[arkades]

The resultant 12% oxygen is 60% of normal atmospheric air. It's still breathable, if you're an average healthy person with healthy cardiac and pulmonary function, sitting at rest - but it's not healthy, it's enough that you're going to start seeing systemic responses. The reduction in partial pressure of oxygen being sucked into the lungs will also cause an increase in the partial pressure of carbon dioxide and inert gases.

I think the concern likely comes from:

-Folks that are of poor cardiac function are going to be evacuating, meaning increased cardiac demand under stress, while being somewhat oxygen-starved. This could tip some folks into an acute episode that otherwise wouldn't.

-Folks that are of poor oxygen function, who are borderline hypoxemic to begin with. Think folks with chronic obstructive pulmonary disorder: about 5% of your employees aged 55-65 will have it.

You won't suddenly kill a building full of people. I'm guessing the evacuation rush is to make sure they're not liable for unnecessarily sending a couple to the hospital.

[mveety]

Even if you were healthy you’d be in bad shape. I know from flying your mind goes quick when oxygen levels go down. You feel drunk and get a bit euphoric and refuse to acknowledge you’re in any trouble at all. Low oxygen, especially if the environment is dangerous or requires a clear mind and/or quick action, is a killer.

[regularfry]

Possibly more importantly, the "venting" is not what you'd call a gentle breeze. "Explosive atmosphere replacement" is a better description. Solid things will go airborne at speed.

[owenversteeg]

Huh, so I was curious and looked up demonstration videos. Some of them looked similar to an indoor hurricane and some of them looked like a gentle breeze. The classroom-style (small room with a few Inergen bottles) demonstrations had the biggest effect and the actual datacenter tests just looked like a small breeze. Maybe in an actual datacenter the Inergen:open space ratio is substantially smaller than demonstrations in a small room?

[linker3000]

Won't somebody think of the hard drives.

[dharmab]

Also: Folks that are already suffering from smoke inhalation due to a fire. Unlikely since the halon systems are pretty good at reacting, but still possible.

[arkades]

A good point. I feel a bit foolish for overlooking it.

[darkpuma]

>The resultant 12% oxygen is 60% of normal atmospheric air.

To put that in perspective, that's like being sent to the top of Pikes Peak (4.3km / 14,000') in seconds. Pilots flying that high in unpressurized aircraft are required to have oxygen masks. Most people will develop altitude sickness when rapidly subjected to that.

When you consider the potential for stress or panic in this kind of scenario, hypoxia emerges as a very real threat even for the young and healthy.