Mobile Phone Radiation and Health - Health Hazards of Base Stations

Health Hazards of Base Stations

Another area of concern is the radiation emitted by the fixed infrastructure used in mobile telephony, such as base stations and their antennas, which provide the link to and from mobile phones. This is because, in contrast to mobile handsets, it is emitted continuously and is more powerful at close quarters. On the other hand, field intensities drop rapidly with distance away from the base of transmitters because of the attenuation of power with the square of distance.

One popular design of mobile phone antenna is the sector antenna, whose coverage is 120 degrees horizontally and about +-5 degrees from the vertical.

Because base stations operate at less than 100 watts, the radiation at ground level is much weaker than a cell phone due to the power relationship appropriate for that design of antenna. Base station emissions must comply with safety guidelines (see Safety standards and licensing below). Some countries however (such as South Africa for example) have no health regulations governing the placement of base stations.

Several surveys have found a variety of self-reported symptoms for people who live close to base stations. However, there are significant challenges in conducting studies of populations near base stations, especially in assessment of individual exposure. Self-report studies can also be vulnerable to the nocebo effect.

Two double-blind placebo-controlled trials conducted at the University of Essex and another in Switzerland concluded that mobile phone masts were unlikely to be causing these short term effects in a group of volunteers who complained of such symptoms. The Essex study found that subjects were unable to tell whether they were being exposed to electromagnetic fields or not, and that sensitive subjects reported lower well-being independently of exposure. The principal investigator concluded "It is clear that sensitive individuals are suffering real symptoms and often have a poor quality of life. It is now important to determine what other factors could be causing these symptoms, so appropriate research studies and treatment strategies can be developed."

Experts consulted by France considered it was mandatory that main antenna axis not to be directly in front of a living place at a distance shorter than 100 metres. This recommendation was modified in 2003 to say that antennas located within a 100-metre radius of primary schools or childcare facilities should be better integrated into the cityscape and was not included in a 2005 expert report. The Agence française de sécurité sanitaire environnementale currently says that there is no demonstrated short term effect of electromagnetic fields on health, but that there are open questions for long term effects, and that it's easy to reduce exposure via technological improvements.