For workers in plants and on construction sites: tell danger, caution and safety instruction signs apart, read an accident prevention tag, and act on what signs and tags tell you.
Based on OSHA 29 CFR 1910.145 (general industry) and 29 CFR 1926.200 (construction) · about 4 min read
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Required signs and symbols must be visible at all times when work is being performed, and removed or covered promptly when the hazard no longer exists. A good practice is to report any sign that stays up after the hazard is gone, so people do not learn to ignore signs.
In general industry
The same colors apply to caution signs (yellow background, black panel with yellow letters) and safety instruction signs (white background, green panel with white letters). Caution signs are used only to warn against potential hazards or to caution against unsafe practices.
Your part: if a sign is hidden, missing, or warns about a hazard that is no longer there, tell your supervisor.
In general industry, all required accident prevention tags have a signal word and a major message. (These tag rules in 1910.145(f) do not apply to construction or agriculture; construction tags are covered on the next page.)
Signal word
The word that catches your attention: "Danger," "Caution," or "Biological Hazard," "BIOHAZARD," or the biohazard symbol. It must be readable from at least five feet, or farther when the hazard warrants.
Major message
The specific hazardous condition or the instruction for you, such as "Do Not Start." It can be pictographs, written text, or both.
Attachment
Tags are attached as close as safely possible to the hazard by a positive means, such as string, wire or adhesive, that prevents loss or unintentional removal.
Tags warn you about conditions, equipment or operations that are out of the ordinary, unexpected or not readily apparent.
A tag stays in use until the hazard is eliminated or the hazardous operation is completed.
Tags are not needed where signs, guarding or other positive means of protection are being used.
You must be informed of the meaning of the tags used in your workplace and the special precautions they call for.
Construction
Tags are a temporary warning of an existing hazard, such as a defective tool or piece of equipment.
A tag may not be used in place of, or as a substitute for, an accident prevention sign.
Your part: read the major message on any tag and follow it. A good practice is to leave a tag in place and report it, rather than removing it yourself.
DANGER tagMajor hazard: an immediate hazard that threatens death or serious injury. Used only in these situations.
WARNING tagOptional. A hazard level between Caution and Danger, used instead of the required Caution tag, provided it has the signal word "Warning," an appropriate major message, and otherwise meets the general tag criteria.
CAUTION tagMinor hazard: a non-immediate or potential hazard, or unsafe practice, with a lesser threat of injury. Used only in these situations.
BIOHAZARD tagIdentifies the actual or potential presence of a biological hazard, and equipment, containers, rooms, experimental animals, or combinations of these that contain or are contaminated with hazardous biological agents.
OSHA does not mandate tag colors, but it recommends red for Danger, yellow for Caution, orange for Warning, and fluorescent orange or orange-red for Biological Hazard.
Fact-checked against the regulation text on October 09, 2026. This certificate records completion of awareness training based on OSHA 29 CFR 1910.145 and 29 CFR 1926.200. It is not an OSHA card or license, and it does not by itself meet the training requirements of 29 CFR 1910.145(c)(1)(ii), (c)(2)(ii) and (f)(4)(v). In general industry, your employer must still instruct all employees that danger signs indicate immediate danger and that special precautions are necessary, instruct all employees that caution signs indicate a possible hazard against which proper precaution should be taken, and inform all employees of the meaning of the various tags used throughout the workplace and what special precautions are necessary. 29 CFR 1926.200 has no training paragraph of its own; in construction, your employer must still instruct each employee in the recognition and avoidance of unsafe conditions and the regulations applicable to their work environment (29 CFR 1926.21(b)(2)).
This guide explains the rule in plain words. Always read the regulation itself and your employer's site-specific procedures.