Journal of Health and Safety at Work

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Introduction: Heat stress is considered as a serious risk factor to the health and safety of workers in most working environments, especially in outdoor works and jobs that workers are exposed to heat due to the working process. This study aimed to evaluate heat stress among workers of brick-manufacturing units in Qom city based on WBGT index as well as the relationship between WBGT and physiological indicators.
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Material and Method: The present study was conducted in 40 brick-manufacturing units in Qom city. WBGT measurements were performed according to ISO7243 standard. Physiological responses of 184 workers (up to 5 people per unit) and also atmospheric parameters were measured. The physiological responses included oral temperature, skin temperature, and temperature for the carotid artery of the ear, heart rate, systolic and diastolic blood pressure. Statistical analysis was done using SPSS software version 16.
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Result: Mean WBGT index for various brick-manufacturing jobs including firing, manual material handling, working with conveyors, molding, and tempering were 30.8 °C, 26.74 °C 26.58 °C and 24.25 °C, respectively and the average WBGT was estimated 27.98 °C. WBGT levels measured in all units exceeded the level provided in ISO7243 standard. The highest mean WBGT was belonged to kiln section (30.8 °C). The mean WBGT at three heights of head, abdomen and legs were not statistically different (using t-test). The correlation coefficients between mean WBGT and mean oral, skin and ears temperatures were 0.203, 0.319, and 0.490, respectively, with the highest correlation belonged to the carotid arteries of ears. Moreover, WBGT showed no significant association with the mean heart rate, systolic, and diastolic blood pressure (P-value>0.05). Indoor and outdoor WBGT index was significantly different (P-value<0.05).

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Conclusion: The level of heat stress in all brick-manufacturing units was higher than the recommended limits, and the workers in kiln unit were more exposed to heat stress, in comparison with other units. Therefore, special countermeasures should be adopted to control heat stress for this occupational group.

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Introduction: Traffic noise has been thought as a major environmental stress in modern societies, and the cause of physiological and psychological disorders according to the World Health Organization. Moreover, traffic noise can interfere with mental performance. However, there is little coherent evidence showing the effect of traffic noise on individuals’ performance. Hence, this paper aimed to address the role of traffic noise in participants’ mental performance considering the complexity of the activity.
 

Material and methods: Thirty-five master students studying in Tehran University of Medical Science were recruited for this study. Traffic noise was recorded by tape recorder and the traffic noise level was simultaneously measured by sound meter. Then, participants had been separately sitting in silent compared to traffic noise environment before they performed the tests including “S₃”-type Choice Reaction Time (CRT) test as a simple activity and “S1”-type Determine Test (DT) as a complex activity taken from “Vienna Test System” software package.
 

Results: The comparison between scores resulted from DT and CRT tests ,before and after exposure to traffic noise under simple activity conditions, showed that there was little increase in mean score of reaction time (P-value=0.47) and motor time (P-value=0.49), showing no statistically significant changes in these variables. On the contrary, following exposure to traffic noise, the DT test under complex activity condition revealed that there is a clear decreasing trend in median reaction time(P=0.001), number of stimuli (P=0.014) and number of reactions (p=0.009) in participants, and also, no significant differences were found in correct responses (P=0.091) and incorrect responses (P=0.073).
 

Conclusion: One of the most significant findings emerged from this study is that traffic noise seems to have no effect on the mentioned variables under simple activity condition. However, traffic noise has devastating effects on median reaction time, number of appeared stimuli and reactions under complex activity condition.

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Introduction: Nowadays, exposure to extremely low frequency (ELF) magnetic field has been interested in many studies due to possible effects on human physical-mental health. Therefore, this study aimed to assess arc welders’ exposure to extremely low frequency magnetic field and to determine its relationship with the secretion of paratormone (PTH) hormone and mood states.

Material and Method: The present study has been conducted among 35 healthy production workers (as exposed group) and 35 healthy administrative personnel (as unexposed group). After checking the work activities of participants according to the guide recommended by the National Institute for Occupational Safety and Health (NIOSH), ELF magnetic fields were measured using an ELF measurement device in the regions including trunk, head, and neck. The plasma levels of PTH hormone of both groups were evaluated by the Electrochemiluminescence method. Stress-Arousal Checklist (SACL) was used to assess the mode states of subjects in both groups. The collected data were analyzed by SPSS software version 16.

Result: There was a significant difference between the exposed and unexposed groups with respect to the exposure level to ELF magnetic fields (P-value<0.0001). Mean PTH hormone level in exposed group (34.54 pg/ml) was lower than unexposed ones (37 pg/ml), however these mean values weren’t significantly different (P-value=0.67). Score of “stress” subscale related to the “pleasure” and score of “arousal” subscale  related to the “activities and alertness” in the unexposed group were significantly higher than those in exposed group (p<0.0001). Regarding the relationship between exposure level to ELF electromagnetic field and scores of  stress, arousal, and PTH hormone level in the two groups, it should be stated that only a significant and positive association was found between the average exposure to ELF magnetic fields and PTH levels in the exposed group (P-value<0.009, r=0.44).

Conclusion: The results of this study showed that continuous welding can be considered as an exposure source to extremely low frequency electromagnetic fields. More accurate and comprehensive laboratory and field studies are needed to prove the hypothesis of the potential impact of extremely low frequency magnetic fields on people’s psychological states and mood through changes of parathyroid hormone level.

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Introduction: Carpal tunnel syndrome is followed by pushing Median nerve in the carpal tunnel of the wrist. Occupational factors such as repetitive movements of the hands and fingers and frequent wrist disturbances affect the development of this syndrome. Quality of life is a multidimensional concept including physical and mental performance. The aim of this study was to determine the prevalence of CTS and its impact on the quality of life of typists in Tehran.  
Material and Methods: This analytic descriptive cross sectional study was conducted in 1396 on 363 typists from 50 typing institutes in Tehran. Data were collected Demographic-Job Profile Questionnaire, Boston (BQ), quality of life (SF36) and Visual Analog Scale (VAS). Data were analyzed using SPSS-22 software and methods such as ANOVA and Pearson correlation tests.
Results: Among 363 participants, 215 of them were female (59.23%) and 148 were male (40.77%). The mean age was 37 ± 12.58 years. Among the typists, 51 (14.55%) had one-sided hand conflict, and 312 (85.95%) were two-sided hand conflicts. Results indicated that the prevalence of CTS symptoms among women was higher than that of men The value of Pearson correlation coefficient (range: 0.0613-0.783) showed that there was a moderate to strong correlation between the severity of symptoms scale (SSS), functional status scale (FSS) and visual analog scale (VAS) in the population under study (p< 0.05). There was also a strong and significant correlation between SSS and FSS among typists. In this study, CTS symptoms have a significant negative effect on the quality of life of the typists, but the psychological dimension quality of life is not to be affected by these symptoms.
Conclusion: Regarding the existence of CTS symptoms among typists who work most of a day with computers, there is also a statistically significant relationship between the incidence of CTS symptoms and the quality of life in this occupational group. Therefore, it is recommended that more attention should be paid to these individuals, appreciate tools be correctly designed, and further study be done.

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Introduction: Risk identification and investigation is an appropriate and practical approach for the occupational health professionals. This paper aims to determine exposure to the gases and metal fumes and to perform risk analysis in three common types of welding activities in a shipbuilding industry.
Material and method: This analytical cross-sectional study was conducted in a shipbuilding industry and three types of welding were considered including SMAW, MIG and MAG welding. Sampling of Mn and Cr fumes was carried out using NIOSH 7300 standard method, and NIOSH 6014 method NO2 sampling, and also direct reading devices for CO and O3 gases. Moreover, SQCRA risk assessment method was adopted to specify the level of exposure risk.
Results: The results of risk analysis showed that among gas pollutants, O3 and NO2 in all welding processes had a very high-risk level, while among the metal pollutants; Mn metal showed a high and very high risk level in MIG and SMAW welding.
Conclusion: According to the both sampling results and risk analysis, MIG process welders are more dangerous position than other types of welding.

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Introduction: Although noise characteristics such as intensity and frequency are the main cause of detrimental effects, it is important to pay attention to the personality traits of individuals as the host of adverse health effects. The aim of this study was to investigate the effect of personality traits on sensitivity, annoyance and loudness perception due to exposure to high frequency sound.
Material and method: This interventional and experimental study was carried out among 80 undergraduate and postgraduate students in 2017. First, examinee were exposed to a high frequency noise at 65 dBA for one hour in an acoustic room. Then, to determine amount of annoyance, sensitivity, loudness perception and to investigate personality traits, questionnaire of noise annoyance, noise sensitivity, loudness perception and Eysenck personality inventory was used, respectively. Finally, Chi-square, independent t-test and multivariate analysis of variance (MANOVA) were used to data analyze.
Results: The mean±SD of sensitivity, annoyance and loudness perception were 54.08±7.71, 7.0±1.53, and 2.79±1.13, respectively in this study. The mean scores of sensitivity, annoyance and loudness perception were significantly different in terms of personality traits, so that their average was higher in the neurotic and introverted. Based on MANOVA test results, personality traits had a significant effect on sensitivity, annoyance and loudness perception of individuals. In a way, the neuroticism and introversion had the greatest effect on the sensitivity and annoyance, respectively.
Conclusion: The results of this study showed that personality traits such as introversion and neuroticism can affect the sensitivity, annoyance and loudness perception of individuals.

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Introduction: Due to occupational accidents, many costs are annually lost from the countries’ Gross Domestic Product (GDP). Estimating these costs can be essential for optimal investments and establishing appropriate policies in many countries, such as Iran. The present study aimed to review the studies conducted on the safety economics and the costs of accidents in Iran from 2000 to 2021.
Material and Methods: The reliable databases “Web of Science”, “Embase”, “IranDoc”, “SID”, “Magiran”, “Google Scholar”, “PubMed” and “Scopus” were used to conduct this research. Articles in these databases were searched and extracted by searching for keywords such as “accident”, “cost of accidents”, “occupational accidents” and “Iran” in Persian and English from 2000 to 2021.
Results: Among the 66 identified articles, 19 were selected as final articles, of which 11 studies were carried out in the transportation industry and eight in other industries. Among these studies, nine studies only examined and stated the total costs, and six studies separately examined and stated the direct, indirect, and total costs. Four other studies also investigated and expressed the costs caused by accidents in other ways. Most notably, in three studies, the number of direct costs is higher than indirect costs. Similarly, only six studies estimated the damage to the GDP, ranging from 0.03% to 6.46% of the GDP.
Conclusion: The results of the review of studies showed that occupational accidents cause the loss of a significant part of Iran’s GDP. It is recommended to carry out further studies on the relationship between investment in the safety sector and reducing the costs of accidents concerning the grouping of jobs, mainly in the process, service, and production industries, to prevent wasting such heavy costs.

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Introduction: Failure Mode and Effects Analysis (FMEA) is a structured way to find and understand the states of a system’s failure and to calculate the resulting effects. In this method, which has been criticized by many researchers, the risk priority number is obtained for each failure mode based on the multiplication of the three parameters of occurrence (O), severity (S) and detection (D). In order to overcome the disadvantages of the traditional method of FMEA, such as ranking the failure and weighting the parameters, this research proposes a model in the fuzzy set.
Material and Methods: The model proposed in this paper is a nonlinear model for weighting the parameters of the FMEA and the revised TOPSIS method for ranking the failures, which is used for the first time to improve the FMEA method.
Results: The proposed model was presented in the Copper Complex of Shahr-e-Babak to assess safety risks. Based on the results of the study, it was found that in this proposed model, the weights of severity and detection were 0.479 and 0.186, respectively, and the results of the ranking showed that the risks of falling from height and getting stuck between objects had the highest and lowest priorities, respectively.
Conclusion: In the proposed model, based on Logarithmic Fuzzy Preference Programming and the revised TOPSIS method, the definite weights of the parameters were presented without any fuzzy number ranking and risk ranking with more criteria, respectively. Therefore, the proposed model has a higher ability compared to the traditional FMEA, and its application can be recommended to determine the ranking of risks.

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Introduction: Many general indicators have been proposed to assess an organization’s safety performance. However, due to their holistic nature, these indicators may not always reflect safety-specific aspects of an organization’s performance. In other words, the nature of an organization’s activities necessitates the use of specific criteria to better reflect safety performance. This study aimed to identify and measure key safety performance indicators using the Delphi method in Alborz Province Electric Power Distribution Company.
Material and Methods: This descriptive, survey-based study utilized the Delphi method to collect the opinions of 11 safety experts in the electric power distribution industry. Opinions were gathered in four phases, and key indicators were determined in the last phase of the study. These indicators were subsequently used to evaluate the safety performance of Alborz Electric Power Distribution Company for three months.
Results: This study identified and documented 34 safety activities. The expert group proposed 20 indicators in the first phase of the Delphi method. In the second and third phases, four and one indicators were eliminated, respectively, because they did not receive the required score. The content validity ratio (CVR) and content validity index (CVI) were calculated for the remaining 15 indices in the fourth phase. The results revealed that the mean quarterly performance scores of Alborz Province electric power distribution districts and departments in 2016, including Nazarabad, Savojbolagh, Mehrshahr, Fardis, West, East, Taleghan, and Eshtehard, were 78.9, 54.7, 78.8, 75.9, 75.7, 80.8, 61, and 83.5 out of 100 points, respectively.
Conclusion: The Delphi method is useful for identifying key safety performance indicators. The indicators discovered using this technique are active indicators (pre-accident) that are crucial in determining Alborz Electric Power Distribution Company’s safety performance. These indicators are suggested for use in evaluating the safety performance of other electric power distribution companies.

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Introduction: Lifting loads in awkward postures is a main cause of low back musculoskeletal disorders. In this context, researchers have used various indicators to determine the relationship between biomechanical variables and the risk of these disorders. This study aimed to investigate the correlation between plantar pressure distribution and the values of UTAH back-compressive forces (BCF) and lifting index (LI) during symmetrical load-lifting tasks.
Material and Methods: Thirteen healthy men, aged 25 to 35, took part in this study. The participants were instructed to symmetrically lift loads weighing 7.5 kg and 15 kg in 15 different postures, considering three horizontal distances (A, B, C) and five different heights (1-5). Pressure on the foot soles was recorded using 16 force-sensitive resistors (FSR) corresponding to eight anatomical areas on each foot. The BCF and LI were also calculated using the UTAH method and the NIOSH equation, respectively. Statistical analysis was performed using SPSS (version 21) software.
Results: Based on the results, when the load was closest to the body (A1-A5), the highest pressure was recorded in the heel and the 4th and 5th metatarsal of both feet. In lifting a load of 15 kg in the A2, B1, B2, C1, C2 postures and lifting a load of 7.5 kg in the C2 posture, the average BCF exceeded 700 pounds. The LI was greater than 1 for specific postures (B1, B2, B4, B5, C1-C5) at 15 kg and (C1, C2, C4, C5) at 7.5 kg load-lifting. During the 7.5 kg and 15 kg load-lifting, there was a significant correlation between the plantar pressure and the values of LI and UTAH (p-values < 0.05) in most postures.
Conclusion: The results showed a significant correlation between plantar pressure distribution and load-lifting postures. The study findings, which identify risk levels associated with lifting postures, lay the groundwork for future research aimed at categorizing safe and unsafe plantar pressure patterns.

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Introduction: The safety harness is a critical device for preventing falls from height, particularly in the construction industry. This study aimed to identify the factors contributing to the non-use of safety harnesses during work at height and to evaluate the comfort, satisfaction, and usability of these harnesses among construction workers in Tehran using a custom-designed tool.
Material and Methods: A semi-structured interview was conducted with construction workers to identify the factors influencing the non-use of safety harnesses. The collected data were analyzed using MAXQDA 10 software. Based on the results, which revealed dissatisfaction with the current safety harnesses, the levels of comfort, satisfaction, and usability were assessed using the Safety Harness Usability and Comfort Assessment Tool (SHUCAT) questionnaire.
Results: The reasons for not using safety harnesses were categorized into four main groups: management factors, worker attitudes, comfort, and harness design. These were further subdivided into 27 subgroups. The average satisfaction and comfort scores for safety harnesses were 26.8 ± 6.25, indicating that workers generally felt uncomfortable and dissatisfied with their harnesses. The average usability score was 38.70 ± 5.60, reflecting poor usability of the harnesses.
Conclusion: Improving the safety harness design could enhance workers’ comfort and satisfaction, increasing their willingness to use the equipment. Incorporating feedback from users and experts into the design process can help address the identified shortcomings and result in better product development.