Industrial ERG

CHAPTER 4 OFFICE ERGONOMICS

LEARNING OBJECTIVE

At the end of the chapter, students will have the ability to describe what ergonomics means, identify the best ergonomic posture for a workstation, demonstrate how to set up a productive computer office workstation, and identify risk factors associated with a computer workstation.

INTRODUCTION

Ergonomics, the science of designing workplaces, equipment, and jobs to fit the capabilities and limitations of workers, has shown that poor workplace design and bad work habits are counterproductive and costly.

One major problem with computer workstations is they keep an operator at that workstation, in virtually the same posture, all day long.

Our bodies are designed to be an upright, dynamic system. Chronic sitting stretches and contracts muscles inappropriately and causes stress to the body. A poorly designed workspace causes neck and back pain, decreasing productivity and job satisfaction.

The goal is to prevent musculoskeletal disorders by surveying the workplace, taking preventative steps, relying on employee input, and addressing the problems early.  Figure 4.1  depicts what a neutral posture should be for those working at a desk on a computer.

Figure 4.1  Neutral posture

This chapter will refer to the Work-Related Musculoskeletal chapter in the book when discussing the various disorders caused by poor office ergonomics.

Statistics have found that workers annually have ergonomic work-related musculoskeletal injuries, resulting in millions of dollars in total injury costs per year. Carpal tunnel comprises 0.7% and tendonitis comprises 0.2% of those injuries, while sprains, strains, and tears comprise 36.7%, and soreness and pain comprise 17.4%. The number of musculoskeletal disorders with days away from work in 2013 within private industry totaled 307,640, state government 18,410, and local government 54,560. Nursing assistants, laborers and freight, stock, and material movers, as well as heavy and tractor-trailer truck drivers, are among the highest incidence rates of injuries and illnesses due to musculoskeletal disorders (Demographics, 2014).

PRINCIPLES OF OFFICE ERGONOMICS

There are many principles to consider when assessing an office environment. Ergonomist need to consider the posture required by the workplace. This is dependent on the tasks or activities associated with the workplace. Another factor to consider is the environment of the workplace.

The goal is to arrange the environment to help the worker maintain a neutral posture, in order to minimize the incidents of work-related musculoskeletal disorders (WMSDs). WMSDs are discussed in  Chapter 13 .

All of the components within the workspace (e.g., chair, desk, keyboard) must be balanced.  Figure 4.2  provides an example of an ideal typing position.

Figure 4.2  Example of good sitting posture (Permission from Marci Merrick)

General Considerations

The key points of interface between the office worker and the office environment are as follows:

· The eyes and the visual display terminal (VDT) screen

· The hands and the keyboard

· The back, the legs, and the chair

· The feet and the floor.

We will talk about each of these key points and some suggestions on how to improve the comfort and efficiency for the office worker a little later in this chapter.

There is no optimum posture while sitting, the next posture is the best posture. Instead, the goal is to have the ability to shift your body by raising and lowering the position of the chair. You need to move around, changing how you sit as your body tells you to move. Ensure a person can attain a posture in which the ears line up over the shoulders and hips. The hip joint and knee joint should be at a 90–110° angle. Avoid slouching postures.

A poor sitting position may lead to the following:

· Neck and shoulder fatigue

· Low back pain

· Numbness and discomfort in the legs.

Ergonomic Stressors Associated with Computer Use

Let us think about the physical and contributing risk factors and which apply to computer use.

First, the physical risk factors associated with computer use are as follows:

· Awkward postures (hands, arms, wrists, neck, shoulder, and legs)

· Static muscle loading

· Repetition

· Contact stress (thighs, arms, and palms)

· Duration.

The contributing risk factors associated with computer use are as follows:

· Inadequate recovery or rest

· Extreme temperatures – hot or cold

· Stress on the job

· Fatigue.

After looking at the risk factors, we can identify some of them in the office area. Steady typing involves heavy repetition with little opportunity for muscle recovery. Inadequate recovery leads to fatigue.

An improperly setup workstation can lead a computer user to exhibit poor postures. If these postures are sustained, there may be static muscle loading. Computer tasks can often be visually or mentally demanding, which are contributing risk factors. Stress and constant attention requirements are also contributing factors. A computer workstation can cause contact stress for the computer user on the thighs (from the chair), arms (from the chair or workstation edge), and palms (from the workstation or the keyboard tray) (Figure 4.3).

Figure 4.3  Bad workstation creates bad posture – twisted posture (Permission from Raghunath Kanakali)

The phone is another area of possible ergonomics stress. If phone use is frequent or sustained, a headset might be an option. Normal telephone operation often involves bending the neck for long periods. Avoid cradling your phone, as this tends to cause neck pain and headaches. Figure 4.4 illustrates poor neck and shoulder posture. Hands-free headsets are available and greatly reduce this hazard by allowing the head to remain straight. Figure 4.5 illustrates an example of a hands-free headset that eliminates risk factors.

Figure 4.4  Poor neck and posture while cradling the phone (Permission from Cheryl Wilhelmsen)

Figure 4.5  Example of a hands-free headset (Permission from Jennifer Flynn)

People are concerned with sitting in an office on a computer all day. Some of their concerns are eyestrain or computer vision syndrome. Eye fatigue or eye strain is among the most common problems experienced. The eyes are focused using muscles that can become overworked. Intensive visual tasks can lead to soreness, temporary blurring, headaches, dryness, and redness. According to the 2015 Digital Eye Strain Report released by the Vision Council, nearly one-third of adults (30%) spend more than half their waking hours (9+) using a digital device. About 72% of adults are unaware of the potential dangers of blue light to eyes. Blue light is light that appears while but is exposing the eye to hidden spikes in intensity at wavelengths within the blue portion of the spectrum. Light-emitting diode (LED) lights and compact fluorescent lamps can emit a high level of blue light, typically the wavelength starting at 400 nm, according to the vision council Hindsight is 20/20/20 report of 2015 (Council, 2015).

The symptoms most commonly associated with these digital devices are as follows:

· Eye strain 32.8%

· Neck/shoulder/back pain 32.6%

· Headache 24%

· Blurred vision 23.3%

· Dry eyes 22.8% (Council, 2015).

If these problems do not go away, one may need computer glasses and should visit eye doctor. Some things may be able to do to help alleviate some of these issues are as follows:

· Increase the font size on computer.

· People tend to pull the head forward to view smaller print that can strain both their vision and neck.

· Correctly position their monitor(s).

· Minimize screen glare.

· Wear the right glasses.

· Take a break.

· Giving eyes a rest can help reduce eyestrain and fatigue. OSHA recommends workers take a 10-min break for every hour spent on the computer. Focus eyes on objects at farther ranges or simply close them and rest them (OSHA).

Neck and back pain or discomfort in the upper back or shoulders is another common problem associated with working with computer stations. The Administrative Controls chapter provides some great stretching exercises and tips to help reduce neck and back fatigue. Again, the computer workstation needs to be properly set up for each individual.

The impact of digital devices varies with each generation. Kids born between 1997 and 2014 spend more than 3 h a day using digital devices, Millennials born 1981–1996 reported nearly 7 in 10 symptoms of digital eye strain, Gen-X born 1965–1980 reported 63% or 6 in 10 report symptoms of digital eye strain, where the Boomers born 1946–1964 reported 81% own a TV and 26% or one in every four boomers spend at least 9 h on digital devices a day (Council, 2015).

Digital devices are great, they help us connect with others and share and capture information, but users tend to fail to notice how many hours are spent on these devices, which can affect vision health starting at a very young age.

Office Ergonomics: Evaluating

There are several indicators that an evaluation is necessary:

· Person is observed sitting in an awkward posture.

· Elbows are not bent at a 90° angle.

· Wrists are deviated.

· Person is leaning forward.

· Person looks uncomfortable.

· Person's feet are not supported.

· Person has experienced a musculoskeletal injury or illness.

· Person complains of aches and pains.

· Person complains that the workstation is not comfortable.

If any or all of the above are observed, an ergonomic assessment is encouraged.

When conducting an evaluation of an office computer workstation, it is important to start with a good introduction. Employee cooperation is much improved if one conducts evaluations upon request.

It is important to record job factors. What is the employee's job title and what are their responsibilities. In order to identify possible causes or ergonomic stress, they need to know what the person does on a regular basis. We can record tasks as a percentage of the day or as a range of hours (e.g., filing, talking on the phone, photocopying).

If a workstation is shared, it needs to be adjustable and you should explain to the user how to set up the workstation for their use. If the workstation is not shared, you should be able to set it up for the user.  Figure 4.6  is a drawing of office furniture location within easy reach of the user.

Figure 4.6  Easy reach workstation

One should also record how much of the person's time is spent using the keyboard and mouse. Keyboard use of greater than 4 h/day should be thoroughly evaluated. Some people only use a mouse once or twice a day, in which case the mouse can be located almost anywhere. If the mouse is used throughout the day, it is important to evaluate its location and use. What percentage of time the worker spends on each task, the environment and arrangement of the office equipment, and the postures used during these tasks are key factors in arranging the workers' office area. Again, the goal is to minimize the incidents of WMSDs.  Figure 4.7  illustrates an example of a device that helps to adjust the workstation.

Figure 4.7  Use a deskalator to raise a low surface (Original art by Lee Ostrom)

Filing, writing, or adding machines are other possible areas of ergonomic concern. If the employee uses these or other tools with high frequency, their use should be evaluated.

WORKSTATIONS

You should record what type of workstation a person is using. One can create a quick drawing with items such as the monitor, keyboard, and phone to help you in making recommendations. Correct adjustment is one of the best methods of preventing employees from developing WMSDs. A fixed-height desk may require an adjustable-height keyboard, whereas an adjustable-height desk may just need proper adjustment. The shape of the desk may determine the type of keyboard tray recommended.

Reach

· The most critical and frequently used items should be placed directly in front of the user and accessible without flexing the body forward or fully extending the arms (i.e., the mouse and keyboard).

· All less frequently used items, (i.e., the telephone or note pads) should be within a comfortable reach zone. For example, with the arms fully extended but not flexing the body forward.

Figure 4.8  illustrates the optimal reach area and the reach envelope that is both desirable and undesirable. If the workstation is adjustable, then you want to adjust the chair height so that the person's feet are resting comfortably on the floor. Thighs should be parallel to the floor with the hips at the same height, or slightly higher than the knees.

Figure 4.8  Reach envelops while seated

Other things to consider are as follows:

· The most commonly used items are accessible.

· Always analyze office layout to see if items can be moved closer to the user.

· Analyze what tasks are being performed and the workflow.

· Remind employees to stand when accessing books stored above the desk.

· Housekeeping.

· A lack of organization or an abundance of personal items are delicate issues that should be handled with tact suggestions for improvement.

Chairs

Chairs are one of the most important tools in an office. They affect posture, circulation, and the amount of strain on the spine. A good chair will support the back without forcing a posture. Selecting a chair is a bit like selecting a pair of shoes, one size does not fit all.

The following are indications that a chair may be inadequate:

· The person is sitting on the edge of the chair.

· There is excess space around the person on the seat pan.

· The person completely fills up the seat pan.

· The chair is not adjustable.

· The person yells, “I hate my chair!”

Figure 4.9  illustrates an adjustable chair where feet are flat on the floor and hips and knees are parallel to the floor.

Figure 4.9  Adjustable chair

One should always have a person's feet resting comfortably on the floor. If the workstation is adjustable, adjust the chair until the person's feet are resting on the floor. If the workstation is not adjustable, they will need a footrest to help support the feet and the knees at 90° when necessary.  Figures 4.10  and  4.11  illustrate some examples of footrests.

Figure 4.10  Use a footrest, when feet do not touch the floor (Original artwork by Lee Ostrom)

Figure 4.11  Use an F-ring, when feet do not touch the floor (Original artwork by Lee Ostrom)

There should be 2 in. of thigh clearance under the desk and 2 in. of space between the front edge of the chair and the back of the knee (popliteal area). If there is too much space, the thighs are not fully supported, and the chair may be too small for the user. If the back of the knees hit the front of the chair, the chair may be too big for the user. To remedy this, adjust the backrest of the chair forward or back (or some chairs have a seat pan that adjusts forward and back).

Popliteal height is “the vertical distance from the floor to the side of the knee.” The worker sits with the thighs parallel, the feet in line with the thighs, and the knees flexed 90° (National Safety Council, 2012).

· Thighs should be parallel with the floor.

· Hips should be at the same height or slightly higher than the knees.

Remember, we always start the alignment of the worker with the feet flat on the floor. This helps align the rest of the body. The lumbar support should be positioned to support the lumbar area of the back (located in the small of the back above the waistband). The user's arms should be comfortably at his/her sides with the elbows at a 90–110° angle. The wrists should be completely flat to encourage blood flow and nerve conduction.

If the chair has armrests, it should be adjusted so that the arms are at a 90–110° angle without the user having to hunch over with shoulders or back (which may indicate armrests which are too low). Armrests should not prevent the user from getting close enough to the work surface. Oftentimes, armrests can be removed from the chair if they are not needed or interfere with normal tasks. Armrests are useful for resting, particularly if talking on the phone or reading, but should not be used for typing.

The seat pan should be horizontal or tilted gently forward. It is believed that a seat pan tilted slightly forward can help with lower back pain.

Micropostural changes are encouraged throughout the day to reduce static loading and encourage blood flow. Even a perfect chair is not appropriate for extended use.

A common cause of discomfort in the back and upper extremities is an improperly adjusted chair or a chair that is inappropriate for the task. It is very important to train employees on the proper adjustment of their chairs. One should be able to operate it and understand the options and adjustability features to perform their tasks efficiently. In short, the chair should be easy to use.

Because people come in different sizes and shapes, there is no one chair that is perfect for an entire user population. The best approach is to have vendor's loan chair samples and allow the employees to select their own chairs.

When you are considering a new chair, you should look at several different factors:

· Ergonomic factors (comfort and size)

· Adjustability (range and ease)

· Durability (cost, expected life, maintenance, etc.)

· Gliding force (ease of motion), tipping force (stability), and safety of adjustment (controls must not present hazards)

· Other features (armrests, casters, and footrests).

Figure 4.12  illustrates a good working station posture with an adjustable chair.

Figure 4.12  Good working posture with an adjustable chair (Permission from Jennifer Flynn)

Ergonomics Guidelines for Office Chair Selection

Chair design contributes to the comfort and productivity of the workers. The chair can be a critical factor in preventing back fatigue as well as improving employee performance and efficiency. People who sit for long periods of time run a high risk of low-back injury, second only to those who lift heavy weights (Demographics, 2014). Management, professional, and office workers accounted for 23% of injuries and illness involving days away from work. The back was the primary body part affected and working position was the second highest source of injuries (National Safety Council, 2012). To reduce this risk, the user must be able to sit and maintain the spine in a neutral posture. A properly designed and adjusted chair is essential to maintaining a neutral posture.

Some manufacturers are eager to label furniture and accessories “ergonomically correct” or “ergonomically designed”, much like food products are liberally labeled “all natural” or “new and improved”. In reality, a chair that meets the body type of one person might not fit the next. Therefore, what is “ergonomically correct” for one individual may cause injury to another.

Chair selection is best when based upon personal testing. People vary widely in their shapes and sizes, and manufacturers offer a range of sizes to meet these needs. The following chart contains key criteria to consider in chair selection. All adjustments should be made easily from the seated position.

Workers should use the chair in accordance with manufacturer's instructions and can contact their local Safety and Occupational Health office for additional information.

Note: Alternative seating such as exercise balls, ball chairs, and kneel chairs do not meet the minimum requirements below and are not considered acceptable office seating. The dimensions below are intended to fit 90% of the population, special accommodations may be required for petite or tall individuals (BIFMA, 1998).

Ergonomics Guidelines for Office Chair Selection

See table in Guide  Appendix B

Keyboard and Mouse Height

The keyboard and the mouse should be located at a height equivalent to the user's seated elbow height to allow the user to float naturally over the keys. The keyboard height and position affects their posture. The keyboard should be placed in a horizontal position:

1.  Directly in front of the operator.

2.  Sloped toward the operator at an angle of up to 15° from the horizontal.

3.  Mobile so you can shift the keyboard on the desk.

4.  The home row on the keyboard should be at ELBOW height. It should be located at a height that provides the elbows to be at a 90–110° angle.

5.  Wrists and hands should be straight (not arched).

6.  Shoulders relaxed and lined up with the hips.

7.  Arms relaxed at the sides.

Since we started with the feet, the elbows should already be at the same height as the keyboard (when the back is straight). The mouse should be directly adjacent to the keyboard. Again, the mouse is at the seated elbow height. We will discuss how to measure the seated elbow height in the workstation section below.

The goal for the wrists is to keep them in a neutral posture as much as possible.  Figure 4.13  illustrates a few deviations in the wrist and the problems associated with each one.

Figure 4.13  Wrist deviations

Wrist supports can help maintain the neutral position; however, they can be misused. Wrist rests are not generally recommended because they are used improperly. People use them as a parking place for their wrists instead of a resting place. In addition, keying while using wrist rests can increase pressure within the Carpal tunnel (up to 140%). If wrist supports are used, training in the proper use should be provided. The soft gel type is preferred over the hard plastic type. Figure 4.14illustrates a wrist rest.

Figure 4.14  Wrist rest

You can retrofit a fixed-height workstation with an adjustable keyboard tray. Every keyboard tray needs an arm (often purchased separately). This arm should have room for a mouse. A height-adjustable arm is easy to adjust and retract under the desk. Figure 4.15 shows a keyboard tray where the mouse can be slid from right to left. If possible, the keyboard tray should provide a negative tilt, swivel at the desk and the keyboard, and adjust to fit a sit to stand workstation. A keyboard tray with a ratchet mechanism and no knobs or levers can help people with disabilities or CTS. Stability is very important in a keyboard tray.

Figure 4.15  Mouse platform (Original artwork by Lee Ostrom)

Mouse

A mouse that is too high can cause discomfort in the neck, shoulder, or arm. Locating the mouse on the desk surface when the person is using a keyboard tray can cause over-reaching and contact stress to the underside of the arm. If there is no room next to the keyboard, a mouse bridge can be placed over the number keys to provide space for operating the mouse. This option is only feasible if the number keys are not used frequently. A separate mouse tray can also be attached to the desk. Figures 4.15–4.17 illustrate mouse platforms.

Figure 4.16  Another mouse platform (Original artwork by Lee Ostrom)

Figure 4.17  Mouse platform that can be attached to the right or left of the keyboard (Original artwork by Lee Ostrom)

The mouse should be sized for the hand, the user should feel comfortable, and the user should not have to fight with it. There are many sizes and shapes, both right and left handed, available today. You need to find the one that fits you. The mouse should be located at the same level as the keyboard and at a 90–110° angle, close to the body. You want to keep the wrists straight or slightly flexed. Figures 4.18–4.20 illustrate a few examples of input devices.

Figure 4.18  Input device – trackball (Original artwork by Lee Ostrom)

Figure 4.19  Input device – mouse (Original artwork by Lee Ostrom)

Figure 4.20  Input device – EvoluentTM VerticalMouse 4 (Permission from Evoluent)

MONITOR HEIGHT

The monitor should be located so the top of the viewing area is at or below eye level. Monitor height and distance is different if the user is wearing bifocals. This is discussed in more detail in the measurement section of this chapter.

The monitor should be directly in front of the worker, not to the side. If it is not directly in front, they tend to constantly tilt your head up and down, turning to the side, which may contribute to stiffness in the neck, back pain, and other strains.

The old rule of thumb is to place their monitor at approximately arm's length in front of you. This was before the advancement of the larger monitors. Some monitors are so large that if you followed this rule, it would be too close for viewing. The distance should be dependent on the size of their monitor, but they will know if it is too close or too far back due to either tilting forward to viewing the text or tilting backward because the text is too close. The monitor height should be equal to, or 20° below, the seated eye height in order to maintain a neutral head position. The mid-monitor should be about 4 in. below the line of sight. A monitor placed too high may lead to stiffness in the back or the neck, due to neck extension.  Figures 4.21  and  4.22  illustrate examples of monitors.

Figure 4.21  Flat screen monitor (Original artwork by Lee Ostrom)

Figure 4.22  Cathode ray tube (CRT) monitor (Original artwork by Lee Ostrom)

Ergonomics for Dual Monitors

Many computer workstations have dual monitors as computer programs become even more complicated and LCD monitors become more affordable. Dual monitors are very useful for engineering drafting programs, movie and graphics editing, and emergency response centers. Below are some simple ergonomic setup guidelines for using dual monitors.  Figures 4.23  and  4.24 illustrate dual monitor positioning.

Figure 4.23  A and B: Dual monitor left- and right-hand workstation positioning

Figure 4.24  Good example of a dual-monitor workstation (Permission from Jennifer Flynn)

Position the primary monitor directly in front of the computer user at approximately an arm's length away or at a comfortable viewing distance.

The primary monitor is the display where work is actually performed. Position the secondary monitor or monitors to the sides at about a 30° angle to the primary monitor. The secondary monitor is used to display computer libraries or items needed on an intermittent basis. Always follow proper ergonomic guidelines for setting up the overall computer workstation.

Measurements

If the workstation is adjustable, then after they have adjusted the chair height so the user's feet are resting comfortably, measure the person's seated elbow height. This measurement is taken with the person's hands resting in their lap and elbows at their sides. Measure from the floor to the bony point of the elbow. This is the seated elbow height, as illustrated in  Figure 4.25 .

Figure 4.25  Seated elbow height

Next, we measure from the floor to the middle of the home row of the keyboard. This is the keyboard height. In order to maintain the neutral posture with straight wrists, the keyboard height should be equivalent to the user's seated elbow height. When a person's elbows are at their side in a 90° angle with their wrists and arms straight, the keyboard should be located just underneath the fingertips, and the person should float over the keys.

If the workstation is not adjustable, then the user's chair should be adjusted so that the keyboard height is equivalent to the user's seated elbow height. This may require a footrest if the chair is adjusted up. For taller users, the entire desk may need to be raised up on blocks. A fixed height workstation can often be retrofitted with an adjustable height keyboard and/or monitor arm.

With the user sitting up straight, shoulders relaxed, measure the height from the floor to the corner of the user's eye. The distance from the floor to the top row of characters on the screen is the monitor height. The monitor height should be equivalent to, or 20° below, the seated eye height. The eyes naturally fall down so we can easily read what is below eye height. Anything above eye height requires the user to extend their neck for viewing. Monitor height may need to be adjusted for bifocal wearers depending on which part of the glasses they use for viewing.

In the work setting, sustained or repeated forward head position and trunk flexion increase the risk of developing spinal disorders.

Figures 4.26  and  4.27  illustrate a couple of bad workstation setups.

Figure 4.26  Poor chair – no adjustments and stationary armrests

Figure 4.27  Poor workstation (Permission from Alex Vakanski)

OTHER ENVIRONMENTAL FACTORS

Lighting

The lighting will affect the monitor placement. The following lists a few guidelines to follow when dealing with lighting:

· Adequate lighting should always be provided dependent on the task.

· The ambient lighting (which is the general illumination of a room) should be between 300 and 500 lx.

· Task lighting should be provided for difficult-to-read hard copies.

· Care must be taken that the task lighting does not cause glare on the monitor screen (e.g., a lamp at your desk).

· Generally speaking, in an office the monitor is a light; therefore, the ambient lighting can be kept low and task lighting used for specific viewing needs.

Some Useful Definitions

1. Illuminance – The amount of light falling on a work surface or task from ambient or local light.

2. Luminance – The amount of light leaving a surface, may be emitted or reflected.

3. Candela – Power emitted by a light source in a particular direction, weighted by the luminosity function (a standardized model of the sensitivity of the human eye to different wavelengths). A common candle emits light with a luminous intensity of roughly 1 cd. The candela is sometimes still called by the old name candle, such as foot-candle. Foot-candle is the illuminance on a 1-ft surface of which there is a uniformly distributed flux of 1 lm (lumen). This can be thought of as the amount of light that actually falls on a given surface. The foot-candle is equal to 1 lm/ft2. One foot-candle ≈ 10.764 lx. The name “foot-candle” conveys, “the illuminance cast on a surface by a 1-cd source 1 ft away” (OSHA).

4. Lumen – A measure of the power of light perceived by the human eye.

5. Lux – A measure of the intensity, as perceived by the human eye. 1 lx = 1 lm/m2. Lux is a derived unit based on lumen, and lumen is a derived unit based on candela.

6. Contrast – The ratio of the luminance of the object and the luminance of the background.

7. Glare – The sensation produced by luminance within the visual field that is sufficiently greater than the luminance to which the eyes are adapted to cause annoyance, discomfort, or loss of visual performance and visibility.

8. Direct Glare  –  Caused by one or more bright sources of light that shine directly into the eyes.

9. Reflected Glare – Caused by light reflected from an object or objects that an observer is viewing.

Glare

Glare appears as mirror images or white spots on their computer screen. It is the result of bright steady light or reflection, which creates distractions from work. Glare causes the operator's iris to contract and the eyes to squint. The amount of light entering the eye is reduced, causing eyestrain (Grandjean & Kroemer, 1997). Reducing glare can improve the quality of the lighting.

In order to reduce or eliminate glare:

· Position monitor at right angles from the windows.

· Focus task lights onto the documents directly, not on the screen or the operator's eyes.

· Install drapes or window coverings.

· Use a glare hood on top of the monitor, which prevents the light from above hitting the screen.

· Use a glare guard or glare screen.

The following evaluation form for task lighting is a useful tool in helping to select the proper task lighting. Use this form as a guide to help you choose the best form of task lighting for your office.

Cornell Task Lighting Evaluation Form (Hedge, 2004)

	Yes	No
1. Does the task light have an asymmetric reflector or lens? 2. Is the task light dimmable? 3. Is the task light flicker free? 4. Does the task light source provide a good color rendering (CRI > 85)? 5. Is the task light lamp/source long lived? 6. Is the task light source cold to the touch (e.g., compact fluorescent, LED)? 7. Is the task light source energy efficient (e.g., compact fluorescent, LED)? 8. Is the task light easy to move and reposition? 9. Does the task light stay in place after repositioning? 10. Does the task light provide adequate glare-free light for your work needs? Total

Noise

Noise is defined as “any disturbing sound” (Grandjean & Kroemer, 1997). The hardest noises to control in large office spaces are printers, copiers, and other workers' conversations. Many office areas today are cubicles, which do not block noise. The optimum noise level should be below 55 dB. There are several suggestions in reducing noise in the office:

· Turn down telephone ringers.

· Hold casual conversations and meetings in separate rooms.

· When on the phone try to direct voice away from coworkers.

· Sound-absorbing hoods can be provided for printers, which can deaden the noise emission by about 20 dB (Grandjean & Kroemer, 1997).

OFFICE ERGONOMICS: ADMINISTRATIVE CONTROLS

Unlike engineering controls that are physical changes to the office workspace, administrative controls are procedures and practices that limit exposure to stressors by control or manipulation of work schedule, or the manner in which work is performed.

Eleven tips for an ergonomic computer workstation are listed below (Hedge, 2014):

1. Use a chair with a dynamic chair back and sit back.

2. Top of monitor at eye level.

3. No glare on screen, relocate monitor or use shades to control glare.

4. Feet on floor or stable footrest.

5. Use a document holder, preferably in-line with the computer screen.

6. Wrists flat and straight in relation to forearms to use keyboard/mouse/input device.

7. Arms and elbows relaxed close to body.

8. Keyboard set equal to seated elbow height with feet flat on the floor.

9. Center monitor and keyboard in front of you.

10. Use a stable work surface and stable (no bounce) keyboard tray.

11. Take frequent short breaks (microbreaks).

What About Using Laptop Computers?

Laptops have become more affordable and many people have turned to using them in place of the traditional home or office computers. Because of the design of the laptops, it actually violates a basic ergonomic requirement for a computer, namely that the keyboard and screen are separated. When the personal computing desktop devices were integrated (the screen and keyboard) into a single unit, it resulted in widespread complaints of musculoskeletal discomfort. By the late 1970s, a number of ergonomics design guidelines were written, and all called for the separation of screen and keyboard. The reason was simple. With a fixed design, if the keyboard is in an optimal position for the user, the screen is not, and if the screen is optimal, the keyboard is not. Consequently, laptops are excluded from current ergonomic design requirements because none of the designs satisfy this basic need. This means that one need to pay special attention to how use their laptop because it can cause problems. They need to ask oneself what type of laptop user am I? Do I use it occasionally for short periods, or do I use it all of the time as my computer? Full-time users may experience more problems.

The posture when using a laptop is a trade-off between poor neck/head posture and poor hand/wrist posture. For the occasional user, because the neck/head position is determined by the actions of large muscles, you are better off sacrificing neck posture rather than wrist posture. There are a few things one can do to help the posture:

· Find a chair that is comfortable and that one can sit back in.

· Position laptop in their lap for the most neutral wrist posture that one can achieve.

· Angle the laptop screen so that one can see this with the least amount of neck deviation.

· If one use the laptop computer as your full-time device, then these are a few things can do to help alleviate the bad posture:

· Position the laptop on their desk/work surface in front so that one can see the screen without bending your neck. This may require that you elevate the laptop off the 

· desk surface using a stable support surface, such as a computer monitor pedestal.

· Use a separate keyboard and mouse connected directly to the laptop or docking station.

· Use the keyboard on a negative-tilt keyboard tray to ensure wrist is in a neutral posture.

· Use the mouse on an adjustable position mouse platform (Hedge, 2004).

Many laptops offer large screens (15 in. plus) and can work as desktop replacements (giving the viewing area of a 17 in. monitor). However, think about where you will most use laptop to help you choose the best size. The larger the screen, the more difficult it will be to use this in mobile locations (e.g., airplane, car, train). On the other hand, the smaller the screen, the harder it is to see the text and this may cause eyestrain. One also need to consider the weight of the device and the accessories you need, such as the power supply, spare battery, external disk drive, zip drive, CD_RW. Many lightweight portables can become as heavy as regular laptops when you add the weight of all of the components together. A good rule of thumb is, if laptop and the components weigh 10 lb or more, then they should certainly consider using a carry-on bag with wheels. If they want a smaller bag and can comfortably carry laptop, consider a good shoulder bag.  Figure 4.28  illustrates a good example of proper posture when using a laptop computer.

Figure 4.28  Proper posture for using a workstation (Permission from Raghunath Kanakali)

SELF-GUIDE FOR CONDUCTING AN OFFICE ERGONOMICS ASSESSMENT

General Information

When conducting an office computer workstation evaluation, it is important to start with a good introduction. One should always start by introducing and asking the employees if they know what ergonomics is and why an evaluation is being conducted. This is a good place to use they succinct definition. A computer workstation evaluation checklist can be found in the guide  Appendix B .

Ask the employees if they are having any problems or concerns that prompted them to request an evaluation.

Always ask the employees if they are experiencing any pain or discomfort. If you know where they are hurting, you can better assess what part of the workplace may be causing or aggravating their symptoms. Unless you are a physician, you should never try to diagnose an employee or cast doubt on a diagnosis they have already received.

One should always make sure the supervisor is aware of an evaluation before you enter the work area. Their evaluation can always be used in legal proceedings, please watch what and how you record.

One should never assert that this workstation caused a person's medical conditions. It may put them at risk of WMSDs or aggravate an MSD, but it is very difficult to substantiate a direct cause-and-effect relationship. If the employee gives personal information or asks you not to disclose a medical condition, do not record it. Always be courteous, establish a good rapport, listen well, and take good notes.

Step One: Workstation

For notes, one should record what type of workstation a person is using. A quick drawing, noting where items such as the monitor, keyboard, and phone are located can help when they are writing their recommendations. A fixed-height desk may require an adjustable-height keyboard, whereas an adjustable-height desk may just need proper adjustment. The types of questions one should ask are as follows:

· What type of workstation does the employee have?

· Is it a fixed-height or an adjustable-height workstation?

· Is it a corner desk, an L-shaped desk, or a straight desk?

· Where are the keyboard, mouse, and monitor located?

· Where is the lighting?

· Where are the most commonly used items? (Telephone, reference books, etc.)

Step Two: Adjust the Chair

If the workstation or the keyboard tray is adjustable, start at the bottom with the person's feet. Correct adjustment is one of the best methods of preventing employees from developing WMSDs.

· Adjust the seat height, so the user's feet rest comfortably on the floor.

· Thighs parallel to the floor.

· Hips at the same height, or slightly higher than the knees.

· If the seat pan depth is adjustable, it should be adjusted to allow for 2–3 fingers to fit between the edge of the chair and the backs of the knees.

· If the seat pan tilts, it should be horizontal or gently tilted forward.

· The seat backrest should be adjusted so that the lumbar area of the back is supported (retain natural curve).

· If the armrests can be adjusted up and down, they should support the arms at a 90–110° angle without hunching the shoulders or bending the back.

· If the armrests get in the way, remove them or put them all the way down.

· The chair should have a stable five caster base with appropriate casters for the floor.

· The chair should be large enough to allow the worker to make micropostural changes throughout the day.

Step Three: Work Surface

· Is there adequate clearance beneath the workstation for the user to get close enough to the task, and not contact obstructions?

· Are the monitor and keyboard in alignment (directly in front of) the user?

If the workstation is adjustable, after they have adjusted the chair height so the user's feet are resting comfortably, measure the person's seated elbow height. This measurement is taken with the person's hands resting in their lap and elbows at their sides. Measure from the floor to the bony point of the elbow.  Figure 4.29  illustrates the seated elbow height.

Figure 4.29  Seated elbow height

Next, measure from the floor to the middle of the home row of the keyboard. This is the keyboard height. In order to maintain the neutral posture with straight wrists, the keyboard height should be equivalent to the user's seated elbow height. When a person's elbows are at their side in a 90° angle with their wrists and arms straight, the keyboard should be located just underneath the fingertips and the person's wrist should float over the keys. The mouse should be located at the same height as the keyboard and adjacent to the keyboard.  Figure 4.30  illustrates the seated keyboard height.

Figure 4.30  Elbow height = keyboard height

If the workstation is not adjustable, then the user's chair should be adjusted so the keyboard height is equivalent to the user's seated elbow height. This may require a footrest if the chair is adjusted up. For taller users, the entire desk may need to be raised up on blocks. A fixed-height workstation can often be retrofitted with an adjustable-height keyboard and/or monitor arm.

If the monitor is also on a fixed-height desk, then adjust the monitor after the chair height is adjusted so that Monitor Height = Seated Eye Height (or slightly below), if corrective vision is not used (You can remove the CPU or other items to decrease the height or add the CPU, monitor risers, monitor arm, or phone books, etc., to increase the height).

With the user sitting up straight, shoulders relaxed, measure the height from the floor to the corner of the user's eye. This is the user's seated eye height.

The distance from the floor to the top row of characters on the screen is the monitor height. The monitor height should be equivalent to or 20° below the seated eye height. The eyes naturally fall down so we can easily read what is below eye height. Anything above eye height requires the user to extend their neck for viewing. Monitor height may need to be adjusted for bifocal wearers depending on which part of the glasses they use for viewing.  Figure 4.31  illustrates the monitor height.

Figure 4.31  Monitor height = seated eye height

Step Four: Other Equipment

Telephone headsets are recommended for employees who are on the phone for extended periods or receive frequent calls. They are important for people who write or use the computer while talking on the phone. These people tend to cradle the phone with an awkward neck posture. Shoulder rests are less expensive but still cause an awkward neck posture and are not recommended for heavy phone use.

Document holders are useful for people that type from documents. Documents placed flat on the desk require the user to repeatedly glance from the horizontal surface to the monitor, which creates repetitive neck motions. The document should be placed at the same distance as the monitor as close as possible, unless the font is small.

Depending on the employee's tasks, certain items may decrease repetitions or improve posture:

· Ergonomic staple remover

· Automatic stapler or hole punch

· Box cutter

· Ergonomic pens

· “Y” connector for two input devices.

Step Five: Administrative or Behavioral Improvements

Some vision-related work habits to keep in mind:

· 20/20 Rule – refocus eyes for 20 s every 20 min.

· Blink/refocus eyes regularly.

· Keep the monitor screen clean (most dry/itchy eyes are a result of dust on the computer monitor).

· Regular vision care can help reduce eye strain.

It is very important to get the blood circulating and muscles moving throughout the day.

Step Six: Conclusion of Assessment

Make sure the employee knows the following:

· Where to go for additional information?

· How to get in touch with questions?

· Where to report pain or discomfort associated with his/her job?

· What to expect from the evaluation (report, follow-up, etc.)?

Thank the employee for their time.

What about Sit–Stand Workstations?

Cornell University conducted a study with participants using height-adjustable workstations. The results of this study suggested there were substantial decreases in the severity of upper body musculoskeletal disorder symptoms. One of the problems with standing workstations is when they raise the keyboard and mouse they also need to raise the height of the monitor or you start experiencing neck flexion discomfort. It seems there is also a greater wrist extension when standing, so people start to lean compromising their wrist postures. The overall conclusion is sit–stand workstations are cost–effective. It is best to sit while performing computer work using a properly set up workstation. The best thing is to stand and move for 2 min, every 20 min. Standing alone does not help, they need to move. The key according to Cornell is to build frequent movement variety into their normal workday (Hedge, 2004).

KEY POINTS

· One major problem with computer workstations is they keep an operator at that workstation in virtually the same posture all day long.

· The goal is to prevent musculoskeletal disorders by surveying the workplace.

REVIEW QUESTIONS

1. At what part of the body do you start your assessment?

2. How would you describe a neutral seated posture?

3. How do you measure the seated elbow height?

REFERENCES

1. BIFMA (1998). International Organization for Standardization 9241-5.

2. Case and Demographics. (2014). 2013 Nonfatal Occupational Injuries and Illnesses: Cases with Days Away from Work.

3. Grandjean, E., and Kroemer, K. (1997). Fitting the Task to the Human, A Textbook of Occupational Ergonomics 5th edn. CRC Press.

4. Hedge, A. (2004). Effects of an Electric Height-Adjustable Worksurface on Self-Assessed Musculoskeletal Discomfort and Productivity in Computer Workers. Cornell University Human Factors and Ergonomics Research Laboratory.

5. Hedge A. (December 06, 2014) 5 Tips for Using a Laptop Computer, Cornell University.

6. The Vision Council (2015). Hindsight is 20/20/20: Protect Your Eyes from Digital Devices.

ADDITIONAL SOURCES

Andersson, G. B. (1981). “Epidemiological aspects of low back pain in industry” Spine, 6(1).

OSHA.