6.4.2 Occupational Exposure
Occupational exposure occurs when adults encounter RF fields as part of their work under controlled conditions. An occupationally exposed worker is not simply any person who happens to be exposed while at work. The worker must be informed of the relevant RF hazards, trained in appropriate precautions, capable of recognizing potentially hazardous circumstances, and protected by a suitable workplace health and safety program.
Occupations with significant potential for RF exposure include the installation and maintenance of transmitting antennas, operation of broadcasting and radar facilities, work with industrial induction and dielectric heaters, and employment involving high-power communications or scientific equipment. Medical personnel may work near MRI systems, shortwave or microwave diathermy applicators, electrosurgical equipment, and RF or microwave ablation systems. Other examples include telecommunications riggers, military communications and radar personnel, broadcast engineers, industrial maintenance workers, and technicians working on energized RF systems.
Occupational exposure conditions vary widely. Using the field-region definitions established in Chapter 5, a worker may encounter a relatively uniform far-field wave from a distant antenna, a highly non-uniform reactive near field or radiating near field close to an RF source, currents induced in the body by lower-frequency electric or magnetic fields, or contact currents from a conductive object that has acquired RF energy. Pulsed radar, rotating antennas, intermittent communications traffic, and maintenance activities can also produce exposures that change rapidly with time. Assessment must therefore consider where the worker can stand, how long the task lasts, whether the equipment is transmitting, and whether normal shielding and interlocks remain in place.
Occupational exposure restrictions may be numerically higher than the corresponding general-public restrictions because they apply only under controlled conditions in which workers are trained and able to employ appropriate risk controls. This distinction does not mean that occupational exposure is expected to cause harm or that occupationally exposed workers are afforded less protection. Rather, informed workers can avoid hazardous areas, observe exclusion boundaries, reduce the time spent near an active source, use protective procedures, and arrange for transmitters to be isolated when necessary. People who do not meet the conditions required for classification as occupationally exposed remain subject to the general-public restrictions.