[0.17.79] Pollution without a source

[ozfoxaroo]

It's no mystery that landfill tiles absorb zero pollution. https://wiki.factorio.com/Pollution#De-polluters

However I've encountered some pollution spreading across a landfill island where there is no source. Please refer to the attached image. It's surrounding a location where there is nothing whatsoever to generate any pollution. (Mostly accumulators and unused tiles).

It first appeared as one or two squares approximately in the area I've highlighted with a green border, when I was first creating the island and laying the accumulators. In the game hours that have elapsed (weeks in real time) this mystery pollution has expanded rather than dissipated. It now occupies the area in the white border. I expect that inevitably it will merge with genuine pollution from mining operations to the northeast.

Truthfully it doesn't bother me that much, but a friend recommended that I show this to the devs.

[Loewchen]

Post the save please.

[Rseding91]

Most likely you had pollution spread there and now it doesn't go away because you concreted over the land enough to lower the passive reduction to 0 or some insanely small value that will take half an hour to go away.

In any case, a save file is required to do anything about this.