DePaul University Environmental Health and Safety > Ergonomics > Office Ergo >
- Bright lights shining on the display screen "wash out" images, making it difficult to clearly see your work. Straining to view objects on the screen can lead to eye fatigue.
- Place rows of lights parallel to your line of sight.
- Provide light diffusers so that desk tasks (writing, reading papers) can be performed while limiting direct brightness on the computer screen.
- Remove the middle bulbs of 4-bulb fluorescent light fixtures to reduce the brightness of the light to levels more compatible with computer tasks if diffusers or alternative light sources are not available. Note: a standard florescent light fixture on a nine-foot ceiling with four, 40-watt bulbs will produce approximately 50 foot-candles of light at the desktop level.
- Provide supplemental task/desk lighting to adequately illuminate writing and reading tasks while limiting brightness around monitors.
- Generally, for paper tasks and offices with CRT displays, office lighting should range between 20 to 50 foot-candles. If LCD monitors are in use, higher levels of light are usually needed for the same viewing tasks (up to 73 foot-candles).
- Bright light sources behind the display screen can create contrast problems, making it difficult to clearly see your work.
- Use blinds or drapes on windows to eliminate bright light. Blinds and furniture placement should be adjusted to allow light into the room, but not directly into your field of view. Note: vertical blinds work best for East/West facing windows and horizontal blinds for North/South facing windows.
- Use indirect or shielded lighting where possible and avoid intense or uneven lighting in your field of vision. Ensure that lamps have glare shields or shades to direct light away from your line of sight.
- Reorient the workstation so bright lights from open windows are at right angles with the computer screen.
- High contrast between light and dark areas of the computer screen, horizontal work surface, and surrounding areas can cause eye fatigue and headaches.
- For computer work, use well-distributed diffuse light. The advantage of diffuse lighting is that
- There are fewer hot spots (or glare surfaces) in the visual field, and
- The contrasts created by the shape of objects tend to be softer.
- Use light, matte colors and finishes on walls and ceilings to better reflect indirect lighting and reduce dark shadows and contrast.