Environmental and background radiation

• Radiation surrounds us in our environment.
• In Western Australia, legislation specifies dose limits for ionising radiation.

Radiation can be considered in two distinct categories:

1. ionising radiation
2. 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, infra red radiation as well as visible light and is also used in communication technologies as radio frequency radiation.

The International Commission for Radiological Protection (ICRP) (external site) recommends 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 Radiological Council (external site) website contains a downloadable fact sheet.

Environmental radiation

Naturally occurring material on the earth’s surface contributes to background radiation. These materials can be described by the following environmental radionuclides:

• 238U (uranium)
• 232Th (thorium)
• 40K (potassium).

The element radon, which exists in gaseous form, is one of the better known examples associated with the uranium series which contributes to background radiation.

Different geological regions will have different contributions of the radionuclide series to make up the overall background radiation.

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.

More information 

Environmental Health Directorate – Radiation Health
Phone: 9388 4999
Fax: 9382 0701
Email: Radiation Health

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