Hazard Signs: What They Mean And How To Use Them

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Working with hazardous chemicals has always been a dangerous task. In the past, there was no standard system or labelling requirements to communicate the risks of working with hazardous materials.

As a result, employees often didn’t know what they were dealing with and used their best judgment when transporting, storing, or using hazardous chemicals. Such situations were not ideal and posed a significant risk to the safety of those working with the material.

Therefore, in an effort to keep employees safe, the United Nations (UN) developed the Globally Harmonized System of Classification and Labelling of Chemicals (GHS).

What is the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)?

GHS is an internationally-recognised standard used for communicating the hazards of chemicals in a uniform way that is understood by everyone around the world. GHS serves as a universal language, ensuring that everyone is on the same page when dealing with hazardous materials.

GHS has a set of defined hazard signs (also sometimes called warning signs or safety signs) that are used to alert workers of potential dangers.

In this article, we will take a closer look at the different GHS hazard signs and explain their meaning and how to use them.

But, before we go into GHS hazard signs, let’s first define what hazard signs are.

What Are Hazard Symbols?

Hazard symbols are pictograms used to quickly and clearly communicate the hazards associated with a chemical or substance. Each hazard symbol is assigned a specific meaning and purpose, allowing workers to recognise and act on hazardous materials they encounter quickly.

Hazard symbols are diamond shaped and contain different symbols and colours. The are two sets of pictograms included within the GHS.

Physical Hazards – For container labelling and workplace hazard warnings
Transportation Hazards – For the transportation of hazardous materials

GHS physical hazard signs are divided into three categories.

Health Hazards
Fire and Explosion Hazards
Chemical and Environmental Hazards

Each category is further divided into sub-categories depending on the type of hazard posed.

GHS transportation hazards are divided into different classes depending on the type of material being transported. These include.

Explosives
Gases
Flammable Liquid and Solids
Others

These classes are further divided into sub-classes called Divisions. Divisions specify the exact hazard posed by the material being transported.

Now that we have a basic understanding of what GHS hazard signs are, let’s take a look at each one in detail.

Hazard signs are just one element of the comprehensive GHS system. Please refer to our GHS label requirements guide for more information about GHS labelling and its requirements.

Physical GHS Hazard Pictograms

GHS Hazard Symbols in Case of Health Hazard

Name	Meaning	Intake	Hazard Indication	Example
Corrosion	Corrosive substances	Direct contact	Severe burns, Eye damage, Instant corrosion to metals	Strong acids or bases like sulphuric acid, nitric acid and sodium hydroxide
Skull and Crossbones	Poisonous substances that cause harm if they enter the human body Acute toxicity	Direct contact, oral and inhalation	Severe eye damage, Toxic if swallowed, contacted with skin or inhaled, Danger to life if swallowed, contacted with skin or inhaled	Carbon monoxide, manganese heptoxide, chlorine and hydrogen sulphide
Exclamation Mark	Cause harm to human health	Direct contact, oral and inhalation	Skin irritation, Eye irritation/damage, Allergic skin reactions, Respiratory tract irritation, May cause numbness, dizziness and drowsiness (narcotic effect), Organ toxicity, Harmful to the ozone layer	Products containing chemicals or biohazards like bodily fluids, blood or poisonous gases.
Health Hazard	Cause severe harm that results in long-term health issues	Direct contact, oral and inhalation	Breathing difficulties and diseases like asthma, Cancer, Mutagenicity, Genetic defects, Impair fertility, Harm to the unborn child, Organ damage/failure	Toxic and radioactive chemicals like mercury, chromium, lead, arsenic and uranium.

GHS Hazard Symbols in Case of Fire and Explosion

Name	Meaning	Example
Exploding Bomb	Explosives, self-reactive substances and organic peroxide that may mass explode in a fire	Azidoazide azide, TNT, Di- and Tri-nitro compounds, chromyl chloride, nitroglycerine
Flame	Flammable gases, aerosols, liquids and solids that: May catch fire when in contact with air. Have a low flash point. Produce flammable gas when it comes in direct contact with water. Catch fire with very short contact with an ignition source.	Most solvents like acetone and methanol
Flame Over Circle	Oxidising solids, liquids or gases that cause or intensify fire or explosion.	Most halogens like fluorine, chlorine, bromine, and iodine

GHS Hazard symbols in Case of Chemical and Environmental Hazard

Name	Meaning	Example	GHS Pictogram
Gas Cylinder		Gases stored under pressures that may explode if heated	Liquid nitrogen, liquid helium, liquid oxygen, butane, propane
Environment (Dead Tree and Fish)		Substances that are toxic to aquatic life and aquatic environments.	Cadmium, zinc, aluminium

Transportation GHS Hazard Pictograms

Class 1 - Explosives

Division	GHS Pictogram	Usage
1.1		Substances and articles with mass explosion hazard
1.2		Substances and objects that pose a projected hazard but will not cause a mass explosion
1.3		Substances and items that can cause a fire with a minor blast hazard, a minor projected hazard, or both but will not cause a mass explosion
1.4		Products classified as explosives but do not pose any significant hazards
1.5		Insensitive substances with a mass explosion risk
1.6		No hazard statement

Class 2 - Gases

Division	GHS Pictogram	Usage
2.1		Flammable gases which are at 20°C and have a standard pressure of 101.3 kPa and : Ignite when mixed with 13% (or less) by volume with air; or, Have a flammable range of at least 12% with air, irrespective of the lower flammable limit.
2.1 – Alternative Sign
2.2		Non-flammable, non-toxic gases that are. Asphyxiant (gases that dilute or replace the oxygen present in the atmosphere); or, Oxidising (gases that provide oxygen, contributing to more combustion); or, not included in the other categories
2.2 – Alternative Sign
2.3		Toxic gases that are. Known to be poisonous or corrosive, causing human health hazards; or, Presumed to be poisonous or corrosive because they have an LC50 value equal to or less than 5000 ml/m3 (ppm).

Class 3 and 4 - Flammable Liquids and Solids

Division	GHS Pictogram	Usage
Class 3		Flammable liquids with a flash point of less than 60 °C and are capable of supporting combustion
Class 3 – Alternative Sign
4.1		Flammable solids, self-reactive substances and solid desensitized explosives that. Are readily combustible, Cause or contribute to fire because of friction, May undergo a strongly exothermic reaction, May explode if not diluted sufficiently.
4.2		Substances and articles prone to spontaneous combustions under normal transportation conditions and contact with air
4.3		Substances and articles that emit flammable gases when exposed to water
4.3 – Alternative Sign

Other Transport Classes

Division	GHS Pictogram	Usage
5.1		Oxidising substances and articles that are not necessarily combustible themselves but may cause or contribute to the combustion of other materials by emitting oxygen.
5.2		Organic peroxides that contain the bivalent –O–O– structure and are considered derivatives of hydrogen peroxide, where one or both hydrogen atom is replaced with organic radicals
5.2 – Alternative Sign
6.1		Toxic products with. An LD50 value ≤ 300 mg/kg (oral); or, An LD50 value ≤ 1000 mg/kg (dermal); or, An LC50 value ≤ 4000 ml/m3
6.2		Infectious substances and articles very harmful to human health
Class 7		Radioactive materials
Class 8		Corrosive items that. Cause complete thickness destruction of intact tissue after less than four hours of exposure; or, Show corrosion on either steel or aluminium surfaces at a rate greater than 6.25 mm per year at a temperature of 55 °C.
Class 9		Other dangerous substances and articles that pose risks to humans

Conclusion

Hazard signs are essential tools that help identify potential dangers. They are necessary to ensure the safety of workers who may come into contact with hazardous materials.

In this blog post, we’ve taken a look at what hazard signs mean and how to use them. Remember, if you see a hazard sign, take the appropriate action and follow all safety protocols for a safe working environment.

There’s no better way to print hazard signs and GHS labels than using a thermal printer. Thermal printers provide high-quality prints, ensuring maximum visibility for your hazard signs.

At Triton, we offer a variety of thermal printers from brands such as Honeywell, Zebra, and TSC that can help you print GHS hazard symbols quickly and accurately. With our durable, long-lasting printing consumables, you’ll get the best possible results for your hazard labels. We also offer BarTender software to help make labels that may contain hazard signs.

We also have a team of experts who are always ready to help you choose the right labelling solution for your needs. Contact us today via the live chat widget below, and let us help you find the perfect thermal printer and labels for GHS labelling.

We hope this article has been informative and helpful in providing you with an understanding of GHS symbols.

Thanks for reading!