take frequent breaks · 2008. 11. 18. · take frequent breaks workstation design factors an ideal...

Take Frequent Breaks

Foreward

Healthy Choices for Computer Users was createdin a joint effort by members of the CumulativeTrauma Prevention Group, an ad hoc committeewith representatives from UCSD's Office of Envi-ronment, Health & Safety, Employee Rehabilita-tion, Business Office, Employee Benefits, HandRehabilitation and Work Evaluation Centers, aswell as Applied Risk Management.

Questions regarding this publication? Please con-tact EH&S Industrial Hygiene Division:

E-mail: [email protected]: (858) 534-1075Web site: http://blink.ucsd.edu/go/ergo

Table of Contents

Introduction ...........................................1Workstation Design Factors .....................3Reducing Stress In Your

Eyes ...............................................4Neck...............................................8Hands, Wrists & Arms ......................9Back & Legs .................................. 13

Radiation Emissions.............................. 15Summary ............................................ 17Checklist ............................................. 17Resources ...........................................18

http://blink.ucsd.edu/go/ergo


Introduction

Personal computers have become indispensablein all aspects of university operations. Comput-ers provide an incredible opportunity for person-nel to achieve much greater levels of productiv-ity. They afford speed, versatility and extendunlimited capabilities for their users. In fact,computers have radically changed the very na-ture of how we perform many of our daily tasks.University personnel now spend a much greaterproportion of their professional time activelyusing their PCs. Unfortunately, many of theseindividuals are discovering there can be painfuland serious health problems resulting from over-use of their computer. In fact, repetitive motioninjuries and cumulative stress arising from com-puter usage constitute the fasting growing cat-egory of employee injuries reported in majororganizations throughout the country. UCSD isno exception.

Healthy Choices for Computer Users was specifi-cally developed to share important informationconcerning operator injury patterns. Throughredesign of your computer workstation and spe-cific job tasks, coupled with greater personalawareness, use of assistive devices, and exercis-ing, many of the problem areas can be success-fully eliminated. Studies have shown that apoorly designed computer setup can have anegative impact on the user's comfort and pro-ductivity. Recognizing this fact, it becomes im-portant to take a proactive approach to identify-ing and resolving these problems. Off-work ac-tivities involving these same repetitive motionsmay also be contributing to chronic discomfort.

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Solutions to these problems may need to includemodifications in these pursuits, as well.

This booklet is designed as a self-help guide toprovide the reader with basic ergonomic prin-ciples that, when applied, will significantly re-duce on-going stress-related problems associ-ated with computer activities. You are stronglyencouraged to apply the recommendations pre-sented in each section to your particular work-station. Make whatever adjustments seem rea-sonable and necessary. You will reap immediatebenefits with greater personal comfort and pro-ductivity.

Most workstations at UCSD are inadequatelydesigned with respect to basic user comfort. Partof the problem stems from the use of inappropri-ate types of desks, chairs, tables, lights, etc.,which simply do not provide proper support andproportions. It is not the goal of this publicationto encourage computer operators to rush outand purchase new furniture and accessories.Rather, it will focus on low-cost modificationsand simple adjustments which will alleviate agreat deal of the potential problems.

Hundreds of research studies from around theworld have examined every conceivable aspectof computer workstation design. Among the bestof these investigations was a ten year studyconducted by NIOSH (National Institute of Occu-pational Safety and Health) which studied thou-sands of computer users from various industriesthroughout the United States. The findings ofthis research serve as the foundation for theinformation presented in this booklet.

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Workstation Design Factors

An ideal computer workstation, ergonomicallyspeaking, is one that provides the greatest com-fort and safety for its operator.

The key to achieving this comfort is makingcertain your body is always supported in a re-laxed, natural position when using your com-puter. This means ensuring your activities do notforce you into awkward, stressful positions. Theworkstation should be arranged according toyour pattern of movement, so working materialsare easily accessible.

The following section focuses on reducing stressand fatigue in specific body areas. Eyes, neck,arms, wrists, hands, back and legs are vulner-able areas when using your computer in a poorlydesigned workstation environment.

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Reducing theStress in Your...

Undoubtedly, the single greatest complaint ex-pressed by computer users is chronic eye fa-tigue. The nature of the close work on the VDTtends to cause general eye strain, dry eyes,tearing, blurred vision and temporary sorenessfor many of us. Although it may not be possibleto completely eliminate all eye discomfort, simplechanges in the workstation setup will significantlyreduce the symptoms.

A major contributing factorto having dry, itchy eyesresults from a reduction inthe frequency of your eye'sblink rate while viewing themonitor. The human eyecleanses and refreshes it-

self automatically many times per minute. How-ever, staring and concentrating at the brightmonitor causes your eye's blink rate to slowdown significantly. The corneal surface drys outresulting in irritated, red, tired eyes.

Another factor contributing to eye fatigue resultsfrom simple muscle exhaustion. Small muscles inthe eye are responsible for changing the shape ofits lens to permit close viewing. Unless there is aneffort to consciously relax your eyes, thesemuscles build up lactic acid, fatigue, and becomesore. Take frequent breaks away from yourcomputer to allow your eyes to fully relax andrefresh themselves.

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(Eyes)


Use the 20/20/20 rule: After 20 minutes ofcomputer work, look at a distance 20 feet awayfor 20 seconds. Periodically gazing across theroom or out a window will allow your eye musclesto relax and receive freshly oxygenated blood,thus removing lacticacid. The eyes will usu-ally recover very quicklywhen allowed to rest.

Research verifies thatmany of the visual prob-lems experienced bycomputer users alsoarise because their vi-sion may need correction. Eye fatigue may beyour body's signal to have your vision checked byyour health care provider.

Persons wearing bifocals may experience troublein comfortably reading text flowing across thescreen because of the graduated layers on thelens themselves. Special glasses designed to beworn when using your computer are now avail-able. Their prescriptive formula isspecific for the routine distancesassociated with computer entry.

Computer monitors should haveboth a contrast and brightnesscontrol switch. Maximum contrastand minimum brightness usuallyproduce the least strain on theeyes. Adjust your monitor for maximum per-sonal comfort. If characters on the screen ap-pear to be fuzzy or out of focus, it may not befaltering vision at all. Some monitors lose theircharacter crispness or clarity due to technical

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Resting your eyesallows freshlyoxygenated

blood to removelactic acid....


problems. Professional repairs should be soughtto correct the problem.

Copy stands should be placed at the same heightas your monitor. This allows the eyes to moreeasily scan back and forth at the same focaldistance, rather than looking down on the deskand then readjusting back to the monitor. Thissimply reduces unnecessary repetitive motionwhich causes fatigue.

Extraneous light striking the screen and causingexcessive glare may come from many sources inyour area. Situating your monitor directly in frontof a large window may create strong backlightingconditions which can result in squinting, eyestrain, and the dreaded "crow's feet" wrinkles.Conversely, computers with large windows di-rectly behind the operator will also tend to haveexcessive natural glare splashing across thescreen. To resolve both problems, place yourscreen parallel to windows to minimize glare.

Copy StandLevel WithMonitor

PlaceMonitor

Parallel ToWindows

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Most monitors come equipped with a pivotalbase to allow for tilting up and down and swivelingfrom side to side. Find the best angle whichreduces glare. Many newer monitors are nowbeing designed with a matte finish surface on thescreen to minimize reflection of light off walls,bright clothing, etc.

Fluorescent lights tend to be very white andharsh on the eyes. If your workstation has abright light above it, place a cardboard hood overthe monitor to provide shade across the screensurface. Be sure not to block the ventilationopenings. Special light diffusers are also com-mercially available which direct overhead light-ing straight downward, rather than sending itacross open areas in all directions. This tonesdown the overall room lighting significantly, butretains full spotlighting on all work areas.

Glare shields made of various materials canprovide relief from glare problems. The tintedsurface tends to diffuse light striking the screen,rather than reflecting it back. These products areavailable through the Bookstore, Storehouseand numerous other commercial outlets in SanDiego.

SPECIAL NOTE: Some glare shields are mar-keted under the promise of affording safe levelsof protection from radiation emissions. Makeyour product selection based upon how well theglare shield diffuses light, rather than worryingabout possible radiation shielding. Refer to theradiation section in this publication for a morecomplete discussion of this topic.

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Vary your activitiesthroughout the dayso that computerwork is intermittent.Changing activitiesallows your eyes torest, thus helping toreduce chronic strain. Altering activities also al-lows other muscle groups to relax and stretch.NIOSH recommends a fifteen minute break everytwo hours of intense computer activity


The average adult's headweighs about twelve pounds. It's about the samesize and weight as a bowling ball. When keptbalanced directly over your shoulders through-out the work session, strong muscles in the neckeasily adjust and support this weight. However,when the head tilts forward or backward too far,muscles become over stretched and/or con-tracted causing soreness, cramping and fatigue.

Correct monitor height is essential in reducingneck strain. The top of the screen should be levelwith your eyes. This allows your head to remainin an upright, balanced position. A monitor placedtoo low (a common problem) forces the head tofall forward as you view the screen. This positionputs unnecessary strain on the neck muscles.

(Neck)

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Take a 15 minutebreak every2 hours...


Raise your monitor by placing thec.p.u. (central processing unit)under it; using old phone books;or attaching it to a robotic, canti-levered platform which mountsto the side of the desk.

Exception - If you wear bifocals,a lower monitor will help accom-modate your need to peer throughthe lower portion of your lens with-out having to tilt your head backward.

Sitting directly in front of your monitor/keyboardallows greatest relaxation and helps avoid anytwisting motion in the neck muscles.


Research estimates thata person using a com-puter eight hours a day may make as many as80,000 separate finger and hand movementsduring a single work shift! The human body simplydoes not perform very well when expected toperform like a machine. Muscles, ligaments andtendons become exhausted and irritated and aremuch more prone to possible injuries. Not sur-prisingly, the hands and wrists are primary loca-tions for many of the chronic problems reportedby university personnel.

Carpal Tunnel Syndrome is one of the family ofafflictions collectively known as repetitive-stressdisorders. It is a serious problem affecting one orboth wrists of many computer users, particularly

(Hands, Wrists & Arms)

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those who work full-time on their VDT's. Ifunchecked, Carpal Tunnel Syndrome can lead topermanent damage resulting in dysfunction andpain in your hand(s).

The carpal tunnel itself is a small opening in thewrist area. The large median nerve, radiatingdown from the arm, passes through this tunnelon route to the fingers and thumb. When thewrist is relaxed and unstressed, ample spaceexists for the nerve to easily slide through thisnarrow passage. However, repetitive movementfrom keying, coupled with flexed wrist positionscommonly associated with working at a poorlydesigned workstation, can result in exhaustionand swelling of muscles, ligaments and tendons.The carpal tunnel's reaction to this stress is tocompress inwardly putting pressure directly onthe nerve. This pressure can result in impairmentor loss of nervous function in the first threefingers and thumb. Early symptoms of CarpalTunnel Syndrome include numbness, tingling orburning sensation in the fingers, hands or fore-arms and may progress to a loss of feeling, gripand, finally, some hand function.

The following ergonomic guidelines will help youto identify potential problem areas in the work-station environment which contribute to repeti-tive stress injuries of the hand and wrist.

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Maintain a straight line through wrist. Use awrist rest or small rolled towel. Wrist restsare small foam bars which sit in front of thekey board and provide a resting surface forthe hands.

Avoid any unneces-sary flexing in thewrist during keyingactivities. Fingers should extend straightout from the hand. Strike keys lightly whentyping.

Move the mouse using the entire hand/wristfixed in a straight line. The mouse should belocated at the same distance and height as

your keyboard.

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Use a wrist rest for support.

Detachable keyboard allows for varyingheight with respect to the monitor. Key-board should rest on a flat, hard surface.

900 -1100 anglethrough the elbow isbest. Hold arms in closeto body or resting onchair arms. Keep uppershoulders relaxed.

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Of the three positions mostof us assume during theday (standing, sitting andlying down), sitting is defi-nitely the most stressful.The human body is simplynot designed to hold itself comfortably in asedentary, seated position for extended periods.

Computers have radically redesigned the waymost of us accomplish our daily tasks. We nolonger are "required" to move around our workenvironment nearly as much as was the casewith earlier generations. Contemporary com-puter users are now able to perform all input,retrieval and data storage functions without everleaving their chairs. This incredible versatility hasa price. We literally are being "forced" to remainin this most stressful of all positions far too long.A simple solution to this problem - take frequentbreaks away from your workstation. Walk around,stretch, and exercise. This increases your me-tabolism, starts the blood circulating more quicklyand refreshes you mentally. This break in routineis exactly what your body needs to flush awaythe cumulative stress that plagues so manycomputer operators.

The following ergonomic guidelines identify po-tential stressors affecting your back and legs.Individual body size must be considered and willinfluence the height of your work surface, key-board, monitor and the design of your chair.

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Avoid anytwisted posi-

tions whichstrain musclesand ligamentsin lower back

and neck area.

Sit directly in front of your monitor.

A well-designed chair supports yourspine's natural curvature.

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Do VDT's ProduceHARMFUL LEVELS OF Radiation?

This question has been asked and researchedrepeatedly since the early 1960's when personalcomputers first appeared in the workplace. Manylong-term studies have been conducted by NIOSH,as well as many other groups around the world.The investigations have focused on whetherVDT's do emit harmful levels of radiation and, ifso, what are the possible effects to the user orthe pregnant worker's unborn child?

It has been clearly established that computers,as well as televisions and other consumer appli-ances, do produce minute amounts of radiationas by-products of their technology. This amountis extremely small and falls far below permissiblelevels established by international radiation safetyadvisory groups and the federal government.The following discussion describes how the ra-diation is produced.

Your VDT produces images essentially in thesame manner as a television. At the narrow endof the picture tube is an electron gun which firesa constant high-energy beam of electrons ontothe back of the screen. As the electrons strike theglass surface and create images, they also pro-duce ionizing radiation in the form of weak x-rays. These "soft x-rays" are essentially con-tained inside the thick glass tube. The energy ofthese x-rays is so slight that they travel only afew inches before they dissipate.

Sitting 16-24 inches from the monitor, the op-erator is so far removed from the screen that

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x-rays being produced can't reach them. Theconclusion reached by various studies confirmthat VDT users are not at risk from harmful levels

of ionizing radiation. The same research verifiesthat pregnant operators have no greater inci-dence of miscarriages or other birth relatedproblems than women not involved with com-puter operations.

Extremely Low Frequency electrical and mag-netic fields (ELF-EMF), which are other forms ofradiation termed non-ionizing, are also producedby computers. NIOSH research results indicateVDT users are working safely within acceptableestablished boundaries in these areas, as well.For more in-depth answers concerning radiationquestions, contact the EH&S Radiation SafetyDivision at (858) 534-6138.

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Summary

Computers are here to stay. Every aspect ofbusiness and research activity will continue torely heavily on their technology. It becomes theresponsibility of each computer operator to rec-ognize the risks associated with using the appli-ance, and to take proactive, corrective measuresnow to reduce potential injuries. The universitysimply cannot afford to lose your productivity orcontinue to incur rapidly escalating costs associ-ated with computer injuries.

You are encouraged to closely follow the guide-lines outlined in this publication. Compare yourwork area with the information detailed in eachsection. Make as many positive changes as pos-sible. The following is a "quick reference" checklist which identifies the major points discussed inearlier chapters.

Check List

! Sit directly in front of monitor and key-board.

! Make sure the top of the screen is at eyelevel.

! Check for glare. Close blinds, reposition moni-tor, place a shade over the screen, install aglare shield or parabolic light diffusers onceiling.

! Maintain approximately 90 degree angle inelbows.

! Keep wrists straight and aligned with forearm.

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! Sit "snugly" in chair to keep lower back wellsupported.

! Keep arms close to body when typing or usingmouse.

! Move entire hand/wrist area when operatinga mouse.

! Bring frequently used items close to workarea to avoid overreaching and repetitivestretching.

! Place feet firmly on the floor or footrest.

! Move yourself around the work area usingyour feet, rather than pulling with your hands.

! Allow adequate leg room under workstationfor stretching and periodic position changes.

Resources

UCSD offers several resource groups which canprovide you with additional services:

Blink's Ergonomics Page at

Visit the Blink Ergonomic Web page at http://blink.ucsd.edu/go/ergo for an abundance of in-formation and resources available to UCSD em-ployees.

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