The Effects of Ergonomic The Effects of Ergonomic Workstation Changes on Workstation Changes on Physical and Psychosocial Physical and Psychosocial Factors in Apparel Factors in Apparel ManufacturingManufacturing

Julianne Natale, Richard Wells, Mardon Frazer, Michael Kerr, Sue Ferrier, Syed Naqvi, Peter Subrata

University of WaterlooUniversity of Western Ontario, Institute for Work and Health,Occupational Health Clinics for Ontario Workers

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PurposePurpose• To compare physical and

psychosocial outcomes of workers who experienced ergonomic workstation changes in two clothing plants to their coworkers who did not

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The Clothing IndustryThe Clothing Industry• Prevalence of WMSDs in sewing

machine operators is higher than any other occupational group

• Sewing is highly repetitious, requiring substantial force and constrained postures

• Strong need for low-cost, quick solutions to reduce these risk factors

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Study IStudy I• Three clothing plants, 600 workers• Workstation changes made in two plants • Questionnaire administered before and

after ergonomic changes• Questionnaire: 16 variables measured

– Productivity– Pain intensity (Von Korff et al. 1992, Smith et al. 2001)– Impact of pain (WLQ: Lerner et al. 1997)– Fatigue on job (Borg 1990, Punnett 1997)– Job content (Karasek 1994, Kerr 2002)

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Measuring Pain IntensityMeasuring Pain IntensityUpper Upper BackBack

Right Shoulder Right Shoulder

Right Upper Right Upper ArmArm

Mid to Mid to Lower BackLower Back

Right Right ForearmForearmRight Right WristWristRight Right HandHand

Right Thigh

Right Lower Leg or Foot

NeckNeck

Left Left ShoulderShoulder

Left Upper Left Upper ArmArm

ButtocksButtocks

Left Left ForearmForearm

Left Left WristWrist

Left HandLeft Hand

Left Left ThighThighLeft Left Lower Lower Leg or Leg or

FootFoot

1=mild2=moderate3=severe4=unbearable

• Pain in last 7 days • Average pain in 6 months • Worst pain in 6 months

••NeckNeck••RUERUE••LUELUE••BackBack••RLERLE••LLELLE

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AnalysisAnalysis• Step I: repeated cross-sectional

analysis

2001 2003

Plant A

Plant B

Plant C

Determine within plant

differences at two time

periods

Participatory Change

Team

Consultant-TypeProcess

Referent

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Workstation ChangesWorkstation ChangesWorkstation Changes

Operations

•Table height adjusted•Table tilted•Chair height adjusted•Backrest adjusted•Large foot pedal installed•Footrest provided•Foot pedal location changed•Anti-fatigue matting provided•Buttonhole size changed•Supply rack lowered•Other

•Manual sewing machine operation•Parts inspect•Tie-up•Button & Iron

96 changes made 41 operators affected (in cohort)

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Manual Measurement: Manual Measurement:

01020304050607080

Shoulder Elbow Wrist Neck Trunk

BeforeAfter

Joints Measured

Aver

age

Join

t An

gle

(deg

rees

) *

*p<0.05

Sub-sample of 16 workstations

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Step I: ResultsStep I: Results

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10121416

Prod

Pain

Int

WLQ

-Tim

e

WLQ

-Phy

s

WLQ

-Men

&So

c

WLQ

-Out

Effo

rt

Fatig

ue-s

hldr

Fatig

ue-N

eck

Fatig

ue-B

ack

Fatig

ue-L

egs

Fatig

ue-F

i/W/F

o

Ove

ral E

ffort

JCQ

-DL

JCQ

-PD

JCQ

-PE

Plant APlant BPlant C

Questionnaire Variable

Nor

mal

ized

Mea

n (%

)

** *

*

*p<0.05

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AnalysisAnalysis• Step II: cohort of workers

Plant A

Plant B

Plant C

2001 2003

Analysis Original Employees

54%

75%

78%

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Step II: ResultsStep II: Results

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10Pr

od

Pain

Int

WLQ

-Tim

e

WLQ

-Phy

s

WLQ

-Men

&So

c

WLQ

-Out

Effo

rt

Fatig

ue-s

hldr

Fatig

ue-N

eck

Fatig

ue-B

ack

Fatig

ue-L

egs

Fatig

ue-F

i/W/F

o

Ove

ral E

ffort

JCQ

-DL

JCQ

-PD

JCQ

-PE

Plant APlant BPlant C

Questionnaire Variable

Nor

mal

ized

Mea

n (%

)

*

*p<0.05

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AnalysisAnalysis• Step III: cohort of workers sub-

grouped

Plant A

Plant B

Plant C

2001 2003

Analysis

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Step III: ResultsStep III: Results

Questionnaire Variable

Nor

mal

ized

Mea

n (%

) *

*p<0.05

No Change ParticipantsNo Change Participants

*

*

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Step III: ResultsStep III: Results

Questionnaire Variable

Nor

mal

ized

Mea

n (%

)

*p<0.05

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101418

Prod

Pain

Int

WLQ

-Tim

e

WLQ

-Phy

s

WLQ

-Men

&So

c

WLQ

-Out

Effo

rt

Fatig

ue-s

hldr

Fatig

ue-N

eck

Fatig

ue-B

ack

Fatig

ue-L

egs

Fatig

ue-F

i/W/F

o

Ove

ral E

ffort

JCQ

-DL

JCQ

-PD

JCQ

-PE

Plant APlant B

*

*

Change ParticipantsChange Participants

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AnalysisAnalysis• Step IV: cohort of “change “workers

grouped across plants

Plant A

Plant B

Plant C

2001 2003

Analysis

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Step IV: ResultsStep IV: Results

-20-18-16-14-12-10

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10Pr

od

Pain

Int

WLQ

-Tim

e

WLQ

-Phy

s

WLQ

-Men

&So

c

WLQ

-Out

Effo

rt

Fatig

ue-s

hldr

Fatig

ue-N

eck

Fatig

ue-B

ack

Fatig

ue-L

egs

Fatig

ue-F

i/W/F

o

Ove

ral E

ffort

JCQ

-DL

JCQ

-PD

JCQ

-PE

Difference

Questionnaire Variable

Nor

mal

ized

Mea

n (%

)

*

*p<0.05

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Study I ConclusionsStudy I Conclusions• Improvement in “Change” group

of workers– Productivity ratio

• Trend towards improvement in– WLQ-time, physical demands– Fatigue: shoulders, neck, fingers,

wrist, forearm– Psychological demands

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SummarySummary• After workstation adjustments and

changes:– only a small positive effect on posture

and RULA scores– an increased productivity ratio observed– trend to decreasing:

• WLQ-time and physical demands• Fatigue at: shoulders, neck, fingers, wrist,

and forearm

• Psychological demands

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Of Note…Of Note…• Interaction of productivity with

physical and psychosocial variables?– Piecework environment– “Ergonomic Pitfall”

• Process continuing with new participatory team at “Consultant” site (B)

• Qualitative analysis and further round of questionnaires in process