Warning and hazard characters
The classic hazard symbols are few, famous and strictly defined: a trefoil for radiation, a horned crescent for biohazards, a skull for poison. This page collects the typeable warning characters — each one copies in a click — with the meaning and origin of every sign, plus an honest section on the regulated safety pictograms (like the flame for flammables) that are printed images rather than keyboard characters. Use the copies for labels, notes, documents and teaching; real-world hazard signage follows official standards, as the note at the end explains.
Copy the warning symbols
Meanings and origins
| Symbol | Name | Code | Meaning and origin |
|---|---|---|---|
| ⚠ | Warning sign | U+26A0 | The general danger symbol for text: an exclamation in a triangle — “attention, a hazard or condition follows”. The all-purpose caution mark when no specific hazard sign applies. |
| ☢ | Radioactive sign | U+2622 | The trefoil: a central disc with three 60° blades, designed in 1946 at Berkeley to suggest activity radiating from an atom. The universal radioactive symbol — also called the radiation symbol — on containers, areas and equipment involving ionising radiation. |
| ☣ | Biohazard sign | U+2623 | Three interlocked crescents around a central disk, designed in 1966 by Charles Baldwin so it would be memorable, unique and readable upside down. The biohazard symbol marks infectious biological material. |
| ☠ | Skull and crossbones | U+2620 | Poison and mortal danger — the oldest mark in this set, from gravestones and pirate flags to chemical labels, where it means acute toxicity. |
| ⚡ | High voltage sign | U+26A1 | The lightning bolt: electrical hazard — and, in everyday text, energy and speed. On equipment it means dangerous voltage; context decides which reading applies. |
| ♨ | Hot spring | U+2668 | Steam rising from water — Japan’s onsen mark, used more widely for hot surfaces and steam in signage-style text. |
Signage emoji
These four are emoji rather than text symbols — they render in colour and serve the prohibition and fire corners of warning design:
The pictograms that are NOT keyboard characters
Chemical labels worldwide use the GHS system — red-diamond pictograms defined by regulation. Three of them answer common searches, and honesty matters here: they exist as printed images, not as Unicode characters you can type.
| Search | The regulated pictogram | Closest typeable mark |
|---|---|---|
| Flammable symbol | GHS02 — a black flame on white in a red diamond: flammable gases, liquids and solids. | 🔥 (emoji fire) for informal text; ⚠ for a text-only caution. |
| Harmful symbol | GHS07 — an exclamation mark in a red diamond: harmful/irritant substances (the old EU “harmful” mark was an X in an orange square, retired in 2015). | ⚠ — the exclamation’s text cousin. |
| Toxic symbol | GHS06 — skull and crossbones in a red diamond: acute toxicity. | ☠ — the same artwork, typeable. |
So the hazard symbols split cleanly in two: the Unicode set above (born for print, now typeable) and the regulated pictogram set (born for labels, still print). Copy the first set freely; reproduce the second only as the official artwork when a real label requires it.
Safety note: symbols copied from this page suit notes, documents, teaching and informal labels. Actual hazardous materials, workplaces and transport follow legal signage standards (GHS, ISO 7010 and local law) — a copied character is never a substitute for compliant safety signage where one is required.
Explore more
Names and codes for the wider symbol world live in the symbol names and meanings guide; the ⚕-adjacent family of sign systems continues in the gender symbols (another set of signs with scientific roots), and pictorial marks of every kind gather on the emoji copy and paste hub. The loop on every bin and bottle has its own page too: recycling symbol, with the plastic codes 1–7 honestly translated.
Frequently asked questions
What is the radiation symbol called?
The trefoil ☢ (U+2622) — three blades around a central disc, designed in 1946. “Radioactive sign” and “radiation symbol” name the same mark.
Who designed the biohazard symbol?
Charles Baldwin, in 1966, working with Dow Chemical and the NIH — the brief was a symbol that was unique, memorable and identical from every angle.
Is there a Unicode character for the flammable symbol?
No — the flammable pictogram (GHS02, a flame in a red diamond) is regulated artwork, not a character. In informal text, the fire emoji 🔥 is the usual stand-in.
What does ⚠ mean in a document?
A general warning: read what follows carefully — a hazard, a condition or an exception. It is the text equivalent of the triangular road and workplace caution signs.
Can I use these symbols on product labels?
For informal labels and notes, yes. For regulated products and workplaces, official pictograms and standards apply — see the safety note above.