Breathe means to take air into the lungs and expel it. Nails do not have the ability to take in air through the nail plate.  Cosmetic scientist Doug Schoon explains that “100% of the oxygen needed by the nail matrix to create a new nail plate comes from the blood stream and 0% comes from the outside world”.  In conclusion, you don’t have to take your nails off to breath because your nail plate receives oxygen through the bloodstream.