Introduction to Ergonomics

Lighting

An environment with high illumination washes out images on a video-display screen because a VDT produces its own illumination and contrast. For this reason, VDT work areas should have lower light levels than standard office areas. For these areas, illumination ranges should be 30-50 footcandles for screen viewing and 50-70 footcandles for reading printed documents. Adjustable lamps may be needed to provide supplemental light for reading printed documents. To control direct-glare and reflected-glare sources, the walls, furniture, and other equipment located near a VDT should not have highly-reflective finishes. To reduce glare, walls can be painted non-reflective, subdued colors.

Windows should have adjustable vertical blinds or drapes, and the VDT work area should be located away from and at right angles to windows. During bright, sunlit periods, the window must be draped, shut, or shaded to prevent screen glare and eye fatigue. Employees must be able to adjust window blinds as needed.

Light fixtures should be equipped with diffusers, cube louvers, or parabolic louvers when located near VDTs. Recessed or indirect lighting systems can eliminate glare and reflections but are not suitable for all workplaces. To reduce glare and reflection from overhead lights, place the VDT work areas between rows of overhead lights.

Screen glare filters should be used as a last resort, as they can contribute to blurring and poor contrast of screen characters. Using screen filters is a supplementary solution and not a substitute for proper lighting as described above. The American Optometric Association has compiled results of screen glare filter tests. If screen filters are used, a supplementary visor hood should be considered.