OFFICE ERGONOMICS The Art & Science of Fitting the Work to the Person What is Ergonomics? By the end of this chapter, You will be able to: Demonstrate a general knowledge of office ergonomics Identify common office ergonomic risk factors and solutions to reduce these risk factors Understand basic methods of identifying, selecting, and implementing office ergonomic solutions Select appropriate engineering and administrative controls to reduce office ergonomic risk factors Adjust an office swivel chair to an appropriate setup when seated at a workstation Organize the working environment to achieve an optimal working position Perform a full office work station ergonomic analysis and present findings to classmates 1
What is Ergonomics? Ergonomics refers to the interaction between the individual, their work and work environment so that human capabilities are reinforced without exceeding human limitations. What is Ergonomics? Ergonomics is involved in the interaction of the three components of all work tasks: The Work The Worker The Workspace 2
An example of poorly set up workstations. Another example. 3
Key Risk Factors Awkward Postures Repetition + 4
What Does Ergonomics Aim To Do? The aim of Ergonomics is to minimise the mismatch that occurs between the person and the job or match the capabilities of humans and the requirements of the job they are expected to perform. Where possible, all attempts should be made to fit the job to the person. Ergonomic Assessment Additional Benefits: Improve comfort Decrease fatigue Enhance job satisfaction Increase productivity Extend work life Protect enjoyment of many life activities 5
Workplace Injuries Back pain Shoulder and arm pain Headaches Providing a telephone headset can reduce the incidence of headaches caused by cradling the phone in the neck while taking a message. Lighting Workers should be able to see clearly. Safely perform their work. Measurement of light levels is in lux. Examples of levels for reference material: good, simple detail - 240 Lux average detail - 320 Lux poor, fine detail - 600 Lux 6
Work Rest The length of the pause and how often they are taken depends on the work, the person and other factors Frequent short pauses are preferable to infrequent longer pauses. Staff should be encouraged to take regular rest breaks from a given task, even if this means changing the task. Body Mechanics T d d li t j i t t f l Tendons and ligaments cross over joints to form levers. The best, strongest and safest work position is when the joints are at mid range. 7
Muscle Activity Dynamic muscle activity when joints are at mid-range. Static muscle activity when joints are at their extreme range. Above, all joints at mid-range causing dynamic muscle loading. This is a comfortable posture. 8
Occupational Overuse Syndrome A collective term for a range of conditions characterised by discomfort or persistent pain in muscles, tendons and other soft tissues with or without visible symptoms. Contributing Factors Repetitive movement Sustained or constrained postures Forceful movements Incentive schemes that influence work rate Tight deadlines Dependent on the duration and frequency of the tasks being performed. 9
How Injuries Occur? Static Muscle Contraction Muscles Tense Blood Flow is reduced Muscle Nutrition is reduced Waste products (lactic acid) build up Muscle pain and fatigue Injury/Disability Efficient Posture Places minimal or balanced stress on different body parts. Requires minimal muscular effort to sustain. Is perceived as comfortable by the individual. 10
Efficient Posture It is important to reinforce that all persons should vary posture regularly and usually between sitting and standing/walking. For example, rather than place a printer on a desk, locate it where the staff member has to get up and walk to retrieve printed documents, (dynamic office) Setting Up The Workstation Work reach Most frequently used items should be within approximately 350-450mm. Less used items can be at a further distance. This is a fundamental of ergonomics and eliminates unnecessary work. 11
Work surface height - standing Type of work performed. Items being handled. Tools and controls used Height of the workers When setting up an area such as a bench or counter for work to be performed while standing the above factors should be taken into consideration. Work surface height - standing Benches for collating/stapling - below elbow height. Benches for writing - above elbow height. Recommended height for reception counters - 900-1100mm. However, depends on worker s height. Recommended dimensions for seated workstations can be obtained from the toolbox on the OH&S web page. 12
Work surface height - sitting Most workers can manage with a fixed height work area if chair is adjustable. Clerical Work - adjust chair height so top surface of desk is just above elbow level. Keyboard work - home row of keyboard should be at approximately elbow height. Allow adequate clearance for thighs. Seat Design Main principles are: Spine should be supported using the backrest. Static loading needs to be minimised. Features should include: A backrest that is adjustable in angle and height and depth (not always available). Cloth covered back and seat. Curved front edge. 13
Seat Design (cont.) A good chair should have: Gas strut for height adjustability Five star base for stability. Kneeling chairs or exercise balls only to be used with written medical recommendation. Seat Design (cont.) Executive chairs have limited adjustability. 14
Seat Design (cont.) Arm A rests are usually unnecessary. Higher (drafting) chairs are usually harder to get up onto, the ring may cause tripping. Castors are suitable for carpeted floors. Glides to be used on hard floor surfaces. Keyboards Should be placed in front of the screen and directly in front of the user so that there is no need to twist or rotate to use it. Should be placed near the front edge of the desk to reduce the reach distance. 15
Keyboards (cont.) Feet at rear of keyboard should be kept in a lowered position to minimise the height and angle of the keyboard. Where possible the keyboard should be moved away to allow the work surface to be used for other tasks such as writing. Keyboards (cont.) Split keyboards enable the joints to adopt a neutral posture while keying. 16
Keyboards (cont.) Another split keyboard. Wrist Rests The use of wrist rests should be viewed with some caution. The whole hand should move and not be kept in one position with the fingers reaching sideways. 17
Wrist supports (keyboard) Wrist Supports (mouse) Mouse mats with, a pad for supporting the wrist, come in various shapes and styles. 18
Computer Screens Top of the screen should be at horizontal eye level or lower, to minimise neck flexion. Where large screens are used, may need some of screen above horizontal eye level. Screen should be 350-750 mm from eyes. Distance can vary with individual preferences. Computer Screens (cont.) Workers wearing bifocals may tilt head back which may result in neck discomfort. Multifocal lenses not suitable for VDU s. Workers may purchase glasses prescribed for computer, or position computer screen as low as possible and with an increase tilt backwards, if they have no other glasses. 19
Document Holders Adjustable document holder may reduce forward neck inclination which may cause neck strain. Documents should be placed level to screen or between keyboard and the screen. Reading documents resting on the desk for prolonged periods may cause neck and shoulder strain. Footrests Footrests are required by people who are unable to place their feet flat on the floor when sitting in a correctly adjusted chair. A correctly adjusted foot stool should allow the person s legs to be at right angles with no pressure on the underside of the thighs. 20
Mouse and Trackball The mouse should not place undue pressure on the wrist and forearm muscles: Avoid stretching the arm in extension. Place the mouse beside the keyboard. Ensure mouse operates smoothly with the minimum of force. Mouse and Trackball Keep the arm by the side of the body with the forearm supported by the work surface. Move the keyboard out of the way if necessary. Avoid constant use without rest breaks. Learn to use it with either hand. 21
Mouse and Trackball Other issues: Clogging clean regularly, discard if bad. Optical mice preferred as no clogging. Cordless mice can be used when left and right handed people are using a workstation or if box located too far from monitor. Scroll wheels can reduce the amount of cut and paste. Laptop / Notebook Computers These do not allow correct ergonomics due to the compact nature of the equipment. Arm and neck position are less than ideal. When using it for a long time it is better to plug laptop into regular screen and keyboard. Can just use keyboard and mouse with screen raised to normal monitor height. Use plug in mouse rather than touch pad. 22
Lighting issues Glare: Occurs when one part of an area is much brighter than the background or vice versa. If a bright window is positioned behind a computer screen, the contrast and glare can be considerable. To Reduce Glare Control light through windows (blinds). Reduce contrast between foreground and background. Reposition workstation to reduce light falling on the work surface. Reduce general lighting to suit the task. 23
Reflection Light reflected from a surface can make it difficult to see what is on it. To reduce reflections especially from computer screens, position screen side-on to main light source. Screen Filters If repositioning doesn t work, use screen filters. 24
Shadows Shadows can encourage poor postures, therefore it should be reduced through: Reposition work. Redirecting lighting. Install adjustable task lamp. Remove barriers to light. Posture Awkward posture can arise when people find it difficult to see what they are working with and they may lean closer to the object or bring it closer to their eyes. 25
Visual Rest Eye muscles can become tired when constantly tl focused on close work. To control visual tiredness, the person should focus on an object at a different distance to work that they have been looking at. This is a similar principle to taking rest breaks by varying tasks. Assessing specific issues When specific symptoms arise, it is necessary to: Clarify the symptoms Attempt to assess the cause of the symptoms when considering the ergonomics of the work and workstation. 26
Use of a checklist The key issues are to determine: Whether equipment is positioned correctly and is being used correctly. Whether or not static muscle loading is occurring. Whether or not aspects of the work are repetitive. An ergonomics checklist and other useful documentation can be obtained from the toolbox on the OH&S web page. Hints: 1. No One Right Way to achieve a neutral posture experiment with adjusting different elements of your workstation to achieve neutral postures. 2. Adjusting one element of your workstation will affect other aspects. For example, lowering your chair height will change your elbow, wrist, hip and knee angles. 3. Healthy neutral positions can most often be achieved by adjusting existing furniture and equipment. Occasionally different items are helpful or necessary. 27
End of the Chapter http://ergo.human.cornell.edu/ 28