Health hazards of base stations

Another area of worry about effects on the population's health have been the radiation emitted by base stations (the antennas on the surface which communicate with the phones). This is because, in contrast to mobile handsets, it is emitted continuously and is more powerful at close quarters. On the other hand due to the attenuation of power with the square of distance, field intensities drop rapidly with distance away from the base of the antenna. Base station emissions must comply with ICNIRP guidelines of a maximum power density of 4.5 W/m² (450 microwatts/cm2) for 900 MHz and 9 W/m² (900 microwatts/cm2) for 1800 MHz.[56] These guidelines are set for heating, which is the only understood mechanism of electromagnetic fields on biological tissue. The ICNIRP guidelines are distrusted by some.[57]

Several surveys have found increases of symptoms depending upon proximity to electromagnetic sources such as mobile phone base stations. A 2002 survey study by Santini et al. in France found a variety of self-reported symptoms for people who reported that they were living within 300 metres (984 ft) of GSM cell towers in rural areas, or within 100 m (328 ft) of base stations in urban areas. Fatigue, headache, sleep disruption and loss of memory were among the symptoms reported.[58] Similar results have been obtained with GSM cell towers in Spain,[59] Egypt,[60] Poland[61] and Austria.[62] There are significant challenges in conducting studies of populations near base stations, especially in assessment of individual exposure.[63]

However, a study conducted at the University of Essex and another in Switzerland[64] concluded that mobile phone masts were unlikely to be causing these short term effects in a group of volunteers who complained of such symptoms.[65] The Essex study has been criticised as being skewed due to drop-outs of test subjects,[66] although these criticisms were answered by the authors.

As technology progresses and data demands have increased on the mobile network, towns and cities have seen the number of towers increase sharply, including 3G towers which work with larger bandwidths.[citation needed] Many measurements and experiments have shown that transmitter power levels are relatively low - in modern 2G antennas, in the range of 20 to 100 W, with the 3G towers causing less radiation than the already present 2G network. An average radiation power output of 3 W is used. The use of 'micro-cell geometries' (large numbers of transmitters in an area but with each individual transmitter running very low power) inside cities has decreased the amount of radiated power even further.[citation needed] The radiation exposure from these antennas, while generally low level, is continuous[citation needed].

Experts consulted by France consider it is mandatory that main antenna axis not to be directly in front of a living place at a distance shorter than 100 meters.[67] This recommendation was modified in 2003[68] 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.