Journal of Health and Safety at Work

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Introduction: Eye discomforts and headache are prevalent among computer users. The aim of present study was to determine eye discomforts and headache associated with computer use among dormitory students of Tehran University of Medical Sciences.

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Material and Method: In this cross – sectional study, data were collected using MIRTH (Musculo skeletal Injury Reduction Tools for Health and Safety) questionnaire. The results were Analyzed using SPSS Software and with descriptive statistical indexes as well as correlation test.

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Result: of the 744 distributed questionnaires, 631 students completed the questionnaire (84.4%). The mean age for the studied population was 22.72± 3.6 years. The relative frequency of eye discomforts for the female and male student was 76.38% and 70.11% respectively. The correlation test showed significant relationship between eye discomforts as well as headache with gender, work hours’ with a computer per day and glass use (P-V < 0.05). Also, the correlation between eye discomforts and headache was statistically significant (P-V < 0.01).

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Conclusion: Eye discomforts and headache relating to the computer uses are prevalent among students. The condition is more prevalent among females and prolonged computer users. Interventional and training programs should be considered to prevent and reduction of related problems.

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Introduction: Workers in open pit mines are frequently exposed to extreme heat stress during hot seasons. Several indices including Modified Discomfort Index (MDI) are used to evaluate the heat stress. The aim of this study was to evaluate the MDI and to investigate its relationship with ISO 7243 standard (Wet Bulb Globe Temperature index, WBGT) and physiological parameters of workers in an open pit mine.
 

Material and Method: This cross-sectional study was conducted among 120 healthy male miners in an open pit mine during summer season in 2014. Physiological parameters including body core and skin temperature, heart rate and blood pressure were measured according to ISO 9886 standard. All environmental and physiological parameters were simultaneously measured and recorded during a work shift. The MDI and WBGT indices were calculated using the related formula. Statistical analysis was performed using the SPSS 22 software.  
 

Result: According to the criteria of MDI, about 29 percent of workers had the average level, 68 percent of workers experienced the intense level and 2.5 percent suffered from the extreme level of exposure to the heat stress. No case of light level exposure to heat stress was obtained among workers. A significant correlation was found between MDI and ISO standard index (WBGT). Statistically significant correlation were also found between MDI and physiological parameters (P<0.001); in which the highest correlation coefficient was found for the heart rate variable (r=0.589).
 

Conclusion: Based on MDI, a high percentage of open pit mine workers were at risk of heat stress hazards. MDI had a moderate correlation with physiological parameters of the workers and showed a remarkable correlation with the WBGT.

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Introduction: Low back pain is one of the most common musculoskeletal disorders leading to disability around the world. Several studies have suggested that prolonged computer/ laptop work contributes to the development of low back pain and discomfort. The results of the studies conducted on the association of back discomfort and muscle activity are contradictory. Thus, the present study aims to evaluate the relationship between the activity level and relative rest time of the trunk muscles with back discomfort while working with a laptop in a sitting position.
Material and Methods: First, 20 young healthy males performed laptop work including mouse work and typing in conventional and ergonomic setups. In the ergonomic setup, the screen height and keyboard placement were specifically adjusted for each individual. In addition, the electromyographic activity of the lumbar erector spinae, right and left multifidus and transversus abdominis, rectus abdominis, external oblique muscles, and the posture of the lumbar spine were recorded in the first and last two minutes of an 8-min task. After the end of each task, the participants scored their back discomfort.
Results: The results showed a positive correlation (r=0.57 and p=0.009) between back discomfort and the EMG amplitude of the lumbar erector spinae muscle. In addition, back discomfort was negatively correlated to the relative rest time of the multifidus muscle (r=0.50 and p=0.023), and a positive correlation was reported with the relative rest time of the transversus and rectus abdominis (r=0.47, p=0.039, and r=0.45, p=0.049, respectively).
Conclusion: The relative rest time of the trunk muscles may be a better index than that of the EMG amplitude to highlight the risk factors for back discomfort. However, a causative link between muscle activity and discomfort cannot be implied from this study. The current results do not undermine the role of other factors associated with the increased level of discomfort during sitting.

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Introduction: The manufacturing, service professions, and other occupations commonly require their employees to spend more than 2 hours of their workday in an upright position which can potentially cause temporary or permanent health effects. The objective of this study is to determine the effect of anti-fatigue mats on leg muscle discomfort and muscle activity due to prolonged standing.
Material and Methods: A total of 100 workers were involved in the study. The control and experimental group stood for 2 hours in a controlled room with or without the anti-fatigue mat while sorting an assortment of mixed items.  Borg’s scale questionnaire and EMG signals were used to monitor the muscle discomfort and activity of the respondents.
Results: The discomfort ratings and muscle activity in the experimental group were always at lower levels compared to the control group, which meant there was a reduction in mean perceived exertion rating for the knees, calves, and feet, i.e., 1.8, 2.5 and 2.6, respectively. The results showed that there was a statistically significant (P < 0.001) difference in the Borg’s scale of discomfort ratings and leg muscle activity between both groups.
Conclusion: The anti-fatigue mat can have a positive effect in preventing muscle discomfort and reduce muscle activity among the respondents during prolonged standing.

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Introduction: Sugarcane is an important and strategic product in many countries, including Iran. While the introduction of mechanization, e.g., sugarcane harvesting machines, has significantly enhanced the production process, operators of these machines still face many ergonomic and safety challenges. 
Material and Methods: The present study investigated the ergonomic status of sugarcane harvester operators by examining some of their physiological and physical evaluations. Physiological evaluations included heart rate, oral temperature, and energy consumption of the operators, perceptual strain index, and physiological strain index. Physical evaluation included estimating the amount of pain and discomfort in body segments. The correlation between pain and discomfort of body parts with some demographic and physiological indices of users was investigated using IBM SPSS 24 software.
Results: Sugarcane harvester operators’ heart rate, energy consumption, and physiological strain index were 79.05 beats/min, 18.81 kJ/min, and 0.83, respectively. The average of three indices of thermal sensation, perceived exertion of activity, and perceptual strain index were estimated as 4.40, 9.21, and 8.86, respectively.
Conclusion: Pain and discomfort in the neck and back segments, like many agricultural activities, had the highest rate among the body parts. Also, shorter and thinner operators reported higher pain and discomfort in some segments of the body.