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U.S. Department of Health & Human Services
Radiation Emergency Medical Management (REMM)

Examples of Radiation Signs and Symbols for Work Areas, Buildings, Transportation of Cargo
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Basic Radiation Tri-Foil Sign

Tri-Foil Sign
  • International symbol of radiation, usually accompanied by more specific text.
  • Symbol can be magenta or black, on a yellow background.
  • Sign must be posted where radioactive materials are handled or where radiation-producing equipment is used.
  • Sign is used as a warning to protect people from being exposed to radioactivity.

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New Ionizing Radiation Warning Symbol from the International Organization for Standardization (ISO) and International Atomic Energy Agency (IAEA)

New Ionizing Radiation Warning Symbol from ISO and IAEA
  • On February 15, 2007, the International Organization for Standardization (ISO) and the International Atomic Energy Agency (IAEA) launched a new radiation warning symbol entitled the "Ionizing-Radiation Warning — Supplementary Symbol."
  • The symbol is also called ISO Standard #21482.
  • According to ISO and IAEA, the goal of the new symbol is "to help reduce needless deaths and serious injuries from accidental exposure to large radioactive sources."
  • The new symbol is intended to supplement the existing, well recognized, radiation trefoil symbol, which the IAEA has said has "no intuitive meaning and little recognition beyond those educated in its significance."
  • The new symbol has been designed to convey the message "Danger — Stay Away" to anyone who sees it, regardless of their age, education, or cultural background.
  • IAEA has said the following about the new warning symbol:
    • It is intended for IAEA Category 1, 2, and 3 sources defined as dangerous sources capable of causing death or serious injury, such as food irradiators, teletherapy machines for cancer treatment, and industrial radiography units.
    • It should be placed on the device housing the source, as a warning not to dismantle the device or to get any closer.
    • It will not be visible under normal use and will only be visible if someone attempts to disassemble the housing device.
    • It should not be placed on building access doors, transportation packages, or containers.
    • Strategies to place the symbol on existing large sources are being developed by the IAEA.

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Examples of Other Radiation Signs

Caution Radiation Area


Caution: Radioactive Handling Area


Cautions High Rem Per Hour  Sign


Caution: Neutron Radiation Area


Caution: Airborne Radioactivity


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