Guide
Comply with COSHH regulations for hazardous substances
How to comply with the Control of Substances Hazardous to Health Regulations 2002. Step-by-step guide to COSHH assessment, the hierarchy of controls, Workplace Exposure Limits, health surveillance requirements and record keeping.
What COSHH requires you to do
The Control of Substances Hazardous to Health Regulations 2002 (COSHH) require employers to prevent or adequately control employee exposure to hazardous substances in the workplace.
COSHH applies to most businesses, not just those in obviously hazardous industries. If your employees use cleaning products, paints, adhesives, solvents, or work in environments with dust, fumes or biological agents, COSHH applies to you.
This guide explains your legal duties, how to conduct a COSHH assessment, and how to implement effective controls.
When COSHH applies to your business
COSHH covers substances that can cause harm to health, including:
- Chemicals: Cleaning products, solvents, paints, adhesives, pesticides, disinfectants
- Dusts: Wood dust, flour dust, silica dust, metal dusts
- Fumes: Welding fumes, soldering fumes, exhaust fumes
- Vapours: From solvents, fuels, or heated processes
- Mists: Oil mists, paint sprays, coolant mists
- Gases: Carbon monoxide, chlorine, ammonia
- Biological agents: Bacteria, viruses, fungi (e.g. Legionella, bloodborne pathogens)
- Nanotechnology materials: Engineered nanoparticles
COSHH does NOT cover:
- Asbestos (separate Control of Asbestos Regulations 2012)
- Lead (Control of Lead at Work Regulations 2002)
- Radioactive materials (Ionising Radiations Regulations 2017)
These substances have their own specific regulations with additional requirements.
Your 8 COSHH duties as an employer
COSHH Regulation 6-13 sets out 8 specific duties that apply to all employers:
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1. Assess the risks (Regulation 6)
Conduct a COSHH assessment for every hazardous substance your employees may be exposed to. This must be done BEFORE work with the substance begins. The assessment must be suitable and sufficient.
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2. Prevent or control exposure (Regulation 7)
Prevent exposure to hazardous substances, or where this is not reasonably practicable, adequately control exposure. Use the hierarchy of controls (ERICPD) to determine appropriate measures.
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3. Use control measures properly (Regulation 8)
Ensure any control measures (ventilation, enclosures, PPE) are used properly. Employees must use controls as instructed - this is also an employee duty under Regulation 8(2).
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4. Maintain, examine and test controls (Regulation 9)
Keep control measures in efficient working order and good repair. Local exhaust ventilation (LEV) must be thoroughly examined and tested at least every 14 months (or as specified in Schedule 4).
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5. Monitor exposure (Regulation 10)
Carry out workplace exposure monitoring where required - for example, if you cannot demonstrate by other means that exposure limits are being met, or if controls might fail.
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6. Carry out health surveillance (Regulation 11)
Provide appropriate health surveillance where the risk assessment identifies employees exposed to substances linked to identifiable diseases or adverse health effects, and there is a reasonable likelihood of exposure.
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7. Provide information, instruction and training (Regulation 12)
Give employees comprehensible information about the hazards, risks and control measures. Provide training on safe handling, what to do if something goes wrong, and results of any exposure monitoring.
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8. Deal with accidents, incidents and emergencies (Regulation 13)
Have procedures in place to deal with accidents, incidents and emergencies involving hazardous substances. This includes spill procedures, first aid arrangements, and reporting under RIDDOR where applicable.
The hierarchy of controls (ERICPD)
COSHH requires you to apply controls in a specific order of priority. You must always consider measures higher up the hierarchy before moving to lower levels:
- E - Eliminate
- Remove the hazardous substance entirely - use a non-hazardous alternative process or stop the activity
- R - Reduce (Substitute)
- Replace with a less hazardous substance - use water-based instead of solvent-based products
- I - Isolate
- Enclose the process so workers are separated from the hazard - use fume cupboards, glove boxes
- C - Control (Engineering)
- Use local exhaust ventilation (LEV), general ventilation, or other engineering controls to reduce exposure
- P - PPE (Personal Protective Equipment)
- Respirators, gloves, goggles - use ONLY as a last resort or combined with other measures
- D - Discipline (Administrative)
- Safe systems of work, procedures, training, supervision, signage, reduced exposure time
Critical principle: PPE should never be your first choice. It is the last line of defence, not the first. If you rely solely on PPE, HSE will question whether you have adequately considered higher-level controls.
In practice, most effective COSHH control involves a combination of measures - for example, substituting a less hazardous substance, using LEV, AND providing PPE for additional protection.
Workplace Exposure Limits (WELs) and EH40
Workplace Exposure Limits are the maximum concentrations of hazardous substances that can be present in workplace air, averaged over a reference period. They are legally binding limits that must not be exceeded.
WELs are published in HSE document EH40, which lists over 500 substances. You must check EH40 for any substance your employees are exposed to.
- Long-term exposure limit (LTEL)
- 8-hour time-weighted average (TWA) - the maximum average concentration over a normal 8-hour working day
- Short-term exposure limit (STEL)
- 15-minute reference period - the maximum concentration over any 15-minute period (for substances with acute effects)
- Where to find WELs
- HSE publication EH40 'Workplace Exposure Limits' - updated annually
- Legal status
- Exceeding a WEL is a breach of COSHH Regulation 7 - employers must ensure exposure does not exceed these limits
Important: WELs are maximum permitted concentrations, not safe levels. You must reduce exposure as low as is reasonably practicable, even if below the WEL. Some substances (carcinogens, mutagens, asthmagens) have no truly safe level - any exposure carries risk.
For substances without a WEL, you must still control exposure to a level that protects health, using industry guidance and good practice.
Health surveillance requirements
Health surveillance is the medical monitoring of employees to detect early signs of work-related ill health. Under COSHH Regulation 11, you must provide health surveillance where:
- Employees are exposed to substances linked to identifiable diseases or adverse health effects
- There is a reasonable likelihood that the disease or effect will occur under the conditions of work
- There are valid techniques to detect the disease or effect
Health surveillance record keeping
COSHH imposes strict record retention requirements for health surveillance:
- Individual health records
- Must be kept for at least 40 years from the date of the last entry
- What records must show
- Name, date of birth, employment history, dates and conclusions of health surveillance procedures
- Exposure monitoring records (where individuals identified)
- 40 years from the date of last entry
- Exposure monitoring records (individuals not identified)
- 5 years from the date of last entry
- If business ceases trading
- Records must be offered to HSE
Why 40 years? Some occupational diseases (e.g. mesothelioma, occupational cancers) have latency periods of 20-50 years. Records may be needed decades later to establish exposure history for compensation claims or epidemiological studies.
Information, instruction and training
Regulation 12 requires you to provide employees with suitable and sufficient information, instruction and training about:
- The nature of the hazardous substances they work with and their health effects
- The risks created by exposure and factors affecting risk (duration, concentration, route)
- The control measures in place and why they matter
- How to use controls properly - including PPE, LEV, safe handling procedures
- Results of exposure monitoring - where relevant to their work
- Results of health surveillance (with appropriate confidentiality)
- Emergency procedures - what to do if there is a spill, leak or exposure incident
Training must be provided:
- Before employees start working with hazardous substances
- When work processes change
- When new substances are introduced
- At regular intervals as refresher training
Safety data sheets (SDS): Your suppliers must provide SDS for hazardous substances. These are essential for COSHH assessments and must be accessible to employees who need them.
COSHH assessment process - step by step
A COSHH assessment must be suitable and sufficient. Here is how to conduct one:
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Step 1: Identify hazardous substances
List all substances used, produced or encountered in your workplace. Include raw materials, products, by-products, waste, cleaning materials, and substances that may be released during work (e.g. dust from cutting). Do not forget biological agents.
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Step 2: Gather information
Obtain safety data sheets (SDS) from suppliers. Check EH40 for WELs. Review HSE guidance for your industry. Look at the hazard classification on labels (GHS pictograms and hazard statements).
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Step 3: Evaluate the risks
Consider who might be exposed, how often, for how long, and by what route (inhalation, skin contact, ingestion). Consider the hazard severity and the likelihood of harm occurring.
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Step 4: Decide on control measures
Apply the hierarchy of controls (ERICPD). Can you eliminate or substitute? If not, what engineering controls, administrative controls and PPE are needed? Document your decisions and reasoning.
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Step 5: Record your assessment
The assessment must be recorded. Include substance identity, hazards, who is at risk, existing controls, additional measures needed, and review date. HSE recommends using their COSHH assessment form as a template.
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Step 6: Implement controls
Put the control measures in place before work begins. Ensure employees are trained. Provide any required PPE.
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Step 7: Monitor and review
Check controls are working. Carry out exposure monitoring if needed. Review the assessment whenever there is reason to suspect it is no longer valid - e.g. after an incident, change in process, or new health information.
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Step 8: Consult employees
Involve employees in the assessment process. They often know practical details about how substances are actually used. Consult safety representatives where appointed.
COSHH Essentials - HSE's free tool
HSE provides a free online tool called COSHH Essentials that helps small businesses identify appropriate control measures. You answer questions about the substance (hazard classification) and the task (amount used, dustiness/volatility), and the tool recommends control approaches.
COSHH Essentials is a good starting point for common substances and straightforward tasks. For complex situations, unusual substances, or where WELs are involved, you may need more detailed assessment.
Common COSHH compliance failures
HSE inspectors frequently identify these failings:
- No COSHH assessment - or assessments that are generic, out of date, or not task-specific
- Over-reliance on PPE - using respirators when LEV would be more effective
- LEV not maintained or tested - extraction systems that do not work properly
- No exposure monitoring - when assessment cannot demonstrate controls are adequate
- Inadequate training - employees do not understand the risks or how to use controls
- Poor housekeeping - contaminated surfaces, inadequate cleaning, dust accumulation
- No health surveillance - when required by the nature of exposure
- Records not kept - missing or incomplete documentation
What to do next
If you have not already done so:
- Make an inventory of all hazardous substances in your workplace
- Gather safety data sheets from your suppliers
- Conduct COSHH assessments for each substance and task
- Implement controls using the hierarchy (ERICPD)
- Train your employees on the hazards and controls
- Set up health surveillance if required
- Review regularly and keep records
For help with COSHH assessments, use HSE's COSHH Essentials tool or consult a competent health and safety adviser.