I am the regional safety manager for our company (which is a large one). We require, and I beleive it is an OSHA requirement but not sure, nozzles that reduce the outlet pressure to 30 psi. We tell employees not to blow themselves down but we know it happens. Thus the reduced pressure nozzles. To Cody's point, i recently confiscated 3 reduced pressure nozzles that had been modified to provide the full 120 psi at the outlet.
I do it my slef at home. As has been mentioned, common sense is the key.