I appreciate that the inverse square law would mean laptops located farther away are going to contribute insignficant amount of radiation to my incremental exposure. Instead of the 300-500 times incremental exposure, I might only experience a triple or quadruple amount of exposure mostly attributed to the laptops in my immediate vicinity.

These levels are probably still benign, but do we really know where "benign level" begins and stops?

[Editor's note: Not 3 or 4 times as much: Even if you're surrounding by 8 laptops as the center of a square, you're probably getting no more than 20 or 30 percent higher emission exposure than your own device. Inverse square means signal strength drops very rapidly. To get the maximum signal exposure, everyone would have to be streaming at full speed all around you, too. Wi-Fi is burst just like Internet access in general is bursty: mostly empty with moments of usage.

Empirically, lots is known: the FCC and other groups have been studying exposure to microwave radiation (electromagnetic radiation in the range that covers all radio communication) for decades. That doesn't mean there aren't emergent properties, nor special cases because of the closeness of newer emitters to our laps or heads.

Generally, though, you can predict based on the amount of energy in a signal (through measurement or theory) how much excitation will be provoked and by what kinds of molecules. --gf]

A microwave oven's radiation is well contained, even though some leakage exists but it's not on 24 hours a day and I don't have to stand near it when it is on.

A chemistry professor at U. of Oregon- Paul C. Engelking, also raised concerns about wi-fi, but for other reasons like students surfing the net while they should be paying attention in class. He caught my attention when he pointed out a possible scenario in which a large lecture hall filled with 300-500 laptops connecting to the wi-fi. With 100 mW output from each laptop, the aggregate radiated power can add up quickly to range betwen 30 and 50 W. The radiation from my own laptop, or that of the wi-fi access point would probably not bother me as much as the combined radiation from the other possible 459 in a confined space like a lecture hall.

[Editor's note: That's not correct. Hundreds of laptops are each their own radiator and each have significant signal dropoff with the inverse square of the distance from the source. So having 100 30 mW radiators isn't like having 30 W of radiation in a space, even with reflection.--gf]

Don't forget about televisions, radios, wireless keyboards/mice, etc. Any CRT monitor. There are all sorts of emissions in our every day life. I mentioned cell towers in my post too, but I'm a lot more cynical than you, Glenn. *laugh*

Take care.