3520 Flashcards
1
Q
Give an ergonomics anecdote for world war II wheels
A
World war II aircraft controls for wheels, had a design flaw. The wheels will lowered, when a lever was pulled. The wheels would then raised when the lever was pushed. This system was counterintuitive, and so many pilots lost their lives, thinking they had lowered their wheels when they had not.
The field of ergonomics was significantly established at the time due to issues of this nature in New technologies.
2
Q
What is the IEA?
A
The international ergonomics association
3
Q
What is the IEA definition of ergonomics?
A
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.
4
Q
What is the IEA definition of ergonomics?
A
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.
5
Q
Discuss ergonomics vs human factors
A
Ergonomics and human factors are often used as interchangeable terms.
Sometimes the terms “ergonomics” and “human factors” are used to describe different parts of an occupational system. People using the term “ergonomics” tend to emphasize the physical side of person-process interaction. Conversely, people using the term “human factors” tend to stress the perceptual and mental side. In fact, these two aspects are intertwined in any job and they should not be thought of separately.
6
Q
List 5 major and 5 minor fields of study (factors) that an ergonomist should integrate.
A
MAJOR
- psychological
- biomechanical
- environmental
- anthropometric
- physiological
MINOR
- engineering
- programming
- architecture
- industrial design
- management
7
Q
List 5 general benefits of applying ergonomic principles in the workplace.
A
- Increased occupational health and safety
- increased productivity and quality
- system safety
- improved return to work opportunities
- More effective training programs
8
Q
List 5 general benefits of applying ergonomic principles in the workplace.
A
- Increased occupational health and safety
- increased productivity and quality
- system safety
- improved return to work opportunities
- More effective training programs
9
Q
Define an objective, in the context of a systems approach to the workplace
A
An objective is a reason for the system to exist. The end goal, that the system should accomplish.
10
Q
Define limitations, in the context of a systems approach to the workplace.
A
The constraints within which the system must be developed or operated. These commonly include budget, time, and personnel. There may also be safety, geographical, and procurement (purchasing) constraints.
11
Q
Define functions, in the context of a systems approach to the workplace.
A
A function, is something that must be done for an objective to be achieved.
12
Q
Define interface, in the context of a systems approach to the workplace.
A
An interface is the way in which two or more components of the system interact to transfer information, power, or something else.
13
Q
Define input, in the context of a systems approach to the workplace.
A
Anything that goes into the system to make it work. (Information, power, people, equipment, materials)
14
Q
Define output, in the context of a systems approach to the workplace.
A
Anything that comes out of the system at the end of a process.
(A final product, information, power, people, equipment)
15
Q
Define feedback, in the context of a systems approach to the workplace.
A
A way to measure how well the systems objectives are being met.
16
Q
What are the 10 steps of a design cycle?
A
1, objectives and constraints
2, component capabilities/limitations
3, seperation of functions
4, allocation of functions
5, design options
6, task analysis
7, workstation design and layout considerations
8, system integration
9, design evaluation
10, post design evaluation
17
Q
What are the 10 steps of a design cycle?
A
1, objectives and constraints
2, component capabilities/limitations
3, seperation of functions
4, allocation of functions
5, design options
6, task analysis
7, workstation design and layout considerations
8, system integration
9, design evaluation
10, post design evaluation
18
Q
What are 4 aspects of human capabilities that ergonomics integrates?
A
Sensory
Cognitive
Physical
Social
19
Q
What is the user-task-environment model?
A
A model to classify the different components of a system.
This model illustrates how a person influences and is influenced by the overall system. This gives a framework to ensure all important parts of the system are considered.
-User factors
-Task factors
-Environment factors (physical, learning, and organizational)
20
Q
What are the 4 main categories of the physical environment that an ergonomist should consider?
A
Visual environment
Acoustic environment
Thermal environment
Vibration environment
21
Q
Why is a system design process important?
A
Systems are complex and the performance of a component must be assessed in the context of the whole.
A systems approach minimizes errors and keeps projects on time and on budget.
22
Q
Why is user participation important when designing/redesigning a system?
A
Knowledge
Users have valuable knowledge (caution for bias)
Validation
Users can validate system and may perform differently than an expert or designer
Acceptance
Worker buy-in
23
Q
List the components of a 7-step ergonomic evaluation process.
A
- Planning
(What are the objectives, what is your role, who are the other players) - Assessing needs
(Leading indicators & lagging indicators) - Background information
(Define job, tasks, activities) - Hazard/risk identification
(what are the risk factors) - Risk assessment
(how much risk is there with each factors & what is acceptable) - Risk controls
(Hierarchy, emphasis on engineering & administrative) - Monitoring
(review and compare to leading and lagging needs)
24
Q
List the components of a 7-step ergonomic evaluation process.
A
- Planning
(What are the objectives, what is your role, who are the other players) - Assessing needs
(Leading indicators & lagging indicators) - Background information
(Define job, tasks, activities) - Hazard/risk identification
(what are the risk factors) - Risk assessment
(how much risk is there with each factors & what is acceptable) - Risk controls
(Hierarchy, emphasis on engineering & administrative) - Monitoring
(review and compare to leading and lagging needs)
25
What are 3 major measurements that can be used to assess an organizations need for ergonomics?
Injuries
Production
Job satisfaction
26
List 3 determiners that indicate that a task is in critical need of ergonomic assessment.
Human performance of the task might affect system performance
The task is performed frequently
The task is related to individual or system safety
27
What is the time to payback investment formula for implementation of ergonomic programs?
Time to payback investment = (Implementation Cost) / (Injury Cost * Number of Injuries)
28
What is anthropometry?
The science of measuring human dimensions and applying the knowledge to the design and evaluation of products and workspaces for human use.
29
List the 7 steps for applying anthropometric data to the design of workstations or equipment.
1, Determine task activity.
2, Determine relevant body dimensions.
3, Define the target population.
4, Select the percentage of the population to be accommodated.
5, Choose the appropriate anthropometric database.
6, Determine clothing requirements.
7, Determine the critical value.
30
Describe the 7 steps for applying anthropometric data to the design of workstations or equipment.
1, Determine task activity.
- Sitting, standing? Reaching? Body movements? Equipment being used?
2, Determine relevant body dimensions.
- Sitting height vs statute vs elbow height. What dimensions are important? Consider static vs dynamic dimensions. ROM & Reach envelope.
3, Define the target population.
- Gender, ethnicity, age group
4, Select the percentage of the population to be accommodated.
- Typically 5th to 95th percentile (within 2SD of mean)
- Some cases are based on an extreme, such as the height of a doorway (99th percentile of men)
5, Choose the appropriate anthropometric database.
- Consider data source
6, Determine clothing requirements.
- Clothes & PPE may alter measurements by adding height/bulk or reducing ROM
7, Determine the critical value.
- The end value chosen
- This may be the value of the mean, or the 95th percentile
- The value may account for clothing or other factors
- A range may be chosen when designing for adjustability
31
What are the four main ergonomic design strategies?
- Design for the average
- Design for a range
- Design for extremes
- Design for adjustability
32
Identify two important aspects of anthropometry.
Measurements & Applications
Measurements, how to measure body dimensions and how guideline values are estimated.
Applications, how to use guidelines and lay out workplaces or select products.
33
Identify four types of dimensions that can be measured for anthropometric studies.
- Static dimensions
- Range of Movement
- Reach envelopes
- Dynamic dimensions
34
If a movement must be performed repetitively or with force, then what consideration should be given to the ROM?
Strength is greatest in the central third of any given ROM. Outside of this range, strength decreases and vulnerability to injury increases.
Any movements requiring force or repetition should be kept within the central third of the ROM.
35
What is a reach envelope?
A reach envelope is the 'bubble' within which a person can reach without moving their body. It is determined by the dimensions of the limb and ROM.
Reach envelopes should be used in workstation designs, but not all locations within the reach envelope are necessarily ergonomically sound positions.
36
What are dynamic dimensions in anthropometry?
Dynamic positions are similar to static dimensions, but involve the movement of different body parts.
Examples:
Static reach - the length of an extended arm
Dynamic reach - the reach of an extended arm while leaning forwards
Dynamic dimensions are greater than static dimensions, require more energy, and increase stress to the body.
The dynamic dimensions of two people with similar static dimensions can be very different.
37
Review bell curves, SD, percentages of populations, and Z-tables.
A bell curve is a normal distribution.
One SD is the variability from the mean that would include 68% of the population (34% either side of mean).
68% of population are within 1SD of mean
95% of population are within 2SD of mean
99% of population are within 3SD of mean
A z-table gives the area under a bell curve to the left of a Z score. It is used to identify the data value for any given percentage of a population.
38
Give examples of how a bell curve can be used to help in an ergonomics assessment.
When choosing the handle circumference of a tool, it is important that workers can grip it. Buying tools to fit the 5th percentile of workers will ensure the smallest hands can hold the tool. It may be small for the 95th percentile, but this might be acceptable.
When choosing adjustable workstations, it would be best if the adjustments can reach the requirements of the 5th to 95th percentiles.
39
List 4 ways that anthropometric measurement techniques will alter the measurement value.
- Time of day
- Clothing
- Slumped/erect
- Chosen start/end points of measurements
40
List 8 considerations when choosing an anthropometric guideline.
- Age/gender
- Geographic region
- Ethnicity
- Participant screening criteria
- Measurement techniques used
- Dimensions measured
- Clothing
- Sample size
- Age of survey data
41
What two user needs must be considered when planning a workspace layout?
Task Information (access to information to perform task)
Task Materials/Equipment (access to materials/equipment to perform task)
42
Ergonomic planning for visual task information should consider what 5 points?
- Viewer Position
Where will the worker be when they need the information. Make the visual information comfortably available at that location.
- Line of Sight
Natural line of sight is 15° below horizontal (top of monitor at eye level for middle of screen to be optimal). Note that bifocal wearers add another 15°.
- Viewing Distance
Distance to information must match size of information. If size cannot be changed, either change distance or use magnifiers.
Example, electronics are small and cannot be moved close enough for vision. Therefore use magnifiers.
- Viewing Angle
Often accuracy of information changes when viewed at an angle (a dial may look different when viewed from side). Ensure information is best viewed from the direction it is being viewed.
- Number of Sources
If multiple sources of information are necessary, they should be arranged to reduce side to side view changes. For example, put information in order to be viewed from left to right instead of left, right, then middle.
43
What are three broad topics to consider when planning for ergonomic access to task materials and equipment?
- Static & Dynamic postures
Muscle fatigue & lactic acid buildup with static postures. Allow for dynamic movement to reduce fatigue
- Reaches
Keep reaches within overhead and forward reaches (usually accounting for 5th percentile of females)
- Forces
Most strength at midpoint of ROM (90° elbow).
Force is weight, distance/reach, and duration.
44
List 7 rules of thumb for access to materials/equipment in workstation design.
1, Upright, facing forward, neutral posture
2, Equal weight distribution on both feet
3, Work performed between should and knuckle height
4, Minimize prolonged unsupported postures of any limb
5, Keep limbs around midpoint of ROM (+/-20%)
6, Make repeated movements possible with either limb
7, Allow for seated and standing options at user discretion
45
What are the four general layout principles to determine component location in a workspace?
- Frequency of Use
- Sequence of Use
- Importance
- Work Zones
46
What are the three workspace work zones?
- Primary Zone
Elbows to fingertip with 90° elbows
- Secondary Zone
Elbows to fingertips with extended elbows
- Reference Zone
Outside of reach
47
What is link analysis in the context of ergonomics?
Link analysis describes how system elements communicate & interact.
A tool to help optimize work stations/areas.
Identify the three link types:
- communication links
- movement links
- interactive links
Then draw the links on a plan of the area including frequency & sequence. Colour code the three link types and add identifier for importance.
This will visually capture the processes and help in redesign. Comparison link diagrams can be used to determine which layout is more efficient.
48
List 4 examples of work tasks where a seated workstation is recommended.
- Detailed/fine assembly work (including writing)
- Short-cycle tasks where all items needed are readily available in the normal work area
- Tasks where handling of items are below an average of 15cm above work surface
- Work requiring foot pedals/controls
49
List 5 examples of work tasks where a standing workstation is recommended.
- Workstations without knee clearance
- Tasks where out of range reaches are frequent
- Handling of heavy (>4.5 kg) objects
- Tasks where frequent movement between workstations is necessary
- Tasks where downward forces are predominantly applied to the work surface
50
List 2 examples of work tasks where a sit/stand workstation is recommended.
- Frequent extended reaches (40cm) forward, or 15 cm above the work surface
- Where the work includes elements that would recommend both a seated and standing work station
51
List 10 general principles for seating choices.
1, Elbows about 90 degrees.
2, Knee angles at or above 90 degrees.
3, Hip angles greater than 90 degrees.
4, Seat pan length less than smallest users femur
5, Wide enough for the widest hip, plus 25 mm for clothing.
6, Backrest supports lumbar curve and allows shoulder movement.
7, Adjustable seat slope.
8, Non-slip fabric.
9, Armrests only if practical and adjustable for users.
10, Five legs for stability.
52
What are the two general techniques for assessing workspace layout?
1, User involvement
2, Link analysis
53
What two postures should be considered when assessing a user's access to materials and equipment?
Static & dynamic postures.
54
What are the three stages of user involvement in workspace layout design?
Stage One - focus groups
(cross-section of users discuss potential design issues)
Stage Two - rough outline
(draw design options and have focus group identify concerns/priorities)
Stage Three - 3D layout
(mock model to allow users to get a feel for the workspace)
55
What is a WRMSD (injury type)
Work-Related Musculoskeletal Disorder
56
What is a CTD (injury type)
Cumulative Trauma Disorder
57
What is RSI (injury type)
Repetitive Strain Injury
58
What is an OOS (injury type)
Occupational Overuse Syndrome
59
What is an STI (injury)
Soft Tissue Injury
60
List 5 characteristic features of MSDs
- Usually poorly localized, diffuse, non-specific, episodic pain
- Caused by mechanical stress on muscles/tendons
- Caused by changes in hormones/endorphins that change the way tissue responds to mechanical stress
- Development of disorder is proportional to intensity and duration of work
- MSDs may take years to develop
61
List 4 reasons why the incidence of MSDs is so high.
- Many jobs are more task specific than they used to be with increased repetition. (worker may repeatedly do one process in a line, rather than all the processes)
- Increased awareness to identify MSDs in workers/employers/medical practitioners
- Aging workforce. Older workers are less physically resilient and have likely been doing the work a long time too
- More acceptance of MSDs with compensation boards
62
What is the carpal tunnel?
An area in the wrist containing tendons and the median nerve. Dorsal to this area are the carpal bones. Ventral/palmer to this area is the carpal ligament which is connected to the lateral/medial carpal bones.
63
Why do static contractions often result in fatigue quicker than dynamic contractions?
Muscle activity during dynamic contractions increases blood flow which provides oxygen and removes lactic acid.
A static contraction has less blood flow, and therefore less oxygen with more lactic acid.
64
Why is local pain and swelling a normal reaction to MSDs?
Pain and swelling force the sufferer to rest.
65
What are the four basic types of MSD involving the upper limb?
- Muscle pain
- Tendon disorder
- Nerve disorder
- Neurovascular disorder
66
What are the three important, major nerves in the upper limb?
- Ulnar nerve
- Median nerve
- Radial nerve
67
What is the cubital tunnel?
The area of the elbow where the ulnar nerve passes through. Similar to the median nerve in the carpal tunnel.
68
What is de Quervain's disease?
A tendinopathy at the base of the thumb impeding grip/pinch.
Caused by repetitive forceful hyper-extensions of the thumb (wide pinch grips)
69
What is Trigger Finger disease?
A tendinopathy of a finger tendon, often caused by repetitive use of a finger-trigger hand-tool.
70
What are Medial Epicondylitis and Lateral Epicondylitis?
Epicondylities is a tendinopathy at the epicondyle of the humerus (elbow).
Medial epicondylitis is Golfer's Elbow.
Laterial epicondylitis is Tennis Elbow.
71
List the cervical vertibrae in humans and dogs.
Humans:
C1-C7
T1-T12
L1-L5
S1-S5
Co1-2/4 (variable)
Dogs:
C1-C7
T1-T13
L1-L7
S1-S3
Co1-Co20/23 (variable)
72
What are the articulating parts of vertebrae?
Vertebral facet joints.
73
Which parts of the spine are more susceptible to injury?
C7 nerve roots - major nerves for the upper limbs.
L5-S1 nerve roots - major nerves for the lower limbs, including sciatic nerve.
Lumbar vertebrae - thinner ligaments protecting lumbar vertebrae than others.
74
Discuss the main considerations in Manual Materials Handling (MMH) related to lifting an object using your back vs legs.
Lifting with back puts more force on L5/S1 because
- increased distance/leverage
- Bending forwards adds weight of upper body to weight lifted
Lifting with legs creates greater fatigue
- Larger muscles have greater O2 demand resulting in increased HR/RR (pay back O2 debt/lactic acid)
- A full squat is slower than simply bending over
75
What is the most commonly reported MSD in the workplace?
Lower back pain.
76
Differentiate strains and sprains.
Strains are muscular or tendon injuries.
Sprains are ligament injuries.
77
List the four types of upper limb MSD and give a specific example of each.
- Muscle Pain
Tension Neck Syndrome is a MSD caused by holding the head in a tilted position for extended periods (telephone usage). Muscle fatigue from extended static contractions or repeated dynamic contractions.
- Tendinopathy
Tendinosis where there is degeneration of the tendon collagen from chronic overuse.
- Nerve disorder
Carpal tunnel syndrome, where median nerve is compressed by swelling of the carpal tendons.
- Neurovascular disorder
Both nerves and blood vessels involved. Static contractions with elevated shoulders can compress nerves and arteries in the neck.
78
What three factors affect the torque on the back when lifting an object?
Object distance from body axis
Weight of upper body
Weight of object
79
What physiologic measurements can be taken to indicate increased physiological stress with MMH (manual materials handling)?
Increased ...
HR
BP
Stroke volume
Metabolic rate
80
Summarize the three major types of lower back pain.
Muscle strain/ligament sprains
- Most common
- Single over-exertion or cumulative damage
- Overexertion or awkward postures
Disc Injuries
- Bulging discs or prolapsed disc
- Chronic, cumulative injuries can weaken outer disc
- Acute force can cause prolapse
- Discs can become degenerated/dehydrated over time increasing risk of injury or displacing vertebrae and putting pressure on nerve roots
Fractures
- Least common
- Usually traumatic
81
What type of problem typically causes neurogenic back pain?
- Bulging or herniated discs
- Spinal stenosis
- Bone spurs
Resulting in pressure or damage to nerve roots or spinal cord.
82
What type of problem typically causes mechanical back pain?
Direct injury to...
- Disc
- Facet joint
- Ligament
- Muscle
83
What are the 4 major task-specific risk factors for MSDs?
- Repetition
- Force
- Posture
- Mechanical stresses
84
Discuss Maximum Voluntary Contractions (MVCs)
The MVC is the maximum amount of force an individual can exert. It is used as a percentage.
Exertions >60% MVC should be avoided.
For frequent actions, exertions should be <30% MVC.
If a continuous action is required, then forces should be kept below 15% MVC.
85
How do the number of muscles change the risk involved in MMH?
The greater the number of muscles utilized in Manual Materials Handling, the lower the risk.
Example:
A pinch grip uses thumb strength. A power grip uses the whole hand. When lifting the same weight, the pinch grip has greater risk of causing a MSD.
86
In general, which has greater risk for MSDs? Pulling or pushing?
Pulling puts more strain on the spine than pushing, therefore pulling usually has greater risk.
87
What are four characteristics of a load that change the risk of a MSD when performing MMH?
- Weight of the load
(NIOSH recommends max lift/lower weights of 23kg)
- Dimensions of the load
Smaller and concentrated is better. Depth is most important with max of 50cm
- Hand couplings
Better hand couplings, lower risk.
Ideally handles should be 115mm long, 25-38mm wide, and 3/8 down the container.
- Stability
More stability = less risk. Fluids, uneven objects, and animate objects increase risk.
88
What is an awkward posture?
Any posture that deviates from the neutral range.
Deviating from a neutral posture increases strain on tendons because they are not working in a straight line.
89
How much load should be reduced when a lift involves a twisting motion?
The load should be reduced by 3% for every 10° of twisting.
90
What are mechanical stresses in MMH?
Mechanical stresses aka Contact Stress are:
Forces on tendons and nerves from contact with hard or sharp edges.
Examples:
- Ridges on a screwdriver against the hand.
- hard edge of desk on wrist
- floor against knee when kneeling
91
What are three important physical environmental risk factors for MMH?
The thermal environment
The acoustic/visual environment
Vibration
92
How does the thermal environment affect MMH as a risk factor?
Cold temperatures are linked to MSD, and can be caused by cold environments or the handling of cold materials.
Heat exposure influences internal physiology as well as psychology. Heat stress often causes irritability and carelessness.
93
How does the acoustic/visual environment affect MMH as a risk factor?
There is no research to demonstrate that the acoustic/visual environment decreases MMH capabilities.
Acoustic noise could impact balance.
Lighting can increase the risk of slips/trips/falls.
94
How do vibrations in the environment affect MMH as a risk factor?
Handling vibration tools cause damage to blood vessels and nerves. Exposure limits are set by ISO.
Whole body vibration (vehicles) is known to increase risk of back pain.
95
How does the organizational environment affect MMH as a risk factor?
- Distribution of higher risk MMH tasks
- Frequency of breaks and workload
- Return to work programs enabling workers to recover properly when returning to work
96
How does the phycological environment affect MMH as a risk factor?
Any cause of stress. Stress increases tension, decreases performance, and releases hormones that increase MSD risk.
- Monotony of work
- Job satisfaction
- Performance feedback
- Pressure
- Morale
97
Is gender a risk factor for MSDs?
Not really.
Men may typically have greater muscle mass, pregnancy may increase MSD risk factors.
Women have higher MSD statistics, but these are aligned with female-dominant professions where the work has an increased risk for MSD.
98
What are the three biggest risk factors for MSDs?
- force
- posture
- repetition
99
In MMH, what is the most critical dimension of a container for increasing the force on the spine?
The depth of the container.
100
Which physical environmental factors are significant in the development of MSDs?
Extreme temperatures
Vibration
(acoustic/visual are not known to be significant)
101
How does whole-body vibration increase risks for lower back injuries?
- Increasing O2 uptake
- Increasing cardiac output
- Chronic exposure causes physiologic changes to intervertebral discs
102
What is the role of a checklist in MSD Risk Identification?
A reminder for an informed person to prevent missing important aspects.
Checklists should not be used without full understanding. They should not be used as a guideline to design work.
103
List three measures that can be used to assess an organization's need for economics.
Injuries
Production
Satisfaction surveys
104
Differentiate jobs, tasks, subtasks, and activities in the context of an organizational system.
A job is a distinct set of tasks that must be completed to meet the overall objective of the system.
Tasks are elements of a job that must be performed to complete the job.
Subtasks are elements of a task that must be performed to complete the task.
Activities are the smallest unit of measurement, and are necessary to be performed to complete the job/task/subtask.
105
What anthropometric percentile cut off should be used for a workbench height?
Complicated & ideally adjustable.
Consider
- type of work
- seated vs standing
- ability to use step stools
- ability to use table-top stands
End options:
- 90th percentile with stools and 10% stooping
- 50th percentile with step stools and table-top stands
106
When considering ergonomic general layout , should important items or frequently used items be placed more centrally?
Important items should be more central.
107
List 5 general features of MSDs.
- Arise from mechanical stress on the muscle and tendons.
Arise from physiological response to hormones changing the way tissues react.
- Proportional to intensity and duration.
- May take weeks, months, or years to develop.
- Poorly localized, often reported as diffuse pain, non-specific, and episodic.
108
How do psychosocial stressors impact the development of MSDs?
- Tension in muscles
- Endocrine response
109
Why is a system design process so important?
Context, ergonomics.
- Systems are complex, and components need to be assessed in the context of the whole
- Structured approach to help reduce errors and keep projects on time and on budget
110
What is needed before an ergonomic risk assessment can be conducted?
A task description and task analysis are both necessary to perform an ergonomic risk assessment.
111
What are the four steps of an ergonomic Task Analysis?
1) Task Description
- tasks/subtasks/activities
- identify critical tasks
2) Overall Job Exposure Time
- Total shift time minus all breaks
3) Task Exposure Time
- Amount of time spent on each task
- Report in hours and %
4) Cycle Repetitions
- For critical tasks
- Measure cycle times (may need mean avg)
- Divide task exposure time by avg cycle time = cycle repetitions
112
What direct manual tool is used to measure joint angles in ergonomics?
A goniometer.
113
How are joint angles measured observationally?
A video or picture is used and the angle is measured with a protractor.
114
Discuss direct methods of measuring dripping and holding forces.
1, Force Transducers
- placed between hand and object or built into object
- relatively high cost
- can be difficult to calibrate
2, Hand Grip Dynanometer
- User estimates force (repetition may be required)
- Relatively cheap
- Can also measure MVC
115
Discuss direct methods of measuring push/pull forces.
1, Push/Pull Force Gauge
- Connected to actual load
- Measure both initial force and sustained force
116
Discuss the use of EMGs in ergonomics.
EMG = Electromyograph
- Can be used on many muscles, such as neck muscles.
- Requires training to interpret
- Beyond scope of OHS ergonomic assessment
117
How are forces measured observationally? Context, Ergonomics.
A subjective, 0-10 graduated scale is used. (No force to Greatest imaginable force)
A 10cm line is drawn with scale of 0-10. The user or observer can then mark on the scale their subjective opinion on the force used.
118
List three different approaches for quantifying the amount of strain a task imposes upon a person.
1) Biomechanical
2) Physiological
3) Psychophysical
119
Compare and Contrast three approaches to quantify the strain of a task on a person.
1) Biomechanical
- Use of models/formula to determine actual force on a specific point
- Useful for quantifying a one-time high force, but does not account for repetition
2) Physiological
- Use of physiologic measurements to assess bodies metabolism and effort.
- Can be hard to accurately measure outside of research setting
- Susceptible to interference from other factors (stress, excitement)
- Useful for measuring stress from repetitive/continuous activity
3) Psychophysical
- Measurements of physiological responses to psychological stimuli
- Can be used to obtain measurements in a short period that would otherwise take a long time
- Can gather data that would otherwise be difficult to measure
120
How are psychophysical measurements taken? Context, ergonomics.
- Subjects are exposed to a task (or that have experience of a task) are asked specific questions about the task.
- Physiologic responses are measured (such as HR) to determine the subjects psychological response to the questions.
- Subjects responses often become less accurate (overconfident) with higher weights and longer durations.
This method was used for:
- The Snook Tables
- The Borg Rating of Perceived Exertion
121
What is RULA?
(Context ergonomics)
Rapid Upper Limb Assessment
Scoring system based upon limb/neck/trunk postures.
- Snapshot in time
- Does not consider duration
- Minimally recognizes force/repetition
- Separate analysis required for asymmetry
- Easy to overestimate risk if focusing on brief extreme postures
- Can underestimate risk in tasks involving force/repetition/duration
122
Give two examples where RULA would be a good risk assessment tool.
- Worker folding laundry at a fixed standing workstation.
- Worker operating a sewing machine at a fixed seated workstation.
123
What is JSI?
(Context ergonomics)
The Job Strain Index is a tool that combines biomechanical, physiological, and epidemiological data to assess ergonomic risk using 6 categories:
- Intensity of Exertion
- Duration of Exertion
- Efforts/Minute
- Hand/Wrist Posture
- Speed of Work
- Duration/Day
124
When should JSI be used and what are it's limitations?
(Context ergonomics)
The Job Strain Index is best used on hand-intensive, repetitive tasks. It is good at predicting risks of epicondylitis and carpal tunnel syndrome.
Eg: Workers tying wire around rebar for reinforced concrete.
Limitations:
- Does not consider vibration, contact stress, temperature, organizational design
- 3 of 6 variables are subjective measurements
- Frequency is limited to max of 20/min
- Does not consider multi-task jobs
125
What is the ART tool?
(context ergonomic risk assessment)
Assessment of Repetitive Tasks
- Numeric and traffic light scoring
- Assesses upper limb MSD risk factors
- Not appropriate for computer workstations
- Focused on repetitive tasks with duration >1hr.
Example: assembly line jobs
126
What is the ACGIH?
The American Conference of Governmental Industrial Hygienists
127
What is the ACGIH HAL-TLV?
(context ergonomics)
American Conference of Governmental Industrial Hygienists
Hand Activity Level
Threshold Limit Value
- Factors amount of hand activity with peak force
- Gives an action level threshold
- Gives a threshold limit
128
What is REBA?
(context ergonomics assessment)
Rapid Entire Body Assessment
Whole-body version of RULA
Scoring system based upon body postures.
- Snapshot in time
- Does not consider duration
- Minimally recognizes force/repetition
- Separate analysis required for asymmetry
- Easy to overestimate risk if focusing on brief extreme postures
- Can underestimate risk in tasks involving force/repetition/duration
129
What is MAC?
(context ergonomics assessment)
Manual Handling Assessment Charts
-Different charts for:
--- Lifting
---Carrying
---Team-Handling
V-MAC = a variant for operations with variable load weights.
130
What are considerations for when MAC should be used as an ergonomics assessment tool?
Manual Handling Assessment Charts...
-Good for high-risk lifting/carrying/team lifting tasks
- can't be used for seated operations
- can't be used for sliding operations
- can't be used for handling animate objects (animals/people)
131
What are the Snook Tables?
(context ergonomics)
A series of 10 tables (5 male/5 female) identifying maximum workload for
- lifting
- lowering
- carrying
- pulling
- pushing
The Snook tables have been adapted for use by:
- Liberty Mutual
The Liberty Mutual MMH Tables
- WorkSafeBC
Push/Pull/Cary Calculator
132
What are considerations for use of the Snook tables?
(context ergonomics)
- Assumes two-handed task
- Does not account for awkward postures
- Does not account for duration
- Assumes proper handles
133
What is RAPP?
(context ergonomic assessment tool)
Risk Assessment of Pulling and Pushing
Charts to assess risk of whole body activities to pull/push objects with/without wheels.
134
What is NIOSH?
National Institute for Occupational Safety and Health.
135
What is the Revised NIOSH Lifting Equation?
The NIOSH Lifting Equation was published in the 80's.
The revised version was published in the 90's.
The equation provides a single weight limit to prevent back pain for 100% males and 75% females.
It should only be used for relatively simple, two-handed, stable lifts.
136
How is the repetition rate of a critical task determined?
1) Task Description
- task list
- subtask list
- activity list
- determine which tasks/subtasks/activities are critical
2) Task Exposure Time
- Job exposure time (work hours minus breaks)
- Task exposure time (time on specific task)
3) Task Exposure Percentage
- Convert task exposure times into percentages
4) Cycle Time
- Time duration of one cycle
5) Repetition Rate
- Divide task exposure time by cycle time
6) Repetitious Movements
- Multiply the number of repetitious movements in one cycle by the repetition rate
137
Describe the force estimation technique for grip strength.
Use a hand-grip dynamometer.
Workers estimate force when using hand-grip dynamometer.
Usually requires repeated measurements and averaging (typically 5 repetitions) to gain consistent estimate.
138
What tool is used to measure joint angles directly? What tool is used to measure joint angles from a picture?
Direct: Goniometer
Picture: Protractor
139
What type of activity is best assessed using a biomechanical approach when conducting ergonomic risk assessments?
Infrequent exertions with heavy loads.
140
What type of activity is best assessed using a physiological approach when conducting ergonomic risk assessments?
High frequency exertions with heavy loads.
141
What type of activity is best assessed using a psychophysical approach when conducting ergonomic risk assessments?
Activities of short duration, low force, and few repetitions.
Subjects are extrapolating own effort from a short period to a full working day.
142
What is RULA and what is it useful for?
(context ergonomics)
Rapid Upper Limb Assessment
- Assess static postures with lower concern for force/repetition
1) select a high risk posture from task description.
2) Record posture (picture) and store elements on worksheet.
3) Use final score for overall action level.
4) Use individual posture scores to identify which aspects of posture contribute most to risk.
143
What are the similarities and differences between:
- ACGIH HAL-TLV
- JSI (Job Strain Index)
Similarities
- Assess risk of MSD to upper limb
- Apply to monotask jobs
- Both give two limit values
- Do not incorporate all risk factors
Differences
- ACGIH HAL-TLV uses two parameters
(hand activity level, normalized peak force)
- JSI uses six parameters
(intensity, exertion duration, effort/minute, hand/wrist posture, speed, task duration)
144
Give 5 examples of tasks where the revised NIOSH Lifting Equation should not be applied.
- Pushing/pulling/carrying
- One-handed lifts
- Unbalanced and animated loads
- Lifting in hot environments
- Lifting when seated or kneeling
145
What risk assessment tool can be used to assess team lifting tasks in an ergonomic assessment?
MAC
Manual Handling Assessment Charts.
146
When performing an ergonomics assessment, can the Snook tables or Liberty Mutual MMH tables be used to assess one-handed tasks?
No
147
When performing an ergonomics assessment, can RULA be used to assess one-handed tasks?
Yes.
Rapid Upper Limb Assessment.
148
When performing an ergonomics assessment, can ART be used to assess one-handed tasks?
Yes.
Assessment of Repetitive Tasks of the upper limbs.
149
Into what 5 categories can engineering risk control principles for ergonomics be organized?
- Force
- Awkward posture
- Static contractions
- Mechanical/contact stresses
- Physical environment (thermal, vibration, flooring)
150
What are rules of thumb for workstation height when a task requires precision, and when a task requires force?
(context ergonomics)
Precision tasks - 2-4 inches above elbow height
Forceful tasks - 4-5 inches below elbow height
151
List 9 general ways that engineering controls can reduce the risk of a task that requires force.
- FORCE ASSISTANCE DEVICES
- POWER TOOLS
- WORKSTATION HEIGHT
- DISTANCE TO A LOAD
- WEIGHT OF AN OBJECT
- CARRYING DISTANCES
- HANDHOLDS
- HEADROOM
- HANDLING ACTIVITY TYPE
Force assistance devices provide all or part of the force for a task (pallet jack, hoist)
Power tools (and ratchet wrenches/systems) reduce repetition and improve anatomical positions
Proper workstation heights improve worker posture when conducting forceful activities
Enabling workers to get close to a load usually reduces risk from leverage.
Splitting loads into smaller loads, or reducing the load itself reduces the risk
Split carrying distances, using transportation devices, or rearranging workstations can reduce carrying risks
Good handholds can improve posture for tasks
ensuring that workers have space to move and position themselves properly can reduce risk
Lowering activities are usually lower risk than lifting, and pushing is lower risk than pulling. Changing the type of activity can sometimes reduce risk
152
List 7 general ways that engineering controls can reduce the risk of a task that involves awkward postures.
- WORK LEVEL/HEIGHT
- POSITION OF WORK IN RELATION TO WORKER
- REDUCE TWISTING
- ADJUSTABILITY
- ARRANGEMENT OF WORKSTATION
- SEATING
- HANDLING TOOLS
Position materials between knuckle and shoulder height. Use devices to bring materials to appropriate height. Keep very heavy materials at knuckle height.
Keep work in front of worker to minimize reaching to sides.
Arrange work to minimize twisting. This may require materials be moved further to force workers to move their feet instead of twisting.
Design workstations to be adjustable to account for variability in worker sizes.
Arrange the workstation so that tools and equipment are readily available in positions that are appropriate. (importance, weight, sequence of use)
Provide well-designed, adjustable seating.
Handling tools (jigs, clamps) can often reduce static contractions and permit more neutral postures. Replaces need to hold objects in place.
153
How can engineering controls be implemented to reduce the risk of a task that involves static contractions?
Design for different working positions (sit/stand desks).
Use tools that can hold/balance objects (jigs/clamps/balances)
154
How can engineering controls be implemented to reduce the risk of a task that involves mechanical/contact stresses?
Round off sharp edges of surfaces which could contact the worker (edges of a workdesk).
Add padding to hard surfaces that may contact a worker.
155
How can engineering controls be implemented to reduce the risk of a task when there are risk factors from the physical environment (thermal, vibration, flooring)?
(context ergonomics)
Separate workers from heat/cold using insulation and other barriers
Insulate hot/cold equipment that may be handled.
Provide air conditioning or heating in hot or cold environments.
156
List 6 ways administrative controls can be implemented to reduce the risk of a task that involves repetition?
- re-sequence jobs to reduce repetition
- reduce task frequency
- provide job enlargement
- provide job rotation
- allow self-pacing of work
- provide rest breaks
Re-sequencing Jobs
(change sequence to break up static contractions, use both hands, or use more/alternate muscle groups)
Job enlargement
(have the worker do more, varied tasks instead of one highly repetitive task)
157
Discuss four common types of PPE used as a hazard control in ergonomics.
Knee Pads
- To reduce mechanical/contact stresses
Gloves
- Properly sized
- High/low friction as appropriate
- Anti-vibration (exists, but often for very specific circumstances)
Wrist Braces
- Commonly used as a treatment, less for PPE
- Often requires rearrangement of workstation to avoid secondary postural problems
Back Belts
- No strong evidence for/against back belts
158
Discuss employee placement as a control method for ergonomic hazards/risks.
For most situations, there are no valid methods to predict whether an applicant will be prone to MSDs. One-time tests of strength do not account for the numerous factors in MSDs.
Exceptions for work, such as firefighting, where there is need for a significant physical capacity may be an exception. Though this may simply test the ability to perform the work not the chances of developing MSDs.
159
Discuss medical management as a control for MSDs.
(context ergonomics)
Medical management to identify and treat MSDs earlier is a type of administrative control.
- Health surveillance (surveys, physical exams)
- Early reporting of symptoms (system & encouragement)
- Prompt review of medical records (provided by health care professionals)
- Walk-throughs by medical staff (basic understanding of job tasks and demands)
160
Name three points that must be considered for job rotation programs to be successful.
1, The jobs should be different in the type of hazard exposure (mix a job with risk of back strain with one where there is no risk of back strain).
2, Training is necessary to ensure workers are able to do both jobs.
3, Union cooperation may be required to address seniority rights.
161
How does the type of work that is being performed affect the appropriate height of a work surface?
Context - ergonomics
The work surface height should be different for precision tasks vs forceful tasks.
Precision tasks - 2-4 inches above elbow
Forceful tasks - 4-5 inches below elbow
162
List 6 considerations for the selection of hand tools that will reduce the change of MSDs.
(context ergonomics)
- Handle diameter
- Handle length
- Grip-type
- Handle/grip cushioning
- designed for neutral posture of upper limb
- designed for use with worker's dominant hand (or either hand)
163
What types of PPE have not been demonstrated to reduce the incidence of injuries?
- Back braces
- Wrist braces (for prevention)
Anti-vibration gloves often fail to protect workers from harmful vibrations.
164
Which four critical elements should be part of a medical management program?
(context ergonomics)
Passive health surveillance
Early reporting systems
Prompt medical record reviews
Plank walk-throughs by medical staff
165
Ergonomics assessment.
Using the user-task-environment model, discuss USER factors that should be considered in the office environment.
Anthropometry
Aging processes
Visual acuity
- Colour blindness?
- Bifocal glasses (lower reading surfaces)
- Character size on screen
- Near/far sighted
166
Ergonomics assessment.
Using the user-task-environment model, discuss TASK factors that should be considered in the office environment.
Prolonged work
- Visual fatigue/eye strain
Static contractions
- Lower back
- Neck & shoulder
Awkward postures
- workstation height
- VDT or document position
- mouse position
- seating
- tendinopathies of the upper limbs
Force
- Less common
- Keyboard, mouse, other equipment
Mechanical/Contact Stresses
- Table edge
- Seat edge
Repetition
- Finger movement repetitions
167
List 4 symptoms of eye strain.
- Blurred vision
- Eye irritation
- Dry burning eyes
- Headaches
168
Discuss the pathophysiology of eye strain related to Visual Display Terminals (VDTs).
There is a known relationship between concentrated work at VDTs and eye strain.
This type of eye strain is not normally associated with permanent disease.
It is caused by lactic acid buildup in:
- Oculomotor muscles (globe movement)
- Ciliary muscles (lens shape/focussing)
- Iris muscles (sphincter/shutter)
169
Identify 3 major muscles of the shoulder/neck that are commonly affected by static contractions in the office work environment.
- Trapezius
(upper back/neck, elevates shoulder)
- Sternoclaidomastoid
(neck, rotates head)
- Deltoid
(shoulder, elevates arm)
170
Discuss the 90-90-90 rule for ergonomics in the office environment.
The 90-90-90 rule in the office is a rule that there should be three angles of 90°. Hips, knees, elbows.
This is somewhat outdated, because the act of sitting rotates the pelvis, resulting in a flattening of the lumbar spine. An angle greater than 90° at the hips will help reduce this awkward posture.
Tilting the seat pan down can help increase the hip angle.
171
Office Ergonomics.
What should be considered when performing an ergonomics assessment on a seated office workstation regarding FORCE.
When seated, more pressure is placed on the front of the lumbar intervertebral discs than when standing.
When seated upright, 2/3 of body weight is distributed to the seat through the ischial tuberosities ("sit bones").
Force may be a factor when operating stiff keyboards or pounding keys/gipping mice when frustrated.
172
Office Ergonomics
List common sources of mechanical/contact stresses for a seated office worker.
- Wrist/forearm against edge of desk (tendons)
- Back of legs against chair seat pan
173
Office Ergonomics
Discuss repetition as an ergonomic risk factor for a seated office worker.
Finger movement repetitions with use of computer or smart phone. Can result in hand-wrist disorders.
Force, posture, and repetition combine to form risk of an activity.
174
Ergonomics assessment.
Using the user-task-environment model, discuss ENVIRONMENTAL factors that should be considered in the office environment.
- Visual
(lighting, glare)
- Thermal
(temperature, humidity)
- Chemical/Biological
(new carpet emissions, stagnant water in air conditioner, mold)
- Air Quality
- Noise
- Organizational Environment
- Psychological Environment
175
How bright should typical office spaces be?
200-500lux
176
What is a good resource for lighting ergonomics?
The IESNA Lighting Handbook
177
Office Ergonomics.
Discuss lighting as an environmental factor in the office environment.
Direct and indirect glare can increase the risk of eye strain.
Brighter light levels result in increased performance in offices without VDTs.
Lower light brightness is appropriate for workers that do a lot of document composition at VDTs.
More light is usually needed:
- when speed/accuracy is critical for the task
- for users over 50yrs
- when the environment is dark (no windows, dark walls)
Overall lighting in most offices should be between 200 and 500 lux.
Some workers are sensitive to flicker of fluorescent lighting.
Most offices should have a "colour temperature" somewhere between warm and cool.
- Chromaticity <3000k = "warm light" with more red tones
- Chromaticity >4000k = "cool light" with more blue tones
178
Office Ergonomics.
Discuss the thermal environment as a factor in the office environment.
Temperature affects comfort.
Humidity affects thermal comfort.
Humidity below 20% dries the skin, eyes, and mucus membranes. Increases static electricity.
Humidity over 70% can cause condensation on surfaces/in equipment.
Drafts, especially at head or legs/feet, can impact thermal comfort.
179
How is office work changing, and how does this change impact the worker from an ergonomics perspective?
- Laptops, tablets, smartphones
- Working from home, car, cafe, anywhere
- Less paper, more VDT changing lighting needs (less bright light)
180
List three types of office workstation surface arrangement and the type of work each is suited for.
- One-surface workstation
for a job with a singular task
- Two-Surface L-Shape Workstation
for a job with two distinct, different tasks done at different times
- Corner Office Workstation
for a job with multiple tasks that require multitasking
181
At what height should a computer monitor usually be positioned?
(office ergonomics)
- The top of the monitor should be horizontal to the level of the eyes.
- The first line of text should be 15 down from the eyes
- Bifocal wearers may require the monitor to be 15 lower
182
List three engineering control measures for improving visual environment.
(context ergonomics)
- Increase task lighting to raise illumination level
- Decrease glare
- Exploit natural lighting
- Change lighting to reduce flicker (example, change fluorescent to incandescent)
183
Describe 4 ways to reduce glare in an office.
(office ergonomics)
- VDT positioning
screens perpendicular to window to prevent worker being directed towards sun and sunlight onto screen
- Use of screen hoods or antiglare filters
- Use of bafflers, louvers, and diffusers
- Use of indirect light (reflected off ceiling or wall)
184
What is illumination?
The amount of light that falls upon an surface.
185
What is luminance?
The amount of light reflected from a surface.
186
What is "contrast ratio"?
A specific type of brightness ratio.
The ratio of luminance of a surface vs the immediate background surface.
187
What device can be used for basic light measurements?
A light meter (aka photometer or luxmeter)
188
What is the IESNA and what do they publish that is helpful for most ergonomists?
Illumination Engineering Society of North America.
Recommendations for room light levels.
189
Give three examples of administrative controls that can be used to reduce the risk if visual environment hazards.
- Cleaning schedules for lamps and screens
- Replace lamps before they wear out (output decreases as lamps age, before they burn out)
- Promote regular eye exercises.
(look 20m away for 20s every 20 minutes)
190
What hand-held tools can an ergonomist use to measure auditory hazards?
A sound-meter or noise dosimeter.
191
What is relative humidity (RH)?
The amount of moisture in the air as a percentage of it's maximum capacity at it's current temperature.
192
What are the four common types of temperature measuring equipment?
What are the basic differences?
- Dry Bulb Thermometer
- Wet-Bulb Thermometer
- Globe Thermometer
- Anemometer
- Dry Bulb Thermometer
Standard thermometer. Measures air temperature aka dry bulb temperature (Tdb)
- Wet Bulb Thermometer
Measures the temperature, factoring in the RH (relative humidity).
(unless RH=100, Twb is lower than the Tdb)
- Globe Thermometer
Measures radiant energy
- Anemometer
Measures air velocity
193
What are the two main categories of vibration that workers may be exposed to?
Whole body vibration
Segmental (aka hand-arm) vibration
194
What tool do ergonomists usually use to measure vibration?
An accelerometer.
195
What are the 8 factors that influence visual performance?
(ergonomics)
- Size (includes distance)
- Contrast
- Time (the duration something can be viewed)
- Illumination
- Glare
- Flicker
- Colour
- Shadow
196
List 3 engineering, and 3 administrative controls for lighting hazards.
(ergonomics)
- Increase illumination
- Reduce glare
- Minimize adaptation (use intermediate brightness areas to transition between areas of high/low light)
- Clean lights/fixtures regularly
- Replace lamps regularly, before they are worn out
- Promote regular eye exercises
197
What are two main types of hearing loss?
- Sensorinueral
There is an impairment of the sensory apparatus or auditory nerves. This can be caused by noise exposure.
- Conductive
There is a mechanical obstruction of the ear canal or eustachian tube.
198
In general, how can engineering controls be used to reduce the risks of noise?
- Control at the source
(Install dampers, maintain machines, alter speed)
- Control along the path
(sound barriers, partitions)
(controlling at the worker is PPE)
199
What are the two main types of hearing protection device?
Ear muffs,
Ear plugs
200
List 4 engineering controls to reduce the risks of a hot environment.
- Increase distance between worker and heat sources
- Install shielding between heat source and workers
- Use fans to increase air velocity
- Install air conditioners
201
List 2 administrative controls to reduce the risks of cold environments
- Rest breaks in rewarming facilities
- Warm beverages
202
What is resonance frequency?
The frequency at which an object is displaced more than that of the original vibration. Different objects (and body tissues) have different resonance vibrations.
203
List two engineering and three administrative controls to reduce the risks of whole body vibration on drivers.
- Control source (maintain roads and equipment to reduce vibrations)
- Control between source and workers (Install dampers between engine and cabin)
- Use a preventive maintenance program
- Reduce driving speeds
- Job rotation
204
What are the 5 basic senses that people use to sense information?
Vision (usually dominant)
Hearing
Smell
Touch
Taste
205
What are the three broadest types of memory?
Sensory Storage
Working Memory
Long-Term Memory
206
How many 'chucks' of information can the working memory of the average person hold at once?
Previously throught to be around 7, now around 4 or 5.
207
What are 5 features of a memorable coding system to present information?
- Detectible (the code/message must be detectable to all users, i.e. bright enough)
- Discriminable (users must be able to distinguish the code/message from the surroundings)
- Meaningful (the users must understand the code)
- Standardized (codes should be standardized to avoid confusion and make it easier to remember)
- Multidimensional (include redundancy in code, such as the colour and position of green/red on traffic lights)
208
Discuss some important aspects of Long Term Memory that should be kept in mind by ergonomists.
Long term memory can store large amounts of information, but retrieval can be slow.
Important/relevant information should remain on display so that rapid long-term memory recall is not necessary.
To help with long term memory recall information should be compatible with the user population in 3 ways:
- Conceptual compatibility
(information uses ideas that the user already knows, such as known abbreviations or symbols)
- Movement compatibility
(the way we expect physical things to be. screws clockwise, buttons on a jacket, driving on correct wide of roads)
- Spatial compatibility
(arranging things by association, such as control switches adjacent to their readouts)
209
What are the four strategies that people can adopt to help when there is too much information at once?
-Selective Attention
(watching for specific key features)
- Focused Attention
(focusing on one source of information and blocking out the rest)
- Divided Attention
(splitting focus between equally important sources. Best achieved when sources are close together and in a logical order)
- Sustained Attention
(monitoring a field of view for an occurrence/event. Performance usually drops dramatically after 30 minutes)
210
Discuss feedback as it relates to cognitive ergonomics and information transmission.
Feedback is important for users to learn from their actions.
- sooner the better
(click of a button)
(light on a button)
(verbal confirmation from colleague)
211
What are 6 basic considerations that must be followed when designing displays/controls?
- Is the display/control necessary?
- Can the display/control be easily identified?
- Can the display/control be easily understood?
- Does the display/control cause confusion?
- Is the sequence of use logical?
- Does the display adhere to the cultural expectations of users?
212
Discuss visual vs auditory displays as a means to providing users with information.
Visual displays are useful for:
- User in specific position
- Complex information
- Information needs to be referred to later
- Noisy areas
Auditory displays are useful for:
- User is moving around
- Immediate action is required
- Short, simple messages
- Information is only referred to once
213
Give 4 rules of thumb for the use of colours in visual diplays.
- Use a maximum of 4 colours per display
- Avoid red & blue adjacent to each other (very different wavelengths, eyestrain)
- Only use blue for backgrounds, not text/lines
- Avoid red and green for small letters or symbols
214
Discuss the placement of visual displays for giving users information.
(context ergonomics)
- Display should be within workers visual field
- Use a link analysis
--- Determine which displays are more important or used most frequently
--- Determine logical sequence for displays
215
What are the characteristics of a good coding system?
(cognitive ergonomics)
A good coding system should be:
- detectable
- discriminable
- meaningful
- standardized
- multidimensional
216
List 3 methods to improve working memory
(cognitive ergonomics)
- Paying attention and rehearsing information
- Encoding information
- Chunking information
217
List 3 methods to improve long-term memory
(cognitive ergonomics)
- Keep relevant information on display
- Give information that is conceptually compatible (matches user expectations)
- Give information that is movement compatible (matches user expectations)
- Arrange information that is specially compatible (associations and order are readily apparent)
218
List 4 strategies to direct attention when there is a lot of information for a user to process.
(cognitive ergonomics)
-Selective Attention (watching for specific features)
- Focused Attention (paying attention to one singular info source)
- Divided Attention (splitting focus between info sources)
- Sustained Attention (monitoring a field an occurrence/event)
219
Give 5 situations where an auditory display a better choice than a visual display?
- User needs to respond quickly
- User moves around rather than working in one place
- Information is short/simple
- Information will only be referred to once
- Users visual system of the person is overburdened or lighting is poor
220
How is link analysis used by ergonomists to help in the design of controls and information displays?
Link analysis can help with identifying importance, frequency, and sequence of use for controls and displays.
221
What are four design guidelines that should be considered when arranging controls?
- Functional reach
- Grouping by function
- Sequence of use
- Adequate spacing
222
Identify and list 7 common reasons why ergonomics programs might fail in an organization?
- Lack of management support
- Lack of behavioural modification
- Resistance to change
- Trying to implement too much too quickly
- A lack of belief/buy in in the program
- A directive approach without employee involvement
- Poor implementation strategies & employee training
223
5-Step Ergonomics Program.
List the 5 main steps, of the 5-step model for introducing a new ergonomics program.
1, Gain organizational commitment and involvement.
2, Plan for intervention.
3, Identify and assess risk.
4, Implement controls.
5, Monitor and evaluate the program.
224
5-Step Ergonomics Program.
Discuss how to gain organizational commitment and involvement for an ergonomics program.
- Support needed from decision-makers (owners, senior managers, union, workers in key positions)
- Gather Data
(injury, compensation, absenteeism, employee turnover, quality control, material waste)
- Cost-Benefit
(one-time cost for ongoing benefits, increased productivity, reduced error)
225
5-Step Ergonomics Program.
Discuss how to plan for intervention when implementing an ergonomics program.
- Strategic Plan (goals, barriers, measurements)
- Tactical Plan (How to achieve goals, timeframes, logistics)
- Ergonomics Committees
} Often needed
} mixed membership
} Develops, implements, and monitors program
- Ergonomics Training
} Ergonomics committee members may require training
} Often helpful to provide training to workers too
226
5-Step Ergonomics Program.
Discuss Identifying and Assessing Risk when introducing a new ergonomics program.
- Use focus groups, documentation reviews, and walk-through checklists
- Determine areas of greatest immediate need (incident rates/severity, probability of effective change, risk factor number/severity)
- When possible start with a project that will give quick, measurable results. (garner support for future projects)
227
What are 4 common reasons why ergonomics programs fail?
- Lack of management support
- Trying to implement too much too quickly
- Directing without employee involvement
- Poor training
228
Describe the three different types of ergonomics programs.
1, Ensuring the organization meets legal obligations.
(minimum required effort)
2, Use of a contracted ergonomist to give recommendations.
(typically narrow focus and not sustained)
3, Cooperative, active effort between employer and workers in ergonomics initiatives.
(most effective)
229
How might you go about justifying an ergonomics program?
Use data to create a business case:
- first aid reports
- medical & compensation costs
- incident & near-miss statistics
- Quality control
- Absenteeism
- Employee turnover
230
List the five stages of developing a successful ergonomics program.
1, Management commitment.
2, Plan for intervention.
3, Identify and assess risk.
4, Implement controls.
5, Monitor and evaluate.
