Iranian Journal of health, Safety and environment
Volume:2 Issue: 1, Winter 2015

Workers in wood industry are exposed to vibration and its damages. The purpose of this study was to evaluate exposure to hand-arm and whole body vibration in the wood industry. In this study, the parameters of whole body and hand-arm vibrations such as effective acceleration, overall equivalent acceleration, Vibration Dose Value and crest factor were studied on two Thicknessing planes, two sliding panel saw machines, two orbital sander, and three operators of perforate procedure. Assessments were done by the use of an oscillator and an analyzer of Svantak Co. Evaluating Hand-arm and whole body vibrations were conducted based on ISO 5349-1, ISO 5349-2 and ISO 2631-1 standards, respectively, and the findings/ the evaluated data were analyzed.The mean amount of daily exposure to hand-arm vibration (RMS) in Thicknessing plane, Orbital Sander and Sliding panel saw machine operators are respectively 5.56, 5.49 and 3.37 m/s2. In addition, the average crest factor of the 3 jobs is higher than 6. Mean of daily Exposure to whole body vibration in 3 machine operators of Thicknessing plane, perforate procedure and Sliding panel saw is respectively, 0.28, 0.24 and 0.17 meters per square second. The crest factor for all the exposures was to be less than 6 and the mean of the calculated daily vibration dose equaled 5.83 with the standard deviation of 0.87(m)⁄s^1.75. In further measured situations, exposure to hand-arm vibration is more than the standard level, so engineering and management measures are required to reduce the amount of exposure and support the health of the operators and the equipment.

Detergents and problems of their attendance into water and wastewater cause varied difficulties such as producing foam, abnormality in the growth of algae, accumulation and dispersion in aqueous environments.One of the reactors was designated with 30% of the media with the similar conditions exactly same as the other which had filling rate about 10 %, in order to compare both of them together. A standard method methylene blue active substance was used to measure anionic surfactant. The concentrations of linear alkylbenzene sulfonate which examined were 50, 100, 200, 300 and 400 mg/l in HRT 72, 24 and 8 hrs.The removal percentage for both of reactors at the beginning of operating at50 mg/l concentration of pollutant had a bit difference and with gradually increasing the pollutant concentration and decreasing Hydraulic retention time, the variation between the removal percentage of both reactors became significant as the reactor that had the filling rate about 30 %, showed better condition than the other reactor with 10 % filling rate. Ideal condition in this experiment was caught at hydraulic retention time about 72 hrs and 200 mg/l pollutants concentration with 99.2% removal by the reactor with 30% filling rate. While the ideal condition for the reactor with 10% filling rate with the same hydraulic retention time and 100 mg/l pollutants concentrations was obtained about 99.4% removal.Regarding anionic surfactant standard in Iran which is 1.5 mg/l for surface water discharge, using this process is suitable for treating municipal wastewater and industrial wastewater which has a range of the pollutant between 100-200 mg/l. but for the industries that produce detergents products which make wastewater containing more than 200 mg/l surfactants, using secondary treatment process for achieving discharge standard is required.

In most sensitive occupations such as nuclear, military and chemical industries closed circuit systems and visual display terminals (VDTs) are used to carefully control and assess sensitive processes. Visual fatigue is one of the factors decreasing accuracy and concentration in operators causing faulty perception. This study aimed to find out a relationship between visual fatigue symptoms (VFS) of Flicker value variations in video display terminal (VDT) operators. This cross-sectional study, conducted in 2011, aimed to examine visual fatigue and determine the relationship between its symptoms and visual flicker value changes in 248 operators of VDTs in several occupations. The materials used in this study were a visual fatigue questionnaire of VDTs and a VFM-90.1 device. Visual fatigue was measured in two stages (prior to beginning to work and 60 min later). The data were analyzed by SPSS11.5, using descriptive statistics, paired t-test, simple and multiple linear regressions, correlation and recognition coefficients. Then regression equations of changes in flicker value depending on the changes in the main domains and the changes in final score before the questionnaire were obtained. Paired t-test indicated significant differences in the mean score of visual fatigue symptoms and the mean score of flicker value between the two stages, respectively (P ≤ 0.001). Simple and multiple regressions of flicker value variations, for the last visual fatigue changes in questionnaire score and the four main domains of the questionnaire were obtained R2 = 0.851 and R2 = 0.853, respectively. Correlation coefficient in the above tests indicated reverse and significant relationships among flicker value changes with changes in questionnaire score and visual fatigue symptoms.Diagnosing the first symptoms of visual fatigue could be an appropriate warning for VDTs operators in sensitive occupations to react suitably, in behavior and management, to control or treat visual fatigue and prevent errors efficiently.

Olang wastewater treatment facilities purifying raw urban wastewater consist of two stabilization pond modules. Both are on operation in parallel. Functioning of natural systems is influenced by different factors including ambient condition. Considering final effluent of this system discharges to Kashafrood river and sometimes is used for agricultural purposes, assessing the quality parameters in effluent was the main objective of this study. This cross-sectional study investigated some important quality parameters for both raw and treated wastewater in two years periods. Data analysis was carried out using descriptive statistics. Statistical tests were done at a significant level of 0.05. Simple linear regression analysis was used only for modeling. Raw wastewater was almost severe. Average removal efficiency for BOD5, COD, and TSS was 81, 83, and 78% respectively. There wasn’t a meaningful relationship between the removal efficiency of mentioned parameters and input pH. Ambient temperature fluctuations were effective on BOD5, and COD reduction. SAR index didn’t show a considerable restriction on irrigation application of effluent. In 62.5% cases outlet Na content was at the extent to which restrictions were imposed. Olang wastewater treatment plant generates an acceptable effluent relating to most of the quality parameters that were measured in this study. Considering special status of Mashhad city, it is worthy to reuse effluent in areas with a high water requirement such as agriculture.

A comprehensive study was conducted with the objectives of evaluation of noise exposure in the workplace of bus drivers, and to find attitudes of passengers and drivers. This study consisted of two phases. In the first phase, Noise levels were measured in fifty buses. The evaluation of noise levels in the workplace of bus drivers was performed according to the Iranian legislation`s. Twenty four buses with noise levels above 85 dB (A) consider as an "unsafe" workplace. In the second phase, the attitude of 50 male drivers and 500 passengers concerning the annoyance and impact of noise on health was also surveyed. Second phase showed that 70% of drivers and 86.4% of passengers were nervousness from high level noise inside the buses. Eighty four percent drivers and 80% passengers felt noise had affected on their hearing. This study also affirmed that out of every seven drivers, six reported headache.

Subway system is one of the critical infrastructures in a society. In economic optimizations of risk control measures, valuing the loss of life and other financial losses in terms of money on the other hand, could influence the optimal investments in safety. The purpose is to contribute to the implementation of HSE in the transportation system. In this research, a fire risk assessment along with its economic loss estimation in the Direct Current (DC) trains and rectifier substation (RS) of Tehran subway is implemented. The number of fatalities, the extent of damage on the train equipment, etc., is then calculated in monetary unit.By using Event Tree Analysis (herein ETA), after identification of initiating events through observation, interviews, and evaluation of documents, event tree was constructed for each of them and the probability of multiple scenarios were computed.The scenario with the highest probability of fire in RS, including increased heats in the RTU panels generate a loss of at least 730 Million Rials. Accordingly, the minimum and maximum economic loss caused by fire on DC trains is minimum 510 and 1230 Million Rials, respectively. Given the findings of this study, the financial and human life risks, along with all tangible and intangible losses, which is considerable, the relevant managers must compare investments in safety, with the decrease of calculated economic risks as a result of fire accident in Tehran subway.

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