I have lots of pollen allergies mostly to grass but also to olive trees and when I visited Italy a couple summers ago on vacation, I can say I didn't have too much problem. The climate was really hot though and it seems Italy is really short of places to get out of the heat but luckily we had our cruise ship to return to.
Climate change is expected to affect air quality through several pathways, including production and of allergens and increase dust.
It very much depends on exactly what you are alergic to. Also it would depend on the relative smog count compared to where you are now. Higher smog counts mean a negative impact. Lower is positive. What you are allergic to and its prevalence in teh area you are going to visit should have obvious implicaitons.
For safety bring your meds and have an extra rescue inhailer.
