Filters for Smoke Stacks

Add a Filters upgrade for Smoke Stacks, or a separated building for Filtered Smoke Stacks. It should recude the pollution, but suffer a reduced productivity and an increased manteinance cost.
I've no data to suggest a % pollution reduction by filters and so for productivity, but I find interesting the possibility to reduce the pollution, it could lead to a new production chain to construct filters, even a new mainteinance resource and building dedicated to filters.

There is already an Exhaust Scrubber in the game.

a scrubber is literally a smoke stack filter

I suggest to the developers that green plantings (trees, bushes...) reduce pollution.

its called EXAUST SCRUBBER. we have this

for those saying "we have the exhaust scrubber" that thing is only useful during and after late mid game
a small filtered smoke stack that produces sulfur at a 4 exhaust to 1 sulfur ratio but needing a cheap filter would be nice even if it only cuts the pollution effect by 20-50%
still worse than full exhaust scrubber but simpler and unlocked in the early mid game