After spending a lot of time in London, I am glad Americans don't embrace diesel like they do in Europe. The place just reeks of diesel and 2 strokes.
Or is your complaint that you prefer the smog from gas over the smog from diesel?
Regardless there are a lot of great arguments against diesel in this thread (e.g. increased cost Vs. MpG, maintence cost + additional car cost Vs. gas, and so on), this argument ("the smog!") doesn't really feel like one of them.
I've spent a lot of time in London AND American cities, and neither are pleasant. I count the days until most cars are electric and we can breath again. Even hybrids seem like a marked improvement over gas or diesel (in particular during traffic jams).