the room.

Edit: I recognize that most of the people posting here have experience and knowledge of this. I'm posting for the people who might be lurking, and are new to all of this.