Risk Factor Identification

1
Risk Factor Identification
2
Risk Factors

• Repetition
• Force
• Forceful Exertion
• Direct Mechanical Pressure
• Vibration
• Posture
• Awkward Posture
• Static Posture
• Environmental Stressors

3
Repetition
The Repetitiveness is classified as
When the body part is
idle most of the time
Very Low
frequently pausing, waiting for equipment
Low
in steady motion
Medium
in rapid motion
High
in constant rapid motion, difficult to keep up.
Very High
4
Low Repetition

• Greater than 30 seconds per cycle
• OR
• Less than 1000 parts per shift
• OR
• A fundamental cycle time that is less than
• 50 of the total cycle time

5
High Repetition

• Less than 30 seconds per cycle
• OR
• Greater than 1000 parts per shift
• OR
• A fundamental cycle time exceeds 50
• of the total cycle time

6
What is Repetitive ? (continued)
Body Part
Repetitions Per Minute
Shoulder
More than 2 1/2
Upper Arm/Elbow
More than 10
Forearm/Wrist
More than 10
Finger
More than 200
Kilbom, A. 1994. Int. J of Ind. Erg. 1459-86
7
Repetition
8
Risk FactorRepetition
9
Repetition
Packets unstapled and counted7,000-9,000 pages
counted per day by hand
10
Repetition
11
Forceful Exertion
The force exerted by the body to perform an
action. The higher the force, the greater the
potential to develop injuries.
12
Forceful Exertion
13
Forceful Exertion
14
Forceful Exertion
15
Direct Mechanical Pressure
The force exerted by the environment (tools,
tables, guarding, protective equipment, etc.) on
the body.
16
Direct Mechanical Pressure
17
Direct Mechanical Pressure
18
Direct Mechanical Pressure
19
Direct Mechanical Pressure
20
Direct Mechanical Pressure
21
Direct Mechanical Pressure-Vibration
22
Vibration

• Hand-Arm Segmental

generally 40 - 300 Hz are a concern

• Whole-Body

generally lt 40 Hz are a concern
Is this well designed tool?
23
Hand/Arm Vibration

• Exposure to vibration from hand held power tools
• Vibration appears to contribute to nearly all
  chronic nerve and tendon disorders of the upper
  extremity
• Vibration exposure may accelerate the onset of
  CTDs various tissues and joints are subject to
  different frequencies
• Vibrations may require the hand to exert greater
  grip force
• The onset of disorders appears to be decisively
  frequency dependent

24
Direct Mechanical Pressure-Vibration
25
Direct Mechanical Pressure-Vibration
26
Awkward PostureTrue Neutral
27
Awkward PostureNeck
28
Awkward PostureSit/Stand Neutral
29
Awkward Posture Non-Neutral Sit/Stand
30
Risk Factor Awkward Posture Hands-Fingers
31
Awkward PostureWrist
32
Awkward Posture Wrist
33
Awkward PostureElbow
34
Awkward Postures

• Forearm / Elbow

Pronation
Supination
Flexion
35
Awkward Postures

• Shoulder

Hyperextension
Flexion
Abduction
36
Elbow elevation/rotation
37
Awkward PostureElbow
38
Awkward Posture Elbow
39
Awkward PostureShoulder
40
Awkward Posture Shoulder
41
Awkward Posture Back/Trunk - Bending
42
Awkward Posture Back/Trunk - Bending
43
Awkward Posture Back/Trunk-Reaching
44
Awkward Posture Back/Trunk-Twisting
45
Awkward Posture Back/Trunk-Overhead
46
Awkward PostureLegs/Lower Body
47
Awkward Posture Legs/Lower Body
48
Static Posture
The muscles and other tissues of the body utilize
reserve energy and oxygen when a person performs
a task. Once depleted, the recovery time
increases exponentially with the level of use.
49
Static Posture
50
Static Posture
Resting
Dynamic
Static
blood flow supplied
blood flow needed
blood flow supplied
blood flow needed
blood flow needed
blood flow supplied
51
Static Posture
52
Static Posture
53
Environmental Stressors - Cold
54
Cold Temperatures
55
Environmental Stressors - Heat
56
Environmental Stressors - Light
57
Combined Risk Factors
58
Risk Factor Synergy
Force Frequency
37X
OF POPULAT I ON
6X
4X
1X
Source Silverstein, et al., 1986
59
Individual Risk Factors

• Rheumatoid arthritis
• Endocrinological disorders
• Diabetes mellitus
• Acute Trauma
• Bruises, burns, lacerations
• Vitamin B-6 deficiency
• high doses are toxic
• Wrist size
• Gender
• Pregnancy
• Oral contraceptives
• Weight
• Previous trauma or surgery
• Gynecological surgery
• Oophorectomy (ovariectomy), hysterectomy

60
Historical / TrendAnalysis
Records Analyses help identify prioritize jobs
to evaluate.
Injury/Illness Production Personnel Employer/Empl
oyee Records Records Records Survey OSHA
log 300 Seasonal Trends Turn-over Rate Symptoms
survey Incidence Rate Quality Control Absenteeism
Early reporting mechanism Prevalence Rate Model
Changes Grievances Suggestion award
program First-aid logs Bottlenecks Accident
Invest. Material Flow Workers Comp. Plant
Layout
61
Ergonomic Job Analysis

• Ergonomic job analysis identifies the workers
  exposure to ergonomic risk factors in problematic
  jobs by allowing the evaluator to analyze a job.

62
Ergonomic Job Analysis Methods

• Task Analysis
• Checklists
• Video Taping
• Analysis Tools/Guidelines (ex. NIOSH, OSU/BWC,
  Snook, Job Strain Index, RULA)
• Interviews
• Symptom Surveys

63
Ergonomic Job Analysis Benefits

• Formal comparison between job task and human
  capabilities
• Uncovers deficiencies easily overlooked and
  prompts us to ask more questions about the job
  and why it is done a certain way.
• Provides detailed documentation

64
Task Analysis

• An outline or set of instructions for sequenced
  actions to accomplish a task
• Also known as Work, Job, or Methods Analysis
• Objective To identify work methods by individual
  components and evaluate for risk factors.

65
Task Analysis - Benefits

• Formal comparison between task demands and human
  capabilities
• Uncovers deficiencies easily overlooked, and
  prompts us to ask more questions about the job.
  (Why?)
• Provides detailed documentation for
  re-evaluation, training, and comparison to other
  jobs

66
Task AnalysisMajor Steps

• Designate the job to study
• Collect Data (observe, videotape, interview)
• Data Representation
• Documentation on Forms
• Identify risk factors
• Control Measure Formulation

67
Checklists

• Shorthand tools that help to collect and
  organize, as well as, quantify risk factor data.
• Checklists are rarely if ever valid pass/fail
  measurement devices.
• They are best used as comparative gauges.

68
Checklists
Checklists are designed to pinpoint 1) how far
a particular job is from perfect and 2)
what components of the job are available for
improvement.
69
Checklists
Checklists run the spectrum from very detailed to
concise, one-page.
70
Checklists
Very Detailed - Specific questions that rate a
task by the total number of yes answers
Minimum training required - Industry
specific
71
Checklists
One Page - Measure severity of specifically
defined risk factors. Can be used on any
and all tasks in the facility - Detailed
training required.
72
BWC Risk Factor Assessment Form
73
Identical or Similar Motions
BWC Risk Factor Assessment Form Examples
74
Keying
BWC Risk Factor Assessment Form Examples
75
Grip More than 10 pound load
BWC Risk Factor Assessment Form Examples
76
Pinch More than 2 pounds
BWC Risk Factor Assessment Form Examples
77
Neck Twist / Bend
BWC Risk Factor Assessment Form Examples
78
Shoulder Elbow above mid-torso
BWC Risk Factor Assessment Form Examples
79
Forearm Rapid Rotation
BWC Risk Factor Assessment Form Examples
80
Wrist Bend/Deviate
BWC Risk Factor Assessment Form Examples
81
Fingers Forceful Gripping
BWC Risk Factor Assessment Form Examples
82
Extended arm reaches
BWC Risk Factor Assessment Form Examples
83
Reaching Overhead
BWC Risk Factor Assessment Form Examples
84
Reaching Behind Torso
BWC Risk Factor Assessment Form Examples
85
Hard Objects Pressed into skin
BWC Risk Factor Assessment Form Examples
86
Using Palm as a Hammer
BWC Risk Factor Assessment Form Examples
87
Vibration
BWC Risk Factor Assessment Form Examples
88
Mild Forward or Lateral Bending
BWC Risk Factor Assessment Form Examples
89
Severe Forward Bending
BWC Risk Factor Assessment Form Examples
90
Backward Bending
BWC Risk Factor Assessment Form Examples
91
Twisting
BWC Risk Factor Assessment Form Examples
92
Prolonged Sitting without adequate support
BWC Risk Factor Assessment Form Examples
93
Standing Stationary
BWC Risk Factor Assessment Form Examples
94
Kneeling / Squatting
BWC Risk Factor Assessment Form Examples
95
Ankle Extension
BWC Risk Factor Assessment Form Examples
96
Hard Objects Press into skin
BWC Risk Factor Assessment Form Examples
97
Using Knee as a Hammer
BWC Risk Factor Assessment Form Examples
98
Vibration
BWC Risk Factor Assessment Form Examples
99
Push / Pull
BWC Risk Factor Assessment Form Examples
100
Manual Material Handling
BWC Risk Factor Assessment Form Examples
101
Lighting
BWC Risk Factor Assessment Form Examples
102
Cold Temperature
BWC Risk Factor Assessment Form Examples
103
Class Exercise
BWC Risk Factor Assessment Form Exercise
104
QEC

• Quick Exposure Check

105
Back posture (A1-A3)

• Almost neutral

Standing Sitting Twisting
QEC Instructions
106
Back posture (A1-A3)

• Moderately flexed or twisted

Standing Sitting Twisting
QEC Instructions
107
Back posture (A1-A3)

• Excessively flexed or twisted

Standing Sitting Twisting
QEC Instructions
108
Back movement (B1-B5)

• For manual material handling tasks, assess B1-B3.
  This refers to how often the person needs to
  bend, rotate his/her back when performing the
  task. Several back movements may happen within
  one task cycle.
• For tasks other then manual handling, such as
  sedentary work or repetitive tasks performed in
  standing or seated position, ignore B1-B3 and
  assess B4-B5.

QEC Instructions
109
Shoulder/arm posture (C1-C3)

• Assessment should be made when the shoulder/arm
  is most heavily loaded during work, but not
  necessarily at the same time as the back is
  assessed.

QEC Instructions
110
Shoulder/arm movement (D1-D3)

• Infrequent if there is no regular motion
  pattern.
• Frequent if there is a regular motion pattern
  with some short pauses.
• Very frequent if there is a regular continuous
  motion pattern during work.

QEC Instructions
111
Wrist/hand posture (E1-E2)
Almost neutral lt 15 degrees
Deviated gt 15 degrees
QEC Instructions
112
Wrist/hand movement (F1-F3)

• This refers to the movement of the wrist/hand and
  forearm, excluding the movement of the fingers.

QEC Instructions
113
Neck movement (G1-G3)

• The neck can be considered to be excessively
  bent or twisted if it is bent or twisted at an
  obvious angle (or more than 20?) relative to the
  torso.

QEC Instructions
114
QEC Exercise
QEC Instructions
115
Task Analysis

• An outline or set of instructions for sequenced
  actions to accomplish a task
• Also known as Work, Job, or Methods Analysis
• Objective To identify work methods by individual
  components and evaluate for risk factors.

116
Video Taping Techniques

• The basics
• name of company and location of taping
• date of taping
• videographers name
• either name the task being recorded during taping
  or keep track on paper.

117
Video Taping Techniques

• Taping
• Take a full body shot of the employee. Include
  the surface on which the employee is standing or
  seated.
• If several employees are performing the same
  task, tape at least three employees.
• Tape the worst case, best case, and the
  average situations.
• Following the long shot, zoom in to focus on the
  area or function of greatest concern, if known.
• Video tape the employee from all sides, if
  possible (front, back, both sides)

118
Video Taping Techniques

• Taping Duration
• Videotape each task long enough to show what is
  being evaluated.
• Important to tape at least one cycle.
• For cycle times less than 30 seconds, tape 10
  cycles.
• For cycles greater than 30 seconds, tape at least
  one cycle.

119
1991 NIOSH Lifting Model
Variables H horizontal location from
midpoint between ankles to the center of
the load at origin of lift (inches) V vertical
location of the hands at the beginning of lift
measured from floor to hands (inches) D
vertical travel distance from origin to
destination (inches) F average frequency of
lift (lifts/minute) A angle of asymmetry -
angular measure of how far the object is
displaced from the front of the workers body
at the beginning of the lift (degrees)
D
A
V
H
120
1991 NIOSH Lifting Model
Calculations, where LC load constant 51
lbs HM horizontal multiplier 10/H VM
vertical multiplier 1- (0.0075 V-30 ) DM
distance multiplier 0.82 (1.8/D) AM
asymmetry multiplier 1 - (0.0032 x A) FM
frequency multiplier FROM TABLE CM coupling
multiplier FROM TABLE
therefore RWL Recommended Weight Limit
(LC)(HM)(VM)(DM)(AM)(FM)(CM) (the amount
of weight that nearly all healthy workers could
lift for up to 8 hours without an increased risk
for developing low back pain)
LI lifting index Load Weight/RWL
1.0ltLIlt3.0 changes should be considered - some
workers may be at risk LI gt3.0
changes may be needed immediately- nearly all
workers appear to be at
increased risk
121
1991 NIOSH Lifting
The 1991 equation does not apply for any task
that includes lifting/lowering

• with one hand
• for gt 8 hours
• while seated kneeling
• in a restricted work space
• unstable objects
• while carrying, pushing, or pulling
• with wheelbarrows or shovels
• with high speed motion(faster than 30in/sec
• with unreasonable foot/floor coupling (lt0.4 cof)
• in an unfavorable environment ( temp lt66 or gt79
  F)

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123
Maximum acceptable forces for the 90th Percentile
(Snook and Ciriello, 1991) Pushing Limits
Hand Height Push Distance Frequency Initial Force Sustained Force
Male Waist 25 1push/30 min. 55 lbs. 33 lbs.
Female Waist 25 1push/30 min. 42 lbs. 20 lbs.
Male Shoulder 25 1push/30 min. 48 lbs. 35 lbs.
Female Shoulder 25 1push/30 min. 42 lbs. 20 lbs.
Male Waist 7 1push/30 min. 62 lbs. 42 lbs.
Female Waist 7 1push/30 min. 46 lbs. 24 lbs.
Male Shoulder 7 1push/30 min. 57 lbs. 40 lbs.
Female Shoulder 7 1push/30 min. 46 lbs. 26 lbs.
124
Liberty Mutual Tables for Pulling(Snooks Tables)
125
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Manual pulling of cart
Push force 30.2 lbs.
49from floor to hands
127
Snooks Table
1st Scenario 2nd Scenario 3rd Scenario
Percent Capable 90 female 90 female 90 female

Handle Height 53.1 inches 35.0 inches 53.1 inches

Pushing Distance 200 feet 200 feet 200 feet

Frequency of Push 1 push/ 8 hr. 1 push/8 hr. 1 push/ 5 min.

Initial Force 33 lbs 35 lbs 29 lbs
Sustained Force 13 lbs 13 lbs 9 lbs
128

• The purpose for this assessment is to compare
• lifting parameters for loading PC equipment
• from a cart to a car trunk
• from the cart to the back seat of a car and
• from the cart to the back of a van

What is the MOST stressful lifting task/scenario?
Should the organization buy a new van?
129
Scenario 1 Lift box from cart to car trunk
CLI 5.6     Object Wt. Object Wt. Hand Location (inches) Hand Location (inches) Hand Location (inches) Hand Location (inches) Asymmetry Asymmetry
1991 Guide 1991 Guide 1981 Guide 1981 Guide (lbs) (lbs) Origin Origin Destination Destination (degrees) (degrees)
RWL LI AL MPL L (avg) L (max) H V H V Orig Dest
10.5 5.6 11.2 33.7 44.0 59.0 33.0 10.0 34.0 29.0 0 10
Additional model parameters Duration of task
1.0 hour Frequency of lifting task 0
lifts/min. Coupling Poor
130
Scenario 2 Lift box from cart to back seat
CLI 6.8          Object Wt.      Object Wt. Hand Location (inches) Hand Location (inches) Hand Location (inches) Hand Location (inches) Asymmetry Asymmetry
1991 Guide 1991 Guide 1981 Guide 1981 Guide (lbs) (lbs) Origin Origin Destination Destination (degrees) (degrees)
 RWL LI AL MPL L (avg) L (max) H V H V Orig Dest
8.6 6.8 10.9 32.8 44.0 59.0 33.0 10.0 38.0 32.0 0 60
Additional model parameters Duration of task
1.0 hour Frequency of lifting task 0
lifts/min. Coupling Poor
131
Scenario 3 Lift box from cart to van trunk
CLI 5.8          Object Wt.      Object Wt. Hand Location (inches) Hand Location (inches) Hand Location (inches) Hand Location (inches) Asymmetry Asymmetry
1991 Guide 1991 Guide 1981 Guide 1981 Guide (lbs) (lbs) Origin Origin Destination Destination (degrees) (degrees)
 RWL LI AL MPL L (avg) L (max) H V H V Orig Dest
10.2 5.8 10.7 32.2 44.0 59.0 33.0 10.0 30.0 35.0 0 10
Additional model parameters Duration of task
1.0 hour Frequency of lifting task 0
lifts/min. Coupling Poor
132
Discussion

•  This task is considered hazardous and only
  engineering
• controls are recommended.
• The calculated values are conservative multiple
  loading
• (lifting more than one box per lift), increase
  in frequency,
• lifting for move than one hour, and any
  greater asymmetry
• associated with the lift, will only increase
  these calculated
• values.
• The worst case scenario is lifting from cart to
  backseat of
• car.
• Lifting to the car trunk or the trunk of a van,
  appears to
• provide similar exposure for injury.

133
Discussion

• It is recommended that the vertical origin be
  elevated closer to 30 inches. This would have the
  following impact (used van data).
•  

CLI 4.4          Object Wt.      Object Wt. Hand Location (inches) Hand Location (inches) Hand Location (inches) Hand Location (inches) Asymmetry Asymmetry
1991 Guide 1991 Guide 1981 Guide 1981 Guide (lbs) (lbs) Origin Origin Destination Destination (degrees) (degrees)
 RWL LI AL MPL L (avg) L (max) H V H V Orig Dest
13.5 4.4 16.4 49.1 44.0 59.0 33.0 30.0 30.0 35.0 0 10
Additional model parameters Duration of task
1.0 hour Frequency of lifting task 0
lifts/min. Coupling Poor

• Providing a higher unloading height would
  require an adjustable cart.

www.tollydolly.com
134
Discussion

• The horizontal distances cannot be reduced, due
  to
• box dimensions.
• Using two employees instead of one to make
  these
• computer deliveries is suggested based on the
• significant difference of the calculated AL
  and MPL
• values compared to the actual weight(s)
  lifted.
• Providing handles on the boxes will improve the
  LI
• and RWL, however, both values will remain
  greater
• than recommended by the 1991 model.
• Loading to the van is the only option that may
  allow
• the employee to slide the box from an
  adjustable cart
• into the trunk.  Sliding motions are 4-5 times
  less
• stressful than lifting tasks.
• Consider a lift gate for the van to allow
  adjustability in work
• height.

135
Municipality

• Situation
• Heavy lifting of manhole covers, sewer grates and
  equipment create loads on the spine, increasing
  risk of injury.
• Heavy jackhammers create loads on the spine, and
  expose operators to hand and arm vibration.

136
Primary work tasks

• Essential function is to install, maintain,
  repair and service water distribution and sewage
  facilities. Other tasks include
• Excavating / backfilling trenches and culverts
• Installing, repairing and replacing water and
  sewer mains
• Joining and caulking pipelines
• Repairing valves and hydrants
• Drilling / installing taps in mains
• Performing street repairs through use of land
  plats, maps and diagrams.

137
Municipality Job modifications

• Cranes

138
Municipality Job modifications

• Lift gates on trucks

139
Municipality Job modifications

• Lightweight / low-vibration jackhammers

140
Municipality

• Results
• Incidence rate, lost days rate, and restricted
  days rate decreased.
• 1 person can now perform some tasks that
  previously required 2 people and with less risk.

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144
Stock Room
One case of paper weighs 52 lbs
145
NIOSH Model
CLI 15.3     Object Wt. Object Wt. Hand Location (inches) Hand Location (inches) Hand Location (inches) Hand Location (inches) Asymmetry Asymmetry Freq
Task 1991 Guide 1991 Guide 1981 Guide 1981 Guide (lbs) (lbs) Origin Origin Destination Destination (degrees) (degrees) (/min)
No. RWL LI AL MPL L (avg) L (max) H V H V Orig Dest F
1 8.4 6.2 8.3 25.0 52.0 52.0 29.0 50.0 29.0 10.0 15 30 5.0
2 9.6 5.4 10.3 30.9 52.0 52.0 29.0 40.0 29.0 20.0 15 30 5.0
3 11.4 4.5 12.4 37.2 52.0 52.0 29.0 30.0 29.0 30.0 15 30 5.0
4 9.6 5.4 9.5 28.5 52.0 52.0 29.0 20.0 29.0 40.0 15 30 5.0
5 8.9 5.9 8.4 25.3 52.0 52.0 29.0 10.0 29.0 30.0 15 30 5.0
Additional model input With duration based on
less than 1 hour per day With coupling considered
poor
146
Solution
This task is considered hazardous and only
engineering controls are recommended.
147
Pushing of cart
Push force 23-75lbs.
Handle height 46 (from floor to hands)
148
Snooks Table
PULL/PUSH TWO HANDED Scenario 1 PUSH Scenario 2 PUSH Scenario 3 PUSH
Gender Male Male Female
Height of hands while performing work 37inches 57 inches 53 inches
Percentage of population capable of performing the push 90 90 90
Distance of push 25 feet 25 feet 25feet
Frequency of push 1 push every 30 minutes 1 push every 30 minutes 1 push every 30 minutes
Maximum Acceptable INITIAL force 55 lbs 48 lbs 42 lbs
Maximum Acceptable SUSTAINED force 13 lbs 35 lbs 20 lbs
149
Possible Solutions

• Modify the wheels- larger diameter
• Reduce the weight of a loaded/full cart
• Purchase an electric cart
• Ensure stacked cart height does not interfere
  with visual tasks