UK / General HSE Article
COSHH starts with exposure, not paperwork
A COSHH assessment connects a hazardous substance to the real task. It explains what can harm people, how exposure can happen and what controls are needed before work is allowed to continue.
Most workplaces use substances that can harm health. Some are obvious, like acids, solvents, oils, paints, adhesives and cleaning chemicals. Others are created by the work, such as dust, fume, vapour, mist or waste residue. A COSHH assessment should not be a copied safety data sheet. It should explain how people may be exposed during the actual job and what needs to be done to control that exposure.
Look at how the substance is really used
The same product can create different risks depending on how it is used. A small amount of cleaner used with good ventilation may be low risk. The same product sprayed repeatedly in a small room can become a breathing and skin exposure problem. Watch the task: pouring, mixing, spraying, wiping, heating, cleaning, spilling and disposing all matter.
- Check the amount used, how often it is used and how long exposure lasts.
- Look at normal use and less tidy work such as spills and cleaning.
- Include workers nearby if vapour, mist, dust or fume can spread.
Use the safety data sheet properly
The safety data sheet gives important product information, including hazards, first aid, storage, handling and exposure controls. It does not know your workplace. It does not know whether the worker is spraying, brushing, mixing, cleaning or using the substance in poor ventilation. Use the data sheet as evidence, then apply it to the task.
- Check the SDS is for the exact product and latest available version.
- Read the first aid, handling, storage and exposure control sections.
- Do not copy long phrases if they do not explain your workplace control.
Identify the routes of exposure
People may breathe in dust, fumes, vapours, gases or mists. They may get substances on skin or in eyes. They may swallow contamination from hands, food, drink or poor hygiene. Some substances can enter through cuts or high-pressure injection. The assessment should say which routes are realistic for the task.
- Consider inhalation, skin contact, eye contact, ingestion and injection where relevant.
- Check gloves, handles, benches, rags, tools and waste containers for contamination.
- Think about maintenance and cleaning staff as well as operators.
Choose controls before PPE
COSHH control should prevent or reduce exposure. PPE can be part of the answer, but it should not be the whole system. Safer products, closed transfer, local exhaust ventilation, smaller containers, dosing systems, wet methods, good storage and clear hygiene rules may give stronger protection than gloves and masks alone.
- Consider whether the substance can be removed or substituted.
- Use enclosure, extraction or better application methods where exposure is created.
- Specify PPE carefully, including glove material, eye protection and respiratory protection where needed.
Include storage, labelling and waste
Poor COSHH control often appears away from the main task. Unlabelled bottles, incompatible storage, damaged containers, dirty rags, leaking drums and poor waste disposal can create exposure and emergency risks. A good assessment covers the full life of the substance on site.
- Keep labels clear and containers suitable.
- Do not decant into unmarked bottles.
- Set clear arrangements for spills, contaminated waste and empty containers.
Make training task-specific
Workers do not need a chemistry lecture, but they do need to know what the substance can do, how exposure may happen during their task, which controls must be used and what to do if something goes wrong. Training should match the product, task and workplace controls.
- Explain the health effects that matter for the job.
- Show how controls, PPE and hygiene rules must be used.
- Tell workers what to do after a spill, splash, breathing concern or skin reaction.
COSHH terms worth understanding
These terms help you read an assessment and question whether exposure is controlled properly.
Hazardous substance
A product or substance created by work that can harm health, such as chemicals, dust, fume, vapour, mist, biological agents or waste residue.
Exposure
Contact between the substance and the person. Exposure may happen by breathing, skin contact, eye contact, swallowing or injection.
Substitution
Replacing a hazardous substance or process with a safer option where reasonably practicable.
Local exhaust ventilation
Extraction designed to capture airborne contamination close to where it is produced before workers breathe it in.
Health surveillance
Checks used where there is a remaining health risk that needs monitoring, such as skin checks for dermatitis risk.
COSHH assessment check
- The exact substance and task are described
- The safety data sheet has been reviewed
- Exposure routes are identified
- Controls are higher than PPE where possible
- Storage, spills and waste are covered
- Workers know what to do if exposure occurs
COSHH mistakes to avoid
- Copying the safety data sheet and calling it an assessment
- Forgetting dust, fume and substances created by work
- Writing ‘wear gloves’ without checking glove suitability
- Ignoring cleaning, spills and disposal
- Using the same assessment for very different tasks
What a good COSHH assessment should achieve
After reading the assessment, a supervisor should be able to explain how exposure will be prevented or controlled. A worker should be able to understand what they must use, what they must avoid and what they should report.