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.

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.

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.

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.

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.

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.

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.

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.