The danger and effect of Z-Density on combat depends on the following factors. Note that these are not simply adding or subtracting a straightforward number from a random roll to determine the danger, but act together to produce a separate model of combat and risk for each survivor in a squad, with each member of the squad also being affected by the rest of the squad.
- Speed. Faster moving survivors will spend less time in a block and be less exposed to danger. Remember that every item carried will have an effect on speed.
- Fear and Fatigue. Scared or tired survivors will be more likely to make mistakes which get them injured and make them less effective at killing zeds.
- Hunger and Thirst. High levels in these will make the survivor less effective.
- Weapons and Skills. A well-armed and skilled survivor is more likely to avoid injury. Melee combat is more dangerous than using Firearms.
- The composition of the Squad. A larger squad will have more effect but may also attract more attention. One character might be able to slip past zeds easier than ten. A member of a well-armed squad will be better protected even if the survivor is unarmed or unskilled.
- Z-Density. A block contains an actual number of zeds, but this is expressed in Z-Density rather than a number. For the purposes of visualising danger, you could assume that there is about one zed for every meter if the Z-Density is at 100%. That doesn't mean that every meter of the block will contain a zed - they could be grouped or scattered - but it gives you an idea of the numbers. A small block will therefore reach maximum Z-Density much faster. Some of the larger blocks could absorb so many zeds that they never become dangerous. Note that smaller blocks tend to be in the center of the city, with some very large blocks out in the countryside.
The Z-Density expresses a quantifiable number of zeds correlated with the size of the block, and that Z-Density, in combination with all the factors above, can result in injury or death.
Basically, spend more time in a dangerous block and your survivors will be more at risk.