Effect of heat stress on DNA damage: a systematic literature review.

Thermal stress has a direct effect on various types of DNA damage, which depends on the stage of the cell cycle when the cell is exposed to different climate conditions. A literature review was conducted to systematically investigate and assess the overall effect of heat stress and DNA damage following heat exposure. In this study, electronic databases including PubMed, Scopus, and Web of Science were searched to find relevant literature on DNA damage in different ambient temperatures. Outcomes included (1) measurement of DNA damage in heat exposure, (2) three different quantification methods (comet assay, 8-hydroxy-2-deoxyguanosine (8-OHdG), and γ-H2AX), and (3) protocols used for moderate (31) and high temperatures (42). The evidence shows that long exposure and very high temperature can induce an increase in DNA damage through aggregate in natural proteins, ROS generation, cell death, and reproductive damage in hot-humid and hot-dry climate conditions. A substantial increase in DNA damage occurs following acute heat stress exposure, especially in tropical and subtropical climate conditions. The results of this systematic literature review showed a positive association between thermal stress exposure and inhibition of repair of DNA damage.

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.

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

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

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

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

Combined effect of whole-body vibration and ambient lighting on human discomfort, heart rate, and reaction time.

PURPOSE: This study aimed to investigate the effect of whole-body vibration and ambient lighting, as well as their combined effect on human discomfort, heart rate, and reaction time in laboratory conditions. METHODS: 44 men were recruited with an average age of 25.4 ± 1.9 years. Each participant was subjected to 12 experimental steps, each step lasting five minutes for four different vibration accelerations in X, Y, and Z axes at a fixed frequency; three different lighting intensities of 50, 500, and 1000 lx were also considered. At each step, a visual computerized reaction test was taken from subjects and their heart rate recorded by pulse oximeter. In addition, the discomfort rate of subjects was measured using Borg scale. RESULTS: Increasing vibration acceleration significantly increased the discomfort rate and heart beat but not the reaction time. Lack of lighting caused more discomfort in the subjects, but there was no significant correlation between lighting intensity with heart rate and reaction time. The results also showed that the combined effect of vibration and lighting had no significant effect on any of the discomfort, heart rate, and reaction time variables. CONCLUSIONS: Whole-body vibration is an important factor in the development of human subjective and physiological reactions compared to lighting. Therefore, consideration of the level of vibration to which an individual is exposed in workplaces subject to vibration plays an important role in reducing the level of human discomfort, but its interaction with ambient lighting does not have a significant effect on human subjective and physiological responses.

Evaluation of the effects of occupational noise exposure on serum aldosterone and potassium among industrial workers.

The existing literature indicates that occupational exposure to noise may have adverse effects on workers' health. The aim of this study was to evaluate the possible effects of exposure to different sound pressure levels (SPLs) on serum aldosterone and potassium concentration among Iranian blue collar workers in Golgohar Mining and Industrial Company in Sirjan, Kerman Province, Iran. This case-control study was performed on 45 workers of Golgohar Mining and Industrial Company. The subjects consisted of 30 workers from manufacturing departments and 15 office employees of the mining company. The controls, mainly with administrative jobs were exposed to 72 dBA SPL. Cases, in two separate groups, were exposed to noise levels of 88 dBA and 103 dBA, respectively. Noise intensity was measured at the desired locations. Noise measurements were performed according to the International Organization for Standardization (ISO) 9612. To measure the serum aldosterone and potassium concentrations, a 5 mL blood sample was taken from each worker at the specified time intervals and aldosterone concentration was determined using enzyme-linked immunosorbent assay (ELISA) test in the laboratory. Repeated measurement and Spearman's correlation coefficient analysis were used with α = 0.05. Exposure to the different levels of sound pressure resulted in different aldosterone concentrations and meanwhile an increase in the SPL did not affect the concentration of potassium. From 10:00 AM to 10:30 AM, as SPL increased, aldosterone concentrations did not increase significantly but from 13:30 PM to 14:00 PM, raised SPL led to a significant increase in aldosterone concentration. However, there was no correlation between the concentration of potassium and different factors. This study indicated that increases in SPLs affect aldosterone concentration but at the same time do not have significant effects on serum potassium level.

Memory loss risk assessment for the students nearby high-voltage power lines-a case study.

With increasing sources of alternating current electromagnetic fields (EMFs) in everyday life, their possible harmful effects on human health are a main area of concern in many countries. Given that children are the most valuable assets of each country, it is of utmost importance to study the effect(s) of EMF exposure on various health aspects of members within this age group. The present research is the first systematic study of the effects of exposure to electric substations on the memory status of male students in the age group of 10 to 12 years. The flux density values of extremely low frequency magnetic field were measured at four elementary schools in Tehran in accordance with IEEE std 644-1994. The device was 3-axis (X, Y, and Z) Gauss Meter, model: TES-1394. The students from two schools nearby a high voltage electricity substation (at distances of 30 and 50 m) were selected as the exposed group, and the students of two other schools at further distances of 1390 and 610 m were considered as the control group. To determine the status of working memory in the students, the questionnaire was adapted from Wechsler Intelligence Scale for Children (WISC-IV). The completed questionnaires were analyzed by t test and chi-square using SPSS 20. The average magnetic flux density was 0.245 µT at case schools and 0.164 µT at control schools, P < 0.01. The demographic characteristics of the students in the two groups were not statistically different. However, the difference in working memory was significant at the level of 5 %. The results of the questionnaire data showed that students in the control group had better working memory compared to students in case group. The findings revealed a reverse correlation between magnetic flux density and working memory of students (R = -0.255). It is concluded that extremely low frequency magnetic field exposure may have a negative impact on the working memory of children, but further studies are necessary to reach a definitive conclusion.

Hazard zoning around electric substations of petrochemical industries by stimulation of extremely low-frequency magnetic fields.

Electromagnetic fields in recent years have been discussed as one of the occupational hazards at workplaces. Hence, control and assessment of these physical factors is very important to protect and promote the health of employees. The present study was conducted to determine hazard zones based on assessment of extremely low-frequency magnetic fields at electric substations of a petrochemical complex in southern Iran, using the single-axis HI-3604 device. In measurement of electromagnetic fields by the single-axis HI-3604 device, the sensor screen should be oriented in a way to be perpendicular to the field lines. Therefore, in places where power lines are located in different directions, it is required to keep the device towards three axes of x, y, and z. For further precision, the measurements should be repeated along each of the three axes. In this research, magnetic field was measured, for the first time, in three axes of x, y, and z whose resultant value was considered as the value of magnetic field. Measurements were done based on IEEE std 644-1994. Further, the spatial changes of the magnetic field surrounding electric substations were stimulated using MATLAB software. The obtained results indicated that the maximum magnetic flux density was 49.90 µT recorded from boiler substation, while the minimum magnetic flux density of 0.02 µT was measured at the control room of the complex. As the stimulation results suggest, the spaces around incoming panels, transformers, and cables were recognized as hazardous zones of indoor electric substations. Considering the health effects of chronic exposure to magnetic fields, it would be possible to minimize exposure to these contaminants at workplaces by identification of risky zones and observation of protective considerations.

Establishing research impact assessment in Iran: The first report from a non-high-income country.

Background: This study presents the first report on research impact assessment (RIA) in non-high-income countries, undertaken as a pilot initiative in 2021. Within it, we aimed to explore the feasibility of employing the 'payback' model for evaluating the impact of health research and enhancing the accountability of universities. We focussed on three key impact domains: 'production of decision support documents and knowledge-based products,' 'implementation of research results,' and 'health and economic impact.' Methods: We adopted a case study approach to assess the impact of 5334 health research projects conducted by researchers from 18 universities from 2018 to 2020. Researchers were required to submit evidence related to at least one of the specified impact domains; six scientific committees verified and scored claimed impacts at the national level. Results: Only 25% of the assessed projects achieved impact in at least one domain, with the production of decision support documents and knowledge products being the most reported impact. Notably, economic impact was verified in only three projects, indicating room for improvement in this area. Technology research exhibited the highest acceptance rate of claimed impact, suggesting a positive correlation between technology-focused projects and impactful outcomes. Conclusions: This study demonstrates the feasibility of employing a case study approach and the 'payback' model to evaluate the impact of health research, even within the constraints of a moderately equipped research infrastructure. These findings underscore the potential of integrating RIA into the governance of health research in Iran and other non-high-income countries, as well as the importance of using RIA to assess the accountability of health research systems, guide the allocation of research funding, and advocate for the advancement of health research. The study sets a precedent for future assessments in similar contexts and contributes to the ongoing global dialogue on the societal impact of health research.

White Noise and Its Potential Applications in Occupational Health: A Review.

Background: White noise (WN), because of its unique behavior and characteristics, has different applications in different sciences. Nevertheless, the results of studies and reviews of the literature on occupational safety and health found that this type of noise is often used as a noise source to assess the effects of hearing and its physical characteristics. Its possible applications in this area have not received as much attention. The present review study aimed to answer the question, "Can WN be used as a means of promoting occupational safety and health at the workplace?". Methods: In this review, we reviewed the articles published in reputable databases from 1990 to 2020. Our study included 33 articles from 120 that were searched in full text and followed the inclusion and exclusion criteria. Results: Various applications were examined, including noise masking, white noise therapy, cognitive functions, and sleep. WN can enhance the work environment and meet occupational safety and health objectives based on the study's results. The results of this study will provide a basis for continuing research into the use of WN in the workplace as an engineering and management control method. Conclusion: WN is being used in various fields that may hold promise for its application in occupational health sciences and maintaining the well-being of workplace workers.

Investigating the effect of workwear textile modification with nanometal-embedded PMMA polymer by a spray method on textile air permeability, bending stiffness and surface temperature induced by near-infrared.

Objectives. This study aimed to optimize modification of cotton-polyester textiles of workwear in terms of air permeability (AP), bending stiffness (BS) and near-infrared (NIR) reflectance using nanometal-embedded polymethyl methacrylate (PMMA) polymer by a spray method. Methods. This experimental study was carried out to modify cotton-polyester textiles using nanoparticles of aluminum oxide (Al2O3), tin oxide (SnO) and zinc oxide (ZnO) embedded in PMMA polymer with different weight percentages by a spray method under 215-psi pressure. The surface temperature of the textiles induced by the NIR spectrum and their comfort in terms of AP and BS were measured according to Standard No. ASTM D737 and BS 3356, respectively. Results. Cotton (65%)-polyester (35%) textiles can be modified with a PMMA-based aluminum and zinc nanoparticle composite with equal weight percentage using a pressurized spray method with good durability. Also, most NIR reflection is in the textile coated with aluminum and ZnO nanoparticle composite in the PMMA base. Conclusions. It is recommended that this composite be used in future studies to impregnate the clothing textile of outdoor workers in hot and arid regions by a spray method under pressure and its effects be investigated on reducing heat stress in these workers.

An investigation on the noise reduction performance of profiled rigid median barriers at highways.

Median barriers as a portion of a divided highway are provided to minimize the cross-median crashes. Moreover, median barriers similar to roadside noise barriers could protect people from transportation noise. Thus, there is a need to investigate various median barrier models to identify changes of insertion loss over a simple rigid barrier. In order to estimate the acoustical influence of median barrier's profile in the shadow zone, different median barrier models are presented and their insertion losses are calculated over a frequency range from 50 to 4000 Hz using a two-dimensional boundary element method. The present investigation has clearly revealed that among the profiled median barriers, T-shape, Y-shape, and L-shape provide better performance than that of the other shapes. It is also found that among inclined barriers, V-shape barrier significantly presents higher values of attenuation. Based on the calculation of different geometrics, it has been shown that a further 2 dB (A) in efficiency could be obtained by a better design of the median barrier which is labeled model "L."

Noise pollution survey of a two-storey intersection station in Tehran metropolitan subway system.

According to the world population increase and demand on transportation in mega cities, modern and low-cost technologies are remarkably considered. Meanwhile, subway system, as a means to transfer a large population of people, is extremely welcomed due to its particular advantages including time and cost savings, traffic jam avoidance, and unaffected by weather. Nevertheless, despite the benefits of these technologies, such devices also have been associated with disadvantages for human. In many subway systems, noisy environments are clearly observed; therefore, workers and even the passengers are exposed to higher noise levels than permissible limit. In this research, noise measurements were performed at Imam Khomeini Station as the most crowded intersection subway station in Tehran. In this descriptive-sectional survey, the amount of noise pollution was investigated at both stories of Imam Khomeini Intersection Station. A variety of noise pollution indicators such as L(eq) 10 min were separately measured at each storey through five measurement points from 7 A.M. to 10 P.M. It was shown that the equivalent sound level range at Imam Khomeini station towards Elmo Sanat and Imam Khomeini towards Mirdamad were between 70.56-79.54 and 68.35-79.12 dB (A), respectively. It was indicated that except for the entrance stairs to the subway waiting platform and the first section of the platform on both stories, other measurement stations have the same equivalent sound levels.

Evaluation of the relationship between psychological distress and sleep problems with annoyance caused by exposure to environmental noise in the adult population of Tehran Metropolitan City, Iran.

Purpose: The aim of this study was to investigate the association between the psychological distress and sleep problems with environmental noise annoyance in adult population. Methods: This is a cross-sectional study on 822 adult population of Tehran City in 2016. Integrated cluster stratified random sampling and Kish grid method were used. Noise annoyance, the day-night average sound level (Ldn), nighttime average sound level (Lnight), and daytime average sound level (Lday) were selected as noise exposure indicators. The prevalence of psychological distress and sleep problems were assessed using the Kessler Psychological Distress Scale (K10) and the PSQI questionnaire, respectively. Multiple logistic regression analysis was applied for data analysis. Results: Among the participants 46.03%% were exposed to a sound level higher than the daytime standard level (55 dB) and 84.6% were exposed to a level higher than the nighttime standard limit (45 dBA). According to the results, 49% of the subjects had poor sleep quality and 66% were highly sensitive to noise. In addition, 17.73% had a high risk of mental disorders and 16.48% were found to have a mild risk of mental disorders. There was found a statistically significant association between psychological distress and the noise annoyance at home (OR = 1.3 CI 95% (1.17-1.44)) and at work environment (OR = 1.18 CI 95% (1.08-1.28)). Conclusion: The findings indicated that the study population was highly sensitive to noise. In addition, the relatively high percentage of people who exposed to non-standard levels of sound indicates that this exposure has the potential to cause physical and mental consequences among them.

Burden of diseases attributed to traffic noise in the metropolis of Tehran in 2017.

Although road traffic noise is the most important source of environmental noise emission in large cities, little is known about health burden. The present study was conducted to estimate the burden of diseases attributed to traffic noise in the metropolis of Tehran in 2017. Using noise maps provided by the municipality of Tehran, we calculated population exposure distribution in term of Ldn and Lnight and the number of DALYs lost due to ischemic heart disease, hypertension, high sleep disturbance, annoyance and stroke endpoints based on the World Health Organization Environmental Noise Guidelines for the European Region. We applied published dose-response functions to estimate the traffic noise burden for high sleep disturbance and annoyance. We estimated 61,284 DALYs or 697 DALYs per 100,000 population attributed to traffic noise in Tehran for the reference year 2017. Highly sleep disturbance with a share of 58.74% of the DALYs was recognized as the most important contributor of disease burden, and noise annoyance with a share of 23.12% was ranked next. Ischemic heart disease (11.71%), stroke (5.12%), and hypertension (1.31%) were ranked third to fourth, respectively, in terms of the burden of disease caused by environmental noise. A considerable fraction of the population of Tehran lives in areas with an environmental noise higher than the standard level. The findings showed that traffic noise pollution is an important environmental risk factor in Tehran imposes the greatest burden on the community, mainly through highly sleep disturbance and noise annoyance endpoints.

Development and validation of an individual job performance questionnaire (IJPQ).

BACKGROUND: Developing reliable tools to tap into all the behavioral dimensions of individual job performance and identifying the right sub-dimensions is necessary for both research and practice. OBJECTIVE: This study aimed at developing and validating an IJPQ that addresses shortcomings of existing questionnaires. METHODS: After a comprehensive systematic literature review, a framework consisting of four dimensions, including task performance (TP), contextual performance (CP), counterproductive work behavior (CWB), and adaptive performance (AP) was structured for measuring IJP. As well, 45 sub-dimensions were identified for measuring IJP's dimensions. Content and face validity were evaluated, and item impact score (IS), content validity index (CVI), Kappa, and content validity ratio (CVR) were calculated. For reliability and confirmatory factor analysis (CFA), 525 workers completed the validated questionnaire and Cronbach alpha and goodness of fit indexes were determined, respectively. RESULTS: Of the 62 items generated to measure dimensions, 53 were approved. Based on item-level CVI, of the 53 items, only 45 items were accepted. Finally, the results of item level CVR led to the extraction of 27 questions to evaluate IJP. The obtained scale level CVI and scale level CVR were 0.91 and 0.68, respectively. Based on the results obtained from 525 Iranian workers, values of Cronbach's Alpha, X2/df, RMSEA, and P-value were in the acceptable range. CONCLUSIONS: Conclusively, a questionnaire containing 20 items was developed and validated for measuring IJP of Iranian worker's culture. The four dimensions of TP, CO, CWB, and AP consisted of 6, 5, 5, and 4 items each, respectively. Overall, IJPQ is a theory-based, reliable, and valid instrument for assessing job performance.

Thermal stress and TiO2 nanoparticle-induced oxidative DNA damage and apoptosis in mouse hippocampus.

Titanium dioxide (nano-TiO2) is used abundantly in various industrial products and novel medical therapies. In addition, the impact of climate change on the health and safety will undoubtedly increase in the future. However, the effects of exposure to these nanoparticles and heat stress on hippocampal DNA damage and apoptosis remain unclear. This study was conducted to evaluate the DNA damage and apoptosis in the hippocampal tissue and the physiological responses in mice induced by intraperitoneal (i.p.) administration of TiO2 nanoparticles (NPs) and heat stress for 14 consecutive days. The results showed that heat stress and TiO2-NPs were induced in the mouse hippocampus that led to hippocampal reactive oxygen species generation, oxidative damage of DNA, and apoptosis in a partly dose-dependent manner, especially at very hot temperature. High doses of nanosized TiO2 and severe heat stress significantly damaged the function of the hippocampus, as shown in the comet assay and apoptosis tests. The results of this study may provide data for appropriate measures to control and assess the risk of nano-TiO2 and thermal stress hazards to human health, especially workers. Safety guidelines and policies should be considered when handling nanomaterials in a hot environment.

Investigating the role of internal layout of magnetic field-generating equipment on workers' exposure at power substations.

Introduction. This research is an attempt to show the role of interior layout of equipment in generating magnetic fields. Materials and methods. The levels of an extremely low-frequency magnetic field were measured in accordance with Standard No. IEEE 644:1994 in three substations and a control building in a petrochemical power plant in southern Iran. Then, workers' occupational exposure (time-weighted average [TWA]) was calculated and the sources of maximum magnetic field generation at each place were identified. Their interior design was changed to achieve the optimal layout of equipment subsequently; the workers' TWA was recalculated for the new situation. Results. The obtained results showed that electrical engineers and technicians were exposed to the maximum TWA of 10.14 µT. The operators in the control room were exposed to the lowest TWA of 0.84 µT. The results also showed that after the change of interior design and proper layout design of the equipment in the substations, the TWA was reduced by 0.73 µT. Conclusion. The research findings revealed that the most harmonious arrangement of equipment in an industrial unit plays a major role in reducing the exposure of workers to magnetic fields and ultimately increases the level of their health in the workplace.

The combined effect of industrial noise type, level and frequency characteristics on hand motor skills: A lab trial study.

BACKGROUND: The study aimed to assess the interactive effects of industrial noise type, level and frequency characteristics on hand motor skills using the Minnesota Manual Dexterity Test and the Hand Tool Dexterity Test. METHODS: A total of ten nonsmoking male volunteers with normal hearing and vision were selected for this study. The study followed a full 3×3×2 factorial design. Independent variables were noise type (steady, intermittent and fluctuating), noise level (75, 85 and 95 dBA) and frequency characteristics ("roar" <2000 Hz and "hiss" >2000 Hz). RESULTS: For Minnesota Manual Dexterity Test, the lowest speed is related to steady hiss noise at 75 dBA and the highest speed is related to fluctuating roar noise at 95 dBA. The speed is being significantly affected by the frequency characteristic (P = 0.041) and noise type (P = 0.025). The effect of hiss noise on speed is greater than roar noise (P = 0.038). There is a significant difference (P = 0.035) between continuous noise and fluctuating noise. For the Hand Tool Dexterity Test, the lowest speed is related to fluctuating hiss noise at 95 dBA and the highest speed is related to steady roar noise at 95 dBA. The speed is being significantly affected by the frequency characteristic (P = 0.002), noise type (P = 0.0001) and noise level (P = 0.005). The effect of hiss noise on response variable to be greater than roar noise (P = 0.008). There is a significant difference (P = 0.0001) between steady noise and the two other types of noise, and also there is a significant difference between 75 dBA and 85 dBA level (P = 0.003). CONCLUSIONS: The results showed that on hand motor skills, speed response was influenced by three characteristics: the type of noise, frequency characteristics and noise level. Also, the effect of the hiss noise was more than the roar noise.

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

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