Radiation Hazard Symbol - Meaning, History, and Safety Use #2216038 (License: Personal Use)

This black trefoil symbol, consisting of three blades arranged at 120-degree angles around a central circle, was created in 1946 at the University of California, Berkeley, to denote radioactive materials or ionizing radiation zones. It is standardized by ISO 361 and IAEA guidelines and appears on containers, doors, equipment, and signage in nuclear facilities, medical imaging labs, and industrial settings. The design ensures high visibility and immediate recognition, even across language barriers.

Used on safety signage, packaging labels, facility entrances, and educational materials to warn of radiation risks; matches user intent for hazard identification, safety compliance, academic research, or emergency preparedness guidance.