Pollution absorption time?

[zOldBulldog]

I am quite puzzled. Most of my pollution was roughly 30% Boilers, 30% Steel Furnaces, 30% Electric Miners.

I just made a nuclear powerplant, and since I have auto-sensing circuits on my steam powerplant the water to the boilers shut down. Looking at the Production stats for Pollution I correctly see that the boilers are not generating pollution any more.

But when I look at my pollution cloud... it isn't shrinking?!!!

I am clearly missing some important concept. For example, is there an extended amount of time that has to pass before the pollution cloud shrinks? Or am I seeing some kind of bug and/or design flaw?

[BlueTemplar]

Well, it might take some time... you can check the exact values of pollution currently in the tiles using the show-pollution-values debug option (in map, after turning on the pollution display layer).

[bobucles]

The dark red pollution cloud has no upper limit. It counts ALL the pollution you've been building up the entire game. Once you get a good amount of filth rolling it can take RL hours (maybe even days) for a shut down factory to fully clear out.

[BlueTemplar]

Well, minus the pollution absorbed by terrain/trees/spawners...

[zOldBulldog]

The dark red pollution cloud has no upper limit. It counts ALL the pollution you've been building up the entire game. Once you get a good amount of filth rolling it can take RL hours (maybe even days) for a shut down factory to fully clear out.

That explains it. It has been about one IRL and the local cloud of the coal plant is still the same size, but... it *might* be one shade lighter, not sure.

[Koub]

You can show pollution values in debug menu to see the rate at which your pollution is absorbed.
Also remember that as long as you produce overall more pollution than the environment can absorb, your pollution cloud will continue to grow, even if you take measures to pollute less.

[Xeorm]

I looked at the values at one point for .17 for an early deathworld run. Wanted to see how long it'd take to empty the pollution to see if a start and stop method would work for keeping pollution away from biters. What I noticed pretty quick was that pollution didn't disperse much. 2% into adjacent areas really isn't much. So most of the pollution cloud stuck around the actual pollution producers, rather than being a more even spread. Took a good long amount of time for the pollution to all disperse. Didn't take much time either for the fainter bits to reach out. Didn't seem like a good overall strategy, but was nice to see visually.

[BlueTemplar]

Start and stop is equivalent to reducing your overall speed, but is probably worse, because a pollution pulse should travel farther before being absorbed than the same pollution released in a steady flow.
2% might not seem much, but it's per second !
And per neighbor, so up to 2 neighbors with less pollution in the "corners", "doubling" the spread... (and 4 in the "center")

[Ranakastrasz]

Start and stop is equivalent to reducing your overall speed, but is probably worse, because a pollution pulse should travel farther before being absorbed than the same pollution released in a steady flow.
2% might not seem much, but it's per second !
And per neighbor, so up to 2 neighbors with less pollution in the "corners", "doubling" the spread... (and 4 in the "center")

Pollution has no momentum. At best, if when activating everything, it is all running, and so overall pollution generated is higher, but with less ambient pollution and the fact it will spread back to the source too, and also fall off makes me doubt it would do much.

[BlueTemplar]

It does have kind of a momentum : it propagates at 2%/s/chunk when over 15.
I believe that it's this limit of 15 that is important : If you send a high-pollution pulse, it will more likely cross over this threshold on the edges of where the steady pollution cloud would be...

Consider for instance an hypothetical chunk with pollution absorption worth 14/s : if you send a 140 pollution pulse every 10 seconds, you'll have pollution spreading to nearby chunks, if you go at a steady 14/s, you won't !

In practice, you want to keep your pollution as steady as possible - each second where you don't have a spawner-free chunk absorbing pollution is extra pollution cleanup that you might have to do later...
(And sometimes you want to have spawners absorbing pollution : specifically it's better to have spitter spawners absorbing pollution than biter spawners, as spitters are much easier to kill, especially after 50% evolution !)

[Ranakastrasz]

Good point. It probably won't amount to much, but yea, I see what you mean