سال:1390 | دوره: | شماره: |تعداد مقالات:8

Roadside noise barrier as the noise control solution is extensively applied to reduce noise pollution. Median barrier like roadside barriers can make insertion loss at the receiver’s area making a shadow zone behind the screen. However, the performance of roadside barrier can be affected by erecting a median barrier. Mainly a median barrier is considered as an extra structure to decrease the cross median crashes at highways. The aim of this study was to investigate the effectiveness of some treatments such as absorbent material and diffusers on various median barriers shapes. A 2D boundary element method was used to analyze the designed median barrier effects. Application of grass on the top surface of median barriers with even cap was more effective than those median barriers that had uneven cap. Utilizing Primitive Root Diffuser (PRD) and Quadratic Residue Diffuser (QRD) on the stem surface of median barrier has high efficiency due to cancel outing multiple reflection effects between roadside barrier and median barrier by 2.2 to 2.7 dB (A), while no improvement could be seen at median barriers with QRD and PRD tops. Finally, it can be stated that the performance of most median barriers were increased using the reactive surfaces on the stem sides of the barrier, while the top surface treatment was not very effective in this kind of screens.

At present, conventional methods of noise exposure assessment utilize in industrial workplaces. In the classical area assessment method, noise exposure assessment depends on sound pressure level measurement results that expressed numerically and indicated harmful areas. This paper proposes an exposure assessment method of occupational noise based on Fuzzy sets. The noise assessment by Fuzzy logic method involves the primary investigation of the workplace, determined inputs and output variables, Fuzzification, Fuzzy rules, Fuzzy inference method and Defuzzification. This assessment method considered a function consists of Noise level, the number of exposed workers, exposure duration and noise reverberation time. Suggested method makes possible to evaluate unconsidered cases in order to assess of noise exposure risk. Fuzzy logic assessment results are more useful and flexible for analysis than conventional assessment. Fuzzy logic provides the opportunity to obtain risk model of noise exposure based on noise parameters, dimension of workplace and human perceptions.

Occupational exposure to carbon monoxide (CO) of taxi drivers has seldom been evaluated in Iran. Accordingly, in-vehicle CO levels were evaluated during 6 months inside the taxis between May 2009 and October 2010. The CO concentrations of 36 personal samples were collected using a direct reading instrument equipped with electrochemical sensor. The arithmetic mean of the personal monitoring CO levels was 19.84±4.24 ppm per day, with a range of 13.29-33.46 ppm. The observed concentrations of CO fell well lower than occupational standards. Exposures to CO during traffic flow in the evening were considerably higher than those measured in the morning. The weekdays, months and atmospheric environment had a significant effect on exposure to CO (p<0.0001). The average CO level was 19.84±4.24 ppm, which was higher than the outdoor CO levels (3.21 ppm). In conclusion, the penetration of outdoor CO pollution and engine combustion/exhaust infiltration constituted the main sources of the taxis drivers' personal exposure to CO.

 Exposure to air pollutants is significantly associated with health risks ranging from bronchial reactivity to morbidity and mortality. However, the precise mechanisms are not always fully understood. The aim of this study was to investigate the effects of sulphur dioxide (SO2) on cell viability and cytokine production of A549-human pulmonary epithelial cells. Test atmospheres of SO2 were generated using a direct dilution method and calibrated by ion-chromatography. Test atmospheres were delivered to lung cells cultured on porous membranes (0.4 mm) using Harvard Navicyte horizontal diffusion chamber systems. The cytotoxic endpoints were investigated using the MTS (tetrazolium salt, Promega), NRU (neutral red uptake, Sigma) and ATP (adenosine triphosphate, Promega) assays. Expression of inflammatory markers including tumor necrosis factor-a (TNF-a) and interleukin-6 (IL-6) were evaluated using double-antibody immunometric assays. Dose-dependent effects of SO2 were observed in A549 cells using all in vitro assays at test concentrations (10-200 ppm). The ATP assay appeared to be the most sensitive test (IC50=48±2.83 ppm) that may related to the impaired metabolic activity of the cells following SO2 exposure. After analysis of TNF-a, no statistically significant differences were observed between control and exposed cells. However, the IL-6 production in A549 cells was significantly reduced in a dose-dependent manner (p<0.05). These results suggest that SO2 may induce a functional alteration of cells of the pulmonary epithelial preventing cells to produce adequate amounts of IL-6. IL-6 as a multifunctional proinflammatory cytokine may regulate cellular responses and plays a significant role in inflammation and tissue injury.

This paper discusses empirical research aimed at investigating the most important dimensions of safety climate from Emergency Medical technician’s perspective. Investigation was conducted through the safety climate questionnaire (SCQ) in Tehran Emergency Organization. After a literature review, a 21-item questionnaire was developed and administered to 600 technicians. In order to indentify the structure of safety climate Factor analysis was used with varimax rotation method using SPSS 17 software. Data on safety climate were collected by completed questionnaire from 266 technicians with a response rate of 44%. Safety climate attributes were conducted to reduce by Factor analysis and identified five critical safety dimensions which together explained 61% of the total variance. One way ANOVA results show that there were no statistically significant differences for characteristics such as age, experience and job category at the 5% significance level. Employees’ perceptions on the five safety climate dimensions differ significantly among the four groups on the basis of their factor scores in safety climate dimensions at the p<0.05 significance level. In order to improve safety climate, based on the study results, more attention should be paid to safety training and management support.

Styrene (ethylbenzene) is widely used as a solvent in many industrial setting. Occupational exposure to ST can result in pulmonary toxicity. For better understanding of the mechanism by which styrene caused lung injury, this study was undertaken to investigate the effect of styrene on rat respiratory epithelial cells. The role of vitamin C (Vit C) on styrene induced toxicity was also investigated. Adult male rats were given ST (ip) at doses of 0, 200, 400 or 600 mg/kg. Another series of rats were pretreated with Vit C (300 mg/kg, ip) 30 min prior administration of various doses of ST. 24 h later, animals were killed with overdose of sodium pentobarbital. Lung and trachea tissues were removed, fixed and processed for light microscopy. Results demonstrated that styrene induced dose-dependant injury in respiratory epithelial cells. The antioxidant, Vit C protected cells against styrene toxicity. The results support the view that generation of oxidative stress is responsible for ST-induced damage in respiratory airway. The finding that Vit C has potential to protect respiratory epithelial cells against ST toxicity further support this hypothesis.

The main purpose of this article was to describe the concept of Kansei and its status in ergonomics, to specialists of disciplines such as safety, industrial engineering, and specifically the associates of ergonomic design of products and industrial designers. During last decades the dominate approaches of ergonomics were mainly focused on physical aspects of human body, but along with the development of sciences, it has had a dramatic growth in human mental characteristics and has expanded from physical to cognitive, aesthetic, and recently affective domains. This study includes two parts of descriptive and review study. In the descriptive phase the scopes of ergonomics and its new approaches were focused, while in the review part by choosing the appropriate keywords, the published articles in three scientific databases were searched in the context of subject. In addition, in the basis of obtained data with an emphasis on the relevancy of ergonomics and Kansei Engineering, the position of Kansei Engineering in the growing discipline of ergonomics has been analyzed due to the authors’ perspective. In this study, recent trends in ergonomics approaches and some concepts of cognitive ergonomics and its relationship to Kansei were considered.

Anthropometric data are used for proper design of workstation, equipment, furniture. Mismatch between anthropometric dimensions and consumer products may cause health problems in human body. In this study we measured anthropometric dimensions of Iranian university students in order to create a data bank for furniture design. The purpose was to measure some anthropometric dimensions of university students for furniture design. In this cross-sectional study, we measured 20 anthropometric dimensions of 911 university students aged 18-25 years (475 males and 436 females) in Iran. Their mean age (± standard deviation) was 20.45±1.24. Mean±SD weight was 70.14±12.44 kg and 58.10±8.63 kg in males and females, and mean±SD height was 1741.89±63.09 mm and 1594.91±59.88 mm, respectively. All dimensions measured were significantly different between two genders except for buttock-knee length. This study showed a significant difference between anthropometric dimensions of our population with other populations.