Here, we’ll continue to talk about things that have to be set up at least 50 amot (cubits) away from the city. A person has to keep all dead animals or graves at a distance. A tannery, which is a place where they would make leather, has to be set up at least 50 amot away from the nearest city. All of these things we mentioned give off a bad smell and could bother people. We are concerned that the wind will carry the smell to a city. If it is 50 amot away, the smell will disperse before it reaches the city.
There is an additional law regarding the tannery, the burseki (tannery): you may set one up only in the eastern part of the city. If it is in the eastern part of the city, there is no concern that the wind will carry the odor, because the eastern wind, which blows from east to west, is mild and will not carry an odor with it. So, you are not allowed to set up a tannery unless you are on the east side of the city, in addition to the 50 amot we mentioned above.
He says that a 50-amot radius is okay and that the smell will not reach the city. But for a separate reason, you are not allowed to set up a tannery on the western side of a city. This western-side restriction has nothing to do with odor. It says that we're nervous that many people in Eretz Yisrael face west, toward the western wall, toward the Beit HaMikdash, when they pray. That is considered to be the spot of the Shechinah (Divine Presence). It is where the Shechinah dwells. Therefore, it is sort of improper to set up a tannery at that spot toward which people are facing, even if it is 50 amot away from the city. And that is what we say. Of course, he agrees that, in any event, the tannery has to be at least 50 amot from the city. But in addition to that, it cannot be on the west side, toward which people would normally pray.