I don't know this for sure, but pollution is random - however I think it pops up again somewhere else once you've cleared a spot, so the faster you clear it - the faster it pops up somewhere else. And that gets cumbersome later in the game as you are building more polluting stuff.
Because it will just pop up again somewhere else once it is cleared, so spending extra turns to clear it takes workers away from doing other productive things.
This is
untrue!
There is a chance, each turn, of pollution popping up within the city radius. how big this chance is, depends on how many
pollution triangles the city generates.
Some improvements and pop above size 12 generate these
pollution triangles.
It is possible a city will never have pollution even if it is generating 40 triangles.
And there is a chance a city will have pollution each turn, even if it is generating only 1 triangle.
Cleaning the pollution or not, has no effect on the chance of more pollution popping up somewhere else, but
not cleaning the pollution
will effect global warming.
Here's one trick - I used to get pretty anal about getting the pollution cleaned up, so I'd stick enough workers on a polluted spot to clear it in one turn. That costs a lot of worker efficiency considering it takes 3 or 6 or more turns to clear the stuff depending on what tile it's on.
If your city is not affected by one tile being unusable (ie: there's another available tile that the citizen using the now polluted spot can move to to minimize lost productivity and/or starvation), then let one worker take the maximum turns to clear it.
And - especially, if a tile is polluted that doesn't affect your cities current efficiency status (ie: no citizen is working the tile) - let it sit until that city grows in population and you need that tile.
As stated above the more polluted tiles there are, the bigger the chance of global warming. So it is in your interest to clean pollution as fast as possible, to keep the number of polluted tiles as close as possible to zero!
On higher difficult levels, this can be somewhat of a problem because the AI doesn't clean up pollution very quickly. So you'll have global warming thx to teh AI. The best cure for that is to conquer the AI.
Also, if you have placed your cities with any kind of efficiency in mind about tile-usage, the there should no longer be any tiles in your terrain that are not worked by any citizen.
The biggest polluters are pop above size 12. A size 13 metro will generate 1 pop-based pollution triangle. A size 21 metro will generate 9. Building a
Mass Transit System, will reduce this to 1 triangle, no matter how many pop.
The triangles generated by city improvements are not effected by the
Mass Transit System, instead they are effected
Recycling Center, witch works the same way.
A metropolis with both transit and recycling will generate 2 pollution triangles. It can't get lower than that.
The only exception to these rule is the
Iron works small wonder. The IW triangles are counted seperately from both pop, and improvement pollution.
Cities at size 12 or below will never generate pop-pollution. If you also never build any polluting improvements, you'll never have pollution at all.
As for the amount of workers you need... I usually enter the modern age with over 100 workers, on a standard size map. And that is just left over from the rail-roading effort.
I usually don't build additional workers anymore, except when I'm still conquering (assuming I fail to capture enough slaves) or when I'm relocating pop to crate instant max sized metro's.
However, I don't normally have a lot of metro's, if at all.
Code:
Polluting city improvement:
Improvements :number of
:triangles
_______________________________________________________
Coal Plant : 2
Factory : 2
Manufacturing Plant : 2
Research Lab : 1
Airport : 1
Offshore Platform : 2
Commercial Docks : 1
:
Small Wonders :
_______________________________________________________
Iron Works : 4
Airfields (C3C) don't generate pollution. Thus the only function of Airports is to create vet air units. My advice would be to select one or a few cities that specialize in making air units. And only build an airport in those cities. This will also save you additional upkeep cots, if the cities can be specialized enough, these will also not need barracks, if they don't build land units.
When building a factory, or when building a hospital and letting the city grow beond size 12, consider if the increase in producting will actually be enough to shave a turn of the
units per turn output of whatever unit you plant to specialize the city for. Example: A MA will cost 120 shields. a city producing 20 uncorrupted base shields per turn , thus 40 with both a factory and a plant, will produce one each 3 turns. If letting the city grow from size 12 to 20 will only add 8 more shields, its production will go up to 56. That is still 3 turns for a MA, so why bother to let the city grow?
. I've heard people say this before, but it never actually happened to me.
