I think this is a very interesting subject where far too little good research has been done. Consider the vast reductions in non CO2 emissions from automobiles in the last thirty years and compare that to the relatively incremental improvements in aviation.
Anecdote: I live about three miles from the ramp at KABQ. On a fairly calm night full of cargo aircraft, I can clearly smell the distinctive aroma of Jet A emissions on my front porch. A single grossly polluting automobile passing a hundred feet from my door is rarely bad enough for me to get a whiff of hydrocarbons.
So while I think the global warming/greenhouse gas emissions aspect needs lots more good research, I think it is fairly obvious that aircraft operations dump loads of smog forming pollutants into the areas surrounding airports. That opinion is of course based on anecdote and could be completely wrong.