How to carry out a COSHH risk assessment

A COSHH assessment concentrates on the hazards and risks from hazardous substances in your workplace.

Remember that health hazards are not limited to substances labelled as 'hazardous'. Some harmful substances can be produced by the process you use, for example:

  • wood dust from sanding
  • silica dust from tile cutting
  • fumes from welding

Identify the hazards

Identify which substances are harmful by reading the product labels and safety data sheets (SDS). If in doubt, contact your supplier.

Think about harmful substances produced by your processes, such as cutting or grinding, or to which workers may be otherwise exposed. Examples include:

  • processes that emit dust, fume, vapour, mist or gas
  • skin contact with liquids, pastes and dusts

Substances with workplace exposure limits (WELs) are hazardous to health.

Assess the risks

Decide who might be harmed and how.

Think about:

  • how workers might be exposed (whether the substance can be breathed in, get onto or through the skin or can even be swallowed) and the effects of exposure by each of these routes
  • how often people work with the substance and for how long
  • anyone else who could be exposed - do not forget maintenance workers, contractors and other visitors or members of the public who could be exposed
  • what you're already doing to control the risks
  • what further action you need to take to control the risks
  • who needs to carry out the action
  • when the action is needed by

Control the risks

Once you have carried out a risk assessment and identified which harmful substances are present, and how workers can be harmed, you need to think about preventing exposure.


Do you really need to use a particular substance, or is a safer alternative available?

Can you change the process to eliminate its use or avoid producing it? If this is not possible, you must put in place adequate control measures to reduce exposure.

Changing the process to reduce risks

Consider whether you can change the process you use to reduce the risk of exposure. For example, you could reduce the temperature of a process to reduce the amount of vapour getting into the air or use pellets instead of powders as they are less dusty.


Enclose the process or activity as much as possible to minimise the escape or release of the harmful substance.

Use closed transfer and handling systems and minimise handling of materials.

Use a properly designed local exhaust ventilation (LEV) system which extracts dust, fume, mist, gases or vapour through a hood or booth and reduces the exposure of the worker.

All ventilation equipment must be examined and tested every 14 months by a competent person (someone who has the necessary skills, knowledge and experience to carry out the work safely).

Guidance on buying and using LEV

Systems of work

Restrict access to those people who need to be there.

Plan the storage of materials and use appropriate containers. Check that storage containers are correctly labelled and that incompatible materials, for example acids and caustics are separated.

Plan the storage and disposal of waste.


Exposure to hazardous substances can occur during cleaning, so plan and organise the workplace so that it can be easily and effectively cleaned. Smooth work surfaces will allow easy cleaning.

Have the right equipment and procedures to clear up spillages quickly and safely.

Clean regularly using a 'dust-free' method – vacuum, do not sweep.

Personal protective equipment

If you cannot adequately control exposure by other means, provide personal protective clothing and equipment, in combination with other control measures.

Do not automatically opt for personal protective equipment (PPE) as a control measure. It is not as reliable or effective as other measures.

More on PPE

Information and training

Workers need to understand the outcome of your risk assessment and what this means for them. Tell them what the hazards and risks are, and any workplace exposure limits, and what they need to do to protect themselves.

You must make workers aware of the results of any monitoring of exposure and the collective results of health surveillance.

Train workers to use controls and PPE correctly.

Workers should know what to do if there is an accident (for example spillage) or emergency.

Contractors in your workplace also need to know what the risks are and how you are controlling them. In addition, you need to know if they are bringing hazardous substances onto your premises, and how they will prevent harm to your workers.

More on information and training

Record your findings

If you have 5 or more employees, you must record your assessment but, even if you have fewer than 5, it makes sense to write down what steps you have taken to identify the risks. Make a list of the actions you have taken to control the risks to workers' health.

Review your controls

Review the risk assessment regularly to ensure it’s kept up to date and accounts for any changes in your workplace.

You must review the controls you have put in place to make sure they are working.

You should also review them if they may no longer be effective or there are changes in the workplace that could lead to new risks such as changes to:

  • staff
  • a process
  • the substances or equipment used

Also consider a review if your workers have spotted any problems or there have been any accidents or near misses.

Update your risk assessment record with any changes you make.

The law

If your business uses or creates substances, or carries out processes which might cause harm to health, the law requires you to control the risks to workers.

The Control of Substances Hazardous to Health Regulations (COSHH) apply to most harmful substances but lead and asbestos are covered by separate regulations. You can read the COSHH regulations on

If you manufacture or import chemicals you should read our guidance on the REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) Regulation.

If you manufacture, import or formulate chemicals for supply, you should read the Classification, Labelling and Packaging of substances and mixtures (CLP) Regulation.

If you transport chemicals, you should read the Carriage of Dangerous Goods and Use of Transportable Pressure Equipment Regulations.

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