Luminance In the Occupational Visual Field: An Evaluation of Office Workstations

Inappropriate lighting is one of the most common causes of visual disturbances in office workers. Visual demand can also lead to musculoskeletal problems such as tension neck syndrome. On the other hand, appropriate location of light sources and a suitable level of illumination can enhance visual capacity. A rational approach to visual risk assessment of tasks and workstations involves measurements in the occupational visual field, and in particular luminance measurement. We report a large scale photometric evaluation in six companies in northern and central Italy. Operator tasks were predominantly administrative with some computer aided design activity. Occupational visual field luminance ratios were found to be excessively high (>1:250 cd/m2) in 19% of workstations (n = 100), moderately high (1:100-1:250 cd/m2) in 20% and considered satisfactory (<1:100 cd/ m2) in 61%. Illuminance in the working plane ranged from 100-2500 lux and correlated poorly with luminance. Parameters were highly dependent on light fitting position and window location. The survey demonstrated shortcomings in lighting design and workstation layout, both from artificial and natural sources. It is recommended that photometric assessment incorporate both luminance (occupational visual field) and illuminance measurements