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ICRPAEDIA: What is Ionising Radiation?

  WHAT IS IONISING RADIATION?  

Radiation is energy in motion, in the form of moving waves or particles.

Radiation with enough energy to knock an electron from an atom is called ionising radiation. This means ionising radiation can break chemical bonds, such as those in DNA.

There are three main types of ionising radiation:

Alpha particles (α) cannot penetrate a piece of paper or the outer layer of dead cells on our skin

Beta particles (β) can penetrate short distances into tissues

Gamma rays (γ), sometimes referred to as photons, can penetrate substantial depths in tissue, or even pass right through the body depositing only some of its energy as it passes through

More exotic types of radiation also exist, and are sometimes important in radiological protection, including: neutrons, muons, protons, fission fragments, and heavy nuclei


The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) is the leading international body on radiation levels and effects. Visit the UNSCEAR website or read the UNEP report on "Radiation Effects and Sources" based on UNSCEAR work to learn more.


▶ Further Reading: Quotes from ICRP Publications