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Evaluation of workEvaluation of work--related musculoskeletal related musculoskeletal
disorder risk of forestry workers: a case study disorder risk of forestry workers: a case study
using OWASusing OWAS
Angela Calvo Angela Calvo -- ItalyItaly
15. Arbeitswissenschaftliches Seminar - 15th Seminar of Work Science
Evaluation of work-related musculoskeletal disorder risk of forestry workers: a case study using OWAS
The 10 most important emerging physical risks identified by the Risk Observatory of the European Agency for Health and Safety (2002-2006)
4,57 4,56 4,5 4,43 4,42 4,4 4,38 4,35 4,21 4,17
0
1
2
3
4
5
Lack
of ph
ysica
l acti
vity
Vibrati
on&aw
k. po
sture
Thermal
risks
x low
-statu
s
MSD&psich
osoc
ial risk
Multi-fac
torial ri
sks
Thermal
disco
mfort
Vibrati
on&mus
cular
work
Human-m
achin
e inter
face
Long
-stand
ing er
gon.ris
ks
Expos
ure to
UV ra
diatio
n
Like
rt s
cale
val
ues
RISKS
MSD disorders
Thermal discomfort
Vibration and awkward postures
Noise
Long-standingergonomic risks
Vibration and muscular work
Dangerous machineries
Forestry operators’ main risks
Evaluation of work-related musculoskeletal disorder risk of forestry workers: a case study using OWAS
MANUAL WORK LOAD
MSD RISKS
Evaluation of work-related musculoskeletal disorder risk of forestry workers: a case study using OWAS
MSD risk evaluation
• OWAS – Ovako Working-posture Analysis System;
• NIOSH – National Institute of Occupational Society and Health;
• OSHA – Occupational Safety and Health Administration;
• PATH – Posture, Activity, Tools and Handling.
Some known systems
Evaluation of work-related musculoskeletal disorder risk of forestry workers: a case study using OWAS
THE NIOSH METHODOLOGY
NIOSH – National Institute of Occupation Society and Health
RWL: Reccomended Weight Limit
RWL=CP*A*B*C*D*E*F*G*H (de-multiplicative factors)
Lifting Index LI
LI = Weight to be moved
RWL
Evaluation of work-related musculoskeletal disorder risk of forestry workers: a case study using OWAS
THE OSHA METHODOLOGY
OSHA – Occupational Safety and Health Administration
Guidelines
Integrated system for the work organization
Risk evaluation
Procedures to limit the riskexposure
Evaluation of work-related musculoskeletal disorder risk of forestry workers: a case study using OWAS
PATH METHODOLOGY
PATH – Posture, Activity, Tools and Handling
Ergonomic risk
Positions:
5 for back
2 for neck
3 for arms
10 for legs
Used tool
Activitytype
Manual work load
Evaluation of work-related musculoskeletal disorder risk of forestry workers: a case study using OWAS
OWAS METHODOLOGY
252 configurations
4 for back
3 for arms
7 for legs
3 for the weight
Evaluation of work-related musculoskeletal disorder risk of forestry workers: a case study using OWAS
Evaluation of work-related musculoskeletal disorder risk of forestry workers: a case study using OWAS
OWAS positions
Back Arms Legs Load
Bendingback
Standing back
Twistingback
Twistingand bendingback
Armsunder the shoulder
One armover the shoulder
Both the armsover the shoulder
Sit
Standing weighton 2 legs
Standing weighton 1 leg
Standing kneesbent
Standing, weight on 1 leg, knee bent
Kneeling, 1 or 2 kneestouchingthe ground
Walking
Lessthen 10 kg
Between10 and 20 kg
More then 10 kg
Risk classes
252 configurations
Class 1: natural position
Class 2: positions which may be dangerous
Class 3: dangerous positions
Class 4: very dangerous positions
4 risk classes
Evaluation of work-related musculoskeletal disorder risk of forestry workers: a case study using OWAS
Evaluation of work-related musculoskeletal disorder risk of forestry workers: a case study using OWAS
Legs-w
eight
back
arms
3372Walking, 10-20 kg
load, twistingback,
both the arms
over the shoulder
1141Standing
kneesbent, <10kg load,
standing back, arms
under the shoulder
2113Sitting, >20kg load,
bendingback, armsunder
the shoulder
2313Sitting, >20kg load,
bendingback,
both the arms
over the shoulder
OWAS method: the index risk
( ) ( ) ( ) ( )[ ] 1004321 ⋅⋅+⋅+⋅+⋅= dcbaI
a, b, c, d : frequency rates into classes 1, 2, 3 e 4.
Index risk (I)
Risk class Frequency
I = 100, minimum risk
I = 400, maximum risk
Evaluation of work-related musculoskeletal disorder risk of forestry workers: a case study using OWAS
Forestry yards location:• Buthier (Gran S. Bernard)• Ozein (Cogne)•1500 meters over the sea level, in a very sloped area (>30°), slippery and uneven ground
Analized works• cut of the tree;• manual tree extraction;• skidding and stacking of the logs.
Evaluation of work-related musculoskeletal disorder risk of forestry workers: a case study using OWAS
5 operators considered (age:30-50)
Cut phase: 1 operator
Used tools: 6 kg chainsaw, hoe and 1,5 kg peavey
Position: the operator is standing or with the knees bent, bending and twisting back, the arms always under the shoulder
Risks: noise, vibration and muscularwork, exhaust gas, position and chainsaw potential danger
Cut mark realization: 4131posture, class 2
Evaluation of work-related musculoskeletal disorder risk of forestry workers: a case study using OWAS
Manual tree extraction: 4 operators
Manual extraction: 4173 posture, class 4
Used tools: 2 kg short-handled timber hoe to movelogs (3-7m long and 10-30cm diameter)
Position: the operators workswith the bending or twistingback, standing with the weighton one leg or knee bent, the arms under the shoulder and moved weight > 20 kg
Risks: awkward postures, thermaldiscomfort, heavy muscular work
Evaluation of work-related musculoskeletal disorder risk of forestry workers: a case study using OWAS
Skidding and log stacking: 4 operators. Phase 1
Used tools: hoe, tractor and pulley with chains
Position: 2 operators works withthe bending back, standing withthe weight on one leg or kneebent, the arms under the shoulder
Risks for the tractor driver: noise and vibration
Risk for the operators: awkward postures, thermal discomfort, noise
Evaluation of work-related musculoskeletal disorder risk of forestry workers: a case study using OWAS
Skidding and log stacking: 4 operators+tractor driver
Stacking: 2143 posture, class 3
Used tools: none. 2-3 operatorsstack the logs manually
Position: bending back at the first time, then standing, knees bendingat the beginning, arms under the shoulder.
Risks: heavy manual work load, thermal discomfort,
Evaluation of work-related musculoskeletal disorder risk of forestry workers: a case study using OWAS
Skidding and log stacking: 4 operators. Phase II
Data collection and elaboration
32123P3G2B1S220,26340,527429
32143P3G4B1S251,874103,748828
32143P3G4B1S220,26340,527527
32143P3G4B1S241,56383,127726
32143P3G4B1S241,56383,127825
44143P3G4B1S477,931155,862924
32142P2G4B1S212,82925,659423
…………………………
…………………………
32143P3G4B1S221,38242,76564
32141P1G4B1S26,75413,50963
32143P3G4B1S220,26340,52792
32143P3G4B1S225,65951,31861
RiskClass
Owascode
Weight
codeLegsArmsBack
Movedweight
(kg)
Log weight
(kg)Time (s)Sample
For each phase and for each operator, all the postures and the movedweight have been evaluated
825 risk classes values have been calculated
Evaluation of work-related musculoskeletal disorder risk of forestry workers: a case study using OWAS
THE WINOWAS Software
The WINOWAS software haas beenused for the data analysis (frequencyrates and risk classes evaluation)
Evaluation of work-related musculoskeletal disorder risk of forestry workers: a case study using OWAS
Results
Considering the index risk between 100 and 400 and 4 riskclasses from 1 to 4:
Cut phase: IR = 287 (frequency rate in class 3+4: 50%)
Manual extraction: IR = 311 (frequency rate in class 3+4: 77%)
Skidding+manual log stacking: IR = 300 (frequency in class 3+4: 91%)
Evaluation of work-related musculoskeletal disorder risk of forestry workers: a case study using OWAS
Results: manual extraction
Evaluation of work-related musculoskeletal disorder risk of forestry workers: a case study using OWAS
0
10
20
30
40
50
60
Operator 1 Operator 2 Operator 3 Operator 4
frequ
ency
rate
(%)
Class 1Class 2Class 3Class 4
Class1: 1%. Class2: 22%. Class3: 42%. Class4: 35%
CONCLUSIONSAll the operations in both the yards are characterized by anhigh index risk value
The more critical operation is the manual extraction, with the highest frequency rate in class 4: therefore, the unfavourable environment conditions do not permit the use of machineries
Index risk values
287
311
300
CutManual extraction Log stock
Evaluation of work-related musculoskeletal disorder risk of forestry workers: a case study using OWAS
CONCLUSIONS(continue)
Some indications to limit the MSD risk for forestry workers:
• augment the pause frequency
•train and inform the operators about the correct positions and load methods
•reduce the moved log dimension
Evaluation of work-related musculoskeletal disorder risk of forestry workers: a case study using OWAS
CONCLUSIONS(continue)
• use wincheswhenever it’s possible
Evaluation of work-related musculoskeletal disorder risk of forestry workers: a case study using OWAS
CONCLUSIONS(continue)
• use a sled for movinglogs
Evaluation of work-related musculoskeletal disorder risk of forestry workers: a case study using OWAS
CONCLUSIONS(continue)
•When it is possible, use a tractor with hydraulic pliers for stacking
Evaluation of work-related musculoskeletal disorder risk of forestry workers: a case study using OWAS
Some results about the vibrations surveied in the same forestryyards
Vibrationtransmitted to the whole-body
Vibrationtransmitted to the hand-arm system
0,901Tractor driverDaily value A(8) ms-2Operator
A(8) daily limits (2002/44 Directive): 0.5-1.15 ms-2 for the wholebody, 2.5-5 ms-2 for the hand-arm
Operation Daily value A(8) ms-2
Cut (right) 6,5Cut (left) 5,3Cut (right) 6,1Cut (left) 3,7Cut (right) 4,4Cut (left) 5,4
Necessity to consider:1. Vibration
And2. Awkward postures
And3. Muscular work
And4. Thermal discomfort
Togheter(as emerging physical risks declared)
Evaluation of work-related musculoskeletal disorder risk of forestry workers: a case study using OWAS
Thank you forthe attention
Evaluation of workEvaluation of work--related musculoskeletal related musculoskeletal
disorder risk of forestry workers: a case study disorder risk of forestry workers: a case study
using OWASusing OWAS
Angela Calvo, DEIAFA, Italy, [email protected]