Mahouka Koukou no Rettousei - Nyuugaku-hen - Vol. 3 Ch. 17 - Subjugation

[MangaDex]

 

[Lexical]

Fun fact: Removing everything but nitrogen in the terrorists’s masks would’ve been completely painless and loss of consciousness or at least higher cognitive abilities would’ve ensued within a minute, possibly even s little as several seconds depending on the purity of the nitrogen. Since normal sea-level air is 78% Nitrogen + 1% other gases, our physiology can’t tell the difference when it’s missing that 21% oxygen. Furthermore, because it can still displace carbon dioxide, the familiar burning sensation that come with holding one’s breath for too long would not occur. They’d be out like a light without even realizing anything was wrong. There’s a great video by Smarter Everyday Why you should put your mask on first that’s shows him trying out a high altitude simulation, it’s worth checking out

Tldr those blokes wouldn’t have known what hit them.