In Mira Grant's Newsflesh series, there are mentions of different areas having different "security levels", ranging from 1 to 10 (10 being safest). There are references to some of the levels explaining what they mean (I believe 10, 9, and 7 were explicitly described). Others are only alluded to. (They can decon you indefinitely for Level 2 exposure; they'll probably just shoot you for level 1).
Is there a list of what all the levels are?