A method for rapid assessment of visual ergonomics and lighting conditions (RAVEL): An in-depth development and psychometrics study.

BACKGROUND: In workplaces heavily reliant on visual tasks, various factors can significantly influence an individual's performance, necessitating the use of reliable tools to identify and mitigate these factors. OBJECTIVE: This study aimed to develop a swift assessment method for visual ergonomics and lighting conditions, evaluating its validity in real-world scenarios. METHODS: The questionnaire's content validity was determined by a panel of experts using the content validity ratio (CVR) and content validity index (CVI). Construct validity was assessed through exploratory factor analysis (EFA), confirmatory factor analysis (CFA), and latent class analysis (LCA). Internal consistency was measured using Cronbach's alpha coefficient. The RAVEL index, derived from the calculated effect coefficients of items, classified total scores through receiver operator curves (ROCs). RESULTS: The rapid assessment method, comprising two parts with 30 items, demonstrated acceptable reliability with CVR, CVI, and Cronbach's alpha coefficient (α) at 0.75, 0.87, and 0.896, respectively. The EFA on the first part's 22 items identified three factors, confirmed by CFA. The LCA on the second part's eight items revealed that a two-class model best fit the data, with Bayesian information criterion (BIC) = 24249, 17, Akaik information criterion (AIC) = 2179.89, and an entropy R-squared of 0.83, indicating appropriate subject classification based on the model. The RAVEL score was categorized into three levels, with optimal cut points of 55 and 63. CONCLUSIONS: In conclusion, the study demonstrated that this method based on visual ergonomics serves as a rapid and reliable tool for assessing visual ergonomic risks of display users in the workplace.

Objective and subjective evaluation of the use of protective clothing on the thermal strain and mental workload of nurses during the Covid-19 pandemic.

BACKGROUND: Nurses are among high-risk occupational groups during the outbreak of epidemics. Therefore, these people are required to use personal protective equipment (PPE). Previous studies have shown that the use of personal protective equipment can affect people's thermal strain and mental workload. OBJECTIVE: The present study was conducted with the aim of objectively and subjectively evaluating the use of protective clothing on the thermal strain and mental workload of nurses during the covid-19 pandemic. METHODS: This cross-sectional study was divided into two groups with a sample size of 300 people who were selected by systematic random method. In the first group, 120 people were objectively evaluated (use of protective clothing). In the second group, 180 people only completed the questionnaire of mental workload, feeling of heat and sweating and other information related to the type of clothing and the duration of its use, etc. Measurements were done in August and September of 2021 and in the morning shift of hospitals. Data were analyzed using SPSS version 21 software and chi-square, independent T-test and linear regression tests. RESULTS: The average age and average working hours per month of the participants in the study were 33.51±7.88 years, 187.91±35.37 hours, respectively. The results showed that the predicted average vote (PMV) index and the predicted percentage of dissatisfied (PPD), moisture felt on the skin surface, the feeling of desirability and pleasantness of the temperature, the weight of sweat and the humidity inside the clothes between the two groups of people using insulated clothes There is a significant difference between medicine and dressing (P < 0.05). There was a significant relationship between mental workload and type of clothing, average working hours per month. CONCLUSIONS: The use of medical isolation clothes causes a high heat load on nurses and can increase their mental workload. On the other hand, people using normal gowns suffer from a high mental workload due to the fear of disease due to the uncertainty of high-level protection. In addition, medical isolation clothes increase the humidity of the skin due to their impermeability, which causes skin complications.

Climate Change and Occupational Heat Strain Among Women Workers: A Systematic Review.

Climate change increases heat stress exposure and occupational heat strain in tropical and subtropical regions with generally hot-humid climate conditions. The present systematic review was conducted to assess the effect of climate change on occupational heat strain among women workers. In this study, three main databases (PubMed, Scopus, and Web of Science) were searched to find relevant literature on climate change and its effects using subject headings and appropriate MeSh terms. This article has been written according to the PRISMA checklist. A total of 6,176 studies were identified for screening and 13 studies were eligible for data extraction. Scientific evidence reveals that there is an imprecise but positive relationship between climate change and occupational heat strain regarding women workers. Some complications associated with occupational heat strain among women workers include fatigue, discomfort, dehydration, reduced brain function, and loss of concentration. Climate change can lead to an increase in the occurrence of heat-related illnesses and the levels of injury risk. In addition, its adverse health effects on women workers are mentioned. This systematic study identifies key priorities for action to better characterize and understand how occupational heat strain among women workers may be associated with climate change events. Strong evidence indicates that climate change will continue to cause occupational heat strain among women workers. It is essential to implement preventive measures considering multidisciplinary strategies to reduce the adverse effects of climate change on women workers health in hot weather settings. This can limit the health risks and negative effects of climate change.

A novel framework for human factors analysis and classification system for medical errors (HFACS-MES)-A Delphi study and causality analysis.

The healthcare system (HCS) is one of the most crucial and essential systems for humanity. Currently, supplying the patients' safety and preventing the medical adverse events (MAEs) in HCS is a global issue. Human and organizational factors (HOFs) are the primary causes of MAEs. However, there are limited analytical methods to investigate the role of these factors in medical errors (MEs). The aim of present study was to introduce a new and applicable framework for the causation of MAEs based on the original HFACS. In this descriptive-analytical study, HOFs related to MEs were initially extracted through a comprehensive literature review. Subsequently, a Delphi study was employed to develop a new human factors analysis and classification system for medical errors (HFACS-MEs) framework. To validate this framework in the causation and analysis of MEs, 180 MAEs were analyzed by using HFACS-MEs. The results showed that the new HFACS-MEs model comprised 5 causal levels and 25 causal categories. The most significant changes in HFACS-MEs compared to the original HFACS included adding a fifth causal level, named "extra-organizational issues", adding the causal categories "management of change" (MOC) and "patient safety culture" (PSC) to fourth causal level", adding "patient-related factors (PRF)" and "task elements" to second causal level and finally, appending "situational violations" to first causal level. Causality analyses among categories in the HFACS-MEs framework showed that the new added causal level (extra-organizational issues) have statistically significant relationships with causal factors of lower levels (Φc≤0.41, p-value≤0.038). Other new causal category including MOC, PSC, PRF and situational violations significantly influenced by the causal categories of higher levels and had an statistically significant effect on the lower-level causal categories (Φc>0.2, p-value<0.05). The framework developed in this study serves as a valuable tool in identifying the causes and causal pathways of MAEs, facilitating a comprehensive analysis of the human factors that significantly impact patient safety within HCS.

Validity of ten analytical heat stress indices in predicting the physiological parameters of people under various occupational and meteorological conditions.

Until now, only a few comprehensive studies have validated analytical heat stress indices in different conditions. The present study aims to investigate the validity of these indicators in predicting the physiological parameters of workers. This cross-sectional study was conducted with 194 male employees working in warm environments. First, demographic information was collected. After participants rested for 30 min, their heart rate and tympanic temperature were measured. The subjects then performed their routine tasks. At the end of 90 min, their heart rate and tympanic temperature were again measured. Additionally, their metabolism rate and clothing thermal insulation were estimated. Environmental parameters were also measured at 30-, 60-, and 90-min time points. Additional information required to compute the indices was recorded. Then, the values of each of the indices were computed. Finally, the validity of the indices was assessed under different conditions. The results indicated that the highest regression coefficients with tympanic temperature were assigned to modified physiologically equivalent temperature (mPET) (0.7515), predicted heat strain (PHS) (0.7201), and predicted mean vote (PMV) (0.7082), index, respectively. Also, the greatest regression coefficients with heart rate belonged to mPET (0.7773), PMV (0.7624), and PHS (0.6479) index, respectively. Based on the results, the highest diagnostic accuracies of receiver operating characteristic (ROC) curves for tympanic temperature were related to indices of mPET, PHS, and PMV with the area under the ROC curve (AUC) of 0.945, 0.931, and 0.930, respectively. Of the studied indices, it was observed that mPET, PHS, PMV, and PPD showed more validity compared to others.

Design and Validation of Novel Evaporative Local Cooling Coatings to Prevent Adverse Health Effects of Heat Exposure.

Background: This study aimed to design and evaluate the cooling power of local cooling coats for the head, neck, ankles, and wrists. Methods: Local cooling coatings were designed using Iranians workers' existing 50th anthropometric percentile data. After immersing the cooling coats in water for 5 minutes, they were placed in a chamber at 30°C, 35°C, and 40°C and 30% and 60% humidity and 0.2-0.4 m/s air velocity for 120 minutes. The amount of water evaporation was measured by weighing each coat before and after entering the chamber, and then the cooling power of each coat was calculated based on the amount of water evaporation. Results: The average cooling power of cooling coats with covering areas (two wrists 933.75 cm2, two ankles 1467.37 cm2 and head and neck 1270 cm2) that the total area of the cover is 3671.12 cm2, i.e., about 20% of the body at 30% relative humidity in 30°C, 35°C and 40°C was 67, 77 and 89 watts, respectively. At the mentioned temperature and in 60% relative humidity, the cooling power was 34, 40, and 55 watts. As the relative humidity increased, the cooling power of the coats decreased. Conclusions: Local evaporative cooling coat on the head, neck, wrists, and ankles can reasonably repel excess heat entering the body. The best performance of these coats is in hot and dry environments. Probably, if used in conjunction with cooling vests in environments with high temperatures and heavy activity, it can act as a supplement to cooling vests and have a significant effect on improving functions.

Effect of air blowing inside isolated hospital clothing on perceptual and physiological heat strain in laboratory conditions.

Heat stress is one of the most common complaints of health care employees who wear isolation gowns to protect themselves from biological agents, particularly during the warmer seasons. This study was conducted in a climatic chamber to determine the influence of airflow within isolated hospital gowns on physiological-perceptual heat strain indices. The experiment was conducted in three trials: regular clothes (CON), an impenetrable gown without air blowing (GO), and a gown with air blowing (GO + FAN) at temperature conditions of 27 °C and 25% relative humidity (RH). During the trial, physiological-perceptual response data were recorded for a half-hour on a treadmill at a speed of km/hr and a slope of 0% activity at 5-min intervals. The ASHRAE Likert scale was used to assess thermal comfort (TC), thermal sensation (TS), and skin wetness sensation (WS). As the results show, there was a significant difference in mean scores for TC and WS in both sexes when working in the CON, GO, and GO + FAN groups (P < 0.001). In women, the mean scores for TS, TC, and WS reduced considerably (P < 0.001) in the GO and GO + FAN in the amount of 10 and 12 CFM (20 [Formula: see text]/h), but in males, there was a statistically significant difference between mean scores (P < 0.001) in the GO + FAN at 12 CFM (20 [Formula: see text]/h) and 14 CFM (24 [Formula: see text]/h). Also, the greatest difference between the average heart rate, chest temperature, and temperature inside the clothes in women and men in the trials GO and GO + FAN was observed in the air flow 12 CFM and 14 CFM, respectively (P < 0.001). The usage of an air blower in isolated hospital clothes has been shown to influence physiological-perceptual parameters in men and women substantially. The existence of airflow in these gowns can improve safety, performance, and thermal comfort while also decreasing the risk of heat-related disorders.

Application of "Human Factor Analysis and Classification System" (HFACS) Model to the Prevention of Medical Errors and Adverse Events: A Systematic Review.

Hospitals, as one of most important subsectors in human societies, are responsible for providing safe and effective medical services to clients. But sometimes these hospitals are the source of injury and death in patients by creating medical errors. In this systematic review study, the application of human factor analysis and classification system (HFACS) method in the classification of medical errors was investigated. Major electronic databases including Scopus, Web of Science, and MEDLINE were searched. All studies that investigated the application of HFACS method for coding, causation, and classification of medical errors and adverse events conducted from 2001 until February 2021 were included. A total of 108 articles were found. Due to duplication, 18 studies were removed from the review list. After reading the titles and abstracts, 50 of these publications were excluded because they had objectives different from this review. The remaining 40 publications were retrieved for further assessment. Of these, 28 publications were excluded because it did not meet the inclusion criteria. Finally, 12 articles remained for the final systematic review. We found that in 65% of the selected studies, preconditions for unsafe acts have been the major causal level of medical errors and adverse events. In the majority of the studies, communication and coordination, adverse mental states, physical environment, crew resource management, and technological environment have also been recognized as the most important causal categories in this study. As a result, to prevent medical errors and adverse events, the main focus should be on controlling the preconditions for unsafe acts including personnel factors, operator conditions, and environmental factors.

Assessing the students' readiness for E-Learning during the Covid-19 pandemic: A case study.

The aim of this study was to scrutinize the E-learning readiness among the students of the Faculty of Health at Isfahan University of Medical Sciences during the Covid-19 pandemic. This study was conducted as a descriptive-analytic study on 165 the students of the Faculty of Health in Isfahan University of Medical Sciences in 2021. To examine the level of the participants' readiness for E-learning during the Covid-19 pandemic period, the questionnaire developed by Watkins et al, was administered. Finally, the data analysis was performed with SPSS24 software. The results showed that the mean and standard deviation were 97.44 and 17.67, respectively. Only 1.2% of the participants had a low level of E-learning readiness. 27.9% were at the intermediate level and 70.9% were at the high level. Moreover, the results revealed that the participants had the highest degree of readiness in "Technology Access" and "Internet discussions" dimensions (0.79) and the lowest degree of readiness in "motivation" dimension (0.67). The results of this study indicated that the majority of the participants in this study had a high E-learning readiness, so the university can implement the virtual education. However, the students' learning motivation should be enhanced through providing the required infrastructure and holding training courses for the students specially the BA ones.

The effect of cooling vests on physiological and perceptual responses: a systematic review.

Humans in hot environments are exposed to health risks and thermal discomfort which seriously affect their physical, physiological and mental workload. This study aimed to assess the effects of using cooling vests (CVs) on physiological and perceptual responses in the workplace. Three main databases were searched using subject headings and appropriate Mesh terms. The article has been written according to the preferred reporting items for systematic reviews checklist. A total of 23,837 studies were identified for screening and 63 studies were eligible for data extraction. A statistically significant difference was observed in body temperature among hybrid cooling garments (HBCGs), phase-change materials (PCMs) and air-cooled garments (ACGs) at 31.56-37 °C (60% relative humidity), evaporative cooling garments at 25.8-28.1 °C and liquid cooling garments at 35 °C (49% relative humidity) compared to without CVs (p < 0.001). HBCGs (PCMs and ACGs) are effective means in hot, moderate, humid or dry environments.

Development of an observational - perceptual heat strain risk assessment (OPHSRA) index and its validation.

BACKGROUND: The thermal strain can be measured using subjective methods without the use of sensitive equipment. The purpose of the present study was the development and validation of an observational - perceptual heat strain risk assessment (OPHSRA) method. METHODS: This cross-sectional study, in 2019, was performed. At first, an observational-perceptual questionnaire was designed using effective items in producing heat strain. Then, the reliability and validity of the questionnaire were examined. Later, 201 male workers were asked to perform the routine tasks for 90 min under various climatic conditions after resting in a cool room. At the end of the activity, the tympanic temperature of the subjects was accurately measured. Also, the designed questionnaire was completed by researchers and participants. Then, the effect coefficients of the items were calculated and used for developing the novel index. At final, the index validity was investigated. RESULTS: The values of the content validity ratio (CVR), content validity index (CVI), and Cronbach's coefficient alpha (α) of the designed questionnaire with 16 questions were equal to 0.793, 0.913, and 0.910, respectively. The results indicated that environmental, job, administrative, and clothing items assessed by the questionnaire with the coefficients of 0.860, 0.658, 0.783, and 0.566 had significant effects on the thermal strain, respectively. These coefficients were exploited to develop the index. The result revealed that the OPHSRA index justified 69% of the variations of the tympanic temperature (R2 = 0.69). CONCLUSION: The novel index developed by the questionnaire had an acceptable validity. Therefore, this index can be used for estimating the risk of thermal strain in a variety of thermal conditions.

Identification, Classification, and Prioritization of Effective Factors in Producing Thermal Strain in Men at Workplaces using Fuzzy AHP Technique.

BACKGROUND: Various factors can affect thermal strain at workplaces. To prevent heat illnesses due to the heat strain, one must identify and prioritize these factors. Therefore, the present study was aimed to determine the relative importance of the effective factors in producing thermal strain in men at workplaces using fuzzy AHP technique. MATERIALS AND METHODS: This qualitative practical study was performed in 2019. Effective factors in producing heat strain were identified by a literature review. Then, an expert panel reviewed the identified factors and omitted some of them. Further, the balance theory of job design was applied to classify the heat strain factors. Later, these factors were categorized into six groups, including environmental, personal, job, clothing, administrative, and lifestyle elements. In the end, the fuzzy analytical hierarchy technique was used for prioritizing the elements and factors involved in each of them. RESULTS: Based on the results, the environmental element had the highest relative weight and priority (0.178). Other priorities were assigned to the job element (0.171), clothing element (0.171), personal element (0.169), administrative element (0.169), and lifestyle element (0.142), respectively. CONCLUSION: In general, the results showed that environmental factors are the most effective ones in producing heat strain. The results of the present study can be helpful in controlling the thermal strain.

Development and validation of an environmental heat strain risk assessment (EHSRA) index using structural equation modeling based on empirical relations.

BACKGROUND: Need to a simple, available, accurate, comprehensive, and valid indicator is felt to assess thermal effects. Therefore, the present study was aimed to develop and validate the environmental heat strain risk assessment (EHSRA) index using structural equation modeling (SEM) based on empirical relations. METHODS: This cross-sectional study was performed on 201 male workers in environments with various climatic conditions. The heart rate and tympanic temperature of the individuals were monitored at times of 30, 60, and 90 min after beginning the work. At these times, values of dry temperature, wet temperature, globe temperature, and air velocity were also measured and metabolism rate and clothing thermal insulation value were estimated. At the end, a theoretical model was depicted in AMOS software and obtained coefficients were applied to develop a novel index. The scores of this indicator were categorized into four risk levels via ROC curves and validate using linear regression analysis. RESULTS: Indirect effect coefficients of the globe temperature, dry temperature, wet temperature, air velocity, metabolism, and clothing thermal insulation variables on the tympanic temperature were computed by 0.77, 0.75, 0.69, 0.24, 0.49, and 0.39, respectively. These coefficients were applied to develop the index. Optimal cut-off points of boundaries between risk levels included 12.02, 15.88, and 17.56. The results showed that the EHSRA index justified 75% of the variations of the tympanic temperature (R2 = 0.75). CONCLUSIONS: The novel index possesses appropriate validity. It was suggested that this indicator is applied and validated in various environments in the next studies.

Development of a personal heat strain risk assessment (PHSRA) index in workplaces and its validation.

BACKGROUND: There is not a comprehensive heat stress index to screen the people susceptible to heat disorders and illnesses in hot workplaces. The present study was aimed to develop a personal heat strain risk assessment (PHSRA) index in workplaces and validate it. METHODS: This cross-sectional study was carried out on 201 Iranian male employees under various thermal conditions. At first, the demographical data of participants were gathered. After that, the heart rate and tympanic temperature of the subjects were carefully measured at times of 30, 60, and 90 min of starting the work. Environmental factors were measured simultaneously. The metabolism rate and insulation value of clothes were also estimated. At the end, a novel index of the heat strain was developed using structural equation modeling in AMOS and validated using linear regression analysis in SPSS. RESULTS: Indirect effect coefficients of personal factors including age, body mass index, maximum aerobic capacity, and body surface area were equal to 0.031, 0.145, - 0.064, and 0.106, respectively. The coefficients of main factors including dry temperature, wet temperature, globe temperature, wind speed, metabolism, and clothing thermal insulation were obtained as 0.739, 0.688, 0.765, 0.245, 0.482, and 0.383, respectively. These coefficients and normalized values of the factors were used to develop a novel index. The total score of the index was categorized into four levels by optimal cut-off points of 12.93, 16.48, and 18.87. Based on the results of regression analysis, this index justifies 77% of the tympanic temperature as a dependent variable (R2 = 0.77). CONCLUSIONS: In general, the results indicated that the novel index developed by the personal and main factors had proper validity in the prediction of thermal strain.

Comparison of the Impact of an Optimized Ice Cooling Vest and a Paraffin Cooling Vest on Physiological and Perceptual Strain.

BACKGROUND: Ice cooling vests can cause tissue damage and have no flexibility. Therefore, these two undesirable properties of ice cooling vest were optimized, and the present study was aimed to compare the impact of the optimized ice cooling vest and a commercial paraffin cooling vest on physiological and perceptual strain under controlled conditions. METHODS: For optimizing, hydrogel was used to increase the flexibility and a layer of the ethylene vinyl acetate foam was placed into the inside layer of packs to prevent tissue damage. Then, 15 men with an optimized ice cooling vest, with a commercial paraffin cooling vest, and without a cooling vest performed tests including exercise on a treadmill (speed of 2.8 km/hr and slope of %0) under hot (40°C) and dry (40 %) condition for 60 min. The physiological strain index and skin temperature were measured every 5 and 15 minutes, respectively. The heat strain score index and perceptual strain index were also assessed every 15 minutes. RESULTS: The mean values of the physiological and perceptual indices differed significantly between exercise with and without cooling vests (P < 0.05). However, the difference of the mean values of the indices except the value of the skin temperature during the exercises with the commercial paraffin cooling vest and the optimized ice cooling vest was not significant (P > 0.05). CONCLUSIONS: The optimized ice cooling vest was as effective as the commercial paraffin cooling vest to control the thermal strain. However, ice has a greater latent heat and less production cost.

Evaluating combined effect of noise and heat on blood pressure changes among males in climatic chamber.

INTRODUCTION: Exposure to noise and heat causes individuals to experience some changes in the function of cardiovascular system in workplaces. This study aimed to find the combined effect of heat and noise on systolic and diastolic types of blood pressure in experimentally controlled conditions. METHODS: This quasi-experimental study was performed with 12 male students in a climatic chamber in 2014. Blood pressure including systolic and diastolic was measured in the following conditions: 15 min after rest in exposure to heat (40°C, relative humidity [RH]: 30%), exposure to noise with 75, 85, and 95 dB rates in thermal comfort condition (22.1 ± 0.9 wet-bulb globe temperature), and combined exposure to heat (40°C, RH: 30%) and noise with 75, 85, and 95 dB. Friedman test was used to analyze the data. RESULTS: The mean change of systolic blood pressure was different significantly before and after exposure to heat and noise levels including 75, 85, and 95 dB (P = 0.015, P = 0.001, P > 0.001, P = 0.027, respectively). Although systolic and diastolic blood pressures changed drastically, it was not significantly different in simultaneous exposure to heat and noise. CONCLUSION: Both systolic and diastolic blood pressures decreased in exposure to heat, while exposure to different levels of noise elevates systolic and diastolic blood pressures. However, when exposed to a combination of heat and noise, subtle changes of blood pressure were traced, which can be characterized as average, considering heat-only and noise-only tension situations.

Performance evaluation of Iranian cooling vest on the physiological indices in hot climatic chamber.

BACKGROUND: Heat stress is a threat to those who work in high temperatures. The purpose in this study was an examination of the cooling ability of Iranian phase change material (PCM) cold vest in hot and dry conditions in a climatic chamber. MATERIALS AND METHODS: This experimental study was implemented on 12 male students (age 23.7 ± 2.8 years, weight 66.1 ± 11.4 kg, and VO2 max 2.53 L/min) in 2013. The heat strain score index (HSSI), skin temperature and oral temperature, and heartbeat in two phases with and without cooling vest was measured during 30 min in a climatic chamber (temperature 38.8 ± 1.3°C humidity ratio 32.9 ± 2.3%) and in two activity intensity of 2.4 and 4.8 km/h speed on the treadmill, and the data differences between groups "with" and "without" vest were tested by t-test and repeated measurement. The level of significance was considered as 0.05. RESULTS: The change in heartbeat at two activities, the oral temperature and heat strain score at 4.8 km/h, did not differ significantly between groups (with and without vest), as expected (P > 0.05). However, the change in skin temperature at two activities, oral temperature and heat strain score at 2.4 km/h, was significant between groups, as expected (P < 0.05). The average of skin temperature at 15(th) and 30(th) min during the experiment at two activities of 2.4 and 4.8 km/h was significant. CONCLUSION: The findings of the study indicated that using the Iranian PCM cold vest in hot and dry climate can affect the reduction of skin temperature, oral temperature, and HSSI in light activities.

Designing of the Cooling Vest from Paraffin Compounds and Evaluation of its Impact Under Laboratory Hot Conditions.

BACKGROUND: The phase change materials (PCMs) have the appropriate properties for controlling heat strain. One of the well-known PCMs is paraffin. This study aimed to design the cooling vest from the cheap commercial paraffin compound and evaluation of its effectiveness under laboratory hot conditions. METHODS: the cooling vest was made of the polyester fabric and it had 17 aluminum packs. The each of aluminum packs was filled by 135 g of prepared paraffin with a proper melting point in the range of 15-35°C. an experimental study was conducted on ten male students under warm conditions (air temperature = 40°C, relative humidity = 40%) in a climatic chamber. Each participant was tested without cooling vest and with cooling in two activities rate on treadmill to include: light (2.8 km/h) and moderate (4.8 km/h). The time of this test was 30 min in each stage. During the test, the heart rate, the oral temperature, the skin temperature were measured every 4 min. Finally, data were analyzed using the Kolmogrov-Smirnov and repeated measurement ANOVA test in SPSS 16. RESULTS: The latent heat of the prepared paraffin compound and the peak of the melting point were 108 kJ/kg and 30°C, respectively. The mean and standard deviation of heart rate, oral temperature, and skin temperature with cooling vest in light activity were 103.9 (12.12) beat/min, 36.77 (0.32)°C, and 31.01 (1.96)°C and in moderate activity were 109.5 (12.57) beat/min, 36.79 (0.20)°C, and 29.69 (2.23)°C, respectively. There is a significant difference between parameters with a cooling vest and without cooling (P < 0.05). CONCLUSIONS: The designed cooling vest with low cost can be used to prevent thermal strain and to increase the physiological stability against the heat. However, the latent heat of this cooling vest was low.

Validation of Perceptual Strain Index to Evaluate the Thermal Strain in Experimental Hot Conditions.

BACKGROUND: The incidence of heat stress is one of the most common problems in workplaces and industries. Many heat stress indices have been developed, and these indices have some disadvantages. The purpose of this study is to validate the perceptual strain index (PeSI) in experimental hot conditions. METHODS: This study is of cross-sectional carried out on 15 men at five different thermal conditions (35°C, 30°C, 27°C, 24°C, and 21°C) in a climate chamber and on a treadmill at three levels of light (2.4 kph), medium (4.8 kph) and heavy activity (6.3 kph). Heart rate and oral temperature were respectively measured to calculate the physiological strain index. Also, thermal sensation and rate perceive exertion were respectively measured to calculate the PeSI. Finally, the correlation between the indices was analyzed using Pearson correlation test and regression analysis. RESULTS: Pearson correlation test showed a high correlation (r = 0.94) between the PeSI and physiological strain index (P = 0/001). It was also observed a high correlation between the PeSI and the oral temperature (r = 0.78, P = 0/001) and the heart rate (r = 0.90, P = 0/001). In addition, there was found a moderate correlation (r = 0.71) between the PeSI and the wet bulb glob temperature (P = 0/001). However, there was no correlation between the PeSI and the body mass index (r = 0.0009, P = 0.79). CONCLUSIONS: The research findings showed when there is no access to other forms of methods to evaluate the heat stress, it can be used the PeSI in evaluating the strain because of its favorable correlation with the thermal strain.

Development and Validation of a Questionnaire for Preliminary Assessment of Heat Stress at Workplace.

BACKGROUND: Current heat stress indices are not completely suitable for heat strain screening in developing countries due to their inherent and applied limitations. The aim of this study was development of a questionnaire method entitled "Heat Strain Score Index" (HSSI) in order to perform a preliminary assessment of heat stress at work. METHODS: This research included six phases (i) Item generation (ii) Content validity (iii) Reliability analysis (iv)Structure validity (v) Concurrent validity and (vi) Classification of thermal risk level. In item generation phase, 40 items were identified to have impact on the heat strain. Content validity was evaluated by occupational health specialists. RESULTS: In consistency assessment, Cronbach's coefficient (α) of items was 0.91. Exploratory factor analysis on items HSSI draft identified four subscales which explained 71.6% of the variance. Correlation between the HSSI score with aural temperature was 0.73. Cut-off point; sensitivity and specificity for upper no thermal strain zone were 13.5, 91% and 50%, respectively. Whereas Cut-off point, sensitivity and specificity for lower thermal strain zone were 18, 86% and 73%. CONCLUSIONS: The results showed that 18 variables that were measurable through subjective judgment and observation in the HSSI scale covered heat stress key factors. This scale demonstrated reliability and initial validity in scale were suitable. Therefore HSSI scale for primary evaluation heat stress is appropriate.