Supernaut asked about the details of pollution, particularly as it pertained to research... So... the following is the mathematics of how pollution is computed in Civ 2. It may be difficult to readily follow at first, but here it goes (at the end of the equations is a Key which defines the variable names).
Pollution icons consist of two sources, added together... Population Pollution (PP) and Resource Pollution (RP).
PP = (CP * TM) / 4 (round down)
TM is further modified by this:
|Auto||+1||Mass Production||+1||Plastics||+1||Sanitation not discovered||+1||Environmentalism||-1||Solar Plant||-1||Mass Transit||TM=0|
RP = (SP / RPD ) - 20
TP = RP + PP (round down)
P = DL * (A / 2)
RN = Random Integer between 0 and (256 - P)
If RN < (TP * 2) then you get 1 pollution within the city radius
|TP||Total Pollution Icons||it is the # of pollution icons you see in city status|
|CP||City Population||Size of city|
|RPD||Resource Pollution Divisor|
|DL||Difficulty Level||0-Chieftain, 1-Warlord, 2-Prince, 3-King, 4-Emperor, 5-Deity|
|A||Number of advances since 4000 BC||this EXCLUDES the advances you started with!!!|
|RN||Random Number||an integer|
As you can see mathematically, after you discover the 102nd advance at deity, you are guaranteed to get pollution every turn, even if you have only a single pollution icon (the yellow triangle) in your city status. This translates to Future Technology 15.... after that, even one pollution icon in a city status screen will yield one polluted terrain.
As everyone doubtless knows, there are 87 normal advances, assuming zero at the start. If you had 5 starting advances, then the last discoverd advance (assume stealth) would be number 82, which is used in the pollution calculation (variable A). This yields a lower probability of pollution in a city that has a pollution icon. It also means that 100% probability of pollution will not occur for a single pollution icon until the 20th Future Technology is discovered at Deity.
So as you can see, pollution probability is affected by the total number of advances that you discover during the game. The starting techs do NOT count to this total, thus your probability of pollution will be lower at any given number of advances you have discovered.