intro image

High voltage … biohazard … wet floor … radioactive materials. Safety symbols like these rely upon consistency and bold, graphic impact to warn against specific hazards and personal injury. A revised American National Standard from the National Electrical Manufacturers Association (NEMA) provides general principles for the design, evaluation, and use of safety symbols, as well as a procedure to evaluate a given image’s effectiveness in communicating its intended message.

Originally published in 1991 and revised in 1998, the new revision, ANSI Z535.3-2007, American National Standard Criteria for Safety Symbols, incorporates several significant changes. The safety alert symbol has been harmonized with color alternatives specified by the International Organization for Standardization (ISO). In addition, Annex A of the document now includes illustrations of the standard’s principles and guidelines. Finally, safety symbol examples have been moved from the normative body of the standard into an informative annex (Annex C), and a wider variety of symbols related to file and other safety conditions are now included.

Many safety symbols warn against permanent conditions, but similar visual cues can be used to warn of temporary hazards such as barricades, construction areas, and maintenance activities. NEMA’s revised ANSI Z535.5-2007, American National Standard for Safety Tags and Barricade Tapes (for Temporary Hazards), establishes a communication system that uses different signal words and colors to distinguish between levels of hazards.

The revised standard defines the requirements for the design and use of safety tags and barricade tapes, establishing a uniform and consistent visual layout for safety information. In the interest of harmonization with international standards, the document now permits the use of different colors with the safety alert symbol.