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An Investigation of Electric and Magnetic Fields and Operator Exposure Produced by VDTs: NIOSH VDT Epidemiology Study (Final Report).

NIOSH 1990 Sep:290 pages
Electric and magnetic field emissions of video display terminals (VDTs), both radiofrequency (RF) and extremely-low frequency (ELF), were investigated at AT and T and Bellsouth telephone operator facilities. The purpose of this study was to assess the strength of the electric and magnetic fields produced by the different types of displays to which workers could have been exposed. A total of 96 VDTs, selected at random, and located in nine cities was studied. VDTs produced by Computer Console, Inc. (CCI) and International Business Machines (IBM) were tested. Both types of VDTs produced essentially the same horizontal deflection frequency; CCI units produced a nominal frequency of 15 kilohertz (kHz) and IBM units produced a nominal frequency of 16kHz. Nominal vertical deflection frequencies were 45Hz for the CCI displays and 60Hz for the IBM units. The very low frequency (VLF) RF electric and magnetic field strengths at 30 centimeters from the VDT screens fell predominantly in the range of 1.3 to 8.5 volts per meter and 4.0 to 161 milliamperes per meter, respectively. Measurements of field strengths in the VLF range for non VDT displays (nixie glow tube and light emitting diode) were significantly less. The strength of the fields decreased extremely rapidly with increasing distance from the screen. The authors conclude that VDTs represent a relatively minor contribution to everyday exposure to such fields in the life of the worker.
NIOSH-Contract; Computer-equipment; Office-workers; Data-processing; Keyboard-operators; Electrical-fields; Electromagnetic-fields; Nonionizing-radiation; Video-display-terminals;
Publication Date
Document Type
Final Contract Report;
Fiscal Year
NTIS Accession No.
NTIS Price
Identifying No.
Source Name
Richard Tell Associates, Inc., Las Vegas, Nevada, NIOSH Purchase Order 90-37729, 290 pages, 82 references
Page last reviewed: September 4, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division