Is WiFi Safe in Schools?

In a word, yes. The state of the science is much more settled than a search of the internet would suggest. See Education Next for an excellent article about the topic of WiFi emissions. It was written by Dr. Ken Foster, professor emeritus of bioengineering at UPenn.

Over the years, we have helped schools, retailers and other enterprises evaluate the radio emissions in their facilities. Often, it begins with a question from a customer or employee about a source of radio waves on premises. There is a tendency to focus on the known (“I know there is a WiFi access point beaming microwaves at all of us while we are here…”) because the source is obvious and passersby have no control over it.

It can be unsettling to some knowing there is a device nearby that is beeping away like a Sputnik satellite all by itself. Yet, that feeble signal from the low-power access point on the ceiling produces a ripple in the sea of radio signals coursing through the space. This larger view of a multitude of radio waves in personal space may be even more unsettling for some, until it becomes apparent the total typically is still feeble.

Radio receivers are incredibly sensitive instruments. Background levels of natural radio frequency energy are quite low, leaving room for humanity to use the spectrum to communicate in many ways. A century ago, Edwin Howard Armstrong invented the tool that is still used today to separate one radio signal out of a sea of radio frequency energy – the superheterodyne process.

While our brains picture that burst of radio messages from the access point as a discrete signal, to the body it isn’t. Thanks to superheterodyning, each radio signal can be distinguished by a tuned receiver. Our bodies are poor radio receivers and they do not tune individual signals. Only when a source dominates the ambient radio spectrum at a particular spot does it dominate the energy that the body is exposed to. This is where measurements and computations of radio frequency emissions are most helpful. We measure individual signals, usually from high power sources, when there is a concern they are too high. We measure the broad spectrum (that sea of radio waves) to determine that the sum total of the emissions arriving there are not too high.

Devices like WiFi access points are low power emitters and must comply with safety standards by design. If you think there is too much radio energy in your environment, we can measure it.

[WiFi is a trademark of the WiFi Alliance]


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