Q. (See last question) Why only (do we have to avoid a place that can bring tuma, and therefore we don’t stand under a roof) in Kidush Levanah and not while performing any other mitzva?

A. Igrois Moishe (O.H. 1: 144) questions why only in this particular mitzva we follow this custom and not anywhere else, where we rely on that most places are free of tumah. He claims that the reason mentioned by the Maharil is unknown to us. However, Sefer Kidush Levono (5: 1) explains that Kidush Levono is different since we receive the presence of the Shechina.

Horav Shlomo Miller Shlit”a added that the fact that this is a mitzvah that is done publicly on the streets where uncleanness is common creates a demand for additional vigilance and carefulness.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit’a