Unstrung has been asking around recently to find out if there are any potential health risks associated with the growing use of wireless LAN technology. We wondered if the growing use of 802.11b technology -- in our homes, cafés, and other public areas -- with the resultant increase in radio traffic all around us should be a cause for concern.

The answer seems to be... Maybe -- if you are one of the growing band of people who use home-made equipment to increase the range of 802.11b hotspots.

Understandably, in the wider world, there isn't the same level of concern about the radiation emissions from relatively low-power WLAN kit as there is about, say, living next to a cellular tower. And apparently, as long as you're using standard-issue commercial wireless LAN kit, the emission levels are tightly controlled by the Federal Communications Commission (FCC) in the U.S. and other regulatory bodies worldwide.

However, some of people working outside of the strictly commercial WLAN market -- boosting the range of their local wireless community sites with Pringle can antennas, for instance -- could potentially be taking a risk, according to David Sifry, CTO at open-source WLAN mavens, Sputnik Inc."I'm not a doctor, nor do I play one on TV," he writes in an email reply to Unstrung. "So please take this for what it is worth -- one engineer's understanding of the current issues, and some extrapolation of current physical research into the 2.4GHz spectrum.

"Current FCC regulations limit power output to 1 Watt EIRP (Effective Isotropic Radiated Power) for 802.11b (2.4GHz) devices. Most cards are 30 milliwatt, and there are a few 100mW and 200mW cards out there. Compare this with microwave ovens, which can emit 500 to 700 Watts to heat up your dinner. Of course, microwave ovens are shielded, but even a small amount of leakage would emit more radiation than these 802.11 devices."

However, Sifry fears that some of the more outré methods being used to boost the range of WLAN systems could prove to be hazardous: "Of course, if you illegally crank up the power or narrow the beam [exactly as the Pringles can antenna does], the EIRP goes way up, so there are potential health threats associated with using illegal equipment."

Now, these kinds of booster devices tend to be placed on rooftops and thus generally away from people, in order to get the best line-of-sight access. So it is hard to gauge exactly how much of a risk there is from such signal amplification. And common sense suggests that you don't walk in front of your home-made antenna if you are really trying to crank up the range of your 802.11b system (Unstrung health tip number one).

Despite the low emissions of commercial WLAN equipment, Jack Gold, VP of the mobile and pervasive computing group at Meta Group sums up just how much we don't know about the effects of widespread use of wireless technology.

"I'm not sure anyone knows the long-term effect of walking around in lots of radio fields… I think it may take years before we have proof one way or the other about the effects," he says. "Of course, I am not a medical researcher, so I am not able to give a medical opinion -- but from all that I've read, the jury is still out on this."

— Dan Jones, Senior Editor, Unstrung
http://www.unstrung.com