Do you use or store hazardous substances at work?
Quick check to determine if COSHH applies to you
Why COSHH matters
Every year in the UK, thousands of workers develop serious health conditions from exposure to hazardous substances at work. Many of these diseases are preventable with proper assessment and control.
Unlike accidents that happen suddenly, exposure to hazardous substances often causes harm slowly over months or years — by the time symptoms appear, the damage is done.
Under the Control of Substances Hazardous to Health Regulations 2002 (COSHH), employers must assess risks from hazardous substances and put controls in place to protect workers' health. Failure to comply can result in unlimited fines, imprisonment, and civil claims from injured workers.
What is COSHH?
COSHH stands for Control of Substances Hazardous to Health. The COSHH Regulations 2002 require employers to control substances that are hazardous to health.
This isn't just about obviously dangerous chemicals. COSHH covers a huge range of substances found in almost every workplace:
- Chemicals and products containing chemicals
- Fumes from welding, soldering, or burning
- Dusts from wood, flour, silica, or other materials
- Biological agents like bacteria and viruses
- Vapours from paints, solvents, or adhesives
Many everyday products are hazardous under COSHH. Bleach, oven cleaner, printer toner, and paint stripper are all examples of common workplace substances that require COSHH assessment.
What substances are covered?
COSHH covers substances that are hazardous to health. A substance is hazardous if it can harm people's health when they are exposed to it.
Types of hazardous substances
| Category | Examples | Common Workplaces |
|---|---|---|
| Cleaning chemicals | Bleach, descalers, oven cleaners, disinfectants | Offices, shops, care homes, schools |
| Solvents & adhesives | White spirit, paint thinners, glues, resins | Manufacturing, construction, garages |
| Paints & coatings | Oil-based paints, spray paints, varnishes, powder coatings | Painters, manufacturers, bodyshops |
| Dusts | Wood dust, flour dust, silica, asbestos | Workshops, bakeries, construction |
| Fumes | Welding fumes, soldering fumes, diesel exhaust | Manufacturing, garages, construction |
| Biological agents | Bacteria, viruses, moulds, used needles | Healthcare, waste, agriculture, labs |
| Gases | Carbon monoxide, chlorine, LPG, carbon dioxide | Manufacturing, swimming pools, welding |
This is not exhaustive. If a substance can harm health, it's covered by COSHH.
How to tell if a substance is hazardous
- Check the label — hazard pictograms (diamonds with symbols) indicate hazardous substances
- Request the Safety Data Sheet (SDS) — suppliers must provide this for hazardous substances
- Consider what's created — even if you don't use hazardous substances, your processes may create them (dust, fumes, vapours)
Some substances are so dangerous they're subject to additional regulations beyond COSHH — including asbestos, lead, and certain carcinogens. If you work with these, specialist advice is essential.
What substances are NOT covered by COSHH?
COSHH doesn't cover:
- Asbestos or lead (covered by separate regulations)
- Radioactive materials (covered by separate regulations)
- Medicines to patients (covered by separate regulations)
- Explosives or flammable substances purely in relation to fire/explosion risk (covered by other laws)
However, even if a substance is excluded from COSHH for one reason, you may still need to assess other hazards under COSHH. For example, petrol is covered by dangerous substances regulations for fire risk, but COSHH still applies to health risks from vapour inhalation.
COSHH assessment requirements
Before you use any hazardous substance, you must carry out a COSHH assessment. This is a legal requirement.
What is a COSHH assessment?
A COSHH assessment is a careful examination of what could cause harm to people's health in your workplace, so you can weigh up whether you have taken enough precautions or should do more to prevent harm.
The assessment must be:
- Suitable and sufficient — covering the actual risks in your workplace
- Recorded — if you have 5 or more employees
- Reviewed regularly — and updated when things change
- Actioned — you must implement the control measures identified
A COSHH assessment isn't just paperwork. It's about identifying real risks and putting real controls in place to protect workers' health.
Who can do a COSHH assessment?
The person doing the assessment must be competent — they need adequate training, knowledge, and experience to:
- Identify the hazards
- Understand the risks
- Know what control measures are appropriate
- Implement and monitor those controls
For simple, low-risk substances (like basic cleaning products used as directed), an informed employer or manager can often do the assessment. For complex substances, hazardous processes, or high-risk situations, you may need specialist occupational hygiene advice.
Should you DIY or hire a specialist?
Do It Yourself
- •Simple, low-risk substances
- •Used strictly as directed
- •Clear Safety Data Sheets available
- •Standard control measures adequate
- •You understand the risks
- •Cost: Free (your time)
Hire a Specialist
Recommended- •Complex chemical processes
- •High-risk substances
- •Significant exposure potential
- •Uncertain about controls
- •Need exposure monitoring
- •Cost: £300-1,500+
Bottom line: For straightforward substances used as intended (like standard cleaning products), employers can often do their own assessments. For complex processes, high-risk substances, or situations requiring exposure monitoring, professional occupational hygiene advice is essential.
The 8 steps of COSHH compliance
Follow these 8 steps to comply with COSHH:
Identify hazardous substances and evaluate the risks to health
Eliminate, substitute, or control exposure using the hierarchy of controls
Implement engineering controls, ventilation, safe systems of work
Ensure workers use controls correctly and report problems
Check that controls are working and exposure is below limits
Monitor workers' health if required for specific substances
Have procedures and equipment ready for spills, leaks, and incidents
Tell workers about risks, controls, and safe working procedures
The hierarchy of control
When deciding what controls you need, always follow this order of priority:
- Elimination — stop using the substance entirely if possible
- Substitution — replace with something less hazardous
- Engineering controls — enclose the process, use local exhaust ventilation (LEV)
- Administrative controls — reduce exposure time, rotate workers, safe systems of work
- PPE — respiratory protection, gloves, protective clothing (last resort, not first choice)
Personal protective equipment (PPE) should be the last line of defence, not the first. If you can eliminate or control the risk in other ways, you must do so. PPE is acceptable only where other controls are not reasonably practicable or as an interim measure.
Safety Data Sheets explained
Safety Data Sheets (SDS), sometimes called Material Safety Data Sheets (MSDS), are your key source of information for COSHH assessments.
What is a Safety Data Sheet?
An SDS is a detailed document provided by the supplier of a hazardous substance. It contains:
- Hazard identification — what dangers the substance poses
- Composition — what chemicals it contains
- First aid measures — what to do if someone is exposed
- Fire-fighting measures — how to deal with fires involving the substance
- Handling and storage — how to use and store it safely
- Exposure controls/PPE — what controls and protective equipment to use
- Physical and chemical properties — appearance, odour, flash point, etc.
- Toxicological information — health effects from exposure
- Ecological information — environmental hazards
- Disposal considerations — how to dispose of safely
- Regulatory information — legal classification and labelling
- Other information — date issued, revisions, etc.
Your responsibilities
- Obtain SDS before using a substance — ask your supplier
- Read and understand the SDS — don't just file it away
- Use SDS information in your COSHH assessment — it tells you what controls you need
- Keep SDS accessible — workers need to be able to consult them
- Get updated SDS — when formulations change or regulations update
Suppliers must provide a Safety Data Sheet for any substance classified as hazardous. If they don't provide one, ask for it. If they refuse, reconsider whether to use that supplier.
COSHH by sector
Different industries have different COSHH challenges:
| Sector | Common Hazards | Key Controls |
|---|---|---|
| Cleaners | Bleach, descalers, disinfectants, trigger sprays | Dilution, ventilation, gloves, eye protection, training |
| Painters & Decorators | Solvents, paint fumes, spray mists, strippers | LEV, RPE, substitution, skin protection, hygiene |
| Manufacturing | Chemicals, dusts, fumes, oils, coolants | Enclosed processes, LEV, PPE, monitoring, health surveillance |
| Healthcare | Disinfectants, drugs, biological agents, sterilants | Safe handling procedures, PPE, sharps disposal, vaccination |
| Garages & Bodyshops | Spray paints, brake dust, solvents, welding fumes | Spray booths, LEV, RPE, skin protection |
| Construction | Silica dust, cement, solvents, bitumen fumes, wood dust | Water suppression, LEV, RPE, hygiene facilities |
| Hairdressers | Hair dyes, bleaches, perm solutions, aerosols | Gloves, ventilation, skin checks, product choice |
This is general guidance. Your specific COSHH requirements depend on what substances you actually use and how you use them.
Workplace Exposure Limits (WELs)
For many hazardous substances, the government sets Workplace Exposure Limits (WELs). These are maximum concentrations of substances in the air, averaged over a set time period, that are considered acceptable.
Types of exposure limits
- Long-term (8-hour TWA) — time-weighted average over 8 hours
- Short-term (15-minute STEL) — short-term exposure limit over 15 minutes
Your COSHH assessment must ensure exposure stays below these limits. If you can't be sure, you need to monitor exposure by measuring substance concentrations in the workplace air.
Staying below the WEL doesn't automatically mean you're safe. The regulations require you to reduce exposure to as low as reasonably practicable, even if you're below the limit.
When you need exposure monitoring
You must monitor exposure when:
- You can't be certain exposure is adequately controlled
- The COSHH assessment identifies a substance where monitoring is required
- You're working with specific high-risk substances listed in COSHH regulations
- You're relying on RPE or LEV to control exposure to certain substances
Exposure monitoring usually requires specialist equipment and expertise.
Health surveillance
For some substances and processes, you must provide health surveillance — regular health checks to detect early signs of work-related ill health.
When health surveillance is required
Health surveillance is required when:
- Workers are exposed to substances known to cause specific diseases or health effects
- There are valid techniques for detecting early signs of disease
- There's a reasonable likelihood that disease may occur under the conditions at your workplace
- Surveillance is likely to benefit workers' health
Common examples include:
- Respiratory questionnaires and lung function tests for those exposed to respiratory sensitisers
- Skin checks for those exposed to skin sensitisers or irritants
- Biological monitoring for substances absorbed through skin or lungs
Who can carry out health surveillance?
Depending on the substance and required surveillance:
- Simple questionnaires and checks can be done by a trained responsible person
- Medical surveillance requires a qualified occupational health professional
- Biological monitoring requires laboratory analysis
Health surveillance records must be kept for at least 40 years for many substances. If you provide health surveillance, ensure you have systems to maintain these records even if workers leave or your business changes.
Common questions
Yes. Many cleaning products are classified as hazardous (bleach, descalers, oven cleaners, etc.). You need to assess the risks and put controls in place. The good news is that for products used as directed by the manufacturer, the assessment is often straightforward. Check the Safety Data Sheet and follow the manufacturer's instructions for safe use.
Review your COSHH assessments regularly — at least annually is good practice. You must also review whenever there's reason to suspect the assessment is no longer valid: after changes to substances used, changes to processes or quantities, after health surveillance identifies problems, or if controls fail. If in doubt, review it.
A COSHH assessment is a specific type of risk assessment focused on hazardous substances. While general risk assessments cover all workplace hazards (slips, trips, machinery, etc.), COSHH assessments specifically examine risks from substances hazardous to health. You need both — COSHH assessments for hazardous substances, and general risk assessments for other workplace risks.
Yes. Even if you only use a hazardous substance occasionally, you still need to assess the risks. Occasional use doesn't eliminate the hazard. However, infrequent low-level use may require less complex controls than daily high-exposure use. The assessment will help you determine what's appropriate.
No. PPE should be the last resort, not the first choice. The law requires you to follow the hierarchy of control: eliminate, substitute, or control the hazard before resorting to PPE. PPE is acceptable only where other controls aren't reasonably practicable, or as temporary protection while better controls are being put in place.
HSE can issue improvement notices requiring you to fix problems, prohibition notices stopping work until it's safe, and prosecute for serious failures. Penalties include unlimited fines and up to 2 years imprisonment. Additionally, workers who suffer ill health from exposure can sue for compensation. Prevention is always cheaper than the consequences.
Absolutely. COSHH applies to substances created by your work processes, not just products you buy. Wood dust, welding fumes, flour dust, exhaust fumes, and many other process-generated substances are hazardous to health and require COSHH assessment. Don't overlook what your work creates.
Keep COSHH assessment records for as long as they're current, plus at least 3 years after they're superseded (good practice). However, exposure monitoring and health surveillance records must be kept for at least 40 years for many substances, or 5 years for others. Check the regulations for your specific substances.
Only as a starting point. COSHH assessments must be specific to your workplace and how you use substances. An assessment from elsewhere may not reflect your processes, quantities, ventilation, or controls. You're responsible for ensuring your assessment is suitable and sufficient for your actual situation.
Real enforcement examples
Manufacturing company fined £120,000 for solvent exposure
A manufacturing company in the Midlands was prosecuted after HSE inspectors found workers regularly exposed to high levels of solvent vapours without adequate control.
- ✗No COSHH assessment for solvent-based processes
- ✗No local exhaust ventilation provided
- ✗Workers relying solely on disposable dust masks (inadequate for vapours)
- ✗No exposure monitoring ever carried out
- ✗Workers reporting headaches and dizziness regularly
The company was fined £120,000 plus £25,000 costs. They were required to install LEV systems, provide proper respiratory protection, and conduct exposure monitoring and health surveillance.
COSHH is not optional. Where significant exposure occurs, you must provide proper controls. Relying on inadequate PPE is a breach of the regulations and puts workers' health at serious risk. The cost of compliance is far less than the cost of enforcement and compensation claims.
Source: Based on HSE prosecution records
Garage owner prosecuted after worker develops occupational asthma
A garage owner was prosecuted after a spray painter developed occupational asthma from exposure to isocyanates in two-pack paint.
- ✗No COSHH assessment for spray painting activities
- ✗Spray booth ventilation inadequate and not tested
- ✗No air-fed respiratory protection provided (required for isocyanates)
- ✗No health surveillance programme for workers exposed to isocyanates
- ✗Worker continued working until symptoms became severe
The owner was fined £60,000 and ordered to pay £30,000 compensation to the worker, who could no longer work with paints. The business was required to upgrade controls and implement health surveillance.
Some substances require specific controls and health surveillance. Isocyanates (in many spray paints and coatings) are powerful respiratory sensitisers. Once sensitised, workers may never be able to work with those substances again. Prevention through proper COSHH assessment and controls is essential.
Source: Based on HSE prosecution records
Related sectors
COSHH applies across all industries, but some sectors face particular challenges:
Cleaners
COSHH guidance for cleaning businesses, including chemical safety and PPE requirements.
Painters & Decorators
Managing solvent exposure, spray painting, and respiratory protection requirements.
Manufacturing
Complex COSHH challenges including dusts, fumes, process chemicals, and exposure monitoring.
Healthcare
Managing disinfectants, drugs, biological agents, and sharps in healthcare settings.
Construction
Silica dust, cement, asbestos awareness, and respiratory protection on sites.
Hairdressers & Salons
Managing skin exposure to dyes, bleaches, and preventing occupational dermatitis.
Related content
What is a COSHH assessment?
Detailed guide to carrying out COSHH assessments, with examples and templates.
Understanding Safety Data Sheets
How to read and use Safety Data Sheets to inform your COSHH assessments.
Workplace Exposure Limits explained
What WELs are, how to use them, and when you need exposure monitoring.
Local Exhaust Ventilation (LEV) systems
When you need LEV, how it works, and your maintenance and testing duties.
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