@AlphaCentauri

No one wants to do a study on "What level of CO2 is painless for suicide"
--
What is death by carbon dioxide like?
At low concentrations, gaseous carbon dioxide appears to have little toxicological effect. At higher concentrations it leads to an increased respiratory rate, tachycardia, cardiac arrhythmias and impaired consciousness. Concentrations >10% may cause convulsions, coma and death.
--

@AlphaCentauri

and here is Carbon Monoxide.. isnt much better

the body KNOWS when it isn't getting oxygen and starts panicking.

https://www.pennmedicine.org/for-patients-and-visitors/patient-information/conditions-treated-a-to-z/carbon-monoxide-poisoning

@Kinnison
CO2 definitely causes panic. But low concentrations of CO are deadly without killing by suffocation. The body can't distinguish it from oxygen, and the CO binds much more strongly to hemoglobin than oxygen, so you can have full levels of oxygen present but still accumulate enough CO to die.

Someone I know nearly died of it in her home. She only felt sleepy. It was fortunate her son dropped by, realized she was too sedated and got her to help.

@AlphaCentauri

There never is, and never will be, a *humane* method of execution.