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Abstract Crystalline silica has emerged as a prominent occupational toxicant over extended periods, leading to the development of lung disease and cancer. The objective of this investigation is to establish a benchmark dose (BMD) for crystalline silica micro and nanoparticles based on the dehydrogenase activity of the A549 lung-cell line. The impact of exposure to crystalline silica micro-particles (C–SiO2 MPs) and crystalline silica nanoparticles (C–SiO2 NPs) on A549 epithelial lung cells was examined for durations of 24 and 72 h to evaluate cell viability using the MTT (3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide) assay. The determination of dose-response and BMD was carried out through the BMD software v 3.2. The findings reveal a dose-dependent relationship between cell viability and both C–SiO2 MPs and -NPs. The BMDL values for 24 h treatment of C–SiO2 MPs and -NPs were determined to be 2.26 and 0.97 µg/ml, respectively, based on exponential models. Correspondingly, these values were found to be 1.17 and 0.85 µg/ml for the 72 h treatment. This investigation underscores the significance of particle size as a contributing factor in assessing occupational health risks. Moreover, the utilization of BMDL can facilitate the determination of more precise values for occupational exposures by considering various parameters associated with particle presence.

Introduction: Obesity and overweight are major global health challenges. One of the bad effects of noise that has been recently expressed is the effect of noise on obesity. This study aimed to investigate the effect of high-frequency noise exposure on obesity, food intake, and abdominal visceral fat in adult male guinea pigs. Material and Methods: The animals in this study were 24 adult male guinea pigs randomly divided into 3 groups (control and two case groups). Each case group was separately exposed to high- frequency white noise with sound pressure levels in 65 dB and 85 dB for 5 days per week in 30 days. The food intake was measured daily. The weight of animals was measured at the start and on days 6, 12, 18, 24, and at the end of exposure period. The abdominal visceral fat was extracted and weighted at the end of the study period. The data were assessed using SPSS V.22 software. Results: ANOVA analysis showed that exposure to high-frequency noise at 65dB and 85dB had a significant effect on weight gain, food intake, and abdominal visceral fat weight (P-value< 0.05) which in the group exposed to the noise with 65 dB was more than other groups. Conclusion: Based on this study, exposure to high-frequency noise may be an effective factor in obesity and increasing abdominal visceral fat. Further studies are needed to investigate the mechanism affecting weight status following noise exposure.

Background and Objective: Individuals constantly hear different sounds that can affect their work and living place. The present study aimed at investigating the effect of traffic noise on cortisol and salivary alpha-amylase biomarkers. Materials and Methods: The subjects were men aged 18 to 35 who performed driving activities for one hour in the laboratory. The tests were performed in two conditions of background noise (35 dBA) and traffic noise with a level of 75 dBA and saliva samples were collected from the subjects before and after driving. Finally, saliva samples were analyzed with cortisol and alpha-amylase kits and by ELISA method. The statistical method used for data analysis was SPSS software (version 24) and data analysis was performed by Wilcoxon statistical test. Results: The results of this study indicated that the concentrations of both biomarkers cortisol and alpha-amylase in background noise conditions after driving were higher than that before the start, although this increase was not significant (p> 0.05). In the presence of traffic noise with a level of 75 dBA, the concentration of both biomarkers after driving was significantly higher than that before driving. (p

Introduction: light intensity and duration are physical factors that affect hormone secretion and circadian rhythms. This study aimed to determine the effects of various light intensities on serum melatonin and cortisol levels. Materials and methods: This experimental study was carried out on 32 male rats: Group 1 as the control group, received a brightness of 150 lux, and groups 2, 3, and 4 as the exposure groups received light intensities of 300, 5000, and 8000 lux for 14 days, respectively. To evaluate hormone levels, blood samples were taken on before and after 7 and 14 days of exposure. Then cortisol and melatonin levels were determined by ELISA. Data were analyzed using SPSS. Results: The results showed that cortisol levels after seven days of exposure in the groups exposed to the light intensity of 300, 5000, and 8000 lux increased significantly compared to the control group, and after 14 days, the level of cortisol in the groups. Exposure to a light intensity of 5000 and 8000 lux increased significantly compared to the control. Also, melatonin levels in the group of rats exposed to the light intensity of 5000 lux and 8000 lux after 7 and 14 days of exposure compared to the control significantly decreased. Conclusion: Increased light intensity is associated with increased melatonin suppression and cortisol levels. It is suggested that more studies be done to prove the effect of different light intensities on changes in the levels of these hormones at varying hours of the day.

Background and Objective: Humans, roads, vehicles, and environmental factors mainly cause traffic collisions. Personality form human behavior which is one of the basic parameters in the factor of humans. The present study aimed to investigate the effect of personality on driving errors using a driving simulator. Materials and Methods: The study was conducted on 80 drivers between the ages of 20 and 40. Pride car simulator and the variables of transverse deviation, acceleration, and collision were used to investigate driving errors. Individual personality traits were also determined by the Big Five Factor Questionnaire of Goldberg. Data were analyzed using SPSS software. Results: The results indicated that the personality factors of neuroticism, extraversion, and openness were directly and significantly related to the variables of collision, speed, and transverse deviation of the vehicle (P0.05). Conclusion: The results of the study revealed that some personality factors are correlated with driving errors. Driving is a common daily activity that requires dynamic information processing which varies in different individuals leading to changes in driving errors.

Introduction: Musculoskeletal injuries are one of the most common causes of work-related illnes, reimbursement and absence among workers in working environments throughout the world. Among various factors, exposure to vibration is one of the main causes of these injuries. The aim of this study was to investigate the effect of key factors on the occurrence and exacerbation of the effects of exposure of hand - arm to vibration. Materials and Methods: In this study, the amount of vibration as well as the amount of grasp force for 57 workers working with pneumatic torque wrench in an automobile industry was measured. Results: The main findings of the study showed that the mean grasp force of the workers after exposure to vibration decreased from 43.22 to 40.90 kg. The results of this study can provide valuable information on designing tools, controlling the incidence and outbreak of vibrational disorders. Conclusion: Based on the results obtained in this study, an average of 5.67% reduction was observed in grasp force. Moreover, due to the strong correlation between the mean grasp force difference of workers before and after exposure to vibration and a 4-hour acceleration in the X axis, it can be concluded that the critical axis of the hand-arm vibration is in the X-axis in the pneumatic torque wrench.

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

Background and Objective: Due to major constraints on time, implementation, and funding in every industry, one of the essential strategies for the management of noise control and selection of the best method is to prioritize noise control methods. The present study aimed to prioritize noise control methods in a battery factory using the Analytical Hierarchy Process (AHP). Materials and Methods: The present study was conducted based on a descriptive-analytical cross-sectional design. After measurement of sound pressure level and identification of the main sources of noise pollution, Content Validity Index (CVI) and Content Validity Ratio (CVR) were used for screening the criteria and methods of noise control. The relative weight of each of them was calculated by two factors of Eigenvalue and Eigenvector to prioritize noise control methods based on the study criteria. Results: Based on the results, the Inconsistency Ratio (IR) in pairwise comparisons in all cases was less than 10%, and the consistency of the answers was confirmed. Moreover, among the study criteria, the acoustic efficiency of method with weight (0.1810), and among the proposed methods for noise control, the method of controlling the time of exposure to noise and training of workers with weight (0.1732) had the highest priority. Conclusion: As evidenced by the obtained results, the best criterion for selecting a sound control device is the acoustic efficiency of the method. Furthermore, based on the results, controlling the duration of exposure to noise and training workers in conditions of high noise exposure was the best method to control noise in a battery factory.

Objective: Environmental stressors such as physical and chemical factors can have a destructive testicular function. The present study aimed to determine the effect of concomitant exposure to lead and noise on testicular tissue in male rats. Materials and methods: Twenty male Wistar rats (250-300 g, 12-13wk) were divided into four groups (n=5/each): 1) Control group, 2) Lead group treated with 4 mg/kg lead acetate by gavage for 30 days, 3) Noise group exposed to 4 kHz octave band at 105 dBA for eight hrs./ day for 30 days, and 4) the exposed group to lead plus noise concurrently. The testes' weight was measured, and testes abnormalities were assessed after staining with Hematoxylin and Eosin. Results: The results showed that the weight of testes in experimental groups was significantly decreased compared with the control group (p

Background and Aims: Absent-mindedness of drivers is one of the important cause of traffic crashes. Nowadays using of mobile phones during driving have been spread increasingly and this can disturb the attention of drivers and affect the driving performances. This study aimed to determine the effect of reading and texting of message on driving performance and mental workload of young drivers. Methods: 40 young drivers (20 males & 20 females) with the average age of 25 years were studied in a driving simulator. The scenario was driving in middle line of a three-lined highway and responsions to visual stimulus of a Peripheral Detection Task. Drivers were obligated to drive in this highway with two conditions, one in usual condition and one in condition that they were busy with receiving, reading and texting the short messages. The lateral deviation of vehicle and PDT reaction time were used to record the driving performances. And the Integrated Workload Scale was used at the end of each trial for measuring of mental workload. Results: The average amount of lateral deviation of vehicle. Reaction time and IWS were 26.68 cm, 502.13 ms and 2.02 respectively in usual driving trial, And were 53.04 cm, 652.12 ms and 6 respectively in driving trial with reading and texting the messages. The difference amounts of lateral deviation of vehicle, reaction time and IWS variables were statistically significant (P-value=0.000) based on paired-samples t test and Wilcoxon test in usual and with reading-texting driving trials. Moreover no statistically significant differences were seen in amounts of lateral deviation, reaction time and IWS between males and females. Conclusion: This study showed that the reading and texting the short message during driving can cause both significant decrease of driving performances and increase of mental workload. Accordingly more attention to consequences of using mobile phone during driving is necessary.

BACKGROUND AND OBJECTIVE: Holding the classes in the first weeks of the official semester is one of the main problems for the university education system. This study aimed to determine assessing the causes of students' irregularities in class formation at the beginning of each semester in medical sciences universities. METHODS: This cross-sectional study was conducted at three universities of Babol, Shahid Beheshti and Iran University of Medical Sciences, on two groups of students, those who attended the first classes of semester and those who missed the classes; available sampling method was used to select participants. The researcher-made questionnaires were used to collect data, including students' personal and educational information, students' viewpoints on the reasons for absenteeism during the first classes of the semester, questions about their familiarity with absenteeism codes and regulations, and their viewpoints on canceling classes at the first days of semester. FINDINGS:The viewpoints of two groups of present and absent students (218 and 130 students, respectively) at classes on the first week of the semester, were analyzed using scores 1-5 in the Likert scale, and indicated that the main reason for the students attending at their first classes of the semester was the importance of specialized courses (4.16±0.94) and teachers’ emphasis (4.13±0.96). The most important factors for the students' absence were their experience of canceling first classes of previous semester (3.51±0.95) and students not paying attention to timely attend the first sessions (3.22±1.01). T-test showed that there was a significant direct relationship between students' age and their timely attendance at the beginning of the semester (p=0.035). CONCLUSION: The presence or absence of students at classes on first days of new semester is influenced by various factors and actions taken by influential individuals such as educational staff and faculty members.

Background and Objectives: Nearly 16,000 people are killed in driving accidents in Iran each year. The purpose of this study was, therefore, to determine the effect of age on driving performance, using a driving simulator. Methods: This cross-sectional study was carried out on 16 young drivers, 16 middle-aged drivers, and 16 elderly drivers in Tehran. Driving simulators were used to check the drivers' performances. The main scenario was driving on a freeway at an average speed of 50 km/h, when pedestrians suddenly appeared at a distance of 40 m and the drivers had to brake immediately after noticing the pedestrian. The time interval between the emergence of the pedestrian and stepping on the brake pedal was continuously recorded as the reaction time and the amount of vehicle deviation from the center of the road as the lateral deviation of the vehicle. The drivers' mental workload was recorded after the simulated driving test, using the verbal online subjective opinion scale. Results: The elderly drivers had the highest mean reaction time, 963.8 ms, and there was no significant difference between the mean reaction time for youth and middle-aged drivers (858.3 ms vs. 860 ms). Elderly drivers showed high lateral deviation, 0.69 m, and mental workload, 6.19, whereas youth drivers had the lowest lateral deviation (0.55 m) and mental workload (3.60). MANOVA revealed a significant effect of age (Pillai's trace, V = 0.55, P < 0.001). Univariate ANOVA showed that age significantly affected the lateral deviation (P < 0.001) and mental workload (P < 0.001), but reaction time wa not age dependent (P = 0.101). Poisson regression revealed no significant effect for age on the number of collisions (P = 0.357). Conclusion: Based on the variables under study, driving performance of the elderly group was poor as compared to that of the middle-aged and young ones. Old drivers were subjected to greater mental workload when responding to the stimulus of the driving environment.

There are several risk factors in dentistry that among them repetitive movements, being in a position for a long time due to muscle imbalances, and work-related musculoskeletal disorders which can cause problems such as limited mobility, fatigue, job loss or even changing jobs. Muscle imbalance between the stabilizers and mobilizers of the neck and shoulders in dentists leads to increased work-related disorders, superficial muscle fatigue, and deep muscle atrophy, which in turn, leads to many health problems such as neck pain and disability. To prevent such disorders, a high endurance of the cervical stabilizer muscles is essential for repetitive movements in the distal and shoulder region. In this study, the exercise program, including postural exercises, simultaneous training of shoulder-neck, scapular movements, and co-contraction were designed for 48 dentists. The statistical analysis showed that there was a significant decrease in the median frequency slope of the middle deltoid muscle (p = 0.004) and for the group who received the proprioception training along with posture correction exercises and exercise therapy (p = 0.004). Neck pain increased in the control group who received no exercises, after six weeks (p = 0.165). Six weeks of corrective exercises with ergonomic intervention balance muscles activity and can be used to decrease musculoskeletal disorders and muscle fatigue in person with Non-Specific Chronic Neck Pain.

Objective: Due to the growing use of communication instruments such as cell phones and wireless devices, there is growing public concern about possible harmful effects, especially in sensitive groups such as pregnant women. This study aimed to investigate the oxidative stress induced by exposure to 900 MHz mobile phone radiation and the effect of vitamin C intake on reducing possible changes in pregnant mice. Materials and methods: Twenty-one pregnant mice were divided into three groups (control, mobile radiation-exposed, and mobile radiation plus with vitamin C intake co-exposed (200 mg /kg)). The mice in exposure groups were exposed to 900 MHz, 2 watts, and a power density of 0.045 μw /cm2 mobile radiation for eight hours/day for ten consecutive days. After five days of rest, MDA (Malondialdehyde), 8-OHdG (8-hydroxy-2' -deoxyguanosine), and TAC (Total Antioxidant Capacity) levels were measured in the blood of animals. The results were analyzed by SPSS.22.0 software. Results: The results showed that exposure to mobile radiation increased MDA (P=0.002), and 8-OHdG (P=0.001) significantly and decreased Total Antioxidant Capacity in the exposed groups (P=0.001). Taking vitamin C inhibited the significant increase in MDA and 8-OHdG levels in exposed groups. Conclusion: Although exposure to mobile radiation can cause oxidative stress in the blood of pregnant mice, vitamin C as an antioxidant can prevent it.

Background and Objective: Heat stress is one of the major safety and health concern in the oil and gas industry. The main purpose of this study was to compare the heat stress of oil terminals in northern and southern Iran. In addition, two physiological parameters were utilized in order to validate these indices. Materials and Methods: This descriptive-analytical study was performed on 130 employees working at two oil terminals in Iran (i.e., Kharg and Neka). Initially, heat stress indices including Hang Seng Index (HIS), Allow Exposure Time (AET), WetBulb Globe Temperature (WBGT), and Predicted Four Hour Sweat Rate (P4SR) were measured in this study. Subsequently, the oral and tympanic temperature of the participants were taken in order to validate the mentioned indices using Pearson correlation test. The data were analyzed in SPSS software (version 22). Results: The results showed a significant correlation between the heat stress indices of the indoor workplace in Kharg, Iran, and physiological parameters (P 0.05). Conclusion: According to the results, WBGT and AET are valid indices to assess heat stress in oil terminals. In addition, it was revealed that the heat stress in indoor workplace in Kharg oil terminal was higher than that in Neka oil terminal.

Background: Undoubtedly, lack of good quality sleep is a major problem for students, affecting their educational success causing them academic failure. Therefore, this study is carried out aiming to determine sleep quality and its relation with educational status of Iran University of Medical Sciences students. Methods: This study is a sectional-analytic one performed on dormitory and non-dormitory students of Iran University of Medical Sciences. The criteria of entering the study include being student for at least one yea­r, non-affliction to special diseases and not using drugs and tobacco. People were selected in proportional stratified sampling method after determining the sample volume (400), and Petersburg sleep quality questionnaires were distributed among them. After completion of the questionnaires, their data were extracted and introduced into SPSS version 21. The data obtained via T statistical tests for which Pearson correlation was analyzed were independent. Results: The sleep quality mark was higher than 5 for majority of the students including the dormitory and non-dormitory ones; expressing weak sleep quality. Sleep quality was 7.36 for dormitory students and 7.97 for non-dormitory ones; expressing significant statistical difference (p=0.018). The results suggest that educational status of non-dormitory students (0.22) is better than the dormitory ones (-1.23), and the difference is statistically significant (p=0.000). moreover, the results suggest that there is no relation between good sleep quality and educational status of the students (p=0.232). Conclusion: The study results suggest that sleep quality is not related to educational status. Considering that educational status is a complex matter and is affected by multiple factors including: intelligence, motivation and hard work, sleep quality plays less significant role regarding educational status.

Introduction: Noise is an environmental stressor and can cause or exacerbate mental disorders, and affect the individual performance in certain conditions. This study aimed to evaluate the combined effects of noise and smoking on the cognitive performance of the workers in the automotive industry. Methods: This research is a descriptive-analytical study with a cross-sectional design conducted on 300 workers randomly assigned into two groups of noise-exposed and nonexposed. They were examined using computerized tests, including the Tower of London test (TOL), Continuous Performance test (CPT), and Stroop test. The sound pressure levels were measured based on an 8-hour equal-loudness contour in each group according to ISO 9612 standard, using the Testo CEL-815 sound level meter. Results: The study of combined effects of noise and smoking on 12 CPT indicators using the 2-way Analysis of Variance (ANOVA) indicate that noise and smoking factors had a significant impact on the mean number of errors and correct responses in the third 50-stimuli stage, the mean number of errors and correct responses in the second 50-stimuli stage with P

Background: Lead is a major environmental pollutant and can adversely affect humans and animals. There are conflicting data about the ototoxic effect of lead. This study experimentally examined the association between blood lead levels (BLL) and the subsequent hearing impairment in male rats. Methods: Twenty-two male rats were randomly categorized into experimental (exposed to lead acetate, 4 mg/kg by gavage) and control groups. We evaluated the groups by click and tone audiometric burst tests, comparing the data before and 30 days after exposure to lead acetate (4mg/kg). Also, blood samples were collected from the rats and analyzed for lead levels by graphite furnace atomic absorption spectrometry. Results: The study findings demonstrated remarkable increase in hearing threshold in the lead-exposed group, compared to the controls (p

Introduction: In many countries, the noise has been ranked among the important risk factors in the printing industries. The purpose of this study is to design a tool for Assessing the level of knowledge, attitude and practice of the printing industry workers in the field of hearing protection and determining its validity and reliability. Methods: To design a questionnaire, 35 questions were prepared at first. To evaluate the validity, content validity methods and to evaluate the reliability of the instrument, Cronbach's alpha coefficients and Test retest methods were used. The data were analyzed using SPSS-20 software. Results: The results showed that 10 items in terms of content validity were below the standard and should be deleted from questionnaire. Also, in the reliability analysis of the questionnaire, Cronbach's alpha coefficient for all four parts of knowledge, attitude, risk perception and practice was 0.884, 0.719, 0.832 and 0.727 respectively. The Spearman correlation coefficient with the results of 0.810, 0.861, 0.890 and 0.985 and Pearson correlation coefficient with the results of 0.912, 0.964, 0.866 and 0.991 respectively for knowledge, Attitude, risk perception and practice were used to analyze the Test retest method of the questionnaire. Conclusion: Designing this questionnaire to examine the knowledge, attitude and practice of printing industry workers about hearing protection can examine possible solutions to reduce the harmful effects of the noise on employed workers, which should be tested on a wider scale.

Background and aims: Road traffic accident annually lead to the death of 1.2 million people and also the disability of some 50 million people in the world. Iran is one of the countries with the highest rates of road accidents in the world. According to the annual statistics by the Iranian Legal Medicine Organization, 15,932 people have lost their lives in road traffic accidents in 1395 sh. According to figures in this report, over 75% of road deaths occur among men. Driving and guiding a vehicle is required to assign different levels of attention. In this regard, also can be pointed to the role of the mental workload. Mental workload known as a requirement that a duty impose on the available mental and cognitive resources of people. Mental workload is too high or too low can lead to incomplete understanding, inadequate attention and information processing to be inappropriate. A variety of factors can be effect on individuals driving performance and their mental workload such as age, gender, driving character and fatigue. According to studies, mistakes that can lead to accidents, in many cases, are the result of high mental workloads. Measurement of mental workload while driving can reflect the cognitive needs imposed on the driver. Various behavioral, self-reporting and physiological methods have been successfully used so far in order to measure the mental workload. One of the best ways to measure the mental workload is the evaluation of the individualschr('39') reaction time. Reaction time is the time interval between the emergence of a stimulus and the individualchr('39')s response. Driver’s gender is one of the possible effective factors that can affect driving performance. This study aimed to assess the effect of gender on young driverschr('39') mental workload and driving performances using a driving simulator. Methods: This cross-sectional study was conducted on 40 young drivers (20-29 years) including 20 women and 20 men in Tehran at 2017. The inclusion criteria for the study were aged 20 to 29 years, filling informed consent to participate in the study, sleeping enough for 8 hours at night before the test, having at least two years of driving experience, driving at least once In the week, lack of driving experience with the driving simulator, having adequate or improved vision for the eyes, or for each eye, did not use psychotropic drugs. Exclusion criteria were included the request of the participants to leave the study, having signs of discomfort caused by the simulator, expressing a physical discomfort after the start of the test for any reason. The driving simulator used in this study is a half-body Pride made by the specialists of the virtual reality group of Khajeh Nasir Tusi Industrial University. The simulator has a computer and graphics card and software tools for simulating intra-city and inter-city roads, freeways, night driving, and driving in snowy, rainy, and foggy conditions. The driverschr('39') performances were evaluated using the PDT reaction time and vehicle lateral deviation variables under two conditions: driving with and without mental calculations. The PDT reaction time test is one of the most common and suitable methods for assessing the performance of drivers and the response time of mental workload in simulator studies. Its validity and reliability have been confirmed in various studies. The Rating Scale Mental Effort (RSME) and the Integrated Workload Scale (IWS) self-report scales were used to estimate the individualschr('39') workload. The main scenario of the study included driving a distance of 20 km on a highway. Results: The mean lateral deviation obtained for female and male drivers was 0.55 and 0.51 m respectively, in the driving phase without mental calculations. Moreover in this phase the mean reaction time was 482 ms for females and 450 ms for males. In the driving phase with mental calculation, the mean lateral deviation obtained for female and male drivers was 0.67 and 0.62 m and mean reaction time for females and males was 606 ms and 569 ms, respectively. Based on the RSME and the IWS scales, women perceived more mental workload than men. For most variables of the study, however, the difference between male and female values was not significant based on the independent t-test (P-value> 0.05). Also, performing mental calculations while driving caused a significant increase (P-value = 0.05) in the values of the vehiclechr('39')s lateral deviation, the driverschr('39') reaction time, and the RSME and the IWS scales. Conclusions: Although there were no statistically significant differences in the study variables between males and females; the mean value of the lateral deviation for women was slightly higher than men, and their driving performance was slightly weaker than men. More lateral deviation of the vehicle should be considered in the process of doing mental calculation, because the high lateral deflection, especially automotive deviation to the left can be dangerous and even fatal accidents.

Background and aims: Speeding and deviation to the left and right are the most notable and important causes of injuries that caused by traffic accidents in most countries. Injuries caused by these events are so great that it will be remembered as a war on the road. Due to the importance of the relation between aggression, errors and violations, this study aimed to investigate the relationship of aggressive driving and the average of driving speed and lane deviations. Methods: in the present study, 75 taxi drivers completed the Spielberger State-Trait Anger Inventory. Assessing the dimensions of aggression performed by car driving simulator. Using SPSS (V:22) ,descriptive tables and Spearman correlation coefficient data were analyzed. Results: The findings showed that there was a significant direct relation between all aspects of aggression and the average and maximum of speeding and lane deviations, So that aggressive drivers drove with high speeds and were more willing to shift to the left and right. Conclusion: Aggression is considered as one of the important factor affecting to increase the average speed and lane deviations.

The public concern of harmful effects of radiofrequency radiation exposure, especially with rapid increase in the use of wireless and telecommunication devices, is increasing. Some studies show fetal and developmental abnormalities as the result of radiofrequency radiation exposure. We aimed to investigate possible teratogenic effects of radiofrequency in 915 MHz on mice fetus and protective role of vitamin C. 21 pregnant mice were divided into 3 groups. Control group was in normal condition without any stressor agent. Exposure group was exposed to 915 MHz RFR (8 h/day for 10 days) and 0.045 µw/cm2 power density. The exposure plus vitamin C group received 200 mg/kg vitamin C by gavage and was exposed to 915 MHz RFR (8 h/day for 10 days) and 0.045 µw/cm2 power density. The fetus weight, C-R length were measured by digital balance and caliper. Tissues were assessed after staining with H & E. Our results showed significant increase in fetus weight and C-R length and also enlarged liver, tail deformation in mice fetus in exposure group. Although usage of vitamin C caused significant decrease in mentioned parameters. The outcome of this study confirms the effects of radiofrequency radiation on growth parameters such as body weight, length and some tissues in mice fetuses and protective effect of vitamin C. However more studies on non-ionization radiation in different frequencies and severity, during pregnancy are needed to clarify the exact mechanisms of these changes and better protection. Keywords: Radiofrequency radiation, Mice fetus tissues, Vitamin C, Fetal and developmental abnormalities

Introduction: Impairment of alertness, attention and performance associated with sleepiness and fatigue in nurses occur in night and long-term shifts that in the end of night shift reach to the maximum level can lead to traffic accidents when they returning home. The purpose of this study was to determine the effect of night shift on psychomotor abilities of driving in nurses after shiftwork. Material and Method: A cohort study was carried out on 23 night shift and 24 day shift female nurses aged 20 to 40 at Sina Hospital in Tehran city, using the Vienna Test System (VTS). The concentration and selective attention, reaction time, pheriperal perception, and coordination before and after night and day shifts were measured. A multiple linear regression model and Backward stepwise selection method was used for analyses. Result: In the concentration and selective attention test, sum hits (p = 0.038) and in the visual perception test , divided attention (p =0.006) and visual field (p =0.019), and in the reaction time test the mean motor time (p =0.034) showed a significant adverse relationship with working in night shift, but the visomotor coordination variables did not show any significant correlation. Conclusion: The results showed that the concentration and selective attention, peripheral perception, and reaction time of psychomotor ability of driving were significantly adversely impaired in nurses after night shift. These results in evidence of the mechanism of increasing traffic accidents after night shift among nurses added to the previous studies in this subject.

Background and aim: Driving after a night shift imposes a risk on health care professionals and other road users. The aim of this study was to measure psychomotor performance of driving of night shift nurses compared to day-shift nurses. Methods: Forty-seven volunteer female nurses working at Sina hospital in Tehran, Iran, with a call in all departments of hospital, participated in this study (23 night shift and 24 day shift nurses) in 2016. The tests included RT for simple reaction time, ATAVT for perceptual speed, LVT for visual orientation and ZBA for time anticipation. Data collection tools were individual characteristics, 11-item circadian type inventory (CTI), Stanford sleepiness scale (SSS), and Swedish occupational fatigue inventory (SOFI-20) questionnaires. Psychomotor driving performance was assessed using validated computerized traffic psychological battery of Vienna Test System (VTS), before and after the shifts. Data analysis was performed using paired-samples t-test and Linear Regression. Results: The mean age of day and night-shift nurses were 31.4±5.6 and 28.7±3.9 years respectively, no significant difference between two groups. Thirty percent of night shift and 16.7% of day shift nurses reported traffic accidents in the past year. The results revealed that, scores based on viewing times in visual orientation test (p=0.005), and median reaction time score in choice reaction time and reactive stress tolerance test (p=0.045), had a significant association with a 12-hour night shift with a 3-hour nap. Conclusions: Twelve-hour night shift work impairs choice reaction time and visual orientation in nurses, even though they take a 3- hour nap during the shift. These skills are required for safe driving.

Introduction: Irregularity or delay in the beginning of classes at each semester, due to absence of students and/or professors, is a common problem in most Iranian universities. This study aimed to investigate the reason for irregularities at the beginning of each semester according to the viewpoints of educational experts. Method: This cross-sectional study was carried out at three universities of medical sciences namely; Babol University of Medical Sciences, Shahid Beheshti University of Medical Sciences, and Iran University of Medical Sciences in the first academic semester of 2015-2016. This study investigated the viewpoints of educational experts working in four schools of medicine, dentistry, paramedicine, and public health using a researcher-made instrument. The instrument’s face validity was surveyed and confirmed by six faculty members and its reliability was tested by test-retest method (r=0.82). Descriptive statistics were used for data analysis. Results: According to a forty-two member panel of educational experts’ opinions, the main reasons for academic irregularities at the beginning of each semester is students’ absence followed by weak disciplinary rules, lack of implementation of regulations, teachers’ reluctance to hold classes on time, as well as not completing roll calls and not passing them to the registrar’s office. Conclusion: From the educational experts’ point of view, the factors related to students and teachers have greater effect on the recession of classes at the beginning of each academic semester. Therefore, a better planning for semesters and more control by authorities are required.

Introduction: One of the possible effects of occupational exposure to high noise is high blood pressure and cardiovascular disease. Aim of this study was to investigate the association between noise with blood pressure and heart rate in an automotive industry. Methods: 78 male workers who worked in an automobile factory, were participated. Blood pressure and heart rate were measured in the morning and in the middle of the day. All measurements were performed at three noise levels: 85-95, 75-85 and 65-75 dB. All data were analyzed using SPSS and MATLAB. Results: Post Hoc test showed that noise has the same effect on the average systolic and diastolic blood pressure (p= 0.733) but Box-whisker plot showed that after exposure, the variation range of blood pressure and heart rate are much more than the other groups. However, this project didn’t show any a specific correlation between the increase in noise level with heart rate but variance analysis showed that the noise level increase lead to changes in heart rate (p= 0.049). Conclusions: Noise level in 75-85dB as same as 85-95 dB caused the changes in blood pressure and heart rate. Due to cardiovascular disease, it is recommended training programs for workers, reduced noise level and periodic monitoring of blood pressure of workers, especially with a history of hypertension.

Introduction: driving is such a complex cognitive task that requires a high level of vigilance and response to an emergency. Anything that leads to cognitive performance degradation in the driverchr('39')s mental processing, increases crash risks. Traffic noise as one of the most destructive elements of cognitive function was examined in this study. Methods: In this study, the sample consisted of 80 patients (40 cases and 40 controls) who were students of Tehran University of medical sciences that were selected through systematic sampling and then the average sound pressure level recorded traffic noise was played for participants in the acoustics room. To Measure reaction time and error in time movement anticipation, the RT and ZBA softwares were used ,respectively. Results: The results revealed that reaction time increased significantly after exposure to traffic noise. The error time movement after exposure to traffic noise has not significant difference. Conlusions: According to the results it can be concluded that mental activities such as speed and power of information processing are affected by traffic noise and in a confrontation with traffic noise show different changes.

Mental workload is an important issue in occupational health. This study aimed to determine the validity and reliability of the Rating Scale Mental Effort (RSME), Integrated Workload Scale (IWS), and Overall Workload Scale (OW) in Iran. This study was conducted on 100 male students of Iran University of Medical Sciences. The forward-backward translation method was used to evaluate the linguistic validity of the scales. Then the scales were presented to six ergonomics and occupational health experts to assess the content validity of the scales. Internal validity of the scales was assessed by correlating mental workload scale scores with reaction times on a criterion task. Finally, multiple sessions of a hybrid memory-search task were performed to determine the reliability of the scales. There was prefect agreement among the experts regarding of all three scales. Content Validity Index and Content Validity Ratio were 1 for each three scales. About the reliability of the scales, the Pearson correlation coefficients between the scale scores in the test and retest phases were 96, 88, and 84 for RSME, IWS, and OW, respectively. Finally, Validity and reliability of the scales were approved and It seems that these scales can be used for measuring self-reported mental workload.

Introduction: High mental workload is one of the important factors that results in errors in safety and occupational health scope and its measurement has high importance. So, this study aimed to determine validity and reliability of Verbal Online Subjective Opinion (VOSO) and Modified Cooper-Harper (MCH) scales in measuring mental workload. Methods: This study was conducted on 90 male students of Iran University of Medical Sciences. In this study, the Forward-Backward translation was used for translation of scales. Moreover, Content Validity Ratio (CVR) and Content Validity Index (CVI) were calculated by having suggestion of 6 Ergonomics and Occupational health experts. The Hybrid Memory Search Task software was used to create mental workload. Convergent validity of scales was calculated using correlation of scales with reaction time and then Test-Retest method was used to determine the reliability of scales. Results: Content and convergent validity of scales were confirmed and correlation of both scales with reaction time were higher than 0.8. Moreover for determination of scales reliabilities, Pearson correlation coefficient between scales values in test and retest trials were 0.86 and 0.91 for VOSO and MCH respectively. Conclusion: It seems that in regard to confirmation of validity and reliability of VOSO and MCH in this study and their high correlation with reaction time, it can use these scales in measurement of mental workload.

Introduction: Occupational noise is among the most critical occupational hazards, which, in addition to hearing loss, can cause other adverse consequences on an individual’s physical and mental health. Long-term exposure to noise can affect blood and biochemical parameters and subsequently lead to increased risk of cardiovascular disease. This study investigated the effect of occupational exposure to noise on blood and biochemical parameters of workers in an insulator manufacturing plant. Methods: This case-control study was conducted on workers in the production section (49 people as a case group) and the administrative staff (10 people as a control group) in one insulator manufacturing plant from 2010 to 2014. To assess individual exposure of workers to noise, the noise dosimeter model TES-1355 was used. Noise dosimetry testing was done based on the exposure pattern of workers to noise in compliance with the Iranian national standard (the criterion level of 85 dBA and the exchange rate of Q = 3 dBA). Blood parameters such as blood glucose, cholesterol, red blood cells (RBC), white blood cells (WBC), hemoglobin (Hb), and hematocrit (Hct) were studied in production workers (case) and administrative staff (control) over five consecutive years. The data were analyzed by software (SPSS-22) using the t-test, Mann-Whitney test, Fisher exact test, and Greenhouse-Geisser test. Results: No significant difference was found among the demographic data of the two groups (p > 0.05). Average of glucose and cholesterol levels in the two groups was statistically significant (p < 0.05) and blood glucose levels in the case group significantly reduced over time and cholesterol increased (p < 0.001). Mean difference of RBC number, WBC number, and serum levels of Hb and Hct was statistically significant between the two groups (p < 0.05). In addition, these hematological parameters increased among workers during these years. Conclusion: Occupational exposure to noise may have a significant effect on an individual’s blood parameters, which will cause harmful effects on worker health. Therefore, industrialists must take preventive measures in the field of noise control.

Traffic violations and aggression are often regarded as social issues with important social and economic consequences. The present study investigated the potential contribution of demographic variables, driving anger, and aggression on the prediction of aggressive driving behaviors. The sample population consisted of 168 male drivers with an age range of 19–30 years old and the average driving experience of 9 years. All participants filled out the self-reported scales that assess driving anger, aggression dimension, and driving behaviors. Based on the participants' responses to the trait-anger dimensions in Spielberger State-Trait Anxiety Inventory, they were re-categorized in three driving anger categories of high-trait-anger, medium-trait-anger, and low-trait-anger. All of the participants had a driving certificate. The results of this research indicate that: (1) for almost all variables, the effect of anger was significant, (2) anger situation had a contribution in the prediction of lapse, errors, and violations, (3) demographic variables, driving anger, and aggression were all involved in a complementary manner in predicting the driving behavior, and (4) aggression was the best predictor of the violations. Future research is recommended to continue to investigate the effect of various environmental, social, psychological, and personality factors on risky driving behaviors in order to identify appropriate treatment and prevention strategies for this societal concern.

زمينه و اهداف: يکي از منابع اصلي آلودگي صوتي وسايل حمل و نقل است که به وجود آورنده آزردگي‌هاي صوتي مي‌باشد. در اين تحقيق ارتباط بين آزردگي صوتي با عوامل دموگرافيک ساکنان در جوار بزرگراه بسيج شمال به جنوب منطقه 15 مورد بررسي قرار گرفت. مواد و روش‌ها: طول منطقه اندازه گيري در جوار بزرگراه بسيج، دو کيلومتر بود که به 10 ايستگاه 200 متري تقسيم گرديد. پارامتر LeqA (تراز معادل مواجهه صوت) در ايستگاه‌ها به مدت 5 دقيقه اندازه گيري شد. جهت بررسي ارتباط بين صدا با آزردگي صوتي افراد ساکن در اتوبان، پرسشنامه‌اي تدوين گرديد. با استفاده از فرمول کوکران حجم نمونه 170 نفر شد که از نظر عوامل دموگرافيک مورد بررسي قرار گرفتند. تمام مراحل مطالعه حاضر با در نظر گرفتن موازين اخلاقي و پژوهشي اجرا گرديد. يافته‌ها: آزردگي صدا در زنها بيشتر از مردها تعيين شد و 91/48 درصد از زنها آزردگي زياد را گزارش کردند. حداقل LeqA برابر dBA 75/9 مربوط به ايستگاه اول و حداکثر LeqA برابر dBA 87/60 مربوط به ايستگاه پنجم بود. همچنين ارتباط معناداري بين آزردگي صوتي با LeqA، جنسيت، اختلال در خواب، سردرد، اختلال در آرامش، اختلال در تمرکز در اثر صداي ترافيک يافت شد (P

Tank fires are rare but carry significant potential risk to life and property. For this reason fire protection of tanks is critical. Fixed Low expansion foam and water spray cooling systems are one of the most effective and economical ways to reduce damages to a tank from fire. Such systems are currently installed in many companies but are not effective enough and require involvement of firefighters which in turn threaten their lives. This paper studies in a systematic way the problems of foam and cooling systems currently installed in a few domestic companies which operate storage tanks with focus on floating and fixed roof atmospheric tanks containing hydrocarbons and offers possible solutions for more efficient installation, design and operation of such systems.

Background: Traffic noise is one of the main important sources in urban noise pollution, which causes various physiological and psychological effects that can cause disturbs in performance, sleep disturbances, hearing loss and impact on job performance. This study was conducted to verify the impact of road traffic noise on reaction time in terms of extraversion and sex. Methods: Traffic noise was measured and recorded in 10 arterial streets in Tehran, and then the rec­orded noise was emitted towards participants in an acoustic room. The participants were 80 (40 cases and 40 controls) students. Personality type was determined by Eysenck Personality Inventory (EPI) questioner. Reaction time before and after exposure to traffic noise was measured. Results: Reaction time before exposure to traffic noise did not differ (P=0.437) significantly between introverts and extraverts. However, it was increased significantly in both groups after exposure to traf­fic noise (P

Hydrocarbon bulk storage tank fires are not very common, but their protection is essential due to severe consequences of such fires. Water spray cooling system is one of the most effective ways to reduce damages to a tank from a fire. Many codes and standards set requirements and recommendations to maximize the efficiency of water spray cooling systems, but these are widely different and still various interpretations and methods are employed to design such systems. This article provides a brief introduction to some possible design methods of cooling systems for protection of storage tanks against external non-contacting fires and introduces a new method namely “Linear Density Method” and compares the results from this method to the “Average Method” which is currently in common practice. The average Method determines the flow rate for each spray nozzle by dividing the total water demand by the number of spray nozzles while the Linear Density Method determines the nozzle flow rate based on the actual flow over the surface to be protected. The configuration of the system includes a one million barrel crude oil floating roof tank to be protected and which is placed one half tank diameter from a similar adjacent tank with a full surface fire. Thermal radiation and hydraulics are modeled using DNV PHAST Version 6.53 and Sunrise PIPENET Version 1.5.0.2722 software respectively. Spray nozzles used in design are manufactured by Angus Fire and PNR Nozzles companies. Schedule 40 carbon steel pipe is used for piping. The results show that the cooling system using the Linear Density Method consumes 3.55% more water than the design using the average method assuming a uniform application rate of 4.1 liters per minute. Despite higher water consumption the design based on Linear Density Method alleviates the problems associated with the Average Method and provides better protection.

Developing technology and using equipment in Iranian industries caused that maintenance system would be more important to use. Using proper management techniques not only increase the performance of production system but also reduce the failures and costs. The aim of this study was to determine the quality of maintenance system and the effects of its components on failures of kilns in two gypsum production companies using Failure Modes and Effects Analysis (FMEA). Furthermore the costs of failures were studied. After the study of gypsum production steps in the factories, FMEA was conducted by the determination of analysis insight, information gathering, making list of kilns’ component and filling up the FMEA’s tables. The effects of failures on production, how to fail, failure rate, failure severity, and control measures were studied. The evaluation of maintenance system was studied by a check list including questions related to system components. The costs of failures were determined by refer in accounting notebooks and interview with the head of accounting department. It was found the total qualities of maintenance system in NO.1 was more than NO.2 but because of lower quality of NO.1’s kiln design, number of failures and their costs were more. In addition it was determined that repair costs in NO.2’s kiln were about one third of NO.1’s. The low severity failures caused the most costs in comparison to the moderate and low ones. The technical characteristics of kilns were appeared to be the most important factors in reducing of failures and costs.

Background and objective: Safety in the oil refining companies is considered as an important issue. These companies consider improving the safety culture as their main priorities. This study aimed to assess the safety culture of an oil refinery with the use of Geller model. Methods: According to Geller model, which is composed of three main dimensions, questionnaire and the Checklists were prepared. After a pilot study and descriptive study and estimating the reliability of checklists and questionnaires, 190 personnel were selected for sample group. There was a performance assessment of the staff’s performance along with the questionnaires filled by staffs. The environmental assessment was completed by checklists. Data from questionnaire and the checklists were transferred to the database. Statistical analysis was performed by using SPSS15 through Chi Square and Pearson Tests. Results: The mean age was 35.46 years with SD=10.68. Most of the personnel under study were married (70.50%) most of them had diploma (62.1%). Based on the view of the staff, 29.5% of them in their work life had a job-related accident. They also had a medium attitude and relatively good performance. Using Pearson test, There was a significant relationship between employees’ perception and their performance (p= 0.009). Conclusion: Although there was a significant relationship between staff perception and performance with kind of employment, work unit, work type, & education, which in most cases due to obeying standard safety rules, had good performance, staff had a weak attitude in relation to applying safety rules. It seems that we need to work on this issue so that safety and applying safety rules become a value at work.

Background and aims: Traditionally in any event, the judgment was usually based on human error and accidents and according to the latest statistics published in Iran the main cause of accidents is unsafe acts and recklessness. The aim of this study was to investigate the factors influencing safety culture in detergents and cleansers units and its role in the incidence of accidents. Methods : In this study aimed to determine the safety culture in detergents and cleaners companies, the standard safety culture questionnaire was extracted and its reliability was determined in selected population as 0.86. After collecting the questionnaires and investigation of the related clinical files the data analysis was performed using SPSS17 software. Results: Data analysis showed that in both selected companies the mean age of personnel, work experience and any incidents occurring during the period of their working in the company were 34.2 ± 6.67, 10.4 ± 5.842 and 0.92 ± 1.957 respectively. While in the first company the safety culture score was180.51, in the second company it was 200.45 that is statistically significantly different (p

Background and aims: One of the innovative technologies for air pollution control is non-thermal plasma. The dielectric barrier discharge reactor is one of the reactors that applied in non thermal plasma technology for air polluation control. In dielectric barrier discharge reactor, the distance between the electrodes for electric discharge is low and led to increasing space velocity of the pollutant in the discharge zone. This increase in the velocity results in a decrease in the probability of collision of the produced active species with pollutant molecules, which consequently decreases the efficiency of pollutant degradation. The aim of this study was to design a new dielectric barrier discharge reactor for increase the dischrge gap zone. Methods: The non-thermal plasma reactor employed in this study was made of quartz as a rectangular cube shape. In this reactor, the expanded graphite was used as the discharge electrode which was poured uniformly in the bottom of the reactor and a copper plate was on the outer surface of the reactor applied to play the role of the earth electrode. Chloroform removal efficiency as a function of flow rate, concentration of pollutants and applied voltage was investigated in this reactor. In addition, it was observed that the exhaust gas from the reactor contains nitrogen oxides, chlorine, hydrochloric acid, phosgene, trichlorobenzaldehyde and trichloroacetaldehyde. Conclusion: Results of the study showed that electrical discharge was created in larger discharge gap which resulted in space velocity decrease of pollutants in this region and caused to increase of chloroform degradation. Moreover, flow rate increase affected lightly on the degradation which is owing to the adsorption property of the expanded graphite as well as an increase in discharge gap region.

Aims: The present study aimed to investigate the relationship between traffic noise and drivers′ reaction time (RT) and their error in estimates of movement time. Materials and Methods: In over all, 80 university students with at least 3 years postlicense experience of driving were divided into two groups including traffic noise exposure and control group. S5 test of Vienna test system package was used for assessment of RT. In addition, time-movement anticipation was employed for measuring the rate of error in estimation of movement time before exposing to the traffic noise. After a 1-month interval, participants in the experimental group were exposed to traffic noise about 2 h and the tests were performed again for both groups. Results: Accordingly, RT was statistically higher after traffic noise exposure for male and female. However, there was no significant difference between time of movement before and after exposure to traffic noise both for male and female (P > 0.05). In addition, no difference was shown between movement time, number of accurate estimates, and number of estimates with gross errors before and after of traffic noise exposure in experimental and control group. Conclusion: The results suggest that traffic noise may be associated with poorer mental processing, which can result in longer RT during driving. Therefore, traffic noise would expose drivers to consequent accidents and incidents.