1)    Washing which is not for pleasure, but only to remove sweat, (especially in a time or place when they sweat a lot), is permitted during these days. He should use cold or lukewarm water and not hot water. It is correct to wash one limb at a time, and not the whole body at once. (Shu”t Igros Moshe Even Ha’ezer 4,84 Shevet Halevi 7,77)

2)    One who immerses himself in a Mikveh every day before praying, may do so even during these days. (ibid)