ABSTRACT
CONTENTS 1.1 Introduction ......................................................................................................................... 1 1.2 Direct Current and ELF (0-3000 Hz) EM Fields ............................................................ 2
1.2.1 Naturally Occurring Fields ................................................................................... 2 1.2.2 Artificial DC and Power Frequency EM Fields in the Environment ............. 3
1.2.2.1 DC Fields................................................................................................... 3 1.2.2.2 High-Voltage AC Power Lines .............................................................. 4 1.2.2.3 Exposure in Homes ................................................................................. 8 1.2.2.4 Electrical Appliances ............................................................................... 11 1.2.2.5 ELF Fields in Occupational Settings..................................................... 14 1.2.2.6 Internal ELF Fields Induced by External
and Endogenous Fields........................................................................... 17 1.3 EM Fields at Intermediate and Radio Frequencies (3 kHz to 300 MHz) ................... 19
1.3.1 Electronic Article Surveillance.............................................................................. 19 1.3.2 EM Fields from Video Display Terminals.......................................................... 20 1.3.3 RF Transmissions.................................................................................................... 22
1.3.3.1 Shortwave Transmission......................................................................... 22 1.3.3.2 FM Radio and TV Transmission ........................................................... 22 1.3.3.3 Wireless Communication Systems (Base Stations,
Personal Wireless Devices Such as Cellular Telephones and Pagers).......................................................................... 23
1.3.4 RF EM Fields in Industrial Settings (RF Dielectric Heaters, Worker Exposure to Broadcast Systems)............................................................ 27 1.3.4.1 RF Sealers .................................................................................................. 27 1.3.4.2 Occupational Exposure from Broadcasting and Radars ................... 27 1.3.4.3 Exposure in Medical Applications........................................................ 28
1.4 Conclusion ........................................................................................................................... 29 References ..................................................................................................................................... 29
We encounter electromagnetic (EM) fields every day, both naturally occurring and man-made fields. This leads to exposure both in our homes as well as in our various
workplaces, and the intensity of the fields varies substantially with the situation. Quite high exposure can occur in some of our occupations as well as our personal activities, for instance, in trains, where the extremely low-frequency (ELF) magnetic field can reach rather high levels. The frequency of the fields we are exposed to covers a wide range, from slowly changing static fields to the gigahertz range.
