alireza mortezapour

The importance of surgery and its high workload are not hidden from anyone. So far, various studies have been conducted with the NASA-TLX instrument and other commonly used instruments to measure surgeons’ workload. The present study seeks to investigate the relationship between the mental workload of surgeons and their productivity through the validation of specialized tools for this job in Iranian culture.

After checking the validity and reliability of "SURG-TLX" and productivity tools, they were utilized among 60 surgeons to investigate the relationship between their workload and productivity (WHO-HPQ tool). Content validity indices, Cronbach's alpha coefficient and Spearman's correlation coefficient were used to analyse the results.

Both tools had good validity and reliability in Iranian culture. The results of the relationship between mental workload subscales with different dimensions of productivity showed that some dimensions of mental workload including mental needs (correlation coefficient -0.65 and significance level 0.02), physical needs (correlation coefficient -0.54 and significance level 0.04) and time requirements (correlation coefficient -0.44 and significance level 0.02) had a reverse and significant relationship with the overall productivity score. Despite the reverse relationship between the other dimensions of mental workload and the overall productivity score in surgeons, this relationship was not statistically significant. The results indicated a reverse and significant relationship between some of the mental workload and some of the productivity subscales.

In addition to the possibility of using these tools in the future studies in Iran, due to the direct relationship between workload and productivity in surgeons, measures can be taken to maintain the workload at a standard level and prevent the reduction of their productivity.

The high prevalence and also multiple consequences of addiction to various online content, including online games and social networks, have become a major challenge. The ability to predict musculoskeletal disorders from this addiction can help reveal in students' health status in the near future. The aim of this study was to determine the prevalence of this addiction and the ability to predict neck pain from this matter in students. Study Design: A cross sectional study.

This study was carried out among 665 students. Data collection was performed through three questionnaires on problematic use of online games, social networking addiction, and Nordic musculoskeletal disorders. Data were compared with Chi-square and independent T-test, and the logistic regression model was then presented at a significant level of 0.05. Finally, the area under the receiver operating characteristic (ROC) curve and Discriminant analysis were conducted to clarify associations.

The prevalence of Internet-related content addiction was 32.8%. The results showed that addiction to social networks and online games can increase the risk of neck disorder. Also 0.58 area under ROC curve depicted the ability to predict neck pain from this addiction.

In students with internet - related content addiction, neck disorder can be predicted. Given the high prevalence of internet addiction in students, it is essential to take immediate and appropriate interventions to avoid the associated adverse effects such as neck problems.

Due to the increasing use of chemicals in academic laboratories, a tool to measure awareness of students regarding labeling, hazards and characteristics of chemicals is still needed. The aim of  this study was to design and validate a questionnaire to the assessing student’s knowledge about chemical hazards. The present study was conducted in two stages of design and evaluation of validity and reliability of the questionnaire. The validity of designed questionnaire was evaluated by using Content Validity Ratio (CVR) and Content Validity Index(CVI) coefficients and opinion of 10 subject matter experts. Cronbach's alpha coefficient was calculated to determine the reliability of the questionnaire. The content validity index and Cronbach's alpha coefficient of questionnaire were 0.938 and 0.728 respectively, which are accepted values. Results showed that the reliability and validity of designed questionnaire were acceptable and this tool can be used to measure people awareness for a safe use of chemicals.

Firefighters are exposed to variety of stressors. Job related factors and shift-work system are the main stressors among Iranian firefighters. It seems necessary to study these related factors. Therefore, the present study aimed to find out what dimensions of job stress are associated with 24-hour shift-work schedule of firefighters.

After studying the validity and reliability of Persian version of NIOSH Generic Job Stress Questionnaire, 228 firefighters completed it, together with the validated version of the Survey of Shift-worker (SOS) questionnaire. The Spearman, Chi 2, Mann-Whitney and ANOVA statistical analysis were conducted through SPSS 18.

Results showed that some undesirable effects of Shiftwork in more than 60% of firefighters are medium to high. There was a significant relationship between variables of shiftwork (sleep disorders, the undesirable effects of shiftwork) and the variables of job stress (ambiguity in job future, workload, physical environment, job control, employment opportunities, non-work activities, social support from bosses, spouse, friends, relatives, subjective demands, role incompatibility, role ambiguity and job satisfaction).

The present study shows that adverse effects of 24-Hour Shiftwork and occupational stress largely interact with each other. Therefore, it could be concluded that job stress could be moderated or reduced and job satisfaction could concurrently be increased through focusing on the roots of occupational stress from the perspective of shiftwork systems.

Nearly a third of people work in jobs that use voice to be part of their work. Teachers as the largest group of professional vocal users, are at risk of vocal disorders. The aim of this study was to investigate the effect of different risk factors on vocal disorders in teachers.  

This is a cross-sectional and descriptive-analytic study that was conducted on 73 primary and secondary male and female school teachers in Saveh in 2017 by random sampling. The researcher-made questionnaire on risk factors affecting verbal disorders with the aim of identifying risk factors and a Voice Handicap Index (VHI) questionnaire (30 items) aimed at evaluating verbal disorders and symptom questionnaire were used in this study. All of them have been shown to be valid and reliable in previous studies. Data were analyzed using t-test and chi square statistical tests by SPSS ver.24.

The reliability of the researcher-made questionnaire on the risk factors affecting vocal disorders was confirmed by Cronbach’s alpha (0.736) and its validity was confirmed by the experts regarding the adequacy of the number of questions, the lack of ambiguity and the assessment of content fitness. According to our gathered data, vocal disorders were observed in 55% of the teachers. Also the results showed the rate of vocal disorders in female teachers is far higher than male teachers. Functional disturbance of vocal cords and allergy as general risk factors, teaching tools and poor air quality as environmental risk factors and inadequate vocal rest and job stress as occupational risk factors contributed to increasing vocal disorders in teachers. Among the symptom associated with verbal disorders in teachers, vocal fatigue and hoarseness were more common in comparison with other symptoms.

Due to the prevalence of vocal disorders in half of the teachers and the impact of general, environmental and occupational risk factors, it is necessary to identify and control the risk factors of vocal disorders in teachers. It can also be concluded that teachers can enjoy a healthy voice by considering the principles of ergonomics and occupational health.

One of the most important and the most common health problems among office workers and computer users is the risk of developing musculoskeletal disorders (MSDs). This study aimed at evaluating risk factors of MSDs and determining the effectiveness of the ergonomic, organization, education interventions on reducing MSDs in the office workers of university offices of Tehran, Iran. This quasi-experimental study was conducted on 221 employees during spring 2015 to summer 2016. Participants were categorized to four groups by simple random sampling: control group (n = 55), recipients of education interventions (n = 57), recipients of organization interventions including job enrichment, job enlargement and job rotation (n = 54), and recipients of ergonomics interventions (n = 55). Rapid office strain assessment (ROSA) and Cornell musculoskeletal discomfort questionnaires (CMDQ) were used for data gathering. Data were analyzed by one-way analysis of variance (ANOVA) and paired-samples t-test using the SPSS version 16 software. After the intervention, a significant difference was revealed in the final mean score for ROSA in the two groups of recipients of education and ergonomic interventions (P < 0.05). Also, data revealed a significant difference in MSDs, including neck, shoulders, and hand/wrist, among ergonomics and education groups. Educational and ergonomic interventions may reduce ergonomics risk factors of MSDs and prevalence of discomfort. However, according to the results, organizational interventions alone may not be more effective in reducing risk factors of MSDs and their discomforts. The effectiveness of multilayered interventions should be investigated in the future.

Nowadays, the use of the Internet among students has become widespread. Addiction to virtual networks and online games can have various consequences, including the threat of musculoskeletal system in these people. The purpose of this study was to determine the effect of addiction to social networks and online games on students’ wrist pain. This study was conducted among 665 students. Data collection was done through three questionnaires of problematic use of online games, social networking addiction and Nordic musculoskeletal disorders. Data were compared by Chi-square and independent T-test and finally, logistic regression model was presented at a significant level of 0.05. The results showed that social network and online game addiction can increase the risk of pain in the wrists. Sex had a significant impact in the effect of social network addiction on pain in the wrist. Other results of the present study are the not significant differences in the age and level of education of the participants in the prevalence of wrist pain. It can be stated that there is a likelihood of a relationship between social network and online game addiction with wrist pain. Therefore, due to high prevalence of this addiction among students, appropriate planning should be taken to reduce complications and injuries, especially in the wrist area of them.

Firefighting is a stressful job with great degree of physical and psychological demands. The effort-reward imbalance and fatigue need for recovery in this occupational group can lead to the serious consequences. The present study tries to assess the influences of the personal variables on the effort-reward imbalance and fatigue need for recovery.   In this cross sectional study, 107 industrial firefighter were recruited in 2018. The effort-reward imbalance and fatigue need for recovery questionnaire were used to collect the required information. The data analyzed by multiple linear regression with SPSS 16 and statistical significance level was less than 0.05. More than 70 percent of the population study reported a desirable level of effort-reward imbalance and fatigue need for recovery status. The results of regression analysis revealed a meaningful relation among personal variables and contractual status with need for recovery index. In addition, a meaningful relation was found between the type of contractual status, sleep disorders and hypnotic drug with over-commitment. However, there was no meaningful relation for effort-reward imbalance.  The results showed a relative desirable status for effort-reward imbalance and need for recovery in the study group. It is recommended to intervene in working condition to obtaining more precise results.

Nowadays, the importance of workload has become more apparent in ergonomic studies. Because workload is part of unsafe situation, it can be the cause of the incident. Therefore, its quantification is important in different occupations. This study was conducted to evaluate the validity and reliability of the DALI questionnaire for assessing the mental load of drivers. The present study is a cross-sectional and descriptive-analytic study. All bus drivers operating in one of the manufacturing companies (100 people) entered the study. In order to evaluate the validity, academic experts and queue experts (Lay Experts) were used. To assess the reliability of the questionnaire, 10 people were selected and the Cronbach's alpha and intra-cluster correlation test were used to test the reliability. Data was analyzed using SPSS version 18 software. The mean (SD) age of participants was 50.8 (8.29) years and the mean (SD) of work experience among drivers was 22.18 (6.22) years. To assess the reliability of the questionnaire, Cronbach's alpha coefficient was used to determine the effective factors in the questionnaire higher than 0.7. Also, intra-cluster correlation coefficient of the questionnaire was higher than 0.7 in all factors affecting the interference factor, which was moderate, which is in the optimum level. Due to the fact that the validity and reliability indices of the questionnaire were all reported to be desirable, the Dali questionnaire (DALI) as a valid and reliable questionnaire in Iran can be used to examine and measure the mental load of drivers.

Regarding development of several thermal indices and limitations of these indexes, in this research we were examined the applicability and validity of Modified discomfort index (MDI) in Outdoor occupational environments.
This cross-sectional study was done on 175 subjects in summer (2016) in 12 mines construction materials of Tehran Province. Environmental and Physiological parameters (oral temperature, tympanic temperature and skin temperature) were measured simultaneously at three periods; also Modified discomfort index (MDI) together with three other Direct Indices include Wet-bulb globe temperature (WBGT), Oxford index (WD) and Wet-bulb dry temperature (WBDT) were calculated. For survey of applicability and validity of Modified discomfort index, the correlation between this index and other Direct Indices at different times of day with Physiological parameters was determined through the Pearson correlation coefficient.
The results showed that MDI index had more correlation with environmental parameters (dry bulb temperature and relative humidity), also very high correlation coefficient with wet-bulb temperature and black-globe temperature. Among the thermal indices used in this study, MDI index had more correlation coefficient with three other indices. On the other hand; MDI had the highest correlation coefficient with oral temperature and the higher correlation with the tympanic and skin temperature after the WBGT index. In all cases, there was a very good correlation between MDI and other indicators at different times of day.
It can be concluded that MDI, despite being simple, lack of need for sophisticated equipment to measure, having a high correlation with physiological parameters, low cost and easy interpretation can be used as substitute for the WBGT index in the range of temperature and humidity study.

Working in hot environments is one of the common hazards in the workplaces, which can cause heat-related illnesses, affect workers’ health and increase a risk of occupational injuries and accidents. Several indices have been introduced to evaluate the heat stress that each one has own limitations. The aim of this study was to assess and compare thermal indices of humidex, DI and ET with physiological indices in the open-pit mines in Tehran province, Iran.
This cross-sectional study was conducted in summer 2016 on 175 male workers in 12 construction materials mines in Tehran province, Iran. Environmental and physiological parameters were measured simultaneously at three periods and thermal indices were determined as well. In this study, correlation coefficients of indices at different times of day were analyzed. Data were analyzed using SPSS 18 software and Pearson correlation coefficient.
The findings showed that all three indices used in this study had an appropriate relationship with core body temperature. The physiological indices of oral temperature showed a greater correlation coefficient with thermal indices compared to the tympanic membrane temperature and skin temperature. Humidex had a high correlation coefficient with environmental parameters and physiological responses. On the other hand, among the thermal indices used in this study, Humidex had more correlationcoefficient with two other indices.
It can be concluded that humidex, among the studied indices, despite being simple, lack of need for sophisticated equipment to measure, low cost and easy interpretation can be used as substitute index in open-pit mining.

One of the most important elements of successful implementation and management an ergonomics program in an organization is to have suitable goals. In any industry, the goals of ergonomic interventions should be known and understood to determine their benefits. This study aimed to identify and determine the most important goals of ergonomic interventions from the perspective of experts of Iran in the industries using fuzzy Delphi method. In this qualitative study, which is carried out in 2016, the viewpoints of ergonomics experts of Iran were collected during the three-phase fuzzy Delphi through a series of questionnaires. The data was analyzed using content analysis and fuzzy logic. The ergonomics experts have identified eight criteria as the goals of ergonomic interventions which include increasing employee productivity, reducing staff fatigue, promoting physical health, increasing safety, enhancing job satisfaction, improving the quality of products or services, reducing compensation costs and increasing immaterial value and reputation of organizations. The first five criteria with an average of more than 70% agreement have been reached a consensus by the experts. "Increasing productivity", "reducing fatigue" and "improving physical health" are the most important goals of ergonomic interventions considered as ergonomic criteria to evaluate an ergonomics program. The viewpoints of the Iranian ergonomics experts had a lot in common and were really close to the global approach based on International Ergonomics Association definition of ergonomics and human factors.

To investigate associations between computer use data and sleep quality among university students. This descriptive, cross-sectional study was performed on 312 students of Tehran University of Medical Sciences, Iran. Data was collected using Epworth Sleepiness Scale (ESS), Insomnia Severity Index (TSI), Pittsburgh Sleep Quality Index (PSQI), and a background and computer use questionnaire. Descriptive statistics, independent samples test, Univariate analysis of variance and Chi Square test were used to analyze the data. The final sample was composed of 164 (52.6%) male and 148 (47.4%) female students aged 17-30 years. The mean of assessed sleep indices were not significantly different between the male and female groups (P =. 05). Among all the participants, 81.1% were poor sleepers (PSQI ≥ 5), 60.58% of them suffered from insomnia (ISI ≥ 8), and 49.36% of them reported sleepiness (ESS ≥ 10). There was a significant association between the computer work (hours/ day) and ISI and PSQI indices (P =. 05). Students who used computer between 24:00 to 2:00 had a meaningful higher ISI and PSQI indices compared to those whose computer use interval was 19:00 to 22:00. The prevalence of eye discomfort and the headache associated with computer use was significantly more common among female students. We found a significant association between the headache precededby computer use and ISI and PSQI indices (P =. 05). Poor sleep quality and insomnia were common among university students. The amount of prevalence was higher among nocturnal (24:00-2:00) computer users and those with prolonged durations of use. Also, the headache associated with computer use deteriorates the quantity and quality of sleeping.