What is the primary means of mitigating mild or severe symptons of nerve agent exposure?

It's a three-step procedure.

First, put the victim's protective mask on him.

Next, inject THE VICTIM's autoinjector kits - one kit at a time, injecting the atropine first (small autoinjector) then the 2-pam chloride (big one). Don't use your kits on a victim because you might need them yourself. If the victim needs other first aid, administer it at this time.

And finally, get the victim away from the nerve agent.