Ionising radiation hazard symbol

2007 ISO radioactivity danger logo. This logo was designed in part for long-term radioactive waste depositories which might survive into a far future time in which all knowledge of the meaning of present common radiation danger symbols and signs will have been lost.

Ionizing radiation is a process in physics where something sends out particles or waves that can ionize an atom or molecule through atomic interactions.

The strength of ionizing radiation depends on the energy of the individual particles or waves, and not a function of the number of particles or waves present. The material that the radiation can ionize depends on the ionization energy of the material.

Ionizing radiation can be electromagnetic radiation or subatomic particles. Electromagnetic:

• Gamma rays are electromagnetic waves of highest energy.
• X-rays are less energetic.
• Ultraviolet radiation only ionizes some materials.

Subatomic particle radiation includes:

• Alpha particle radiation, made of helium nuclei
• Beta particle radiation, made of energetic electrons or positrons
• Neutron radiation, made of neutrons