(Mishnah): One must distance carcasses, graves and a tannery from the city by 50 amos (because of the bad smell they produce).

One may only build a tannery to the east of a city (as the east wind is gentle and will not bring the bad smell into the city).

R. Akiva: He made build it on any side of the city, aside from the west (as the Divine Presence is to the west), and he must distance it by 50 amos.

(Gemara) - R. Abahu citing R. Yochanan: In explaining R. Akiva, (he may build a tannery even close to the city) if the skins are already thick, (as they do not give off a bad smell).

One of the House of Yanai: In explaining R. Akiva, in the other directions, he may build a tannery in a place where the smell no longer reaches the city (which is 50 amos), but to the west, he may not build it at all.

Support (Beraisa - R. Akiva): He made build a tannery in any direction at a distance, except for the west, as the wind is constant.

R. Mana would often walk with men with skin disease. Abayei told him only to walk on the west side of the person, as on the east side, the wind will blow on him from the diseased man.

(Mishnah): One must distance the flax-soaking pit from vegetables; leek from onions and mustard from bees.

R. Yosi permits the mustard.

(Gemara) - Beraisa: One must distance onions from leeks.

R. Elazar son of R. Shimon permits it.

R. Yaakov ben Dusai: From the Mishnah and the Beraisa we learn that just as leeks should be distanced from onions, so onions should be distanced from leeks (as they both damage each other).

R. Abahu citing R. Yosi ben Chanina: (Why must mustard be distanced from bees?) When bees eat mustard, they have a sharp taste in their mouths and they eat the honey to remove the taste.