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

For each substance, you need the current Safety Data Sheet. The SDS is where the hazard classification, exposure limits and first aid information live. If you are missing documents, ISDSS provides free access to over two million Safety Data Sheets, searchable by product name or manufacturer.

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

For each group, think about how exposure actually happens. Skin contact during handling? Inhalation of vapour or dust? Ingestion through contaminated surfaces? Section 8 of the SDS covers exposure routes and workplace exposure limits and is the right starting point for this part of the assessment.

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?

ISDSS generates a Chemical Risk Assessment alongside each SDS in the database. This provides a task-based risk overview as a starting point that you can adapt to your own workplace conditions. For each substance and task it covers, the CRA helps you identify the PPE required, determine safe handling procedures, plan emergency responses and build a documented evidence trail for compliance.

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

PPE often appears first in workplace responses to chemical risks. It should appear last. It is there to handle residual risk after the controls above have already been applied. An assessment that lists PPE as the only measure for a substance with significant health risks will not survive scrutiny.

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

A two-page document that is clear and used is worth more than a twenty-page document that sits in a folder.

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

Revised SDS documents matter more than most employers realise. When a manufacturer updates the hazard classification, the exposure limits or the PPE requirements for a substance, your assessment may no longer reflect current guidance. Checking the revision date on ISDSS against the version your assessment references is a quick way to spot when a review is due.

⚠️ 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.