Measures of Central Tendency: Mean, Median and Mode
Ergonomics
1. Ergonomics:
A work place realities in Pakistan
Asim Zaheer1, Dr. Rameez Khalid
Department of Industrial & Manufacturing Engineering,
NED University of Engineering & Technology,
Karachi, Pakistan
1
corresponding author: asimzaheer@neduet.edu.pk
2. 2
Topics To be Discussed
I. INTRODUCTION
II. CONTEXT
III. PROBLEM STATEMENT
IV. RESULTS
V. ERGONOMICS AWARENESS PROGRAM
VI. CONCLUSIONS
Ergonomics: A work place realities
in Pakistan - Asim Zaheer
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I. INTRODUCTION
What is Ergonomics?
• Ergonomics, is derived from the Greek word
‘ergon’ which means work and ‘nomos’
means law [1-3]
• The Science of Work or the Study of Work
• Designing the job to fit the worker
• Improve the human well-being
• Optimize overall system’s performance
Ergonomics: A work place realities
in Pakistan - Asim Zaheer
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I. INTRODUCTION(Cont..)
• Focus on worker
• Physical and psychological
capabilities
• Keep an eye on human
limitations
• Harmonious relationship
• Enhancement of productivity
and efficiency [2]
This guy needs more
than a new chair!!!!
5. 5
II. CONTEXT
In Pakistan, knowledge of ergonomics is in its infancy
• Ignorance among employer & employee
Ergonomics include different scientific disciplines: [6, 7]
Physiology Biomechanics Psychology
Anthropometry Industrial hygiene Kinesiology
Physical stresses and musculoskeletal disorders (MSDs)
MSDs are also referred interchangeably as CTDs: [10, 11]
• Repeated trauma, Repetitive Stress Injuries (RSIs) and
• Occupational overexertion syndrome
Ergonomics: A work place realities
in Pakistan - Asim Zaheer
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II. CONTEXT(Cont..)
According to Cohen [8], MSDs result in:
• Delays, Absenteeism, Injuries, Illnesses
Risk factors associated with MSDs are: [11, 12]
• Repetitive motion
• Force-full exertion
• Vibration
• Mechanical compression
• Awkward body postures
• High noise
• Low lighting
• Extreme temperatures
Ergonomics reduce MSDs by more than 50% [9]
Ergonomics: A work place realities
in Pakistan - Asim Zaheer
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II. CONTEXT(Cont..)
MSDs affect [4] Symptoms of MSDs:[11]
• Upper limb • pain
• Neck • numbness
• Back • Tingling
Work place common • stiff joints
• difficulty in moving
MSDs are CTS and
• muscle loss
back injury [10]
• paralysis
Prolong working hours • Disorders
Ergonomics: A work place realities
in Pakistan - Asim Zaheer
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II. CONTEXT(Cont..)
Two law enforcing agencies:
• NIOSH (National Institute of
Occupational Safety and
Health)
• OSHA (Occupational Safety
and Health Administration)
Human body is divided into
three planes: [6,7,13]
• Sagittal plane,
• Coronal plane and
• Transverse plane
Ergonomics: A work place realities
in Pakistan - Asim Zaheer
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II. CONTEXT(Cont..)
Wrist movement classified as:
• Flexion
• Extension
• Radial
• Ulnar
Hand movements are
classified as:[13]
• Abduction
• Adduction
• Supination
• Pronation
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II. CONTEXT(Cont..)
Job analysis tools:
• Strain Index (SI),
• Rapid Upper Limb Assessment (RULA)
• Rapid Entire Body Assessment (REBA)
• Ovako Work Assessment System (OWAS)
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II. CONTEXT(Cont..)
Strain Index (SI):[14]
• Number (score)
• Upper extremity disorders.
• Tool to evaluate the job, not the worker
SI = (Intensity of Exertion Multiplier)
× (Duration of Exertion Multiplier)
× (Efforts per Minute Multiplier)
× (Posture Multiplier)
× (Speed of Work Multiplier)
× (Duration per Day Multiplier)
Ergonomics: A work place realities
in Pakistan - Asim Zaheer
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II. CONTEXT(Cont..)
Rapid Upper Limb Assessment (RULA) [6, 17]
• Number (score)
• Upper limb disorders
Wrist
Forearms
Elbows
Shoulders
Neck
Trunk
Rapid Entire Body Assessment (REBA) [18]
• Number (score)
• Entire body assessment
Ergonomics: A work place realities
in Pakistan - Asim Zaheer
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III. PROBLEM STATEMENT
Manufacturing Industry of two wheelers
OEM (Original Equipment Manufacturer) vendor
for famous companies of auto-bikes in Pakistan
Products include:
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III. PROBLEM STATEMENT(Cont..)
Analysis Tools and Procedures:
• Strain Index (SI)
• Exclusively focused on wrist and hand
• Recorded videos
• Critical analysis of working postures
• Gathered relevant data
• Taken snaps
Ergonomics: A work place realities
in Pakistan - Asim Zaheer
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IV. RESULTS
SI for Posture 1
• Rating Criteria Table
• Multiplier Table[14]
• SI Calculation
S.NO. SI Parameters Rating Multiplier
Ergointelligence™
1 Intensity of effort 2 3
2 Percentage 3 1.5
Other Postures duration
3 Effort per minute 2 1.0
4 Wrist Posture 3 1.5
5 Speed of work 4 1
6 Duration / day 3 0.75
SI = 5.1
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IV. RESULTS (Cont..)
SI FOR POSTURES
Action Mean Incidence
Posture Problems SI Risk Type
Needed Rate [14]
Wrist Flexion
Abduction
Caution 77 injuries per 100
1 Force 5.1 Some Risk
required worker per year
Neck flexion
Hard grip
Wrist Flexion
Abduction
Caution 77 injuries per 100
2 Grip force 6 Some Risk
required worker per year
Neck flexion
Trunk flexion
Wrist extension
Abduction Immediate 77 injuries per 100
3
Force
27 Hazardous
action worker per year
Hard grip
Wrist flexion
Abduction
Immediate 77 injuries per 100
4 Force 20.25 Hazardous
action worker per year
Neck flexion
Trunk flexion
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IV. RESULTS (Cont..)
SI FOR POSTURES
Mean
Action
Posture Problems SI Risk Type Incidence Rate
Needed
[14]
Wrist flexion 2 injuries per
5 Excessive 2.6 Safe situation No action 100 worker per
reaching year
2 injuries per
Extreme bending Caution
6 4.5 Uncertain 100 worker per
Wrist flexion required
year
Wrist extension
77 injuries per
Force Caution
7 6 Some Risk 100 worker per
Hard grip required
year
Neck flexion
Wrist flexion 2 injuries per
Caution
8 Neck flexion 3 Uncertain 100 worker per
required
Trunk flexion year
Wrist
flexion/extension
77 injuries per
Upper arm Caution
9 6 Some Risk 100 worker per
abducted required
year
Force
Neck flexion
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V. ERGONOMICS
AWARENESS PROGRAM
Proposed Ergonomics Awareness program:
• Phase 01: Analysis of work place
• Phase 02: Prevention and control of Hazards
• Phase 03: Personnel training and education
• Phase 04: Medical Management
Ergonomics: A work place realities
in Pakistan - Asim Zaheer
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VI. CONCLUSIONS
Findings
• Realities in Pakistani Industry
• Strain Index (SI)
• Worker is at risk; Awkward postures
• Poor environment; Injury prone jobs
Perspectives
• Awareness program
• RULA
• REBA
Ergonomics: A work place realities
in Pakistan - Asim Zaheer
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Acknowledgment
THANK YOU for your attention
Questions
Contact: asimzaheer@neduet.edu.pk; +92 (0)321 2700850
Editor's Notes
Now a days, Industrial safety has become a huge concern in industries of Pakistan. Ergonomics can be defined simply as the study of work Ergonomics, designing the job to fit the worker, rather than physically forcing the worker’s body to fit the job. Its objective is to improve the human well-being and optimize overall system’s performance. Ergonomics is not a new science, although the term has become more common lately. The phrase was first coined in 1857
The main focus of ergonomics is the ‘worker’, whether the situation is designing of work-place or issues relevant to everyday life. Ergonomics keeps an eye on the physical and psychological capabilities as well as the limitations of humans to evade unsafe, unhealthy or uncomfortable situations at the work place This helps to ensure a harmonious relationship between employer and employee, resulting in the enhancement of productivity and efficiency [2]
knowledge from different scientific disciplines including physiology, biomechanics, psychology, anthropometry, industrial hygiene and kinesiology [6, 7] The art of fitting the task, work station, tools and equipment according to the physical abilities of a worker helps the employer to reduce the physical stress and the work related disorders known as musculoskeletal disorders (MSDs) MSDs include injuries to soft tissues, tendons, ligaments and nervous system. It affects bones, muscles and tissues which form the body joints [10], especially the arm and the back [8]. MSDs are also referred interchangeably as CTDs, repeated trauma, Repetitive Stress Injuries (RSIs) and occupational overexertion syndrome [10, 11].
Mostly, MSDs affect the upper limb (arm, shoulder, elbow, wrist and hand), neck and the back that become worse by prolonged working [4]. The problems caused by MSDs are pain, numbness, tingling, stiff joints, difficulty in moving, muscle loss, paralysis and disorders that include Carpel Tunnel Syndrome (CTS), Tendinitis, Sciatica, Herniated disk and back pain [11]. Two common MSDs in the work place are Carpel Tunnel Syndrome (CTS) and back injury. Repetitive motion and high force are responsible for the CTS [10], which affect the wrist and hand by compressing the median nerve which passes through the carpel tunnel in the wrist [11]
Sagittal plane (divide the body into right and left halves), Coronal plane (divides the body into front and back portion) and Transverse plane (divide the body into upper and lower parts)
Rapid Upper Limb Assessment (RULA) On the work place, problems arise due to awkward postures, force and the nature of task and thus provide a reason for more exposed body parts than only wrist and hand. For this situation RULA may be employed, as it is a job analysis tool used to analyze the body segments such as Wrist, Forearms, Elbows, Shoulders and Neck. Like SI, RULA assessment provides a number (score) which provides the information to the analyst about the disorders only in the upper limb [6, 17]. Rapid Entire Body Assessment (REBA) Job analysis tool used to analyze the entire body. REBA assessment provides a number (score) after measuring respective parameters, provides the information to the analyst about the worker’s whole body condition, risk level and suggests how the action may be taken [18].
This paper presents the conditions of an automobile industry that is involved in manufacturing various parts for two wheelers. Basically, the firm is an OEM (Original Equipment Manufacturer) vender for famous companies of auto-bikes in Pakistan. This industry has three facilities: press part unit, manufacturing/assembling unit and electro plating unit. Most of the products are manufactured in the manufacturing/assembling unit, and at the end, all the products are sent to plating unit for electroplating. There are altogether 200 workers excluding the management staff. For this study we have focused only on the Manufacturing Unit of this industry, where we studied the workers individually, interviewed them, recorded videos and took photos of their working postures. In the manufacturing unit many jobs were found having high severity risk factors, but to our astonishment none of the injuries has ever been reported to top management and only minor accidental records were found. In case, a worker feels discomfort, the worker is suggested to take some days off and if something serious happens, apart from some worker most have no right to claim any compensation because most of the workers are on daily wages and thus don’t have any legal contract with the company.
There are various tools available for job analysis as presented in the previous section; we have selected Strain Index (SI) technique as a first step in job analysis to exclusively focus on wrist and hand postures. Table 4 shows the selected photos of different jobs performed at the manufacturing unit. After a critical analysis of the recorded videos and the gathered data, Strain Indices were calculated and as an example the calculation for posture 1 is presented next.
Moore and Garg [14] have provided the tables for “rating criteria” and “multiplier”, which are used here to evaluate the SI for posture 1. First, the rating criteria (table-I in [14]) are selected for each multiplier along with the value of the corresponding multiplier (table-II in [14]). Table 1 has already provided a description of the six multipliers and the SI calculation using (1) for posture 1 is presented below (similarly the Strain Indices for all nine postures are shown in the table 5): Intensity of effort rating 2, multiplier of 3 Percentage duration of exertion rating 3, multiplier of 1.5 Effort per minute rating 2, multiplier of 1.0 Wrist Posture rating 3, multiplier of 1.5 Speed of work rating 4, multiplier of 1.0 rating 3, multiplier of 0.75 SI = 3 × 1.5 × 1.0 × 1.5 × 1.0 × 0.75 SI= 5.1 (means worker is at some risk and caution is needed to save the worker)
Proposed ergonomics awareness program consists of the following four phases on the lines of OSHA , though the underlying details are extended keeping the Pakistani industrial context in mind: Phase 01: Analysis of work place Phase 02: Prevention and control of Hazards Phase 03: Personnel training and education Phase 04: Medical Management
This paper highlighted the facts related to ergonomics in a manufacturing unit of a Pakistani automobile industry. In this facility workers are working in a poor environment with awkward postures of hand and wrist. The data collected at this facility, through signs and symptom survey forms, reveal that more than 50% problems lie in the upper extremity of a worker’s body. Strain Index (SI) was used to analyze this upper extremity (only hand and wrist). An ergonomics awareness program was proposed to enhance the workers’ knowledge and capability by improved learning about injury-prone jobs and postures involving the use of wrist and hand. In another paper we will provide the extensive analysis on those jobs in which whole body is involved using the postural analysis tools like Rapid Upper limb Assessment (RULA) and Rapid Entire Body Assessment (REBA). This paper proposes an ergonomics awareness program, if employed in its true spirit will surely increase workers’ morale, and will help enhance the communication and cooperation between the management and their employees for higher productivity and profitability.
