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Radiation Safety Index > Magnetic Fields & Radio Frequency

Electrical devices and systems produce two different fields: an electric field like the one produced on the surface of a wool sweater on a dry winter day, and a magnetic field like the fields produced by a compass needle, a small magnet or the earth itself. These fields in combination are referred to as electromagnetic fields or EMF. EMF fields associated with electrical devices and appliances are produced only when the device is plugged in and operating. Devices which generate electromagnetic fields include radio or TV station transmitters, microwave ovens, power transmission lines, and electrical appliances.

Radiofrequency (RF) and microwave (MW) radiation are electromagnetic radiation in the frequency ranges 3 kilohertz (kHz) - 300 Megahertz (MHz), and 300 MHz - 300 gigahertz (GHz), respectively. RF and MW radiation are non-ionizing in that there is insufficient energy to ionize atoms. The primary health effect of RF/MW energy is a result of heating. The absorption of RF/MW energy varies with frequency. Microwave radiation is absorbed near the skin, whereas RF radiation may be absorbed in deep body organs. Exposure standards are based on preventing thermal problems. However, research continues on possible "non-thermal" effects. Use of RF/M radiation includes: radios, cellular phones, processing and cooking of foods, heat sealers, vinyl welders, high frequency welders, induction heaters, flow solder machines, communications transmitters, radar transmitters, ion implant equipment, microwave drying equipment, sputtering equipment and glue curing.

Exposure to the very high intensity electromagnetic fields found in the immediate vicinity of certain sources such as radar installations and TV or radio transmitters can produce electrical shock or a variety of heating effects, which may range from a sensation of warmth to burns and eventual cataract formation.

The National Research Council conducted a review of the many studies which have examined the effects and risks of exposure to low intensity EMF. The Council's conclusion, in a report released on October 31, 1996, states that "No clear convincing evidence exists to show that residential exposures to electric and magnetic fields (EMFs) are a threat to human health." The nature of most of the exposures to individuals at Brown University are comparable to residential exposures, i.e., exposures to common electrical devices and appliances which do not produce unusually high intensity EMFs. However, there is one category of equipment that needs special attention, namely Nuclear Magnetic Resonance (NMR).

For more information please refer to the following links::

NMR Safety -


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Last updated on 12/11/2014