Quick answer
Read a safety sign by its shape, colour, pictogram and context. Red prohibition signs forbid an action; blue signs require an action; yellow signs warn; green signs identify escape or first-aid arrangements. Red is also used for fire-equipment signs, so colour alone is not enough.
A sign needs a clear message and a usable precaution
A worker needs to recognise what a sign means and what to do. Signs help communicate remaining risks and required actions, while the physical and organisational controls still need to work.
HSE’s signs and signals guidance explains the GB requirements and sign families. NI’s regulations set out corresponding scheduled colour and sign requirements. Use the relevant national rules alongside any premises-specific requirements.
1. Recognise the main sign families
| Family | Typical form | Meaning and example |
|---|---|---|
| Prohibition | Round; red border and diagonal bar over a dark pictogram on white. | An action is prohibited, such as no unauthorised access. |
| Warning | Yellow triangle with a dark border and pictogram. | A hazard needs attention, such as an electrical hazard. |
| Mandatory action | Blue circle with a white pictogram. | A specified action is required, such as wearing selected eye protection. |
| Emergency escape or first aid | Green square or rectangle with a white pictogram. | The location or route for escape, first aid or related facilities. |
| Fire equipment | Red square or rectangle with a white pictogram. | The location or identification of firefighting equipment. |
Use the pictogram and any supplementary information to understand the exact message. The red fire-equipment family is different from a red prohibition sign. A generic colour rule cannot explain every label or signal in a workplace.
2. Check whether people can see and understand the sign
Position signs where the information is needed, taking account of the approach, line of sight, obstructions, lighting and viewing distance. Keep them clean, secure and legible. Avoid clusters that make the important message hard to find.
Explain unfamiliar signs during induction or task instruction. Ask people to describe the action rather than simply name the colour. Consider communication needs and the conditions in which a sign must be recognised.
Hypothetical example: eye protection at an entry point
A blue eye-protection sign sits behind an open door. The manager reviews its position so the message can be seen before entry, checks that suitable equipment is available and confirms that workers understand when and how it is required. Moving the sign alone would not resolve missing or unsuitable protection.
3. Match signs to the current hazard and arrangements
A sign should remain accurate after a layout or work change. An escape sign needs to correspond to the assessed escape arrangement; a warning needs an appropriate response and control.
- Check new and changed work for the information people need.
- Check the relevant sign while approaching the hazard or decision point.
- Replace damaged, obscured or misleading signs.
- Remove a temporary sign when the condition it describes has ended.
- Make sure required equipment or action is actually available and understood.
HSE explains that signs supplement other controls. A warning does not repair defective equipment, create a usable exit or remove a slip hazard.
Common interpretation mistakes
- Red always means the same thing. Read the shape and pictogram.
- More signs always improve communication. Keep the necessary messages clear.
- Text alone solves unfamiliarity. Explain the action and check understanding.
- A permanent temporary warning. Address the condition and keep the information accurate.
Next steps
- Identify the sign family and exact message.
- Check visibility from the point where a decision is needed.
- Explain the action and provide the relevant controls.
- Maintain the sign and review it after changes.
Read HSE’s safety-sign guidance — Use the official forms and requirements when choosing or reviewing workplace signs.