I think that pollution is a term clear enough. No need to debate that there is no pollution because of the term, any more than debating that the Arctic areas cannot be melting because Wikipedia isn't reliable enough.
One can of course go and see things with the naked eye.....comes as a shock to many that got thrown off by maneuvers like that one.
BTW, since you mentioned what is added to crops, you just entered my field.
Nitrate, yes, but you need to balance it with phosphate and Kalium (Potassium). N-P-K.
Nitrate will enhance growth, which will, by the way, tie up charbon. After all, the valuable part in plant tissue is C.
You will need more N if there is much C in the ground, since they hook up.
With organic growing however, that is not so marked. But since you still need N, you need to grow N-binding plants to make the N or you. (Alfa-Alfa, Clover, Peas, etc). Brilliant. You use the sun's energy to harness both N and C out of the atmosphere through plants.
And then on to pollution...
If you grow up with it and know little else...then what? It's normal.
If you don't, and later go and see it every now and then, it's a shock!
Drive to a city of millions, and you will see the sphere of polluted air way before you spot the buildings. Depending of landscape of course.
You will have no visibility compared to relatively clean air.
I have seen a coastline from some 200 miles. Try that in LA.
And other pollution? Try drinkable water to undrinkable for instance. very many man-made examples I''m afraid...