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You are here:  HOME  >  What is Ionizing Radiation?

What is Ionizing Radiation?

Jump to:  Ionization | Effects | More information

The word "radiation" refers to energy that emanates, or radiates, from a source and travels through space with the possibility of depositing a fraction of its energy in any matter it encounters.

There are many kinds of radiation. Familiar ones are radio waves that allow us to communicate long distances via phones, televisions, and satellites. Microwaves are used in communications as well as in microwave ovens. Visible light waves are those we can see reflected by matter, including raindrops that reflect the colors of a rainbow.

These and similar types of radiation belong to the category known as nonionizing radiation. They are considered nonionizing because the individual waves have too little energy to cause ionization (the stripping of electrons from atoms, which breaks the chemical bonds of molecules, which give matter structure).

Ionizing radiation, on the other hand, is capable of stripping electrons from atoms and breaking chemical bonds, creating highly reactive ions (atoms or molecules that have an electric charge). Radioactive materials, those that contain atoms that have unstable nuclei, occur naturally and emit ionizing radiation in a process known as radioactive decay.

The most common types of ionizing radiation are alpha particles, beta particles, gamma rays, and x-rays. The particles and rays cannot be seen, heard, tasted, smelled, or felt, which is why ionizing radiation remained undiscovered until the late 1800s even though many ordinary materials emit small amounts.

Natural sources include the soil, water, air, food, and building materials. Man-made devices such as x-ray machines also produce ionizing radiation. Potential sources include nuclear accidents involving medical or industrial nuclear material or terrorist actions involving nuclear devices.

At high enough doses, ionizing radiation can damage molecules such as DNA in cells. Damage to DNA and other important cellular components can result in cell damage or cell death. This can lead to health effects like an increase in cancer risk and, at extremely high doses, death.

At the same time, ionizing radiation has many practical applications such as in medical imaging using x-rays and CT (computerized tomography) scans. It is used in radiation therapy to treat tumors and leukemia. It is used to sterilize many products including some types of food, and it is used in many common items such as smoke detector sensors.

More information
To learn more about ionizing radiation, see the U.S. Nuclear Regulatory Commission fact sheet and additional information at the NRC Web site.

Related AFRRI content:
Military veterans' radiation exposure  |  Radiation countermeasures  |  Research articles  |  AFRRI Pocket Guide

Information developed by AFRRI staff, 2014