Lighting evaluation in the office environment

Introduction
Lighting, both natural and artificial, is one of the most important environmental sources of visual disorders and disturbances in the work places (occupational asthenopia). Moreover, fine work, particularly computer tasks, is becoming more and more widespread, contributing to increase the visual work load as well as luminance ratios in the “occupational visual field”.

Methods
10 workstations were studied, located in two administrative offices. Each workstation was used by one single operator at time. Photometry evaluation was carried out by measuring both illuminance and luminance. As to luminance, we applied the method proposed by Piccoli B., Soci G., Zambelli P., Pisaniello D. (Photometry in the workplace: a rationale for a new method. Ann. Occup. Hyg., Vol. 48, No. 1, pp. 29–38, 2004).

Results
Luminance ratios detected in the operators' occupational visual field were very high (>1:250) in 3 workstations (33%), moderately high (1:100-1:250) in 5 workstations (50%), and adequate (<1:100) in 2 workstations (22%). Illuminance on the working plane, ranging from 80 lux to 2150 lux, was poorly unrelated with luminances.

Discussion
The measurement of luminance in the “occupational visual field” appears an effective approach when “lighting risk assessment” needs to be carried out, with specific reference to the operator’s subjectivity.
The measurement of illuminance is appropriate for lighting control strategies (energy saving, minimum maintained levels, daylight factor component, esthetic applications, etc.).