A type of safety sign, warning signs are visual communication tools used to indicate workplace hazards that can cause a serious injury or even death if not avoided. These signs are regulated by authorities such as OSHA and ANSI, which provide information about the design of warning signs, the format and wording of messages, placement of the signs, and more.
These signs are used to warn workers against hazards such as hot surfaces, arc flash and shock, certain biohazards, close clearance, ice and snow hazards, combustible dust, and more. Warning signs are also used to communicate safe practices such as keeping hands out of machinery, pinch points, not accessing authorized personnel only areas, no smoking, etc.
ANSI Z535.2-2011 (R2017) Section 8 requires the wording of safety signs, warning signs included, to be concise and easy to read. The text letters on the signs should be big enough for a person with normal vision as well as corrected vision to read the safety sign message from a safe viewing distance from the hazard. The height of signal word letters should be at least 50% greater than the height of a capital ‘H’ in the sign legend.
You should take several factors into consideration when determining the placement of your warning sign. As per ANSI, a ratio of 25 feet of viewing distance per inch of text is necessary to create favorable viewing conditions.
Warning and other safety signs should be placed at a safe viewing distance from the hazard so that the viewer has sufficient time to prepare without being exposed to the hazard. The signage should be in a well-lit area and be clearly visible without any objects, emissions, etc. obstructing the view.
Information related to safe viewing distance of safety signs can be found in ANSI Z535.2-2011 (R2017), Sections 11 and 12.
Usually constructed from rigid materials like aluminum, warning signs can easily be mounted to walls, doors, posts, and fences. These can range from 3.5”x5” to 24”x30” or even greater in size and can carry comprehensive safety messages. Warning signs are installed at a safe viewing distance from the hazard and often require installation by drilling screws on pre-punched holes.
Generally smaller in size, labels are usually made of paper, polyester, or vinyl and are flexible. Unlike signs, these are usually applied closer to the hazard on points of contact, on surfaces, etc. Warning labels stick to the surface and do not require any drilling.
Warning labels are more economical than warning signs. While the former is perfect when you need your safety message to go where the hazard does, such as warning labels on containers carrying dangerous materials, the latter is required to identify workplace hazards such as machinery, forklift areas, electrical units, and so on.
The OSHA Standard 1910.145 describes warning tags as tools used to represent a hazard level between that identified by "Caution" and "Danger". These carry a signal word "Warning" and an appropriate major message that communicates the specific hazard or the safety instruction. Information about the placement of these tags, readability, etc. is also provided in the standard.
Warning signs are also covered in ANSI Z535.2011, which provides eight classifications of safety signs and details about the design, size, and viewing distance of these signs. These specifications are taken into consideration in OSHA standards.
OSHA warning signs are usually orange in color, while ANSI warning signs feature the signal word “Warning” on an orange background along with the safety alert symbol, which is a triangle with an exclamation point in the middle. Additionally, ANSI, and at times, OSHA warning signs carry pictograms to convey the safety message more effectively.