Bear in mind, this is a couple of guys who are tinkering with minecraft modding for the first time.If you can, make it so that the player/mod pack maker can configure which block produces what amount of pollution, plus if it's possible to detect when a block is "On" (aka actively doing something to cause pollution) bonus points.
Programming isn't an issue, but it'll take a while to get a grip on how mods are actually built. Fortunately there's a plethora of amazing resources out there to get started with.
Having said that, an ultimate goal is absolutely configurability.