Air 3 is a transmission exclusive to the Neurax Worm DLC and the Necroa Virus DLC.
Neurax Worm[]
It gives the Neurax Worm further survival in arid conditions.
Necroa Virus[]
It appears only after evolving Air 2, Blood 2, and Cytopathic Reanimation.
Symptom Combos[]
It is required, along with Cranial Elephantitis symptom, to produce the Cranial Dispersion combo and, thus, the Use your head achievement.