Newer systems like the ones mentioned above are designed to reduce the amount of oxygen in the room to around 12% (down from around 21%). That's low enough to

Newer systems like the ones mentioned above are designed to reduce the amount of oxygen in the room to around 12% (down from around 21%). That's low enough to extinguish fires, but allows people to safely evacuate and prevent people from suffocating if they're incapacitated.