Two schools in UK turn off Wi-Fi: A few scattered complaints resulted in a school in England and another in Wales turning off their Wi-Fi networks. The lack of evidence of harm appears to be no reason to not disable the networks. One teacher reported ill health effects, but it doesn't appear that any effort was taken--it's not cited--to determine whether those effects resulted from something else. It's vanishingly unlikely that the symptoms this teacher had could be caused by microwave radiation of any kind, even at extremely high doses, and not effect those nearby. Even if this person has a unique constitution, the prevalence of Wi-Fi and similar, much more highly powered networks would lead us to expect thousands to tens of thousands of cases being reported daily, too.
The Health Editor of The Times (UK) notes that "it is impossible to prove anything safe" and that "The best that can be hoped for is no evidence of risk: evidence of no risk is asking the impossible." He points out that the extremely low levels of signal strength pouring out of Wi-Fi networks makes it unlikely to be a causal agent, even if you accept that mobile phones--which spit out much higher wattages--is a health risk. The Inquirer jibes, "if the mummies and daddies are worried about piddly little wi-fi systems, they'd better start thinking about WiMAX beams which they won't be able to avoid unless they kit their kids out with tin foil hats."
(The Times has already published letters in response to the column, including two that state bluntly that Wi-Fi makes people sick. This is easily testable in blind studies. Is anyone doing this work?)
Meanwhile, a Welsh MP and a Welsh paper spread fear further by reporting without attribution that the technology has been banned in schools in Canada." One school. One school is Canada did so based on non-existent studies.
Am I saying there's no chance that there's any potential risk of any sort from being close to networks that use Wi-Fi for communication? No. But I am pointing to both Occam's Razor and the Law of Very Large Numbers. If you have enough people exposed to the same technology, you should have large numbers of similar outcomes with no other reasonable explanation, including cancer clusters, sick days, and so forth. Sure, some health effects can take decades to appear. But the particular sort of problems cited, such as shortness of breath, rashes, and dizziness are rather obvious.