According to the Navy Uniform Regulations, the face must be clean shaven unless a shaving waiver is authorized by the Commanding Officer or higher authority. Mustaches are authorized but shall be kept neatly and closely trimmed, and the mustache cannot extend below the lip line of the upper lip, extend across the corners of the mouth or extend any further than 1/4 inch from the corners of the mouth. These rules exist because a study showed facial hair affects the proper fit of respirators. For more information regarding the study, contact Naval Safety Center Public Affairs at safe-pao@navy.mil. For more information regarding grooming standards, contact Chief of Naval Personnel Public Affairs at usnpeople.fct@navy.mil.