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: Heat stress is one of the hazardous agents in the steel industries which can threaten the health and safety of workers and lead to serious occupational diseases. The aim of the study was to assess the heat stress in the steel industries and compare PHS (Physiological Strain Index), WBGT (Wet-Bulb Globe Temperature), DI (Discomfort Index) and HSI (Heat Stress Index) indices for the estimation of heat stress and to determine the optimum index for steel industries.
 

Material and Method: This descriptive-analytic study was conducted among 220 workers engaged in two steel industries in Iran. Environmental and physiological parameters were measured according to ISO 7726 and ISO 9886 in three times of measurement, and finally the time-weight average of the heat stress indices were calculated. All data were analyzed using SPSS ver.  20.
 

Result: The time-weight average of WBGT (28.28 oC), DI (29.11 oC), HIS (65.7 %) indices were higher than the recommended limits. Physiological parameters (oral, tympanic and skin temperatures, systolic and diastolic pressures and heart rate) had the greatest value in the second time of measurement (afternoon). WBGT index comparing to the PHS, DI and HSI indices had highest correlation with oral, tympanic and skin temperatures and heartbeat (r=0.314 , 0.408 , 0.459 , 0.302, respectively; P < 0.05), while systolic and diastolic blood pressures showed no significant correlation with WBGT (P > 0.05). The WBGT index had the highest correlation with studied indices which was 0.945, 0.681 and 0.600 for DI, PHS and HSI, respectively.
 

Conclusion: This study assessed the optimal index with regard to the physiological parameters, and it was concluded that the WBGT index has the highest correlation with the most of physiological parameters, and therefore, WBGT index can be the most optimum index to heat stress assessment   in the studied steal industries.

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Introduction: Working in hot and harsh weather conditions can cause heat related diseases and in some cases, even can lead to death. Risk assessment of heat stress in these environments is of particular importance. As there are many factors that could affect the heat stress, therefore, an index should be applied that could properly reflect the effect of all of these factors.
Material and Method: Initially a five-member expert team was established. Then, the weight of each variable was determined by the fuzzy analytical hierarchy process (FAHP) method. In next step, five work stations of the casting process evaluated applying fuzzy TOPSIS (FTOPSIS) method and the risk of heat stress prioritized in these stations. Lastly, the Pearson’s correlation coefficient was used to determine correlation between the results of proposed method with WBGT index.
Result:  The weights of three main variables including task characteristics, working environment, and worker characteristics was determined as 0.279, 0.526, and 0.195. The risk priority of the five work stations including, stocking, melting furnace, pouring and casting, polishing, and warehousing was established as S1= 4, S2= 2, S3= 1, S4= 3, and S5= 5. The Pearson’s correlation coefficient between the similarity index (CCi) and WBGT was 0.97.
Conclusion: From three main variables that can affect the heat stress, “Working Environment” has main impact in the risk assessment process; therefore, the most efforts must be focused on controlling this variable. The proposed method in this study has the capability of concurrent quantitative and qualitative assessment of factors that could affect the heat stress and can minimize the uncertainties in the risk assessment process relying upon the fuzzy sets.

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Introduction: Many studies, especially in recent years, have evaluated and controlled the occupational heat stress in Iran using environmental indices. However, so far, no comprehensive study has been conducted to review and classify these studies. Therefore, this study aimed to review and investigate the occupational studies performed by environmental heat stress indices in Iran.
Material and method:  In the present study, the published articles from 2000 to 2016 were searched using Persian and English keywords including heat stress, heat strain, hot condition, warm condition, occupational health, thermal environment and Iran. Search of articles was performed in databases such as Web of Science, Google Scholar, PubMed, Scopus, Science Direct, SID, Magiran, Civilica, Iran Medex, Barakatkns and Irandoc. In total, 323 articles were found and 134 articles of them, based on the exclusion criteria, were selected and included in this study. 
Results: Based on the results, most numbers of the studies, with 93.3 percent of the total researches related to published article, have been carried out between years of 2010 to 2016. As well as, most of studies with 61.9 percent were related to the indoor industrial environments. Most of studies were also performed in cities of Isfahan with 31.08 percent, Tehran with 16.89 percent, and Assaluyeh with 11.48 percent, respectively. As well as, WBGT index with 76 percent and the UTCI and PHS indices with 0.6 percent had the highest and lowest usage in all environments and industries, respectively. In addition, the results showed that WBGT index had most usage in industries of melting and casting with 15.7 percent, petroleum with 8.3 percent, and outdoor small occupations with 8.3 percent, respectively. Based on the results, the industries of the refinery, steel, glasswork, melting and casting, mines, and ship repairs have the highest mean values of WBGT index, respectively.
Conclusion: The results showed the need to more attention of researchers for conducting studies in outdoor environments, in different cities of Iran, on development and validation of novel heat stress indices, and on implementation and evaluation of control measures in the environments with high heat stress.

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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: Chlorpyrifos is an organophosphorus insecticide that can produce reactive oxygen species, and oxidative stress in the kidney. On the other hand, rosemary extract is an antioxidant playing a protective role against free radicals. Therefore, the aim of this study was to evaluate the oxidative stress in rat kidney due to the exposure to chlorpyrifos and to assess the antioxidant effect of two concentrations of 100 and 200 mg / kg rosemary extract on the nephrotoxicity caused by this pesticide.
Material and method: In the current study, 30 male Wistar Rats, weighing 200-220 g were used. They were randomly divided into five groups and selected as the study groups, each group including six rats  for further comparison. They were as following groupd: Group І: served as control (received dissilated water, i.p) , Group П: the chlorpyrifos exposure group (13.5 mg / kg, i.p.), Group Ш: the group exposed  to rosemary extract (100 mg / kg) by gavage, Group ІV: the exposure group with rosemary 100 mg / kg concentration (by gavage) and after 30 minutes exposure to chlorpyrifos (13.5 mg / kg, i.p.) and Group V: simultaneous exposure of rosemary 200 mg / kg concentration (by gavage) and after 30 minutes exposure to chlorpyrifos (13.5 mg / kg, i.p.). After 2 and 4 weeks, the rats were weighed and killed. A section of kidney tissue was examined for changes of Malondialdehyde (MDA) and Glutathione peroxidase (GPx) and another section was tested for histopathological alterations.
Results: The results showed that chlorpyrifos significantly damaged the kidney tissue and altered the activity of GPx and MDA compared to the control group, as well as it damaged the kidney tissue. Moreover, the simultaneous exposure to chlorpyrifos and rosemary extract with concentration of 100 mg/kg significantly made modifications to the MDA and GPx levels. In addition, with the increasing of rosemary doses from 100 to 200 mg / kg, changes in the levels of MDA and GPx were closer to those of the control group.
Conclusion: The rosemary extract can reduce the oxidative stress caused by chlorpyrifos and, therefore, can be used to treat the poisoning caused by this pesticide.

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Introduction: Stress is one of the major problems of living in industrial societies. Job and career issues are the most important causes of stress. Job stress is one of the important factors in causing psychological injury and illness in staff and decreasing productivity in organizations. Since human resources are among the most important assets of any organization, identification of the factors causing job stress is very crucial. Therefore current study aimed to investigate the causes of occupational stress in the staff of different units of the legal medicine centers in the Northwest Provinces.
 
Materials and Methods: A Descriptive-analytical study was conducted was designed and conducted on 166 employees of the various units of the legal medicines centers of Tabriz, Urmia, Ardebil and Zanjan cities by census statistical method during 2016-2017. Data were collected using questionnaires consist of demographic information and Cooper job stress questionnaire. The  collected  data  were  analyzed  by  means  of  SPSS  software  using  t-test  for  independent  groups,  ANOVA,  chi square, Pearson and  Spearman  correlation  coefficients, at the significant level of P<0.05.
 
Results: It was found that about 50% of the staff had moderate job stress and more than 12% had severe job stress. The comparison of mean job stress between healthy and ill individuals showed that the patients had a higher mean of job stress than healthy individuals, and this difference was statistically significant (P<0.001). The study of interference between work and life issue (family) also showed that the people whose work always interferes with their life issues had higher mean job stress than the other two groups and the difference was statistically significant (P<0.001). The result of this study also showed that there is a significant direct relationship between job stress and smoking (P<0.045), work interference and life issue (P<0.001), and a significant inverse relationship (P<0.044) with literacy.  Lower incomes, shifting the place of work, the heavy work, the ignorance of the managers to work problems, dealing directly with the people, the pressures due to the completion or working against deadlines, and the lack of hope for job promotion, respectively, are the factors causing stress in the organization.
 
Conclusion: Compared with employees of other organizations, the legal medicines staff seemed to have a much higher prevalence of stress. The organizational authorities could help staff to improve the quality of life and reduce occupational stress by creating the correct communication, desirable support and generating the appropriate environment for job activities.

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Introduction: Many studies have been carried out on the effects of heat stress on cognitive functions, but the results are contradictory. Therefore, this study was conducted to review the effect of heat stress on cognitive functions.
Material and method:  In this study, all English articles conducted on effect of heat stress on cognitive, perceptual, and psychomotor functions from 1970 to 2018 were reviewed. For this, articles with keywords such as heat strain, heat stress, cognitive function, memory, comprehension, psychomotor, reaction time, mental performance, mood, mental response, error, task performance, fatigue, alertness, hyperthermia, and heat exhaustion in the  Scopus, Web of Science, Science Direct, Pub Med, Springer, Wiley Online Library and ProQuest databases were searched. Out of 157 retrieved articles, 39 articles were finally reviewed according to the inclusion criteria.
Results: Out of 157 retrieved articles related to the topic, according to the inclusion criteria, 39 articles were finally considered for review. Among this articles, 9 (%23) articles were published before 2000 and 30 (%77) after 2000. Two articles were in athletes, four articles (%10.2) in workers, four articles (%10.2) in students, four articles (%10.2) in military soldiers and twenty-five articles (%64.2) were conducted in ordinary people.Based on the results, heat stress was identified as a detrimental factor for decreased cognitive functions such as reading comprehension, memory, focus, mathematical processing, tracking test, reaction time, perception  and decoding text and numeric messages, visual alertness, mental computing, text reading , hidden figures test and verbal fluency.
Conclusion: Based on the results of these studies, heat stress has been introduced as a detrimental factor for disrupting cognitive functions, but conclusion based on the results of studies is a systematic method is difficult because many confounding variables such as type of work, exposure time, skill and adaptation plays a big role.

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Introduction: Occupational stress is known today as one of the biggest challenges to higher education policy-makers. Students with high levels of stress find themselves lacking in self-confidence, vulnerable in controlling academic processes, and unable to compensate for clinical weaknesses. The main purpose of this study was to assess the levels of occupational stress among clinical dental students of Alborz University of Medical Sciences, Alborz, Iran.
Material and Methods: This study was a descriptive-analytic research with a cross-sectional design. The statistical population included all dental clinical students enrolled in the 7th, 9th, and 11th semesters in 2018 (n=84). According to the Krejcie and Morgan’s table, the sample size was 70. The data were also collected through the Osipow Occupational Stress Questionnaire, and then analyzed using the SPSS Statistics software (ver. 22). Besides, t-test was employed to investigate the relationship between variables and stress.
Results: The results revealed that the mean score of the students was 150.8. The mean total stress in the age group above 26 years was also 158 and that was 147 for those under the age of 26 (P-value=0.027). Besides, the mean score of overall occupational stress was equal in women and men. Comparisons also demonstrated that students in the 9th and 11th semesters (mean=161) were undergoing more stress than the ones enrolled in the 7th semester (mean=147) (P-value=0.014).
Conclusion: It was concluded that these clinical dental students were suffering from moderate-to-severe occupational stress. Likewise, older students had more stress than younger counterparts did. As well, male and female students’ levels of occupational stress were the same. Resolving this issue accordingly required special attention by higher education policy-makers to provide support and counseling in this respect.

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Introduction: Determining methods for assessing heat stress in different work environments is one of the major challenges for researchers in this field. The purpose of this study was to validate WBGT index and heat pressure assessment (HPA) by some physiological responses in Iranian South Oil Company.
Material and Methods: This descriptive-analytical study was carried out on 154 employees of Kharg, Asalouyeh and Mahshahr oil terminals recruited from three different working conditions including indoor, outdoor and rest environments in the summer. The amount of heat stress in the workplace was evaluated by WBGT index HPA method. To meet this purpose, the environmental parameters i.e., temperature, wet temperature, radiation temperature, relative humidity, water vapor pressure and air flow rate were determined. In addition to the direct reading method by the WBGT meter, ISO 7243 was used to calculate the WBGT index. In order to validate the heat stress indicators, physiological parameters of oral temperature, tympanic temperature and work metabolism were measured.
Results: The results of paired sample t-test showed a significant difference between WBGT index and HPA in indoor and outdoor environment (P<0.05). Moreover, there was a significant difference between the physiological indices of oral and tympanic temperatures and work metabolism in the indoor and outdoor environment (P<0.05). Furthermore, the correlation test was significant between WBGT index as an independent variable and HPA as a dependent variable (P<0.05)  and showed a high correlation (R2=0.914) between WBGT index with oral temperature and tympanic temperature . Also, the rate of work metabolism was significantly related with the aforementioned parameters (P<0.05) and was equal to R2=0.423, R2=0.335, R2=0.552, respectively. The correlations were also significant between HPA with Oral temperature, tympanic temperature and work metabolism (P<0.05)and were equal to R2=0.632, R2=0.605, R2=0.557, respectively. The results showed also that the correlation rate between the HPA with physiological parameters is stronger than that between physiological parameters with the WBGT index.
Conclusion: This study showed that WBGT and HPA methods are useful for assessing the heat stress of Iranian South Oil Company. Also, the HPA method is more reliable for assessing heat stress in these regions.

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Introduction: Damage to occupational health is one of the major challenges in the industry. Various studies have shown that productivity in industries has a significant relationship with occupational health. In addition, employee’s health in the workplace can be affected by a variety of variables i.e., job stress, job satisfaction, and work in unconventional shifts. Therefore, the purpose of this study was to evaluate the causal relationships of shift work, job stress, job satisfaction with the occupational health level in a petrochemical industry.
Material and Methods: This cross-sectional study was implemented in 2017. The study sample consisted of 20 HSE experts selected using purposeful judgment sampling. A 4×4 matrix questionnaire consisting of four main parameters i.e., shift work, job stress and job satisfaction with occupational health level, was used for data acquisition. Data analysis was done using MATLAB software and Fuzzy DEMATEL method. Also, for each variable, two key values of D+R and D-R were calculated. These values show the degree of interaction and the type of interaction of the variable with other variables, respectively.
Results: Sixty percent of the experts participating in this study were male and 40.0% were female. Only 10.0% of the participants had a PhD degree. In addition, the mean age and the mean work experience of the subjects were 39.64±9.34 and 10.22±7.10 years, respectively. The parameters of shift work and job satisfaction were identified as an effective factor due to the positive values of D-R while occupational health variable with negative value of D-R, was considered as an affected factor. In addition, these results showed that the effect of these parameters on health is different with both direct and indirect mechanisms.
Conclusion: Using the Fuzzy DEMATEL method, our findings indicated that occupational health in the large industries can be influenced by different parameters with different sizes. Considering the interactions among these parameters in health analysis and the affecting factors, therefore, is very important. So, the health level in challenging industrial environment such as petrochemical industries can be affected by shift work as a root cause. This root cause, along with job satisfaction, has a significant effect on increasing stress levels and reducing health levels. Accordingly, any action to increase the health level should focus on improving shift patterns and increasing the level of job satisfaction of employees as a pivotal root and affecting causes on health level.

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Introduction: These days, there is a consensus that emotional intelligence plays an important role in the success of individuals in different areas of life. Persons with higher emotional intelligence had lower stress in dealing with demands and pressures in the workplace. The purpose of this study was to use artificial neural network to predict job stress and to compare the performance of this model with the multivariate regression model.
Material and Methods: In order to do that, 892 participants were selected randomly in different job categories. Then, 15 dimensions of Bar-On questionnaire, 10 job categories, age and education were considered as input variables and 7 dimensions of health and safety executive HSE were determined as output variables in models.
Results: The results revealed that an artificial neural network with hyperbolic tangent and sigmoid transfer functions respectively in hidden and output layers with 375 hidden neurons had significantly better performance than multivariate regression. So that, correlation of predicted values and job stress were only between 0.192-0.364 in regression model, but neural network had at least correlation 0.527 in all dimensions of job stress.
Conclusion: In predicting job stress using emotional intelligence, artificial neural network method was much better than multivariate regression model.

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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: Prevention of heat-related diseases requires the participation of the workers. For this reason, the aim of this study was the development and validation of the tools for evaluating awareness and practice related to heat stress among the workers of warm workplaces.
Material and Methods: The various items and factors related to the awareness and practice of the workers were identified by the literature review. Then, several questions for evaluating these items were designed. In the next step, the reliability and validity of the questionnaires were appraised using calculating the content validity ratio (CVR) and content validity index (CVI), and Cronbach’s alpha coefficient, respectively. After that, these questionnaires were completed by 2338 employees of six industries in various regions of Iran. Finally, collected data were analyzed using SPSS software.
Results: In total, 77 questions, including 53 questions on awareness and 24 questions on practice in six groups of water and beverages, food, snacks and additives, heat exchange, thermal strain risk factors, clothing and heat protection equipment, and heat-related disorders and body reactions, were designed. The values of content validity index (CVI) of remained questions in the questionnaires of awareness and practice were equal to 0.954 and 0.824, respectively. The values of Cronbach’s alpha coefficients of these questionnaires were calculated by 0.755 and 0.716, respectively. The values of the chi-square divided by degrees of freedom (CMIN/DF) and root mean square error of approximation (RMSEA) in the construction of the awareness questionnaire were computed as 4.58 and 0.079, respectively. These values in the construction of the practice questionnaire were calculated by 2.33 and 0.084, respectively.
Conclusion: The results showed that the designed questionnaires had appropriate reliability and validity and could be used to evaluate the awareness and practice in warm workplaces.

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Introduction: Studies show that in many cases, environmental hazardous agents such as heat, noise, as well as chemical pollutants cause adverse health effects through the mechanism of oxidative stress. This study has examined the effect of exposure to noise and whole-body vibration (WBV) on some parameters of oxidative stress (enzyme superoxide dismutase (SOD), total antioxidant capacity (TAC), and malondialdehyde (MDA)) of workers in a foundry industry.
Material and Methods: The workers were selected based on the calculations related to the sample size and taking into account the inclusion criteria as well as completing the informed consent form. The level of exposure to noise and WBV was measured according to ISO 9612 and ISO 2631, respectively. For each worker, the time-weighted average was calculated. The level of exposure of workers to the studied stressors was divided into three categories: low, medium, and high. The blood samples were taken from all participants between 7-9 am. Then, via ELISA method according to the protocol of the kit manufacturer, the samples were prepared and analyzed. Univariate analysis of variance was performed to determine the “effect size” of each physical stressors on the studied parameters.
Results: The mean levels of MDA, SOD, and TAC among participants were 22.48 (11.19) nmol / ml, 61.28 (10.97) U / ml, and 1.64 (0.90) mM, respectively. Among the exposure variables, noise had the largest effect on MDA level (B = 0.090), which was not statistically significant (P = 0.865). WBV had the largest effect on SOD level (B = -1.469) which was statistically significant (P = 0.016). None of the studied variables had a significant effect on the TAC level; however, among the exposure variables, the greatest effect was related to WBV (B = -0.077; P = 0.133).
Conclusion: The effect of noise on oxidative stress parameters was not statistically significant. The effect of whole-body vibration on oxidative stress parameters except SOD was not statistically significant. Noise and WBV had increasing effect on MDA and decreasing one on SOD and TAC levels.

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Introduction: Health workers, especially nurses, are facing a high risk of contracting the COVID-19 and consequent mental disorders such as stress, anxiety and depression. We aimed to study the relationship between anxiety, stress and the protective behavior of nurses during the Covid-19 pandemic.
Material and Methods: This cross-sectional study was conducted on nurses working in COVID -19 referral hospitals in Qazvin, Iran, in 2020. Out of 645 nurses working in two hospitals, 260 of them were selected randomly. Three questionnaires including demographic and contextual information, COVID-19 anxiety, stress and precautionary behaviors against COVID-19 were used. Descriptive statistical methods, Pearson correlation, t-test and one-way analysis of variance and binary logistic regression analysis were applied at 95% confidence interval.
Results: The prevalence of anxiety symptoms in nurses was 32.08%, the mean score of protective behavior was 18.45+5.66 and the maximum score was 22.06+4.7. The negative relationship between anxiety and nurses precautionary behavior) β=-0.36, P<0.05) and the significant effect of COVID-19 stress on nurses’ behavior) β=-0.22, P<0.05) were confirmed. Furthermore, adding stress as an interfering factor, affirmed the mediating role of stress in the relationship between anxiety and nurses’ precautionary behavior (β=-0.18, P<0.05). Nurses under 35 years of age were more likely (OR=1.62, P=0.004) to follow the protective rules; those with 6 to 10 years of hospital experience were respectively 32 times and 37 times more probable to use personnel protective equipment (PPE) (OR=1.32, P=0.002) .
Conclusion: The probability of effective use of PPE and observance of protective guidelines among nurses with severe and very severe anxiety levels was less than their counterparts. While in those with controlled level of stress level such obedience was much more probable. Therefore, all health service providers, need to develop supportive programs to emphasize on the promotion of employees’ mental health.

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Introduction: Climate change and hot processes in the workplaces has led to an increase in the effects of heat stress on employed people, which has become a major concern, especially in tropical and subtropical countries. Early detection of biomarkers in induction of heat stress-related DNA damage can be used in the identification and evaluation of health and safety, including occupational health professionals, as well as to prevent serious diseases caused by heat stress in various occupations with the nature of hot processes or to help different warm seasons of the year. Therefore, this review study was conducted to identify diagnostic biomarkers heat stress induced- DNA damage in occupational exposure.
Material and Methods: Databases such as PubMed, Scopus, Google Scholar, and Web of Science were systematically searched to meet the study’s goals. Moreover, references to relevant publications were examined. Finally, suitable articles were selected and analyzed using the inclusion (studies on different occupations, different biomarkers in hot work environments, all articles published without time limit until the end of April 2022 , and English and Persian language)  and exclusion criteria.
Results: The results of search in databases showed that 9234 articles were found in the initial search. After removing duplicate and unrelated articles, 2209 eligible articles were selected. Based on abstract full-text screening, 7166 studies were excluded, and based on abstract full-text screening, 21 studies were not accessible. Finally, seven articles were selected to be reviewed. The evidence showed that diagnostic biomarkers included the measurement of 8-hydroxy-2-deoxyguanosine (8-OHdG), micronuclei semen quality, heat shock proteins (HSP70), and leukocytes were extracted to heat stress induced- DNA damage in occupational exposure.
Conclusion: Based on a review of studies,  biomarkers identified are suitable for heat stress induced- DNA damage as a result of occupational exposure to extremely high heat climate conditions. Understanding and identifying appropriate biomarkers in inducing DNA damage can help health and safety professionals determine the amount and magnitude of heat stress responses in occupational exposure to different temperatures and take appropriate measures and interventions to control and reduce the hazard effects of thermal stress. This study can also be considered as a preliminary study for research in the future.

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Introduction: Many industries have multiple factors harmful to health, leading to simultaneous exposure of these factors to each other. Noise is one of the most common physical parameters in the work environment. On the other hand, heat is also increasing due to various energy processes in industries. Therefore, this study was conducted with the aim of determining changes in physiological parameters and visual-auditory attention in acute exposure to heat and noise.
Material and Methods: In this experimental study, 72 individuals (36 men and 36 women) aged between 23 and 33 years participated according to the inclusion criteria. In total, 12 different test modes were performed (3 temperature levels and 4 noise pressure levels). The test was conducted for each person in 4 steps during a specific day. The duration of exposure to each condition was half an hour, and a half-hour rest was given between each test condition. Saliva samples of each subject were collected before and immediately after exposure to noise and heat. Also, The Integrated Visual and Auditory (IVA) was recorded by the participants simultaneously.
Results: The results of combined exposure to noise and heat on visual and auditory attention showed that only two modes of combined exposure, SPL95+WBGT34 and SPL95+WBGT29, caused a significant increase (P < 0.05) in mental workload and a significant decrease (P < 0.05) in visual and auditory attention. In addition, the results showed that independent exposure to noise at the levels of 85 and 95 dB and exposure to heat at higher temperature levels of 34 and 29 degrees Celsius cause a significant increase (P < 0.05) in salivary cortisol after exposure. The results of the effect of combined exposure to noise and heat on salivary cortisol showed that three experimental modes of combined exposure (SPL85+WBGT34, SPL95+WBGT29, and SPL95+WBGT34) caused a noticeable and significant (P<0.001) increase in salivary cortisol.
Conclusion: Indeed, salivary cortisol can be recommended as a physiological index to evaluate noise and heat exposure. It’s also noteworthy that salivary cortisol is more affected by noise and heat exposure than cognitive performance.