fatemeh fasih-ramandi

In recent years, exposure to nanomaterials has been known as a challenge among occupational health experts. In this line, personal protective equipment has been considered as a solution to reduce the worker’s exposure. Since respiratory and skin tracts represent the most common workplace exposure routes, knowledge of the efficiency of respiratory and skin protection equipment is particularly important. So, the aim of this study is the assessment of the efficiency of respiratory and skin protection equipment toward controlling nanoparticles in the workplace with a scoping review approach.

This study was conducted in 2022 with a scoping review approach. Arksey and O’Malley’s five-step framework was chosen as the research method. The search strategy was followed in the databases necessary to access the research data, including PubMed, Google Scholar, Science Direct, Web of Science, and Scopus. Also, EndNote X9® and Microsoft Excel software were used to collect and analyze studies, respectively.

In the first step, 1014 articles were identified. Finally, 38 articles were included in the study to examine quantitative and qualitative information about the efficiency of respiratory and skin protective equipment. Twenty-five articles were related to breathing masks, and six studies were about protective gloves, and seven other articles were devoted to protective clothing. According to the studies of breathing masks, the mean total penetration of nanoparticles was estimated at 2.27%. Also, based on the studies of protective clothing, the maximum penetration of nanoparticles was 30nm for protective clothing made of polypropylene and polyethylene with different layers.

Although the efficiency of existing personal protective equipment showed a good result for controlling nanoparticles, the size of nanoparticles is one of the essential parameters in determining the efficiency of the equipment, which should be considered the workplaces. So, it is recommended that more studies be considered to improve their efficiency, and standard tests should be developed to evaluate them.

Recent years have seen many attempts to increase the efficiency and reduce the pressure drop of High-Efficiency Particulate Air Filter (HEPA) filters in removing microorganisms through shape change and the use of photocatalysts. This study is the first scoping review of the effects of photocatalysts on increasing the efficiency of HEPA filters in the elimination of airborne microorganisms.

PubMed, Scopus, Irandoc, and Magiran databases were searched for relevant articles. Based on select keywords and the study objectives and applying the inclusion and exclusion criteria, eight from a total of 315 articles were identified, two of which were typical in the review of efficiency and pressure drop. These articles investigated the effect of photocatalyst and filter shape on the efficiency and pressure drop of HEPA filters.

These studies were released from 2000 to 2021. TiO2, with its long-term interactions with microorganisms, the attack of superoxide radicals (O2•−), and the release of K+, RNA, proteins, and other essential components will cause their destruction. Ultraviolet rays at a wavelength of 254 nm remove bacteria on the surface of the filter. The synergy of the inherent ability of UV radiation with TiO2 through nucleic acid and protein damage in microorganisms and the generation of oxidative radicals increases the efficiency of HEPA filters compared to either one alone.

The photocatalysts with ultra-violet rays on the HEPA filter can reduce the problem of microorganism growth and increase indoor air quality.

To ensure employee safety and health, it is crucial to choose and use personal protective equipment correctly. An investigation of the respiratory and hearing protection equipment used in the industries of Tehran was conducted in the present study.

This study was a descriptive-analytical study conducted in 2023 on 400 occupational health and safety experts in Tehran province. A researcher-made checklist and questionnaire (physical and online versions) were used to determine the criteria that are considered when selecting protective equipment. Statistical analysis and graphing were performed using SPSS-v21 and Excel-2016.

Participants had an average age of 38.66 and an average work experience of 11.78 years. The participants reported 48.3% and 47.7% disapproval of the quality and 42.5% and 39.5% disapproval respectively of the quantity of respiratory and hearing protection equipment available in their industrial units. In addition, 56.3% of them admitted that they have no responsibility for providing or approving the equipment in their workplace. Overall, 27 and 29 criteria were mentioned by study participants pertaining to respiratory and hearing protection equipment, respectively. In the identified criteria, the frequency distribution ranged from 0.3% to 38%.

A high rate of expert dissatisfaction with protective equipment and a low frequency of most of the criteria mentioned indicates that industries aren’t paying much attention to the issue of choosing the right respiratory and hearing protection equipment. To improve the situation, more investigation is needed and practical and operational solutions will be provided. This study highlights the importance of proper selection and use of personal protective equipment in ensuring the safety and health of employees.

Firefighting is one of the most dangerous jobs. Occupational stress is known as an effective factor in increasing the risk of mental and physical problems in the workplace. Therefore, the purpose of this study was to investigate the relationship between job stress and unsafe behavior of firefighting employees.

The present study was a descriptive-analytical type conducted in 2020 among the staff of one of the firefighters in Tehran. 62 people were selected as statistical samples using simple random sampling. In order to assess the prevalence of unsafe behavior and occupational stress, a researcher-made checklist and Health and Safety Executive (HSE) occupational stress questionnaire were used, respectively, and data analysis was performed using SPSS21 software and independent t-test and Pearson correlation tests.

The most unsafe behavior was related to not using the respiratory system in small fires. The lowest and highest levels of job stress related to the relationship between communication and demand were 8.83 and 22.58, respectively, and the total level of job stress was 107.29. No significant relationship was observed between unsafe behavior and job stress dimensions.

The average score of occupational stress was high in all the examined people. Failure to use pants and fire wear and failure to use the experiences of colleagues during fire and accident were a part of the unsafe behaviors of the fire department employees, so the management unit should adopt the necessary training and measures to correct these unsafe behaviors for the fire department employees.

The present study seeks to help the experts and specialists by investigating documents relevant to the harmful chemical compounds and toxic substances used in the production processes of a few novel industries so that, the information gap is identified by recognizing such toxicants and taking steps to fill such gap.

By making the use of keywords related to the objective of the study (keywords such as toxicity, modern toxicity, modern industries (MIs), new toxins, modern/new chemical compounds), the indexed articles were searched from 2000 to 2022 in ProQuest, Science Direct, Pub Med, Scopus, Web of Science, and Google Scholar databases aiming at access to the toxic compounds in several MIs. In this study, out of 116 articles searched as full text and following the inclusion and exclusion criteria, 46 articles were wholly selected.

According to the results, the issues include the nanotechnology industry (silver-nanoparticles, gold-nanoparticles, titanium dioxide, zinc-oxide, cerium-dioxide, and iron-oxide nanoparticles), nuclear technology (cobalt [60 Co and 58 Co], uranium [235U], and plutonium [Pu4+]), semiconductor industries (arsenic compounds, phosphorus, dopants, acids, photoactive compounds, etc.), liquid crystal display industries (indium compounds and indium tin oxide), pharmaceutical and medical (cytotoxic and platinum-based drugs), modern dentistry (resins, silica-nanofillers, barium-glass, and beryllium compounds), as well as the MIs involved in silica, nickel, and dioxin nanoparticles, were documented and discussed.

Developing MIs and equipping the traditional industries with new technologies have confronted humankind with different chemicals and toxins resulting from producing and using products that require attention, study, and research. It is hoped that the present review study will pave the way for extensive studies on occupational health and toxicology in MIs.

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?".

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.

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.

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.

The risk of musculoskeletal disorders due to various work factors such as ergonomic factors in truck drivers is considerable. The aim of this study was to investigate the effect of ergonomic risk factors on the prevalence of musculoskeletal disorders in truck drivers.

This cross-sectional was a descriptive-analytical study that was performed on 200 professional truck drivers by two-stage cluster sampling. The ergonomics and safety of drivers’ questionnaire including demographic characteristics, working conditions (stress and job satisfaction), pain in nine areas of the body in the last 12 months based on body map were used. The central indicators and Spearman non-parametric statistical tests were used to analyze the data.

The mean (±standard deviation) age of drivers was 47.5±9years, who drove an average of 10.66 hours in 24 hours. 99.5% of drivers complained of low back pain, of which 40% were mild and 59.5% were severe. Also, 59.5% reported severe pain in the knee area. The relationship between pain in the elbow and foot with moving and carrying of loads as well as neck and wrist pain with hand and arm movements was significant (p<0005). No significant relationship was found between pain in nine areas of the body and job satisfaction.

Ergonomic risk factors play an important role in the occurrence of musculoskeletal pain in drivers, which requires special training and attention to this occupational group along with preventive and therapeutic measures.

Taking the drivers' health into account from different perspectives is important. This study aimed to examine how heavy vehicle drivers' blood parameters are related to their road accident risk.

A descriptive study was conducted among 200 drivers of heavy vehicles. The blood parameters were determined based on the medical records of drivers, as well as data on accidents, demographics, and occupational factors reported in a standardized questionnaire assessing the safety of drivers. The examined drivers' blood parameters included markers for white and red blood cells, platelets, hemoglobin, fasting blood sugar, cholesterol, and triglyceride. Nonparametric statistical tests and logistic regression were used to analyze the data by SPSS-v.21.

Mean and standard deviation of age, BMI, and daily working hours of drivers were 47.5±9, 27.9±2.99, and 10.66±2.52, respectively. Most drivers were normal in terms of white and red blood cells, hemoglobin, and platelet, while 22.5%, 29%, and 26% were suffering from abnormal conditions in terms of fasting blood sugar, total cholesterol, and triglyceride, respectively. A study of the impact of blood parameters on accidents revealed that red blood cells, fasting blood sugar, and triglyceride levels were significantly different in three groups of drivers with different numbers of accidents and near-misses. Based on the logistic regression analysis, the number of cigarettes per day, age, exercise hours, and blood hemoglobin contributed to accidents.

This study supports the concept that blood parameters, such as hemoglobin, fasting blood sugar, total cholesterol, and triglyceride, can influence the safe performance of drivers and road accidents.

The study of noise has always been of interest to occupational health professionals as a harmful physical factor in the workplace. However, the psychological and psychoacoustic aspects of noise in the workplace have been less studied. This study has dealt with different colors of noise and their applications in psychoacoustics.

This review study was conducted by searching the databases of Google Scholar, ProQuest, Science Direct, PubMed, and Scopus to extract the articles related to the research subject within a 50-year interval from 1970 to 2020.

Based on the results of the present study, colored noises and white noise seem to have the potential to be used as acoustic stimuli to improve the sleep of employees, especially shift workers, to improve memory and attention, especially in jobs that require high care and attention. Colored noise and white noise have potential applications to improve cognitive function in different occupations to reduce the activity of the sympathetic nervous system and anxiety and stress, especially in jobs with high job stress. Also, these noises are helpful for people’s privacy, especially in the open workplace, for noise masking and noise control purposes, as well as for medicine and treatment of disorders such as tinnitus, ADHD, and hyperacusis.

Paying attention to the colors of noise and their psychoacoustic impacts shows us that the noise impacts are not limited to their undesirable and damaging effects. Instead, their positive and applied aspects should also note. Familiarity with such aspects and their introduction can identify the existing information gaps in this field and pave the way to fill them.

The association between the occurrence of road accidents and WMSD is a topic that has attracted much attention in the transportation industry. This study aimed to investigate the prevalence of musculoskeletal disorders in professional truck drivers and their impact on the occurrence of road accidents.

In this descriptive study, 200 professional truck drivers were selected by a two-stage cluster sampling method from occupational medicine centers in Tehran province, Iran in 2017. The data were collected from the two groups of with and without accident. The three-part questionnaire on ergonomics and safety of drivers was used, which included items asking about demographic characteristics, stress, job satisfaction, details of accidents, and the severity of musculoskeletal disorders in nine areas of the body. The central indices and non-parametric statistical tests (Kruskal-Wallis, Spearman) were applied to analyze the data using spss Ver 24.

The highest frequency of pain was observed in drivers without and with accidents in the back, knees, and shoulders, respectively; however, the most severe pain was reported for the low back and neck. Drivers between 45 and 60 years old reported the highest number of accidents. The association correlation between the number of road accidents and stress score among drivers with accident experience was negatively significant (P > 0.05). However, the association between musculoskeletal disorders and accidents was not statistically significant.

Factors other than musculoskeletal disorders were involved in road accidents that require more investigations.

A driver's health status may have a crucial impact on the prevention of road accidents. This study was conducted to investigate drivers' health status and its effects on road accidents among drivers of heavy vehicles in Iran. A cross-sectional study was conducted to examine the health status of 200 heavy vehicle drivers selected via a two-stage cluster sampling approach from occupational medical centers in Tehran Province, Iran. The related data were collected using the standard drivers' safety and ergonomics questionnaire, body map work-related musculoskeletal disorders (WMSDs) questionnaire, and drivers' medical records at occupational medical centers. Data were statistically analyzed by SPSS v.21 and Microsoft Excel 2016. Body mass index results classified 69% of drivers as overweight, and 19.5% as obese. 88% of drivers were stressed out and 35% were dissatisfied with their jobs. On average, 63% of drivers showed unsafe behavior while driving, and 80% had levels of WMSDs in 9 body regions. For the drivers with and without accidents, the mean and standard deviation values of hearing loss were 18.20±14.84 dB and 35.45±18.65 dB, respectively. In 79.3% and 75.9% of drivers who had accidents, respectively, their right and left visual acuities were smaller than 10:10. In 55% of the drivers, the status of the main pulmonary function variables was abnormal. The study group had high levels of fasting blood sugar (FBS), total cholesterol, and triglyceride, by 22.5%, 29%, and 26%. There was a significant positive relationship between the number of accidents and loss of hearing and drivers' age. There was also a significant negative connection between the number of accidents and visual acuity, respiratory health, exercise hours, safety, and health training. The results of the present study showed that occupational stress, unsafe behaviors, ergonomic factors, loss of hearing, visual acuity, high blood FBS values, weak respiratory system, and lack of safety and occupational health training were among significant contributors to road accidents. Hence, given the importance of heavy vehicle driving, it is suggested to check out drivers' occupational health and safety more often that ever.

Road accidents, as the main causes of mortality and disability in the world, have been seriously endangering human health. Human factors are among the most significant causes of road accidents. This study aimed to investigate the association between high-risk behaviors among truck drivers with their fatigue and drowsiness in the occurrence of road accidents and near miss accidents.

This descriptive study was conducted recruiting 200 truck drivers in Tehran using two-stage cluster sampling method, in 2019. A standard driver safety questionnaire was used to collect data, with its reliability measured by the test-retest method. The Fisher's test, a chi-squared test, and the Pearson’s correlation were used to analyze the data.

The mean age of the drivers and the mean hour of driving were 47.5 ± 9.05 years and 10.66 ± 2.52 hours, respectively. In addition, the number of accidents had a significant association with the drivers' age, drowsiness, talking on the cell phone, texting, eating snacks, and driving hours. However, it had no significant relationship with drinking tea and smoking. Furthermore, the rate of road accidents had a significant correlation with the drivers' driving time and rest hours.

Behaviors and factors, such as talking on the cell phone, texting, eating snacks, long hours of driving per day, long hours of nonstop driving, low rest hours, and drowsiness were among the major causes of accidents among trucks drivers. In this regard, authorities are recommended to run educational courses to modify high-risk driving behaviors so as to reduce road accidents.

Job stress is one of the most common health-related problems all over the world, which is associated with many physical hazards. The aim of this study was to assess job stress in firefighters and to investigate its association with musculoskeletal disorders.

This work is a descriptive-analytical study and was conducted in one of the firefighting stations located in Tehran. HSE Job Stress Questionnaire and the Kernel Musculoskeletal Disorders Questionnaire were used to assess job stress and musculoskeletal disorders, respectively. Data analysis was performed using SPSS21 software. Ethical considerations were observed in all stages of the study.

Mean age of employees and their working time were 32.66 ± 5.83 years and 9.14 ± 2.1 hours per day, respectively. The lowest and highest levels of job stress were 8.83 and 22.58 and the amount of total job stress was equal to 107.29. Musculoskeletal disorders were very common among firefighters and were in the knee, shoulder, back and neck areas, respectively. Overall score of job stress and role dimensions, support of officials, support of colleagues, demand and change were significantly associated with musculoskeletal disorders.

Job stress and musculoskeletal disorders were very common among firefighters and a statistically significant relationship was observed between job stress and musculoskeletal disorders. Therefore, job stress may be a factor in the development of musculoskeletal disorders in firefighters, so a care system for firefighters is needed to reduce job stress and prevent musculoskeletal disorders.

The Wet Bulb Globe Temperature (WBGT) is still widely applied as a preliminary tool for evaluating heat stress. This index faces some limitations not considered yet. This systematic review was conducted aiming at highlighting some limitations for the development of the WBGT index.

The present study was organized using more extensive databases: PubMed, Google Scholar, Scientific Information Databases (SID), Elsevier, Web of Science, Scopus, Irandoc, Magiran, and Iran Medex. The used search terms were WBGT index, Heat stress, Thermal Stress, Heat strain, Wet Bulb Globe Temperature, Hot Condition, Occupational Health, and Occupational Exposure indices. In this study, 69 articles from 1950 to December 2021 were assessed.

The WBGT index, despite having some advantages, suffers limitations that should be considered for a more accurate estimate of thermal stress. This study pointed to the new limitations; including, the value of WBGT is not clear for persons whose working in a seated posture. The additional problem with the use of this index is that it is used for adapted people who have consumed enough water and salt, while in most hot working environments neither water nor salt is always readily available. Therefore, using this index will cause an error. Also, in heterogeneous environments, if the heat source is near the head or legs, a coefficient will not be applied to these regions. The results of the study demonstrate that, because of the limitations of the WBGT index, it is recommended that this index be used along with other indicators and physiological parameters to assess heat stress until more extensive studies are conducted in an attempt to improve and remove its limitations.

The psychometrics of instruments used for safety performance evaluation is essential for the accreditation of an organization’s safety evaluation and has been emphasized in many studies. Psychometrics pertains to the validity and reliability of an evaluation instrument and describes its precision and consistency. The aim of the present study is the psychometrics of safety level and safety culture questionnaires to provide a reliable and valid instrument for safety performance evaluation in industries.

This descriptive-cross sectional study, was conducted with the intention of psychometric instruments used to evaluate the level of safety and the climate of safety in the Mapna Pars power plant generator manufacturing and engineering company. The face validity of the questionnaires was analyzed quantitatively and qualitatively. In the quantitative method, the importance of the influence score was applied and content validity was calculated using the Lawshe method. Content Validity Ratio (CVR) and Content Validity Index (CVI) were also used. For this purpose, elicitation was obtained from experts within the professional health and safety community. The reliability of the instruments was determined via the Cronbach's alpha test and the Interclass Correlation Coefficient (ICC) test. Finally, the standardized questionnaires were used to evaluate the safety level and safety climate of the industry chosen as the case study. The data obtained were analyzed using the SPSS software solution v20.

Based on the quantitative face validity results obtained at the Mapna Pars company, one question was removed from each of the final instruments. The content reliability analysis revealed that the safety level questionnaire had a CRI of 0.99 and a CVR of 0.91 and is thus acceptable. The safety climate questionnaire had an acceptable CVI of 0.95 and an acceptable CVR of 0.82. Regarding reliability analysis, a Cronbach's alpha of 0.72 and 0.89 was obtained for the safety level questionnaire and the safety climate questionnaire respectively. This indicates an acceptable level of internal consistency for both questionnaires. The re-application of the questionnaires after two weeks revealed a relatively consistent safety level (ICC=0.90) and safety climate (ICC=0.74).

Analyzing the data obtained in the present study shows that the safety level questionnaire with 66 questions and the safety climate questionnaire with 93 questions have suitable validity and reliability and can be used for safety evaluations in similar industries.

The acoustic performance of natural fiber adsorbents has been investigated in numerous studies. A part of these materials show a poor adsorption within the frequency range of less than 1000 Hz. In the present study, attempts were made to investigate the effect of layout sequence of double-layered composites consisting of natural and synthetic fibers on improving the acoustic adsorption coefficient of natural fiber in the low-frequency range (63 to 1000 Hz) using the numerical finite element method.

In this study, the finite element method and the Johnson-Champoux-Allard model in COMSOL software version 5.3a were used to investigate the acoustic performance of the double-layered composites consisting of natural and synthetic adsorbents. The acoustic absorbers under study included date palm fiber, polyurethane foam and cellular rubber. Each double-layered composite included a date palm fiber with 10mm in thickness and a synthetic adsorbent (polyurethane foam or cellular rubber) with 10mm in thickness. In sum, four double-layered composite structures with different layouts of adsorbents in each structure were studied.

The location of natural fiber can play a critical role in the acoustic performance of the double-layered composite structures such that comparing the studied double-layered composites revealed that when the natural fiber was the first layer exposed to the normal sound in the double-layered composites with 20mm in thickness, the trend of acoustic performance was approximately the same as the single-layered composite of natural fiber with 20mm in thickness; but in the composite structures, when the synthetic adsorbent was the first layer exposed to the sound, the trend of acoustic absorption was improved.

On the basis of the results, the double-layered composite structure with a higher-density and lower-porosity upper layer showed a better acoustic absorption trend than the single-layered composite including the natural adsorbent.

The application of particles’ electrical mobility in the electric field has always been an important concern, as the functional basis of a number of particle measuring and classification instrumentations. The objective of this study was to design and construct an aerosol particles classification system using electrical mobility feature in laboratory scale.

This laboratory experimental study was carried out in collaboration with the Atomic Energy Organization of Iran and Shahid Beheshti University of Medical Sciences. The theoretical principles governing the development of the DMAs, the FORTRAN programming software and the Excel-2016 program were used in design and construction of the DMA system. The technical drawings of the constituent parts of the DMA and laboratory layout were carried out using SOLIDWORKS-2017 software. The laboratory instrumentation including the particle generator, particle counter, dry and clean air supply system and high voltage power supply were prepared in order to study the performance of the DMA system.

The length of classification area, the diameter of the central and outer electrodes were 160, 20 and 55 mm, respectively. The efficiency of the proposed DMA in particle classification was in the range of 71.9 - 92.4 % for particles in the range of 500 - 600 nm and 300 - 350 nm, respectively. Each range of particle size leave the equipment with maximum efficiency at a specific voltage.

By knowing the peak voltage for a particular particle size, the size distribution of the unknown particles can be determined by this device. The good performance and wide range of particle size distribution are the capabilities of the proposed DMA in this study.

Cement factory workers exposure to airborne particles containing crystalline silica in Portland cement chemical compound can caused pulmonary diseases, including silicosis and lung cancer. The aim of this study was to assess the risk of occupational exposure to respirable cement dust and crystalline silica in a cement factory in Khorasan Razavi province.

In this cross-sectional study conducted in 1397, the method presented by the Institute of Occupational Safety and Health of Singapore was used to assess the health risk of respirable cement and silica particles. Also, the standard method MDHS101 / 2 recommended by NIOSH was used to determine the concentration of respirable cement particles in the air of the workerschr('39') respiratory area and the X-ray powder diffraction method (XRD) was used to determine the concentration of inhalable crystalline silica particles. Stata software version 14 was used for statistical analysis of data.

This study showed that most of the workers employed in various worksites of the cement factory were exposed to respirable cement dust and crystalline silica particles higher than the OEL recommended by the Iranian TCOH and the TLV recommended by ACGIH. Exposure risk assessment in different parts of cement factory showed a low risk level for respirable particles of cement in the furnace and moderate for other sections. Also a high risk level for workers’ exposure to crystalline silica was found in the cement mill and very high level for workers in other sectors.

Employees who were working in this plant were exposed to moderate risk of cement respirable particles and high risk level of exposure to crystalline silica. Thus, the engineering control methods of exposure to respirable particles is suggested.

Determining the size distribution of the particles for assessing their effects on human health and their control mechanisms is very effective. One of the most important equipment used in determining particle size distribution is the DMA. In this study, in addition to the design and construction of a DMA, the size distribution measurement of aerosol particles was carried out.

In this experimental-laboratory study, according to the theoretical principles, the geometric dimensions and operating conditions of the DMA were determined by Fortran programs. The design of the technical drawing of the DMA was done using the Salidworks-2017 software. The DMA designing was performed by studying the size distribution of 12 ranges of DOP particles in 15 voltages.

The results of applying different voltages to the DMA showed that one range of particles size had the highest number of particles in the output of the DMA at each voltage. As the number of particles with the size of 0.26-0.3 µm at 3500 volts and those larger than 2 µm at 9000 volts is the highest at the output of the DMA.

DMA systems are a robust tool in determining the particle size distribution. As by knowing the required voltage to separate a specific size of the particles, the DMA will be able to specify the spectrum of unknown particles.

The revised National Institute for Occupational Safety and Health (NIOSH) lifting equation (RNLE) is commonly used for risk assessment of manual handling, and can estimate low back pain (LBP) biomechanical stressors of lifting and/or lowering of loads. The aim of this study was to evaluate manual material handling by using the RNLE, LBP, and LBP disability index (LBPDI) among workers in a tile and ceramic industrial unit in Tehran, Iran. A sample of 30 workers (manual workers) in a tile and ceramic production line was recruited. Low back pain prevalence and disability index were measured using body map questionnaire combined with visual analog scale and self-report Oswestry disability index (ODI), respectively. Statistical data analysis was done using SPSS software, version 22. According to results, composite lifting index was 14.77. Low back pain prevalence among workers was reported equal to 100%; also, Low back pain intensity was equal to 68.8 ± 17.8. The mean of Low back pain disability index among workers has been reported equal to 41.3 ± 17.1 (severe crippled). The results show that composite lifting index value for these jobs exceeded 3, which means that there is a significant level of physical stress associated with these jobs for nearly all workers. Both strength and endurance for this job are high; therefore, job redesigning could decrease the physical demands, Low back pain prevalence, and Disability index, through modifying the job layout and work stations.

Knowledge of the relationship between risk levels and occurrence of events is one of the important elements in the development and implementation of programs to prevent the occurrence of accidents. The aim of this study was to assess the risk of jobs in container operations, and investigating the correlation of its results with accidents performance indicators.
This cross sectional and descriptive-analytical study was carried out in one of container terminals in southern of Iran in 2016 - 2017. Failure Mode and Effects Analysis (FMEA) were used for risk identification and assessment. Accident Frequency Rate (AFR), Accident Severity Rate (ASR) and Frequency-Severity Index (FSI), were calculated. Data analysis was performed using the SPSS version 18 software.
According to the results, 2, 56.19 and 24.8 percent of identified risks were reported as acceptable, tolerable, and intolerable, respectively. The mean of Risk Priority Number (RPN), AFR, ASR and FSI were equal to 171.26, 68.6, 400.1, and 1.84, respectively. Statistical significant relation was found between RPN, AFR, ASR, and FSI, as according to linear regression model for one unit increase in the RPN, the FSI, ASR, and AFR, the intensity has increased 0/064, 3.08 and 1.15 units, respectively.
High levels of accident indicators and intolerable risks, as well as a significant relationship between the results of risk assessment and accident indicators, indicate weakness of the safety system in container operations. Therefore, the establishment of an effective safety system is necessary to improve safety and eliminate its noncompliances.

Musculoskeletal disorders (MSDs) are the most common problems in workplaces. The present study assessed the prevalence of musculoskeletal disorders and the level of risk for these disorders among workers of an aluminum industry in Tehran.
In this cross-sectional study, Nordic questionnaire was used in order to assess musculoskeletal disorders among all workers in production line of the mentioned industry (82 workers) and to determine musculoskeletal disorders risk levels, workers’ body posture was assessed by REBA (Rapid Entire Body Assessment) and QEC (Quick Exposure Check) techniques. Statistical analysis was conducted using Chi-square test and through SPSS16 software.
According to the results, 83.9 percent of the subjects have complained from pain in at least one of ​​their body areas during the past year. The highest prevalence of disorders was respectively allocated to the low back (48.2%), knee (35.7%) and wrist/hand (33.9%). The prevalence of musculoskeletal disorders showed significant correlation with age, job experience and BMI. But, REBA and QEC final scores had no significant correlations with the prevalence of musculoskeletal disorders. According to REBA and QEC, respectively 43.6 and 67.2 percent of postures were categorized in high and very high risk levels.
High prevalence of musculoskeletal disorders and levels of risk, prioritize the necessity of corrective actions. Higher percent of high risk level in QEC than REBA can be attributed to the capability of this tool in combined investigation of work posture, work related risk factors and mental disorders affecting the incidence of these disorders.

Musculoskeletal disorders (MSDs) have been reported as the most importantreason for early retirement among dentists. The aim of this study was to assess the prevalence of musculoskeletal disorders and body discomfort among dentists. This cross sectional and descriptive-analytical study carried out on all dentists(150 subjects) of one of universities in Tehran province. We useda visual analog scale (in order to determine the severity of body discomfort) and also a body mapquestionnaire (in order to assess musculoskeletal disorders prevalence). Data analysis was performed using the Mann-Whitney test, t-test and Kruskal-Wallis.Statistical analysis was conducted using SPSS version 22 software. According to the results of the body map questionnaire, the highest prevalence of musculoskeletal disorders was allocated to the neck (50%), shoulder/arm (45.3%) and low back (34.5%), respectively. Also results of the visual analog scaleindicated that the highest amount of discomfortwas related to low back (70.2), neck (55.4) and shoulder/arm (54.4), respectively. According to high prevalence of musculoskeletal disorders and also, high levels of body discomfort, dentists need to take corrective actions with the priorities of educational programs.