Workplace Ergonomics Report PDF

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Summary

TABLE OF CONTENTS 1 INTRODUCTION............................................................................................................. 1 Computer ergonomic workstation.................................................................................. 2 OVERVIEW OF ITEMS NEEDED....................

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TABLE OF CONTENTS

1.0 INTRODUCTION.............................................................................................................2 1.1 Computer ergonomic workstation..................................................................................2 2.0 OVERVIEW OF ITEMS NEEDED................................................................................3 2.1 Chair...............................................................................................................................3 2.1.1 Adjustable height.....................................................................................................3 2.1.2 Backrest...................................................................................................................3 2.1.3 Armrests..................................................................................................................4 2.1.4 Seat pan...................................................................................................................4 2.2 Keyboard........................................................................................................................5 2.3 Mouse or stylus..............................................................................................................5 2.4 Monitor...........................................................................................................................6 2.5 Lighting..........................................................................................................................7 2.6 Overall workstation........................................................................................................8 2.6.1 Desk.........................................................................................................................8 2.6.2 Document holders...................................................................................................9 2.7 Summary......................................................................................................................10 3.0 DESIGN OF ERGONOMIC WORKSTATION..........................................................12 4.0 CONCLUSION................................................................................................................13 5.0 LIST OF REFERENCES...............................................................................................13

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1.0

INTRODUCTION

1.1

Computer ergonomic workstation

Generally, ergonomics is defined as a science of arranging things so that people can access them easily and safely (Merriam-Webster, 2014). More specifically, ergonomics is the science of designing the job to fit the worker rather than physically forcing the worker’s body to fit the job (Stubbs, 2000). Practice of ergonomics improves working efficiency, comfort and easiness to use without compromising health and safety. According to Palm (1997), a workplace, which is ergonomically deficient, may not cause immediate pain, because the human body can adapt to a poorly designed workplace to some extent. However, in long term, the workplace deficiencies will surpass the body’s coping mechanisms, resulting in pain, mental stress, decreased performance and poor quality of work (Murphy, 1997). A computer ergonomic workstation is an ergonomically designed area of an office which accommodates a desktop computer and all of its peripherals. Ergonomic design means that the user should not have to assume uncomfortable positions in order to perform his or her duties (Pollick, 2010). Workstation ergonomics is used to determine how the workplace can be designed or adapted to the worker in order to prevent a variety of health problems and to increase efficiency (Asaolu & Itsekor, 2014). Working for prolonged period in an ergonomically deficient work place can lead to Musculoskeletal Disorders (MSDs). Globally over the past decade, there is 25 percent increase in the individuals suffering from musculoskeletal conditions (Connelly, Woolf & Brooks, 2006). Ergonomics emerges as a concern because majority of these musculoskeletal conditions are related to computer use (Karsh, Moro & Smith, 2001). Improper workstation design and faulty posture are risk factors related to computer use. These typically happen when uncomfortable postures and body movements are often maintained over a long period of time (Chiu et. al., 2002). A little knowledge of the principles of ergonomics of work station setup and exercises can prevent a lot of discomfort and maximize productivity.

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2.0 OVERVIEW OF ITEMS NEEDED 2.1

Chair

The chair used in the office should provide adequate support for the user while working and should not place unnecessary stress on any part on the user’s body and should positively encourage optimum posture while allowing for comfort and efficiency and minimum muscle fatigue. Chair is the tool that is used to support the spine when working. Extended period of static sitting postures causes decreased circulation, stiffness and pain in the joints. Prolonged duration of continuous work increases the risk of cumulative trauma disorders, which may result in long-term disability (Karsh et. al., 2001).

2.1.1

Adjustable height

Suitable design of the work chair is essential for preventing musculoskeletal disorders of the back, legs, buttocks and arms. The height of the chair should be one that enables the feet to rest flat on the floor with the thigh roughly parallel to the floor. This therefore requires the use of a height-adjustable chair in order to help in placing the user at a proper height for typing and viewing the monitor, especially when height-adjustable tables are not available. The chair used also must be of appropriate size to accommodate the user. The recommended adjustable seat height is between 38 and 56 cm and depth is adjustable between 33 and 48 cm (Woo et. al., 2016). The use of height-adjustable chair would greatly reduce the pressure on the back of the user’s leg. Chair that is too high will lead to a concentration of pressure on the back of the knees, meanwhile one that is too low will lead to concentration of pressure on a small area of the buttocks (Lueder, 1986).

2.1.2

Backrest

Backrests functioned in a way that provides sufficient lumbar support to the user. It is favourable for the height and inclination angle of the backrest to be adjustable so that it will be able to support the back of users in a range of sitting postures. Grandjean (1984) recommended a backrest with height of 50 cm and a width of 48 cm, which is compatible with the upper back width obtained from the analysis of large-male anthropometry. However, Woo et al. (2016) recommended the height of the backrest to be between 45 and 53 cm, with 3

width between 36 and 48 cm. The backrest tilt angle also plays an important role in ergonometric. The backrest of the chair should have a tilt angle of between 90° to 120° in order to provide the optimal angle for reading and computing to the user.

2.1.3

Armrests

Armrests are used to support the arms when using keyboard and mouse and are essential to ensure optimal seating posture. The accurate use of armrests will help to reduce muscle loads on the arms, shoulder, and neck as well as reducing pressure on the spine and supporting task-related movements (Lueder & Allie, 2004). For this purpose, a chair with height adjustable armrests is favourable to ensure that the location of the armrests is not too high or too low from the user. In the event where the armrests is too high or too low, this will cause the user to lean on one side when they are using the armrests thus leading to discomfort and strained on arm muscles and shoulder. Therefore, armrests with appropriate height adjustment and sufficient padding are necessary to reduce the pressure on the undersides of the forearms and elbows (Woo et. al., 2016).

2.1.4

Seat pan

The seat pan for the chair should be large enough to provide supports for thighs and buttocks but not so long that the front edge presses into the backs of the user’s lower legs. The seat pan also should have a waterfall front edge (downward-curving or rounded) so as to reduce the pressure on the underside of the thighs.

Figure 2.1: Ergonomic chair setting at computer workstation 4

2.2

Keyboard

When working at a keyboard, the operator should be sitting with the upper arms hanging naturally from the shoulders. The elbows should be bent at roughly a 90-degree angle when the fingers are in typing position on the home row of the keyboard. This posture allows the arms and wrists to be held in a natural and relaxed position that puts the least amount of physical stress on muscles and joints. Use of ergonomic keyboard is favourable so as to minimize muscle strain and a host of related problems such as carpal tunnel syndrome or other forms of repetitive strain injury (Magnan, 2007). Ergonomic keyboard is designed in a V-shape, to allow the right and left hands to type at a slight angle more natural to the human form.

Figure 2.2: Examples of ergonomic keyboards

2.3

Mouse or stylus

Input devices such as computer mouses, trackballs and digitizing tablets are used to perform a variety of types of computer work ranging from word processing to computer aided design (CAD). In terms of the position of mouse or other stylus, it should be placed at the same height as the keyboard and in the same plane, to either side of it. The mouse should be placed as close to the worker’s side as possible at a height that allows the upper arm to hang relaxed from the shoulder with a "neutral" wrist position, with the hand in line with forearm. This position causes the least physical stress. The mouse should be also placed so the cord and items on the desk do not limit movement. The mouse or other hand-held input device should not contribute to cramped hand postures. This may require consideration of different-sized devices for different hand sizes. 5

The device should be shaped so as to minimize bent wrist postures, or, failing that, the forearm should be supported on a raised smooth surface to allow a comfortable wrist posture.

Figure 2.3.1: Mouse’s shape that minimize bent wrist postures

2.4

Figure 2.3.2: Wrist pad to support wrist posture

Monitor

Apart from the spine, the eyes experience a lot of stress when working on computers for extended periods of time, and according to the Canadian Centre for Occupational Health and Safety (2009) bad positioning of the monitor can lead to work related musculoskeletal injury. Monitors should be placed so that the top of the screen is at the operator’s eye level. Generally, between 20 and 40 inches (arm’s length) from the eye to the front surface of the computer screen is considered as an ideal viewing distance. The size of the monitor often dictates viewing distance. If the monitor is large the workstation should be large enough to accommodate it. The use of flat screen monitors allow for better space use and more flexibility in screen position. In addition, the monitor should be slightly tilted at the angle of between 15° to 30° below gaze inclination (Hagberg & Rempel, 1997). If the screen is too low or too high, the muscles of the neck must work continuously to hold the head in a viewing position, which may result in fatigue and discomfort. If the screen is viewed continuously or frequently it should be directly in front of the worker to avoid having to keep the head turned to one side. Improper viewing distances or positions may result in fatiguing head positions and in visual fatigue caused by the effort needed to focus. Appropriate monitor placement reduces the overhead glare and minimizes the exposure to forceful exertions and awkward postures. This reduces possible health risks such as excessive fatigue, eye strain, and neck and back pain. Suitable positioning of the computer monitor is essential to prevent neck and eye strain. 6

Figure 2.4: Ergonomic monitor’s setting for computer workstation

2.5

Lighting

When computer work environments are being planned, both overall lighting levels and the positioning of lights and windows must be considered. Generally there are different types of lighting available in the workstations such as ambient light which refers to the overall room lighting, task light which is the light use for specific task area (typically bright, flexible and directional), and natural light that comes from a window or door. Area lighting (overhead fixture) levels from 300 to 500 lux are generally considered to be the most appropriate for computer work. Excessive light levels may "mask" (or partly hide) characters or whatever is shown on the screen and create more and brighter sources of glare. Glare is caused by large differences in light levels within the visual field. The eyes try to adapt to these large differences and visual fatigue and discomfort may result. In addition, the computer operator may adopt a poor posture while trying to reduce the glare by changing his or her orientation to the screen. This may result in neck and back pain. In general, there are three types of glare which are direct, indirect and masking. Direct glare occurs when there are bright light sources directly in the operator’s field of view. Windows are often a source of direct glare. Indirect glare occurs when light from windows or overhead lighting is reflected off shiny surfaces in the field of view, such as terminal screens, desks and other office equipment. Light from sources directly overhead causes masking glare on the screen, partly obscuring what the operator is trying to focus on.

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In order to reduce these glares, the use of light-absorbing binds or curtains is therefore essential. In addition, the methods used to control light from windows should allow for user control such as the use of roller, vertical or venetian blinds, or thick curtains. Care should be taken in the selection and sizing of the coverings to ensure that the light can be fully blocked.

Figure 2.5: Different types of glares and their sources 2.6 2.6.1

Overall workstation Desk

The best way to provide the proper screen and keyboard heights for all operators is to use split-level tables or desks that allow each height to be adjusted independently. This allows for proper work postures for a range of user sizes. However, a fixed desk of suitable height, the correct use of an adjustable chair, and a footrest and/ or monitor stand where necessary, will also allow for suitable postures. The recommended height for any fixed desk is approximately 73-76 cm. Any table, desk or stand used for computer work must be deep enough for both the keyboard and the monitor to be placed in front of the user at the recommended distance and to place objects that the user most often use within their reach. If work surfaces are too high, users must raise their arms and shoulders. This requires continuous muscular effort, called "static effort" or "static loading". This static effort in the arms and shoulders may be fatiguing, and it may also hinder blood flow, adding to discomfort and even to the risk of injury. In addition, the wrist may be flexed (bent forward) to reach the keys, placing stress on forearm muscles and wrist tissues. If the work surfaces are too low, 8

the worker must lean forward, placing stresses on the arms and back. As well, the wrists will tend to be bent back, also stressing the muscles and tissues. This is supported by the findings of Sauter et. al. (1990) in their study on workstation design and musculoskeletal discomfort which found that arm discomfort was associated with keyboard height above the elbow level.

2.6.2

Document holders

Computer work often involves entering information from source documents. These should be located beside the screen and in the same plane. This reduces the size and amount of head and eye movements between the document and the screen and decreases the likelihood of muscular and visual fatigue. The best way to position documents correctly is to use an adjustable document holder. These are usually mounted on a flexible arm that is fixed to a base or clamps to the edge of the desk. The clamping type is preferable in the event where the space on the desk is limited.

Figure 2.6: Example of ergonomic document holder

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2.7

Summary

This part of the report will summarise all the items needed for the creation of a computer ergonomic workstation by arranging all the items listed above based on their priority as well as the justification for why such item is needed.

No . 1.

Items Chair

2.

Monitor

3.

Keyboard

4.

Mouse

5.

Lighting

Justification Chair is the most important item that is used to support the spine when sitting for a long period of time. Chair that is not ergonomic may lead to sitting position that adds stress to the structure of the spine. It is therefore of utmost important to have an ergonomic chair that provide adequate support to the lower back region of the body. The characteristics of chair that is ergonomic have been described and discussed above. As mentioned above, apart from the spine, eyes are another part of the body that suffer from high amount of stress as a result of continuous usage of computer. The position of the monitor, the viewing distance, and the degree of inclination of the monitor are therefore among the most important conditions to consider, second to the chair, in preparing for an ergonomic workstation so as to prevent eye-related problems such as eye fatigue, headaches, and other forms of musculoskeletal injury. The third most important item for preparing an ergonomic workstation is the use of keyboard. Carpal tunnel syndrome is among one of the most common musculoskeletal injury associated with the prolong use of computer during working hours and this syndrome typically occur due to the use of keyboard or mouse. The use of ergonomic keyboard and the correct placing of keyboard helps in combatting against the occurrence of such syndrome. Apart from keyboard, the incorrect use of mouse also may lead to carpal tunnel syndrome. The use of ergonomic mouse helps to correct the posture of the wrist when using it therefore reducing the risk of occurrence of such syndrome. In addition, the use of mousepad that comes with a wrist support ensure that the strain on the wrist can be substantially reduced when the mouse is use and proper support can be given to the wrist to avoid injury. In office settings, proper lighting makes all work tasks easier. This is because people receive about 85 percent of their information through their sense of sight. Appropriate lighting, without glare or shadows, can reduce eye fatigue and headaches; it can prevent workplace accidents by increasing the visibility of moving machinery and other safety hazards. Good quality lighting also reduces the chance of accidents and 10

6.

Workstation - Desk - Document holder

injuries from "momentary blindness" (momentary low field vision due to eyes adjusting from brighter to darker, or viceversa, surroundings). The last items to be considered when preparing for an ergonomic workstation are the desk as well as the use of document holder. It is necessary to consider the size of desk that is most suitable and appropriate to accommodate the desktop and all other items mentioned above. Document holder on the other hand helps to reduce the strain on the eyes when an employee is required to copy information from a source document as it reduces the size and amount of head and eye movements between the document and the screen and decreases the ...