By default, the entire planet is polluted over about 13 years.
It is designed to create a pollution threat to the player's settlement around 5 years after the start of the game.
Pollution spreads across 6 settlements of the watster pirate faction. You can stop the pollution by attacking and destroying that settlement.
If you destroy all the targets, you will see the ending where the entire planet is purified.
You can control everything in the options.
speed of spread of pollution
pollution spreading faction
count of pollution creating base
Requires: DLC Biotech