Two VDTs were tested to determine their impact on the DC electrical environment. Characteristics of the DC environment were measured — ion concentration, ion current density and DC electric field. Measures of particulate levels, temperature and humidity were included since these factors are known to influence the DC environment. Ion concentrations, especially negative ion concentrations, varied as a function of distance from the VDTs, with the lowest values observed in the immediate vicinity of the VDTs for both models tested. This effect was slight and within the range of expected indoor values for ion concentrations. DC electric fields were generally found to be higher during VDT operation compared to controls, although they were within the same order of magnitude as commonly experienced fields due to charges on materials (e.g. clothing, carpet) indoors. Particulate levels were not observed to be altered by VDT operation.