ANSI Z35.1 the Specifications for Accident Prevention Signs, was an American standard that dictated the layout, colors and wording of safety signs in the United States. The standard is the first American standard that made specific demands for the design, construction, and placement of safety signage in industrial environments. The first edition was published in January 1941, and the fourth and final edition in November 1972. Changes in societal needs of signage, and further research into signage would result in the establishment of a new committee, the ANSI Z535 Committee on Safety Signs and Colors, combining the separate committees of Z35.1 - Specifications for Accident Prevention Signs, Z35.2 - Specifications for Accident Prevention Tags, and Z53 - Marking Physical Hazards Safety Color Code, resulting in a new combined standard, ANSI Z535.
Background
Initial groundwork for safety signs started in the 1910s, with Hansen's Universal Safety Standards (1913) called for a "universal danger sign" consisting of the word "DANGER" in white letters on a red field, and a "universal safety sign" consisting of white letters on a green field, for identifying exits and first aid equipment. Beyond this, various industries, including railroads, mines, and woodworking designed and implemented their own signage to protect workers and the public. Mine Signboards
In 1912 James W Stonehouse, a sign manufacturer in Colorado would advertise an early form of the iconic 'DANGER' sign, referred to as the 'universal danger signal'. It featured a red oval, on a black rectangle, with 'DANGER' in white letters. He would later devise and sell multiple uniform safety sign designs. Revised versions of these early designs would later become the basis of Z35.1.
In 1937, the National Safety Council identifying the need to improve workplace and industrial safety by setting standardized sign designs, to replace the haphazard sign designs that every workplace and industry was coming up with independently with set designs that workers could recognize in any workplace, on any jobsite in any industry. The NSC approached the American standards Association with the proposal, sponsored and led the project.
Even as early as the first edition, safety signs were recommended as a solution for when eliminating the hazard could not be achieved. Elimination or guarding against a hazard was a superior form of protection. While Z35.1 was intended for widespread use across all industries, there were exceptions. Z35.1 signage was not intended for motor vehicles, trains, maritime traffic, all of had specific regulations and standards of their own, such as the Manual on Uniform Traffic Control Devices for motor vehicles. Also excluded were safety posters, safety slogans, and bulletin boards, while safety related, fell out of the project scope, and were for clarity explicitly excluded.
Design
Z35.1 consisted of a common design through its four editions, consisting of three primary elements. Header panel - The top portion of the sign, consisting of a colored rectangle, containing the signal word. Signal word - A single word or phrase intended indicate sign purpose. Text message - The text conveying the hazard or other information.
Headers were always placed on top, with the text message located below the header. The design of headers, including distinct designs, such as the oval of 'Danger' and the solid black block of 'Caution' was intentional. This enabled non-English speaking persons to associate a design with hazard severity, and enabled color blind individuals to differentiate between header designs. Headers were not required on informational, directional and fire/emergency signs. How to include symbols on a sign was not elaborated on until the fourth, 1972 edition, with the exception of the Radiation sign.
Editions 1941 The first edition, published on 10 January 1941, the designs laid out in this edition would be the foundation for all successive versions.
Consideration was made for other forms of warning, such as tags, flags, and flare pots, but were set aside in order to complete the standard as quickly as possible.ASA. (January 10, 1941). Specifications for Industrial Accident Prevention Signs (Z35.1-1941). New York, New York: American Standards Association.
1959
Z35.1-1959 was the second edition of the standard, published in 1959. This would mark the first appearance of the ionizing radiation trefoil symbol in the Z35.1 standard, as well as the addition of a radiation warning sign design.ASA. (1959). Industrial Accident Prevention Signs (Z35.1-1959). New York, New York: American Standards Association.
1968 The third edition, published 18 September 1968, would see the addition of the slow moving vehicle emblem, and the Biological hazard symbol.USAS. (September 18, 1968). Specifications for Accident Prevention Signs (Z35.1-1968). New York, New York: United States of American Standards Institute. The symbol developed two years earlier by staff at Dow Chemical Company as a standardized symbol to warn of infectious substances, which it was adopted for this purpose by Z35 Committee through its inclusion in Z35.1.
OSHA adoption In 1971, OSHA adopted regulation §1910.145, which required that accident prevention signs in workplaces to comply with the standards laid out in ANSI Z35.1-1968 and ANSI Z35.2-1968 starting on August 31, 1971.29 CFR 1910.145 - Specifications for accident prevention signs and tags. (1974). (Scan of the Federal Register Vol 39 No 125 - 1974 - Pages 215-217.) Later, in 1979, OSHA would adopt regulation §1926.200 which specified accident prevention signs for use in the construction industry. The regulation varied a bit from §1910.145, by requiring a specific design for exit signs, using red letters on a white background, omitting mention of radiation and biohazard signs, tags, and symbols; as well as informational or 'Notice' signage and the slow moving vehicle emblem. However, it did state that signs and tags were required to comply with Z35.1-1968 and Z35.2-1968 in situations not covered by the rules in regulation.29 CFR Part 1926.200 - Accident prevention signs and tags. (1979). (Scan of the Federal Register Vol. 44, No. 29 - February 9 1979 - Pages 37-39.)
1972 The fourth and final edition of Z35, published on 16 November 1972 would see significant change in the standard, with it being nearly half the page count, and would a split of the standard, spinning off "informational and miscellaneous signs" and "directional signs" as a supplemental standard, later released as Z35.3-1973. Z35.1 would be overhauled, doing away with the suggested wordings, diagrams of the headers, charts of various sign dimensions. Signs were reorganized into a new 'Class' system, which assigned each type a class number. Guidance in the standard was made more general, leaving decisions to sign manufactures and workplaces. Clearer guidance on how to include a symbol with a sign's design was provided, however symbols, aside from five specific ones, were not provided, nor guidance on where to obtain or how to design symbols. A new 'Fire/Emergency' sign was designed, and references to exit signage were removed, instructing readers to refer to NFPA standards.ANSI. (November 16, 1972). Specifications for Accident Prevention Signs (Z35.1-1972). New York, New York: American National Standards Institute.
Split off from Z35.1, informational signs became the new Z35.3 Specifications for Informational Signs Complimentary to ANSI Z35.1-1972, Accident Prevention Signs standard. This standard also used the class system, with two classes: Class A, informational and Class B, Regulatory, which was new to the Z35 standard. The default design for Class A featured a "Notice" signal word on a blue header. The Class B design did not have a default signal word, which would be placed on a black header with white text. Directional arrows were also placed into Z35.3, but were no longer a standalone sign type. Most of the standard duplicated Z35.1-1972, such as sign placement, sizes, lettering, symbols and general layout of the signs.ANSI. (April 9, 1973). Specifications for Informational Signs Complementary to ANSI Z35.1-1972, Accident Prevention Signs (Z35.4-1973). New York, New York: American National Standards Institute.
End of Z35
The 1970s saw major societal changes in the United States, increased globalization and recognition of a non-English speaking workforce, and changes in legal liability that would put significant responsibility on manufacturers of products and workplaces to provide suitable warnings. These changes highlighted the limitations of the nearly 40 year old standard. Recognizing the need for change, in 1979, the Z35 Committee on Safety Signs was merged with the Z53 Committee on Safety Colors, to form Z353 Committee on Safety Signs and Colors. This new committee would unveil ANSI Z535 in 1991, updating three existing standards, alongside two new standards.ANSI. (June 1991). American National Standard for Environment and Facility Safety Signs (Z535.2-1991). Washington, DC: National Electrical Manufacturers Association. These new standards would provide more extensive guidance on the creation of text messages, more effective designs, and incorporating safety symbols.ANSI. (28 April 1998). American National Standard for Product Safety Signs and Labels (Z535.4-1998). Rosslyn, Virginia: National Electrical Manufacturers Association.
Wording limitations Z35.1 suggested easy to read and concise wording on signage. This often resulted in sign wordings that stated the general hazard very well, but often lacked information about how to avoid the hazard, specific nuances of the hazard, and consequences of ignoring the warning. Even more complex statements like "Caution - Operators of this machine shall wear snug fitting clothing - No gloves", still lacked any information on the possible consequences posed by wearing gloves, or loose clothing. The standard also provided minimal guidance on how to write a text message, with regards to concepts such as voice, length of messages, word choice, etc.; even after the removal of the lists of standardized text messages in the Fourth edition.
Bilingual limitations
In 1968, the year of the third edition of Z35.1, US exports and imports were valued at $45.5 & $45.3 billion respectively. By 1972, the year the fourth and final edition of Z35.1 was published, these values had climbed to $67.2 & $72.7 billion. By 1980, these had grown to $271.8 and $291.2 billion. During the 1980s, removal of trade barriers and free trade arrangements was an objective of the US Federal government. This would cumulate in the 1988 Canada–United States Free Trade Agreement. Trade with regions and populations that did not speak English was increasing, as were members of the workforce domestically who didn't speak English.
While a reason behind standardizing the designs and colors of signs in 1941, was to make signs understandable to non-English speakers, by being able to associate color and designs to severity of a hazard, this still left significant limitations. The hazards represented by "Danger" varied widely from electric hazards, to flammable or explosive materials, to toxic chemicals, which require different approaches to avoid harm. Z35.1 contained no requirement or even suggestion to provide signage in languages other than English, in a multilingual workplaces. Further, no instructions were ever provided on how to present a multi-language message with safety signage, such as English and Spanish, or what words should be used as the signal words in non-English languages. Often, the solution was to simply duplicate the sign in the other language, often placed directly below the English sign.