Non Ionizing Radiation [PDF]

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Different types of electromagnetic radiation Non-ionizing (or non-ionising) radiation refers to any type of electromagnetic radiation that does not carry enough energy per quantum to ionize atoms or molecules—that is, to completely remove an electron from an atom or molecule.[1] Instead of producing charged ions when passing through matter, the electromagnetic radiation has sufficient energy only for excitation, the movement of an electron to a higher energy state. Nevertheless, different biological effects are observed for different types of non-ionizing radiation.[2][3] Near ultraviolet, visible light, infrared, microwave, radio waves, and low-frequency RF (longwave) are all examples of non-ionizing radiation. Visible and near ultraviolet may induce photochemical reactions, or accelerate radical reactions, such as photochemical aging of varnishes[4] or the breakdown of flavoring compounds in beer to produce the "lightstruck flavor".[5] Near ultraviolet radiation, although technically non-ionizing, may still excite and cause photochemical reactions in some molecules. This happens because at ultraviolet photon energies, molecules may become electronically-excited or promoted to free-radical form, even without ionization taking place. The light from the Sun that reaches the earth is largely composed of non-ionizing radiation, since the ionizing far-ultraviolet rays have been filtered out by the gases in the atmosphere, particularly oxygen. The remaining ultraviolet radiation from the Sun is in the non-ionizing band, and causes molecular damage by photochemical and free-radical-producing means that do not ionize.[3]

Health risks

Non-ionizing radiation hazard sign Non-ionizing radiation can produce non-mutagenic[citation needed] effects such as inciting thermal energy in biological tissue that can lead to burns. In terms of potential biological effects, the non-ionizing portion of the spectrum can be subdivided into: 1. The optical radiation portion, where electron excitation can occur (visible light, infrared light) 2. The portion where the wavelength is smaller than the body, and heating via induced currents can occur (MW and higher-frequency RF) 3. The portion where the wavelength is much larger than the body, and heating via induced currents seldom occurs (lower-frequency RF, power frequencies, static fields).[3] [2]

Source

Wavelength Frequency Biological effects Eye – photochemical 750–950 cataract; skin – UVA Black light, sunlight 318–400 nm THz erythema, inc. pigmentation Skin photoaging; eye Lasers, sunlight, fire, LEDs, light 385–750 Visible light 400–780 nm – photochemical & bulbs THz thermal retinal injury Eye – thermal retinal 780 nm – 215–385 IR-A Lasers, remote controls injury, thermal 1.4 µm THz cataract; skin burn 100–215 Eye – corneal burn, IR-B Lasers 1.4–3 µm THz cataract; skin burn Eye – corneal burn, 3 µm – 300 GHz – IR-C Far-infrared laser cataract; heating of 1 mm 100 THz body surface PCS phones, some mobile/cell 1 mm – Heating of body Microwave phones, microwave ovens, 1–300 GHz 33 cm tissue cordless phones, motion

Radiofrequency radiation Lowfrequency RF

detectors, long-distance telecommunications, radar, Wi-Fi Mobile/cell phones, television, 33 cm FM, AM, shortwave, CB, 3 km cordless phones Power lines

Static field[3] Strong magnets, MRI

– 100 kHz 1 GHz

>3 km