Investigations on workers' exposure to strong electromagnetic fields on the basis of contact and induced currents

The aim of this research task was to assess workers' exposure to strong electromagnetic fields with the use of measurements of contact and induced currents, to develop principles of using those measurements to ensure workers' safety and health in the workplace, and to present them in a guide.Contact and induced currents, and the strength of electric and magnetic fields were measured. Characteristics of the conditions of workers' exposure to the electromagnetic field were investigated at over 300 typical workplaces.Investigations were conducted in radio broadcasting centres which use medium-, short- and ultrashort-wave equipment. Significant for workers secondary hazards was revealed. Those hazards were caused by metal structures in the vicinity of antennas, as a result of the flow of current when workers touch those structures.It was shown that in the process of occupational risk assessment it is especially important to include- an assessment of induced current in the workplace of operators of physicotherapeutic diathermy, electrosurgery devices and dielectric heaters,- an assessment of contact current in the workplace in the vicinity of medium-, short- and ultrashort-wave radio transmitters.Model setups for phantom measurements of contact current in the 10 kHz - 10 MHz frequency range were developed, constructed and tested. They contain RC circuits that model the human body's impendence when a finger or a hand touches a secondary source of an electromagnetic field.A concept model of an interim solution to the problem of equipment for phantom measurements of induced current was also developed.The conducted measurements and gathered practical experience were used in the development of a guide on the principles of using measurements of contact and induced currents for the purposes of occupational safety and health (OSH).