Non-ionising radiation (or in American English non-ionizing radiation) refers to any type of electromagnetic radiation that does not carry enough energy to ionize living material - that is, to completely remove an electron from an atom or molecule.
The composition of this radiation can vary depending on what may be ionized. Visible light, near ultraviolet, infrared, and radio waves are all examples of non-ionising radiation, though visible and near ultraviolet can also ionize some molecules. The light from the sun that reaches the earth is largely composed of non-ionising radiation, with the notable exception of some ultraviolet rays. However, most ionizing radiation is filtered out by the atmosphere.
Because it is lower energy radiation, the use of this type of radiation in medical fields and everyday life poses fewer health risks than ionizing radiation in forms such as x-rays. However, some studies have shown that long-term exposure to low-frequency electromagnetic fields (such as those produced by some power lines) can pose a health risk, though the radiation itself is non-ionising.
See also