how is it repulsing him? either it's radiation pressure, where's he's getting fried, or it's air pressure, which would be at perhaps a million degrees if he's near ground zero, and if he's small enough to not get immediately killed by radiation the air is gonna be inflicting actual damage to him, especially when super-heated and moving very quickly. extreme brownian motion
Because it's a comic book movie and so it takes the physics that apply to things like ants and why they don't die from huge falls and the like and bumps them up to comic book standards for shit like this.
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Seplito Nash, Smelling Like the Vault since 1996 Step FOUR! Get Paid!