Signs are an important part of work area safety that protect workers, visitors, and the general public. If there is a potential hazard, signs must be visible at all times.
OSHA Standard 1926.200(a) Signs (…) required (…) shall be visible at all times when work is being performed, and shall be removed or covered promptly when the hazards no longer exist.
Signs are the warning of hazard, temporarily or permanently affixed or placed, at locations where hazards exist. All safety signs should be visible and legible. If an active sign is vandalized, becomes rusted, or is coming off the affixed location, it must be replaced immediately. Any sign that is no longer relevant should be covered or removed immediately.
Danger signs indicate that there is an immediate threat and special precautions are necessary. Red should be the main color on the top of a black and white Danger sign.
OSHA Standard 1926.200(b)(1-2) Danger signs shall be used only where an immediate hazard exists… Danger signs shall have red as the predominating color for the upper panel; black outline on the borders; and a white lower panel for additional sign wording.
Don't assume everyone is aware of clear and present danger, signs are important! Use Danger signs to mark hazardous areas to prevent potential serious injuries to employees and others that could be in the area at any time.
Caution signs warn against potential hazards or caution against unsafe practices, that if not avoided, could result in minor or moderate injury. Caution signs are yellow and black to ensure they are easily visible.
OSHA Standard 1926.300(b)(2) Caution signs shall be used only to warn against potential hazards or to caution against unsafe practices… Caution signs shall have yellow as the predominating color; black upper panel and borders: yellow lettering of "caution" on the black panel; and the lower yellow panel for additional sign wording. Black lettering shall be used for additional wording.
Warning signs indicate a potentially hazardous situation.
Safety instruction signs are used to provide information, procedures or instructions.
OSHA Standard 1926.200(e) Safety instruction signs, when used, shall be white with green upper panel with white letters to convey the principal message. Any additional wording on the sign shall be black letters on the white background.
Notice signs are often blue and provide information that is considered important but not directly hazardous (example: security or hygiene).