Is a blessing recited upon taking safety precautions:[1]

Whenever one does something to remove danger, a blessing is not recited. [Despite this, when a roof is obligated to have a fence or guardrail placed around it, some Poskim rule that a blessing is to be recited, as will be explained in Chapter 3 Halacha 5.[2]]

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[1] Admur 181:2; Rambam Brachos 6:2; 11:4; Rashba Toras Habayis Bayis 6 Shaar 5; M”A 4:13; Peri Megadim 4 A”A 13; 157 Pesicha; Elya Raba 4:8; Likkutei Sichos Vol. 2 Parshas Ki Seitzei; Sefer Shemiras Haguf Vihanefesh [Lerner] 218:3; Mavo Chapter 4

Custom of Tzanzer Rebbe: See Sefer Hoil Moshe Teshuvos 9 and Taamei Haminhagim that the Tzanzer Rebbe once said a blessing of Vinishmartem upon not eating Maror one Pesach Seder due to doctors’ orders, however, many have recounted this as false, including the Tzanzer Rebbe of today [See Sefer Shemiras Haguf ibid p. 47]

[2] The reason: The reason that a blessing is said upon building a fence to prevent danger, despite the ruling that a blessing is never made over an action done to prevent danger, is because the Mitzvah of making a fence is in addition to the Mitzvah of preventing blood from spilling in one’s home, and hence it deserves its own blessing. The command to make a fence is in addition to the command to remove danger from one’s home, as one can remove the danger through other ways such as by elevating the ground so the roof is not 10 Tefach high, or by making the roof be in a slanted form of which is not obligated in a fence. Thus, from the fact that nevertheless the command is to specifically make a fence we see that the fence is additional aspect to that of the danger, and in fact its reason has nothing to do with danger, and rather the aspect of danger is commanded in the negative command of “do not spill blood in your house”. A proof to this differentiation is that the Rambam rules that a Mitzvah and its reasoning are never counted as two different Mitzvos, and thus from the fact that both avoiding danger and making fence are counted as two different Mitzvos proves that the reasoning behind making a fence is not because of danger. [Rebbe Likkutei Sichos Ki Seitzei 2 p. 89 and Vol 9 footnote 28 and Vol. 19 footnote 48; See Minchas Chinuch 546:2; Chayeh Adam 15:24; Emek Sheila Eikev Sheilasa 145:17; Peri Megadim 4 A”A 13; 157 Pesicha]