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Poor placement of switches and Controls, and illegible, inaccessible or poorly lit instrument displays force console workers to maintain >ostures that can lead to overuse conditions, particularly in the neck and shoulder.

Poor placement of switches and Controls, and illegible. inaccessible or poorly lit instrument displays force console workers to maintain postures that can lead to overuse eondi-tions. particularly in the neck and shoulder. The classic typewriting and word processing positions force the hands into extrenies or niovcment with no support for wrists and 1'ore-ami. Conscquently. in addition to neck and shoulder problems. VDT operatorsexperience tenosynovitis and elbow problems.

Work lasks arc largely govemed by the design of tlie Workstation and equipment. Neverthelcss. when desie ni ng a task. consid-eration musi be given to avoiding (whereeof teasible) actions that iiuluce oeeruse eondi-tions. Of panicular importanee arc ihe fre-quency and total numhcr of repetitne move-ments and the force. speed. and din.vtiv'ii of movcmcnts. The work does not necessarily łiave to be hcavy tocause an oeeruse cer.dition. Tlierc is cuough strain in the static postnon of an unsupponcd hand. even withoui ihe stress aihlcd by typewriting or oilier repeiii:ve tasks.

l asks should bedesicned to lawę: r/.aime-nauce of good posturę and limb |v>iiior. and to avoid, or ai minimizc. repciiirir ~:otioti.

Joints should operatc within mid-range angles. Bcnding, deviation, fuli extension and fuli flex ion of the wrist, with constant supination or pronation, should be avoided (see figurę on nest pogc).

Dynamie (moving) work is preferable to static work. Continued pressure on soft lissues by tools or handles should bc minimized, particularly if there are repeaced impacts or vibra-tion. Avoid the need for cxccssive force when using squeezc grips. as is ihe casc with a caulking gun. Rcplace pinch grips (fingers only) with power grips (hand). Whcre muscu-lar force musi bc cxcncd. it should bc donc by the largcst appropriatc rnusclc groups. If a force has to bc cxcned repcaicdly, cither of the anns or Ices should perfonn the action.

The usc of muscular effort should bc rc-duccd if nccdcd to ovcrconic momentum. Momcntuin, howcvcr. sliould bc uscd to ussisi the worker when possible in conccrt with con-linuous ballistic or curvcd motions. Tlicsc arc preferable to motions that follow straight lines and result in sudden and sharp changcs in direction.

In assembly work. or otlicr typcs of vcry repetiiivc work. the hands should start simultn-

32 • OH&S CANAOA S TEN “CW-TO