The forgotten ergonomic

When we hear “ergonomics” around the office, lab, or factory floor, we think of proper workstation height, good computer screen and keyboard placement, and correct seating. But there’s one other ergonomic variable that’s often left to chance: proper lighting, a factor that’s equally important for enhancing worker comfort and performance.

We may type on ergonomic keyboards while seated on an ergonomically correct chair, but also may be working beneath harsh fluorescent lighting or perhaps in a dimly-lit room. Failing to properly match lighting to the task at hand can lead to Computer Vision Syndrome (CVS) with symptoms such as eye strain, blurred vision, headaches, neck pain, itchy eyes, and trouble sleeping. Improper lighting, which includes too bright, too dark, too contrasty, or the wrong color temperature, may also lead to higher error rates, reduced mental alertness, and even reduced morale caused by working in an under-lit “gloomy” atmosphere or one with distracting glare.

Creating a correctly lit environment to ensure good health and productivity requires addressing three lighting variables:

  • Placement
  • Intensity and contrast
  • Color temperature

Getting Light in the Right Places

Windows or a bright light source reflected on a computer screen are major contributors to eye strain. Our eyes are especially sensitive to glare from light sources in our peripheral vision. Harsh, usually fluorescent, overhead lighting often creates the same problems. Indirect lighting fixtures that bounce light off walls and/or ceilings are ergonomically preferable to traditional down lighting since they eliminate a big source of glare. Things get more complicated when there are multiple light sources as shown in the illustration.

Whatever the light source, it’s important to make sure the screen or the task does not directly face into the window or a bright light source. A basic rule for computer users: never place the monitor where light bounces off of the screen. In situations where either lights or the screen can’t be moved, a monitor glare screen may be useful.

There are also detail-oriented tasks such as reading printed material, preparing lab specimens, or assembling electronic modules. All these need brighter light to illuminate the task but not shining in the eyes. An adjustable “task light” can solve this problem. Adjustable task lighting is easy to add to a Workplace workstation using our Adjustable Lamp Bracket.

Intensity and Contrast

Ambient lighting that’s too dim causes squinting and straining, while lights that are too bright wash out screens making them difficult to read. In a dim room supplemental lighting such as an incandescent table lamp on the worksurface can help. In a room that’s too brightly lit by fluorescents it may help to remove one or two tubes from the fixture.

Having too much contrast—the difference between lightest and darkest areas—can be a problem, too. When our eyes move from light-to-dark and back again such as using a computer in a dark room, the irises of our eyes contract and expand frequently causing eye fatigue and strain. Fortunately, there are many ways to avoid extreme light-dark contrasts. When working at a computer, overall light intensity of the screen and ambient lighting should be about the same level. If working in a sunlit room, it’s helpful to have an app that automatically adjusts screen brightness, dimming the screen as the room turns darker in order to reduce contrast.

Color Temperature

The lighting variable that’s probably least understood is color temperature, the range of colors of light from red to blue, measured in degrees Kelvin (K), ranging from about 2400K for “warm” or yellowish incandescent lights to 5000K for “cool” fluorescent lights and upwards to 6500K for a typical LCD monitor.[1] (By comparison, sunlight can range anywhere from 5000K on the horizon to 15,000K directly overhead on a clear day.) It’s a well-established fact that the bluish light of “screens” interferes with our circadian rhythm, which is why sleep experts recommend against taking mobile devices like smartphones to bed with you. Yellow light at the lower (warmer) end of color temperature spectrum is easier on the eyes. However, on the factory floor, in the lab, or in a windowless space, a cooler color temperature closer to daylight may provide better overall lighting for tasks involving detail work.

This is where modern LED lighting with adjustable color temperature between about 2800K (warm) to 6000k (cool) can come to the rescue. In addition to its inherent energy savings, newer buildings are being designed with direct and indirect lighting whose intensity and color temperature can be controlled to whatever task is being performed.

Lighting at the Workstation

There’s a wide variety of lighting options for Workplace workstations, ranging from the Adjustable Lamp Bracket noted above to the tilting Light Suspension System which accommodates a variety of fluorescent and LED lighting fixtures. Under shelf lighting is also available to ensure even lighting of the work surface where overtable shelves are installed.

 


[1] Notice that the higher the color temperature the “cooler” or bluer the light. Low color temperature is reddish or “warmer.” Color temperature is described opposite to our cultural stereotype that tends to think of red as warmer than blue.