The Control of Substances Hazardous to Health Regulations 2002 (COSHH) are the main legal framework protecting UK workers from health risks caused by exposure to hazardous substances in the workplace. COSHH applies across almost every industry — from hairdressing to construction, from cleaning to food production — and places a legal duty on employers and self-employed workers to assess and control the risks from substances hazardous to health.
According to HSE statistics, an estimated 12,000 lung disease deaths per year in Great Britain are linked to past exposures at work. COSHH exists to prevent those exposures before they cause harm.
What Is COSHH?
COSHH 2002 was made under the Health and Safety at Work etc. Act 1974 and implements in part the EU Chemical Agents Directive (98/24/EC). Post-Brexit the regulations remain in force in Great Britain. COSHH creates a hierarchy of control measures and requires employers to make a ‘suitable and sufficient’ assessment of the health risks from hazardous substances before work with those substances begins.
The key duty is in Regulation 7: “Every employer shall ensure that the exposure of his employees to substances hazardous to health is either prevented or, where this is not reasonably practicable, adequately controlled.”
What Substances Does COSHH Cover?
COSHH covers any substance, mixture or biological agent that is hazardous to health. This includes substances that are classified under the Classification, Labelling and Packaging (CLP) Regulation (EC No. 1272/2008) as: acutely toxic, skin corrosive, serious eye damage, carcinogenic, mutagenic, toxic to reproduction, or having specific target organ toxicity. It also covers all substances listed in EH40/2005 (the HSE’s Workplace Exposure Limits document), all dust above the general WEL thresholds, and biological agents encountered at work.
Common workplace substances that require COSHH assessment include: cleaning chemicals (bleach, descalers, disinfectants); hairdressing chemicals (peroxide, bleach, relaxers, tints); construction dusts (silica, wood, cement); welding fumes; isocyanates in paints and adhesives; solvents; pesticides and herbicides; and food dusts (flour, spices).
COSHH does not cover lead, asbestos or radioactive substances — these have their own specific regulations.
The COSHH Assessment: 5 Steps
Step 1 — Identify the hazardous substances
List all substances used or generated in your workplace. Check Safety Data Sheets (SDS) — suppliers are legally required to provide these for hazardous substances under REACH Regulation (EC No. 1907/2006). The SDS will tell you the hazard classification, WEL if applicable, and recommended control measures. Also identify substances generated by work processes — welding fumes, wood dust, silica from cutting stone or brick.
Step 2 — Assess who could be harmed and how
Identify which workers are exposed, how they are exposed (inhalation, skin contact, ingestion, injection), and for how long. Consider all routes of exposure — a substance absorbed through skin may pose as great a risk as one that is inhaled. Consider also maintenance workers, contractors, cleaners and others who may enter the area and be exposed indirectly.
Step 3 — Decide what precautions are needed
Apply the COSHH hierarchy of control in order: (1) eliminate the substance entirely; (2) substitute with a less hazardous alternative; (3) enclose the process; (4) use local exhaust ventilation (LEV); (5) reduce exposure time; (6) general ventilation; (7) personal protective equipment (PPE) as a last resort, not a substitute for other controls. PPE alone is not adequate control unless all other measures have been exhausted.
Step 4 — Record the assessment and implement controls
For employers with five or more employees, Regulation 6(4) requires the significant findings to be recorded. The record should identify the substance, the hazard, who is at risk, the control measures in place, and the results of any monitoring or health surveillance. This record forms part of your COSHH file and should be accessible to employees and HSE inspectors.
Step 5 — Review
COSHH assessments must be reviewed under Regulation 6(3) when there is reason to believe they are no longer valid — for example, when a new substance is introduced, when working methods change, when health surveillance results indicate a problem, or when a relevant WEL is revised in EH40. Best practice is to review annually regardless of changes.
COSHH by Industry
Cleaning
Cleaners regularly use bleach, disinfectants, descalers, floor strippers and solvent-based products. Common COSHH risks include respiratory sensitisation from spray products, skin dermatitis from prolonged contact, and chemical burns from concentrated acids and alkalis. Control measures must specify dilution ratios, ventilation requirements, PPE (nitrile gloves, eye protection) and safe storage to prevent mixing of incompatible chemicals (bleach and ammonia produce toxic chloramine gas).
Hairdressing and Beauty
Hairdressers face COSHH risks from hydrogen peroxide, persulphate-based bleaching agents, permanent colourants, and formaldehyde-releasing preservatives in some products. Occupational asthma caused by persulphate exposure is a recognised industrial disease. Control measures include adequate salon ventilation, latex-free gloves, and substitution of high-risk products where possible.
Catering and Food Production
Catering businesses use cleaning chemicals that require COSHH assessment. Food production environments may generate flour dust (a known respiratory sensitiser with a WEL of 1 mg/m³ over 8 hours under EH40) and spice dusts. Cleaning in place (CIP) chemicals used in food manufacturing include strong acids and caustic soda requiring full COSHH assessment and LEV.
Construction
Construction generates some of the most serious COSHH exposures in any industry. Respirable crystalline silica (RCS) from cutting stone, concrete, brick, mortar or tile has a WEL of 0.1 mg/m³ (8-hour TWA) under EH40. Silica causes silicosis — a fatal, irreversible lung disease. Welding fumes contain manganese, hexavalent chromium and other carcinogens. Wood dust from hardwoods is a Group 1 carcinogen (proven human carcinogen). All require specific COSHH assessment and engineered controls, not just PPE.
Health Surveillance
Regulation 11 of COSHH requires health surveillance where employees are exposed to substances linked to identified diseases or adverse health effects and there are valid techniques to detect them. Common triggers include: exposure to respiratory sensitisers (requiring lung function testing); skin exposure to known skin sensitisers (requiring dermatitis surveillance); and exposure above certain WELs for specific substances. Health surveillance records must be kept for at least 40 years under COSHH Regulation 11(5).
COSHH Penalties
Failure to comply with COSHH is a criminal offence under the Health and Safety at Work etc. Act 1974. The HSE can issue improvement notices, prohibition notices and prosecute. In the Magistrates Court the maximum fine is £20,000 per offence; in the Crown Court fines are unlimited. Directors and managers can be personally prosecuted and imprisoned for up to two years. The HSE’s Fee for Intervention (FFI) scheme charges £163 per hour for investigations into material breaches, adding significant financial exposure even without prosecution.
COSHH and Your Risk Assessment
A COSHH assessment is a specific type of risk assessment focused on hazardous substances. It sits within your broader health and safety risk assessment framework under MHSWR 1999 Regulation 3. Anyrisks generates fully written, UK-compliant COSHH risk assessments for your specific substances and workplace in under 2 minutes. See also: cleaning risk assessments, beauty salon risk assessments, and catering risk assessments.
