Here are my serious thoughts about Ground Zero.

In Chapter 7 part 3 Michael makes homemade chloroform and uses it to knock out some Biters so they could be tagged with locators. The Chloroform did not work as well as it was suppose to but did work for a short time. This implies to me that the zombies breath to a certain degree. If this is the case then it stands to reason that if the air at Ground Zero is so bad then there also should not be very few if any zombies there since they could not breath there either.

To recap: bad air at ground zero makes me think that there may not be any zombies there.

Bad thought: Maybe there is another kind of special zombie we have not meet yet that just lives at ground zero. Scary thought!

The Might Atomic Hamster has spoken