I heard an interesting story on the news last night. According to the CBC,
Some parents in the Barrie, Ont., area say their children are showing a host of symptoms, ranging from headaches to dizziness and nausea and even racing heart rates.
They believe the Wi-Fi setup in their kids’ elementary schools may be the problem.
In some cases, the parents feel far more certain that Wi-Fi is the cause than this phrase would lead you to believe. Some are threatening to pull their children out of school unless the Wi-Fi is turned off.
Of course you know my first reaction. Kids feeling sick at school but they feel fine at home on the weekends? No! How can that be?! Remembering myself as a child, I can certainly apply my own experience to understand the most obvious possible cause.
But could it be true?
The article reports,
Susan Clarke, a former research consultant to the Harvard School of Public Health, said Wi-Fi technology alters fundamental physiological functioning and can cause neurological and cardiac symptoms.
It sounds pretty serious, but I’m immediately sceptical because she doesn’t say “Wi-Fi signals” have these effects, but rather that “Wi-Fi technology” is the cause. I’m sceptical because 802.11g signals are 2.4 GHz and 802.11n signals are 2.4 GHz and 5 GHz. Microwave ovens typically use a frequency of 2.45 GHz. Mobile phones use various wireless technologies that take advantage of frequencies from 400 MHz to 3 GHz. So how can “Wi-Fi technology” be the cause when other signals using the same frequency are ignored? Are Wi-Fi signals so much stronger?
The FCC limits cell tower transmitter power so “maximum permissible exposure level of the general public (or exposure in “uncontrolled” environments) of about 580 microwatts per square centimetre (μW/cm2), as averaged over any thirty-minute period” for 869 MHz broadcasts. For 1850 – 1990 MHz broadcasts, the maximum exposure is 1000 μW/cm2, or one watt per square centimetre.
Cell phones themselves broadcast one or two watts in total, but with the exception of teenagers, we aren’t always on the phone.
So what about Wi-Fi signals? My own Wi-Fi firewall has a maximum transmission power of 17 dBm. This equals 0.05 watts of total broadcast power. So the maximum cell tower broadcast strength per square centimetre is twenty times the entire output of my Wi-Fi transmitter. Given that the cross-section of your head alone is more than 100 square centimetres, and there’s no way you’re going to absorb the entire output of a Wi-Fi transmitter, it’s likely that you’re absorbing far more microwave radiation from the nearby cell towers than from any number of Wi-Fi transmitters nearby. I’d venture that the difference is a magnitude or two, in many cases.
If signals around the 2.4 GHz range were the cause, the children would have had a far worse time with the signals from cell-towers in the area, but they didn’t. The kids experiencing problems were just fine until months after the Wi-Fi system was installed.
So until I hear something of more substance than a few dozen anecdotal stories about children who feel better on weekends than they do at school, I will remain sceptical. Wi-Fi being the cause simply doesn’t make sense, especially given the huge number of variables involved, both environmental and psychological.