Radiation surrounds us in our environment and can be considered in two distinct categories; ionising radiation and non-ionising radiation. The higher energies associated with ionising radiation presents a recognised risk of tissue damage in humans. Ionising radiation originates from cosmic radiation, radioactive substances and is also generated from x-ray devices. Non-ionising radiation is generated from the sun as ultraviolet radiation, infrared radiation as well as visible light and is also used in communication technologies as radiofrequency radiation. Basic approaches for ionising radiation protection are consistent around the world with the International Commission for Radiological Protection (ICRP) recommending that any exposure above natural background be kept as low as reasonably achievable and below the recommended individual dose limits.
In Western Australia, legislation specifies dose limits for ionising radiation. Legislation also specifies maximum exposure limits for non-ionising radiation. For up-to-date information on the dose limits and maximum exposure limits in Western Australia, the website of the Radiological Council contains a downloadable fact sheet.
Environmental radiation
The most abundant contributions to background radiation that occur naturally from the material of the earth’s surface may be described by the following environmental radionuclides: 238U (uranium), 232Th (thorium), and 40K (potassium). One of the better known examples associated with the uranium series and contributing to background radiation is the element radon that exists in gaseous form. Different geological regions will have different contributions of the radionuclide series to make up the overall background radiation.
For general information about background radiation considerations for Western Australia, please contact the Radiation Health Branch for further assistance on (08) 9346 2260.
Cosmic radiation
Another component of the measurable background in our environment is cosmic radiation. Cosmic radiation contributes to our natural background in varying amounts that depend on altitude and to a certain extent on latitude. It is acknowledged that air travel provides small increases in the overall contribution to background radiation.
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