I really like the story and I'm totally hooked by Kallie, but... honestly, the Author hasn't solved some substancial inconsistencies yet, which are:
- the food problem;
- skin, hair and eyes protection against fog;
- the "airing out" clothes problem.
Since they left the burger joint, there is no way they would have found any food at all. Period.
Secondly, they should have worn some balaclavas and ski masks. There is no way they can protect hair and eyes with what they have now. I might add that Kallie is wearing ballerina shoes.
Then, "airing out" clothes. They simply aren't able to to do it.
Lastly, as someone has already wrote, why didn't they move as soon as the fog thinned out?
Hopefully, the Author will decide that they will find more suitable masks and move to some Campus' cafeteria or so.