Philadelphia, the city of brotherly love has it. Many in San Francisco want it...
Wireless broadband Internet access (wifi) seems too good to be true. At relatively low cost, anyone can get on the Internet anywhere in a city. All the city needs to do is install wifi antennas.
An argument in favor of citywide wifi is that it will reduce the digital divide: the poorer you are, the more limited your access to the Internet and its information resources. Cities like Philadelphia and San Francisco are actively trying to close the digital divide. One option is wifi.
Yet in weighing the options, virtually nothing is heard about the potential health risks. Saturating an entire city with wifi adds to the existing burden of nonionizing radiation. That burden, called electrosmog by some, consists of long-term exposure to low-level concentrations of nonionizing radiation from familiar sources like radio and TV signals, electronic and electrical devices, and the ubiquitous cell phone.
Wireless Internet Access
Local area networks (LANs) link computers, printers, modems, and other devices. Traditional LANs make the links physically using wire cable. Messages between computers and the other devices on the network are managed by a device called a router.
A wireless LAN does away with the wire cable by using a router that transmits and receives radio signals. To use a wired LAN, you have to plug the computer or other device into a wall socket. A wire leads from the socket to the router, which manages signal traffic between the devices on the network.
With a wireless LAN, each device on the network is built so that it can send a signal to the router and receive signals back. Wireless routers typically have a range of a hundred to several hundred feet. The range can be increased by adding a booster that increases the signal strength.
As with all radio signals, the closer you are to the transmitter (the router) the stronger the signal. Cell phones work on the same principle. The difference is that cell phones work at a different frequency and put out a stronger signal than wireless LANs.
Radio Frequencies
Cell phones operate at frequencies in the 3 to 30 GHz range, similar to microwave ovens. Wireless LANs operate at one tenth of that range0.3 to 3 GHz, the range of UHF television broadcasts. GHz stands for gigaHertz, a standard measure of radio frequency radiation (RFR)electromagnetic radiation created by sending an alternating electrical current through an antenna. The higher the GHz, the faster the current alternates.
frequency by itself does not measure the potential effect of RFR. As you would guess, the strength of the signal also matters. The strength of a signal is measured in watts, a standard measure of electrical energy. For example, a 100 watt light bulb is brighter because it puts out more energy than a 60 watt bulb.
Think of the effect of waves at the beach: small waves far apart (low strength, low frequency) versus large wave close together (high strength, high frequency). The former is likely to have less of an effect than the latter.
The exposure to RFR is measured using SARspecific absorption rate. SAR is expressed either in milliwatts/kilogram (mW/kg) of body weight or milliwatts/cubic centimeter (mW/cm2) of exposed body area: the size of the wave and how much of your body it strikes.
Health Risks
wifi enthusiasts dismiss health risk concerns because the power output and SAR exposure is significantly below the minimum standard set for cell phones. But cell phone standards are set for the short term exposure of a cell phone in use pressed to your head. In addition, the standards are set based on the thermal (heating) effect of the radiation.
Nonthermal effects of cell phones are documented at exposures below the current US standards, including
- memory loss,
- sleep disruption,
- slowed motor skills and reaction time,
- decreased immune function,
- spatial disorientation and dizziness,
- headaches,
- lowered sperm count,
- increased blood pressure and pulse,
- DNA breakage and reduced DNA repair capacity, and
- cell proliferation.
A second problem is that cell phone exposure is intermittent, whereas wifi exposure is constant. A more accurate comparison is to the effect of cell phone broadcast antennas. These antennas send and receive radio frequency signals constantly.
The signal strength from an antenna is comparable to a cell phone only at very close range. The exposure is not a cell phones brief blast but a persistent bath of low- strength RFR. In addition to the health effects documented for cell phone use, exposure to cell phone antennas include
- increased blood pressure and pulse,
- sleep disruption,
- emotional effects such as increased depression and irritability,
- memory loss and mental fog,
- fatique and vertigo, and
- increased cancer risk.
Because of these effects, the International Association of Fire Fighters (AFL-CIO) decided in 2004 that they will not permit cell phone antennas on fire houses.
RFR Hypersensitivity
much of the discussion of RFR health effects is framed as a concern with people who are hypersensitive. Hypersensitivity is the technical term for allergies and similar immune system overreactions. But instead of pollen, RFR hypersensitivity is a reaction to nonionizing radiation. It seems that an unlucky few are affected while the rest of us are off the hook.
Research by Olle Johansson and rjan Halberg of the Karolinska Institute, Stockholm suggests otherwise. They looked at the incidence of cancer in Europe and the US and found a striking association between the increase in certain cancers during the 20th Century and exposure RFR as measured by radio and TV broadcasts.
What the hypersensitive really represent is one extreme in a complex landscape of effects and risks. Just like any other environmental stressor, RFR will affect some people more than others. And as with other environmental stressors, the greater the overall burden, the greater the risk of becoming one of the the unlucky few.
Wireless LANs add to the existing burden of RFR. Just as burning more fossil fuels adds more smog, adding more RFR adds more electrosmog. You dont have to expose your home or your city to the increased burden created by wifi. Theres a viable alternative: a wired LAN. The hype might make it seem less convenient and more expensive. But whats a good nights sleep worth? Or reducing your risk of cancer?
Resources
International Association of Fire Fighters. 2004. Position on the Health Effects from Radio Frequency/Microwave (RF/MW) Radiation in Fire Department facilities from base Stations for Antennas and Towers for the Conduction of Cell Phone Transmissions. Access at http://www.iaff.org/safe/content/celltower/ celltowerfinal.htm.
Johansson, Olle and Doug Loranger. 2005. Electrosmog. Your Own Health And Fitness. Broadcast November 29, 2005. http://yourownhealthandfitness.org/ radiation.html.
Sage, Cindy. 2005. Comment on San Francisco TechConnect Community Wireless broadband Initiative. Sage Associates: September 2005.
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