Its not a silly question at all. The mine is pretty well ventilated and has ventilation doors at various intervals - all of which are jammed open. There is some stale air a bit deeper in - at a point where the roof has fallen in. Where we cooked was in a place called Wheel Flats. A "Flat" is an area which holds a lot of ore and the one we were in had been mined out, leaving quite a large cavern., and given the fresh air input and the size of the cavern, I reckon we just about got away with it! There's also quite a bit of rather suspicious dust in the air - given that there's also a fair amount of galena knocking about as well, it makes you wonder exactly what's in the dust. (?lead)
The other groups did complain that the smell of bacon and sausage was unfair as they only had tuna and tomato sandwhiches. But we had lots of spare scoff, and they could have had some if they'd wanted. Food hygiene regulations were blatently flouted, though.
But whats this ...some stop press latest pics have come in... Santa trapped down a mine with his little helper and another with some blokes stuffing themselves with fatty stuff. Not sure who the eeejit on the left is, showing his fork....
But your brother is quite right, though, mines are fascinating places. I understand there's quite a good coal mine museum - in a real coal mine somewhere near Barnsley/Wakefield area. Has to be worth a trip.