Introduction

Over the past few decades, computer-based technology has become indispensable in most offices. Along with the proliferation of the technology, concern about healthy, safe, and comfortable use of computers has emerged.

According to the US Census Bureau, in 2003, 70 million American households, or 62% had one or more computers. In comparison, the number of households with one or more computers was 56% in 2001.

Federal and State agencies, as well as private organizations, periodically conduct studies of potential safety and health hazards associated with radiation, chemical emissions, and ergonomics (arrangement of equipment for comfort and ease of use). To date, such studies have found various associations between computer use and illness, injury and discomfort of users. Many of those who use computers for much of their workday indeed experience symptoms including general fatigue, eyestrain or eye irritation, and physical discomfort.

The Bureau of Labor Statistics released a report in March 2003 stating that in 2001, there were 65,162 days away from work resulting from repetitive motion.

The Occupational Safety and Health Administration (OSHA) revealed that 1.8 million workers are affected by musculoskeletal disorders (MSD) each year.

Ergonomic injuries cost an average of 15 billion to 20 billion annually for workers compensation and 30 billion to 40 billion in other expenses such as medical care.

Computer work presents ergonomic risks due to:

• fixed and often awkward postures that are often maintained for too long,
• repetitive and sometimes forceful movements,
• compression on hard or sharp edges of work surfaces, and
• high pace of movements that does not allow sufficient recovery time from the effects of these movements.

Repetitive Strain Injuries develop slowly and are usually noticeable only after weeks, months or even years of work involving overuse or improper use of muscles, tendons, nerves and joints. Computer work primarily affects the eyes, hands, wrists, shoulders and arms, but can affect other areas, including the back. Some of the common symptoms of musculoskeletal injury or illness may include:

• pain, burning or aching,
• fatigue,
• loss of grip, clumsiness,
• stiffness,
• reduced control or coordination of movements, and
• hypersensitivity or tenderness to the touch.

Early stages of injury: The body aches and one feels tired at work, but symptoms disappear during the time away from work. The injury does not usually interfere with the ability to work and will completely heal if dealt with properly at this early stage.

Intermediate stages of injury: The injured area aches and feels weak soon after the start of work, until well after work has ended. The injury will still heal completely if treated promptly.

Advances stages of injury: The injured area aches and feels weak even at rest. Sleep may be affected. Even light duties and everyday tasks become difficult to perform. The extent of healing at this stage varies considerably.

Different types of Repetitive Strain Injuries or Cumulative Trauma Disorders are known by many different names, depending on the type of injury and the affected body part. The common injuries are summarized below:

Musculoskeletal Injuries (CTD's or RSI's)

Type of Injury	Symptoms
Back Strain	Pain, stiffness and/or difficulty turning, bending or moving the back due to poor posture and/or improper seating.
Eye Strain	Headaches, burning eyes and/or blurred vision due to poor screen contrast, screen flicker, glare and/or long periods of fixation on the screen.
Neck Tension Syndrome	Stiff neck, neck or shoulder tension, tight chest and/or headaches due to prolonged periods of looking up or off to the side, or holding arms extended.
Carpal Tunnel Syndrome	Pain and numbness in the index and middle fingers and weakness of the thumb muscles due to compression of the median nerve as a result of awkward wrist posture and repetitive motion.
Cubital Tunnel Syndrome	Pain, numbness and/or tingling radiating into the little and ring fingers due to compression of the ulnar nerve below the elbow as a result of resting forearms against a hard surface for prolonged periods.
Thoracic Outlet Syndrome	Pain, arm weakness and numbness in the arms and fingers due to squeezing nerves and blood vessels between the neck and shoulders, as a result of prolonged periods of looking up or to the side, or holding arms extended.
Tendonitis	Pain and swelling mainly in the hands and wrists due to inflammation of the tendon as a result of overuse.
Tenosynovitis	Pain and swelling due to inflammation of the tendon sheath and insufficient lubrication of the bone joints as a result of overuse.
Bursitis	Pain and swelling due to inflammation of the bursa or fluid filled sac located between muscles and tendons as a result of overuse.

If you notice symptoms or suspect that you may have a Cumulative Trauma Disorder or Repetitive Strain Injury, you should see a physician immediately. Prompt and proper diagnosis is critical to a complete and fast recovery. At the same time, report the condition to your supervisor or human resource manager, so that workplace interventions can be identified and implemented.

Treatment of Injury The treatment of these types of injury and illness involves several methods including:

• restriction of movement,
• application of heat and cold,
• physiotherapy and exercise, and
• medication and surgery.

The following are guidelines to help you to reduce your risk of Cumulative Trauma Disorders and allow you to work more comfortably at your computer.

Positioning the Screen

		The screen or monitor should be placed such that the top of the screen is at or slightly below eye level. A computer platform or monitor riser may be used to raise the screen if the height is too low. Wearers of bifocals, trifocals or half-width reading glasses, who use the bottom portion of their lenses to view the computer screen should lower their monitors below eye level to avoid tilting their heads back to view the screen.
		The screen should be placed directly in front of you and should not be tipped at any angle.

Positioning Reference Documents

Document holders can help minimize eye and neck movements while allowing you to view documents and books you are working with. The newer document holders (such as the one pictured below); keep your work directly in front of you, eliminating the need for repetitive lateral head movement. This dramatically reduces neck and upper back stress and significantly impacts output.

Mouse Use and Position

Hold the mouse loosely with all your fingers. Do not rest your wrists or forearm on the table while moving the mouse. Use the whole arm and shoulder to move the mouse, not just the wrist. Be careful not to lift your pinkie. Use a light touch when you click and do not bend your wrist while operating the mouse. The mouse should be positioned at the same height as the keyboard, such that your hands, wrists and forearms are parallel with the floor. Avoid placing the mouse on a surface raised above the keyboard height or ahead of the keyboard in such as way that an extended reach is required to use the mouse. All keyboard trays should come equipped with a mouse caddy.

Keyboard Trays

An adjustable keyboard tray is a tool that facilitates the placement of the computer keyboard and mouse so that the equipment can be used with hands wrists and elbows in a comfortable neutral position. Ideally, an adjustable keyboard should allow adjustments to the height and tilt of the keyboard and it should not interfere with non- computer related tasks when not in use. Finding an appropriate keyboard for a workstation will depend on many factors including the existing equipment configuration, the frequency and duration of use, the number of users, etc. Some keyboard trays are sold in two pieces, an adjustable arm and a platform.

Chair Height

Your chair should be adjusted so that there is no pressure on your legs from the edge of the seat. This will help to promote good circulation to your legs, and reduce strain on your lower back. Please ensure that your feet are flat on the floor with your thighs parallel to the floor.

Backrest position

A chair without a suitable or adjustable backrest will not provide adequate lumbar support or help to maintain the natural S-shape curvature of the spine. Adjust your backrest so that the outward curve (see arrow) of the backrest fits into the small of the back.

Laptop Computers

Laptop computers pose an ergonomic challenge - Laptops do not adhere to basic ergonomics since they have a fixed design. When the keyboard is in the proper position for the wrist, the screen is not in an adequate position for the neck and vise versa. To alleviate this potential problem we recommend the use of a laptop stand. The laptop stand should be used with an external keyboard and mouse. Using a laptop stand: Angle the laptop screen so that you can see the screen with the least amount of neck strain. Position the screen so that the top line of the screen is at or below eye level. The laptop stand should be placed between 20-40 inches away from the eye to the front surface of the computer screen.

Telephone Headsets

If your work requires you to use the telephone frequently or for extended periods of time, a headset will allow you to keep your hands free and prevent training your neck to cradle the telephone headset. Telephone headsets are available with many options, including: monaural or stereo, wired or wireless. For most people, the choice of over the head, behind the head or in the ear will be a matter of personal preference.

Glare Screens

If all measures fail, and glare is still a problem, an anti-glare screen may be helpful. Some glare screens can make the screen characters seem fuzzy. It is important to adjust the contrast and brightness when a glare screen is used. Also, be sure to clean the glare screen or monitor regularly to eliminate fingerprints and dust that can reduce the clarity of the characters on the screen.

Many of the suggestions above are relatively easy and economical to implement, and taking them into consideration before setting up a workstation will achieve maximum benefit for the least cost. Environmental Health and Safety welcomes questions about computer use. Office staff is available to assist in evaluating existing workstations or designing new ones. We also offer on-site training and up-to-date information in this area.

Please visit the EH&S web site.