Work with visual display units: Long-term health effects of high and downward line-of-sight in ordinary office environments

This study investigated the long-term effects of vertical monitor placement in 150 ordinary offices workers. Random assignment was used in creating a high line-of-sight (HLS) group (n=75)(n=75) and a downward line-of-sight (DLS) (n=75)(n=75) group. The line-of-sight to the midpoint of the screen was 15° below horizontal for the HLS-group and 30° for the DLS-group. Measurements were taken at set-up and again 12 months later. Significant differences, favouring the DLS-group compared to HLS-group, were found for subjective symptoms, oculomotor capacity, and self-reported sick leave. The DLS-group exhibited flexion of both the neck and back about 5° more than the HLS-group. No differences were found for work-related diagnoses, traditional clinical measures, or electromyographic activity. The results correspond with previous laboratory findings and give additional empirical support from natural work environments to the beneficial effect of DLS in visual display unit (VDU) work.Relevance for industryVDUs are widely used in industry. Vertical monitor placement is an important factor in the discussion about negative health effects associated with VDUs. Knowledge about health effects of different line-of-sight in ordinary offices and the concordance of results between field and experimental settings has importance for future guidelines.