Uh, maybe this is a dumb question. But, why is it that in GFIII, when Zaza offers Michael a cigarette, he refuses. I mean, is this supposed to be part of his character, a changed man? Or is it health reasons? It seems unlikely, b/c in 1979 everybody was still smoking. And, could it be because Pacino himself had quit before the start of shooting?

Is the answer in the commentaries perhaps?