Halon is extremely dangerous and most datacentres built in the last twenty years avoid using it for that reason. The last halon datacentre I was in had breathi

Halon is extremely dangerous and most datacentres built in the last twenty years avoid using it for that reason. The last halon datacentre I was in had breathing apparatus within easy reach no matter where you were standing in the place. Two paces, at most, to grab a mask. You do have seconds if it goes off, and that mask is only to give you enough time to run out of the room. The newer stuff is less hostile to organic life, so there's no reason for a respirator.