[O6ret]

So why is it “horrible”?

[TangoLimaSierra]

So why is it “horrible”?

My question, too.

[TheDon]

Agreed. The atmosphere is about 78%. The condemned will pass out then die when the oxygen is replaced with nitrogen.

Make each death row cell air tight, then the condemned can be executed in the cell during the night while they sleep, never knowing which night is their last.