Ergonomics Self-Tests

Question 1

What is the definition of ergonomics?

Answer 1

Ergonomics (or human factors) is the scientific discipline concerned with the understanding of interactions among humans and other elements of a system, and the profession that applies theory, principles, data and methods to design in order to optimize human well-being and overall system performance.

Question 2

Which fields contribute to the science of ergonomics?

Answer 2

Physiology, psychology, biomechanics, environmental studies, anthropometry, integrated with engineering programming, architecture, industrial design, and management sciences.

Question 3

What are the benefits of applying ergonomics?

Answer 3

Increased occupational health and safety, increased productivity and quality, system safety, improved return-to-work opportunities, and more effective training programs.

Question 4

What are the components of the user-task-environment model? Give examples of each.

Answer 4

The user — The person(s) in the system differ from each other and differ in various environments. The range of capabilities needs to be considered. Examples include: eyesight, hearing, strength, decision making ability, age, size, cultural background.

The task — All of the functions and processes which are undertaken within the system. This includes processing of information and products. Both inputs and outputs can be information or physical components. Examples include: physical demands of the task (force required, repetition, awkward postures), mental demands (workload, time pressure, control over work), social factors (social interaction, conflicts).

The environment — Includes physical (noise, vibrations, climate, lighting), learning (training, user manuals) and organizational (work/rest schedules, shift work, schedule supervisory styles) environments.

Question 5

Why is the user-task-environment model useful?

Answer 5

The user-task-environment model is useful because it provides a framework to ensure that all the important parts of the system, and the corresponding components, are considered in an ergonomics analysis.

Question 6

Why is a system design process so important?

Answer 6

Systems are increasingly complex and the performance of each component can only be properly assessed in the context of the whole system.
A systems approach will minimize errors and overruns and will keep projects on time and on budget.

Question 7

Why is user participation so important when (re)designing a system?

Answer 7

Knowledge: Existing users have the best knowledge of the way the system works for or against them. However, be cautious of users’ biases.
Validation: Users can validate a system solution by testing it in a real life situation. Validation must include typical users in order to ensure positive results.
Acceptance: Users are more accepting of a change to

Question 8

A system may have several functions. A function can be defined as:

Answer 8

What has to be done if the system is to fulfill its goals.

Question 9

Outline three different measures that can be used to assess an organization’s need for ergonomics.

Answer 9

Injuries — determine incidence rates and severity rates, investigate first aid records and nurses’ visits, conduct body part discomfort surveys
Production — measures of production rate, quality, customer satisfaction
Job satisfaction — worker questionnaires and interviews, discussions with managers and supervisors.

Question 10

List three ways to determine whether tasks are critical and need to be investigated further.

Answer 10

Human performance of the tasks might affect system performance.
They are tasks most frequently performed.
They are tasks related to individual or system safety.

Question 11

Describe the two different types of risk controls and give two examples of each.

Answer 11

Two types of risk control strategies include:

Engineering controls involve changes to the workstation, equipment, and tools which are permanent. Examples include: a modification to a workstation to adjust it to the correct height, and purchase of a hand tool which fits 99% of the user population.
Administrative controls involve changes to the way jobs are designed and organized. Examples include: job rotation and changes to shift work schedules.

Question 12

What is the time to payback investment calculation?

Answer 12

Implementation $ / (Injury$ * Injury#/year)

Question 13

Describe four different ways that the measurement technique will alter the final measurement value.

Answer 13

Time of day—Stature and sitting height are taller at the beginning of the day, since people can shrink up to ¼” over the course of a day. Girths are larger at the end of the day due to swelling.
Clothing—Shoes or winter clothing will add to the end value.
Slumped or erect—If the measure is taken in a slumped posture, stature and sitting height will be reduced.
Start and end points—The exact anatomical locations used to make the measurements may differ between anthropometrists, so make sure to refer to definitions and accompanying diagrams.

Question 14

What sort of considerations should be given to choosing an anthropometric guideline?

Answer 14

Coverage
Ethnic origin
Age of the group surveyed
Screening criteria
Age of the survey
Measurement techniques used
Dimensions measured
Clothing
Sample size

Question 15

Describe the seven steps to applying anthropometric data.

Answer 15

1, Determine task activity
2, Determine relevant body dimensions
3, Define target population
4, Select percentage to accommodate
5, Choose a database
6, Determine clothing factors
7, Determine critical values

Question 16

Which percentile cut-off would you choose when designing the height of a work bench?

Answer 16

When choosing a percentile cut-off for the height of a work bench, I would try to accommodate as many people as possible and use an adjustable height workstation. That’s not always possible, so perhaps having multiple work benches of different heights might be possible. If neither of those options are possible and you have to choose a single height, you have a couple of options. One approach is to accommodate shorter people by using steps of different heights to raise the person to the correct working posture. In that case I would choose the 90th percentile as a cut-off. The 10% who would be taller would stoop slightly. Another approach is to set the cut-off at the 50th percentile and use a step for shorter people and a table-top stand for taller people. In the end you have to look at how people are interacting with the work bench and the totality of the workplace.

Question 17

List five factors of the visual field.

Answer 17

Viewer position
Line of sight
Viewing distance
Viewing angle
Number of sources

Question 18

What postures should be considered when assessing a user’s access to task materials and equipment?

Answer 18

Both static and dynamic postures

Question 19

Describe the three work zones.

Answer 19

Primary zone—the area within easy reach that extends from the elbows to the finger tips when the elbows are bent at 90 degrees

Secondary zone—the area beyond the primary zone that extends from the elbow to the finger tips with the arms outstretched

Reference zone—the area beyond the secondary zone that extends beyond the finger tips with the arms outstretched

Question 20

Describe the three stages when involving users when designing a workspace layout.

Answer 20

Focus groups
Rough outline
3D layout

Question 21

What kind of information is represented in a link analysis?

Answer 21

A link analysis describe how different elements of a system communicate or interact. Links can show communication or movement patterns.

Question 22

List four features of an MSD.

Answer 22

MSDs arise from mechanical stress on the muscle and tendons.
MSDs arise from a physiological response to hormones and endorphins that changes the way the tissue responds to mechanical stress.
The development of the disorder is proportional to the intensity and duration of work.
MSDs may take weeks, months, or years to develop.
MSDs are poorly localized, often reported as diffuse pain, non-specific, and episodic.

Question 23

Describe four types of upper-limb MSD, and list a specific example of each type.

Answer 23

Muscle pain—Localized muscle fatigue occurs in many occupations as a result of extended static contractions or repeated dynamic contractions. For example, tension neck syndrome is caused by muscle pain in the neck resulting from holding the head in a tilted position for extended periods of time.
Tendon disorder—Tendon disorders most frequently occur near the joint, where the tendon rubs nearby ligaments and bones. For example, tendinosis refers to degeneration of the tendon’s collagen in response to chronic overuse.
Nerve disorder—Nerve disorders occur when the nerves become compressed due to external pressure from hard edges, or internal pressure as a result of swollen tissue. For example, carpal tunnel syndrome is the result of pressure on the median nerve, and results in tingling and numbness in the middle finger and half the ring finger, and very painful hands and wrists.
Neurovascular disorder-Neurovascular disorders involve both the nerve and the adjacent blood vessels. For example, thoracic outlet syndrome refers to the nerves and arteries in the neck become compressed between the neck and the shoulder as a result of an elevated shoulder held in a static contraction for a period of time.

Question 24

What are three factors that affect the torque on the back when lifting an object from the floor?

Answer 24

the weight of the object
the weight of the upper body
the distance to the center of gravity of the object from the back

Question 25

What physiological responses can be measured and used to indicate the physiological stress experienced as a result of a manual materials handling (MMH) activity?

Answer 25

increased heart rate
increased blood flow for each heart beat (the stroke volume)
increased blood pressure
increased metabolic rate (the rate at which we burn energy)

Question 26

Describe the three major types of low back pain. Which type is most common?

Answer 26

Fractures
Muscle strains and ligament sprains *most common
Disc injuries

Question 27

What are the three biggest task risk factors in the development of MSDs?

Answer 27

The three biggest risk factors are repetition, force, and awkward posture. Mechanical stress is not as common as the other three task risk factors.

Question 28

The most critical dimension of a container for increasing the force on the spine is:

Answer 28

The depth of the container.

Question 29

Which physical environmental factors are significant in the development of MSDs?

Answer 29

extreme temperatures (hot and cold)
vibration (hand-arm and whole body)

Question 30

Describe how whole-body vibration increases the risk for low back injuries.

Answer 30

Whole-body vibration can increase the metabolic needs of muscles, resulting in fatigue. It has also been shown to cause physiological changes in intervertebral discs over time.

Question 31

How do psychosocial stressors impact the development of MSDs?

Answer 31

The mechanism for psychosocial risk factors appears to be stress. As workers become more stressed, they tend to work more quickly and hold more tension in their muscles and tendons, thereby increasing tension in the tissue. There may also be an endocrinological response, whereby stress releases chemicals from the brain which modulate people’s pain experience and mechanical response to risk factors.

Question 32

What is the role of a checklist in the risk-identification process? What should it not be used for?

Answer 32

A checklist should be used as a reminder to an informed person to prevent them from overlooking an important aspect of the job. It should not be used as an assessment tool or a guideline from which to design a workstation or job.

Question 33

Describe the force estimation technique for grip strength.

Answer 33

Force estimation technique requires a hand-grip dynamometer, which measures grip strength in a power grip, or a pinch force gauge, which measures pinch gripping force. To complete the technique, the worker is asked to think about the force they are using to conduct the task, and then to replicate that force when they squeeze the dynamometer. This is repeated, usually about 3 to 5 times, until the measure on the dynamometer is consistent. An estimation of the required force can then be obtained and compared to available guidelines.

Question 34

What tools are used to measure joint angles directly and indirectly?

Answer 34

A goniometer and a protractor.

Question 35

For what types of activities is a biomechanical approach to risk assessment appropriate?

Answer 35

A biomechanical risk assessment approach is best suited to infrequent exertions with heavy loads.

Question 36

For what types of activities is a physiological approach to risk assessment appropriate?

Answer 36

A physiological risk-assessment approach is best suited to high-frequency exertions with light loads.

Question 37

For what types of activities is a psychophysical approach to risk assessment appropriate?

Answer 37

Psychophysical approaches have good sensitivity for situations of short duration, lower force, and/or fewer repetitions, because the test subjects during the trial have to extrapolate their judgement of effort from a short period to an entire working day.

Question 38

What is RULA and what is it useful for?

Answer 38

RULA (Rapid Upper Limb Assessment) is a technique whereby a moment in time can be analyzed to determine the severity of a combination of risk factors. It takes into account upper limb posture, force exertions, and muscle use or repetitions.

The first step in RULA is to select a high-risk posture from the activities on the task description. The posture observed is recorded on a worksheet, and the posture, force, and muscle-use factors are scored based on criteria given on the worksheet. A final severity score is found in order to determine the action level. Action levels above seven require immediate attention, while those that are lower are less urgent.

RULA is best applied to tasks characterized by static postures with lower concern for force and repetition factors.

Question 39

What are the similarities and differences between the ACGIH HAL-TLV method and the Strain Index?

Answer 39

Similarities

Both methods

assess the level of risk of injury to the upper limb
apply to monotask jobs
provide two limit values
do not incorporate all risk factors
Differences

ACGIH HAL-TLV uses two parameters: hand activity level and normalized peak force
Strain Index uses six parameters: intensity, exertion duration, efforts/minute, hand/wrist posture, speed, task duration (Revised Strain Index uses 5 parameters: intensity, frequency, duration, posture, hours)

Question 40

Which risk assessment tool can be used to assess a team lifting task?

Answer 40

MAC (Manual Handling Assessment Charts)

Question 41

Describe two engineering control measures for lifting-related injuries to the back.

Answer 41

assistive aids, such as a crane, vacuum lift, or forklift minimize the force required by the worker to lift the load
dividing the load into two smaller loads
providing handholds on the load to make it easier to lift the load
placing the load between knuckle height and shoulder height using, for example, lift tables, angled containers, or arranging the workstation height between knuckle and shoulder height to minimize bending
organizing the workstation so the worker can get close to the load to minimize reaching

Question 42

Describe two administrative control measures for a repetitive task involving the upper limb.

Answer 42

instituting a job rotation scheme that stresses different body parts
increasing the number of tasks performed so that the cycle time changes to lower the risk of injury
organizing work to achieve a constant work flow and avoid peaks in productivity
assigning more workers to the task
scheduling multiple, shorter rest breaks throughout the shift
allowing workers to set their own work pace, rather than be controlled by a machine

Question 43

Name two points that must be considered for job rotation programs to be successful.

Answer 43

The jobs should stress different parts of the body, rotating between lifting jobs, for example, or between hand-intensive tasks will not be helpful.
Increased training will be required so that employees are trained to perform several tasks rather than just one.
Cooperation with a union may be required so that seniority rights are not ignored.

Question 44

How does the type of work that is being performed affect the appropriate height of a work surface?

Answer 44

The appropriate height of a work surface is affected by the amount of force applied in a task. For precision work, the work surface height should be two to four inches above elbow height. For tasks which require application of force, the workstation should be four to five inches below elbow height.

Question 45

Describe four features that should be consider when choosing a tool that will reduce the chance of developing upper-limb MSDs.

Answer 45

handle diameter
grip span
grip type—a power grip is preferred
handle length—long enough to extend past the widest part of the hand
spring-loaded return
handles with cushioning, non-slip coating, no sharp edges, and no finger grooves
design that allows neutral posture in the upper limb
design that allows use of dominant hand or either hand

Question 46

What is one type of PPE that has not been conclusively shown to reduce the incidence of injuries?

Answer 46

Neither wrist braces nor back belts have been shown to prevent injuries. Also anti-vibration gloves generally do not protect workers from the harmful vibration frequencies.

Question 47

Which four critical elements should be part of a medical management program?

Answer 47

Passive health surveillance
Early reporting of symptoms
Prompt review of medical records
Plant walk-throughs by medical staff

Question 48

How is office work changing, and how does this change impact the worker from an ergonomics perspective?

Answer 48

Technology has driven extensive changes in the way office work is conducted. The offices of today have very different types of equipment, such as laptop computers, tablets, smart phones, and voice recognition systems. Non-traditional office environments such as an at-home office, an Internet café, or a vehicle have changed the way people work and the kinds of furnishings and job design required to support them.

Question 49

List three user factors that are relevant in office ergonomics and briefly describe how they are relevant.

Answer 49

anthropometry
visual acuity
age

Question 50

List four task factors related to office ergonomics.

Answer 50

prolonged work — can lead to visual fatigue
static contractions of the back muscles from sitting
awkward postures of the neck, shoulder, and back
force on the structures of the back and upper limb
mechanical stress on the wrists
repetition at the fingers and hands from typing and/or texting

Question 51

What types of environmental issues are present in an office environment? Provide an example for each.

Answer 51

visual — e.g., glare
chemical and biological — e.g., emissions from new carpet, standing water in the air conditioning system
thermal —e.g., low relative humidity
organizational —e.g., increased workload
psychological —e.g., lack of control

Question 52

For which type of tasks is an “L-shaped” workstation best suited for?

Answer 52

Jobs involving two distinct tasks.

Question 53

In general, how many degrees below eye height should the top line of text on a monitor be?

Answer 53

15°

Question 54

List three engineering control measures for improving visual environment.

Answer 54

increase task lighting to raise illumination level
decrease glare
exploit natural lighting
install incandescent lighting to avoid flicker

Question 55

Describe two ways to reduce glare in an office.

Answer 55

VDTs should be placed so that the screen is perpendicular to the window. This way, the worker does not look directly at a window (direct glare) and the sun doesn’t shine in over the workers’ shoulder and reflect off of the VDT screen into their eyes (indirect glare).
Decrease reflected glare by placing a hood around the screen or by using filters over the screen.
Use louvers on lights to direct light away from work surface and VDT.
Use lenses on lights to diffuse the light.
Use indirect lighting, which shines light onto the ceiling then bounces down into the room.

Question 56

Describe four of the eight factors which influence visual performance:

Answer 56

size
contrast
time
illumination
glare
flicker
colour
shadow

Question 57

Describe two administrative and two engineering control measures for lighting:

Answer 57

Administrative control measures for lighting include:

cleaning lamps, light fixtures, and room surfaces regularly
replacing lamps on a regular schedule before they are worn out
promoting regular eye exercises

Engineering control measures focus on three areas and include:

increasing illumination – Decrease the distance from the lamps to the work surface, exploit natural light, increase reflectivity, and direct light upward.
reducing glare – Reduce overhead illumination and add task lighting, orient workstations so that workers don’t face windows, install shades or curtains, use diffuse light sources, use low reflectance materials, use matte finishes, and reduce contrast between objects and their background.
minimizing adaptation – Increase illumination in an area immediately adjacent to bright areas, create an area of intermediate brightness, and ensure a clear path with no obstructions.

Question 58

Describe the two main types of hearing loss.

Answer 58

conductive - The apparatus that conducts sound energy to the inner ear is affected due to obstruction in the ear canal, blockage in the eustachian tube, damage to tympanic membrane, fluid in middle ear, or damage to ossicles.
sensorineural - The organ of Corti and/or the auditory nerve is affected by chronic exposure to noise.

Question 59

Describe two engineering control measures for addressing noise concerns.

Answer 59

control at the source - Change to a less noisy process, isolate noise source (machine), enclose noisy machines, provide doors or panels to allow access to machines, and maintain machines.
control along the path - Dampen noise sources, install partitions to confine noise, use sound-absorbing materials, and enclose workers.

Question 60

Two main types of personal hearing protection are?

Answer 60

ear plugs
ear muffs

Question 61

Describe one engineering control measure for hot environments and one administrative control measure for cold environments.

Answer 61

Engineering control measures for hot environments include:

increasing the distance between the worker and the heat source
shielding the worker from radiant heat source
using fans to increase air velocity
using dehumidifiers to decrease humidity
installing air conditioners to reduce air temperature

Administrative control measures for cold environments include:

promoting rest breaks in rewarming facilities
providing warm beverages for workers

Question 62

What does resonance frequency mean?

Answer 62

Resonance frequency is the frequency which increases the displacement of the object above that of the original vibration. It occurs at different frequencies for different objects and body parts.

Question 63

Describe two engineering control measures and two administrative control measures for whole-body vibration.

Answer 63

Engineering control measures for whole-body vibration focus on two areas, including:

control at the source - Maintain equipment and roads, and tune equipment so that it vibrates at non-hazardous frequencies.
control between sources – Add damping, use flexible connectors, isolate machines from surfaces that workers sit or stand on, anchor enclosure to the floor not the machine, and use good vehicle design.

Administrative control measures for whole-body vibration include:

preventative maintenance program
reduced driving speeds
job rotation

Question 64

What are the characteristics of a good coding system?

Answer 64

A good coding system should be:

detectable
discriminable
meaningful
standardized
multidimensional

Question 65

Describe two ways to improve working memory and two ways to improve long-term memory.

Answer 65

Working memory can be improved by:

paying attention to and rehearsing information
encoding information
chunking information

Long-term memory can be improved by:

keeping relevant information on display for the user
providing information that is conceptually compatible (matches the users’ mental model of how things work)
providing information that is movement compatible (matches the way the user expects things to move)
arranging the information so that it is spatially compatible (the associations among elements are readily apparent)

Question 66

In which situations is an auditory display a better choice than a visual display?

Answer 66

the person needs to respond quickly
the person moves around a facility rather than working in one place
the information is simple
the information is short
the information will only be referred to once
the visual system of the person is overburdened
the lighting in the environment is poor

Question 67

How could a link analysis be used in the design of controls and displays?

Answer 67

A link analysis could be used to determine the optimal layout of controls and displays, based on an analysis of importance, frequency, and sequence of use.

Question 68

List three guidelines for the use of colour on displays.

Answer 68

Limit the number of colours to four.
Avoid red and blue together.
Avoid red and green for small letters or symbols.

Question 69

Name four design guidelines to consider when arranging controls.

Answer 69

functional reach limits
grouped by function
sequence of use
adequate spacing

Question 70

What are some common reasons why ergonomics programs fail?

Answer 70

lack of management support
lack of behavioural modification
resistance to change
trying to implement too much too quickly
lack of belief in the program
a directive approach without employee involvement
poor training
poor implementation strategies

Question 71

Describe the three different types of ergonomics programs.

Answer 71

Some programs are developed to ensure that the organization is meeting its legislated ergonomics duties. Corporate commitment to the program may not extend beyond ensuring that the organization is not cited. In these cases, there tends to be very little knowledge about ergonomics within the organization. The main emphasis is “tell me what I need to do.” The aim of these programs is problem resolution, with a focus on major injuries, and the aim of retrofits rather than new design.

Other programs will rely on an expert with strong skills in ergonomics, who directs the organization through the ergonomics process. The organization will typically have few procedures in place and a very small skill base amongst its employees. This type of program works for small, single workstation interventions but is very difficult to sustain for the long-term in a proactive way.

A third kind of program is the most effective and self-sustaining type of program. This type of program involves widespread ownership of ergonomics within the organization, and includes procedures and policies and a broad skill base. The drive for ergonomics intervention comes from the employees. This is assisted with a framework to support their initiatives and an inherent understanding of the importance of the intervention to the operation of the organization. In essence, ergonomics becomes everyone’s job. The aim is prevention and attainment of best practices throughout the system.

Question 72

How might you go about justifying an ergonomics program?

Answer 72

To justify an ergonomics program, it is important to understand the organization’s business objectives and gear the justification to showing how the ergonomics program can fit in with the company’s vision. To justify the establishment of a program, injury and production data will first need to be gathered from:

first aid reports
medical and compensation costs
number of incidents and near misses
quality control measures
absenteeism
employee turnover

With this data, cost-justify the program by showing the payback resulting from a good ergonomics program. Previous case studies and comparison of cost of injuries versus cost of implementing solutions would be presented to prove that a program would be cost effective.

Question 73

Why is it important to have people from different departments on an ergonomics committee?

Answer 73

It is important to have representatives from many parts of the organization on the ergonomics committee because each of the stakeholders can provide relevant information, and participation by each can ensure everyone’s cooperation in assisting and facilitating the completion of the necessary projects.

Question 74

List the five stages of developing a successful ergonomics program.

Answer 74

1. Gain organizational commitment and involvement.
2. Plan for intervention.
3. Identify and assess risk.
4. Implement controls.
5. Monitor and evaluate.