International Journal of Occupational Hygiene

Effect of Proprioceptive Exercises along with Ergonomic Intervention on Middle Deltoid and Serratus Anterior Fatigue in Dentists with Non-Specific Chronic Neck Pain

ANAHITA BOLANDIAN, IRAJ ALIMOHAMMADI, BIJAN FOROUGH — Wed, 19 Jan 2022 12:40:10 +0000

There are several risk factors in dentistry that among them repetitive movements, being in a position for a long time due to muscle imbalances, and work-related musculoskeletal disorders which can cause problems such as limited mobility, fatigue, job loss or even changing jobs. Muscle imbalance between the stabilizers and mobilizers of the neck and shoulders in dentists leads to increased work-related disorders, superficial muscle fatigue, and deep muscle atrophy, which in turn, leads to many health problems such as neck pain and disability. To prevent such disorders, a high endurance of the cervical stabilizer muscles is essential for repetitive movements in the distal and shoulder region. In this study, the exercise program, including postural exercises, simultaneous training of shoulder-neck, scapular movements, and co-contraction were designed for 48 dentists. The statistical analysis showed that there was a significant decrease in the median frequency slope of the middle deltoid muscle (p = 0.004) and for the group who received the proprioception training along with posture correction exercises and exercise therapy (p = 0.004). Neck pain increased in the control group who received no exercises, after six weeks (p = 0.165). Six weeks of corrective exercises with ergonomic intervention balance muscles activity and can be used to decrease musculoskeletal disorders and muscle fatigue in person with Non-Specific Chronic Neck Pain.

The Effect of Integrated Management System Establishment on the Safety Performance Indices: A Case Study in a Manufacturing Industry

Wed, 19 Jan 2022 12:47:39 +0000

Safety programs are among the effective factors that may have a key role in upgrading workforce productivity and promotion of qualitative and quantitative indicators of production. The aim of this study was to investigate the effect of integrated management systems (IMS) establishment on safety performance improvement. This study was a retrospective study conducted at the Mazrouf Glass factory in Yazd, Iran. To investigate the effect of IMS establishment on the safety performance during the studied years, indices of injury frequency rate (IFR), injury severity rate (ISR), frequency-severity index (FSI), and Safety T. Score (S.T.S) were used. The paired-samples t-test was used to compare safety indices before and after the establishment of the IMS. The results showed that the establishment of IMS had a meaningful effect on the reduction of the IFR and ISR. Also, no meaningful effect was found between IMS establishment and FSI and S.T.S. IMS establishment could reduce the IFR and ISR, which in turn may promote productivity indicators. Eventually, it could be concluded that IMS establishment can be used as an effective proceeding to improve workplace safety indices.

Ergonomic Design and Evaluation of an Electric Nail Removal Device

Sat, 22 Jan 2022 06:54:00 +0000

Nowadays, musculoskeletal disorders resulting from working with improper hand tools have been known as one of the major concerns in various industries. In the current study, an ergonomic nail removal device was proposed to evaluate the intervention for nail removal activity in the woodworking and carpentry industry. Eleven male workers, who were actively involved in nail removing activity, were asked to perform nailing activity by removing nails driven into the bottom and top of the door as the base points for painting the doors using both the nail removal device and the traditional plier. The Rapid Entire Body Assessment (REBA) and Strain Index (SI) techniques were used to characterize the level of risk. Moreover, nailing task duration and task repetition were measured as important criteria in manual works. According to the SI and REBA risk indices, the final scores for the designed device were estimated at 2 (low-risk level) and 1.5 (safe), respectively, while these values for the traditional pliers were 12 (high-risk level) and 15 (dangerous). Moreover, using the designed electric nail removal device led to a reduction in the repetition and duration of the task. Overall, the application of the proposed device in the nail removal tasks has shown risk indices below the critical thresholds in terms of correcting work posture and reducing strains imposed on workers' upper limbs.

Determining and Comparison of Sound Absorption Coefficients using Small Reverberation Chamber and Test Tube Methods

ALIREZA DEHDASHTI, ADEL MALEKMOHAMADI, GHOLAMREZA GHAEINI — Sat, 22 Jan 2022 07:06:36 +0000

Sound absorbing materials have been widely used to decrease hazardous noise in indoor and outdoor environments. In the present study, we designed and constructed an experimental laboratory-scale chamber to measure the sound absorption coefficients of porous materials in comparison with the measurements of the test tube method. The main reason was to design and construct a small chamber to enable testing of acoustic material samples in small dimensions allowing easy and rapid testing of acoustic materials. The acoustic chamber method was based on the formation of reverberation field of the acoustic waves across testing chamber locations, but differences in sound pressure throughout the chamber may result in measurement errors. Therefore, the chamber was constructed with a volume of 2.85 m3, wall reflectors, and a rotating sound source was designed to ensure a diffusive field. The tests were conducted with samples of 12.4m2 installed on interior surfaces of the chamber. Sound absorption coefficients of acoustic polyethylene and polyurethane absorbents were measured across the central frequencies of the octave band. Sound absorption coefficients under reverberant random incidence and normal incidence were related to the sound frequency. The chamber method predicted higher sound absorption coefficients compared to the coefficients obtained by the tube test method for all tested porous materials. Based on the results of the proposed small chamber, it can be concluded that sound absorption coefficients measurement of samples in an environment was more similar to real situations.

Demographic and Occupational Risk Factors of Carpal Tunnel Syndrome among Dental students in their Final Year at King Abdulaziz University, Jeddah, Saudi Arabia

Sat, 22 Jan 2022 07:10:25 +0000

Carpal tunnel syndrome (CTS) is a common peripheral compression neuropathy that accounts for 90% of all entrapment neuropathies. Dentists typically have a higher prevalence of work-related musculoskeletal disorders including CTS. Currently, there is a lack of literature on CTS prevalence and risk factors among dentistry in Saudi Arabia. Our study was the first to examine the prevalence and the associated demographic and occupational factors of CTS among dental students. This cross-sectional study was conducted in the School of Dentistry at King Abdulaziz University. A total of 120 dental students in their final year were included. We used a validated self-administered questionnaire that included demographic data, work, medical history, and a modified Katz's hand diagram to assess the symptoms and occupational exposures. Descriptive statistics and logistic regression were applied using SPSS software version 16. The prevalence of CTS among dental students was 13.3%. It was higher in females 10% compared to male 3.3%. There was a significant relationship between the body mass index (P= 0.03) with underweight category by having a higher prevalence of CTS. The use of finger pinch grip showed an inverse association with CTS (P=0.04). Other risk factors were not significantly associated with CTS. The prevalence of CTS among dental students was higher than the general population. However, many previously identified risk factors showed no significant association with CTS adding to the controversy of the contributing risk factors of this disease among dentistry. Finger pinch grip showed inverse association which was contrary to published literature. Future studies may include exposure time for each occupational risk factor preferably in a prospective cohort.

Psychometrics of Questionnaires Designed for the Evaluation of Safety Levels and Safety Culture Case Study: Power Plant Generator Manufacturing Company

Sat, 22 Jan 2022 07:15:00 +0000

The psychometrics of instruments in safety performance evaluation is essential for the accreditation of an organization’s safety evaluation and has been emphasized in many studies. Psychometrics pertains to the validity and reliability of an evaluation instrument and describes its precision and consistency. The aim of the present study was to evaluate the psychometrics of safety level and safety culture questionnaires to provide a reliable and valid instrument for safety performance evaluation in industries. This descriptive cross sectional study was conducted with the intention of psychometric instruments used to evaluate the safety level and the safety climate at the Mapna Pars power plant generator manufacturing and engineering company. The face validity of the questionnaires was analyzed quantitatively and qualitatively. In the quantitative method, the importance of the influence score was applied and the content validity was calculated using the Lawshe method. Content Validity Ratio (CVR) and Content Validity Index (CVI) were also used. For this purpose, elicitation was obtained from experts within the professional health and safety community. The reliability of the instruments was determined via the Cronbach's alpha test and the Interclass Correlation Coefficient (ICC) test. Finally, the standardized questionnaires were used to evaluate the safety level and safety climate of the industry as a case study. The obtained data were analyzed using SPSS software solution v20. Based on the quantitative face validity results obtained at the Mapna Pars Company, one question was removed from each of the final instruments. The content reliability analysis revealed that the safety level questionnaire had a CRI of 0.99, CVR of 0.91, and was accepted. The safety climate questionnaire had an acceptable CVI of 0.95 and an acceptable CVR of 0.82. Regarding the reliability analysis, a Cronbach's alpha of 0.72 and 0.89 was obtained for the safety level questionnaire and the safety climate questionnaire, respectively. It can be concluded that both questionnaires had an acceptable level of internal consistency. The re-application of the questionnaires after two weeks revealed a relatively consistent safety level (ICC=0.90) and safety climate (ICC=0.74). Analyzing the data obtained in the present study showed that the safety level questionnaire with 66 questions and the safety climate questionnaire with 93 questions had acceptable validity and reliability. Thus, it may provide a useful approach for safety evaluations in similar industries.

Limitations of WBGT Index for Application in Industries: A Systematic Review

Sat, 22 Jan 2022 07:19:28 +0000

The Wet Bulb Globe Temperature (WBGT) is still widely applied as a preliminary tool for evaluating heat stress. This index faces some limitations not considered yet. This systematic review was conducted aiming at highlighting some limitations for the development of the WBGT index. The present study was organized using more extensive databases, including PubMed, Google Scholar, Scientific Information Databases (SID), Elsevier, Web of Science, Scopus, Irandoc, Magiran, and Iran Medex. The used search terms were WBGT index, Heat stress, Thermal Stress, Heat strain, Wet Bulb Globe Temperature, Hot Condition, Occupational Health, and Occupational Exposure indices. In this study, 69 articles from the years 1950 to December 2021 were assessed. The WBGT index, despite having some advantages, suffers limitations that should be considered for a more accurate estimate of thermal stress. This study was pointed to the new limitations, including the value of WBGT is not clear for persons whose working in a seated posture. The additional problem with the use of this index was that it was used for adapted people who have consumed enough water and salt, while neither water nor salt is always readily available in most hot working environments. Therefore, using this index will cause an error. Also, in heterogeneous environments, if the heat source is near the head or legs, a coefficient will not be applied to these regions. The results of the study demonstrated that, because of the limitations of the WBGT index, it is recommended that this index be used along with other indicators and physiological parameters to assess heat stress until more extensive studies would be conducted in an attempt to improve and remove its limitations.

Application of Microextraction Methods to Extract and Determine the Occupational Analytes from Urine Samples: A Brief Review

ELNAZ TAHERI, FATEMEH DEHGHANI, NEGAR SAFARPOUR KHOTBESARA , NEMATULLAH KURD — Sat, 22 Jan 2022 07:25:07 +0000

Inexpensive and simple microextraction methods with high efficiency are highly recognized approaches for sample preparation in the analysis of pollutant compounds. Therefore, the present study was aimed to review the studies conducted by Iranian researchers on the use of microextraction methods to determine the occupational analytes from the urine sample. In the current review study, we used keywords, including microextraction, determine, extract, analytes, and urine samples among published articles by Iranian researchers from 2000 to 2019 in databases of Google Scholar, ISC, SID, Magiran, Web of Science, ScienceDirect, PubMed, and Scopus. Then, the extracted articles during the past 20 years were categorized and analyzed according to the title, author name, publication year, study method, study type, and evaluation results. The results of reviewing the selected articles were discussed in terms of several topics. They included optimization of affecting factors method efficiency and extraction efficiency, optimization of parameters affecting extraction performance, application of the optimized method for real samples, and comparison of the proposed method with other procedures. The developed methods in the selected articles were found to be fast, simple, with minimum solvent consumption, short extraction time, and environmentally friendly that can be used as alternatives to conventional methods.