If you store or use chemicals at work, you'll have seen the orange-and-white or red-and-white diamond symbols on the labels. These are the COSHH hazard symbols — the quickest way to tell, at a glance, what a substance can do and how it needs to be stored and handled. This guide explains all nine current symbols, what each one means, how the old and new symbols differ, and how they link to your storage and COSHH duties.
What are COSHH symbols?
COSHH stands for the Control of Substances Hazardous to Health Regulations 2002 — the UK law that requires employers to control exposure to hazardous substances. The symbols themselves aren't actually defined by COSHH; they come from the CLP Regulation (Classification, Labelling and Packaging), which is the UK's version of the global GHS system. In everyday use, though, almost everyone calls them "COSHH symbols" because they're the signs that tell you a substance falls under your COSHH controls.
Each symbol is a red-bordered white diamond with a black pictogram inside. They appear on supplier labels and safety data sheets, and they're the starting point for your COSHH risk assessment: the symbol tells you the type of hazard, and the data sheet tells you what to do about it.
The 9 COSHH hazard symbols and their meanings
1. Explosive
Symbol: an exploding bomb. Warns of substances that can explode, including organic peroxides and self-reactive materials. Keep away from heat, shock, friction and ignition sources.
2. Flammable
Symbol: a flame. Covers flammable gases, aerosols, liquids and solids — solvents, fuels, thinners and many cleaning products. Store away from ignition sources and in suitable flammable or COSHH cabinets, and control vapours.
3. Oxidising
Symbol: a flame over a circle (an "O" on fire). Marks oxidisers that can intensify a fire or cause one even without an obvious ignition source. Keep well separated from flammables and combustible materials.
4. Gas under pressure
Symbol: a gas cylinder. Identifies compressed, liquefied or refrigerated gases. The hazard is both the contents and the pressure — cylinders can rupture or rocket if damaged. Store upright, secured and ventilated, ideally in a dedicated gas cylinder cage or store.
5. Corrosive
Symbol: liquid dripping onto a hand and a surface. Warns of substances that destroy living tissue or corrode metal — strong acids and alkalis among them. Requires appropriate PPE, segregation and often dedicated acid or chemical storage.
6. Acute toxicity
Symbol: a skull and crossbones. The most serious health symbol: substances that are toxic or fatal in small amounts by swallowing, skin contact or inhalation. Strict controls, secure storage and clear procedures are essential.
7. Health hazard / hazardous to health
Symbol: an exclamation mark. Indicates substances that can cause less severe effects — skin or eye irritation, allergic skin reaction, drowsiness or dizziness. Often seen on everyday workplace chemicals; still requires control under COSHH.
8. Serious health hazard
Symbol: a starburst on a human chest/torso. Flags the most serious longer-term health effects: carcinogens, mutagens, substances toxic to reproduction, respiratory sensitisers and those that damage organs. These demand the tightest exposure controls.
9. Hazardous to the environment
Symbol: a dead tree and fish. Marks substances that are toxic to aquatic life or the wider environment. Storage and spill control matter here — secondary containment and bunding stop a leak reaching drains and watercourses.
Old COSHH symbols vs new symbols
If your site has older stock or signage, you may still see the old orange-and-black square symbols. These were phased out under CLP and fully replaced by the current red-and-white diamonds in 2017. The hazards they describe are broadly the same, but a few changed: the old "harmful/irritant" orange cross (St Andrew's cross) was split into the new exclamation-mark and serious-health-hazard symbols, and the gas-cylinder symbol was added. If you find old orange symbols on labels still in use, treat the substance as hazardous and check the current safety data sheet, because the labelling should have been updated.
What the symbols mean for storage and COSHH compliance
The symbols aren't just information — they drive how a substance must be stored, segregated and controlled. A few practical points:
- Segregate incompatible hazards. Oxidisers away from flammables, acids away from alkalis. The symbols are your first clue to what must not be stored together.
- Match the storage to the hazard. Flammables and many toxic or corrosive substances belong in a purpose-built cabinet. Our hazardous storage range includes COSHH cabinets, flammable and acid cabinets, each designed with a leak-retaining sump.
- Contain spills. The corrosive and environmental symbols point to the need for bunding and spill containment so a leak can't reach people, drains or watercourses.
- Record it in your assessment. Under COSHH you must assess the risk, control exposure, label and store correctly, and train staff to recognise the symbols.
For the legal detail on cabinets and segregation, see our guide to COSHH cabinet requirements, which explains what UK law expects of your hazardous-substance storage.
COSHH symbols FAQ
What are the 9 symbols of COSHH?
Explosive, flammable, oxidising, gas under pressure, corrosive, acute toxicity (skull and crossbones), health hazard (exclamation mark), serious health hazard, and hazardous to the environment. Each is a black pictogram in a red-bordered white diamond.
Are COSHH symbols the same as CLP or GHS symbols?
Yes — the symbols people call "COSHH symbols" are the CLP hazard pictograms, the UK's implementation of the international GHS system. COSHH is the regulation that requires you to control the substances; CLP defines how they're classified and labelled.
What colour and shape are COSHH symbols?
The current symbols are a red-bordered white diamond with a black pictogram inside. The older square orange-and-black symbols were withdrawn in 2017 and replaced by these diamonds.
What is the difference between the exclamation mark and the skull and crossbones?
The exclamation mark warns of less severe effects — irritation, drowsiness or an allergic skin reaction. The skull and crossbones marks acute toxicity, where a substance can be toxic or fatal even in small amounts. The skull symbol always demands the tighter controls.
This article is general guidance, not a substitute for the supplier safety data sheet or your own COSHH risk assessment. Always classify, store and control substances according to their current CLP labelling and the relevant UK regulations.