The widespread use of cellular phones has led to the placement of cellular phone towers in many communities. These towers, also called "base stations," consist of radios, computerized switching equipment, and antennas that receive and transmit radiofrequency (RF) signals.
When a person makes a cellular phone call, a signal is sent from the phone抯 antenna to the base station antenna. The base station responds to this signal by assigning it an available radiofrequency channel. Transmission and reception of these radio signals transfer the voice information to the base station. Next, the voice signals are sent to a switching center, which transfers the call to its destination. For additional information on the phones themselves, please see the American Cancer Society document, "Cellular Phones."
Cellular phone towers are usually mounted either on top or on the side of existing structures, such as trees, water tanks, or tall buildings. The antennas need to be located high enough so they can adequately cover the area. Base stations usually range in height from 150-270 feet.
Cellular phones operate at the radiofrequency (RF) part of the electromagnetic spectrum. This is non-ionizing radiation. Other examples of the non-ionizing part of the electromagnetic spectrum include AM and FM radio waves, microwaves, and infrared waves from heat lamps. Unlike x-rays and gamma rays (which are examples of ionizing radiation), radio waves have too little energy to break the bonds that hold molecules (such as DNA) in cells together. Similarly, since RF of this frequency contains relatively low energy, it does not enter tissues. At very high levels of exposure, RF can cause warming of tissues, much as a heat lamp does. The wavelength of cell phone waves is about one foot and the frequency is approximately 800 to 900 MHz, although newer models may use higher frequencies up to 2,200 MHz.
