Factorio Forums

I think this might be a bug of sorts, I got this polluted square that does not disappear. If you look at the save file it's north-west to the upper base, just over the small stretch of refined concrete. The pollution was caused by a flamethrower killing worms, I think I saw some trees burning there as well.

Keep in mind that concrete doesn't absorb pollution, and if there's no tiles or entities in that chunk that can absorb pollution, a minimal amount will remain for eternity (to my knowledge, at least).

EDIT: Wiki numbers say landfill doesn't absorb either

Thanks for the report. Because you've paved over the chunk (mostly) and it has no trees you've reduced the effective pollution absorption of the chunk to -0.1 per minute. It has 4 pollution on it which means it will take 40 minutes to clear out.

Haha cool!