Chronic Exposure Index Model to Assess Ergonomic Risk Factor Related to Upper Extremity Musculoskeletal Disorders
71 • Unsuitable lighting low or
high • Exposure to heat
• Carelessly • Economic problems
• Background of UEMSDs • Localized compression on
upper limb • Lack of training
• Secondary job • Reach limit
• Clearance • Humidity
• Poor size or shape of parts • Presenting vibration
• Exposure to cold • Presenting noise
• Low experience • Familiar problems
• Contact stress • Sharpness of object surface
• Rapid twistingturning movements
• Overtime • Slippery level
• Poor packaged goods or poor handles
• Chemical components and poisons
• Hand-arm vibrations
Then, the scores are added and the corresponding multiplier factor is determined Table 10, which was calculated from 15 and 16 studies using the
OCRA method 10.
4. Development of the CEI
UEMSDs are generally agreed to be a multi-factorial occupational problem 24. Many epidemiological studies have linked development of UEMSDs to various risk
factors 25, 26, 27, 28, which have been classified into physical 29, psychosocialorganizational 30, 31, 32, and individual 33 occupational risk
factors.
Several ergonomic techniques have been developed to assess exposure UEMSD risk factors 34. Many of the posture–based observational techniques which have
been provided are only strictly applicable in very limited circumstances and have shortcomings and limitations. Based on these findings and current techniques, a
strategy and policy was developed to obtain a CEI which:
a Is applicable to the complete range of manual tasks; b Provides an integrated assessment of various risk factors;
c Provides an independent assessment of disorder risk to different body regions; dProvides an overall risk assessment which allows prioritisation of tasks and
submits suggested action levels; eFacilitates effective targeting of controls by providing an indication the relative
severity of different risk factors within a task; f Is suitable for use by workplace staff with minimal training and equipment;
g Is quick and easy to use; and h Can identify high risk manual handling and repetitive tasks
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Table 10. Elements for determining the multiplier factor for effective items EI
Score of effective items 0 1-4 5-8
9-12 12
Multiplier factor 1 1.5 2 2.5 3
4.1. Applicability of the CEI
The proposed CEI model has been applied successfully in several studies performed by the author unpublished reports; this success shows that it can be
used in the study of many repetitive single or multiple tasks without any limitations. In most cases the aim of studies has been to identify and assess the risk factors of
UEMSDs and injuries for individual employees. A more detailed and general purpose was to assay, measure and investigate the reliability and validity of various
survey risk factors involving in calculating the CEI Score. The studies have been performed in different fields, including weaving and textile industries,
manufacturing industries, carpentry, steel industry, post offices, service industry, electronic industry, shopping and marketing, agriculture and farming industry,
tailoring and sewing, hair styling, baking, and bricklaying.
4.1. Applicability of the CEI
The proposed CEI model has been applied successfully in several studies performed by the author unpublished reports; this success shows that it can be
used in the study of many repetitive single or multiple tasks without any limitations. In most cases the aim of studies has been to identify and assess the risk factors of
UEMSDs and injuries for individual employees. A more detailed and general purpose was to assay, measure and investigate the reliability and validity of various
survey risk factors involving in calculating the
4.2. Reliability and validity tests of the CEI 4.2.1. Inter-observer reliability test of the assessment items
Inter-observer assessment reliability Table 11 was assessed to identify possible sources of error in the reliability assessment test process. In this test, 31 various tasks
were randomly selected from 31 different jobs involving manual handling tasks with varied part load weights. The ergonomic field study assessed static and
repetitive tasks; highly repetitive tasks; repetitive tasks with low, moderate and high force exertions; sedentary or standing tasks; and non- repetitive tasks with low,
moderate and high force exertions. Video-tape recordings were viewed in slow motion to confirm the assessment of the observer. Several pilot tests quantified that
assessment durations of 5-7 minutes are sufficient to complete the assessment
