COSHH symbols are the red-bordered diamond hazard pictograms you see on chemical containers. There are nine of them, and they come from the CLP Regulation (Classification, Labelling and Packaging), not from COSHH itself — though they are almost universally called “COSHH symbols” in UK workplaces. Each pictogram tells you, at a glance, what type of harm a substance can cause.
This guide explains what each symbol means, which ones signal the most serious health risks, and what the older orange symbols were replaced by.
What are the 9 hazard pictograms?
| Pictogram | Name | What it warns about |
|---|---|---|
| Exploding bomb | Explosive | Substances that can explode — unstable explosives, some organic peroxides |
| Flame | Flammable | Catches fire easily — solvents, fuels, aerosols, some adhesives |
| Flame over circle | Oxidising | Can cause or intensify fire in other materials |
| Gas cylinder | Gas under pressure | Compressed, liquefied or refrigerated gases; risk of burst or cold burn |
| Corrosion | Corrosive | Destroys skin and eye tissue; may corrode metals — strong acids and alkalis, drain cleaners |
| Skull and crossbones | Acute toxicity | Can cause serious harm or death from a single, short exposure |
| Exclamation mark | Harmful / irritant | Skin or eye irritation, skin sensitisation, drowsiness |
| Health hazard | Serious health hazard | Long-term effects — carcinogens, mutagens, reproductive toxicity, respiratory sensitisers |
| Environment | Hazardous to the environment | Toxic to aquatic life |
Which COSHH symbols matter most for health?
Three of the nine relate directly to health harm, and they are worth being able to tell apart:
The health hazard pictogram (silhouette with a starburst)
This is the most serious of the health symbols and the most commonly misread. It signals long-term, often irreversible effects: substances that may cause cancer, damage fertility or the unborn child, cause genetic defects, or cause asthma when breathed in (respiratory sensitisers). Wood dust, silica and some welding fumes fall into this territory.
The skull and crossbones (acute toxicity)
Signals that a small quantity can cause serious harm or death quickly — by swallowing, skin contact or inhalation. Far less common in general workplaces than the other two.
The exclamation mark (harmful / irritant)
Signals less severe but still genuine effects: skin and eye irritation, allergic skin reactions, or drowsiness. Many everyday cleaning products carry this pictogram.
A practical rule: the skull warns you about today; the health hazard silhouette warns you about the next twenty years.
What happened to the old orange COSHH symbols?
Older UK workplaces will remember square orange-and-black hazard symbols. These came from earlier European classification rules and were phased out following the introduction of the CLP Regulation, which aligned Europe with the UN’s Globally Harmonised System (GHS).
The orange symbols were replaced by the red-bordered white diamonds described above. The change was not just cosmetic — some classifications and thresholds changed too. If you still have containers with orange labels, they are almost certainly beyond their shelf life and should be reviewed.
Do hazard symbols tell you everything you need to know?
No — and treating them as the whole story is a common mistake. Pictograms tell you the type of hazard, not the level of risk in your particular job. The same product can be low-risk used occasionally with good ventilation and high-risk used all day in a confined space.
For the full picture you need:
- Hazard statements (the “H” codes next to the pictogram) — these are specific, e.g. H350 “May cause cancer”
- Precautionary statements (“P” codes) — what to do about it
- The safety data sheet — particularly section 8 (exposure controls) and section 11 (toxicological information)
- Your COSHH assessment — which considers how your work uses the substance
And remember that many workplace hazards arrive with no label at all. Silica dust from cutting paving, wood dust from sanding, and welding fume are all created by the work itself — no container, no pictogram, but all capable of causing serious lung disease.
Where must hazard symbols appear?
Suppliers must label hazardous products with the appropriate pictograms, signal word (“Danger” or “Warning”), hazard statements and precautionary statements. Labels must not be removed or obscured.
A practical point often missed: if you decant a substance into a different container — a spray bottle, a bucket, an unmarked can — that container needs labelling too. Unlabelled decanted chemicals are a recurring cause of workplace injury.
Further reading
Learn COSHH properly
Hazard symbols are one part of COSHH. Our COSHH Awareness course also covers hazardous substances, routes of exposure, the hierarchy of control and how COSHH assessments work.
Related reading: What is COSHH? A complete guide.
£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 awareness course. Where your role or scheme requires a regulated qualification or licence, that must come from an approved provider — always check your employer’s or scheme’s specific requirements.