Q. A new liquid product that can be sprayed onto cloth face masks is about to become available. The spray coating using electrostatic charges, captures COVID-19 molecules on the surface of the mask, preventing them from being inhaled into the lungs or exhaled into the environment. This greatly increases the effective protection of the masks. Can a mask be sprayed on Shabbat?
A. On question 2220 we wrote; "Poskim permit using on Shabbos suntan and insect repellent liquids, oils and lotions, when they are thin, of low viscosity, and of flowing consistency. They also should not be for medicinal use. (Piskei Teshuvos 327: 1).
Horav Shlomo Miller’s Shlit’a opinion is that it is permitted to spray repellent on clothing also, even if it has some aroma, since the main intention is not to impart fragrance, but to repel insects." See also question 1770.
However, regarding the spray in question, Horav Shlomo Miller's Shlit'a opinion is that one should avoid spraying the mask during Shabbos as the prohibition of 'tikun mana' or changing and fixing an object may be involved, since the intention is indeed to make the mask a better type of filter.
The Rov added that a nurse or one attending several patients, may spray on one self and clothing with disinfectant spray, to avoid carrying viruses from one patient to another.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller and Horav Aharon Miller Shlit'a