Last updated: 18.04.24

What are the COSHH Principles?


Hazardous substances can be present in workplaces in a wide variety of industries, from manufacturing to food preparation and healthcare. They can be fairly minor hazards such as cleaning products that might cause skin irritation, to more serious risks such as chemicals that could be fatal if used inappropriately. As a result, both employees and employers must take the necessary precautions to control these substances.

COSHH is the official legislation that helps ensure the safe control of hazardous substances at work. In this article, we are going to discuss the basic principles including what it covers, what your responsibilities are, and some tips on how you can go about following these requirements.

Important: COSHH training is essential for anyone responsible for the control of hazardous substances. With this in mind, this article is intended as a guide only.

What is COSHH?

COSHH (pronounced as ‘cosh’) is the framework and law that explains how employers must adhere to the Control Of Substances Hazardous to Health. These regulations help ensure the safety of those working with harmful substances to help avoid potential risks. 

This comprehensive set of rules requires employers to limit and control exposure to hazardous substances. It also sets down how employers and employees should act in the event of an incident.

What are Hazardous Substances?

There are a huge number of potential substances that could be considered hazardous, and they extend beyond easily recognisable chemicals. Generally, substances hazardous to health include the following:

  • Products containing chemicals
  • Mists
  • Dust
  • Vapour
  • Fumes
  • Gases
  • Disease-causing germs
  • Biological agents
  • Nanotechnology

These could occur in a wide range of environments, so vigilance is required.

Some hazardous substances are not covered by COSHH because they have their own individual legal requirements and their own legislation. This includes asbestos, lead, and substances that are radioactive.

What are the COSHH Responsibilities?

The overall aim of COSHH is to reduce the risk of people coming into contact with hazardous substances. There are many different ways in which this can be carried out, which will be detailed in the next section. 

It is your legal responsibility to keep employees safe from harm while they are working by following the advice laid out in the Control of Substances Hazardous to Health Regulations 2002. Failure to adhere to these responsibilities can put employees at risk and also carries with it legal repercussions. Both individuals and corporations can be held to account by the Health and Safety Executive.

The Principles of COSHH

There are numerous ways in which you can ensure your employees are safe when working in the same area as hazardous substances, and there is a process to follow. Keep reading to learn more about how to adhere to these regulations and prevent risks.

COSHH Risk Assessment

Just as with all potential hazards in the workplace, a core component of COSHH is carrying out a risk assessment to determine exactly what hazards are present. This is usually known as a COSHH Assessment, and the HSE (Health and Safety Executive) has guidance available to help employers understand exactly how this can be done. 

In short, it involves assessing your place of work, and noting down all of the potentially hazardous substances contained within it, and where they might come into contact with employees.

Substance Substitution

One of the simplest solutions to dealing with risk is to replace a hazardous substance with one that is not dangerous. This could mean changing one cleaning fluid to a less harmful one or even swapping a powder for a liquid that can be stored, used and controlled more easily.

Minimising Emission and Spread

It is important to try to create processes that will help to minimise the emission, release and spread of harmful contaminants. Ensuring this is done before the hazardous substances occur will save money and time as prevention is often more proactive. 

Understanding processes and procedures that cause the emission, release and spread of harmful substances should be considered. Knowing how people are exposed whilst they are at work will ensure that these sources can be controlled and lessened. These should be reduced in number, size and release rate wherever possible. Without following these steps, you will struggle to gain control over these hazardous contaminants.

Effective Control Measures

Noting all possible routes of exposure will help when developing control measures against these hazards. These can occur through inhalation, skin contact or ingestion. 

When considering the different routes of exposure, it is also necessary to assess the level of impact they will have on a person's health. Managing control measures includes knowing the health effects that the contaminant can cause, the way the substances are used, how often they are exposed and where or how the exposure occurs. Be sure to also pinpoint all sources and possible routes of exposure and then rank these in order of importance.


Risk assessments will help determine the routes by which harmful substances might put someone at risk. This should then help you understand what control measures can be put into place to reduce the dangers.

Personal Protective Equipment

Personal Protective Equipment or PPE is vital when working with hazardous substances as things like masks, overalls and goggles can all help prevent contact with harmful contaminants. However, it is best to use this control measure alongside the others, as it tends to be less effective on its own. 

When using PPE, it is important to note that it has to be selected for each person, not interfere with their work, be fitted properly, be stored correctly and not get damaged. All of these factors can make personal protective equipment less effective than some of the other control measures.

Limiting Exposure

In areas where it is essential to work with hazardous substances, measures should be taken to reduce that exposure where possible. This can include many steps, which deserve full documentation in their own right. 

Reducing the chance of exposure will involve equipping employees with protective clothing, properly storing hazardous substances, and reducing the time spent carrying out potentially dangerous tasks.

Information Sheets

Some hazardous substances can be complex in their handling and storage needs. It is essential that employees can easily access data sheets. These documents should explain how they should use the substances they’re working with, which is especially significant if the substances are likely to come into contact with people unfamiliar with them.

COSHH Training

Following on from the previous point, training and constant education should be carried out wherever possible to make sure that employees, and indeed, employers, know what they should do to reduce the risk of exposure to hazardous substances. Always have a structured training regime in place to ensure knowledge and skills do not lapse.

Reviewing Controls and Dealing with Emergencies

As part of your COSHH procedure, you must also make provisions for when things do not go according to plan. Accidents can and do happen, and to mitigate the impact when they occur, you should be prepared. 

Specific incidents can be planned for, which may include everything from providing first aid to those affected to designating people who must call for emergency services.


Why is COSHH important? 

COSHH regulations help to minimise the risks associated with handling hazardous substances. They are important in ensuring the safety of those working with these contaminants and help reduce the potential risks that may occur. 

Why was COSHH introduced?

COSHH was introduced as a part of a movement towards improving workplace safety. It was put in place to help formulate safety measures that employers were already following under the Health and Safety at Work Act 1974. COSHH has been vital in ensuring safety at work and gives people an incentive to ensure the environments they operate in are as safe as possible.

Who has the legal responsibilities under the COSHH regulations?

Employers are responsible for providing employees with all the information and guidance they need for working safely with hazardous substances. Training and education should be provided to guarantee all members of staff can work safely and reduce their risks when exposed to harmful contaminants. The employer should also make sure that all necessary procedures are in place to minimise dangers or accidents happening at work. 


The principles of COSHH are extremely important. Adherence to these principles allows employers and employees to work safely whilst complying with legislation. Following the necessary steps above will ensure that all those handling hazardous substances can do so carefully and properly. 

If you’re looking for more information about the COSHH principles, Virtual College offer an online ‘COSHH Training Course’ which allows you to understand the protocols and necessary guidance in further detail, ensuring you’re adhering to current regulations.