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 range