Journal of Health and Safety at Work

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Introduction: Control room is one of the most important working environments that require optimal performance of individuals to minimize errors. Lighting is one of the environmental factors affecting the operation of the control room operators. Providing optimal lighting in the control room is very important. The purpose of this study was to determine the effect of light on workload, sleepiness, eye fatigue, and satisfaction of individuals from light conditions.

Material and Method: This was an interventional study conducted in a control room of a power plant. Intervention in the control room lighting was performed with two lighting systems including fluorescent lamps (4000 Kelvin, 200 lux) and LED lamps (4,000 Kelvin, 400 lux). Sixteen operators were evaluated under the two lighting systems in terms of workload, sleepiness, eye fatigue and satisfaction of individuals from light conditions.

Result: According to the results, eye fatigue significantly decreased after intervention (p (0.004>. Also, the higher light intensity, significantly decreased the level of sleepiness (p <0.001). In the study of workload, the amount of mental workload (p <0.001) and effort (p <0.03) decreased significantly, after intervention and the increase in the intensity of light; but physical demand, temporal demand, performance and frustration had no significant difference with the results before intervention.

Conclusion: In general, a combination of fluorescent and LED lighting systems, with 400 lux intensity, can provide optimal functional and mental conditions for control room operators. The illumination intensity of 400 lux in terms of workload, sleepiness, eye fatigue and the degree of satisfaction of individuals from light conditions provides a much better environmental condition than 200 lux.

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Introduction: Workers in steel manufacturing companies are extensively exposed to the volatile organic compounds (VOCs). Considering the health effects of these compounds, the purpose of this study was to determine occupational exposure to the BTEX compounds and also evaluation of carcinogenic risk due to benzene and non- carcinogenic risk for BTEX compounds in a steel industry.

Material and Method: This cross-sectional study was conducted in the coke production unit of the steel making industry. After collecting personal samples from breathing zone of the workers and analyzing of the samples the levels of exposure to the BTEX were quantitatively determined using Gas chromatography equipped with Flame Ionization Detector (GC-FID), according to the NIOSH 1501 standard method. Then, cancer risk due to benzene and non-cancer risks from BTEX compounds were calculated using Monte-Carlo technique.

Result: The analysis of personal samples indicated that benzene concentration in energy and biochemistry and benzol refinement sections of the plant were higher than occupational exposure limits (OELs). Among the studied sections, benzol refinement as the most polluted section had the highest concentration of BTEX compounds. Non-cancer risk due to BTEX compounds in all studied sections was lower than one. Benzene cancer risk in energy and biochemistry, benzol refinement and experimental furnace sections was higher than maximum recommended value by EPA.

Conclusion: Due to the high concentration of benzene in energy and biochemistry and benzene refinement sections as well as the resultant carcinogenic risk, improvement of existing control systems and the use of modern engineering systems are necessary to control occupational exposure.

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Introduction: This study was designed with the main purpose of examining the compatibility of the two indicators of wet bulb globe temperature (WBGT) and predicted thermal strain (PHS) in assessing the environmental conditions and the heat load imposed on the subjects.
Method: In this cross-sectional study, 163 bakers were included in the study. Thermal stress was determined using the WBGT and PHS. At the same time, physiological responses of subjects were recorded, including tympanic temperature, heart rate and mean skin temperature. Finally, the predicted heat strain was evaluated and compared with actual values.
Results: Based on the results, the WBGT index is accompanied with an underestimation and PHS with  an overestimation, compared to the tympanic temperature. In addition, the WBGT index with the core temperature and the predicted rectal temperature component of the PHS index are the most consistent (kappa value of 0.614 and 0.66, respectively). While the Kappa value is between the amount of water lost and the WBGT index, it indicates a mismatch (Kappa = 0.339).
Conclusion: The prediction of heat strains only based on the PHS index cannot reflect the actual heat load on individuals in thermal environments such as bakeries and it is associated with an overestimation. On the other words, this indicator is more suitable for indoor thermal environments, with minimal variation in individual and environmental factors affecting thermal stress