But the replacement of all the air by water vapour is harmful for firefighters and other people still in the building: the water vapour can carry much more heat than air at the same temperature (one can be burnt by water vapour at 100 ??C (212 ??F) above a boiling saucepan, whereas it is possible to put an arm in an oven???without touching the metal!???at 270 ??C (520 ??F) without damage).