Symbols whose entire purpose is to warn of a physical hazard before someone encounters it — the nine UN GHS chemical-labelling pictograms plus the two ISO biological and ionising-radiation trefoils. They share a warning function and a deliberate design goal of instant recognition, but are governed by separate standards bodies: the GHS pictograms are a single coordinated chemical-labelling set with a common red-bordered diamond frame, while the biohazard and radiation trefoils are independent ISO safety symbols that predate GHS and follow their own colour and shape conventions.
A black exploding-bomb icon in a red-bordered diamond, the GHS symbol for explosive hazard.
A black flame icon in a red-bordered diamond, the GHS symbol for flammable hazard.
A black flame above a black circle in a red-bordered diamond, the GHS symbol for oxidizing hazard.
A black gas cylinder icon in a red-bordered diamond, the GHS symbol for gases under pressure.
An image of a substance corroding a surface and a hand, in a red-bordered diamond — the GHS symbol for corrosive hazard.
A black skull and crossbones in a red-bordered diamond, the GHS symbol for acute toxicity.
A black exclamation mark in a red-bordered diamond, the GHS symbol for lower-level health/physical hazards or irritation.
A black human silhouette with a starburst on the chest, in a red-bordered diamond — the GHS symbol for serious, longer-term health hazards.
A black image of a dead fish and tree in a red-bordered diamond, the GHS symbol for aquatic/environmental hazard.
A trefoil of overlapping circles, designed to be instantly recognisable as a warning for biological hazards.
A three-bladed trefoil, conventionally black on a yellow background, warning of ionising radiation hazards.