It seems most answers have been along the lines of "Hitler had a soft spot in this regard because of his experiences in WW1", but it doesn't seem this interfered with the methods of the "Final Solution". I remember reading a reprinted article in The War Illustrated describing the inadequacies of artificial rubber at the time for keeping molecules of poison gas at bay, thus the Germans, now without any colonies in Africa at their disposal, were at a disadvantage as far as capacity to create masks for the allied retribution if they did attack. Verify?
As a follow-up question, I would also ask why didn't the Soviets use poison gas?
Previous answers can be found here https://www.reddit.com/r/AskHistorians/comments/1tetpp/why_didnt_nazi_germany_use_chemical_weapons_in/
Follow up: is there any indication that Hitler's own experiences in WWI may have impacted the decision not to use gas on the battlefield in WWII?
Follow up question: I heard that the Germans haf a special gas (a nerve agent) that was extremely potent that wouldn't be affected by gas masks. Whereas the allies did not. Is this true? AND if so, how large was the gap? Could it have changed conditions on the eastern front?