Comparison of methods used for measuring the electrostatic field of video display terminals.

The electrostatic field of video display terminal (VDT) operators was measured with different methods. Using the Wilson plate method the field strength at different locations at the face of three human subjects working with a VDT was determined. The strongest fields were found at protruding facial features. Measurements were also made with a measuring instrument known as a field mill. Comparative measurements were made with the field mill as such and combined with a metal plate or a hemisphere. The measured field strength was highly dependent on the method of measurement. A conducting hemisphere (diameter 0.20 m), used in combination with the field mill, was found to be a useful model of the human head in electrostatic measurements.