Mega Pollution on Ultagigantic maps

[johnc214]

I've played several games before and never seen this issue. I'm heading toward a finish in 100 years (game year 2108) and all of a sudden, 7 to 10 tiles around every city on the map get pollution. I have the Global Matter Decompiler and all 160 of my cities have all the available anti-pollution devices. My total pollution is around 35,000. When I get the pollution, there's no message in the message box. Just large numbers of squares all over the entire map (not just my territory) go black with pollution.
What's going on? I can't seem to make it not do this. I've replayed adjusting the settings and it happens around 2108 to 2110 every time.
Any ideas? I've never seen this before, and I've had a lot higher pollution levels. And the fact I'm getting no message sounds like a bug in the program? I use modswapper on Ultagigantic setting.
Thanks!
Johnc214

[Martin Gühmann]

What mod do you use John.

The pollution values are determined in advance.txt, government.txt and pollution.txt.

-Martin