Must one be certain that the area around him is clean before saying a davar shebekedusha?

As we have learned, one may not be involved in a davar shebekedusha when there is tzoah in his daled amos or visual field. If a person would see tzoah by facing forward, it is not sufficient to turn his head in a different direction. Similarly, one may not daven or learn at night (when he cannot see tzoah) in a place where tzoah is visible during the day. Likewise, a blind person may not recite a davar shebekedusha in a place where tzoah would have been visible to a person who can see. If one is in an area where there may be tzoah, the poskim disagree about whether he is obligated to ascertain that none is visible. If a person did not check and later realized that there was tzoah in his line of sight, he is not required to repeat davening.

סימן עט ס"ק ג-ד ביה"ל ד"ה ומלפניו

What must a person keep in mind when he goes outside to say Kiddush Levana?

If there is tzoah behind a person, he is only obligated to be four amos away from it to say a davar shebekedusha. The same halacha applies if the tzoah is on his side. In this case, however, the Achronim say that one should turn away to make certain that it is behind him. The poskim disagree on how to classify tzoah which is moving alongside a person and heading in front of him further ahead. Some are stringent and treat it as if it is in front of him, while others disagree. All agree that if it is visible without his having to turn his head, it should be treated as if it is in front of him. In earlier times, it was common to have open sewage pipes running along the side of the street. The poskim caution that when one goes outside to say Kiddush Levana, he must be mindful that such pipes are not in his field of vision.

סעיף א' ס"ק ה'

When must a chazon pause in the middle of Chazoras Hashatz?

If tzoah is found in a shul in the middle of Chazoras Hashatz, the chazon must stop the repetition until the tzoah is removed. Even when it is not within his vicinity or visual field, the tzibur may not continue to answer Amen because it is visible to them or located in their vicinity. A similar halacha applies if mei raglayim is found in shul. Some say that if the mei raglayim is not in the vicinity of the chazon, he does not have to be stopped if he is unaware of its presence. According to this view, the lack of kavod hatzibur which is shown when the chazon is stopped is more of an issue than the Rabbinic prohibition against saying a davar shebekedusha in front of mei raglayim.

סעיף א' ס"ק ז

• The Torah states: “You shall cover your excrement, for Hashem your G-d walks in the midst of your camp, so your camp shall be holy”.  Based on this verse, Chazal explained that at a time when “Hashem is with you” (i.e. when you are involved in a davar shebekedusha), you must be in a state of holiness and cleanliness.

• A person’s camp or place is defined as the four amos in which he finds himself.

• Aside from not saying a davar shebekedusha within daled amos of tzoah, it is also forbidden if there is tzoah in one’s visual field.

• Does a curtain serve as a proper partition?

• Does the adjoining room have to be clean before a davar shebekedusha can be recited?

• Can a davar shebekedusha be said if there is an odor emanating from another room?