A port of the polutionsolutions mod from way back in 0.18, see github for details

Quick FYI: This mod modifies several default Factorio mechanics to balance the pollution system. I’m operating under the assumption that the original developer made these changes for a reason; as such, I will not be reverting them unless several people ask.
Power & Environment: Solar panels produce 30kW instead of 60kW, and accumulators store 2.5 MJ instead of 5 MJ (both adjustable via settings). Trees now absorb pollution from the environment. Underground pipes have an increased range (5-20 tiles), allow items to pass through, and gain immunity to damage. Nearly all in-world entities receive immunity to the mod's custom "toxic" damage type, fire, and explosions. Player armour has partial toxic resistance (10-40% reduction depending on tier) rather than full immunity.
Please check the mod settings after installation; some of these are toggleable.

contributions: all contributions should be submitted in a Pull request on the github

original mod description below:
This makes Factorio more fun by turning pollution and combat into an interconnected system you actively engage with, instead of just tossing down laser turrets and forgetting about both. This minimalist mod stays close to the vanilla experience, adding only what's necessary to accomplish these goals.

The native life is capable of absorbing pollution. Destroying alien nests provides the red xenomass necessary to build pollution collectors. This gives a reason to go out and fight the aliens, something missing from the game after Alien Science was removed. In addition, turning pollution into electricity or oil products requires blue xenomass, acquired by killing alien creatures. Passive defenses are still an option, but with this mod, you're rewarded for investing in more complex systems.

Features
- You can collect, transport, and dump pollution into the environment, creating poisonous clouds to slow and damage attackers. Alternatively, you can spew it at attackers from Toxic Turrets.
- To get rid of pollution entirely, you can invest in Waste Treatment and Coal Liquefaction to turn pollution into oil products.
- Pollution processing unlocks around the same time as oil, giving you something tangible to work on while waiting for the many oil-based techs to research. Many of my friends who start Factorio for the first time get bored around that stage in the vanilla game. This solves that problem!
- The Toxic Incinerator is an early, simple reactor between fossil fuels and nuclear power. It allows new players to figure out how reactors work, without needing to deal with the complexity and extreme power output of nuclear reactors.