Allergies

I know of allergies to foods and animals, I myself am allergic to certain cats. However having spent the last year or so in Canada and occasionally coming home to Ireland I've realised I'm allergic to my country or more so its climate. For years I've had problems with my sinuses which my mother has always blamed on the amount of milk I intake. However this was been ruled out. I spend 10 months in Toronto with nothing close to a cold but the second day I'm back in Ireland I'm going through a box of tissues a day (well almost) and when I return to the maple leaf city my symptoms leave. Explanation? Probably the damp climate in my homeland doesn't mix with my immune system which makes my homecoming slightly annoying.