It had to do with atomic warfare... someone used like, an atom bomb,  that poisoned the Earth's atmosphere. All the humans started dying off except this one little girl who hid under her kitchen table with sheets over the table like a fort... she survived because she only drank water and ate food that didn't have the poisoned powder (caused by the atom bomb) The girl's sister covered her in sheets and took her to a neighbors house when she knew she was going to die...

Anybody know what I'm talking about???????

I remember that book .... I don't know the name of it. I do remember that the surviving generations start to mutat, growing fur to protect that from the radiation.

  You can try over at www.abebooks.com   They have a section called Booksleuth and the forum members there are out of this world when it comes to figuring out those books we just can't remember!