Make Lighting a Priority in Your Office.

A factor often overlooked in eyestrain problems is lighting and glare. Studies have shown that workers rate good lighting as the single most important aspect of the office environment. This is followed by air quality and comfortable chairs. Improper lighting is sometimes difficult to discern. You immediately recognize very low or very bright settings, but marginal lighting (enough light to see your work but maybe not see it well) may not be perceived as a problem.

Bright fluorescent lights over and behind the user cause reflections on the monitor face that make it difficult to read; this results in eyestrain and headaches. Often the monitor, and not the lighting, is blamed. With the monitor face being slightly convex, troublesome reflections can come from wide angles to the screen. Also, the common practice of tilting the monitor back increases the incidence of reflections from ceiling fixtures.

There are two glare problems to deal with, direct and indirect. Direct glare comes from line-of-sight light sources such as lights or windows. Since terminal users are looking forward instead of down at their desks, direct glare light sources are evident to them.

Indirect glare, or reflection, is probably the most common problem for terminal users. Indirect glare is caused by light from bright objects, such as light fixtures, reflecting from smooth or glossy surfaces. Monitors can have either a specular or a diffuse reflection. Specular reflections are mirror-like sharp images reflected from the monitor back into the users' faces. Diffuse reflections are reflections from light that penetrates the monitor's glass surface and is reflected off of the phosphor layer behind the glass. Since the phosphor is somewhat rough, no sharp or defined image appears brighter with the effect of washing out the image. The type of light fixtures used in an office is a factor in the amount of direct glare that is present. Overhead lighting fixtures (called luminaires) are a common source of direct glare. Light fixtures that are low and in the line of sight are glare-producing sources.

Often windows will be left unshielded to supplement ambient lighting or to offer a view. For the VDT user the sunshine just presents another glare source.

A comfortable light level is important for all office workers regardless of whether they work at a computer. A good balance is hard to achieve but can be done with planning.

Robert McNamera is a Office Standards Consultant based in San Jose.