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Induced current and SAR distributions for a worker model exposed to an RF dielectric heater under simulated workplace conditions.

Gandhi OP; Wu D; Chen Y; Conover DL
Health Phys 1997 Feb; 72(2):236-242
A human male model was used to assess the specific absorption rates (SARs) of the human body resulting from electromagnetic field leakage from a radio frequency dielectric heater. The finite difference time domain method was utilized in the calculations of SARs. The human model measured 1.34x1.34x1.4 centimeters (cm). In order to simulate working conditions, the dielectric heater was mounted on a wooden or metal frame, operated at 40.68 megahertz, and placed in a screen room with the dimensions 213x305x213cm. This volume was reduced by applying a uniform finer grid of points to the area of the room close to the human model and an expanding grid to the remaining areas of the room. Various worker postures were investigated. During the test runs, the dimensions of the screen room were decreased to 297x218x214cm. The z-directed electric field associated with the current in the block model led to the greatest error. The whole body averaged SAR for a worker standing in an unscreened area was 0.66 microwatts per kilogram (microW/kg), while the SARs for a worker standing in the screen room with a metal or wood frame were 0.92 and 1.13microW/kg, respectively. Higher SARs were determined for the upper body within the screen room than outside the screen room. Higher wrist SARs were obtained when the hands of the model were extended toward the heater than when the hands remained at the model's sides. The highest whole body averaged SAR, 2.03microW/kg, was calculated when the model sat on a wooden stool with both hands extended. A negligible difference was observed when the model was positioned on a metal stool instead, with an SAR of 2.02microW/kg. The authors conclude that the above method is useful for the calculation of SARs encountered by humans in the workplace.
NIOSH-Author; Electromagnetic-absorption; Absorption-rates; Biological-systems; Body-regions; Electromagnetic-fields; Worker-health; Electromagnetic-radiation; Simulation-methods; Whole-body-radiation; Author Keywords: radiation; nonionizing; dosimetry; electroniagnetic fields; radiofrequency
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Health Physics
Page last reviewed: November 6, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division