The Effect of Simultaneous Postural Stress and Noise Exposure on Strain Index Number Among the Machinery Women Aged 25 ? 30 Years old in Gas Supply Parts Manufactories


Nasrin Zolfaghari Nejhad 1 , Ali Khavanin ORCID 2 , * , Shahram Vosoughi 3

1 Department of Occupational Hygiene, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, IR Iran

2 Department of Occupational Health and Safety, Faculty of Medicine, Tarbiat Modares University, Tehran, IR Iran

3 Department of Health Sciences, Faculty of Health, Shahid Beheshti University of Medical Sciences, Tehran, IR Iran

How to Cite: Zolfaghari Nejhad N, Khavanin A, Vosoughi S. The Effect of Simultaneous Postural Stress and Noise Exposure on Strain Index Number Among the Machinery Women Aged 25 ? 30 Years old in Gas Supply Parts Manufactories, Health Scope. Online ahead of Print ; 4(2):23602. doi: 10.17795/jhealthscope-23602.


Health Scope: 4 (2); 23602
Published Online: May 1, 2015
Article Type: Research Article
Received: September 15, 2014
Accepted: January 21, 2015


Background: Work-related musculoskeletal disorder in upper-limbs (WRMSDs-UL) is one of the major complaints among the female machinists in gas supply parts manufactories, in some of which the noise reaches 85 dB and beyond.

Objectives: The most important aim of this study was to evaluate the effects of noise and postural stress on strain index (SI) among these workers.

Materials and Methods: The sample size was set at 50 subjects, comprising of two study groups; group 1 were exposed to noise ? 85 dB, group 2 were exposed to noise < 85 dB, while the official workers were selected as the control group. A Nordic-style questionnaire was used to collect information. Postures were assessed by observing each task, and then SI and quick exposure check (QEC) checklists were completed. The variability of effort intensity was measured by recording the subjects heart rate during her work and also, a sport tester machine was used for this aim. The Borg scale and then SI were calculated. Noise was measured by sound level meter and noise dosimeter, according to noise type. Data analysis was performed by using the Mann-Whitney, Kruskal-Wallis, one-way ANOVA, Spearman and Pearson correlation in SPSS (ver. 16) software.

Results: There was no significant difference between work experience, age, dominant hand and marital status in the target groups (P > 0.05). Results showed a significant statistical relation between work experience and neck pain, shoulders pain and wrist/hand pain. They showed that there existed a different strain index between two groups, although not statistically significant. The Mann-Whitney test showed that there was a significant difference between the two groups from QEC posture score. Spearman correlation coefficient proved that QEC rating is directly related to the value of the SI.

Conclusions: Postural stress among female machinists can increase the level of SI to fairly risky and dangerous. Also, changes in rating hand/wrist QEC scores with hand/wrist SI score were proportional in the studied samples. The SI can increase under the influence of noise above 85 dB, although it is not statistically significant.

© 2015, Author(s). This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License ( which permits copy and redistribute the material just in noncommercial usages, provided the original work is properly cited.

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