OSHA Caution Signs vs Warning Signs: Key Differences

This article is part of the Print Pro AZ OSHA and ANSI safety sign series. Start with the pillar guide: ANSI Z535 Safety Signs: Complete Standards Guide.

Per ANSI Z535, CAUTION (yellow, black text) signals a hazard that may cause minor or moderate injury. WARNING (orange, black text) signals a hazard that could cause death or serious injury. Choosing the wrong signal word understates risk, confuses workers, and creates liability if someone is hurt after reading a sign that did not accurately describe the severity.

The sign says CAUTION. The hazard causes a fatality. The company's attorney is now explaining to a jury why the word was chosen. This scenario plays out in OSHA investigations and product liability cases more often than safety managers want to admit.

The distinction between CAUTION, WARNING, and DANGER is not aesthetic. ANSI Z535 established these signal words with specific severity definitions. Using CAUTION when the hazard warrants DANGER is a compliance failure. Using DANGER on every sign diminishes the signal and creates sign blindness. Getting the word right is the entire job.

This guide explains exactly what differentiates each signal word, the color requirements under ANSI Z535, the liability implications of choosing wrong, and how Print Pro AZ helps you stock the right signs for every hazard level.

What Are the Three ANSI Z535 Signal Words?

ANSI Z535 defines three signal words for safety signs, listed in order of decreasing severity:

DANGER -- Indicates a hazard that, if not avoided, will result in death or serious injury. The word "will" is intentional -- this is not a conditional statement. The hazard is immediate and the outcome is certain if exposure occurs. DANGER is used only for the most severe hazards.

WARNING -- Indicates a hazard that, if not avoided, could result in death or serious injury. The word "could" distinguishes it from DANGER. The hazard is serious, but the worst outcome is not certain. There may be factors that reduce the likelihood of the worst case.

CAUTION -- Indicates a hazard that, if not avoided, may result in minor or moderate injury, or property damage. A CAUTION hazard is real but not life-threatening. A slip-and-fall on a wet floor, a pinch point on a conveyor, a hot surface that could cause a burn.

A fourth signal word, NOTICE, is also part of the ANSI Z535 family. NOTICE (safety blue header) is used for important information that is not safety-related -- no injury or property damage potential. "Do not use this door after 10 PM" is a NOTICE, not a CAUTION.

Color Requirements for Each Signal Word

ANSI Z535.1 defines exact color values for each signal word. The colors are not arbitrary -- they create visual pattern recognition so workers identify severity level at a distance, before they can read the text.

Signal Word	Header Color	Text Color	Background
DANGER	Safety Red (Pantone 186 C)	White	White message panel
WARNING	Safety Orange (Pantone 152 C)	Black	White message panel
CAUTION	Safety Yellow (Pantone 109 C)	Black	White message panel
NOTICE	Safety Blue (Pantone 294 C)	White	White message panel

The Safety Alert Symbol (exclamation point inside an equilateral triangle) appears on DANGER, WARNING, and CAUTION signs that warn about personal injury hazards. It is placed in or next to the header panel alongside the signal word. NOTICE signs do not use the Safety Alert Symbol.

Inspection Tip: Safety yellow (CAUTION) and safety orange (WARNING) look similar in poor lighting or on faded outdoor signs. OSHA compliance officers look for color fidelity, especially on outdoor signs that have been exposed to UV for several years. If the WARNING orange on your sign has faded to look like CAUTION yellow, that is a citation waiting to happen. Print Pro AZ's UV-resistant vinyl labels maintain color fidelity significantly longer than standard stock.

How to Choose the Right Signal Word

Use the probable severity of the worst likely outcome as your decision rule:

Use DANGER when:

Direct contact will cause death or life-threatening injury
The hazard is energized at lethal voltage
Exposure to a chemical will cause immediately dangerous to life and health (IDLH) conditions
The fall distance is lethal
No protective equipment makes the hazard survivable with normal exposure

Use WARNING when:

The hazard could cause death or serious injury under certain conditions
The hazard is dangerous but survivable with quick response
PPE reduces the risk to acceptable levels but the hazard itself is still severe
The outcome depends on exposure time, response speed, or other variables

Use CAUTION when:

The hazard will cause minor or moderate injury at worst
The hazard causes property damage but not personal injury
The risk is a slipping, pinching, tripping, or minor burn hazard

Use NOTICE when:

No injury potential exists
The sign communicates operational instructions or policies
The sign protects equipment, not people

The most common mistake is using CAUTION for hazards that warrant WARNING or DANGER. This happens for two reasons: CAUTION feels softer and less alarming (which can seem preferable for routine maintenance areas), and facility managers who did not receive formal training often default to CAUTION as a catch-all. Neither reason holds up under OSHA review.

What Happens If You Use the Wrong Signal Word?

Using an undersized signal word creates three problems:

1. Compliance violation. OSHA 29 CFR 1910.145 requires that accident prevention signs be appropriate for the hazard. A CAUTION sign on a hazard that warrants DANGER can be cited as non-compliant with 1910.145(c) and 1910.145(d).

2. Failure to communicate. Workers use signal words to make quick decisions about PPE, approach distances, and work procedures. A CAUTION sign does not trigger the same protective behavior as a DANGER sign. If a worker enters an area labeled CAUTION and is killed by a hazard that should have been labeled DANGER, the sign failed its primary purpose.

3. Liability exposure. In personal injury litigation, signal word selection is discoverable. An attorney will ask who selected the word, what training they had, and whether the selection was consistent with ANSI Z535 criteria. An employer who used CAUTION on a lethal hazard because it "seemed fine" has no credible defense.

The same logic applies in reverse. Overusing DANGER on minor hazards creates sign blindness. Workers learn to ignore DANGER signs if they appear on every door and trash bin. Reserve it for hazards that genuinely warrant it.

Where Do CAUTION and WARNING Signs Belong?

Typical applications by signal word:

CAUTION -- common applications:

Wet floor or slip hazard (temporary)
Low clearance overhead obstruction
Forklift traffic area (low-speed, controllable)
Hot surface below the burn threshold for serious injury
Personal protective equipment required (where PPE makes the hazard manageable)
Eye wash station location

WARNING -- common applications:

Pinch points on machinery where serious injury is possible
High-temperature surfaces that can cause severe burns
Energized equipment below the DANGER threshold (e.g., equipment at 120V where NFPA 70E tables put it in a WARNING category)
Chemical exposures that could cause serious, though not immediately fatal, health effects
Fall hazards at heights where injury is likely but not universally fatal

DANGER -- common applications:

High-voltage electrical equipment (50V and above per NFPA 70E approach limits)
Confined spaces with IDLH atmospheres
Energized electrical equipment above DANGER threshold in NFPA 70E tables
Chemical exposures at IDLH concentrations
Fall hazards at heights where a fall is likely to be fatal

Print Pro AZ carries pre-printed CAUTION, WARNING, and DANGER labels in our electrician labels collection, all on UV-resistant vinyl with multiple size options. Our custom label service lets you specify the exact hazard message, signal word, and size needed for your application.

ANSI Z535 vs. OSHA 1910.145: Understanding the Difference

OSHA 1910.145 is the federal regulation. ANSI Z535 is the consensus standard that defines how to comply. They are not identical:

OSHA 1910.145 only uses DANGER and CAUTION as safety signal words (plus SAFETY INSTRUCTION). It does not include WARNING.
ANSI Z535 includes DANGER, WARNING, and CAUTION as the three-tier hierarchy.
OSHA compliance officers treat ANSI Z535-compliant signs as meeting 1910.145 requirements.
If you use WARNING signs, you are going above and beyond 1910.145 (which does not define WARNING) while meeting the more complete ANSI Z535 standard.

For practical purposes: use ANSI Z535 as your design guide. It is more precise, more current, and more complete than 1910.145. You will exceed the OSHA floor while meeting the industry standard that drives design, inspection, and litigation.

FAQ: Caution Signs vs. Warning Signs

What is the difference between a CAUTION sign and a WARNING sign? CAUTION indicates a hazard that may cause minor or moderate injury or property damage. WARNING indicates a hazard that could cause death or serious injury. WARNING is more severe. The color difference makes them distinguishable at distance: WARNING is safety orange, CAUTION is safety yellow.

Can I use WARNING and CAUTION signs interchangeably? No. Each signal word has a defined severity level under ANSI Z535. Using CAUTION where WARNING is appropriate understates the risk and may constitute a violation of OSHA 1910.145. The selection must be based on the worst probable outcome of ignoring the sign.

Does OSHA require WARNING signs? OSHA 29 CFR 1910.145 does not specifically define "WARNING" as a required signal word. ANSI Z535 does. OSHA compliance officers use ANSI Z535 as the accepted industry standard. In practice, using ANSI Z535-compliant WARNING signs is consistent with OSHA requirements and provides better hazard communication than the older 1910.145 two-tier system.

What color is a CAUTION sign? ANSI Z535 requires CAUTION signs to use a safety yellow header panel with black text. Safety yellow is defined in ANSI Z535.1 with specific color values (Pantone 109 C is the common match). The message panel is typically white or light background with black text.

What is a NOTICE sign and when should it be used? NOTICE (safety blue header, white text) is used for important operational or informational messages that have no personal injury or property damage potential. Examples: "Do not leave equipment running unattended," "Authorized personnel only," "Return all tools to this cabinet." It is not a safety warning -- it is information. The Safety Alert Symbol is never used on NOTICE signs.

Three Takeaways and Next Steps

CAUTION, WARNING, and DANGER have specific severity definitions under ANSI Z535. They are not interchangeable and selecting the wrong word creates real compliance and liability risk.
Color is the first communication -- safety red, safety orange, and safety yellow must be accurate and visible. UV-faded signs lose their signal.
ANSI Z535 goes further than OSHA 1910.145 in defining signal words. Follow Z535 -- it is more precise and is the standard that drives inspection and litigation.

Shop pre-printed OSHA CAUTION, WARNING, and DANGER labels on UV-resistant vinyl for every hazard level. Browse the collection or call Brent: (602) 649-5305

Brent Hanke | Print Pro AZ | (602) 649-5305 | b.hanke@printproaz.com Brent Hanke is the founder of Print Pro AZ, supplying NEC-compliant labels to contractors across the country. Last Updated: 2026-09-24