COSHH stands for the Control of Substances Hazardous to Health Regulations 2002. Four words, and each one narrows what the law actually covers: control (not ban), substances (including biological agents and dust), hazardous to health (a precise legal definition, not a general worry), and 2002 (the current version).
People usually search this term because someone at work said “that’s a COSHH issue” and they need to know what is meant. The short answer is above. The useful answer is that “hazardous to health” has a specific definition in law — and a lot of things people assume are COSHH are governed by entirely different regulations.
Breaking the acronym down
| Word | What it actually means |
|---|---|
| Control of | Not prohibition. The law accepts hazardous substances will be used, and requires exposure to be prevented where reasonably practicable — and adequately controlled where it isn’t. |
| Substances | Far wider than chemicals in bottles. Includes fumes, mists, vapours, gases, dust, biological agents and substances produced by a process. |
| Hazardous to Health | A defined legal term (Regulation 2), not a judgement call. Covers health effects only — not fire, explosion, pressure or temperature. |
| Regulations 2002 | Statutory Instrument 2002/2677, made under the Health and Safety at Work etc. Act 1974. It replaced earlier 1988, 1994 and 1999 versions and has been amended since. |
The common shorthand — “COSHH means chemicals” — is wrong in both directions. It is broader than chemicals, and narrower than “anything dangerous”.
What counts as “hazardous to health”?
Regulation 2 of COSHH 2002 defines a substance hazardous to health as one that falls into any of these:
- Substances classified as dangerous to health under the CLP Regulation — the ones carrying hazard pictograms and H-statements on the label
- Substances with a workplace exposure limit approved by the HSE and published in EH40
- Biological agents — bacteria, viruses, fungi and other micro-organisms connected with the work
- Dust of any kind, where not already covered above, at concentrations at or above 10 mg/m³ inhalable or 4 mg/m³ respirable, as an 8-hour time-weighted average
- Anything else creating a comparable health hazard — the catch-all that stops the list being gamed
Point 4 surprises people. Ordinary dust is a COSHH substance once there is enough of it, even if it carries no hazard label at all. Flour in a bakery, sawdust in a joinery, dust from cutting paving — all COSHH.
Point 5 matters too: a substance does not need a label to be caught. If it harms health in a comparable way, it is in scope.
What COSHH does NOT cover
This is where most confusion lives. Four significant hazards are excluded from COSHH because they have their own regulations:
| Not COSHH | Governed instead by |
|---|---|
| Asbestos | Control of Asbestos Regulations 2012 |
| Lead | Control of Lead at Work Regulations 2002 |
| Radioactive substances | Ionising Radiations Regulations |
| Fire and explosion risk from a substance | DSEAR (Dangerous Substances and Explosive Atmospheres Regulations) |
COSHH also does not cover hazards arising purely from a substance being at high pressure, or at extreme temperature — those are physical hazards, not health hazards in the COSHH sense.
The practical consequence: a solvent that is both toxic and highly flammable is subject to both COSHH (for the health risk) and DSEAR (for the fire and explosion risk). One assessment does not discharge the other duty.
For asbestos specifically, see asbestos awareness training — a completely separate regime with its own duty to manage.
Acronyms COSHH gets confused with
- CLP — Classification, Labelling and Packaging. The system that decides how substances are classified and what goes on the label. CLP tells you a substance is hazardous; COSHH tells you what to do about it at work. See COSHH symbols and hazard pictograms.
- CHIP — the older Chemicals (Hazard Information and Packaging for Supply) Regulations, now replaced by CLP. If a document references CHIP, it is out of date.
- REACH — Registration, Evaluation, Authorisation and Restriction of Chemicals. Governs manufacture and supply, not workplace use.
- SDS — Safety Data Sheet. The supplier’s document about a substance. An SDS is not a COSHH assessment. It describes the substance in general; a COSHH assessment considers how you use it, in what quantity, for how long, and who is exposed. Filing SDSs in a folder and calling it COSHH compliance is one of the most common failures inspectors find.
- WEL / EH40 — workplace exposure limits, the numbers COSHH controls against. See workplace exposure limits explained.
How is COSHH pronounced and written?
Pronounced “coss” — one syllable, rhyming with “loss”. Written in capitals as an acronym: COSHH, not Coshh or C.O.S.H.H.
Common misspellings you may be searching for: COSSH, COSH, CoSHH. The correct form has two Hs, for Hazardous to Health.
Note that “a COSHH” is often used loosely to mean a COSHH assessment — as in “have you done a COSHH for that?” That is workplace shorthand, not a legal term.
Who does COSHH apply to?
Every employer in Great Britain whose work involves substances hazardous to health — which is most of them. Offices with cleaning chemicals are in scope, not just factories and laboratories.
The duty sits with the employer, and it extends to protecting anyone who could be affected: employees, contractors, visitors and members of the public. Self-employed people have duties to themselves and others.
For what those duties actually are, see COSHH Regulations 2002: employer duties.
Where to start
If you have just been told something is “a COSHH issue”, the sequence is:
- Identify what the substance is and get the safety data sheet
- Work out how people are actually exposed — inhalation, skin contact, ingestion, injection
- Ask whether you can eliminate or substitute it entirely
- If not, control exposure, with PPE as the last resort rather than the first
- Record the assessment, train people, and check the controls keep working
That is a COSHH risk assessment, and the full picture is in our complete COSHH guide.
Further reading
COSHH training
Our COSHH Awareness course covers what counts as a substance hazardous to health, how exposure happens, the hierarchy of control, and what a COSHH assessment involves.
Related reading: What is COSHH? A complete guide · COSHH symbols explained · How to do a COSHH risk assessment
£9 per course. CPD accredited, 100 % online, verifiable e-certificate on completion. Pay for 2, get 3 — any 3 courses for £18.
Please note: this is a CPD-accredited awareness course and general information, not legal advice. It is not an Ofqual-regulated qualification. Always check your employer’s and scheme’s specific requirements.