Ergonomics: Why do workers get injured? Presented by: Steve Bilan Ergonomic Specialist
What do you know about Ergonomics?
• Ergonomics is the study of designing equipment and devices that fit the human body, its movements, and its cognitive abilities.
What do you know about Ergonomics?
• Equipment: Anything that requires any sort of human input to make it work
• Movements: Any body movement required for the task
• Cognitive Abilities: Intelligence and behavior, especially focusing on how information is
represented, processed, and transformed (in faculties such as perception, language, memory, reasoning, and emotion) within nervous systems
Cognitive Ability
Factors that will impact Cognitive perception: • Sleep Deprivation • Noise • Medications • Work Scheduling • Stress • Research is also finding diseases such as Hypertension
have a major role in cognitive ability. • What does this means in regards to ergonomics?
Riddle
• What goes up but does not come down?
Answer
•AGE
How does this contribute to a Musculoskeletal injury/Disorder?
Safe Workload • IF WE CAN CONTROL FATIGUE, WE CAN
TAKE AWAY MSD’S • Under regular good working conditions with
sufficient rest breaks injury is not as likely occur
• Miniature rest breaks are essential throughout the day to prevent injury
Safe Workload
Time
Forc
e
Workload Tissue Tolerance
Rest Periods
Workday
520
520
520
520
520
620
719
818
916
1013
911
810
711
613
514
615
716
815
914
1012
911
810
711
613
514
615
716
815
914
1012
911
810
711
613
514
615
716
815
914
1012
Workload
Tissue Tolerance
Time
Force
Workday
Actue Injury
520
520
520
520
520
3020
56
56
56
56
56
57
57
57
58
58
59
59
109
56
56
56
Workload
Tissue Tolerance
Time
Force
Acute Injury
Chronic Injury
518
518
518
518
518
1017
1016
1015
1013
1011
512
513
514
516
517
1017
1016
1014
1012
1011
512
513
514
515
516
1016
1015
1013
1012
1010.5
511
512
513
514
515
1014
1013
1011
1010
105
56
56
56
57
58
Workload
Tissue Tolerance
Time
Force
Chronic Injury
Stats
WorkdaySafe WorkloadToo Many HoursAcute InjuryChronic Injury
520520520520518
520520520520518
520520520520518
520520520520518
520520520520518
6201019101930201017
71910171017561016
81810151015561015
91610131013561013
101310111011561011
91151251256512
81051451457513
71151651657514
61351851857516
51452052058517
61510191019581017
71610171017591016
81510151015591014
914101310131091012
101210111011561011
91151251256512
81051451456513
711516516514
613518518515
514520520516
615101910191016
716101710171015
815101510151013
914101310131012
1012101110111010.5
911512109511
810514107512
711516105513
613518514
514520515
61510191014
71610171013
81510151011
91410131010
10121011105
56
56
56
57
58
Safe Workload
520
520
520
520
520
1019
1017
1015
1013
1011
512
514
516
518
520
1019
1017
1015
1013
1011
512
514
516
518
520
1019
1017
1015
1013
1011
512
514
516
518
520
1019
1017
1015
1013
1011
Workload
Tissue Tolerance
Time
Force
Too many hours
520
520
520
520
520
1019
1017
1015
1013
1011
512
514
516
518
520
1019
1017
1015
1013
1011
512
514
516
518
520
1019
1017
1015
1013
1011
109
107
105
Workload
Tissue Tolerance
Time
Force
Working too many hours
Forc
e
Time
Workload Tissue Tolerance
Chronic Injury
Workday
520
520
520
520
520
620
719
818
916
1013
911
810
711
613
514
615
716
815
914
1012
911
810
711
613
514
615
716
815
914
1012
911
810
711
613
514
615
716
815
914
1012
Workload
Tissue Tolerance
Time
Force
Workday
Actue Injury
520
520
520
520
520
3020
56
56
56
56
56
57
57
57
58
58
59
59
109
56
56
56
Workload
Tissue Tolerance
Time
Force
Acute Injury
Chronic Injury
518
518
518
518
518
1017
1016
1015
1013
1011
512
513
514
516
517
1017
1016
1014
1012
1011
512
513
514
515
516
1016
1015
1013
1012
1010.5
511
512
513
514
515
1014
1013
1011
1010
105
56
56
56
57
58
Workload
Tissue Tolerance
Time
Force
Stats
WorkdaySafe WorkloadToo Many HoursAcute InjuryChronic Injury
520520520520518
520520520520518
520520520520518
520520520520518
520520520520518
6201019101930201017
71910171017561016
81810151015561015
91610131013561013
101310111011561011
91151251256512
81051451457513
71151651657514
61351851857516
51452052058517
61510191019581017
71610171017591016
81510151015591014
914101310131091012
101210111011561011
91151251256512
81051451456513
711516516514
613518518515
514520520516
615101910191016
716101710171015
815101510151013
914101310131012
1012101110111010.5
911512109511
810514107512
711516105513
613518514
514520515
61510191014
71610171013
81510151011
91410131010
10121011105
56
56
56
57
58
Safe Workload
520
520
520
520
520
1019
1017
1015
1013
1011
512
514
516
518
520
1019
1017
1015
1013
1011
512
514
516
518
520
1019
1017
1015
1013
1011
512
514
516
518
520
1019
1017
1015
1013
1011
Workload
Tissue Tolerance
Time
Force
Safe Workload
Too many hours
520
520
520
520
520
1019
1017
1015
1013
1011
512
514
516
518
520
1019
1017
1015
1013
1011
512
514
516
518
520
1019
1017
1015
1013
1011
109
107
105
Workload
Tissue Tolerance
Time
Force
Working too many hours
Rest and Recovery
• During the rest phase, physiologically your body is seizing the opportunity to repair itself to become stronger in preparation for the next stresses placed upon it
• Not surprisingly, as you get older, the more your body relies on rest and recovery time.
Rest and Recovery
• The recovery rate closely relates to how fast the body can grow new cells to repair itself.
• Studies show that injured athletes 45 and older recover between 15 to 18 percent more slowly than a similarly injured 30-year-old.
Rest and Recovery of individuals later in life
Fool Proof Prevention • To ensure that your design will not cause injury
the most important factor of your design is to ensure that REST and RECOVERY periods are sufficient to recover from the demands of the tasks workers perform
• The body is self repairing and can repair itself throughout the day
• This does not mean coffee breaks. This is the application of work at the right times for employee
TRUE or FALSE
• If all your muscles could pull in one direction you could create a force of 1000 lbs!
FALSE • If all your muscles could pull in one direction
you could create a force of 25 tons!
How to identify risk factors for MSI/MSDs (poor ergonomics)
Ergonomics 5 W’s and a H (A Task analysis)
• Who • What • Where • When • Why • How
Who
• Workers • Age (as mentioned earlier) • Height • Capabilities • Previous Injuries/General Health • Anthropometrics • Training History • Job Experience
What
• Tasks are being performed, workstation, environment, work structure
• Necessary and unnecessary movements, motions, lifts, etc
(What) Work System
Employee
Task
Work Structure
Workstation
Environment
Task – What is the job description – What are the essential steps – Physical Demand Description (PDD) – Safety – Skill requirement
Workstation – Equipment and Tools – Machinery – Workstation layout – Measurements such as height, width, depth – Weights of objects
Environment – Light levels – Noise levels – Vibration levels – Temperature – Air Quality
Work Structure
• Production Rate • Training • Supervisor • Management Style • Policies and Procedures • Workload
Where
• Areas that are at the greatest risk • How do you determine where?
Tools that can be used to identify tasks for potential injury
• MSI survey • Risk Analysis Checklist • Injury History • WCB information • Talking with employees • Reviewing OHC committee minutes and first
aid kit logs
MSI Survey MSI SURVEY FORM 1. What department do you work in? ________________ What is your job title? _____________________________ 2. In the last year, have you had any pains, aches, soreness, numbness, tingling, swelling, burning feelings, muscle
weakness, muscle tightness, changes in skin colour or difficulty in grasping or holding objects, that have lasted for more than a week, that you believe are mainly caused by your work? YES NO. If YES, please complete the remainder of this survey. If NO, you do not have to complete the rest of the survey.
3. How long have you worked in your present job? Less than 1 year 1 – 5 years More than 5 years 4. How many hours do you work at your job each week, not including lunch and coffee breaks? __________________ 5. How long are your daily breaks at work?____________________________________________________________ 6. List the 2 most physically demanding (forceful, awkward or repetitive, etc.) tasks that you do at work? _________ ______________________________________________________________________________________________ 7. How often do you perform these tasks?_____________________________________________________________ 8. Please put an X in the boxes in the table below that apply to you.
In the last 2 months I have had symptoms (such as aches, pains, discomfort, or numbness) in my:
In the last 7 days I have had symptoms (such as aches, pains, discomfort, or numbness) in my:
Neck No Yes
Neck No Yes
Shoulders No Yes
in the right shoulder in the left shoulder
Shoulders No Yes
in the right shoulder in the left shoulder
Elbows No Yes
in the right elbow in the left elbow
Elbows No Yes
in the right elbow in the left elbow
Wrist / Hands No Yes
in the right Wrist / Hand in the left Wrist / Hand
Wrist / Hands No Yes
in the right Wrist / Hand in the left Wrist / Hand
Upper Back No Yes
Upper Back No Yes
Lower Back (Small of Back) No Yes
Lower Back (Small of Back) No Yes
One or both hips/thighs/buttocks No Yes
One or both hips/thighs/buttocks No Yes
One or both Knees No Yes
One or both Knees No Yes
One or both Ankles / Feet No Yes
One or both Ankles / Feet No Yes
Risk Analysis Checklist Risk Analysis Checklist
Department:
Position:
Comments: Comments:
Comments:
Comments:
Comments:
Comments:
Comments:
TravellingBreaks extending past normal durationsNo rotation schedule
Risk Level = 0.00
MonotonyInformation handling demandsComplex decision makingDeadline pressures
Othat Factors:Shift work
High skill requirementMental Load:
Multiple tasks done simultaneouslyTactile requirementsTraining time highHigh concentration requirements
VibrationPoor handles / grips (pressure points, sharp edges, etc.)
Hand Tool Use:Heavy hand tools (>10 lb.)Bent wrist postures with tool usage
Lack of handling aids
Controls and Displays:Poor compatabilityNo display lightingFrequent used controls not centrally locatedControls are confusing or not easily identifiedControls are too smallFrequent operation of controls appears rushedControls labeled and marked
Static holding or carryingFrequent stair or ladder climbing
Physical Demands:
Load above 40 lb.Sudden or jerky movementsEndurance requirementsPoor grips
Frequent heavy liftingLifting from overhead or below the waistObstructed pathwayTwisting while lifting
Glare (direct of reflected)Hot surfacesSlippery floor surfaces
Awkward objects to lift (bulky, large)
Humid
High noise levelsPoor task lightingPoor ambient lightingCold temperatures (require PPE)
Environment:
Hot temperaturesFumes and vaporsPoor air circulation
Controls / parts require reachingPoor working heights (bending required to perform)CrowdingComponents beyond normal reachesPoor chairs (not adjustable, no back support, no foot rest)No adjustability in workstation
Awkward Postures (bending, twisting, above shoulder, etc.)Workplace Characteristics:
Static / Sustained muscle workNo sitting while performing the job
Injury History- Injury Log Log of Work-Related Injuries & Illnesses Resulting in Lost Time or Medical Treatment
Department: __________________ Year: _________
Date Body Part Injured
*Type of Injury
*Direct Cause of Injury
**Systemic Cause of Injury
Work Area
Occupation Shift/Time of Day
Steps Taken to Prevent Similar Injuries
Example 1 May 1/11
Back Strain Lifting
No mechanical lifting devices
Bin assembly
Labourer Days/No specific time
Purchased gantry crane. Managers and supervisors must ensure that all safety policies are enforced.
Example 2 June 6/11
Eye
Scratch Metal chip in eye
Eye protection not worn; did not fit.
Bracket making
area.
Welder Evening Shift/
7:00 PM
Purchased various sizes & types of eye protection. Eye protection program established. Supervisors annual pay increments tied to enforcement of health & safety policies and injury statistics for their area of responsibility.
Example 3 Aug 7/11
Wrist Carpal Tunnel
Repetitive Motions
No job rotation Data Entry Data Entry Clerk
Daytime/ Cumulative
Data entry clerks and file clerks rotate jobs every 2 hours.
* For type of injury and cause of injury use only 1 or 2 words whenever possible such as fall, trip, knife cut, lifting, repetition, fracture, hit thumb, pushing, pulling, etc. ** Example: Direct Cause of Injury - Employee didn’t have guard on saw Systemic Cause of Injury – Inadequate training provided to employee or safety policies not being enforced by manager/supervisor. *** Modified work is also called light duty work etc., (All modified/light duty work needs to be purposeful, productive work.)
Committee Minutes
Talking with Employees
Early warning signs of MSIs • Numbness • Pain • Tingling • Swelling and Inflammation • Burning sensations • Weakness • Red skin
When
• Proactive is the best, prevent injuries from happening before they happen
• Immediately after incident
Why
• Reduced risk of PAIN or INJURY • Positive feelings about work • Ability to work at full potential. • Higher quality of life when at work and
when away from work
How How do you know what to look for? 1. Amount of FORCE needed to perform all or
part of job task 2. AWKWARD POSTURE (arm, wrist, neck,
leg, back, etc.) required by the job or job task
3. Amount of REPETITION in the job
EMG
• Electromyography (EMG) is an electro diagnostic medicine technique for evaluating and recording the electrical activity produced by skeletal muscles
FORCE
• Force is not weight. • Force is defined as a push, pull, or lift acting
upon an object. • Force required to do a certain task depends
on several factors. • Force can be measured using a force gauge
dynamometer.
Force
AWKWARD POSTURES • Awkward postures can be defined as any posture
where any joint deviates from its natural neutral position.
• This could be a bent wrist, back, neck, raised shoulders, etc.
• When any joint is in an awkward posture the muscles are stretched and the joint becomes weak and susceptible to injury.
• Ideally joint deviation should be 0, this will minimize the torque about a joint
How
• Examples of Awkward Postures
Examples of Awkward Postures
REPETITION
• Definitions: 1) Cycle time of less than 30secs; where the cycle
time is the time to do one operation (Silverstein et al, 1986). This is a definition from the automotive industry
2) Cycle time less than 1 minute is monotonous (Kivi, 1984)
3) Over 120 cycles/hour (Sjogaard et al, 1987)
Repetition
• We can look at repetition several ways, for example: – Parts/hour – Movements/hour – Pauses in a cycle – Periodization of rest breaks
• Repetitive Motions
Examples of Repetition
Combining Risk Factors
Force and Posture
Height of object being lifted: – 36”
Distance of object from body – 15”
Back compression force – 453.51lbs
Weight of object – 25 lbs
The NIOSH Action limit is 770lbs of back compressive force (at L5/S1)
Force and Posture
Height of object being lifted: – 36”
Distance of object from body – 33”
Back compression force – 1027.33lbs
Weight of object – 25 lbs
The NIOSH Action limit is 770lbs of back compressive force (at L5/S1)
Lifting a relatively light object can cause large compressive forces in the spine.
Height of object being lifted: – 6” Distance of object from body – 17” Back compression force – 860.75 lbs Weight of object – 25 lbs The NIOSH Action limit is 770lbs of back compressive force (at L5/S1) This means that even this task of lifting 25lbs once is potentially unsafe
Force and Posture
To Summarize
• Reducing or eliminating unnecessary movements (Repetition) and/or awkward postures and/or excessive force will greatly reduce musculoskeletal injuries, because it will decrease the workers fatigue.
• When workers are fatigued they are at greater risk to become injured both chronically and Acute.
Questions?
Slide Number 1What do you know about Ergonomics?What do you know about Ergonomics?Cognitive AbilityRiddleAnswer�How does this contribute to a Musculoskeletal injury/Disorder?Safe WorkloadSafe Workload Chronic Injury Rest and RecoveryRest and RecoveryRest and Recovery of individuals later in lifeFool Proof PreventionTRUE or FALSESlide Number 16How to identify risk factors for MSI/MSDs (poor ergonomics)Ergonomics 5 W’s and a H� (A Task analysis)WhoWhat(What) Work SystemTaskWorkstationEnvironmentWork StructureWhere Tools that can be used to identify tasks for potential injuryMSI SurveyRisk Analysis ChecklistInjury History-Injury LogCommittee MinutesTalking with Employees�WhenWhyHowEMGFORCEForceAWKWARD POSTURESHowSlide Number 41Slide Number 42REPETITIONRepetitionSlide Number 45Examples of RepetitionCombining Risk FactorsForce and PostureForce and PostureForce and PostureTo SummarizeQuestions?