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Ionising Radiation

Ionising radiation consists of subatomic particles or electromagnetic waves that have sufficient energy to detach electrons from atoms or molecules, thus ionising them.

Examples of ionising particles are energetic alpha particles, beta particles and neutrons. The ability of an electronmagnetic wave (photons) to ionise an atom or molecule depends on its frequency. Radiation on the short-wavelength end of the electromagnetic spectrum is ionising, i.e. high frequency ultraviolet, xrays and gamma rays.

Ionising radiation comes from radioisotopes, x-ray tubes, particle accelerators, and is present in the environment. It is invisible and not directly detectable by human senses, so instruments such as Geiger counters are usually required to detect its presence.

Use of ionising radiation has significant benefits in academic research, industrial applications and medical research and treatment. This is despite the fact that it presents a health hazard if used improperly. Exposure to radiation causes damage to living tissue, resulting in skin burns, radiation sickness, possibly fatal at high doses and cancer, tumours and DNA damage at low doses.


Because of these risks to health, use of radioactive substances and equipment and instruments capable of producing ionising radiation is tightly regulated. This internationally recognised warning sign is always used to label radioactive substances and to identify work areas in which radiation is used.

The University sets out its requirements and arrangements in the Policy on the Use of Ionising Radiation and Radioactive Substances.

This is supported by Instructions for Open Sources, Sealed Sources and X-Ray Equipment. Information is provided on Isotope Data for Common Radionuclides. Specific guidance is provided for Women of Childbearing Age who work with ionising radiations.

Anyone whose work involves the use of ionising radiation is personally responsible for carrying out the work in compliance with University Policy and instructions.

Additional advice and support for workers using ionising radiation is available from the University Radiation Protection Officer in the Health and Safety Department and from locally appointed Radiation Protection Supervisors.