[Drago]

We have Halon under our floors at work...our employees are warned to get out if it trips...they have 30 seconds to clear the room, but there are "override" big red push buttons in strategic locations in case they are still in the room...gives them 30 sec. more. I suspect enough oxygen displacement to suppress fire is enough to "suppress" humans also.

[Eagle Eye]

Halon disrupts the chemical reaction of rapid oxidation (fire) and doesn't depend on oxygen displacement.