They used a mask rather than the more appropriate method which would be to use a sealed chamber that was forcefully evacuated of oxygen and replaced by nitrogen the way the suicide pods are supposed to function.

The problem with a mask is it can’t be a perfectly sealed system. The issue with the execution from a logistical standpoint was the redneck engineering they employed and not the actual science behind nitrogen hypoxia.

Please don’t come at me, I’m not making a value judgment about the use of the death penalty, I’m just explaining the issue with their shoddy ass methodology.

Edit: accidentally a word.

Edit #2 (YouTube Link): Here is some additional information about why a gas mask is an ineffective and dangerous way to conduct an execution via nitrogen hypoxia from Dr. Philip Nitschke, a leading advocate of the right to die movement and an expert in the field of voluntary euthanasia. He personally examined the execution method being used in Alabama, and told them he felt it would be ineffective for many of the same reasons stated above.