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The pair that makes the safety-sign colour convention legible rather than arbitrary.
Both mark equipment kept for an emergency, and the colour is the classification rather than a design choice. Green is the safe-condition class — where safety is, where help is, where the way out is. Red on a safety sign means firefighting equipment, and the same red square marks a hose reel, an alarm call point and a fire telephone. A green extinguisher sign or a red first-aid sign would both be wrong under the standard, and learning this one pair teaches the whole colour system.
Both mark equipment kept for an emergency, and the colours say which kind: green is where safety is, red is where firefighting equipment is.
Drawn from the visual attributes recorded for each symbol. Only traits the two records disagree about are listed.
| Trait | First aid symbol | Fire extinguisher symbol |
|---|---|---|
| Built from | crosses and squares | objects and squares |
| Colour | green and white | red and white |
| Symmetry | radial | none |
| First aid symbol | Fire extinguisher symbol | |
|---|---|---|
| Sign class | Safe condition — green | Fire equipment — red |
| Standard reference | ISO 7010 E003 | ISO 7010 F001 |
| What else shares the colour | Emergency exit, assembly point, defibrillator, safety shower | Hose reel, fire alarm call point, fire telephone |
| What the sign does not tell you | Who is trained, or what the kit contains | Which fire class the extinguisher suits — that is on the body of the extinguisher |
| Relationship (from Symbolwise's records) | Commonly confused with Fire extinguisher symbol — Both mark equipment kept for an emergency, and the colours say which kind: green is where safety is, red is where firefighting equipment is. | Commonly confused with First aid symbol — Red marks firefighting equipment; green marks safety and first aid. |
ISO 7010, Graphical symbols — Safety colours and safety signs
International Organization for Standardization · retrieved 2026-08-02
Paywalled and NOT READ in full. Registered so records can state that a sign has a standard reference and a defined shape and colour — E003 for first aid, E010 for a defibrillator. The catalogue of registered signs and their reference numbers is public even where the standard text is not. See docs/paywalled-standards.md.
ISO 3864, Graphical symbols — Safety colours and safety signs
International Organization for Standardization · retrieved 2026-08-22
Paywalled and NOT READ in full. Registered so records can state that the safety-sign colour and shape conventions — green for safe condition, red for prohibition and fire equipment, yellow for warning, blue for mandatory action — are set by a standard rather than by convention. See docs/paywalled-standards.md.
Wikipedia · retrieved 2026-07-31
Tertiary reference. Used for what the symbol depicts, its shape-and-colour category, and any ISO reference number it reports. The standards themselves are paywalled and were not consulted, so nothing here is treated as an official definition.
A building's assembly point is a safe place to stand once you are outside. A ship's muster station is a staffed step in a procedure: you are counted against a roll, briefed, and if necessary allocated to a survival craft, which is why it has a letter or a number and appears on your cabin door card. Both are green, both show grouped figures, and both are called an assembly point in ordinary speech — and treating a muster station as somewhere merely to wait is the misunderstanding drills exist to correct.
The becquerel counts nuclear decays — one per second — and says nothing about harm. The sievert weights absorbed energy by the kind of radiation delivering it, and so estimates biological effect. A becquerel of one isotope and a becquerel of another can carry very different risk, which is exactly why exposure limits and medical doses are stated in sieverts and never in becquerels.
Count what is around the centre. Three solid blades radiating from a small disc is ionising radiation; three broken rings overlapping a central circle is biological hazard. They are the same size, the same colours and the same three-fold arrangement, which is why signage catalogues themselves get them wrong — and the responses could not be less alike. One calls for distance, shielding and time; the other for containment, disinfection and a disposal route.
The plain black flag excludes the competitor: their race is over. The black flag with an orange disc reports a mechanical problem that endangers others and sends the driver to the pits to have it fixed, after which they may rejoin. Both are shown with a number board, both are black, and confusing them costs a competitor a race they could have finished.