What Should a COSHH Assessment Include?

A COSHH assessment should identify how substances hazardous to health could cause harm in the workplace and establish the measures needed to prevent or adequately control exposure.

It should consider more than the hazardous properties of a chemical. A suitable assessment looks at the substance, the task, who could be exposed, how exposure could occur and whether existing controls are effective.

A Safety Data Sheet (SDS) can provide important hazard information, but it is not a COSHH assessment. The assessment needs to apply that information to the way the substance is actually used or generated within your workplace.

What information should a COSHH assessment contain?

The amount of detail required will depend on the substance and complexity of the work, but an assessment will typically need to consider:

• The hazardous substance or agent
• Potential health effects
• The activity or process involved
• Who could be exposed
• Routes of exposure
• Frequency and duration of exposure
• Relevant workplace exposure limits (WELs)
• Existing control measures
• Whether further controls and required
• PPE and RPE, where appropriate
• Exposure monitoring or health surveillance requirements
• Emergency arrangements
• Information, instruction and training
• Actions and responsibilities
• Review arrangements

Ultimately, the assessment should establish whether people are adequately protected from exposure to substances that could harm their health.

1. Identify the hazardous substance

The assessment should identify the substance or hazardous agent involved and the activity in which it is used.

For chemical products, the product label and current Safety Data Sheet are useful sources of information.

However, COSHH is not limited to packaged chemicals. Hazardous substances can also be generated by workplace processes.

Examples include:

• Welding fume
• Wood dust
• Silica-containing dust
• Metalworking fluid mist
• Vapours and fumes generated during processes

Our guide to what substances are covered by COSHH explains the different types of hazardous substances employers may need to consider.

2. Understand the potential health effects

The assessment should establish how the substance could affect health.

Depending on the substance and exposure involved, potential effects could include skin or eye irritation, dermatitis, occupational asthma, respiratory conditions, sensitisation and other acute or long-term health effects.

It is important to distinguish between the hazard presented by a substance and the risk created by the activity.

The same hazardous product may create very different risks depending on how it is used.

3. Consider the activity and potential exposure

A COSHH assessment should reflect what actually happens in the workplace.

For example, rather than simply recording "use of solvent cleaner", the assessor may need to understand whether the product is applied manually, sprayed, used in an open container or used within enclosed equipment.

Considerations can include:

• How much is used
• How frequently the activity takes place
• How long the activity lasts
• Whether dust, fumes, vapours or mists are generated
• How close employees are to the source
• Whether work takes place in a confined or poorly ventilated area

These factors help establish the potential level of exposure.

4. Identify who could be exposed

The assessment should consider everyone who could reasonably be exposed, not just the employee carrying out the task.

This could include:

• Operators
• Employees working nearby
• Maintenance personnel
• Cleaners
• Contractors
• Supervisors
• People carrying out non-routine activities

The employer retains overall responsibility for managing COSHH risks, although individual duties may be assigned to managers, employees or competent advisers. Our guide to who is responsible for COSHH in the workplace explains these responsibilities further.

5. Consider the routes of exposure

The assessment should establish how the hazardous substance could enter or affect the body.

Common routes include:

Inhalation – breathing in dusts, fumes, gases, vapours or mists.

Skin contact – direct contact during use, handling, maintenance or cleaning.

Eye contact – exposure from splashes, sprays, dust or contaminated hands.

Ingestion – transferring hazardous substances from contaminated hands or surfaces to the mouth.

Understanding the route of exposure helps determine which controls are appropriate.

6. Check relevant Workplace Exposure Limits

Some hazardous substances have a Workplace Exposure Limit (WEL). The HSE publishes the current GB Workplace Exposure Limits in EH40 Workplace Exposure Limits.

Where relevant, the assessment should identify the applicable limit and consider whether existing controls are capable of adequately controlling exposure.

A WEL should not simply be treated as a target exposure level. Exposure should still be prevented where reasonably practicable and otherwise adequately controlled.

7. Assess the existing control measures

The assessment should record and evaluate the measures already being used to prevent or control exposure.

These could include:

• Substitution with a safer product or process
• Enclosure
• Local exhaust ventilation (LEV)
• General ventilation
• Automation or isolation
• Safe working procedures
• Hygine arrangements
• PPE
• RPE

The important point is to consider whether the controls are effective in practice, rather than simply noting that they exist.

For example, having LEV installed does not automatically mean exposure is adequately controlled. It needs to be suitable for the process, used correctly and maintained effectively.

8. Consider whether further controls are needed

Where exposure cannot be prevented, the assessment should determine whether it is adequately controlled.

Before relying on PPE, employers should consider whether the risk can be reduced through measures such as changing the substance, modifying the process, enclosure or engineering controls.

Where PPE or RPE is required, the equipment needs to be suitable for the substance, task and exposure involved.

9. Consider non-routine activities

Maintenance, cleaning and breakdown activities can sometimes result in higher exposure than normal production.

The assessment should therefore consider foreseeable activities such as:

• Cleaning equipment
• Changing filters
• Clearing blockages
• Opening enclosed machinery
• Maintenance and repairs
• Spill response
• Waste handling

These tasks can easily be overlooked if an assessment considers only routine operation.

10. Consider monitoring, health surveillance and emergencies

Depending on the substance and exposure, additional measures may be required.

This could include workplace exposure monitoring to determine whether controls are effective or health surveillance to help identify signs of work-related ill health.

The assessment should also consider foreseeable incidents such as spills, leaks, accidental releases or control failures and establish appropriate arrangements where necessary.

11. Record actions, training and review requirements

Where improvements are required, the assessment should clearly identify what needs to be done, who is responsible and when actions should be completed.

Employees should also receive appropriate information, instruction and training so they understand the hazards, controls and precautions relevant to their work.

Finally, the assessment needs to remain current.

A review may be necessary where there are significant changes to substances, processes, equipment or control measures, where new hazard information becomes available or where there is reason to believe the existing assessment is no longer valid.

Is a Safety Data Sheet enough for COSHH?

No. A Safety Data Sheet is an important source of hazard information, but it does not assess the circumstances within your workplace.

An SDS cannot, on its own, determine how frequently your employees use the product, how much they use, whether it is sprayed or poured, the effectiveness of your extraction or whether other people could be exposed.

A COSHH assessment should therefore use relevant information from the SDS while considering the actual task, exposure and controls within the workplace.

What does a good COSHH assessment look like?

A good COSHH assessment should be specific, practical and proportionate to the risk.

It should allow someone familiar with the work to understand:

• What the hazard is
• Who could be exposed
• How exposure could occur
• What controls are required
• Whether existing controls are adequate
• What further action is needed

Most importantly, it should reflect what actually happens in the workplace rather than simply repeating generic information from a Safety Data Sheet.

For organisations managing numerous hazardous substances or more complex exposure scenarios, Spiers Safety provides COSHH assessment and hazardous substance management services to help assess workplace activities, evaluate existing controls and establish practical measures for managing exposure.