International Journal of Occupational Hygiene
Volume:13 Issue: 1, Mar 2021

The first aim of this study was to synthesize poly vinyl chloride (PVC) nanocomposites, consisting of various additive nanoparticles, including Silica, Zinc oxide (ZnO), and Zeolite A nanoparticles. The size of Silica, ZnO, and Zeolite A nanoparticles were near 30±2, 45±5, and 100±5 nm, respectively. The second aim was to investigate the effect of these nanoparticles on sound absorption, density, heat change, expansion, and contraction. This study was an experimental one . In this study, three nanoparticles were used, including Silica, ZnO, and Zeolite A. This study showed that PVC/Silica: 0.51%, PVC/Silica: 0.29%, PVC/Zeolite A: 6.1%, and PVC/Silica: 0.51% had the highest sound adsorption coefficient at frequency of 250, 500, 1000, and 2000 Hz, respectively. Moreover, the increase of Zeolite A and ZnO nanoparticles led to increase of density. In case of Silica nanoparticles, the increase of content of nanoparticles led to decrease of density. The heat change experiment showed that the increase of Zeolite A led to decrease of heat change, but the increase of Silica led to increase of heat change. It was found that PVC/Silica: 0.51% had minimum contraction and expansion. Taken together, PVC/Silica: 0.51%, PVC/Silica: 0.29%, PVC/Zeolite A: 6.1%, and PVC/Silica: 0.51% nanocomposite had highest sound adsorption coefficient at frequency of 250, 500, 1000, and 2000 Hz, respectively.

Today, the use of mobile phones has become an integral part of human life. With the increase of mobile phone subscribers, the number of BTS antennas in cities and villages has increased day by day, and as a result, the exposure to microwave waves from these antennas has become a concern. The study of the horizontal pattern of microwave radiation from BTS antennas with respect to the type of antennas and surrounding buildings is examined in the city of Maragheh in East Azerbaijan Province. The required information was determined through the city telecommunications organization and field monitoring. Then the measurements were performed with SPECTRAN 4060 according to IEEE STD C95.1 standard method. Data analysis was performed with SPSS software and Kolmogorov-Smirnov tests and Mann-Whitney test. In this study, the type of operator has an effect on the results and according to the type of operator, different results were obtained on the effect of the type of buildings around the antennas and the type of installation on the amount of wave propagation. Antenna installation in a crowded area due to more microwave radiation need more attention. All measurements were much lower than the ICNIRP allowable limits.

The aim of this article was to present a model for measuring and managing the risk of using hot mineral spas, based on structural safety with environmental approach. A conceptual model of risk was prepared in four stages: 1) determining the general outline of the model, 2) identifying spa structure safety indicators, 3) evaluating and scoring the indicators and 4) determining the quantitative and qualitative categories of the model and providing solutions. In this study, 30 spa structure safety indicators were extracted, and the weight of each indicator was obtained based on the amount of risk for users. Moreover, a questionnaire was prepared by analytic hierarchy process analysis method. According to the standard level allowed for each indicator, spa structure safety risk categories were prepared in five ranges for each indicator based on the obtained weights and the opinions of health experts. The results of the risk associated with each spa were obtained by combining 30 spa structure safety indicators. To assess the risk of using hot mineral spas by the method invented in this study, first, the extracted model indicators were scored in six spas of Iran. Then, risk level of the six spas was evaluated. According to the risk scores, hot spas named Gavmishgoli and Qotoursoo had an unacceptable level of risk. Qinarjeh, Shabil, and Sabalan had a high level of risk. Borjloo had a moderate level of risk. The proposed risk model provides a framework for a standard and safe mineral spa.

Air dispersion modeling is important tools to improve air quality. The primary objective of this research was focused on simulation of CO emission from stacks in Tehran oil refinery, which is main refinery complex in Iran. This study was performed by AERMOD to simulation the CO dispersion emitted from stacks in 2018 and 2019 .Modeling results shown that maximum concentration of CO values at 1hr and 8hr for two times hot and cold 109 μg/m3, 32 μg/m3, 360 μg/m3, 254 μg/m3 respectively. Simulated values of CO emissions were compared with those obtained area measurement campaign at 4 receptors. Maximum concentration of CO in cold times was more than hot times. This can be attributed to low air turbulence. Our analysis demonstrated that the AERMOD modeling system could be used in the air quality simulation in the near future for CO. Simulation output depict that were all centered in against mountain and  the middle of simulation area where the emission sources concentrated, and it is probably because the air pollutions were topography and source oriented. Finally, study results indicate that the simulated concentration of CO based on AERMOD, does not exceed concentration limit, set by the Iranian Ambient Air Quality Standard. It verified that co release from oil refinery stacks don't have any significant impact on nearby communities.

Manual load handling is a work activity related to low back disorders and can impose a high mechanical load on the lower back. The present study aimed to investigate forces exerted on the lower back during manual handling in young workers in selected block maker workshops. This Descriptive, cross-sectional study was carried out on 40 young workers with an average age of 31 years in several block maker industries in 2020. 3DSSPP Software was used for biomechanical analysis of the forces exerted on the lower back. Prevalence of musculoskeletal disorders was assessed using the Standard Cornell Questionnaires. To analyze the data from SPSS19 software and Spearman, Friedman and ANOVA correlation tests were used to determine the relationship between demographic variables and the prevalence of musculoskeletal disorders and the relationship between the prevalence of musculoskeletal disorders and the amount of compressive and shear forces on workers' backs. The results showed that the mean compressive and shear forces exerted to the lumbosacral joint (L5 / S1) were 3194.8±1064.4 and 473.2± 89.5 N, respectively, and for the intervertebral disc (L4 / L5) were 3924.8±434.9 and 383.2 ±154.5, respectively The findings also indicated that the highest prevalence of pain was related to the lower back and right knee with 45% and 30%, respectively. The direct relationship exists between the mean score of musculoskeletal disorders obtained from the Cornell questionnaire with age, work experience and weight and body mass (0.001> P). The shear forces exerted to the lower back were higher than the permissible levels in about 30 to 37% of people and the compressive forces were on average in 42.5% of people, which can cause a lot of injuries to the back in the long term. The results obtained according to the study population show that manual load handling for these ages is dangerous and in the future and at older ages, people may suffer serious injuries and disorders, especially in the lower back.

Infrastructure is important in a neighborhood that can be observed through survey conducted by independent people who are not part of that neighborhood. The present study aimed to determine well organized survey to list well defined infrastructures in neighborhoods that fulfills basics needs of neighborhoods’ people to ensure safety. A safety and engineering related survey has been conducted to identify infrastructure problems in an undeveloped neighborhood. The studied neighborhood has lacked so many modern and updated infrastructures. NNS (Near Northside) neighborhood infrastructure is failing or becoming older because of lack of engineering and safety knowledge among the community people to have awareness to improve the infrastructure. There exists a need to understand the infrastructure deficiencies that currently is apparent within the community of Near Northside. This work addressed those issues and would encourage the people to have a better infrastructure which could help to improve their neighborhoods.

With all technological advancements in production technology and robotics, a considerable amount of manual tasks are yet performed by workers. In consequence, the occurrence of that musculoskeletal disorders (MSDs) is an expected common result of manual tasks. Fatigue is one of the common causes which leads to MSDs [1] hence one of the strategies for resolving this issue is to let workers have enough rest allowances to recover from the physiological consequences of exertion. This study aims to suggest well-timed rest allowances in the MAPNA factory (Iran, Tehran). For this purpose, we designed an experiment in a workstation to obtain input data (postures and forces) and used collected data to simulate the working condition for all workers with help of 3DSSPP software. We considered maximum voluntary contraction (MVC) of involved muscles. With all this, the critical muscle was determined for all workers based on specific tasks that they performed in their station. With the help of the Rohmert model, the rest time was calculated for the critical muscle of each worker. The results present worker and task-specific optimal work time and subsequent rest time to prevent MSDs. This approach was used because statistical analysis would highlight workers and tasks which are significantly effective on rest times (for both sources p-value was less than 0.05). This approach can be used for any workstation to suggest well-timed rest allowances.

Ultrasonic testing (UT) for medical examination as well as metal flaw detection is a popular method. From the beginning of ultrasonic testing Mulhauser in 1931 lot of new things and technologies emerged in UT testing. This review paper deals with progress in detecting human organs as well as materials flaws and future prospects of UT for metal flaw detection. Study on components of UT system is conducted. Then typical UT inspection system is determined. After that advantages and disadvantages of UT have been reviewed. Major types of waves in ultrasound with considering UT instruments have been reviewed as well. Progress in different areas of UT have been discussed extensively with more emphasis on progress in composite piezoelectric materials, variations of probes, EMAT (Electromagnetic Acoustic Transducer), focused probe, focusing axicon probe, focused phased arrays, LASER(Light Amplification by Stimulated Emission of Radiation) generation of ultrasound, acoustic holography and ultrasonic microscopy. At the end future prospects of UT have been reviewed as well as recommendation has been provided.