[quote=Polyphemus]
This sounds a lot more interesting than some of the other tired apocalyptic scenarios. Count me in.Just out of curiosity (and you don't have to answer if it's plot-critical or whatever) but what cities aside from Dallas managed to construct appropriate safeguards?
[/quote]

Heh, thanks for the interest. I'm currently undergoing several technical difficulties with making this a viable apocalypse (whether it's the oceans or a volcano is up for debate at this point, I'm a bit too perfectionist), but the unbreathable atmosphere will remain a constant. And as for the cities, these are the known ones.
Couple in Russia
Three or four in the US
Two in Germany
One in Switzerland
Couple in China
One in Japan
Canada has one
The Scandinavian countries actually banded together and made a city entirely underground- like a vault
Nobody is sure why
They don't talk to anybody

Anyway, Saudi oil princes and such have one
It's smaller and more luxurious
And while it isn't confirmed, everyone thinks Israel had one

As far as if anyone wonders why the US has the most cities, it's simply because I live in the US and am more familiar with it.