29 C.F.R. § 1910.145
(a) Scope.
(c) Classification of signs according to use—(1) Danger signs.
(2) Caution signs.
(10) Slow-moving vehicle emblem. This emblem (see fig. J-7) consists of a fluorescent yellow-orange triangle with a dark red reflective border. The yellow-orange fluorescent triangle is a highly visible color for daylight exposure. The reflective border defines the shape of the fluorescent color in daylight and creates a hollow red triangle in the path of motor vehicle headlights at night. The emblem is intended as a unique identification for, and it shall be used only on, vehicles which by design move slowly (25 m.p.h. or less) on the public roads. The emblem is not a clearance marker for wide machinery nor is it intended to replace required lighting or marking of slow-moving vehicles. Neither the color film pattern and its dimensions nor the backing shall be altered to permit use of advertising or other markings. The material, location, mounting, etc., of the emblem shall be in accordance with the American Society of Agricultural Engineers Emblem for Identifying Slow-Moving Vehicles, ASAE R276, 1967, or ASAE S276.2 (ANSI B114.1-1971), which are incorporated by reference as specified in § 1910.6.

Figure J-7—Slow-Moving Vehicle Emblem
(e) Sign wordings.
(f) Accident prevention tags—(1) Scope and application.
(2) Definitions. Biological hazard or BIOHAZARD means those infectious agents presenting a risk of death, injury or illness to employees.
Major message means that portion of a tag's inscription that is more specific than the signal word and that indicates the specific hazardous condition or the instruction to be communicated to the employee. Examples include: “High Voltage,” “Close Clearance,” “Do Not Start,” or “Do Not Use” or a corresponding pictograph used with a written text or alone.
Pictograph means a pictorial representation used to identify a hazardous condition or to convey a safety instruction.
Signal word means that portion of a tag's inscription that contains the word or words that are intended to capture the employee's immediate attention.
Tag means a device usually made of card, paper, pasteboard, plastic or other material used to identify a hazardous condition.
(4) General tag criteria. All required tags shall meet the following criteria:
(i) Tags shall contain a signal word and a major message.
(8) Biological hazard tags.
(ii) The symbol design for biological hazard tags shall conform to the design shown below:

Biological Hazard Symbol Configuration
(9) Other tags. Other tags may be used in addition to those required by this paragraph (f), or in other situations where this paragraph (f) does not require tags, provided that they do not detract from the impact or visibility of the signal word and major message of any required tag.
Appendixes to § 1910.145(f), Accident Prevention Tags
Appendix A to § 1910.145(f)—Recommended Color Coding While the standard does not specifically mandate colors to be used on accident prevention tags, the following color scheme is recommended by OSHA for meeting the requirements of this section: “DANGER”—Red, or predominantly red, with lettering or symbols in a contrasting color. “CAUTION”—Yellow, or predominantly yellow, with lettering or symbols in a contrasting color. “WARNING”—Orange, or predominantly orange, with lettering or symbols in a contrasting color. “BIOLOGICAL HAZARD”—Fluorescent orange or orange-red, or predominantly so, with lettering or symbols in a contrasting color.
Appendix B to § 1910.145(f)—References for Further Information The following references provide information which can be helpful in understanding the requirements contained in various sections of the standard: 1. Bresnahan, Thomas F., and Bryk, Joseph, “The Hazard Association Values of Accident Prevention Signs”, Journal of American Society of Safety Engineers; January 1975. 2. Dreyfuss, H., Symbol Sourcebook, McGraw Hill; New York, NY, 1972. 3. Glass, R.A. and others, Some Criteria for Colors and Signs in Workplaces, National Bureau of Standards, Washington DC, 1983. 4. Graphic Symbols for Public Areas and Occupational Environments, Treasury Board of Canada, Ottawa, Canada, July 1980. 5. Howett, G.L., Size of Letters Required for Visibility as a Function of Viewing Distance and Observer Acuity, National Bureau of Standards, Washington DC, July 1983. 6. Lerner, N.D. and Collins, B.L., The Assessment of Safety Symbol Understandability by Different Testing Methods, National Bureau of Standards, Washington DC, 1980. 7. Lerner, N.D. and Collins, B.L., Workplace Safety Symbols, National Bureau of Standards, Washington DC, 1980. 8. Modley, R. and Meyers, W.R., Handbook of Pictorial Symbols, Dover Publication, New York, NY, 1976. 9. Product Safety Signs and Labels, FMC Corporation, Santa Clara, CA, 1978. 10. Safety Color Coding for Marking Physical Hazards, Z53.1, American National Standards Institute, New York, NY, 1979. 11. Signs and Symbols for the Occupational Environment, Can. 3-Z-321-77, Canadian Standards Association, Ottawa, September 1977. 12. Symbols for Industrial Safety, National Bureau of Standards, Washington DC, April 1982. 13. Symbol Signs, U.S. Department of Transportation, Washington DC, November 1974.
Note: All dimensions are in inches.
[39 FR 23502, June 27, 1974, as amended at 43 FR 49749, Oct. 24, 1978; 43 FR 51759, Nov. 7, 1978; 49 FR 5322, Feb. 10, 1984; 51 FR 33260, Sept. 19, 1986; 61 FR 9239, Mar. 7, 1996; 76 FR 24698, May 2, 2011; 76 FR 44265, July 25, 2011; 78 FR 35566, June 13, 2013]