Safety while working in Teheran (Tehran)

Dear Friends,
I am from Ireland and new to the Teheran Forum. I have been offered a two year contract in Teheran working in the area of construction claims. The position starts in January Protected content . I was wondering what it is like to work in Teheran and particularly if it is safe there or have any of you ever encountered problems. I would very much appreciate your comments.
Paul