What can you do???? Seems obvious to me- DON'T BE THERE! Working in NYC (or any other large city for that matter) is, in my opinion, a choice against one's own survival for many reasons.

Dirty bomb is really easy- don't worry much about it. While radioactive contamination of your person isn't a *good* thing, it's not automatically fatal. It's not even as bad as so-called-Journalists would say. They think you'll die if you look at the radioactive element in a smoke detector.... (a bio-bomb on the other hand could be a major problem)

My biggest nuke concern is a single EMP burst high overhead. Now THAT would do some widespread economic damage plus our veneer of civilized behavior would rupture and then cause physical harm.
Are your electronic survival devices stored EMP-protected???
(Unclassified sources suggest the Iranians have been practicing for an EMP strike. Makes sense- all it takes is ONE warhead to hurt us on an enormous scale.)