What Substances Require a COSHH Assessment?

A COSHH (Control of Substances Hazardous to Health) assessment is an essential set of regulations that any workplace that exposes its workers to hazardous materials must have in place to ensure the health and safety of those workers. COSHH regulations help minimise the risk of exposure and harm that is caused by these substances, but exactly what substances require a COSHH assessment? In this blog, our health and safety experts at HSEDocs are going to outline the types of substances that require a COSHH assessment and why it's so important to have these regulations in place.

So, what substances require a COSHH assessment?

COSHH assessments cover any substances that would be considered hazardous to someone's health, no matter the form in which they come. This can therefore include substances such as chemicals, liquids, fumes, vapours, dust, gases, bacteria, viruses and even nano-particles. This means that a COSHH assessment is important across a variety of industries.

Read on to find out more about the different types of substances which require a COSHH assessment and why it is so important to complete this assessment in order to minimise risk within the workplace.

What Does COSHH Identify As a ‘Hazardous Substance’?

A substance which is considered hazardous is any type of substance that can have a harmful effect on a person's health. That's why it’s important to understand the types of substances that can be classed as ‘hazardous’ in order to place the proper precautions in place to minimise the risk within your workplace. We’ve highlighted in more detail below the different types of hazardous substances that would require a COSHH assessment to help you identify them:


This is one of the most common hazardous substances within the workplace whether it be in the physical-chemical products that are used or the chemicals that are produced in the workplace. This can include substances such as cleaning products, adhesives and paints.


This hazardous substance is often more industry-specific than chemicals and can be found typically in workplaces such as building sites. Examples of where fumes can be found are in welding, burning rubber and soldering.


Although vapours and fumes may seem the same they are two separate substances. One of the most common vapours found within workplaces is a solvent vapour which is released from substances such as paints or adhesives.


Dust is a really common hazardous substance and can be found in a number of workplaces produced from materials such as wood, metal, rubber and stone. Dust is considered hazardous as it may contain microscopic particles of either liquid or solid droplets which can cause potential health problems in areas such as the lungs.


Hazardous gases include gases such as carbon monoxide or chlorine which when exposed to for a certain amount of time can be extremely toxic. Other types of gases which would be considered hazardous include ones that are flammable, toxic or corrosive.

Germs (That Cause Diseases)

In this instance, COSHH covers any germs that cause diseases or germs that are used within laboratories. These germs may cause diseases such as legionnaires and leptospirosis.

Other types of substances that COSHH covers include products containing chemicals, mists, nanotechnology and biological agents. These are just some of the types of COSHH assessments that would be required across multiple different industries and job roles from cleaners using cleaning chemicals to builders using spray paint.

What Substances Are Not Covered By COSHH?

Not all hazardous substances are covered by COSHH as they have their own specific regulations which must be followed if found within the workplace, these include:

Why Is A COSHH Assessment Important?

By assessing what substances are hazardous and deciding how to prevent harm through a comprehensive COSHH assessment, an employer can put a series of rules and regulations that will help protect their employees from being exposed to hazardous substances. In many different work environments, people use hazardous substances every day so it's important to have these procedures in place to prevent unnecessary injury and harm. To find out more our experts discussed the importance of COSHH in our recent blog.

What Factors May Trigger a COSHH Assessment?

A COSHH assessment will be lawfully required by a business which carries out any processes which may potentially cause harm to the health of its employers or creates new substances in the working environment. The most common thing that may trigger a COSHH assessment to be reviewed however, is if an accident occurs within the workplace which involves a hazardous chemical. A review will determine whether this accident could have been prevented and what measures need to be put in place to stop it from happening again.

COSHH Resources At HSEDocs At HSEDocs

we offer a wide range of specifically designed COSHH documents, including COSHH Data Sheets and risk assessments for a number of industries from cleaners to painters.

To find out more, explore our range of COSHH documents online, or if you need any advice on any other safety work please get in touch with one of our friendly team members who are more than happy to help.

Related Questions

Is Bleach Covered By COSHH?

In short, yes, bleach is covered by COSHH as it is considered a hazardous substance. This is because bleach can be an irritant for both the eyes and skin, so it's important to follow all the correct precautions to protect yourself and your employers.

Is a COSHH Assessment the Same As a Risk Assessment?

No, despite the fact that they both aim to lower risk in the workplace, a COSHH assessment and risk assessment are not the same things. A COSHH assessment looks to identify hazardous substances whereas a risk assessment identifies potential injuries that can be caused by the hazards. To find out more about this topic why not check out our recent blog where we discussed all about it?