Prohibitory safety signs serve to prevent risks and compliance with regulations, certain prohibitions or restrictions on inappropriate or hazardous activities in the area, workplace, machine, equipment, system or technology. Signs need to be installed on visible and easily recognizable places. It is necessary to place them in all workplaces, access roads and doors into a space with a corresponding ban.

Prohibition marks have a circular shape with a black pictogram on a white background, a red border, and an oblique strip; the black pictogram, the red border and the oblique strip occupy at least 35% of the mark area.