Evaluation of work-related related musculoskeletal disorder risk of forestry workers: a case study using OWAS

Transcription

1 15. Arbeitswissenschaftliches Seminar - 15th Seminar of Work Science Evaluation of work-related related musculoskeletal disorder risk of forestry workers: a case study using OWAS Angela Calvo - Italy

2 The 10 most important emerging physical risks identified by the Risk Observatory of the European Agency for Health and Safety ( ) 5 4,57 4,56 4,5 4 4,43 4,42 4,4 4,38 4,35 4,21 4, Likert scale values Lack of physical activity Vibration&awk. posture Thermal risks x low-status MSD&psichosocial risk Multi-factorial risks Thermal discomfort Vibration&muscular work Human-machine interface Long-standing ergon.risks Exposure to UV radiation

3 Forestry operators main risks MSD disorders Thermal discomfort RISKS Vibration and awkward postures Noise Long-standing ergonomic risks Dangerous machineries Vibration and muscular work

4 MANUAL WORK LOAD MSD RISKS

5 MSD risk evaluation Some known systems 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.

6 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

7 THE OSHA METHODOLOGY OSHA Occupational Safety and Health Administration Guidelines Integrated system for the work organization Risk evaluation Procedures to limit the risk exposure

8 PATH METHODOLOGY PATH Posture, Activity, Tools and Handling Positions: 5 for back 2 for neck 3 for arms 10 for legs Ergonomic risk Used tool Manual work load Activity type

9 OWAS METHODOLOGY 252 configurations 4 for back 3 for the weight 3 for arms 7 for legs

10 OWAS positions Back Arms Legs Load Standing back Arms under the shoulder Sit Standing, weight on 1 leg, knee bent Less then 10 kg Bending back One arm over the shoulder Standing weight on 2 legs Kneeling, 1 or 2 knees touching the ground Between 10 and 20 kg Twisting back Both the arms over the shoulder Standing weight on 1 leg Walking More then 10 kg Twisting and bending back Standing knees bent

11 Risk classes 252 configurations 4 risk classes Class 1: natural position Class 2: positions which may be dangerous Class 3: dangerous positions Class 4: very dangerous positions

12 back arms Legs - weight 1141 Standing knees bent, <10kg load, standing back, arms under the shoulder 2113 Sitting, >20kg load, bending back, arms under the shoulder 2313 Sitting, >20kg load, bending back, both the arms over the shoulder 3372 Walking, kg load, twisting back, both the arms over the shoulder

13 OWAS method: the index risk Index risk (I) Risk class Frequency I [( a 1) + ( b 2) + ( c 3) + ( 4) ] 100 = d a, b, c, d : frequency rates into classes 1, 2, 3 e 4. I = 100, minimum risk I = 400, maximum risk

14 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. 5 operators considered (age:30-50)

15 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 muscular work, exhaust gas, position and chainsaw potential danger Cut mark realization: 4131 posture, class 2

16 Used tools: 2 kg shorthandled timber hoe to move logs (3-7m long and 10-30cm diameter) Position: the operators works with the bending or twisting back, standing with the weight on one leg or knee bent, the arms under the shoulder and moved weight > 20 kg Manual tree extraction: 4 operators Risks: awkward postures, thermal discomfort, heavy muscular work Manual extraction: 4173 posture, class 4

17 Skidding and log stacking: 4 operators. Phase 1 Used tools: hoe, tractor and pulley with chains Position: 2 operators works with the bending back, standing with the weight on one leg or knee bent, the arms under the shoulder Risks for the tractor driver: noise and vibration Risk for the operators: awkward postures, thermal discomfort, noise

18 Skidding and log stacking: 4 operators+tractor 4 operators. driver Phase II Used tools: none. 2-3 operators stack the logs manually Position: bending back at the first time, then standing, knees bending at the beginning, arms under the shoulder. Risks: heavy manual work load, thermal discomfort, Stacking: 2143 posture, class 3

19 Data collection and elaboration For each phase and for each operator, all the postures and the moved weight have been evaluated Sample Time (s) Log weight (kg) Moved weight (kg) Back Arms Legs Weig ht code Owas code Risk Class ,318 25,659 S2 B1 G4 P ,527 20,263 S2 B1 G4 P ,509 6,754 S2 B1 G4 P ,765 21,382 S2 B1 G4 P risk classes values have been calculated ,659 12,829 S2 B1 G4 P ,862 77,931 S4 B1 G4 P ,127 41,563 S2 B1 G4 P ,127 41,563 S2 B1 G4 P ,527 20,263 S2 B1 G4 P ,748 51,874 S2 B1 G4 P ,527 20,263 S2 B1 G2 P

20 THE WINOWAS Software The WINOWAS software haas been used for the data analysis (frequency rates and risk classes evaluation)

21 Results Considering the index risk between 100 and 400 and 4 risk classes 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%)

22 60 Results: manual extraction 50 frequency rate (%) Class 1 Class 2 Class 3 Class 4 0 Operator 1 Operator 2 Operator 3 Operator 4 Class1: 1%. Class2: 22%. Class3: 42%. Class4: 35%

23 CONCLUSIONS All the operations in both the yards are characterized by an high index risk value Index risk values Cut Manual extraction Log stock 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

24 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

25 CONCLUSIONS (continue) use winches whenever it s possible

26 CONCLUSIONS (continue) use a sled for moving logs

27 CONCLUSIONS (continue) When it is possible, use a tractor with hydraulic pliers for stacking

28 Some results about the vibrations surveied in the same forestry yards Vibration Necessity to consider: 1. Vibration transmittedtothe Operator Daily value A(8) ms -2 And Tractor driver 0,901 whole-body 2. Awkward postures And 3. Muscular Operation work Daily value A(8) ms -2 Cut And(right) 6,5 Cut (left) 5,3 Vibration 4. Thermal discomfort Cut (right) 6,1 transmittedtothe Togheter Cut (left) 3,7 (as emerging physical risks declared) hand-arm system Cut (right) 4,4 Cut (left) 5,4 A(8) daily limits (2002/44 Directive): ms- 2 for the whole body, ms -2 for the hand-arm

29 Angela Calvo, DEIAFA, Italy, Evaluation of work-related related musculoskeletal disorder risk of forestry workers: a case study using OWAS Thank you for the attention