Quoting an article about safe use of nitrogen, it is odorless, tasteless, and colorless. At extreme low levels of oxygen, nitrogen can cause unconsciousness and death in seconds and without warning.
I’m not talking about the chimps who executed this guy designing the system, I’m talking about qualified scientists designing it. The beauty is, you don’t need a medical doctor to monitor oxygen levels if you rapidly remove the oxygen and add nitrogen. Send in slightly chilled nitrogen and the air will rise above it. Relief valve up top spits out the oxygen. Homeboy is unconsciousness before he realizes why the air just got cold.
The freediver will hold his breath confidently for four minutes, exhale, suck in pure nitrogen, and be out in a breath or two.
I agree that the state does lie and incompetently kills people, but we can design a system that does it well. I just don’t agree they should ever use it.