Hazard Signs and Their Meanings

Hazard signs are used across all types of workplaces. Construction sites, warehouses, waste facilities, and industrial environments all rely on them to highlight risks and keep teams safe.

If there's a hazard present, the right sign should alert everyone immediately.

However, seeing a hazard sign doesn’t always guarantee it’s understood. Bright colours attract attention, but symbols can be misinterpreted without clear guidance.

This guide explains hazard signs, their symbols, meanings, and how to use them effectively in the workplace.

What is a hazard sign?

Hazard signs are safety signs designed to warn of specific risks. They are typically yellow or red and feature black pictograms that represent the hazard.

These pictograms are standardised under BS EN ISO 7010, an international safety sign standard. This ensures hazard signs are recognised and understood across different workplaces and sectors.

The Types of Hazard Signs and What They Mean

WARNING SIGNS

Warning signs are yellow and black, triangular in shape, and usually include a pictogram with a short description.

They are used to highlight general hazards, including:

• Mind your head
• Danger of death
• Slippery surfaces
• Hot surfaces & hot water

CHEMICAL HAZARD SIGNS

Chemical hazard signs are red and white, diamond-shaped symbols. They are used on chemical containers covered by COSHH regulations and display GB CLP pictograms.

Common examples include:

• Corrosive - shows damage to skin or surfaces
• Harmful or irritant- indicates substances that may cause irritation
• Toxic - highlights substances that can cause serious harm or death

ELECTRICAL HAZARD SIGNS (HIGH VOLTAGE)

These signs warn of electrical hazards and high-voltage exposure. They typically feature a lightning bolt symbol and are used near live electrical equipment.

EXPLOSIVE SIGNS

Used to indicate substances or materials that could explode under certain conditions. The symbol on the sign shows an exploding bomb.

OXIDISING SIGNS

Warn of oxidising substances that can increase fire or explosion risks. The symbol on the sign shows a flame over a circle.

FLAMMABLE SIGNS

Flammable signs indicate substances that can easily catch fire. The symbol is a simple flame.

COMPRESSED GAS SIGNS

Used to warn of gas stored under pressure, which may explode or ignite. The sign has a symbol that shows a gas cylinder.

 

MARINE POLLUTANT SIGNS

Also known as environmental hazard signs. These indicate substances harmful to wildlife and natural environments. The symbol of the sign shows a dead fish and a tree.

How to Use Hazard Signs in the Workplace

Correct placement and understanding are just as important as the sign itself.

IDENTIFY HAZARDS WITH RISK ASSESSMENTS

Risk assessments help identify hazards and determine which signs are required. Once risks are identified, the correct hazard signs can be selected to support wider control measures.

Using a structured risk assessment process helps ensure nothing is missed.

PLACE HAZARD SIGNS IN CLEAR VIEW

Hazard signs should be positioned close to the hazard they relate to, usually at eye level. In some cases, they may be placed directly on or above machinery.

Signs must remain visible at all times. They should not be blocked by equipment and should be well lit.

Reflective or glow-in-the-dark signs can help in low-light areas

PROVIDE HAZARD SYMBOL TRAINING

Not everyone understands hazard symbols instinctively. Training is a legal requirement and helps teams recognise hazards quickly, even without additional explanation.

A clear understanding reduces risk and improves overall site safety.

MAINTAIN AND REPLACE SIGNS REGULARLY

Over time, signs can become damaged, dirty, or faded. Regular cleaning should form part of routine site maintenance.

If a sign becomes difficult to read or no longer meets required standards, it should be replaced immediately.

Make your workplace safer with hazard signs from SMI

SMI supplies a wide range of safety signs to support workplace compliance and risk management, including:

• Hazard signs
• Machinery signs
• Hazardous substances signs

Whatever warnings your workplace requires, our team can help you find the right solution.

FAQs

Where should hazard signs go?

Hazard signs should be positioned close to the hazard, at eye level where possible. They must be clearly visible, well lit, and unobstructed.

For darker areas or power outages, photoluminescent options such as XTA-GLO and Nite-Glo signs are available for low light areas and power outages. 

Are hazard signs required by law in the UK?

Yes. UK health and safety law requires employers to display appropriate hazard signs based on the risks present.

Signs must be maintained, replaced when needed, and used alongside other control measures such as PPE.

What safety signs are needed in the workplace?

Most workplaces require a combination of safety signs, including:

• Traffic signs
• First aid signs
• Fire safety signs
• Mandatory signs
• Prohibition signs
• Safe condition signs