Quote Request

Contact Us

My Basket (0)
What Everybody Needs to Know About COSHH Assessments

What Everybody Needs to Know About COSHH Assessments

Reading time: 23 minutes.

What you need to know

COSHH stands for the Control of Substances Hazardous to Health regulations.

It was introduced over 30 years ago to regulate the use of hazardous substances at work. Employers and self-employed people must assess the risk (complete a COSHH assessment). Through effective control and monitoring procedures, employees must be protected from harm.

While general health and safety risk assessments are common, a COSHH assessment focuses on the specific risks of hazardous substances in the workplace.

You might be surprised to learn that there are around 500 hazardous substances with workplace exposure limits (WELs) listed in EH40/2005, but COSHH also applies to a much wider range of substances.

To meet the requirements of the regulations you must understand the possible ways in which your employees could be exposed and the types of controls you will need to put in place such as ventilation systems, for example. You must also consider possible serious long-term effects such as cancer, as well as more minor short-term risks like skin irritation.

By completing a thorough COSHH risk assessment, you will identify any hazardous substances you are using, including those created when substances are mixed together or produced by your work. You will then be able to consider:

  • what effects these substances could have
  • who is likely to be exposed and how
  • what you are currently doing to control the risks
  • other control measures needed to protect people from harm.

You might be able to use a different, non-harmful substance or use new procedures and equipment to minimise risks to your employees and anyone else on the premises. The greater the level or risk, the more controls you are likely to need. You will also need to consider accidents or emergencies and how you would keep people safe from exposure.

What happens if you don’t properly complete a COSHH assessment?

There are likely to be some hazardous substances in every workplace, from cleaning products and solvents to exhaust fumes or dust. If you don’t take the right steps to find out about these hazardous substances and how people could be harmed there are serious penalties.

You could receive cautions, prohibition or improvement notices, fines. Your approval to operate could even be withdrawn by the Health and Safety Executive or your local authority.

For serious breaches of the regulations you could find yourself in court facing unlimited fines and a prison sentence. If someone is hurt or tragically dies you might also be required to pay compensation. You could be found guilty of corporate manslaughter.

What you will learn from this guide

This guide explains why a COSHH assessment is needed. You will have a clearer understanding of the range of substances that can be hazardous to health and where you will find useful information.

The basic principles of carrying out a COSHH assessment are described in a straightforward step-by-step guide.

You will see why training and maintaining good records are essential and understand why proper storage and signage are needed.


What is a COSHH risk assessment?

You must control the risks to employees if your business uses or creates hazardous substances or carries out processes that produce substances which might be harmful to health.

The first step in your COSHH risk assessment is to check the substances you use or create in the workplace to find out whether they could be harmful. Product labels and safety data sheets (SDS) are good sources for this information. If you aren’t sure or you can’t find the information, contact your supplier.

As well as substances that are labelled as ‘hazardous' your assessment must also include hazardous dusts, vapours or fumes, for example. You must also understand whether any combinations of substances can become hazardous or can create hazardous by-products.

Your employees and others can be exposed to these substances by breathing them in, by touching them or swallowing them.

The potential for harm will depend on how often people work with the substance and for how long.

You will need to think about whether anyone else, such as contractors, visitors or members of the public could be exposed. You must also consider what would happen if there was an accident due to faulty machinery or a spill, for example.

Evaluating the risks of exposure to hazardous substances

Your COSHH assessment must include an analysis of the ways in which exposure can be prevented. This can include assessing whether you could use alternative substances and whether you can change your processes to remove or reduce the risk of exposure.

If it isn’t possible to remove the risk all together, you will need to look at control measures to reduce the level of risk to an acceptable level. Enclosing the substance, ventilation, handling and storage methods could all be used.

You should also look at ways to reduce the number of people who might be exposed, make sure that areas affected are regularly cleaned and have effective and safe ways to remove spills and build-ups.

It’s good practice to keep a written record of your COSHH risk assessment and the actions you have taken to control the risks to health. If you have five or more employees, you are required to keep a written record.

Your risk assessment must be regularly reviewed so that it stays up to date and should always be reviewed if processes, substances or locations are changed.

You can use our COSHH risk assessment template as a starting point.

Download Free COSHH Assessment Template
Back to index

Overview of common substances hazardous to health

Thousands of substances are used at work but only about 500 substances have Workplace Exposure Limits (WELs).

However, there are many other substances that are hazardous to health which are covered by COSHH including:

  • chemicals
  • products containing chemicals
  • fumes
  • dusts
  • vapours
  • mists
  • nanotechnology
  • gases and asphyxiating gases and
  • biological agents (germs).
COSHH danger symbol
COSHH warning symbol
COSHH Long-term health hazard symbol
Long-term health hazard
COSHH danger to environment symbol
Danger to environment
COSHH corrosive symbol
COSHH flammable symbol
COSHH oxidiser symbol
COSHH explosive symbol
COSHH compressed gas symbol
Compressed gas

Here are some of the most common hazards:


Safety data sheets provide information on chemical products that help users to make a risk assessment. They describe the hazards and give information on handling, storage and emergency measures in case of an accident. Hazardous chemicals include:

  • Paints - paints and coatings contain several substances that can lead to health problems, including skin, eye and mucous membrane irritation, headaches, dizziness, sickness and lung disease. In the most serious cases they can affect the nervous system, blood, liver and kidneys and even cause cancer. Solvents used in coatings also give off vapours that can cause headaches, drowsiness and even unconsciousness. You can become seriously ill very quickly; in some situations, people could die.
  • Paint thinners – the solvents used in paint thinners are also known as VOCs (volatile organic compounds). Potentially harmful solvents include toluene, xylene, white spirit, acetone and ethyl acetate. When used in spraying processes very high exposures are possible.
  • Printer toner – toner used by photocopiers and laser printers is a very fine powder. People can be exposed when cartridges are replaced. For people with medical conditions such asthma or bronchitis this could be an irritant.
  • WD40 – While the lubricant WD40 is known to be flammable, it is also subject to a WEL. The effects of exposure include dizziness, drowsiness, and nausea.
  • Petrol, diesel and liquefied petroleum gas (LPG) - Petrol and diesel contain substances that may cause cancer. Their vapours should not be inhaled. Skin should be protected from their liquid forms (LPG) and they are also known to be dangerous to health if inhaled at high concentrations. The correct choice and use of equipment, ventilation and personal protective equipment (PPE) is important.

Products containing chemicals

  • Cleaning products - the most common substances containing chemicals subject to a COSHH assessment are cleaning products. Some ingredients can cause skin allergies and asthma. Some are corrosive and can burn skin and damage eyes.
  • Cement – Cement-based products, like concrete or mortar, can cause serious skin problems such as dermatitis and burns. Employees who are handling and mixing cement powder or using wet mortar and cement are particularly at risk. Existing skin or allergy problems can become much worse Cement powder is also a respiratory irritant. The dust produced while cutting or drilling dried concrete and mortar can cause more serious lung disease.


  • Welding fumes – there is new evidence that exposure to mild steel welding fumes can cause cancer. Suitable controls should be in place for all welding work. Guidance for mild steel welding is due to be updated.


  • Silica - silica is naturally found in most rocks, sand and clay. Fine silica dust, which can get in to your lungs, is created in construction activities such as cutting, polishing, grinding and drilling. Long-term exposure to respirable crystalline silica (RCS) can cause lung cancer and other serious respiratory diseases.
  • Wood - Cutting and sanding wood using power tools can produce a lot of dust leading to serious health problems, including asthma. Dust from hardwood is known to cause cancer, including cancer of the nose. Both hardwood and softwood dusts have a WELs. Protection, extraction and health surveillance are likely to be needed.
  • Plaster - Gypsum or plaster of Paris is the most common type of plaster. Mixing dry plaster, sanding plastered surfaces and cutting plasterboard all lead to exposure to plaster dust, which is subject to a WEL. In addition, the compounds used to seal the joints between plasterboard can contain hazardous materials, including RCS. Sanding joints can therefore also be a hazard to health.


  • Inks, lacquers, adhesives, and cleaning solvents contain substances that can be released as vapours. These products can get onto your skin, causing irritation and dermatitis. They can also be absorbed through your skin and cause damage and illness, including asthma. Some vapours can lead to dizziness and drowsiness and they can affect the central nervous system. Long-term exposure can damage internal organs such as your liver and kidneys.


  • Fluids, especially those used in metalworking, can create mists that lead to lung diseases and asthma. Control measures including operational controls to minimise use and exposure, ventilation, respiratory protective equipment (RPE) and health surveillance are likely to be needed.


Nanomaterials include anything which is 100 billionths of a metre or less. They include devices or systems made by manipulating individual atoms or molecules, as well as materials that contain very small structures. Some of these materials have chemical and physical properties which can lead to a risk to health, so their use is subject to COSHH.

Gases and asphyxiating gases

  • As well as the risks of fire or explosion, improperly installed and maintained appliances and equipment can lead to gas leaks and carbon monoxide (CO) poisoning. Risks can apply to factories, mines, quarries, agricultural premises, construction sites and sewage works, for example. Control measures should include appropriate ventilation, monitoring, emergency procedures and training.

Biological agents

Biological agents (germs) require a COSHH assessment if any hazard symbols or warnings appear on the packaging. This includes germs used in laboratories.

  • Human waste - equipment contaminated with bodily materials, anatomical waste and orange or yellow-bagged clinical waste represent a risk to health and must be properly handled and disposed of.

The HSC’s Advisory Committee on Dangerous Pathogens provides advice on the hazards and risks of exposure to pathogens.

Common substances hazardous to health
Back to index

Are COSHH assessments a legal requirement?

As an employer you are required to prevent, reduce and control exposure to hazardous substances to protect your employees from harm and ill health.

COSHH provides a basic system for managing risks to health, outlining how you can prevent or reduce your employees’ exposure to hazardous substances. This includes:

  • identifying the health hazards (risk assessment)
  • preventing harm to health (removing hazardous substances)
  • reducing harm to health (control measures)
  • monitoring control measures
  • regularly reviewing control measures
  • providing information, instruction and training
  • monitoring exposure
  • health surveillance in appropriate cases
  • planning for emergencies.

However, to comply with the regulations you must make sure that you properly manage the specific risks you have identified in your workplace.

Back to index

Who should carry out a COSHH assessment?

As an employer you must not undertake work that can expose employees to any hazardous substance until ‘a suitable and sufficient assessment of the risks to employees’ health… has been carried out’.

To do this, you must make sure that competent people complete the assessment. You are responsible for checking that they are competent.

COSHH regulation 12 requires you to make sure your employees are qualified and have enough knowledge and expertise to allow you ‘to make valid decisions about the measures needed to prevent or adequately control the exposure of employees to substances hazardous to health arising from their work’.

To be competent, a person should:

  • know how substances hazardous to health are used, produced or created in your workplace
  • understand the legislation, regulations and requirements
  • have the knowledge, skills, training and experience to make reliable decisions about the level of risk and the control measures needed
  • have the ability and authority of the employer to collate all the necessary and relevant information and make recommendations to control risks.

The Institution of Occupational Health and Safety (IOSH) guidance document Setting Standards in Health and Safety provides further useful information on setting competency levels.

A competently completed COSHH risk assessment:

What a competently completed COSHH assessment looks like, when done effectively What a COSHH assessment looks like when done badly, or not at all
  • Everyone knows the risks created by the business and understands how to manage them.
  • Key responsible people and job holders are identified and have clearly established roles and responsibilities.
  • People have the necessary training, skills, knowledge and experience to meet their responsibilities and have enough time to do so.
  • Training takes place during normal working hours and employees are not charged.

Beyond compliance
Lessons are learned and good practices are shared.

  • Lack of awareness of key hazards and risks.
  • People lack the skills, knowledge and experience to do their job.
  • Health and safety advice and training is irrelevant, incompetent or wrong.
  • No standards are set, and people are not held accountable.
  • Insufficient action is taken to comply with the law.
  • Incidents and near misses are not properly reviewed.
  • The organisation does not know what it needs to do to move forward.

According to guidance in the Approved Code of Practice (ACOP), a ‘suitable and sufficient’ assessment should take into account:

  • the properties of hazardous substances
  • how and when they can give rise to risks to health
  • the degree to which those risks need to be addressed.

Competent people will need to assess:

  • all of the substances used or produced in the work activity
  • whether they represent a physical, chemical or biological hazards, for example
  • the form they take, such as in a mist, gas or vapour
  • how people might be exposed
  • people who are especially at risk, due to a pre-existing condition, for example
  • the extent of exposure and potential health effects
  • control measures that may be required to eliminate or control exposure.

It’s also important to look at how the materials could be present at your premises. This could include substances that have been brought to the workplace by a contractor, by-products of a work activity such as waste products or dust, and substances used for maintenance or repair work.

It’s a good idea to complete a training needs analysis to highlight and address any gaps in knowledge or training. This could include work-based training and assessment from another competent COSHH risk assessor, for example. Competency should be reviewed whenever there are significant changes to working methods, equipment or substances.

Back to index

How to carry out a COSHH audit

Carrying out a COSHH audit gives you useful information that you can use to positively manage any hazardous substances you use. It is an ongoing process to make sure that hazards to health are being effectively managed in the workplace.

There are some simple principles to follow.

Planning - if you employ five people or more you must have a written plan and it’s a good idea to check it with your staff. Any control measures you put in place will only work with their support.

Practice - the methods you use to implement your plan must be effective and you need enough resources to implement them properly. Your plan needs to be practical and proportionate. If you work with advisors, they must be able to understand the whole of your business and give appropriate recommendations.

Checking – you must make sure that your plan is being properly implemented and that it is effectively controlling any hazards. If you find any shortcomings, further training and information might be needed for your employees.

Amendments - if your review shows that your controls need to be improved, if a serious incident occurs or if your processes or the substances you use change, you will need to update your plan. You should also have a scheduled review date for your whole plan to be confident that it remains fit for purpose.

How to carry out a COSHH audit
Back to index

How to carry out a COSHH assessment – a step-by-step guide

Many risks will be specific to your business and industry sector, so a single approach won’t be suitable for all situations.

You are responsible for identifying when and where there is potential for exposure to substances that might be hazardous to health.

This can include:

  • processes
  • by-products of your activities
  • mixtures of substances
  • handling and disposal
  • accidents
  • emergencies.

A thorough COSHH risk assessment will ensure that you have taken all the necessary steps to understand and control the risks.

You can make a start using our COSHH Risk Assessment template.

Download Free COSHH risk assessment Template

1. Information

To begin your COSHH risk assessment you will need to identify what substances you use and how they could be harmful to health.

Collecting safety data sheets (SDSs), is an important starting point. You should also keep up to date with news and best practices in your industry. The Health and Safety Executive provides information for specific industries.

Safety Data Sheets

These provide information on the substances you are using to help you make a risk assessment. They describe the hazards and give directions on handling, storage and emergency measures. Suppliers of chemicals must provide an up to date SDS if a substance is classified as ‘dangerous for supply’. Other substances should have instructions for safe use.


The HSE’s former Advisory Committee on Toxic Substances (ACTS) scheme provides a useful and practical method to choose suitable generic control approaches. Substances are allocated to particular hazard groups, based on their classification and labelling under the Classification, Labelling and Packaging of substances and mixtures (CLP) regulations, and the likely risk of exposure. Their generic risk assessment takes account of the health hazard classification and the exposure potential.


Substance allocated to a Hazard Group using H-statement.


Substance allocated to a dustiness or volatility band and a band for the scale of use.


Combine health hazard with exposure potential factors to determine the degree of control needed.


Approach needed for adequate control.

  • Hazard (H) statements - the health hazard assigned to substances during classification by suppliers under CLP.
  • Exposure potential - physical properties of the substances such as dusts from solids or vapour from liquids and the amount used.
  • Generic risk assessment - categorising substances into hazard groups and anticipated exposure ranges associated with the proposed use, for a range of different situations, to identify suitable control approaches.

Global classifications

Sometimes known as Risk phrases or R-phrases, these are internationally recognised systems of classification and labelling to identify the hazardous properties of chemicals and how information about these hazards should be passed on to users.

2. Your work and working practices

The processes that you use might not be covered by the safety data sheets, so you will also need to look at specific activities and any controls you already have in place. It might be helpful to divide processes up into smaller activities to help understand who could be exposed and the risks involved.

You will need to identify areas of concern that might be highlighted by the Accident Book, for example. These could include burns from splashes, nausea or light-headedness from solvent vapours.

3. Evaluation

Your assessment must look at how exposure could take place. You must consider what the consequences would be if the substances were inhaled, swallowed, absorbed through the skin or accidentally ingested.

To evaluate the risks, here are some helpful questions to ask:

  • what is the potential of one substance of a combination of substances to cause harm?
  • how likely is it that one or more people could be exposed?
  • how often could exposure occur?
  • what levels of exposure are possible and for how long?

In some cases, the possibility of exposure might be daily, but the risk is low because measures are already in place to prevent it. In other circumstances, the risk could be very high if control measures fail of it there’s an accident.

You should record the risks you have identified and possible accidents and emergency scenarios.

4. Control measures

Processes will be needed to make sure that your control measures are properly used, that those responsible know what they must do and that they are properly trained.

When you are confident that the risks have been properly identified you must look at how to handle them and the measures needed to meet the COSHH regulations (Sections 7 to 13).

To help you prioritise your plans, you can consider the following:

  • what are the most serious risks to health?
  • how soon are the risks likely to occur?
  • which risks can be controlled quickly?

Your control measures will probably be based on a combination of these answers, but any identified risk should have an associated plan to reduce or remove it.

Monitoring exposure should be considered as part of your assessment, especially where WELs or other levels are specified. In some cases, ongoing health surveillance will also be required, based on the recommendations of a qualified and competent occupational health advisor.

5. Reasonable practicability

There is a test of ‘reasonable practicability’ in COSHH. Your control measures should do everything that is practical and possible to reduce risks to the lowest acceptable level, according to good practice guidance.

The greater the risk the more reasonable it will be to do something about it. The use of personal protective equipment (PPE) is only acceptable if prevention or adequate control of exposure risks can’t be achieved reasonably and practicably by other more effective means. If you decide to rely on PPE, your assessment should make it clear why other means were not considered feasible.

6. Recording the assessment

If you have five or more employees, you must record the significant findings of your assessment. If you have fewer than five employees, you aren’t legally required to have a written record, but HSE strongly advises that you do, as good practice.

Even if all aspects of your assessment are not yet complete, you should include a note to identify when this information will be added.

Your assessment should explain your decisions and might refer to codes and good practice, industry standards and recommendations from manufacturers and suppliers.

7. Reviewing the assessment

The COSHH regulations don’t specify how often your assessment should be reviewed. However, it should be regularly reviewed for to confirm that it still covers all relevant risks and that the control measures continue to be appropriate.

Your records should include details of why decisions about risks and precautions were made. They must be meaningful and useful to the people who will need to implement control measures. Your assessment should always be reviewed if there is evidence that the original assessment is no longer valid and if circumstances change that could affect your employee's exposure to hazardous substances.

Online COSHH assessment tool

COSHH Essentials is an online COSHH assessment tool provided by the HSE that provides advice on controlling the use of chemicals for a range of common tasks such as mixing or drying for example.

You will work through a number of steps where you will be asked for information about your tasks and chemicals*.

It produces generic advice, so it is important that you check the advice sheets that you can download to make sure that they adequately describe the tasks and processes you follow.

*Note: COSHH Essentials only uses R-phrases/H-statements that relate to human health, so R1 – 19 / H200 – 290 (physical hazards) and R50 – 59 / H400 – 413 (environmental hazards) are excluded.

The structure of a COSHH risk assessment
Back to index

Storage of hazardous substances

If it is not possible to replace a substance that is hazardous to health, then the right equipment for chemical storage and handling must be used.

Firstly, you should limit access to the substances to those people who need to use them and who are properly trained in their handling and use.

Specific storage areas should be identified and either natural or powered ventilation and lighting should be provided. Pallets, kerbs and sumps should be provided as needed.

Surfaces should not be absorbent and should be easy to clean.

Take advice from your supplier about which substances should be stored separately.

Suitably strong cabinets should be provided for small amounts of materials with removable trays to make it easy to deal with any leaks or spills.

Storage of hazardous substances

All your storage arrangements should be checked regularly and have a planned and recorded testing and maintenance programme.

It’s also important to have appropriate equipment and cleaning materials available to deal with accidents and spills.

Back to index

COSHH signage

Your employees, contractors and visitors all need to be aware of any hazardous substances on site. The Health & Safety (Safety Signs & Signals) Regulations require signs to be displayed, so storage areas should be clearly marked with hazardous substance signs.

Chemical handling posters also help to remind everyone of the correct procedures to follow to prevent exposure to hazardous chemicals, and how to react if there’s an accident.

COSHH signage
Back to index

Summary of the key points in this guide

The Control of Substances Hazardous to Health (COSHH) regulations require employers to carry out a ‘suitable and sufficient’ assessment of the risks of using hazardous substances in the workplace.

As an employer of five or more people, you must keep a written record of your COSHH assessment and the control and monitoring measures you will use to eliminate the risk of harm or minimise it to an acceptable level. Even if you employ fewer than five people, a written record is good practice.

Some substances are subject to Workplace Exposure Limits (WELs) and their use must be carefully monitored. However, there are many other substances that are potentially harmful to health that must be properly controlled and monitored. Where substances are known to cause specific conditions and diseases, health surveillance of your employees will probably be needed, on the advice of a qualified occupation health professional.

Your COSHH risk assessment should also include possible accident and emergency scenarios and how you will protect people from harm.

COSHH assessments should be regularly reviewed to confirm that they remain fit for purpose. They should always be reviewed when practices, equipment or premises change and following any significant incident.

COSHH risk assessments - frequently asked questions

Can I use COSHH Essentials for my COSHH assessment?

As an employer you are legally required to complete a risk assessment that is ‘suitable and sufficient’ for your workplace. COSHH Essentials produces general advice. You must check that the Essentials sheets you download fully and accurately describe what you do. If they do, you can follow the advice they give. If not, you must consider what else you will need to do to avoid anyone’s health being harmed.

How often should I review a COSHH assessment?

Your COSHH assessment should be reviewed regularly to make sure it is up-to-date. How often you review your assessment will depend on the type of risk involved.

Your assessment should be reviewed immediately if there is any reason to think that it is no longer valid or if new information is available. It should also be reviewed when you change premises, ways of working, introduce new equipment or if there is an incident.

How do I use safety data sheets?

If a substance is ‘dangerous for supply’ your supplier must send you a safety data sheet when you first order the product, if the formulation changes, or if you ask for one. If it is not dangerous for supply the supplier should include instructions for safe use. The information on the sheet will help you to complete your risk assessment by describing what hazards are associated with the substance and giving information on handling, storage and emergency measures.

How should I record my COSHH assessment?

Your risk assessment will depend on the type of activities and substances you use in the workplace. It should be recorded in a way that reflects what you do, but it should include:

  • the dangers, what tasks are involved and anyone who might affected
  • control measures that can eliminate or minimise harm
  • how you will confirm that the control measures work.

What training should I have to carry out COSHH assessments?

You must be competent to carry the assessment so you must have the knowledge, skills and experience to:

  • understand the hazards and risks
  • know how people could be exposed to substances hazardous to health in your work environment
  • collect all the necessary information
  • make the right decisions about how to control exposure.