Climatic conditions and concentrations of BTEX compounds in atmospheric media.

Climatic and meteorological conditions are among the factors affecting the ambient concentrations of BTEX compounds. This systematic review and meta-analysis aimed to interrogate the seasonal effect of climatic conditions on the concentrations of BTEX compounds. Three electronic bibliographic databases including Scopus, PubMed, and Web of Science were systematically searched up to November 14, 2023. The search algorithm followed PRISMA guidance and consisted of three groupings of keywords and their possible combinations. For various climatic conditions, the overall mean and 95% confidence interval (CI) of effect size related to BTEX concentrations were calculated using a random-effect model. In total, 104 articles were included for evaluation in this review. BTEX ambient concentration was higher in winter (ranging from 36 out of 79 relevant studies for xylene to 52 out of 97 relevant studies for benzene) followed by summer and autumn. For humidity conditions, the highest exposure values for BTEX were detected for rainy weather (ranging from 3 out of 5 relevant studies for toluene and xylene to 4 out of 5 relevant studies for benzene and ethyl benzene) compared to dry conditions. The pooled concentration (µg/m3) of benzene, toluene, ethyl benzene, and xylene were computed as 2.61, 7.12, 2.21, and 3.61 in spring, 2.13, 7.53, 1.61, and 2.75 in summer, 3.04, 9.59, 3.14, and 5.50 in autumn, and 3.56, 8.71, 2.35, and 3.91 in winter, respectively. Moreover, the pooled concentrations (µg/m3) of BTEX were measured as 2.98, 7.22, 1.90, and 3.03 in dry weather and 3.15, 6.30, 2.14, and 3.86 in rainy or wet weather, respectively. In most seasons, the ambient concentrations of BTEX were higher in countries with low and middle incomes and in Middle Eastern countries and East/Southeast Asia compared to those in other regions (P < 0.001). The increasing concentrations of BTEX in winter and autumn followed by the summer season and during rainy/wet weather appear to be reasonably consistent despite variations in study methods, quality, or geography. Therefore, it is recommended that more serious control measures are considered for decreasing exposure to BTEX in these climatic conditions.

Occupational stress and musculoskeletal disorders in firefighters: the mediating effect of depression and job burnout.

The firefighting profession carries a heightened risk of musculoskeletal disorders. A firefighter's job is physically demanding and includes activities such as running, climbing, dragging, and lifting. Often, these tasks are unpredictable, performed in harsh environments, and have been found to cause psychological stress. The purpose of this study was to investigate the effects of occupational stress on work-related musculoskeletal disorders (WRMSD) in firefighters. In addition, the mediating effects of depression and job burnout on proposed relationships were examined. Data informing this study were collected using a survey questionnaire. The survey questionnaire included the Beck Depression Inventory, the Center for Epidemiological Studies Depression Scale (CES-D), the Maslach Burnout Inventory, the Post Traumatic Stress Disorder Inventory (PCL), and the Nordic Musculoskeletal Questionnaire. Collected data were analyzed using structural equation modeling approach in AMOS. The results of the 2339 responding firefighters suggest that work related stress is positively related to WRMSDs in firefighters and can lead to musculoskeletal symptoms through four paths, being emotional exhaustion, personal accomplishment, CES-D total score, and depersonalization. Through depersonalization, job stress had the most significant impact on musculoskeletal symptoms (coefficient = 0.053). Furthermore, the results showed that post-traumatic stress disorders (PTSD) can affect musculoskeletal symptoms through ten paths, again through depersonalization, PTSD had the most significant impact on musculoskeletal symptoms (coefficient = 0.141). The results of this study suggest that organizations should design interventions and policies to prevent and manage occupational stress, depression, and job burnout to negate its undesired consequences on firefighters' health (i.e. WRMSD).

Relationships between job stress, post-traumatic stress and musculoskeletal symptoms in firefighters and the role of job burnout and depression mediators: a bayesian network model.

INTRODUCTION: Job stress, post-traumatic stress disorder (PTSD), and negative psychological outcomes in firefighters can be caused, or aggravated, by their work. These mental disorders can impart musculoskeletal symptoms. This study aimed to investigate relationships between musculoskeletal and psychological disorders in a population of firefighters using a Bayesian network model. METHODS: This cross-sectional study, conducted in 2022, included 2339 firefighters who completed questionnaires during their rest periods. The questionnaires comprised of demographical information, the Occupational Stress Questionnaire-HSE, the PTSD Checklist, Maslach Burnout Inventory, Center for Epidemiologic Studies - Depression scale (CES-D), and Nordic Musculoskeletal Questionnaire. GeNIe academic software was used to analyze the Bayesian network. RESULTS: High job stress and high PTSD each increased the probability of musculoskeletal symptoms by 34%. When combined, high job stress and high PTSD increased the probability of musculoskeletal symptoms by 37%. Among the mediator's burnout and depression, depression had the highest association with musculoskeletal symptoms. CONCLUSIONS: Job stress and PTSD can increase musculoskeletal symptoms and are influenced by psychological mediators (like burnout and depression). Adopting preventive and therapeutic measures to mitigate job stress and PTSD, mitigate and rehabilitate WMSD, and manage associated mediators are critical for the mental and physical health of firefighters.

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.

The global prevalence of musculoskeletal disorders among firefighters: a systematic review and meta-analysis.

This systematic review and meta-analysis study aimed to explore the global prevalence of musculoskeletal disorders (MSDs) among firefighters. A systematical search was performed in three international academic databases (Scopus, PubMed and Web of Science). Overall, 31 articles were included in this review. The pooled prevalence of total MSDs in firefighters was identified as 41% (95% confidence interval [CI] [33, 50]). The prevalence of MSDs in neck, shoulders, upper back, lower back, upper extremity and lower extremity was 9% (95% CI [7, 10]), 11% (95% CI [8, 15]), 8% (95% CI [5, 12]), 31% (95% CI [27, 34]), 13% (95% CI [9, 17]) and 16% (95% CI [14, 18]), respectively. No statistically significant relationship was observed between prevalence of MSDs and year of study, mean age, size of sample, duration of prevalence, region or income level. Demographic, occupational and medical condition factors were identified that can create these disorders among firefighters.

Determination and prioritization of factors affecting the occurrence of needle stick injuries among healthcare workers using techniques of Delphi and fuzzy analytical hierarchy process (FAHP).

INTRODUCTION: Needlestick injuries (NSIs) are a major hazard in the workplace for healthcare workers. To prevent these injuries, it is essential to determine the important factors affecting the occurrence of them. This study aimed to identify, classify and prioritize these factors using techniques of Delphi and fuzzy analytical hierarchy process (FAHP). METHODS: This descriptive-analytical study was conducted in 2022. Firstly, the factors affecting the occurrence of needlestick injuries were identified by the literature review. Moreover, the Delphi technique was used to identify the factors. 20 experts (physicians, nurses, and occupational health experts) participated in the steps of the Delphi method. Then, these factors were grouped into six groups. In the next step, the fuzzy analytical hierarchy process (FAHP) was applied to prioritize the factors. For this purpose, the pairwise comparison questionnaire was designed and filled out by 20 experts. Finally, data were analyzed using MATLAB software (version 2018a). RESULTS: 42 factors (31 factors extracted from the literature review and 11 factors obtained from the Delphi technique) were identified in this study. These factors were categorized into six groups. Based on the results, the relative weight of non-demographic personal factors, tool and technology factors, job factors, organizational factors, demographic personal factors, and environmental factors were computed by 0.200, 0.185, 0.184, 0.157, 0.142, and 0.133, respectively. CONCLUSION: These results determined the importance of the factors affecting the occurrence of needlestick injuries. These findings can be useful for planning preventive measures.

The effects of occupational noise on sleep: A systematic review.

Noise exposure in the workplace is one of the most common occupational hazards, which can affect sleep in the human. The effects of occupational noise can be different than that of environmental or social noise. This study aimed to conduct a systematic review on the effects of occupational noise on various characteristics of sleep. In this study, three electronic bibliographic databases (Scopus, PubMed, and Web of Science) were systematically searched up to 14 December 2022. The search algorithm included two sets of keywords and possible combinations. The first group was keywords related to occupational noise, and the second group was keywords related to sleep. A total of 2082 articles were identified in the initial search, and 2034 articles were excluded based on exclusion criteria or lacking inclusion criteria. Finally, 48 articles met the inclusion criteria and were selected for final review. Among 13 articles identified as high quality, all studies (100%) showed that noise had a significant effect on sleep among workers in various occupations. Among 17 articles with moderate quality, thirteen studies (76.47%) indicated that noise had a significant effect on sleep among workers in different occupations. Among 18 low-quality articles, fifteen studies (83.33%) showed that noise had a significant effect on sleep. 41 out of 48 studies (85.42%) found that occupational noise can negatively impact sleep among employees in various occupations. There are at least four potential pathways for this effect, including the physiological effect of daytime noise exposure, the psychological effect of daytime noise exposure, the effect of nighttime noise exposure, and the effect of hearing problems due to noise.

Health risk assessment of exposure to various vapors and fumes in a factory of automobile manufacturing.

This study aimed to comprehensively evaluate the health risk of exposure to various vapors and fumes in a factory of automobile manufacturing. This study was performed in 2021 on 115 workers. Vapors and fumes were gathered by the adsorbent tubes of activated charcoal and mixed cellulose esters (MCE) membrane filter, respectively. The flow rate for vapors and fumes were between 0.05 and 0.20 L per min and 1 to 4 L per min, respectively. After preparing, samples were analyzed. To assess the non-cancer and cancer risk of the pollutants, the method proposed environmental protection agency (EPA) was applied. The total concentration of copper (1.031 ppm), manganese (0.114), and 2-butoxyethanol (91.767 ppm) were found to be higher than The threshold limit values (TLVs). The values of non-cancer risk (HQ) due to exposure to vapors of benzene (6.583), toluene (1.396), ethyl benzene (1.212), xylene (31.148), 2-butoxyethanol (89.302), 2-propanol (4.695), 1,2,3-trimethylbenzene (1.923), copper (2.336), manganese (715.82), aluminum (3.772), and chromium (107.066) were higher than the acceptable limit. Moreover, the estimated LCR for benzene (2.15 × 10-4), ethyl benzene (3.97 × 10-4), vinyl chloride (1.25 × 10-4), and chromium (2.11 × 10-2) were higher than the threshold risk level set by EPA. It is emphasized that preventive measures are performed.

Summer and winter variations of BTEX concentrations in an oil refinery complex and health risk assessment based on Monte-Carlo simulations.

The summer and winter concentrations of BTEX pollutants were investigated in various workplaces of an oil Refinery, Iran. In total 252 air samples from the breathing zones of the following employees were collected: supervisors, safetymen, repairmen, site men, and all workers. Carcinogenic and non-carcinogenic risk values were calculated based on the USEPA methodology using Monte Carlo simulations. BTEX concentrations were higher in the summer than in the winter season for all workstations, especially for toluene and ethylbenzene. The mean values of exposure to benzene for repairmen and site men were higher than threshold limit value of 1.60 mg/m3 for both seasons. Non-carcinogenic risk (HQ) values calculated for summer season for benzene, ethylbenzene, and xylene in all workstations, as well as for toluene for repairmen and site men exceeded acceptable level of 1. In winter season the mean HQ values for benzene and xylene in all workstations, for toluene for repairmen and site men, and for ethylbenzene for supervisors, repairmen, and site men were also > 1. For all workstations definite carcinogenic risk was indicated as calculated LCR values for benzene and ethylbenzene exposure were higher than 1 × 10-4 in both summer and winter seasons.

Development and validation of a biological risk assessment tool among hospital personnel under COVID-19 pandemic conditions.

The need for a biological disease risk assessment method to prevent the contagion of these diseases, particularly among healthcare personnel, is crucial. Therefore, this study aimed to develop and validate a biological risk assessment tool for biological agents among hospital personnel under COVID-19 conditions. This cross-sectional study was performed on 301 employees in two hospitals. Firstly, we identified the items affecting the contagion of biological agents. Then, we computed the weight of the items using the Fuzzy Analytical Hierarchy Process (FAHP) method. We used the identified items and the estimated weights in the next step to develop a predictive equation. The outcome of this tool was the risk score of biological disease contagion. After that, we used the developed method to evaluate the biological risk of the participants. The ROC curve was also used to reveal accuracy of developed method. In this study, 29 items were identified and categorized into five dimensions, including environmental items, ventilation items, job items, equipment-related items, and organizational items. The weights of these dimensions were estimated at 0.172, 0.196, 0.255, 0.233, and 0.144, respectively. The final weight of items was used to develop a predictive equation. The area under ROC curves (AUC) was also calculated as 0.762 (95% CI: 0.704, 0.820) (p<0.001). The tools developed using these items had acceptable diagnostic accuracy for predicting the risk of biological diseases in health care. Therefore, one can apply it in identifying persons exposed to dangerous conditions.

Determining the effect of selected mental factors on turnover intention through two modulators - stress and resilience over COVID-19 period.

INTRODUCTION: Turnover intention among nurses has risen in an alarming rate since the onset of the pandemic. There are various underlying factors to turnover intention. The present study aims to determine the effect of a number of mental factors on nurses' professional-turnover intention through two modulators of stress and resilience over COVID-19 period. METHODS: The current cross-sectional study was conducted at three hospitals in Khuzestan Province, southern Iran, during the winter of 2021. To collect the data, given the restrictions in place during COVID-19 period, the web link of electronic self-reported questionnaires (including general health, mental workload, work-family conflict, resilience, job stress, corona fear, and turnover intention) were sent to 350 nurses through e-mail and other social media (WhatsApp and Telegram). Accordingly, they were asked to complete the questionnaire during rest periods within two weeks. Totally, 300 people (85% participation) filled out the questionnaires. Finally, a model was constructed in the Amos software. RESULTS: The results showed that the four independent parameters of decreasing general health, increasing mental workload, increasing WFCs and fear of COVID-19 can indirectly increase nurses' turnover intention by increasing job stress. Among these variables, the highest indirect effect coefficient on turnover intention was related to the general health parameter (-0.141). The results also demonstrated a negative correlation between job stress and resilience, with lower resilience raising job stress and, consequently, increasing intention to quit the job. CONCLUSION: Mental factors affecting turnover intension were identified in this study through path analysis. Therefore, it is recommended that the required resilience-enhancing measures to be taken by hospitals and nursing administrations to reduce psychological pressures caused by mentioned variables with the aim of minimizing job-related stress and fostering nurse retention.

Examining the effect of safety climate on accident risk through job stress: a path analysis.

BACKGROUND: Job stress is a probable mediator of the relationship between safety climate and accident occurrence. To demonstrate this, this study investigates the relationship between safety climate, job stress, and accident risk using a large number of surveys. The study will use structural equation modeling (SEM) to analyze the data collected from the surveys to examine the effect of safety climate on accident risk through job stress. METHODS: The study is a cross-sectional study that was conducted on 1,530 male workers of a petrochemical company. The subjects were asked to complete several questionnaires during rest periods, which included demographic information, the Nordic safety climate questionnaire (NOSACQ-50), and the generic job stress questionnaire (GJSQ). Additionally, data on the frequency and intensity of accidents among participants were gathered from the health unit of the company. Path analysis was conducted by structural equation modeling (SEM) in Analysis of Moment Structures (AMOS) software. RESULTS: The results revealed that the latent variable of safety climate with an effect coefficient of - 0.112 did not have a direct effect on accident risk (P = 0.343). However, safety climate with an effect coefficient of - 0.633 had an indirect effect on accident risk through job stress (P < 0.001). The total score of job stress had a significant direct effect (0.649) on accident risk (P < 0.001). Among the dimensions of safety climate, the variables of management's safety priority, commitment, and competence (- 0.108) and workers' safety commitment (- 0.107) had the highest indirect effect coefficients on accident risk. Among the dimensions of job stress, the highest indirect effects belonged to the variables of conflict at work (0.636), physical environment (0.631), and workload and responsibility (0.631), respectively. CONCLUSION: The results of the study revealed that job stress mediates the relationship between safety climate and accident risk. This finding suggests that organizations can potentially decrease accidents in industries by addressing and managing job stress in the workplace.

Global prevalence and associated factors of sleep disorders and poor sleep quality among firefighters: A systematic review and meta-analysis.

Lack of sleep can affect the health and performance of firefighters. This systematic review and meta-analysis estimated the global prevalence of sleep disorders and poor sleep quality among firefighters and reported associated factors. Four academic databases (Scopus, PubMed, Web of Science, and Embase) were systematically searched from January 1, 2000 to January 24, 2022. These databases were selected as they are known to index studies in this field. The search algorithm included two groups of keywords and all possible combinations of these words. The first group included keywords related to sleep and the second group keywords related to the firefighting profession. The relevant Joanna Briggs Institute checklist was used to evaluate study quality. Data from eligible studies were included in a meta-analysis. In total, 47 articles informed this review. The pooled prevalence of sleep disorders and poor sleep quality in firefighters were determined as 30.49% (95% CI [25.90, 35.06]) and 51.43% (95% CI [42.76, 60.10]), respectively. The results of a subgroup analysis showed that individuals in low- and middle-income countries (LMICs) had a higher prevalence of sleep disorders than those in high-income countries (HICs) but HICs had a higher prevalence of poor sleep quality than LMICs. Various factors, including shift work, mental health, injuries and pain, and body mass index were associated with sleep health. The findings of this review highlight the need for sleep health promotion programs in firefighters.

Noise exposure and the risk of cancer: a comprehensive systematic review.

The association between noise exposure and increased risk of cancer has received little attention in the field of research. Therefore, the goal of this study was to conduct a systematic review on the relationship between noise exposure and the incidence of cancer in humans. In this study, four electronic bibliographic databases including Scopus, PubMed, Web of Science, and Embase were systematically searched up to 21 April 2022. All types of noise exposure were considered, including environmental noise, occupational noise, and leisure or recreational noise. Furthermore, all types of cancers were studied, regardless of the organs involved. In total, 1836 articles were excluded on the basis of containing exclusion criteria or lacking inclusion criteria, leaving 19 articles retained for this study. Five of nine case-control studies showed a significant relationship between occupational or leisure noise exposure and acoustic neuroma. Moreover, four of five case-control and cohort studies indicated statistically significant relationships between environmental noise exposure and breast cancer. Of other cancer types, two case-control studies highlighted the risk of Hodgkin and non-Hodgkin lymphoma and two cohort studies identified an increased risk of colon cancer associated with environmental noise exposure. No relationship between road traffic and railway noise and the risk of prostate cancer was observed. In total, results showed that noise exposure, particularly prolonged and continuous exposure to loud noise, can lead to the incidence of some cancers. However, confirmation of this requires further epidemiological studies and exploration of the exact biological mechanism and pathway for these effects.

The impact of emotional intelligence and personality traits on the occurrence of unsafe behaviors and needle stick injuries among the nurses.

This study was aimed to investigate the effect of emotional intelligence and some personality traits on safe behavior and needle stick injuries among the nurses. This cross-sectional study was performed on 200 nursing staff of a hospital in Iran. To collect data, individuals were asked to complete several questionnaires, including demographic questionnaire, domain-specific risk-taking questionnaire, Rosenberg self-confidence questionnaire, Buss-Perry aggression questionnaire, Goleman emotional intelligence questionnaire, and safe behavior questionnaire. Also, the number of needlestick injuries in the participants was extracted from their medical records. Data were analyzed using the SPSS software (version 22), and path analysis was performed using AMOS software. The prevalence of needle stick injuries in the subjects was estimated by 45.5 percent. The results showed that increasing risk-taking, increasing aggression, decreasing self-confidence, and decreasing emotional intelligence reduced safe behavior and increased the number of needle injuries (P < 0.001). In the present study, some personal traits affecting the occurrence of needlestick injuries were identified. It is recommended that people without these negative traits are applied in dangerous occupations with a high probability of needle stick injuries.

The impact of ergonomic-educational interventions on reduction of musculoskeletal symptoms among employees of oil and gas installations in Iran.

BACKGROUND: Musculoskeletal disorders can cause increased absenteeism, costs, and injuries. OBJECTIVE: The present study was aimed to investigate the impact of ergonomic-educational interventions on the reduction of musculoskeletal symptoms among employees of oil and gas installations. METHODS: This interventional study was conducted on 1243 male workers of oil and gas installations in the south of Iran. The Nordic questionnaire and quick exposure check (QEC) method were used to evaluate the risk of developing musculoskeletal disorders in the participants. Then, the educational interventions via training sessions, designed educational booklets and leaflets, and prepared educational film were performed. Data were collected at the times of two months before and six months after the interventions. RESULTS: The prevalence of musculoskeletal symptoms, at least in one of the body areas, was equal to 71.28%. The results showed that the prevalence of these symptoms significantly decreased in all body areas after the educational interventions (P <0.028). The highest reduction rate occurred in the regions of wrists and hands (52.77%), knees (47.17%), and waist (47.13%), respectively. Moreover, the results indicated that the mean value of the total score of quick exposure check (QEC) had a meaningful decrease from 0.92 to 0.54 after the educational interventions (P <0.0001). CONCLUSION: The planned educational interventions efficiently reduced the prevalence of musculoskeletal symptoms and the ergonomic risk levels estimated by QEC in the research population.

Development of modified rapid entire body assessment (MOREBA) method for predicting the risk of musculoskeletal disorders in the workplaces.

BACKGROUND: Rapid Entire Body Assessment (REBA) technique is one of the tools developed for predicting the risk of musculoskeletal disorders based on the effective risk factors. This method has several limitations. The present study was aimed to develop the Modified Rapid Entire Body Assessment (MOREBA) method to more accurately predict the risk of musculoskeletal disorders. MATERIALS: This cross-sectional study was performed on 300 male workers of a steel factory with a variety of job tasks in Iran. Then, the information related to the various physical risk factors was extracted through observation of their duties and conversation with them. Also, the subjects were asked to complete the Persian version of Cornell musculoskeletal discomfort questionnaires (CMDQ). Then, a theoretical model was drawn in AMOS software. Computed coefficients were used to develop the MOREBA equation. In the end, the final scores were categorized by ROC curves, and the validation of the novel method was investigated using linear regression analysis. RESULTS: The parameters evaluated in the MOREBA method included contact stress, rapid and sudden movement, throwing motion, hand-arm vibration, whole-body vibration, temperature, and work-rest cycle in addition to the parameters of the REBA method, including awkward posture, coupling, force, load, static activity, and repetitive activity. The results showed that the strain produced by the physical risk factors with the total effect coefficient of 0.783 could significantly affect the musculoskeletal symptoms. The computed coefficients of the risk factors were applied to develop a novel index. The final score of the MOREBA method was categorized into four levels by optimal cut-off points of 12.37, 16.51, and 24.35. Based on the results, the MOREBA and REBA methods could justify 67 and 55% of the variations of musculoskeletal symptoms, respectively. CONCLUSIONS: The results revealed that modifications conducted in the REBA method were effective, and the MOREBA method can provide a more accurate prediction of the risk of musculoskeletal disorders.

Effect of tonal noise and task difficulty on electroencephalography and cognitive performance.

Objectives. The present study aimed to investigate the effect of tonal noise and task difficulty on electroencephalography (EEG) and cognitive performance. Methods. Twelve healthy volunteers participated in the present study. Four noise signals were generated by four prominence tone levels (0, 2, 5 and 9) at background noise levels of 55 dBA and frequency of 500 Hz using the Test Tone Generator from Esser Audio (USA). The participants were asked to perform the tasks with low, moderate and high levels of difficulty while exposed to the noises in an acoustics laboratory. The values of reaction time, correct rate and missed numbers were recorded during each step. Moreover, the EEG signals were measured. Results. The results showed that higher tone level and more task difficulty significantly decreased the correct rate, and increased the miss numbers. However, no significant effect was observed on reaction times. Furthermore, tone level and task difficulty significantly increased activity of the θ and ß bands and decreased activity of the α band. Conclusion. Task difficulty and tone level could significantly affect the parameters of performance and the activity of EEG bands. Therefore, noise control can help sustain appropriate performance.

A Bayesian network based study on determining the relationship between job stress and safety climate factors in occurrence of accidents.

BACKGROUND: Job stress and safety climate have been recognized as two crucial factors that can increase the risk of occupational accidents. This study was performed to determine the relationship between job stress and safety climate factors in the occurrence of accidents using the Bayesian network model. METHODS: This cross-sectional study was performed on 1530 male workers of Asaluyeh petrochemical company in Iran. The participants were asked to complete the questionnaires, including demographical information and accident history questionnaire, NIOSH generic job stress questionnaire, and Nordic safety climate questionnaire. Also, work experience and the accident history data were inquired from the petrochemical health unit. Finally, the relationships between the variables were investigated using the Bayesian network model. RESULTS: A high job stress condition could decrease the high safety climate from 53 to 37% and increase the accident occurrence from 72 to 94%. Moreover, a low safety climate condition could increase the accident occurrence from 72 to 93%. Also, the concurrent high job stress and low safety climate could raise the accident occurrence from 72 to 93%. Among the associations between the job stress factor and safety climate dimensions, the job stress and worker's safety priority and risk non-acceptance (0.19) had the highest mean influence value. CONCLUSION: The adverse effect of high job stress conditions on accident occurrence is twofold. It can directly increase the accident occurrence probability and in another way, it can indirectly increase the accident occurrence probability by causing the safety climate to go to a lower level.

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.