If you are talking about the corruption mechanic, where starting with your third town you start losing 10% (and +10% more for every town you found past that) of your resource income, culture output, and science output.
They only things that reduce the effects of it are special buildings, and certain effects on hero items (the item effects only work in the town the hero is in though).
The buildings are:
Courthouse (Late Medieval) for Resource income.
Conservatoire (Mid renaissance) for Culture.
And the Observatory (semi-late Industrial) for Science