What is COSHH?

COSHH Meaning & Definition

COSHH stands for the Control of Substances Hazardous to Health. It is a set of UK regulations that require employers to assess and control the risks from hazardous substances used, stored, or produced in the workplace.

The regulations are enforced by the Health and Safety Executive (HSE) and apply to every workplace in Great Britain where hazardous substances are present — from construction sites and hospitals to hair salons and school science labs.

Hazardous substances under COSHH include:

• Chemicals — solvents, adhesives, paints, acids, alkalis
• Products containing chemicals — cleaning agents, pesticides, cosmetics
• Fumes — welding fumes, soldering fumes, exhaust fumes
• Dusts — silica dust, wood dust, flour dust, cement dust
• Vapours — paint vapour, solvent vapour
• Mists — oil mist, cutting fluid mist
• Gases — carbon monoxide, chlorine, ammonia
• Biological agents — bacteria, viruses, fungi
• Nanotechnology materials

COSHH does not cover lead (which has its own regulations), asbestos (covered by the Control of Asbestos Regulations 2012), or radioactive substances.

The COSHH Regulations 2002

The Control of Substances Hazardous to Health Regulations 2002 (SI 2002/2677) are the current version of the COSHH regulations. They were made under the Health and Safety at Work etc. Act 1974 and replace the original 1988 COSHH regulations.

The regulations contain 21 regulations and 6 schedules covering:

• Regulation 6 — Assessment of health risks (the COSHH assessment)
• Regulation 7 — Prevention or control of exposure
• Regulation 8 — Use of control measures
• Regulation 9 — Maintenance, examination and testing of control measures (including LEV testing)
• Regulation 10 — Monitoring of exposure at the workplace
• Regulation 11 — Health surveillance
• Regulation 12 — Information, instruction and training

The accompanying Approved Code of Practice (ACOP) L5 provides practical guidance on how to comply with each regulation. While not law itself, following the ACOP is accepted as evidence of compliance.

Who Needs a COSHH Assessment?

Under UK law, every employer who uses, produces, or stores hazardous substances must carry out a suitable and sufficient COSHH assessment. This applies to self-employed people too, and covers a wide range of industries:

View COSHH guidance for all 15 industry sectors →

Key point: Even common cleaning products like bleach and multi-surface sprays require a COSHH assessment. If a substance has a GHS hazard symbol on the label, it needs assessing.

What is a COSHH Assessment?

A COSHH assessment (also called a COSHH risk assessment) is a documented evaluation of the health risks from hazardous substances in your workplace. It is a legal requirement under Regulation 6 of the COSHH Regulations 2002.

A proper COSHH assessment must:

• Identify every hazardous substance present in the workplace
• Consider all routes of exposure — inhalation, skin absorption, ingestion, and injection
• Assess who is at risk and how severely
• Document the control measures in place and any additional measures needed
• Set out emergency procedures, health surveillance requirements, and monitoring
• Be reviewed regularly — at least annually or when circumstances change

Unlike a general risk assessment, a COSHH assessment is substance-specific. Each hazardous substance (or group of similar substances used in the same way) needs its own assessment that references the Safety Data Sheet (SDS).

GHS Hazard Symbols Explained

The Globally Harmonized System (GHS) uses 9 standard hazard pictograms on chemical labels and Safety Data Sheets. These red diamond-shaped symbols quickly communicate the type of danger. Understanding them is essential for COSHH assessments.

Workplace Exposure Limits (WELs) & EH40

Workplace Exposure Limits (WELs) are the maximum concentrations of airborne substances to which workers may be legally exposed. They are published in EH40/2005 (with amendments) by the HSE.

There are two types of WEL:

• 8-hour TWA (Time-Weighted Average) — the maximum average concentration over an 8-hour working day
• STEL (Short-Term Exposure Limit) — the maximum average concentration over a 15-minute reference period

Key WEL Examples

Employers must ensure exposure does not exceed the WEL, and where reasonably practicable, reduce exposure well below the WEL. COSHH.app automatically includes relevant WELs in generated reports.

Safety Data Sheets (SDS)

A Safety Data Sheet (SDS) — formerly known as a Material Safety Data Sheet (MSDS) — is a detailed document provided by the chemical manufacturer or supplier. Under UK REACH regulations, suppliers must provide an SDS for any hazardous substance.

An SDS contains 16 mandatory sections:

1. Identification of the substance/mixture
2. Hazards identification
3. Composition/information on ingredients
4. First-aid measures
5. Firefighting measures
6. Accidental release measures
7. Handling and storage
8. Exposure controls / Personal protection (includes WELs and PPE)
9. Physical and chemical properties
10. Stability and reactivity
11. Toxicological information
12. Ecological information
13. Disposal considerations
14. Transport information
15. Regulatory information
16. Other information

Sections 4, 7, and 8 (highlighted in bold) are the most critical for COSHH assessments. COSHH.app automatically retrieves SDS data when you scan a chemical label, saving you hours of manual searching.

COSHH Health Surveillance

Regulation 11 of COSHH requires health surveillance where workers are exposed to substances linked to identifiable diseases or adverse health effects. It must be carried out by a competent person (often an occupational health professional).

Health surveillance is required when workers are regularly exposed to:

• Isocyanates — lung function tests (used in spray painting, foam manufacturing)
• Silica dust — lung function tests and chest X-rays (construction, quarrying)
• Hardwood dust — nasal examination (carpentry, furniture making)
• Solvents — biological monitoring and skin checks
• Chromium compounds — skin and lung checks (chrome plating)
• Latex — skin and respiratory checks (healthcare)
• Flour dust — lung function tests (bakeries)

Employers must keep health surveillance records for at least 40 years from the date of the last entry. Read our detailed guide to COSHH health surveillance.

LEV Testing & COSHH Regulation 9

Local Exhaust Ventilation (LEV) is one of the most important engineering controls for managing airborne hazardous substances. COSHH Regulation 9 requires that all engineering controls, including LEV systems, are:

• Maintained in efficient working order
• Thoroughly examined and tested at least every 14 months (or 6 months for certain processes like blasting)
• Records kept for at least 5 years

LEV testing must be carried out by a competent person who has the necessary training, knowledge, and experience. The HSE's guidance document HSG258 provides detailed advice on LEV maintenance and testing.

Read our full guide: LEV Testing: What UK Employers Need to Know →

Penalties for Non-Compliance

Non-compliance with COSHH is a criminal offence. The HSE actively investigates and prosecutes businesses that fail to protect workers from hazardous substances.

Real UK Prosecution Examples

• £3.8 million fine — A chemical company prosecuted after two employees suffered serious chemical burns from caustic soda due to inadequate controls
• £340,000 fine — A manufacturing company fined after a worker was seriously injured while cleaning machinery without adequate protective measures
• £100,000 fine — A Bristol company fined for failing to prevent allergic contact dermatitis from chemical exposure
• Personal imprisonment — Directors and managers can face prison for serious breaches where they consented to or were complicit in the offence

Stay informed about the latest HSE enforcement actions on our COSHH compliance blog.

The Business Case for COSHH Compliance

• Reduced sick days — proper controls reduce absence from chemical-related illness
• Improved staff morale — employees value employers who take safety seriously
• Lower insurance premiums — strong compliance records reduce liability insurance costs
• Client confidence — many supply chains require evidence of COSHH compliance as a contract condition
• Legal protection — documented assessments provide evidence of due diligence if an incident occurs

COSHH Training Requirements

Regulation 12 requires employers to provide adequate information, instruction, and training to employees who may be exposed to hazardous substances. Training must cover:

• The nature of the substances they work with and their risks
• How to use control measures and PPE correctly
• Emergency procedures for spills and accidental exposure
• Results of any workplace exposure monitoring
• Health surveillance procedures and the importance of attending appointments

Training should be provided when an employee first starts work, when they change roles, when new substances are introduced, and as regular refreshers. COSHH.app Premium plans include built-in staff training modules with digital sign-off tracking.

COSHH Software & Digital Assessments

The HSE fully accepts digital COSHH assessments. Modern COSHH software eliminates the paperwork burden while ensuring compliance. COSHH.app is a UK-built COSHH risk assessment platform designed specifically for British workplaces.

How COSHH.app Works

1. Scan the chemical label — use your phone camera to photograph the label. AI reads the GHS symbols, hazard statements, CAS number, and manufacturer details.
2. Automatic SDS retrieval — COSHH.app retrieves the relevant Safety Data Sheet data including WELs, PPE requirements, and first aid measures.
3. Generate COSHH report — select your chemicals, workplace, and task description. AI generates a comprehensive, inspection-ready COSHH risk assessment in minutes.
4. Download as PDF — professional PDF reports ready for HSE inspectors, audits, and client submissions.

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