COSHH Risk Assessments: Why Safety Data Sheets Are Not Enough

May 1, 2026

Many businesses think they are managing COSHH because they have a folder full of safety data sheets.

The folder may be neatly organised. The sheets may be up to date. The products may be labelled. Someone may even have created a list of chemicals used on site.

That is useful, but it is not the same as a COSHH risk assessment.

A safety data sheet tells you important information about a substance. It does not, on its own, tell you whether that substance is being used safely in your workplace.

That difference matters.

COSHH is not just about knowing that a substance is hazardous. It is about understanding how people could be exposed to it, what harm it could cause, whether the current controls are enough, and what needs to be done to prevent or adequately control exposure.

A safety data sheet may be the starting point. It should not be the finishing point.

What Does COSHH Mean?

COSHH stands for the Control of Substances Hazardous to Health Regulations.

The regulations are designed to protect workers and others from health risks caused by hazardous substances at work. The Health and Safety Executive’s main guidance on Control of Substances Hazardous to Health explains that COSHH involves identifying, assessing and controlling risks from hazardous substances in the workplace.

In plain English, COSHH is about stopping people becoming ill because of something they breathe in, touch, swallow, inject, or otherwise absorb during work.

That could involve chemicals, dusts, fumes, vapours, gases, mists, biological agents, cleaning products, paints, adhesives, oils, welding fumes, wood dust, flour dust, silica dust, metalworking fluids or many other substances.

Some hazardous substances are bought in as products. Others are created by the work itself.

That is one of the reasons COSHH is often misunderstood.

A business may look only at the bottles and containers it buys, but the greater risk may come from dust, fume, mist or vapour produced during a process.

Why Safety Data Sheets Matter

Safety data sheets are important.

They provide information about the hazards of a product, how it should be handled, storage requirements, exposure controls, personal protective equipment, first aid measures, accidental release measures and disposal considerations.

They can help you understand whether a substance is hazardous and what precautions may be needed.

However, a safety data sheet is usually written for a wide range of possible users and conditions. It is not specific to your workplace.

It does not know:

• how much of the substance you use
• how often you use it
• whether it is sprayed, brushed, poured, heated, mixed or wiped
• whether it is used in a small enclosed room or a well-ventilated area
• whether employees wear suitable gloves or the wrong type
• whether workers are trained
• whether containers are left open
• whether substances are mixed together
• whether local exhaust ventilation is present and working
• whether people are exposed for minutes or hours
• whether contractors, cleaners, visitors or members of the public could be affected

That is why the assessment still needs to be done.

A safety data sheet gives information. A COSHH assessment applies that information to the real work activity.

The Difference Between Hazard And Risk

A common COSHH mistake is confusing hazard with risk.

A hazard is the potential of something to cause harm.

Risk is the likelihood of harm occurring and the possible severity of that harm in the actual circumstances.

For example, a corrosive cleaning product is hazardous. But the level of risk will depend on how it is stored, handled, diluted, applied, controlled and supervised.

The same product might present a relatively low risk if it is used occasionally in small quantities by trained staff wearing suitable gloves and eye protection. It may present a much higher risk if it is decanted into unlabelled containers, mixed with other chemicals, used in confined areas, splashed during cleaning, or handled without suitable protection.

The substance has not changed. The risk has.

That is why COSHH assessments must focus on the work activity, not just the product label.

Exposure Is The Key Issue

COSHH is about exposure.

A hazardous substance only causes harm if someone is exposed to it in a way that allows it to enter or affect the body.

The HSE explains that exposure can occur through breathing in fume, dust, gas or mist, through skin contact, by injection into the skin, or by swallowing. Its guidance on workplace exposure limits is helpful because it explains both the routes of exposure and the role of exposure limits in protecting health.

In practice, the main routes to consider are:

• inhalation
• skin contact
• eye contact
• ingestion
• injection through cuts, punctures or high-pressure equipment

Inhalation is often a major concern where substances are airborne, such as dust, fume, gas, vapour or mist.

Skin contact can be just as important. Some substances cause dermatitis, burns, irritation or sensitisation. Others can be absorbed through the skin and affect the body internally.

Ingestion may occur when workers eat, drink or smoke with contaminated hands, or where poor hygiene arrangements allow substances to transfer from surfaces to the mouth.

Injection can occur through sharps, punctures, high-pressure fluid injection injuries or broken skin.

A good COSHH assessment should consider all relevant routes of exposure, not simply whether a product is labelled as hazardous.

Workplace Exposure Limits

Some hazardous substances have workplace exposure limits, often known as WELs.

These are limits for airborne concentrations of hazardous substances, averaged over a specified period. They are intended to help protect workers’ health.

If a substance has a WEL, the employer needs to consider whether exposure could exceed that limit and what controls are needed.

This may require more than visual judgement.

For example, a workplace may look reasonably clean but still have airborne exposure to dust, fume or vapour. A process may only run for part of the day, but short-term exposure may still be significant. A substance may have a low odour but still be harmful.

Where exposure cannot be confidently assessed by observation alone, air monitoring or occupational hygiene input may be needed.

This is especially relevant for substances such as welding fume, wood dust, silica dust, isocyanates, solvents and other airborne hazards.

COSHH Is Not Just About Chemicals

The name COSHH often makes people think only of chemicals in bottles.

That is too narrow.

COSHH can apply to many substances that are hazardous to health, including substances generated by work processes.

Examples include:

• wood dust from cutting, sanding or machining
• silica dust from cutting stone, brick, concrete or tiles
• welding fume
• flour dust
• metalworking fluid mist
• exhaust fumes
• solvent vapours
• paint mist
• biological agents
• cleaning chemical vapours
• fumes from soldering or hot work
• dust from demolition or refurbishment

This is where many businesses under-assess the risk.

They may have data sheets for cleaning products but no meaningful assessment of dust generated by their processes. They may have a chemical inventory but no assessment of welding fume. They may review product labels but not consider what happens when products are sprayed, heated or mixed.

A proper COSHH assessment looks at what workers are actually exposed to, not just what is stored in the cupboard.

Why “We Only Use Small Quantities” Is Not Always Enough

Quantity matters, but it is not the only factor.

A small amount of a highly hazardous substance may still create a serious risk. A small quantity used frequently may create repeated exposure. A small amount sprayed into the air may create greater inhalation risk than a larger amount kept sealed in a container.

The way the substance is used can be more important than the amount.

Consider the difference between:

• wiping a small amount of product onto a surface
• spraying the same product into the air
• heating it
• mixing it with another substance
• using it in a poorly ventilated space
• using it for several hours each day
• using it without suitable gloves or eye protection

The product may be the same, but the risk changes dramatically.

This is why COSHH assessments need to consider frequency, duration, concentration, method of use, ventilation, control measures and who may be exposed.

Control Measures Should Follow A Sensible Hierarchy

A common weakness in COSHH assessments is jumping straight to personal protective equipment.

Gloves, masks, goggles and protective clothing may be necessary, but they should not automatically be the first or only control.

Good COSHH management should consider whether the risk can be eliminated or reduced before relying on PPE.

That may include:

• avoiding the substance altogether
• substituting it with a less hazardous product
• changing the process to reduce exposure
• using closed systems
• improving ventilation
• using local exhaust ventilation
• reducing quantities
• reducing the number of people exposed
• improving storage and handling
• preventing spills and splashes
• improving hygiene arrangements
• maintaining equipment
• providing suitable training and supervision

PPE has limitations.

It must be correctly selected, fitted, worn, stored, maintained and replaced. Gloves need to be suitable for the specific substance. Respiratory protective equipment needs to be suitable for the hazard and may require face-fit testing. Eye protection must match the splash or impact risk.

If PPE is the only control, the business should be confident that it is suitable and that workers use it properly.

Local Exhaust Ventilation Must Be Managed

Where local exhaust ventilation, often called LEV, is used to control exposure, it needs to be properly designed, used, maintained and tested.

LEV can be an effective control for dusts, fumes, vapours and mists, but only if it captures the contaminant at source and continues to work properly.

Problems can arise when:

• the hood is too far from the source
• the airflow is insufficient
• workers do not position the work correctly
• filters are blocked
• ducting is damaged
• maintenance is poor
• testing is overdue
• employees do not understand how to use the system

A COSHH assessment should not simply state “LEV provided” and move on.

It should consider whether the LEV is suitable for the task and whether arrangements are in place to keep it effective.

Health Surveillance May Be Needed

In some situations, COSHH may require health surveillance.

Health surveillance is not the same as general wellbeing checks. It is used where there is a risk of identifiable work-related ill health and where surveillance can help detect early signs of harm.

Examples may include exposure risks linked to occupational asthma, dermatitis, certain chemicals, biological agents, or other substances where health effects can be monitored.

Health surveillance may include skin checks, respiratory questionnaires, lung function tests or other appropriate checks depending on the exposure.

The need for health surveillance depends on the risk and the substance involved.

A good COSHH assessment should identify whether health surveillance is required and what arrangements are needed.

Training Must Be Specific

COSHH training should be more than a generic course completed once.

Employees need to understand the specific substances and risks they face in their work.

They should know:

• what substances they use or may be exposed to
• what harm those substances can cause
• how exposure can occur
• what control measures are required
• how to use ventilation or extraction systems
• what PPE is needed and why
• how to check and use PPE correctly
• what to do if there is a spill, splash or exposure
• how to store substances safely
• how to dispose of waste
• when to report problems

Training should also challenge informal habits.

For example, workers may not realise that removing gloves incorrectly can contaminate skin. They may wear the wrong glove type. They may lift a mask to talk. They may leave lids open. They may mix cleaning chemicals without understanding the reaction risk.

Specific, practical training helps close the gap between the assessment and the way work is actually done.

COSHH Assessments Need To Reflect Reality

A COSHH assessment written from a desk may miss important issues.

The assessment should reflect how work is actually carried out.

That means looking at the task, speaking to employees, checking storage areas, observing how substances are handled, and reviewing whether control measures are actually used.

For example, the paperwork may say that a product is used in a well-ventilated area. But the task may actually be carried out in a small room with the door closed.

The assessment may say gloves are worn. But the gloves may be unsuitable for the chemical, reused when damaged, or removed halfway through the task.

The assessment may say that containers are labelled. But staff may decant products into unmarked bottles for convenience.

The assessment may say that exposure is low. But the task may be done far more frequently than managers realise.

These are the details that matter.

Storage, Labelling And Segregation

COSHH assessments should also consider how substances are stored and managed when not in use.

Poor storage can create exposure risks, spill risks and confusion.

Basic issues to consider include:

• are substances kept in suitable containers?
• are containers clearly labelled?
• are lids kept closed?
• are incompatible substances separated?
• are flammable substances stored correctly?
• are corrosive substances stored safely?
• are spill arrangements suitable?
• are old or unused substances removed?
• are quantities kept as low as reasonably practicable?
• are staff prevented from using unapproved substances?

Labelling is especially important where substances are decanted.

If a substance is poured into another container, the new container must not create confusion. Unlabelled bottles, food containers or informal storage arrangements can easily lead to misuse or accidental exposure.

Contractors And Visitors May Also Be Affected

COSHH does not only concern employees.

Contractors, cleaners, maintenance workers, temporary staff and visitors may also be affected by hazardous substances.

A contractor carrying out hot work, maintenance or cleaning may disturb residues, dusts or substances that regular employees do not normally encounter. A cleaner may use products in a different way from normal staff. A visitor may enter an area where exposure is possible.

Businesses should also consider substances brought onto site by contractors.

For example, a contractor may bring adhesives, paints, solvents, gases or cleaning chemicals. The business still needs to coordinate risks and make sure work is controlled.

COSHH management should therefore link with contractor control, permit-to-work systems, induction and communication.

When COSHH And DSEAR Overlap

Some substances create both health risks and safety risks.

A solvent may create an inhalation risk under COSHH and a flammable vapour risk under DSEAR. A dust may create respiratory risk under COSHH and explosion risk under DSEAR. A gas may be toxic, flammable, pressurised or all three.

This means COSHH and DSEAR assessments may need to sit alongside each other.

They do not replace each other.

COSHH asks: how could this substance harm health through exposure?

DSEAR asks: could this substance create fire, explosion, pressure or related safety risks?

Both questions may be relevant.

Reviewing COSHH Assessments

COSHH assessments need to be reviewed when things change.

That may include:

• new substances
• new processes
• changes in quantities
• changes in frequency or duration of use
• new equipment
• changes in ventilation
• new safety data sheets
• incidents or near misses
• reports of ill health
• changes in staff or working practices
• evidence that controls are not working

A review does not always mean starting again. It may mean checking whether the existing assessment is still valid and updating the parts that have changed.

However, if a COSHH assessment has not been looked at for years, it is sensible to question whether it still reflects reality.

Products change. Processes change. Suppliers update safety data sheets. Employees find shortcuts. Controls deteriorate. Workloads increase.

A current assessment is far more valuable than an old one sitting untouched in a folder.

Common COSHH Failings

Many COSHH failings are practical rather than technical.

Common problems include:

• relying only on safety data sheets
• failing to assess substances created by work processes
• missing skin exposure
• assuming PPE solves everything
• using unsuitable gloves or masks
• failing to maintain extraction systems
• not checking exposure levels where needed
• poor storage and labelling
• lack of employee training
• no health surveillance where required
• outdated assessments
• failing to review changes
• not involving employees in the assessment process

These failings matter because they can lead to real harm.

COSHH-related illness is not always immediate. Some effects build up over time. Workers may develop dermatitis, asthma, respiratory disease or other long-term health problems after repeated or poorly controlled exposure.

That is why COSHH should not be treated as a minor paperwork issue.

What A Good COSHH Assessment Looks Like

A good COSHH assessment should be clear, specific and practical.

It should identify the hazardous substance or process, explain the health risks, consider who may be exposed, assess how exposure could occur, and record the control measures needed.

It should be written in a way that managers and employees can understand.

It should also be connected to action.

If the assessment identifies that better ventilation is needed, that must become an action. If gloves are required, the right type needs to be selected and provided. If training is needed, it should be delivered. If health surveillance is required, arrangements must be made. If exposure monitoring is needed, it should be planned.

The assessment should not sit separately from the workplace. It should shape how the work is actually controlled.

What Businesses Should Do Next

If you are unsure whether your COSHH arrangements are suitable, start with a practical review.

Ask:

• what substances do we buy, store, use or create?
• are any hazardous to health?
• do we have current safety data sheets?
• how are substances actually used?
• who could be exposed?
• how could exposure occur?
• are our control measures suitable?
• do we rely too heavily on PPE?
• are gloves, masks or extraction systems suitable?
• do we need exposure monitoring?
• do we need health surveillance?
• are employees properly trained?
• have we reviewed changes?

This does not need to be complicated, but it does need to be honest.

The most important question is not “do we have a COSHH folder?”

It is “are people properly protected from exposure?”

You could also ask us having looked at our experience providing COSHH assessments.

Final Thought

Safety data sheets are useful, but they are not COSHH assessments.

They provide information about hazardous substances, but they do not assess the way those substances are used in your workplace. They do not confirm whether exposure is controlled. They do not check whether employees understand the risks. They do not prove that gloves, masks, ventilation or procedures are suitable.

A proper COSHH risk assessment goes further.

It considers the substance, the task, the exposure route, the people affected, the control measures, the training, the monitoring and the review process.

Done properly, COSHH is not just a folder of documents. It is a practical system for preventing ill health.

That is why safety data sheets are only the starting point.

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