How to Carry Out a COSHH Risk Assessment: A Step-by-Step Guide for UK Employers
If you use hazardous substances in your workplace, a COSHH risk assessment is not optional. Under the Control of Substances Hazardous to Health Regulations 2002 , UK employers must assess the risks before work with those substances begins. Not after an incident. Not when an inspector asks.
On this page
- What is a COSHH Risk Assessment?
- Step 1: Identify the Hazardous Substances in Your Workplace
- Step 2: Consider Who Might Be Harmed and How
- Step 3: Evaluate the Risks and What is Already in Place
- Step 4: Put Controls in Place
- Step 5: Record Your Findings
- Step 6: Review It
- Mistakes That Undermine COSHH Assessments
- Frequently asked questions
Most of the information you need already exists in the Safety Data Sheet for each substance. What a COSHH assessment adds is context: how your team actually uses the substance, how much exposure is realistic, and what controls will bring that risk down to an acceptable level.
What is a COSHH Risk Assessment?
A COSHH risk assessment is a documented evaluation of the health risks posed by hazardous substances in your specific workplace. The HSE sets out four core requirements: identify the substances, assess the risks, put controls in place, and review them over time. It is not the same thing as a Safety Data Sheet. The SDS describes the hazards of a substance as supplied by the manufacturer. The COSHH assessment applies those hazards to your people, your tasks and your environment. A business that hands workers an SDS and considers that job done is not compliant.Step 1: Identify the Hazardous Substances in Your Workplace
Start with a complete list of every substance your team works with that could cause harm. This is usually broader than employers expect. It covers:- Chemicals bought directly: solvents, cleaning products, adhesives, fuels, paints
- Substances generated during work: welding fumes, dust from cutting or sanding, exhaust gases
- Biological agents: bacteria, viruses and moulds depending on the type of work
- Substances brought onto site by contractors or left by previous tenants
Step 2: Consider Who Might Be Harmed and How
Exposure does not only affect the person directly handling a substance. Work through who else might be in the area:- Workers using the substance in their regular tasks
- Colleagues nearby who may be exposed through airborne contamination or incidental skin contact
- Cleaners, maintenance staff and contractors who work in the same spaces
- Visitors, and anyone particularly vulnerable such as new or expectant mothers
Step 3: Evaluate the Risks and What is Already in Place
Bring together what you know about the substance and how your team works with it. The relevant question is not whether the substance is inherently dangerous. It is whether the level of exposure in your workplace is acceptable given current controls. Go through each substance and task and ask:- How long are workers typically exposed, and how often?
- What controls are already in place: ventilation, containment, PPE?
- Are those controls being used correctly and consistently?
- Are some workers more at risk than others?
Step 4: Put Controls in Place
Where the assessment shows current controls are not adequate, you need better ones. The COSHH regulations set out a hierarchy of controls in order of effectiveness:- Eliminate: remove the substance entirely and substitute it with something safer
- Control at source: use enclosures, local exhaust ventilation, or redesign the process to cut exposure at the point it is generated
- Reduce exposure: safe working procedures, smaller quantities, fewer people involved
- Personal protective equipment: gloves, respirators, goggles, as the final layer of protection, not the primary one
Step 5: Record Your Findings
Employers with five or more workers are legally required to record the significant findings of a COSHH assessment. Even with fewer employees, a written record is good practice and protects you if questions arise later. A useful record covers:- The substance and the specific tasks where it is used
- Who is at risk and the nature of exposure
- The controls in place and how their effectiveness is checked
- Whether health surveillance is required
- The assessment date and who carried it out
Step 6: Review It
A COSHH assessment is a working document, not a one-off exercise. Review it when:- A new substance arrives on site
- A process or working method changes
- Controls are found not to be working
- A worker reports a health concern that may relate to exposure
- The manufacturer issues a revised SDS for a substance in your assessment
Mistakes That Undermine COSHH Assessments
- Using the SDS as the assessment. The SDS provides the hazard information. The assessment is what you do with it.
- Copying from a generic template. An assessment must reflect your workplace, your tasks and your people. A downloaded template filled in quickly is not a risk assessment.
- Assessing the substance but ignoring the task. The same substance can represent very different levels of risk depending on how it is used. Bleach in a sealed bottle is not the same situation as bleach being decanted in a small unventilated space.
- PPE as the only control. If personal protective equipment is your primary answer to a hazardous substance, review the assessment.
- Never reviewing. An assessment from several years ago on a substance with a revised SDS may no longer be accurate. Review triggers exist for a reason.
- Keeping documents somewhere workers cannot reach. A folder in a manager’s office is not accessible to someone on the shop floor who needs it during an incident. The people who work with hazardous substances need to know where the SDS is and be able to get to it.
Once your SDS library and risk assessments are in order, many workplaces find the next step is making sure workers are properly trained to handle hazardous substances safely. ISDSS is part of the Safety-verse alongside The Knights of Safety Academy (TKOS), which provides COSHH compliance and chemical safety training. For workplaces that need both the documentation and the training to sit alongside each other, ISDSS and TKOS cover both sides of that.
Frequently Asked Questions
Who can carry out a COSHH risk assessment?
A competent person with the knowledge and experience to identify hazards, assess risk and recommend controls. That may be the employer, a health and safety professional, or another suitably trained employee.
Does every hazardous substance need its own assessment?
Not always. Similar substances used the same way, with comparable hazards and controls, can sometimes share a single assessment, but each should still be considered individually before deciding that.
Is an SDS the same as a COSHH risk assessment?
No. The SDS describes a chemical's hazards as supplied by the manufacturer. The assessment applies that information to how the substance is actually used in your workplace and what controls it needs.
How long should COSHH assessment records be kept?
There's no standard retention period. Keep assessments up to date and retain older records where they support health surveillance, exposure monitoring or evidence of compliance.
What happens if an assessment isn't carried out?
Possible HSE enforcement, including improvement notices, prohibition notices or prosecution, and a real risk of employees being exposed to hazardous substances without proper controls in place.
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