Dangerous Substances in the Workplace

When left unchecked, enough of a substance can cause the ignition of an atmosphere, creating an explosion. All workplaces working with potentially dangerous substances must be aware of the hazards they pose.

A lot of different factors can be the direct result of an explosion. Explosive atmospheres can be caused flammable gasses (both visible and invisible), mists, vapours, combustible dust or hidden residue left somewhere. When these substances mix with air, a mere spark can be the difference between safety and an explosion occurring.

Every year workers are injured or killed as a result of negligence around potentially explosive materials. Only recently, a worker was nearly killed and badly burned after he was cutting up a fuel tank that had leftover fuel residue inside, causing an explosion.

As well as loss of life, explosions can cause significant damage to property and can cause fires, leading to further damage and further hazards to those within the area.

Learning about these dangerous substances and how they might come about is of the utmost importance for anyone who may be in the area or involved with the management of the health and safety of employees. The following is a brief guide to the various types of substance that may have explosion risks.


Many different types of liquid emit vapour which, when mixed with air, can explode if ignited. Examples of liquids that can be combustible include petrol and other fuel types, paint, ink, adhesives, cleaning fluids and other solvents.

Liquids should be tested using a physical test known as Flashpoint to determine the minimum temperature the liquid will give off enough vapour to ignite the atmosphere. By doing this, liquids can be categorised into three classes:

Extremely Flammable

These liquids have a flashpoint lower than 0°C and boiling point lower than or equal to 35°C.

Due to the nature of these liquids, extra precautions must be taken to ensure that excessive vapour leaks cannot occur. Protective equipment, such as explosion-proof testers and other intrinsically safe equipment must be used. Special protective equipment and breathing apparatus may also be necessary to protect employees from being overcome by the fumes (particularly inside confined spaces).

Highly Flammable

Not as dangerous as extremely flammable liquid, but still a significant danger. These liquids have a flashpoint below 21°C.


Liquids which have a flashpoint equal or greater than 21°C.


Dust that forms in the air is extremely dangerous. It can be toxic to breathe, hazardous to the health and is also a combustion risk that may explode when exposed to an ignition source.

Residual dust in the air can come from many different sources; everyday materials such as coal, wood, flour, grain, sugar, certain metals and chemicals can all produce dust. Dust can commonly be found in food production, chemical production, woodworking, rubber factories, plastic processing, mines and more, making the importance of safety around dust atmospheres of the highest importance for all employees.

A naked flame or spark in the air could cause a massive explosion if a large cloud of dust exists.


Gas exists in many forms. Both invisible and visible and toxic/non-toxic, uncontrolled gas is extremely hazardous. It can also be highly combustible, with certain gasses such as methane or petroleum gas being more than capable of reacting with a naked flame and causing an ignition.


Although not as high risk of causing combustion, solid materials such as plastic foam, packaging and textiles can be highly flammable and give off toxic fumes such as black smoke.

Chemical Substance Storage

Chemicals can often be highly volatile, reacting differently to changes in heat, pressure or other factors. Correctly storing a chemical safely ensures that incidents involving chemicals don’t occur and the correct process controls to operate safely with the chemical must be followed to prevent accidents.

These are just a few of the risks posed by substances in the workplace. By UK law it is the responsibility of any employee to ensure that employees are protected at all times from hazards at work; neglecting these is extremely dangerous and steps must be taken to implement safe working practices.

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