Safety Signs

Around the turn of the 20th century, scattered literature began to appear regarding the role of signs in accident prevention. As the industrial movement marched forward, there was a recognized need for an organized effort towards accident prevention, a major part of which included the development of a standard approach to safety signage. The National Safety Council charged the American Standards Association (ASA) with the responsibility of developing standard designs and colors for signs aimed at providing a system to quickly and effectively alert workers to a potentially dangerous situation. In the 60's, the scope was expanded to standardize the incorporation of pictorials on safety signs. Although many organizations and independent companies have developed product safety signs and label guidelines specific to their needs, the most generally accepted criteria for safety signs are currently published by the American National Standards Institute (ANSI) designated as standards Z535.1 through Z535.5. The information that follows in this article is presented to give the reader an introduction to selected aspects of signage.

What is a safety sign? ANSI defines a safety sign as a visual alerting device which advises the observer of a potential hazard. The sign should therefore be eye catching and clearly convey the intended message. Safety signs may consist of signal word, a message panel, and/or a pictorial symbol that are displayed in specific colors to alert and inform observers to take precautionary or other appropriate action in the presence of potential hazards.

A signal word is a word that shall indicate the relative degree of severity of an immediate hazard. For uniformity, signal words are associated with specific colors. The five colors defined by ANSI and their associated signal word are shown below. DANGER indicates an imminently hazardous situation which, if not avoided, will result in death or serious injury. This signal word is associated with the color red and is to be limited to the most extreme situations. Potentially hazardous situations that could result in death or serious injury are indicated by the word WARNING and associated with the color orange. CAUTION is indicative of a potentially hazardous situation which , if not avoided, may result in minor or moderate injury. CAUTION may also be used to alert against unsafe practices and is associated with the color yellow. Green is used for the identification of safety equipment, first aid, or emergency egress locations. Blue is the color used to convey safety information on signs and bulletin boards. The colors purple, white, gray, black, and brown have not been assigned specific applications as of the 1991 revision of the ANSI Z535.1 standard.

You will notice that some signal words are spelled out in white and others in black. The idea is to choose a color combination where the signal word clearly stands out against the background. Therefore, words positioned on a dark background are white and those against a light colored background are black. The signal word panels shown are the result of a significant amount of research designed to determine the optimum combination of colors for maximum impact and clarity to the observer. The same principle applies to the message panel. This is the portion of the sign used to identify the hazard and to indicate how to avoid it. Like signal words, standards specify guidelines for the letter style and size to be used. The intent is to relay the warning message in a clear, concise, and easily readable format. In addition to written messages, pictorials, such as the ones shown below, are also often incorporated into safety signs to display an image that is easily recognizable and universally understood.

The design of safety signs can vary depending upon the requirements of the organization. They are typically rectangular and can be oriented either vertically or horizontally. The Department of Transportation (DOT) uses signs that are diamond shaped placards for placement on road vehicles as shown below. The signs shown are for three different materials, all of which display the pictorial to warn that each shipment is potentially flammable. In addition to the written description which indicates the potential hazard, the location and extent of the red danger color is varied to further distinguish between the materials. Some organizations also incorporate a numeric classification system to indicate hazard severity. Refer again to the DOT placards and note the number in the lower corner. For DOT, the system ranges from 1-9 while the National Fire Protection Association (NFPA) uses a 0-4 ranking.

The development of safety signs has evolved over the past century and certainly a one page article does not begin to do it justice. We hope this brief overview has served as an introduction to draw your attention to the main aspects of safety signs. For further details or discussion, please contact us directly.