Ujm – in bavel they used to make their sukkos on their rooftops; also, in very concentrated jewish areas like ghettos, or new square, kiryas yoel, or even bnei brak and parts of yerushalayim, there’s really no concern, but living among goyim can make people nervous if they’re in such a precarious situation. Like i said above, this heter would not apply to many people who are able to have sukkos in their backyards or terraces, which i would say is about 40% of Yiddishe families
