Journal of Health and Safety at Work

Introduction: Heat stress is considered as physical hazard, in working environments. The effects of working in hot environment include: muscle cramp, fatigue, loss of consciousness, perception and heat exhaustion.The purpose of this study was to evaluate heat stress and identify hazardous workstations in terms of heat stress in one of the Teheran's forging industries, using WBGT index.

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Methods and Materials: This Cross-Sectional study has been done in one of the forging industries of Tehran on five successive days during the warmest period in Summer 2010. for measurements, a calibrated WBGT meter according to ISO7243 standard was used. All workers who were exposed to radiant heat in this industry, had more than 3 years continuous work history, So they were well accommodated to the environment. For statistical analysis SPSS14 and Exell2007 software were used.

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Results: In this study, the WBGT of all workstations in the exposed to the furnace were estimated. the workstations average WBGTTWA were calculated 27.97°C, Which were higher than the threshold limit value according to ACGIH recommendation. The ANOVA and Post hoc(LSD) tests showed significant difference in the radiant heat (P-value<0.01), and WBGT index (Pvalue<0.05), between three different heights of the body. The observed differences between head and waist were not significant, but the difference between two heights and the ankle were significant.

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Conclusion: Heat stress in workers exposed to the radiant heat sources were higher than the Threshold limit value, which recommended by ACGIH. The results also indicated that the main problem were the radiant heat, especially in the head and waist height. Hence in order to decrease the radiant heat, some control solutions were Suggested.

Introduction: Heat stress in workplaces cause multiple problems such as thermal stresses, thermal discomfort and in more severe cases may lead to accidents and diseases related to excessive heat. The aim of this study was to evaluate heat stress adopting WBGT Index in some small enterprise in Qom city and also to examine the relationship between WBGT and physiological indices.

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Material and Method: This Cross-sectional study was conducted in 25 small workshops in Qom city including of 10 indoor and 15 outdoor workshops in August 2012. WBGT were measured according to the ISO7243 standard. The physiological responses including pulse rate, systolic and diastolic blood pressure were measured among 25 workers (one from each workshop).

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Result: The average WBGT index for indoor job were 27.55 Ċ among auto body repair, 27.45 Ċ in mechanics, 24.64 Ċ in painters, 26.73Ċ in welder and 25.89 Ċ in manufacturing doors and windows makers. For outdoor jobs as auto body repair, mechanics and painters it was 30.01 Ċ, and for welders and doors and windows makers 28.52 Ċ. Compared to the standard of ISO7243 WBGT all small workshops were higher than threshold limit. Auto body repair (30.22 Ċ) and painting (30.03 Ċ) workshops had highest WBGT. Average WBGT in auto body repair (as a job with most exposed to the open space and solar radiation) with welder and doors and windows, showed statistically significant differences T-test using WBGT with pulse rate, systolic and diastolic blood pressure did not have statistically significant (P>0.05). The findings indicated that workers are exposing to heat stress and doing more researches and representing preventive counter measures for the workers in this field are essential.

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Conclusion: Heat stress in almost all of the studied workplaces are higher than the recommended limits, and the outdoor workshops had the highest thermal stress, although heat stress did not show a significant correlation with the studied strains.

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.

Introduction: Outdoor workers are exposed to heat from solar radiation and the atmospheric conditions, in addition to the heat from the working process, which is worse by global warming. The purpose of this study was to evaluate heat stress based on wet bulb globe temperature index and also to examine the relationship between WBGT and physiological indices among outdoor workers of Shabestar city.

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Material and Methods: This cross-sectional study was conducted in August 2014. WBGT measurements were taken according to ISO7243 standard in different hours. The physiological response of 53outdoor workers (including heart rate, systolic and diastolic blood pressure, oral temperature, and skin temperature) were measured among9occupationalgroups, including municipal workers, concrete makers, porters, construction and road making workers, stonemasons, farmers, traffic officers, and street vendors.

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Result: The mean WBGT index for all outdoor workers, except for municipal workers, street vendors, traffic officers and stonemason, was greater than threshold limit. The highest average WBGT index was for construction workers and the lowest was for municipal workers (respectively 27 and 26 °C). Moreover, a significant direct association was reported between the WBGT index and physiological parameters (P <0.0001), with the highest correlation coefficient belonged to heart rate (r=0.492).

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Conclusion: According to WBGT index, porters, Concrete makers, construction and road makers, and farmers had the highest exposure at all times of the day while the lowest level was related to municipal workers. What is more, heat stress showed a significant correlation with the study strains. Therefore, it is essential to conduct further research and in order to represent preventive countermeasures for the workers in this field.

Introduction: Heat is one of the hazardous physical agents in the workplace. Exposure to heat and consequent thermal stress influence workers productivity in addition to adverse health effects. The aim of this study was to determine the heat stress induced productivity loss related to different tasks of farmers in Darreh Shahr city, during summer.

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Material and Method: This cross-sectional study was conducted in summer, 2014, among farmers in Darreh Shahr city. After determining the sample size, farmers’ activities were determined using hierarchical task analysis (HTA), and WBGT measurements were done according to the ISO7243. Metabolism was estimated by the ISO8996. Following, the type of activities were identified according their required metabolism. Knowing WBGT and workload and using the work capacity model, the productivity loss in different tasks and ultimately total productivity loss were calculated.

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Result: The mean WBGT activities for plowing, terracing, planting seeds, watering, fertilizing, weeding, spraying, and harvesting were 29.98 °C, 31.28 °C,30.66 °C,31.39 °C,31.99 °C,31.75 °C,31.08 °C, and 30.3 °C, respectively. WBGT values were higher than the permissible level provided by ISO7243 in all farming activities. Maximum value of WBGT was belonged to fertilizing activity (31.99 °C) and the lowest value was for plowing (29.98 °C). ANOVA test results did not show a significant difference in WBGT at head, waist, and ankle height. The highest and lowest amount of productivity loss was estimated respectively for weeding and plowing activities. The total productivity loss for farming was calculated 69.3 percent in an hour which is due to high physical activity, working outdoor, with exposure to direct solar radiation, and consequent heat stress imposed to workers.

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Conclusion: Productivity is a factor which is affected by the workplace heat stress. According to results of the present research, the amount of productivity is reduced in different tasks due to heat and this reduction is exacerbated by increase in temperature and might impact the local economy. Thus, further studies are needed to improve the working conditions.