Appendix C
Exposure levels

[An extract from Wi-fi in the classroom: health advice to schools, a report prepared by Michael Bevington of Stowe School: LINK ]

1 Health studies

Health studies on specifically wi-fi radiation have not yet been made, but the pulsed microwaves used are similar to those for mobile phones and seem to have similar health effects to other forms of EMR [electromagnetic radiation]. These have been studied for the general population but not often specifically as regards children. The Schwarzenburg study (1995) showed among the general population health problems with concentration, fatigue, sleep, depression and cardiovascular conditions, all typical symptoms of sensitivity to EMR, at EMR exposures down to 0.05 V/m [volts per metre]. The Oberfranken study (2005) showed typical sensitivity symptoms in 30% of people at under 0.06 V/m, and 95% in the range 0.2 – 0.6 V/m. The Naila study (2004) showed that cancer rates are trebled within 400 metres of a mobile phone mast at 0.6 V/m in a dose-response relationship after 5 years’ exposure, and the Netanya study (2004) showed female cancers increased ten times within 350 metres of a mast.

2 Radiation intensity

A laptop (100 or 200 mW wLAN cards) can emit radiation with electric fields of 4.0 - 6.0 V/m at its transmitter, 1.1 - 4.9 V/m at 50 cm, a typical sitting distance, and 0.7 - 2.8 V/m at 1 m. In a classroom with 30 laptops transmitting, the electric field could be greater. In comparison, mobile phones can reduce their emissions during a call down to about 0.0002 V/m. Even so, some studies suggest that mobile phone use can determine the side of the head in which tumours can appear after 10 years.

3 Sensitivity

Much of the damage from low levels of EMR to human cell tissue appears to be cumulative and thus the symptoms may not be felt for many years. A child’s cell tissues in the head are said to absorb 60% more radiation from a mobile phone than an adult’s. Wi-fi radiation affects the whole body surface and not just the head. Since the development of digital transmissions, the number of people becoming sensitised to EMR has grown rapidly. Although it is likely that all human beings are subconsciously sensitive, in that the existing electrical fields within their cell tissues are influenced by external fields, most humans are not yet aware of how the typical sensitivity symptoms relate to exposure from EMR. In Sweden about 3.1% of the population may suffer from Electro-Hyper-Sensitivity.

4 Guidelines

a) Thermal (heating)
UK government guidelines on limits (41 V/m at 2.4 GHz) are only to avoid heating human tissue more than 1 degree, based on the Specific Energy Absorption Rate (SAR).

b) Non- thermal (below heating levels)
Salzburg sets the non-thermal indoor limit at 0.02 V/m (peak pulse). This is to help protect people from non-thermal or bioelectromagnetic effects of EMR, such as DNA damage, cancer growth, and fertility and neurological problems. Salzburg’s Public Health Department warns against wireless systems and DECT phones in schools and nurseries. The UK does not have any non-thermal guidelines.

c) Peak pulse measurements
Many scientists think the peak level of the radiation pulses is particularly dangerous. For wLAN (wi-fi), the difference between the base and peak levels is 1,000 times (DECT phones: 100 times) of the power flux density. Therefore measuring the average level or the root mean square (RMS) is inadequate.

5 Measurements at a Norwich school on a Panorama programme (BBC1, 21.5.07)

(a) 100 m from the phone mast: peak readings of 0.7 V/m
(b) 50 cm from the laptop: peak readings of 1.7 V/m


Schwarzenburg study, Switzerland: Abelin, T. et al., ‘Study of health effects of the Shortwave Transmitter Station of Schwarzenburg, Berne, Switzerland,’ University of Berne, Institute for Social and Preventative Medicine, Bundesamt für Energiewirtschaft Schriftenreihe Studie, 56, 1995.

Oberfranken study, Germany: Bamberg doctors’ Report and Appeal, based on records of 357 patients, 2005.

Naila study, Germany: Eger, H. et al., ‘The Influence of Being Physically Near to a Cell Phone Transmission Mast on the Incidence of Cancer’, Umwelt·Medizin·Gesellschaft, 17.4, 2004.

Netanya study, Israel: Wolf, D. & Wolf, D., ‘Increased Incidence of Cancer near a Cell-Phone Transmitter Station’, International Journal of Cancer Prevention, 1(2), April 2004.

Some other studies:

La ora, Mercia, Spain: Navarro, E. A., et al., ‘The microwave syndrome: a preliminary study in Spain’, Electromagnetic Biology & Medicine, 22 (2 & 3), 2003, 161-169;

Oberfeld, G., et al., ‘The microwave syndrome—Further Aspects of a Spanish Study’, International Conference Proceedings, Greece, 2004.

French study: Santini, ‘Study of the health of people living in the vicinity of mobile phone base stations,’ Pathologie Biologie (Paris), 50 (2002), 369-373.

Skrunda study, Latvia: Kolodynski, A. & Kolodynska, V., ‘Motor and psychological functions of school children living in the area of the Skrunda Radio Location Station in Latvia,’ The Science of the Total Environment, 180, 88-93, Elsevier, 1996.

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