About radiation

Radiation can be classified as ionizing or non-ionizing. Ionizing radiation has sufficient energy to remove electrons from atoms or molecules. Radiation that has enough energy to move or vibrate atoms, but not enough to remove electrons, is called non-ionizing radiation.

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Sources of radiation

Sources of naturally occurring radiation include:

Radiation can also be generated by artificial sources, including:

Ionizing radiation

As unstable atoms decay, they release radiation in the form of electromagnetic waves and subatomic particles. Some forms of this radiation can detach electrons from, or ionize, other atoms as they pass through matter. This is referred to as ionizing radiation.

Sources of ionizing radiation exposure

Every day, Canadians come in contact with ionizing radiation in their living and work environments.

Canadians are exposed to naturally-occurring radiation in the environment from rocks and soil, as well as cosmic radiation from space. These sources of radiation are referred to as "background" radiation.

Ionizing radiation can also be generated from artificial sources including medical or clinical devices, such as X-ray machines and CT scanners.

Exposure levels in Canada

The average Canadian is exposed to between 2 and 3 millisieverts (mSv) of radiation annually from background radiation.

Here are a few examples of radiation levels from various sources:

Non-ionizing radiation

On a daily basis, Canadians are exposed to non-ionizing radiation generated by household wiring, lighting, and electrical appliances such as microwave ovens, hair dryers, and toasters. In the workplace, common sources include computer monitors, photocopiers, fax machines, and fluorescent lights. Power lines and electric tools also a form of non-ionizing radiation. Some medical applications of non-ionizing radiation include short-wave diathermy and magnetic resonance imaging (MRI).

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