⚡ TL;DR — Quick Summary
- Blue means mandatory, an instruction that must be carried out. Yellow means warning, a hazard that is not likely to be life threatening.
- Red has three different meanings depending on the shape: a red circle with a slash means prohibited, a red oval with black text means danger (life threatening), and a solid red background means fire equipment location.
- Green means emergency information, the location of first aid, exits or assembly points.
- Colour and shape work together, not colour alone. The same colour can mean different things depending on the sign’s shape and layout.
- These colours are set out in AS 1319-1994, Safety Signs for the Occupational Environment, reaffirmed in 2018 and still the current Australian standard.
Blue means mandatory. Yellow means warning. Green means emergency information. Red is the one that catches people out, because it means three different things depending on the shape of the sign, prohibited, danger, or fire equipment location.
Safety signs use colour as the first layer of communication, before anyone reads a word. This guide breaks down exactly what each colour means, why red covers three separate categories, and where the whole system comes from.
Related → Guide to OHS Safety Signs | Workplace Safety Signs and Symbols
Quick Answer: What Each Safety Sign Colour Means
| Colour | Meaning | Example |
|---|---|---|
| Blue | Mandatory, must do | Hard Hat Must Be Worn |
| Yellow | Warning, be aware | Caution, Slippery Surface |
| Red (circle and slash) | Prohibited, do not | No Smoking |
| Red (oval, black rectangle) | Danger, life threatening hazard | DANGER, High Voltage |
| Red (solid background) | Fire equipment location | Fire Extinguisher |
| Green | Emergency information, safe condition | First Aid, Assembly Point |
Blue Safety Signs, Mandatory (Must Do)
Blue means mandatory. A blue sign indicates a specific instruction that must be carried out, most commonly PPE requirements such as “Hard Hat Must Be Worn,” “Hearing Protection Required” or “Eye Protection Must Be Worn.” Under AS 1319, mandatory signs use a white symbol on a blue circular background, with black lettering on white where wording is used.
Blue means: must do. Not “do not,” and not “be aware,” specifically an instruction that has to be followed.
Yellow Safety Signs, Warning (Be Aware)
Yellow means warning, a hazard or hazardous condition that is not likely to be life threatening, such as a slippery floor, moving machinery or an overhead powerline. Warning signs use a black pictogram inside a yellow triangle with a black border.
Yellow is used because it is one of the most visible colours to the human eye against most backgrounds, which is also why it is the standard colour for hazard tape, hi-vis clothing and forklift beacons. It signals “pay attention” rather than “stop” or “this will kill you,” which is reserved for red danger signs.
Red Safety Signs, Three Different Meanings
Red causes the most confusion, because it is used for three separate sign categories, distinguished by shape and layout rather than colour alone.
Prohibition, Red Circle with a Slash
A red circle with a diagonal slash over a black symbol, on a white background, means an action or behaviour is not permitted. Common examples are No Smoking, No Unauthorised Entry and No Mobile Phones in Operating Plant Areas.
Danger, Red Oval Inside a Black Rectangle
The word DANGER in white letters on a red oval, set inside a black rectangle, warns of a hazard likely to be life threatening. Danger signs never carry a pictogram under AS 1319, the wording carries the message on its own.
Fire, Solid Red Background
A solid red background with white symbol and/or text advises the location of fire alarms and fire fighting equipment. This is treated as its own category, separate from both prohibition and danger signs.
Telling the three apart at a glance: circle with a slash, something is forbidden. Oval inside a black rectangle with the word DANGER, a life threatening hazard. Solid red rectangle, fire equipment is nearby.
Green Safety Signs, Emergency Information (Safe Condition)
Green identifies emergency related facilities and safe conditions, using a white symbol and/or text on a green background. This covers first aid points, emergency exits, evacuation routes, emergency showers and assembly areas, the places a person needs to find quickly during an incident.
Common Safety Symbols and What They Mean
Colour tells you the category, the pictogram tells you the specific hazard or instruction. Some of the most common symbols used across Australian workplaces:
- A skull and crossbones indicates a biohazard or poisoning risk
- A flame indicates a flammable material or fire hazard
- An exclamation mark indicates general caution
- A crossed-out wheelbarrow or forklift indicates no entry for vehicles or plant
- A lightning bolt indicates an electric shock hazard
- A running figure toward a door indicates an emergency exit
- A cross indicates a first aid point
The Standard Behind the Colours
Every colour, shape and layout described above comes from AS 1319-1994, Safety Signs for the Occupational Environment. The standard was reaffirmed in 2018 and remains the current reference for Australian workplaces, mine sites and construction sites, there is no newer edition in place of it.
AS 1319 also specifies the symbols permitted for each sign type, so a business cannot substitute its own colour scheme or icon set and still claim compliance. For sites that also need to align with international pictograms, ISO 7010 is the relevant international reference, though most Australian workplaces only need to meet AS 1319.
Related → Guide to OHS Safety Signs
Frequently Asked Questions
What colour are mandatory signs?
Mandatory signs are blue, specifically a white symbol on a blue circular background. They specify an instruction that must be carried out.
What colour is a warning sign?
Warning signs are yellow, a black pictogram inside a yellow triangle with a black border. They warn of a hazard that is not likely to be life threatening.
What colour sign identifies a hazard?
Yellow identifies a hazard that is not likely to be life threatening (warning signs). Red identifies a hazard that is likely to be life threatening (danger signs), shown as a red oval with the word DANGER, no pictogram.
Are all red safety signs about danger?
No. Red covers three categories: prohibition (red circle with a slash, something is not permitted), danger (red oval inside a black rectangle, a life threatening hazard) and fire (solid red background, fire equipment location).
What does a blue safety sign indicate?
A mandatory instruction that must be carried out, most often a PPE requirement such as wearing a hard hat, safety glasses or hearing protection.
What does a green safety sign mean?
Emergency information or a safe condition, such as the location of first aid, an emergency exit, an evacuation route or an assembly point.
Why are warning signs yellow?
Yellow is one of the most visible colours to the human eye against most backgrounds, which is why it is used for warning signs, hazard tape and hi-vis clothing. It signals caution and attention, distinct from red, which is reserved for prohibited actions, life threatening danger, and fire equipment.
The Bottom Line
Blue means must do, yellow means be aware, green means emergency information, and red means one of three things depending on the shape, prohibited, life threatening danger, or fire equipment location. Reading colour and shape together, not colour alone, is what makes AS 1319 signage work as an instant, language-independent safety system.
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