How does pollution occur?

[mrmichaeln]

I know factories cause pollution, but when I don't have any factories, pollution still occurs. Why is that?

[planetfall]

Pollution is either building pollution, i.e. coal plants, factories, offshore, or population pollution. See editor for more details on amount of pollution associated with each city improvement. Note some improvements decrease population. Decrease but do not eliminate.

== PF

[Catt]

Expanding on PF's explanation -- certain city improvements (factories, coal plants, etc.) cause pollution -- they generate a specific number of "pollution triangles" that appear in your city view screen in the lower left (below the luxuries). Additionally, each population point above 12 creates one "pollution triangle." The pollution triangles represent the probability that a random city radius tile will be hit by pollution each turn -- more triangles = more likely to get hit with pollution in that city.

Mass Transit System (available with Ecology) eliminates all but one of the pollution triangles caused by population. Recycling Centers (available with Recycling) eliminates all but one of the pollution triangles caused by city improvements. So, with both MTS and RC, a city could be size 40, with every possible polluting improvement and still have only 2 pollution triangles. Meanwhile, a city without a MTS could be pop 15 and have 3 pollution triangles.

Catt

[Nick727]

I have never had a city size 40, I thought 30 was biggest a city could get.

[WarpStorm]

In theory, you could have a size 72 self supporting city (on railroaded wheat floodplains). Before PTW, you could have a 256 population (you can in the editor but it will starve down to). Before 1.29f of Civ3 you used to be able to pump population into the thousands.

[mrmichaeln]

Thanks all for the info.

I agree with nick727 that in "practice" size 30 or so is about as big a city as I'll ever see in my games, but it's nice to know theoretically what the maximums are, and why.