mesures des champs électromagnétiques, mesure de micro-ondes, danger santé micro-ondes
Radiofrequency exposure in the French general population: band, time, location and activity variability.
avril 1, 2010Publié par le
L’exposition aux radiofréquences dans la population générale française : la bande, heure, lieu et de la variabilité d’activité.
CNRS no. 6249 Chrono-Environment, Faculty of Medicine, Besançon, France. jean-francois.viel
Information on the exposure of individual persons to radiofrequency (RF) fields is scarce, although such data are crucial in order to develop a suitable exposure assessment method, and frame the hypothesis and design of future epidemiological studies. [..]
Summary statistics were calculated with the robust regression on order statistics method. Most of the time, recorded field strengths were not detectable with the exposure meter. Total field, cordless phones, WiFi-microwave, and FM transmitters stood apart with a proportion above the detection threshold of 46.6%, 17.2%, 14.1%, and 11.0%, respectively. The total field mean value was 0.201V/m*, higher in urban areas, during daytime, among adults, and when moving. When focusing on specific channels, the highest mean exposure resulted from FM sources (0.044V/m),[..]
Source: www.ncbi.nlm.nih.gov (Pubmed)
The problem starts with measuring every 13s and recording a mean value. This is close to meaningless when most sources, such as DECT, WiFi, GSM (mobile telecommunication) and so on are pulsed.
For instance DECT (base station of DECT cell phones) has a mean sending power of 2.1 mW if not used (radiating 24/7), if used about 10 mW, but the peak power, what is really transmitted is about 250 mW in sharp short spikes as the picture above shows.
Now measuring a calculated value such as the mean value is interesting, but doesn’t tell anything about the real exposure. Just as if you get in a speed control with your car, you wont be able to tell that you average speed during the last hour was well within the speed limitations.
We have done numerous measurements at different location. Exposure from FM transmitter is usually quite low, unless you are close to some FM radio station.
The meter used during the study was the EME SPY 120.
*(0.2 V/m are about 100 µW/m^2)