COSHH stands for Control of Substances Hazardous to Health. The COSHH Regulations 2002 require employers to control exposure to hazardous substances to protect workers and others who may be exposed. This includes chemicals, dust, fumes, vapours, mists, and biological agents.
Do you work with hazardous substances?
Let's point you to the right information.
What is COSHH?
COSHH stands for Control of Substances Hazardous to Health. It's a set of regulations that came into force in 2002 (and have been updated several times since) to protect workers from the health risks of hazardous substances.
The COSHH Regulations 2002 require employers to:
- Assess the risks from hazardous substances
- Control exposure to prevent ill health
- Maintain control measures and equipment
- Monitor exposure where necessary
- Carry out health surveillance where appropriate
- Prepare plans for dealing with accidents and emergencies
- Provide information, instruction and training for employees
- Keep records of assessments, monitoring, and health surveillance
COSHH is about preventing illness caused by hazardous substances at work. This includes immediate harm (like chemical burns) and long-term effects (like occupational asthma, cancer, or dermatitis).
What substances are covered by COSHH?
The COSHH Regulations apply to almost all hazardous substances used or created at work, including:
Chemicals and products
- Cleaning chemicals (bleach, disinfectants, degreasers)
- Paints, varnishes, adhesives, and solvents
- Pesticides and herbicides
- Acids and alkalis
- Gases (chlorine, carbon monoxide, LPG)
- Laboratory reagents
- Manufacturing chemicals
Dust and particulates
- Wood dust (especially hardwood)
- Silica dust from stone, concrete, brick
- Metal dusts and fumes
- Flour dust (baker's asthma)
- Cement dust
- Grain dust
Fumes and vapours
- Welding and soldering fumes
- Vehicle exhaust fumes
- Fumes from hot processes
- Vapours from solvents and chemicals
Biological agents
- Bacteria, viruses, fungi
- Blood and body fluids
- Sewage and waste materials
- Compost and soil organisms
- Animal materials and droppings
COSHH does NOT cover asbestos (separate regulations), lead (separate regulations), radioactive substances (separate regulations), or hazards from substances like high temperature or pressure (covered by other health and safety law).
How do I know if a substance is hazardous?
Check for hazard symbols and warning labels on containers:
Common hazard pictograms:
- Skull and crossbones — Toxic or fatal if swallowed, inhaled, or absorbed through skin
- Exclamation mark — Harmful or irritant, can cause skin/eye irritation or allergies
- Corrosion — Corrosive to metals and can cause severe skin burns and eye damage
- Flame — Flammable liquids, gases, or aerosols
- Health hazard — May cause or worsen respiratory problems, allergies, cancer, or reproductive harm
- Environmental hazard — Toxic to aquatic life and the environment
Every hazardous substance must have a Safety Data Sheet (SDS), which provides detailed information about:
- What the substance is and what it contains
- Hazards it presents
- How to use it safely
- First aid measures
- Safe storage and disposal
- Emergency procedures
Always request Safety Data Sheets from your suppliers when purchasing chemicals or hazardous products. Keep them accessible where the substances are used.
The 8 steps of COSHH compliance
The Health and Safety Executive recommends eight steps to comply with COSHH:
Step 1: Assess the risks
Identify:
- What hazardous substances are present
- Who might be exposed and how
- What harm they could cause
- How likely exposure is to occur
- Whether existing precautions are adequate
You must record your COSHH assessment if you have 5 or more employees (though it's good practice for everyone).
Step 2: Decide what precautions are needed
Follow the hierarchy of control measures:
- Elimination — Can you stop using the substance entirely?
- Substitution — Can you use a safer alternative?
- Engineering controls — Enclose the process, use local exhaust ventilation (LEV), automate
- Administrative controls — Reduce exposure time, rotate workers, provide training
- Personal Protective Equipment (PPE) — Gloves, respirators, goggles (last resort, not first)
PPE is the last line of defence, not the first. You must try to eliminate or reduce the risk at source before relying on PPE.
Step 3: Prevent or adequately control exposure
Implement your chosen control measures. "Adequate control" means:
- Exposure is below any Workplace Exposure Limit (WEL)
- You're applying the principles of good practice for control
- If it's a carcinogen, mutagen, or respiratory sensitiser, you're reducing exposure to as low as reasonably practicable
Step 4: Ensure control measures are used and maintained
- Make sure control equipment (like ventilation systems) is working properly
- Check equipment regularly and service it according to schedule
- Keep maintenance records
- Ensure employees use controls correctly
Statutory examination requirements:
- Local exhaust ventilation (LEV) — thorough examination at least every 14 months
- Respiratory protective equipment (RPE) — examined at suitable intervals (monthly for breathing apparatus)
Step 5: Monitor exposure
For some substances, you must measure workers' exposure to ensure it stays below Workplace Exposure Limits. This is particularly important if:
- You're working close to the exposure limit
- Control measures might fail
- Exposure levels vary significantly
Monitoring should be carried out by a competent person (often an occupational hygienist) and records kept for at least 5 years (40 years for carcinogens).
Step 6: Carry out health surveillance
If exposure to a hazardous substance could cause an identifiable disease or health effect, you must provide health surveillance. This includes:
- Skin checks for substances causing dermatitis
- Lung function tests for respiratory sensitisers (isocyanates, flour dust)
- Medical questionnaires for early detection of symptoms
- Biological monitoring for some substances (e.g., lead in blood)
Health surveillance must be carried out by a qualified person (occupational health professional) and records kept for at least 40 years for certain substances.
Engineering firm fined £200,000 for welding fume exposure
A metalworking company employed several welders who worked without adequate fume extraction. Over time, multiple employees developed occupational asthma and respiratory problems.
- ✗No COSHH assessment for welding fumes
- ✗Inadequate local exhaust ventilation
- ✗No exposure monitoring
- ✗No health surveillance for welders
- ✗Employees not provided with RPE
- ✗No training on fume hazards
Following HSE investigation, the company was prosecuted and fined £200,000 plus costs. Several employees suffered permanent respiratory damage and could no longer work as welders.
Welding fumes are a known respiratory hazard. Proper extraction, monitoring, and health surveillance are essential. The long-term health costs and legal penalties far exceed the cost of proper controls.
Step 7: Prepare plans and procedures for accidents and emergencies
Have arrangements in place to deal with:
- Spills and leaks
- Equipment failure
- Unexpected high exposure
- Fire involving hazardous substances
Your emergency plan should include:
- How to raise the alarm
- Evacuation procedures
- Location of emergency equipment (spill kits, eyewash stations, safety showers)
- First aid arrangements
- Who to contact (emergency services, suppliers)
Step 8: Provide information, instruction and training
Employees must be informed about:
- The hazardous substances they work with
- The health risks
- Control measures and how to use them
- Results of monitoring and health surveillance (anonymised)
- What to do in an emergency
Training should be:
- Provided before working with hazardous substances
- Refreshed regularly
- Recorded (who, when, what was covered)
- Practical and relevant to the actual work being done
COSHH Compliance Schedule
Visual check that extraction, PPE, and procedures are being followed
Check substances are stored safely, labels intact, no leaks
Learn from incidents and update procedures if needed
Statutory examination of local exhaust ventilation by competent person
Check assessments are still valid, update if anything has changed
Update employee knowledge and check competence
Workplace Exposure Limits (WELs)
Workplace Exposure Limits are the maximum concentrations of hazardous substances in air that workers can be exposed to. They're measured over two time periods:
- Long-term exposure limit (8-hour TWA) — The average concentration over an 8-hour working day
- Short-term exposure limit (15-minute reference period) — The average concentration over any 15-minute period
WELs are published by the HSE in EH40: Workplace Exposure Limits. If a substance has a WEL, you must ensure exposure does not exceed it. This usually requires:
- Effective control measures
- Air monitoring to measure actual exposure
- Record keeping
Even if exposure is below the WEL, you must still reduce exposure as much as reasonably practicable for substances that cause cancer, asthma, genetic damage, or reproductive harm.
Safety Data Sheets (SDS)
Every hazardous chemical product must come with a Safety Data Sheet (formerly called Material Safety Data Sheet or MSDS). The SDS follows a standard 16-section format:
- Identification of the substance and supplier
- Hazards identification
- Composition/information on ingredients
- First aid measures
- Fire-fighting measures
- Accidental release measures
- Handling and storage
- Exposure controls/personal protection
- Physical and chemical properties
- Stability and reactivity
- Toxicological information
- Ecological information
- Disposal considerations
- Transport information
- Regulatory information
- Other information
Section 8 is particularly important for COSHH assessments — it tells you what exposure limits apply and what control measures and PPE are recommended.
Create a central SDS library (physical folder or digital system) so employees can easily access safety information. Review SDSs regularly — suppliers update them when new hazard information becomes available.
Common workplace hazardous substances
You might be surprised how many everyday workplace activities involve hazardous substances:
Industry-Specific COSHH Hazards
Offices & Retail
- •Cleaning chemicals (bleach, disinfectants)
- •Printer/copier toner dust
- •Correction fluids and markers
- •Pest control chemicals
- •Air fresheners and sanitisers
Manufacturing & Construction
- •Welding and soldering fumes
- •Wood and metal dusts
- •Paints, solvents, and adhesives
- •Cement and concrete dust
- •Silica dust from cutting stone/concrete
- •Engine exhaust fumes
Bottom line: Every workplace has some exposure to hazardous substances. The level of control needed depends on the substance, the amount used, and how it's used.
Healthcare and social care
- Disinfectants and sterilising agents
- Latex (allergen in gloves)
- Cytotoxic drugs
- Biological hazards (blood, bodily fluids, pathogens)
- Cleaning chemicals
Agriculture
- Pesticides and herbicides
- Fertilisers
- Veterinary medicines
- Animal waste and urine (biological hazards)
- Grain and hay dust
- Zoonotic diseases (diseases from animals)
Laboratories
- Chemical reagents (acids, alkalis, solvents)
- Biological cultures
- Carcinogens and mutagens
- Compressed gases
- Radioactive materials (separate regulations)
Hairdressing and beauty
- Hair dyes and bleaches
- Permanent wave solutions
- Nail products (acrylics, acetone)
- Aerosol sprays
- Skin sensitisers (can cause dermatitis)
Hairdressers have some of the highest rates of occupational dermatitis and asthma in the UK. Proper glove use, ventilation, and technique can significantly reduce these risks.
Who is responsible for COSHH compliance?
Employers are responsible for:
- Carrying out COSHH assessments
- Providing and maintaining control measures
- Providing information, instruction, and training
- Monitoring exposure and health surveillance
- Keeping records
Employees must:
- Use control measures and PPE provided
- Report defects in control measures
- Follow safe working procedures
- Attend training
Self-employed people have the same duties as employers for protecting themselves and others affected by their work.
COSHH assessment template
A good COSHH assessment includes:
Substance information:
- Product name and supplier
- Where it's used and for what purpose
- Quantity and frequency of use
- Physical form (liquid, dust, gas, etc.)
Hazard identification:
- What hazards does it present (from SDS and labels)
- What route of exposure (inhalation, skin contact, ingestion, eye contact)
- What health effects could it cause (immediate and long-term)
People at risk:
- Who is exposed (job roles)
- Are any particularly vulnerable (young, pregnant, sensitised)
Existing control measures:
- What controls are currently in place
- Are they adequate and working properly
Risk evaluation:
- Is exposure prevented or adequately controlled?
- Is exposure below any WEL?
- Are principles of good practice being followed?
Action plan:
- What improvements are needed
- Who is responsible
- Target date for completion
Review date:
- When the assessment should be reviewed
When to review your COSHH assessment
Review your COSHH assessments:
- At least every 2-3 years (good practice)
- When anything significant changes:
- New substances introduced
- Different work methods
- New information about health risks
- Changes to control measures
- Increase in quantity used or frequency
- After an incident involving the substance
- If monitoring or health surveillance indicates controls aren't working
- If you think it's no longer valid
If you introduce a new hazardous substance, you must complete a COSHH assessment BEFORE starting to use it. Don't wait for the annual review cycle.
COSHH and pregnancy
Some substances are particularly hazardous to pregnant women and unborn babies:
- Biological agents (rubella, chickenpox, toxoplasmosis)
- Lead and other heavy metals
- Pesticides and herbicides
- Solvents and certain chemicals
- Cytotoxic drugs
If a risk assessment identifies risks to new or expectant mothers, you must:
- Alter the working conditions or hours to avoid the risk
- If that's not reasonable, offer suitable alternative work
- If alternative work isn't available, suspend the employee on full pay
You should have a general policy covering new and expectant mothers, not wait until someone announces their pregnancy.
Frequently asked questions
A COSHH assessment is a specific type of risk assessment that focuses on hazardous substances. A general risk assessment covers all workplace hazards (slips, trips, machinery, etc.), while COSHH specifically addresses health risks from substances.
Not necessarily. If you use several similar products in the same way (e.g., different brands of cleaning spray), you can often cover them in one assessment. However, products with different hazards or used differently need separate assessment.
COSHH assessments and training records: at least 5 years. Exposure monitoring records: at least 5 years. Health surveillance records: at least 40 years for certain substances (carcinogens, mutagens, asthmagens). Check specific requirements for the substances you use.
No. PPE is the last line of defence in the hierarchy of controls. You must first try to eliminate the hazard, substitute for something safer, or use engineering controls like ventilation. Only use PPE as an additional measure or when other controls aren't practicable.
Under REACH and CLP regulations, suppliers must provide an SDS for hazardous substances. If they refuse, it's a breach of regulations. Consider finding a different supplier. You cannot safely use a hazardous substance without knowing what's in it and how to control the risks.
Yes, if they're hazardous. Many common cleaning chemicals are corrosive, irritant, or harmful. Even 'everyday' products like bleach, oven cleaner, and toilet cleaner require assessment. The assessment might be brief for low-risk use, but it's still required.
Someone with sufficient training, experience, and knowledge to identify hazards and evaluate risks. For simple substances (common cleaning products), a trained manager may be competent. For complex exposures (welding fumes, solvents, biological agents), you may need an occupational hygienist.
The HSE can issue improvement notices or prohibition notices. Prosecution can lead to unlimited fines in the Crown Court and up to 2 years imprisonment for serious breaches. Companies have been fined hundreds of thousands of pounds for COSHH failures that caused ill health.
Next steps
To check whether you need COSHH assessments, use our substance checker tool:
To download a COSHH assessment template and guidance:
Not sure if your COSHH controls are adequate? An occupational hygienist can assess your workplace, measure exposure levels, and recommend improvements to protect your employees' health.
Related articles:
- COSHH Assessment Requirements
- Understanding Workplace Exposure Limits
- Safe Storage of Hazardous Substances
Useful tools: