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KMID : 0895419980080010146
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Journal of Korean Society of Occupational and Enviromental Hygiene
1998 Volume.8 No. 1 p.146 ~ p.154
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The Level of Exposure to Electromagnetic Fields Strength from VDT According to the Arrangement of Working Space VDT
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Abstract
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This study was designed to investigate the workers´ exposure level to electromagnetic field(EMF) in accordance with the VDT arrangement in the work place and distance from VDT. Author compared the exposure strength of EMF in line group(workers exposed to EMF from both front and back side) and in shielding group(workers exposed to EMF exclusively from front side). The levels of EMF at 30㎝ and 50㎝ from front side and at 30㎝ from back side of VDT were also measured.
The result were as follows:
1. Mean distance between a monitor and a worker in shielding group (47.7±8.7㎝) significantly longer than that in line group(44.3±7.2㎝). Strength of EMF in shielding group [1.3±0.7 V/m (electric field) and 18.2±11.5 mA/m (magnetic field) were lower than in line group [1.4±0.6 V/m and 26.6±11.6 mA/m, respectively] at the workers´ position.
2. The strength of EMF was decreased with the distance from VDT. The strength at 70 ㎝ from VDT was nearly the same as the background strength in the ordinary office rooms.
3. Working distance from 9 inch monitor was significantly shorter than that from 14 inch and wider sized monitors.
4. The strength of EMF in extremely low frequency spectrum of color monitors was higher then that of black and white monitor.
5. Metal coated filters significantly decreased the electric field strength of EMF when earth line was connected. Metallic shield was effectively decreased the EMF strength from VDT, but wooden shield was not.
From the above results, line type arrangement of VDT in the work place using metallic shield at the back side of VDT, and metal coated filter to monitor with application of earth line were recommended. It is also recommended to maintain workers position to be 60㎝ or more distance from monitor and 140㎝ or more between VDTs for minimizing workers´ exposure to EMF.
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