Pollution has long term effects. It's funny that now when we talk about nuclear we _care_ about the long term effects. Let's be honest, it's simply imprinted in our common consciousness as scary and that is that.
Besides, most reactors do not affect a large area unless they go wrong and the examples are quite far in-between.
The other thing about radiation is it's highly visible / detectable, tiny tiny traces of specific isotopes stand out clearly in a gamma spectrum from natural background. It's a lot more detectable than normal air pollution because the background is so low.
But it is not either or, but in addition.
The radius of effect may be small, but the duration is extreme.
Depending on the accident, the radius can be quite large. In Germany there are still areas where it is dangerous to eat mushrooms from the forest because of the radioactivity from Chernobyl.
And a study from the Max-Planck-Institute concludes that an accident is to be expected every 20 to 25 years.
An unnecessary one because of safer alternatives.
None of our technologies is flawless and on top of that there is human greed and incompetence. This means that even if we had clean nuclear energy, we would not be able to operate it faultlessly worldwide for a long time.
Or do you know an authority or a company that you would trust with this?
Besides, most reactors do not affect a large area unless they go wrong and the examples are quite far in-between.