I think it sits in your lungs for a while so not a good idea to sit there breathing it in if it goes off.
It's been replaced by FM200 for confined-room environments such as comms (server) rooms.
Interestingly it's still approved by the FAA I believe for use in aircraft even though it's been banned since 1994. It'll take a while before something with Halon's fire-suppresion properties is approved - a powder suppressant will likely inflict damage to the cargo whereas Halon doesn't.