There are different types of Halon fire suppression systems and some of them are non-lethal. My first duty assignment was at the Intelligence Center Pacific (IPAC) at Camp Smith, Hawaii and they installed a system in the computer room below us and on our deck as well due to all of the specialized analysis equipment we had installed. They wanted to test the system and asked for volunteers which I did. Quite startling when it first goes off and it spewed forth a vapor cloud that smothers the fire vice removing the oxygen. Interesting side affect is that it had the opposite affect that helium has when inhaled and the female sailor down in the computer room during the test did not like the sound of her very deep baritone voice after the test.
I have seen sub-floor CO2 systems replacing Halon but I am not versed in any breathable Halon systems. I’ll have to research.