ISO 21482 is a standard that specifies a warning symbol to warn against the dangers of radiation. The warning is made of the trefoil on the top, which warns against radiations. There are lines towards the bottom. On the bottom left, there is a skull, which warns against poison. On the bottom right, there is a running figure, and an arrow pointing outside the sign. The color red was chosen because children said it expresses danger better than yellow. The Gallup Organization recommended the symbol, after showing it to 1650 people.
The new symbol does not replace the old one, but it amends it. It was designed to show the danger of radiation to people who do not know about radiation, or who do not know the symbol for it. The symbol was developed because of nuclear accidents that happened because people opened containers with radioactive materials, such as the Goiânia accident in 1987, or the Samut Prakan disaster near Bangkok in 2000. The new symbol will not be placed on the containers. Rather, it will directly placed on the substances emitting radiation, of the highest categories, 1 to 3. Containers will continue to bear only the old symbol, as they do not pose a direct risk. This also applies to rooms with radiation sources or x-ray equipment in them.