Question for Zombie/Romero/Night of the Living Dead afficionados

Regarding some NOTLD plot points that I haven’t been able to confirm through any plot synopses on the Web:

A.) First of all, please tell me if I’m remembering correctly- the zombification was the result of radiation from a meteor that fell to earth (?)

B.) According to the radio reports, were corpses revived around the world or only in the immediate area (Johnstown, PA or wherever it was)?

Thanks in advance.

I think it was all the unburied dead in the world.

Excellent. Thanks for the link, laura!