Not sure if this is what you're looking for, but if you open the console with F1, you can enter weather commands such as "weather fog 0" (without the quotes) which in the wasteland will make the haze disappear for the time being. If you're looking for something more permanent, I think the biomes XML has the code that makes the wasteland generally foggy. I may be wrong about this location. Whatever the case, I'm sure there's a way to modify your XML to disable the wasteland fog if that's what you want, you may be able to search the forums and find more info to help you.