Danger, Warning or Caution - Choose the Right Safety Sign ... OSHA Sign specifications also show the following: • 1910.145 (c) (1) (ii): All employees shall be instructed that danger signs indicate immediate danger and that special precautions are necessary. • 1910.145 (c) (2) (i): Caution signs shall be used only to warn against potential hazards or to caution against unsafe practices.