Wireless electronic devices and health
From Wikipedia, the free encyclopedia
- For mobile phones, see Mobile phone radiation and health
With the focus on health concerns of mobile phones, people are also questioning the health risks of other wireless devices now being increasingly used at work and in the home, such as wireless local area networks, DECT and other cordless phones, Bluetooth devices, and so on.
According to the study currently being carried out by the World Health Organization (http://www.who.int/peh-emf/en/)
- "Electromagnetic fields of all frequencies represent one of the most common and fastest growing environmental influences, about which anxiety and speculation are spreading. All populations are now exposed to varying degrees of EMF, and the levels will continue to increase as technology advances. As part of its charter to protect public health and in response to public concern, the World Health Organization (WHO) established the International EMF Project in 1996 to assess the scientific evidence of possible health effects of EMF in the frequency range from 0 to 300 GHz."
International guidelines on exposure levels to microwave frequency EMFs such as ICNIRP limit the power levels of wireless devices and it is not common for wireless devices to exceed the guidelines. However, these guidelines have been criticised as they do not take into account non-thermal effects (by ICNIRP's own admission).
"Professor Sir William Stewart, chairman of the Health Protection Agency, said that evidence of potentially harmful effects of microwave radiation had become more persuasive over the past five years. His report said that while there was a lack of hard information of damage to health, the approach should be precautionary."[1]
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[edit] Wireless LAN
Although it is generally agreed that EMF levels for wireless LAN devices are lower than mobile phones, there seems to exist less public awareness of the health issues for wireless LAN devices than there is for mobile phones. Most wireless LAN equipment is designed to work within predefined standards. Wireless LANs work by setting up microwave communication, usually in narrow frequency bands around 2.4 and 5.8 GHz, depending on the protocol that is used (WiFi, WiMax, OFDM, etc). The system is comprised of a base station (called access point, or AP) which establishes point-to-multipoint communication with a number of subscriber units or SUs, to which client computers are connected. Both devices are bidirectional and have antennas that emit at a certain RF power. By definition, the SU stands very near to the computer operator, and the communication link is constant, i.e., not only when there is a call, such as in a mobile phone. In small work and home environments, the AP is also often in close proximity to humans. The transmission power of a typical wireless access point is around 35 mW, although common standards allow for power levels up to 200 mW. It is difficult to compare this to a mobile phone because the power levels of mobile phones can vary enormously depending on proximity to a mobile phone mast, but in urban areas mobile phones also typically operate at this power level, despite being able to go up to 2 W if they have a poor signal.
[edit] Bluetooth
Bluetooth uses also the microwave frequency spectrum in the range of 2.4 GHz to 2.4835 GHz. The radiated output power of Bluetooth devices is very low in power, so it is assumed that the potential health consequences are lower than other wireless devices.[citation needed] Bluetooth devices can operate continuously or sporadically (on demand), so total exposure to EMF radiation is very variable.
[edit] Other devices
Radiofrequency in the microwave and radio spectrum is used in a number of practical devices for professional and home use, such as:
- DECT and other cordless phones operating at a wide range of frequncies
- Remote control devices for opening gates, etc.
- Portable two-way radio communication devices, such as walkie-talkies
- Wireless security (alarm) systems
- Wireless security video cameras
- Radio links between buildings for data communication
In addition, electrical and electronic devices of all kinds emit some sort of EM fields around its working circuits, generated by oscillating currents. Humans are in daily contact with computers, video display monitors, TV screens, microwave ovens, fluorescent lamps, electric motors of several kinds (such as washing machines, water pumps, etc.) and many others. The typical background power of EM fields in the the home can vary from zero to 5 milliwatts per meter squared, but is not uncommon for it to be found up to 100 milliwatts per meter squared near mobile phone masts[citation needed]. Long time effects of these EM fields on human and animal health are still unknown, and most of the studies available are only short-term studies which have shown no effect. Some people report electrical sensitivity, feeling ill effects at exposure levels much lower than international guidelines.
[edit] Alternatives
Wireless transmission can be carried on visible or infrared light without inducing electrical currents in human body. Wireless LAN can be built from Free Space Optics. However this has limitation of being point to point only. Bluetooth can be replaced in some applications by IrDA. There are infrared wireless headsets. Mobile phones, wireless LAN in laptops and other application where penetration through obstacles or wide coverage together with high speed is required, cannot be replaced with existing technology. Television and radio cannot be replaced with existing technology either.
