“The best method of execution is to simply put the perp in an airtight chamber and remove the air. It works like a charm and produces a euphoric feeling in the perp.
The euphoria occurs as the brain becomes oxygen starved. Excess CO2 causes pain so removing the CO2 removes the pain of asphyxiation.
Removing the air from an air tight chamber would be to put the perp in a vacuum. Hardly a painless death.