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In 1995, the Bureau of Labor Statistics in the United States reported that 60 percent of new workplace illnesses were Repetitive Strain Injuries. They also found that in 1993, RSIs cost employers $20 billion dollars in workers compensation claims, and more than $100 billion dollars to pay for all of the indirect costs of RSIs such as lost work time and decreased productivity. Performing the same task over and over again, causing excessive and repetitive stress on certain parts of the body cause repetitive Strain Injuries. The RSIs caused by computer usage are usually injuries to the hands, wrists, arms, or back of the user. There are more than 100 varieties of RSI, including tendonitis, carpal tunnel syndrome, and cubital tunnel syndrome. The symptoms can range from minor muscle soreness or stiffness, to extreme pain, to inability to flex or move one s hand. Serious cases of RSI can even cause permanent damage to a person, or require years of rehabilitation. Injuries such as these occur when people continue their pattern of computer usage despite suffering from early symptoms such as sore wrists or hand muscles. Our question is why do people ignore the early symptoms of RSI? We have determined that people have deadlines to meet, their lively hood may depend on computer usage, or they simply don t believe that simply using a computer can have serious effects on their health. Currently the only routinely collected national source of information about occupational injuries and illnesses of United States workers is the Annual Survey of Occupational Injuries and Illnesses conducted by the Bureau of Labor Statistics of the United States Department of Labor. The survey, which the Bureau has conducted for the past 25 years, is a random sample of about 250,000 private sector establishments that provides estimates of workplace injuries and illnesses on the basis of information provided by employers from their OSHA (Occupation Safety and Health Association) Form Log 200 of recordable injuries and illnesses.

For cases involving days away from work, BLS reports that in 1994(the last year of data available at the time this report was prepared), approximately 705,800 cases (32%) were the result of overexertion or repetitive motion.

-47,861 disorders affected the shoulder as a result of computer usage.

-83,483 injuries or illnesses in other and unspecified over extension events.

-92,576 injuries or illnesses due to repetitive motion include typing or key entry. Of these injuries or illnesses, 55% affected the wrist, 7% affected the shoulder, and 6% affected the back. This paper will attempt to identify one common medical problem associated with computer usage such as carpal tunnel syndrome as well as discuss video display terminals problems and lighting issues, and to provide remedies to prevent these injuries or problems from occurring or reoccurring.

First, carpal tunnel syndrome (CTS) is a disabling and costly cumulative trauma disorder caused by damage to the median nerve as it runs through the carpal tunnel of the wrist. A single case of unilateral CTS costs between $22,000 and $32,000, not including lost work time, workers compensation, or other indirect costs (e.g., decreased productivity, retraining, diminished morale, etc.). Cumulative trauma disorders are repeated body movements that cause afflictions of the muscles, tendons, and nerves. Such afflictions are also called repetitive strain injuries, repetitive motion trauma, or occupational overuse syndrome. A CTD is not a specific diagnosis but a class of disorders with similar characteristics. Microtraumas are small tissue damage or tears that occur from routine stresses and are initially unnoticeable. When daily rest and overnight sleep fail to completely heal the microtrauma; residual tissue damage carries over to the next day. When the tissue damage exceeds the body s ability to repair itself over time, the problem can escalate. A CTD involving permanent debilitating damage may result. One of the best known CTD s is carpal tunnel syndrome. The carpal tunnel, a channel through the middle of the wrist, is comprised of the carpal bones on the bottom and the thick transverse carpal ligament on the top of the wrist. Nine tendons that control the fingers pass through the carpal tunnel, along with the median nerve. Pressure will build up in this space if the tendons become inflamed or if the wrist is held in an awkward position. Also, pressure will build up in the presence of certain medical conditions (e.g., pregnancy). This increased pressure can interrupt the blood flow to the median nerve. Over time, restricted blood flow damages the nerve. The disorder can affect either hand or both hands, and onset is usually gradual. Initial symptoms usually occur in the first three fingers and the palmar side of the thumb. Loss of sensation, motor weakness, dry skin, loss of coordination, and atrophy are later symptoms. Occupational risk factors for carpal tunnel syndrome include: highly repetitive work, bent wrist procedures, excessive force, especially in conjunction with highly repetitive work and deviated postures, mechanical trauma, working in cold temperatures, exposure to excessive vibration, and extended duration of effort. Personal risk factors for carpal tunnel syndrome include: conditions that cause abnormal fluid balance, such as pregnancy, oral contraceptive use, menopause, or myxedema, hobbies that put stress on the wrist, such as needlepoint, racquetball, and of course computer usage. Other factors include structural bony alterations of the carpal tunnel, such as old fractures or congenital defects, neuropathic medical conditions such as wrist size and shape, diabetes, alcoholism, smoking, obesity, arthritis, and gout. Carpal tunnel syndrome is diagnosed by utilizing the nerve conduction test. The conduction rate of an electrical impulse is measured between the forearm and the hand. Nerve damage is indicated if the nerve conduction is slower than normal. A simpler method is the Phalen s test, in which the wrist is flexed for 60 seconds. If a person has CTS, the increased pressure in the carpal tunnel will cause symptoms of pain and tingling in the affected fingers. The diagnosis of CTS can be complicated by another condition called thoracic outlet syndrome. In CTS, the median nerve is damaged in the wrist, whereas in thoracic outlet syndrome, the median nerve is damaged in the cervical region. Neck, shoulder and upper arm postures can compress nerves and blood vessels between the neck and shoulder. Symptoms are similar to those of CTS, with numbness of the fingers and the arm feeling as if it is going to sleep. Both conditions may occur simultaneously, further complicating precise diagnosis and appropriate treatment. Treatment of carpal tunnel syndrome will depend on the factors that caused the disease and its stage of development. Effective treatment must include identifying and eliminating the conditions that caused the problem, not just treating the symptoms. Initial treatment may include oral anti-inflammatory medication, steroid injection, and/or splints to hold the wrist in a neutral posture at night. During the day, splint usage may or may not be prescribed. Sometimes wearing a splint during an activity actually causes more problems and inflammation because the person has to fight against the splint to do the activity. The fit of the splint needs to be evaluated to ensure it provides adequate support and does not cause mechanical stress points on the hands or wrist. It is critical that the person with CTS ceases to work in positions that irritate the wrist. When conservative treatment is not effective, the person with CTS may require carpal tunnel surgery. This costly procedure involves cutting the transverse ligament on the underside of the wrist to relieve the pressure within the carpal tunnel. The surgery can result in decreased hand strength. Regardless of the treatment method, if the person does not avoid the activities that initially caused the problem, a relapse will occur.

Secondly, computers, and their accompanying video display terminals (VDTs), have invaded the workplace, invading job sites and occupations where they have not been used before. Over 30 million VDTs are in use throughout the United States, and the number is growing rapidly. Health problems associated with VDTs are growing at a rapid pace. Workers who use VDTs irregularly and discontinuously throughout the workday are generally not affected by VDT use. However, those workers who use VDTs continuously, from 6-8 hours during the workday, can experience VDT-related ailments and discomforts. The health problem reported most often with VDT use is increased fatigue or the earlier onset of fatigue. Fatigue may be muscular, mental or emotional, visual, or a combination. Pain, stiffness, and dizziness characterize muscular fatigue. Visual fatigue is characterized by eye discomfort due to frequent change of focus, eye irritation, headache abnormal afterimage or disturbed acuity. Whether VDT workers are experiencing one or a combination of these problems, the results are the same such as a loss of proficiency and productivity. Usually VDTs are placed in worksites on existing work surfaces that are neither adjustable nor comfortable for the majority of the workers. The individual is fitted to the task, rather than the task fitted to the individual. Physical discomfort in the neck, shoulders, arms, or hands may occur if: the keyboard level is either too low or too high, forearms and wrists cannot rest on an adequate support, workers have a marked head inclination, workers adopt a slanting position of the thighs under the table due to insufficient space for the legs, workers disclose a marked ulnar deviation of the hands when operating a keyboard. These are only a few problems associated with VDT related issues. The keys to alleviate these problems are workstation adjustability. This adjustability is the key to minimizing or eliminating the amount of discomfort caused by prolonged VDT use. VDT workstations need to be designed that:

-The furniture is as flexible as possible, adjustable to the following dimensions:

Keyboard height from floor to home row: 27.5 to 33.5 inches

Screen center above floor: 35.5 to 45.3 inches

Screen inclination to horizontal: 88degrees to 105 degrees

Keyboard home row to table edge: 3.9 to 10.2 inches

Alternatives to the standard QWERTY keyboard are not commonly available; certain designs can reduce the risk of Carpal Tunnel Syndrome

Screen distance to table edge 19.7 to 29.5 inches

Screen distance from worker to display and document: 2ft for typical 1/8 inch character height

A backrest height of 18.9 to 20.5 inches vertically above the seat surface

A backrest with a well-formed lumbar pad that offers good support to the lumbar spine between the third vertebra and the sacrum. The lumbar support should have a width of 12 inches height of 6-9 inches, and placement at 4-8 inches above the lowest part of the seat.

A footrest to keep feet from hanging from the edge of the chair

Adjustable, removable, and padded armrests to rest forearms and elbows

Thirdly, lighting is one of the major elements affecting efficiency, productivity and comfort in the workplace. Light intensity, expressed in lux, is the amount of light that falls on the work surface. Light intensity must be low enough for general comfort yet sufficiently high for visual tasks. In general, room lighting should be no more than three times brighter or three times darker than the illumination on the task. The lighting in most office environments is too bright for optimal VDT screen viewing. The illumination may be reduced by removing two bulbs in four-bulb fluorescent fixtures, removing the bulbs in every other fixture, or turning off overhead lights altogether. Supplemental desk lighting is better than overhead lighting for reading a printed copy. In consideration of our research it is imperative to consider the needs of all workers and their tasks when modifying illumination. The amount of light needed for maximum visual efficiency varies with the individual visual system. Factors such as pupil size, ability of the eyes to accommodate for nearness, and even the color of the eye affect how objects are seen. These factors play an even more important role with aging. Even with correction, visual acuity declines with age, as does resistance to glare and color discrimination. The pupil of the eye generally gets smaller with age, and therefore requires more illumination than that of younger individuals. Attention to room and task lighting can help improve acuity and prevent discomfort, annoyance, interference, and eye fatigue. Direct lighting is the light falling directly on a task. It is the most efficient type of illumination, but it tends to produce shadows and glare. Indirect lighting is light reflected off adjacent ceilings and walls. Indirect lighting produces fewer glares and is more comfortable to work under than direct lighting. However, since indirect lighting is reflected, more initial illumination is required to achieve the same illumination as direct lighting. Because of this factor, indirect lighting is less efficient and more costly than direct lighting. Computers are often situated in work environments where there are potential sources of glare such as overhead lights or window without curtains. Glare can interfere with vision and reduce productivity. Although identifying sources of glare may be easy, eliminating the sources is often more difficult. Sometimes the workspace can be arranged to move the computer terminal away from the glare, or partitions can be added to remove the unwanted glare. In addition to glare, an object will render different colors depending on the type of light source. Poor color rendering can distort color perception, increase eye fatigue, and decrease productivity. Fluorescent lamps and incandescent lamps provide good color rendering. The hidden costs of eye fatigue, decreased productivity and decreased quality of work often justify the investment in higher quality lighting. The recommended illumination level for VDT work is from 200-500 lux (20 to 50 foot-candles), but task lighting of 500-1500 lux may be needed when VDT work and paperwork tasks are combined. The following are solutions for lighting-related problems with office based computers: increasing character size and/or screen contrast on computer monitors for better legibility, preventing reflections and shadows by shielding the work area or rearranging the workstation, having a visual relief area to look at away from the computer or desk to relax the eye muscles, using antiglare screen filters or antireflective coatings on eyeglasses for computer users, alternating tasks for computer users to allow for a variety of visual tasks, and clean the monitor screen regularly to remove dust particles which can reduce legibility.

Finally, ergonomics applies knowledge about human capacities and limitations to the design of the workplace, so that the workplace fits the worker. Ergonomic programs provide management with the opportunity to: decrease workers compensation costs, increase productivity, improve the quality of work, reduce the risk of injury or illness, decrease worker turnover and absenteeism, and improve worker satisfaction and morale. In the past, many employees were not concerned about the ergonomic design of the workplace. Instead, they relied on a process of natural selection. Workers with lower capacity, whether it is strength, endurance, or visual abilities, would move out of the demanding jobs because they could not sustain the effort required. The difficulty of the job determined what percentage of the people would be fit for work. Natural selection;however, is an expensive and legally questionable alternative to ergonomic job design. The American with Disabilities Act of 1990 and the Rehabilitation Act of 1973 prohibit discrimination based on physical capabilities when reasonable accommodation is viable. In addition, the Occupational Safety and Health Administration (OSHA) has issued numerous citations against government and private agencies for workplace deficiencies. Poorly designed jobs that rely on natural selection will inevitably cause injuries to some workers before they can move out of the job. The resulting workers compensation costs often far exceed what it would have cost to make ergonomic interventions at the work site. As previously noted the cost associated with the increasing numbers of workers with cumulative trauma disorders is staggering. Costs include medical care, lost time, insurance and workers compensation, loss of material and property damage, increased errors, lost wages, training of a new worker, and administrative time and expense to hire replacement employees and manage the injury claim. The intangible costs of decreased job satisfaction, loss of motivation, and human pain and suffering often are not considered but have profound impact on the workplace.

In conclusion, carpal tunnel syndrome, video display terminals problems, lighting issues, and ergonomic design are major factors dealing with the impact of computer usage. If a quality, effective ergonomic program exists then people will worker smarter, not harder. Management will see measurable results in terms of protecting the work force, increasing productivity and quality, decreasing workers compensation expenditures, and reducing absenteeism and employee turnover. We have determined that adverse impact of computer usage does exists, but if we are proactive rather than reactive with our preventive measures then these problems identified can be eliminated.


1. Chaffin, D.B., and Anderson, G.B., Occupational Biomechanics, 2d ed. New York: John Wiley and Sons, Inc.,1991.

2. Dainoff, M. J., Design of Sitting Machine Crucial to Office Efficiency, Contract 27:6, June 1985.

3. Dul, J., Ergonomics for Beginners, Taylor and Francis, London, 1994.

4. Eastman Kodak Company, Ergonomics Group, Ergonomic Design for People at Work, New York: Van Nostrand Reinhold, 1986.

5. Godnig, E.C., Computers and Visual Stress, Abacus, Grand Rapids, Michigan, 1991.

6. Grandjean, E., Ergonomics in Computerized Offices, Bristol: Taylor and Francis, 1987.

7. Lueder, R.K., Why Your Employees Can t Sit Still, Office Ergonomics Review, October 1984.

8. Technical Bulletin, Medical (TB MED) 506, Occupational Vision, U.S. Army Environmental Hygiene Agency, APG, Maryland, 1981.

9. Title 41, Code of Federal Regulations (CFR), Section 101-20.107, Energy Conversation, U.S. Government Printing Office, Washington, DC, 1996.

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