Safety Office, Commissary Building
University of Waterloo
200 University Avenue West
Waterloo, Ontario, Canada N2L 3G1
Phone 519 888 4567 Ext. 33587
Fax 519 886 8082
Email: safety@uwaterloo.ca
Many of us rely heavily on computers to help us perform our work - for some, dedicated computer work is necessary, while others multi-task throughout the day. No two people are the same, and ergonomics strives to fit the task to the person doing it.
The office ergonomics guide is intended to guide you in a self-assessment of the ergonomic design of your computer workstation. These helpful tips can show you how to identify and correct ergonomic problems to prevent repetitive strain injury, eyestrain, fatigue and discomfort.
To get started, move through the components of your workstation - evaluate and adjust each one in order, according to the guidelines.
Engineering controls
Task chair
An ergonomic chair will not function as designed unless you know how to operate the adjustable features correctly. To adjust your task chair, follow the steps:
Seat height
Sit as far back in the chair as possible
Adjust height till:
- Feet are flat on the floor
- Thighs are parallel to the floor, hips and knees at 90 degrees.
Seat pan
Sit as far back in the chair as possible
Adjust Seat pan till:
- There are two-three finger width of space between the back of your knee and the edge of the seat
- The seat pan tilt angle should also be parallel to the floor
Backrest
Sit as far back in the chair as possible
Adjust backrest till:
- Backrest height or lumbar support fits into the curve in your lower back.
- Backrest angle should promote hip angle of 90-110 degrees (have someone else look at you from the side).
Armrest
Sit as far back in the chair as possible
Adjust armrest till:
- achieve an angle of 90-100 degree at the elbow, while your shoulders are down and relaxed.
Keyboard tray
There are numerous keyboard and mouse configurations and models available, however it is important to correctly position these tools to prevent overuse injuries.
Sit as far back in the chair as possible
Adjust keyboard tray till:
- Sit close to the keyboard and mouse so that your upper arms hang in a relaxed position.
- Height of the keyboard platform (or chair if there is not an adjustable platform), promotes relaxed shoulders and elbow angle is 90 degrees or slightly greater.
- Angle the keyboard platform slightly downward in a negative tilt, if able. This will help to keep your wrists straight.
Body position
Center yourself so that you are aligned with both the keyboard and mouse, depending on what is most frequently used. Position the mouse as close as possible to the keyboard to avoid rotating the shoulder.
Do not put the mouse where you must stretch to the desk or out to the side of a keyboard to reach it.
If keyboard prevents you from bringing the mouse closer, consider a compact keyboard
Your wrist should be straight while mousing, not angled toward your thumb or little finger.
Move the mouse from the elbow, rather than from the wrist down.
Monitor
Sit as far back in the chair as possible
Adjust monitor till:
- Your natural gaze falls about the top one-third of the length of the screen (avoid chin tuck and poke).
- Bifocal users should lower the monitor so that text can be viewed through the proper prescription.
- Tilting the screen upward slightly can also help prevent neck tilt.
Sit as far back in the chair as possible.
The distance between you and the monitor should roughly be arms length apart
Personal visual acuity and sensitivity can also determine the correct distance.
Documents
Reference documents, especially when used frequently, should not be placed flat on the work surface. Instead, use a document holder. Traditional holders position the document adjacent to the monitor, however We recommend models that allow the user to place several items directly in front of the body, between your keyboard and monitor, avoiding awkward neck postures and maximizing productivity.
Telephone
A headset should be used for frequent phone users.
It allows for hands-free operation, which will eliminate cradling of the phone between shoulder and ear while writing, handling documents or using the computer.
Sit to stand workstation
In any workstation, change of posture is a key component of good ergonomics. Sit-to-stand workstations facilitate the ability to change posture beyond a seated position to one of standing as well. Static posture, though, whether sitting or standing can lead to muscle fatigue.
A sit-to-stand workstation can be created by a number of means, including desk add-on’s (trays and arms), manual lift tables or electric drive adjustable legs that can be retrofitted as an option to a pre-existing table top.
Departmental approach to sit/stand workstations vary. Where the introduction of a sit/stand workstation is possible, the Safety Office supports the installation. Because each workstation is unique, Plant Operations Design can assist in determining the best sit/stand style to be used.
If a sit/stand workstation is being recommended because of a medical need, the Medical Accommodation process administered by Occupational Health needs to be followed. Once an accommodation request is approved, Plant Operations Design can assist in determining the best option for the style of sit/stand to be installed.
Setup:
The same concept of proper ergonomic setup mentioned above applies to a sit-to-stand workstation. Setup your sitting workstation first by applying the information provided above. In the standing position, the distance between monitor and keyboard height will remain the same. The only change needed is the ideal height of the overall table. To find the ideal height of the table for standing, adjust the height so that your shoulders are relaxed and elbows angle is 90 degrees.
Laptop setup
Administrative control:
"Ergo breaks"
One of the best ways to prevent injury, discomfort and fatigue is to take an ergo break - a pause or change in activity that allows muscles, joints and tissues that have been working to recover and rest. Muscles that remain in a static posture will fatigue, circulation will decrease, and you will notice discomfort. This may mean taking a short pause in activity to focus on a different task, rest your eyes, and most of all, change position. Prolonged sitting is one of the major risk factors for low back pain, so give your back a break and stand, walk, stretch and exercise. It may also mean switching to another task that requires the use of different muscle groups and postures.