I updated the code with the Z check for poisoning for all three types of swamp now: Land, Static, and Added. (My own types for keeping track, nothing official.) End result: Players walking in structures in Papua no longer get poisoned.
Current Status of script:
Staff members will be poisoned. There is commented out code to not poison staff members. Remove the comment marks and adjust the staff levels. Or have staff wear swamp boots. :>
Dead players are not poisoned.
Mounted players do not have their mounts poisoned. The rider can still be poisoned though, unless they're wearing swamp boots. (I plan to change that to riders getting poisoned regardless of wearing swamp boots while mounted, but not poisoning mounts.)
Creatures in the swamp do not get poisoned. Sorry. This script is for players only. Way too many creatures would have to be made poison immune otherwise.
Currently this makes ALL swamps poisonous. Probably even ones made up of home tiles. Keep this in mind.
Code posted and file attached are synced. Both include all the latest code.
Please report any new slowdowns this script may cause. So far I haven't found any in my testing, but it has been rather limited.
Player height (Z) now matters, if they are over a land, static, or added swamp, they will not be poisoned. Both posted code and attached file updated.
And thank you to everyone. ^.^