COMPUTERS AND HEALTH

INDIVIDUAL AND lNSTITUTIONAL

PROTECTIVE MEASURES

CARPAL TUNNEL SYNDROME

Created by

Andrey Tarassov

Tallinn 1999

Within the past two years, substantial media attention has been directed atpotential adverse health effects of long-term computer use. Renewedconcerns about radiation, combined with reports of newly-recognized
"repetitive stress injuries" such as carpal tunnel syndrome, have led someto call for regulation in the workplace and others to rearrange theiroffices and computer labs. There is little evidence that computer use is onthe decline, however. On the contrary, more people are spending more timedoing more tasks with computers - and faculty, students and staff atcolleges and universities have some of the most computer-intensive workstyles in the world.

If, as is widely suspected, health effects are cumulative, then many of usare at risk in our offices, labs, dormitories, and homes. Unfortunately,many years will be required before epidemiological studies can providedefinitive guidelines for computer users, managers, furniture suppliers,and office designers. In the interim, individuals and institutions musteducate themselves about these issues and protective measures.

One set of issues concerns workstation design, setup, and illumination,together with users 'work habits. The City of San Francisco, which recentlyenacted worker safety legislation, cited research by the National Instituteof Occupational Safety and Health (NIOSH) into VDT operator complaints ofeyestrain, headaches, general malaise, and other visual and musculoskeletalproblems as the rationale for imposing workplace standards, to be phased inover the next four years.

A second set of issues relates to suspected radiation hazards, includingmiscarriage and cancer. A special concern with radiation is that nearbycolleagues could be affected as well, since radiation is emitted from thebacks and sides of some terminals. The most recent NIOSH study isreassuring, but some caution still seems prudent.

Ergonomics and work habits

Most people can ride any bicycle on flat ground for a short distance withno problems. On a fifty mile ride over hilly terrain, however, minoradjustments in seat height, handlebar angle, and the like can mean thedifference between top performance and severe pain. Similarly, occasionalcomputer users may notice no ill effects from poorly designed or badlyadjusted workstations, whereas those who spend several hours a day for manyyears should pay careful attention to ergonomics, the studyof man-machine interfaces.

The key to most workstation comfort guidelines is adjustability - toaccommodate different body dimensions, personal workstyle preferences, andthe need to change positions to avoid fatigue. A recommended workingposture shows the body directly facing the keyboard and terminal, backstraight, feet flat on the floor, eyes aligned at or slightly below the topof the screen, and thighs, forearms, wrists, and hands roughly parallel tothe floor. Achieving this posture may require:
. A chair with a seat pan that adjusts both vertically and fore-and-aft, an adjustable height backrest, and adjustable tilting tension
. An adjustable height work surface or separate keyboard/mouse tray (note that many keyboard trays are too narrow to accommodate a mouse pad, leaving the mouse at an awkward height or reach on the desktop)
. A height adjustment for the video display (a good use for those manuals you'll never read!)
. An adjustable document holder to minimize head movement and eyestrain
. Adjustable foot rests, arms rests, and/or wrist rests.

Studies show that many people are unaware of the range of adjustmentspossible in their chairs and workstations. Although the best chairs permitadjustment while seated, you may have to turn the chair upside down to readthe instructions. (Be careful not to strain your back while upending andrighting the chair!) If your posture deviates substantially from that inthe diagram - or if you are experiencing discomfort - experiment withadjustments or try exchanging chairs or workstationswith colleagues. A posture cushion, which maintains the natural curvatureof the spine and pelvis while supporting the lumbar region, may also provehelpful. It should be noted that any adjustment may feel uncomfortable fora week or so while your body readjusts itself.

(Some people have been advised by their physicians to use a backless
"Balans" chair, which minimizes compression of the spine and shifts thebody weight forward with the aid of a shin rest. This posture may beuncomfortable, however, since it requires stronger abdominal and legmuscles than conventional sitting positions. The Balans chair is notrecommended for overweight or exceptionally tall persons)

Light and glare

Eyestrain, headaches, and impaired vision are often a product of improperillumination resulting in glare, which is light within the field of visionthat is brighter than other objects to which the eyes are adapted. Bothdirect glare from sunlight and lighting fixtures directed at the user'seyes and indirect glare due to reflections fromvideo screens or glossy surfaces are common problems for VDT users.

Many offices are too bright for computer use, which may be a carryover fromthe days when paperwork required such brightness or the result of manyoffice workers 'preferences for sunlight and open windows. A NIOSH studyrecommends 200-500 lux for general office work; other sources suggest 500 -
700 lux for light characters on dark monitors and somewhat more for dark-on -light. If documents are not sufficiently illuminated, desk lights arerecommended in preference to ceiling lights, whichincrease reflections from video screens. Reducing overhead lighting couldalso result in substantial energy savings.

VDT workstation placement is also important. Terminal screens should bepositioned at right angles to windows, so sunlight is neither directlybehind the monitor nor behind the operator, where it will reflect off thescreen. If this is infeasible, blinds or drapes should be installed.
Screens should also be positioned between rows of overhead fixtures, whichcan be fitted with baffles or parabolic louvers to project light downwardrather than horizontally into the eyes or terminal screens.

Some users have found filters placed in front of the screen to be effectivein reducing reflections, however some dimming or blurring of the displaymay result. Experts 1advise trial and error, since the best solutionappears to depend upon specific conditions and user preferences. Finally,if you wear glasses or contact lenses, be sure your physician is aware ofthe amount of terminal work you do; special lenses are sometimes necessary.
Bifocals, in particular, are not recommended for extensive terminal work,since the unnatural neck position compresses the cervical vertebrae ..

Breaks and exercises

Working in the same position for too long causes tension buildup and isthought to increase the risk of repetitive motion injuries, such as carpaltunnel syndrome. Remedies include changing postures frequently, performingother work interspersed with computing (some studies recommend a 10-15minute break from the keyboard every hour), and doing exercises such astightening and releasing fists and rotating arms and hands to increasecirculation. Be aware, also, that the extra stress created by deadlinepressure exacerbates the effects of long hours at the computer.

Radiation hazards

For at least a decade, concerns have been raised about possible effects ofradiation from video display terminals, including cancer and miscarriages.
Earlier fears about ionizing radiation, such as X rays,have been laid to rest, since these rays are blocked by modern glassscreens. Also well below exposure standards are ultraviolet, infrared, andultrasound radiation.

More recent controversy surrounds very low frequency (VLF) and extremelylow frequency (ELF) electromagnetic radiation produced by video displays 'horizontal and vertical deflection circuits, respectively. Researchers havereported a number of ways that electromagnetic fields can affect biologicalfunctions, including changes in hormone levels, alterations in binding ofions to cell membranes, and modification ofbiochemical processes inside the cell. It is not clear, however, whetherthese biological effects translate into health effects.

Several epidemiological studies have found a correlation between VDT useand adverse pregnancy outcomes, whereas other studies found no effect. Themost recent analysis, published this year by NIOSH, found no increased riskof spontaneous abortions associated with VDT use and exposure toelectromagnetic fields in a survey of 2,430 telephone operators. Thisstudy, which measured actual electromagnetic field strength rather thanrelying on retrospective estimates, seems the most trustworthy to date. Theauthors note, however, that they surveyed only women between 18 and 33years of age and did not address physical or psychological stress factors.

A 1990 Macworld article by noted industry critic, Paul Brodeur, proposedthat users maintain the following distances to minimize VLF and ELFexposure:
. 28 inches or more from the video screen
. 48 inches or more from the sides and backs of any VDTs.
Although these guidelines seem overly cautious, a fundamental principle isthat magnetic field strength diminishes rapidly with distance. Users could,for example, select fonts with larger point sizes to permit working fartherfrom the screen. Remember that magnetic fields penetrate walls.
Over-reaction to ELF and VLF radiation can also compromise ergonomics. In acampus computer lab, for example, all displays and keyboards were angledthirty degrees from the front of desktops to reduce the radiation exposureof students behind the machines. The risks of poor working posture in thiscase appear to be greater than the radiation risks.

A final form of radiation, static electric, can cause discomfort bybombarding the user with ions that attract dust particles, leading to eyeand skin irritations. Anti-static pads, increasing humidity, and groundedglare screens are effective remedies for these symptoms.

A continuing process

Massive computerization of offices, laboratories, dormitories, and homesrepresents a fundamental change in the way many of us work and communicate.
It would be surprising if there were no adverse effects from such profoundchanges. It would also be surprising if all policy debates were based onsound scientific evidence, rather than parochial politics and mediaexposes. But, as University of Pennsylvania bioengineering professor
Kenneth Foster has written, "One difficulty is that 'safety,' if consideredto be the absence of increased risk, can never be demonstrated. A hazardcan be shown to exist; absence of hazard cannot. "

To monitor research and develop institutional guidelines, the University of
Pennsylvania has created a Task Force on Computing in the Workplace, withrepresentatives from the Offices of Environmental Health and Safety, Fireand Occupational Safety, Information Systems and Computing, Radiation
Safety, Purchasing, University Life as well as staff and faculty from the
Wharton School and Schools of Engineering, Medicine and Nursing.readers are welcome to contact the authors for information on the Task
Force and its work.

Until more conclusive research becomes available, individuals, departments,and institutions will have to weigh the evidence and make their owndecisions about protective measures to minimize the risks of computing.
And, in our opinion, the information technology managers and their vendorpartners who provided the leadership to computerize our campuses, now oweit to their colleagues to work with epidemiology and ergonomics experts tocreate computer-intensive environments that are both productive andhealthful.

Avoiding carpal tunnel syndrome: A guide for computer keyboard users

Carpal tunnel syndrome (CTS) is a painful, debilitating condition. Itinvolves the median nerve and the flexor tendons that extend from theforearm into the hand through a "tunnel" made up of the wrist bones, orcarpals, and the transverse carpal ligament. As you move your hand andfingers, the flexor tendons rub against the sides of the tunnel. Thisrubbing can cause irritation of the tendons, causing them to swell. Whenthe tendons swell they apply pressure to the median nerve. The result canbe tingling, numbness, and eventually debilitating pain.

CTS affects workers in many fields. It is common among draftsmen,meatcutters, secretaries, musicians, assembly-line workers, computer users,automotive repair workers, and many others. CTS can be treated withsteroids, anti-inflammatories, or physical therapy, or with surgery toloosen the transverse carpal ligament. Recovery of wrist and hand functionis often, but not always, complete.

Causes

Like many skeletomuscular disorders, CTS has a variety of causes. It ismost often the result of a combination of factors. Among these are:

Genetic predisposition. Certain people are more likely than others to get
CTS. The amount of natural lubrication of the flexor tendons varies fromperson to person. The less lubrication, the more likely is CTS. One studyhas related the cross-sectional shape of the wrist, and the associatedgeometry of the carpal tunnel, to CTS. Certain tunnel geometries are moresusceptible to tendon irritation.

Health and lifestyle. People with diabetes, gout, and rheumatoid arthritisare more prone than others to develop CTS, as are those experiencing thehormonal changes related to pregnancy, menopause, and the use of birthcontrol pills. Job stress has also been linked to an increased likelihoodof CTS. And CTS seems to be more frequent among alcoholics.

Repetitive motion. The most common cause of CTS that's been attributed tothe workplace is repetitive motion. When you flex your hand or fingers theflexor tendons rub against the walls of the carpal tunnel. If you allowyour hand time to recover, this rubbing is not likely to lead toirritation. The amount of recovery time you need varies from fractions of asecond to minutes, depending on many circumstances, including the geneticand health factors mentioned above, as well as the intensity of theflexing, the weight of any objects in your hand, and the extent to whichyou bend your wrist during flexing.

Trauma. A blow to the wrist or forearm can make the tendons swell and causeor encourage the onset of CTS.

Prevention

Computer keyboard users can take several steps to lower their chances ofdeveloping CTS. Some of these center around the configuration of theworkplace, or "ergonomics." Others have to do with human factors.

Ergonomics. Proper seating is crucial to good ergonomics. The height ofyour seat and the position of your backrest should be adjustable. The chairshould be on wheels so you can move it easily. Arm rests on the chair,though optional, are often helpful.

Table height. To adjust the chair properly, look first at the height of thetable or desk surface on which your keyboard rests. On the average, aheight of 27-29 inches above the floor is recommended. Taller people willprefer slightly higher tables than do shorter people. If you can adjustyour table, set your waist angle at 90 degree, then adjust your table sothat your elbow makes a 90 degree angle when your hands are on thekeyboard.

Wrist angle. If your keyboard is positioned properly your wrists should beable to rest comfortably on the table in front of it. Some keyboards are so
"thick" that they require you to bend your hands uncomfortably upward toreach the keys. If so, it will help to place a raised wrist rest on thetable in front of the keyboard. A keyboard that requires you to bend yourwrists is a common cause of CTS among computer users.

Elbow angle. With your hands resting comfortably at the keyboard and yourupper arms vertical, measure the angle between your forearm and your upperarm (the elbow angle). If it is less than 90 degree, raise the seat of yourchair. If the angle is greater than 90 degree, lower the seat. Try to holdyour elbows close to your sides to help minimize "ulnar displacement" - thesideways bending of the wrist (as when reaching for the "Z" key).

Waist angle. With your elbow angle at 90 degree, measure the angle betweenyour upper legs and your spine (the waist angle). This too should be about
90 degree. If it is less than 90 degree, your chair may be too low (andyour knees too high). Otherwise, you may need to alter the position of thebackrest or adjust your own posture (nothing provides better support thansitting up straight). (Note: If making your waist angle 90 degree changesyour elbow angle, you may need to readjust the height of your chair ortable.)

Feet. With your elbows and waist at 90 degree angles, your feet should restcomfortably flat on the floor. If they don't, adjust your chair and tableheight and repeat the steps above. If your table isn't adjustable and yourfeet don't comfortablyreach the floor, a raised footrest can help. Otherwise, you may need adifferent table.

Work routine

You need very little recovery time between keystrokes to cool and lubricatethe flexor tendons. If you type constantly, however, the need for recoverybuilds. Further, working with your hands bent upward at the wrists orfrequently bending your wrists sideways heightens the friction within thecarpal tunnel. It takes longer to recover from these motions. Working understress (deadline pressure, anger, or other anxiety) can make matters evenworse.

Many studies recommend a 10-15 minute break each hour to give yourself therecovery time you need. This needn't be a break from productive activities
- Just a break from your keyboard. Exercises can help, too. Try thefollowing:

a) Make tight fists, hold for one second, then stretch your fingers outwide and hold for five seconds. Repeat several times.

b) With arms outstretched in front of you, raise and lower your handsseveral times. Rotate your hands ten times (make circles in the air withthe fingertips).

Variety is the key. CTS occurs most frequently in workers whose motions arenot only repetitious but are kept up for hours at a time. If you use akeyboard, structure your workdays to include a mix of activities each hour.
For example, instead of typing all morning and filing all afternoon, mixtyping and filing throughout the day.

Early detection

The most painful cases of CTS are those that have gone undetected oruntreated over a long time. CTS can be caught easily in its early stages,however, and much of the pain and all of the disability avoided.

Early symptoms include a tingling in the fingers, often beginning severalhours after work activity has stopped. Because of this delay in theappearance of symptoms, many CTS sufferers don't make the connectionbetween their work activities and the pain they feel until it's too late.
The tingling can lead, over time, to stiffness and numbness in the fingersand hand, and then to severe wrist and hand pain.

For many individuals the early symptoms of CTS go unnoticed. Employers andco-workers can help one another identify the onset of CTS by watching forand pointing out any unconscious shaking of the hands, rubbing of thewrists, or unusual postures or hand positions at the keyboard.

At the first sign of CTS, you should be examined by a doctor whospecializes in hand and wrist disorders. The doctor can perform a number ofsimple tests to detect CTS, and can prescribe specific steps for avoidingthe problem.

Summary

Carpal tunnel syndrome is common among computer keyboard users. It canstrike anyone, and its consequences are serious. Awareness of the problemand its causes is crucial to preventing CTS. With proper ergonomics andattention to the work routine you can prevent CTS; with early detection andtreatment it need never become debilitating. The employer's attention tostress levels, proper ergonomics, and the early warning signs of CTS areimportant in keeping the ailment at bay in the workplace.

Summary

We hear a lot about hazards associated with working with computers, andlearn from experience that long hours at the keyboard can bring oneyestrain and various aches and pains. These concerns, and the steps we cantake to make computer work saferand more comfortable are the subject of many books and articles.

The good news is that problems can be avoided through well-designedoffices, properly set-up workstations, and sensible work habits. Checklistsand guidelines for setting up and using computers abound. The bad news:there is substantial variation in opinion as to what constitutes properworkstation set-up, quick and easy solutions to ergonomic problems are notalways possible, and checklists don't capture the complexities of thepossible combinations of people, task, equipment, and workspace.
Fortunately, there are measures that really do work. A few quick anduniversally agreed upon precautions:
. Use the minimum force necessary to press the keys.
. Vary your tasks during the day to avoid sitting in one position for several hours or performing the same hand motions without interruption.
. Take periodic breaks.
. Keep your wrists in a natural, unforced, straight position.

Bibliography of computer and health materials

. Ross, Randy. "VDTs: Are They Safe?" PC/Computing. March, 1989, pp. 146 -

7.
. Sheehan, Mark. "Avoiding carpal tunnel syndrome: A guide for computer keyboard users," University Computing Times (Indiana University,

Bloomington). July-August 1990, pp. 17-19.
. Updegrove, Kimberly H., Daniel A. Updegrove. "Computers and Health -

Issues and Protective Measures." Penn Printout. February, 1991.