Electromagnetic radiation hazard

Electromagnetic radiation can be classified into ionizingradiation and non-ionizing radiation, based on whether it is capable of ionizing atoms and breaking chemical bonds. Ultravioletand higher frequencies, such as X-raysor gamma raysare ionizing. These pose their own special hazards: see radiation and radiation poisoning.

Non-ionizing radiation, discussed here, is not capable of having these effects on molecules. There are three major potential hazards associated with non-ionizing electromagnetic radiation: electrical, fire, and biological. Additionally, inducedcurrent caused by radiation is a significant danger in the handling of electrically initiated explosives or pyrotechnics. This risk is commonly reffered to as RadHaz or HERO(Hazards of Electromagnetic Radiation to Ordnance).

Electrical hazards

Strong electromagnetic fieldscan generate an electric currentin other metal objects by electromagnetic induction. The induced current can cause an electric shock to persons or animals. It can also overload and destroy electrical equipment. This can be a particular hazard in the vicinity of explosives, since an electrical overload might ignite it.

Fire hazards

Again by electromagnetic induction, a strong electromagnetic fieldcan cause electric currents which may flow across an air gap to ground, causing sparks. These sparks can then ignite flammable materials or gases, possibly leading to an explosion or a fire.

Biological hazards of EMF

The best understood biological effect of electromagnetic fields is to cause dielectric heating. For example, touching an antennawhile a transmitteris in operation can cause severe burns. Birds sitting on very high-power antennas when transmission begins can be instantly cooked by RFenergy. In fact, that is the principle behind the operation of a microwave oven.

This heating effect varies with the frequencyof the electromagnetic energy. The eyes are particularly vulnerable to RF energy in the microwaverange, and prolonged exposure to microwaves can lead to cataracts. Each frequency in the electromagnetic spectrumis absorbed by living tissue at a different rate, called the specific absorption rateor SAR, which has units of watts per kilogram (W/kg). The IEEEand many national governments have established safety limits for exposure to various frequencies of electromagnetic energy based on SAR.

There is also a substantial body of evidence for complex biological effects of weaker non-thermal electromagnetic fields (see Bioelectromagnetics), including weak ELF magnetic fields and modulated RF and microwave fields. The mechanism of action of non-thermal electromagnetic fields is not well understood, although a number of hypotheses have been proposed. Non-thermal effects may be beneficial or harmful depending on the specific parameters of the field, but since they are not well understood, a precautionary principle approach would suggest minimizing exposure whenever possible.

Some studies have even suggested that a small percentage of the population may be electromagnetically sensitive and can consciously react to very low level fields even in double-blind experiments. It does not seem to be a congenital condition and theories have been put forth that some form of external trigger such as previous chemical exposure may bring about the sensitivity.

For more information on EMF surveys:

EMF Survey FAQ Page

U.S. military definition

In Federal Standard 1037C, the United Statesgovernment adopts the following definition:

Electromagnetic radiation hazards (RADHAZ or EMR hazards): Hazards caused by a transmitter/antenna installation that generates electromagnetic radiationin the vicinity of ordnance, personnel, or fueling operations in excess of established safe levels or increases the existing levels to a hazardous level; or a personnel, fueling, or ordnance installation located in an area that is illuminated by electromagnetic radiation at a level that is hazardous to the planned operations or occupancy. These hazards will exist when an electromagnetic fieldof sufficient intensityis generated to: (a) induce or otherwise couple currents and/or voltages of magnitudes large enough to initiate electroexplosive devices or other sensitive explosive components of weapon systems, ordnance, or explosive devices; (b) cause harmful or injurious effects to humans and wildlife; (c) create sparks having sufficient magnitude to ignite flammable mixtures of materials that must be handled in the affected area.

—Department of Defense Dictionary of Military and Associated Terms

See also

• Mobile phone radiation and health
• Wireless electronic devices and health
• Specific absorption ratede:Elektrosmog

This article is licensed under the GNU Free Documentation License.
It uses material from the http://en.wikipedia.org/wiki/Electromagnetic+radiation+hazard Wikipedia article Electromagnetic radiation hazard.