*Posted on Factorissimo2 Mods Discussion, copied here for mods developers 'heads up'; not sure if it really is a bug.
https://mods.factorio.com/mod/Factorissimo2/discussion/687ae28c89e974d8acc7d53c

Hello!
First off, I want to preface this as, perhaps, not a bug; more of a mod-to-mod feature/functionality not applying. I totally understand if it's going too far to request this feature tweak.

I see that there's a pollution mask created in the world (ex.: Nauvus) where your polluting factorissimo structure is when you're looking at the map, with the pollution visible.
Now, I also play with Bob's Mods; the building in question is the Greenhouse. This building will polute '-10' during operation, and it's quite visible when you build greenhouses outside of the factory buildings.

I'm wondering if the exterior pollution mask (ex.: where a factorissimo building is placed on Nauvus) can also subtract pollution if the 'net pollution' within the interior map space becomes negative?