Journal of Health and Safety at Work

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Introduction: Considering the necessity of evaluating novel thermal indices for different individual and environmental conditions, the aim of this study was validation of a new enthalpy index for evaluation of heat stress in hot and dry climate.

Material and Method: In this descriptive analytical 97 city services outdoor workers were randomly selected and evaluated in spring and summer seasons in Qom city, Iran. Correlation between new enthalpy index and standard WBGT index, as well as physiological response of deep body temperature was studied and analyzed.

Result: Findings showed that regardless of the time of measurements, correlation between enthalpy and WBGT index was better than its correlation with tympanic temperature (R2= 0.756 versus R2= 0.391). Considering the time of measurement, it was found that with increasing temperature and decreasing humidity, the correlation between indices was reduced, although the correlation ratio was maintained similar.

Conclusion: Due to the simplicity of the enthalpy index measurement ,its independency to measure the globe temperature and the possibility of estimation of this index using daily climate parameters in meteorological stations, and on the other hand, appropriate validity of enthalpy against WBGT and core temperature, it can be a good alternative for WBGT index and as a screening index for thermal environments in hot and dry condition.

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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: 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

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Introduction: Heat stress is a critical problem in hot industries, especially in incredibly hot climates. It can greatly impair the work process and put the health of workers at risk. This study aims to investigate the applicability of the WBGT index in determining the allowable working time in very hot weather conditions in one of the steel industries in Ahvaz.
Material and Methods: This study was conducted in different sectors of a steel industry in Ahwaz. The physiological parameters of sixty workers working in different parts of the industry were evaluated. Environmental variables and the Wet-Bulb globe temperature (WBGT) Index were also simultaneously measured during work shifts. The acceptable work time was calculated based on the reserve heart rate (RHR) and the WBGT index.
Results: The heat stress index among all occupational groups, based on the WBGT index, was incredibly high and surpassed the recommended level (P<0.05). The statistical test results also indicated a significant difference between the two indices in predicting the adequate work time at different work stations (P <0.05).
Conclusion: The current study results revealed that using the WBGT index for assessing and managing the risk of heat exposure in a hot climate may not have sufficient reliability and performance. Consequently, it is recommended to use optimal indices based on environmental and physiological assessments in a hot climate in order to monitor and control the heat stress associated with heat exposure. 

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Introduction: Recent evidence indicates that lighting can affect physiological and neurobehavioral human functions, referred to as non-image forming (NIF) effects of lighteffects. This study aimed to determine the effects of illumination levels and correlated color temperature (CCT) on alertness and performance under NIF conditions.
Material and Methods: In this study, 22 participants were exposed to light at various levels of illumination, including very low illuminance (<5 lux, control) and light conditions with correlated color temperatures (CCT) of 4000 K, 8000 K, and 12000 K at 300 and 500 lux. The data collection process included recording the power of brainwaves (alpha, alpha-theta, beta, and theta), sleepiness and mood scales, and cognitive performance tests for sustained attention, psychomotor vigilance task (PVT), working memory, and inhibitory capacity.
Results: The results indicated that 500 lux light conditions at correlated color temperatures of 8000 and 12000K significantly reduced normalized alpha, alpha-theta power, subjective sleepiness, and performance compared to the dim light condition. Under illumination levels of 300 and 500 lux, there were no significant differences in the measured values of the variables.
Conclusion: Lighting interventions can be used as a supplement to other strategies for increasing alertness and performance in the workplace.

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Introduction: Studies have demonstrated that teaching carries a substantial burden of health risks. Prevalent health issues among teachers include asthma, respiratory diseases, musculoskeletal problems, and mental disorders. These problems can be attributed to the specific attributes of their work environment. Consequently, this study aims to investigate the correlation between air quality within educational establishments and the overall health of teachers.
Material and Methods: This systematic review aims to examine the impact of temperature, humidity, and ventilation rates within educational environments on teachers’ health status and thermal comfort. Relevant studies were searched for using the PubMed and Web of Science databases, employing keywords such as teacher, temperature, humidity, ventilation, school, classroom, health symptoms, and thermal comfort (2000-2022). The inclusion criterion was that articles examined teachers’ health and comfort with temperature, relative humidity, and ventilation of the educational place.
Results: Out of the 103 articles found in the initial search, 13 articles were finally reviewed. Six studies investigated the voice abnormalities of teachers due to various factors (including temperature, relative humidity, and the ventilation rate of the educational place) and found that these abnormalities were affected by these factors. Two studies explored the relationship between the prevalence and exacerbation of respiratory symptoms and quality parameters of the indoor environment of educational places. Additionally, five studies investigated the relationship of air quality parameters of educational places with common non-specific symptoms among teachers.
Conclusion: Teachers frequently experience symptoms such as voice disorders, respiratory difficulties, allergies, and other nonspecific ailments, which may be associated with the quality parameters of the indoor environment in educational settings. These parameters include temperature, humidity, and ventilation rate. Consequently, controlling and regulating these parameters within the recommended values can help prevent the onset or exacerbation of these symptoms.