Nonionizing

Nonionizing refers to electromagnetic radiation whose photons do not have enough energy to ionize atoms under typical conditions. Ionizing radiation, by contrast, has sufficient energy to remove electrons from atoms and can cause chemical changes that may damage biological tissue. The distinction is pragmatic and context-dependent, but nonionizing radiation is generally considered to include radio waves, microwaves, infrared, visible light, and near ultraviolet, while ultraviolet-C and higher-energy photons are typically treated as ionizing in safety contexts.

Common types and uses of nonionizing radiation include radio waves and microwaves used for communication, radar, and cooking; infrared radiation used in heating and thermal imaging; and visible light used for lighting and vision. Near ultraviolet radiation is included in this category in many contexts, although the shortest-wavelength ultraviolet light (UV-C) is often handled as ionizing for safety purposes.

Interactions and effects from nonionizing radiation are primarily through heating and, at higher intensities, through photochemical or dielectric effects that do not involve electron removal. At ordinary exposure levels, nonionizing radiation is generally considered less likely to cause direct DNA damage than ionizing radiation. However, high-power or prolonged exposure can lead to thermal injury, eye damage, or other tissue effects, depending on wavelength, power, and duration.

Safety and standards organizations regulate nonionizing exposure to limit thermal and related hazards. Guidelines cover various sources, including communication devices, industrial heating, and consumer electronics, aiming to minimize adverse health effects while allowing beneficial uses of the technology.