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BACKGROUND: Noise is a common harmful physical factor in the work environment. OBJECTIVE: This study sought to prioritize noise control methods using the analytical hierarchy process (AHP) in a tire factory. METHODS: The study, which adopted a cross-sectional, descriptive, analytical design, was conducted in the baking hall of an Iranian tire manufacturing factory in 2018. 4 criteria (namely implementation and maintenance cost, method applicability, method effectiveness and efficiency, and intervention in the process) and 8 alternatives (including reducing individuals’ noise exposure time, designing and installing sound isolation chamber for operators, using of earmuffs and earplug simultaneously, changing processes or operational procedures in machinery with excessive noise generation, forming noise control engineering teams, requiring people in charge to quickly fix the leaks and change baking press washers on time, using acoustic panels in the ceiling and walls, and designing and manufacturing silencer and nuzzle for the steam and compressed air outlet of baking press machinery) were selected. Then, to prioritize noise control methods based on objectives, criteria, and alternatives, an AHP questionnaire was developed and completed by domain experts and noise control specialists. Data analysis was performed using Expert Choice V. 11 and Excel. RESULTS: The results showed that the inconsistency rate in all cases was less than 10%, hence the consistency of responses was approved. Based on experts’ opinion about the selected criteria, “implementation and maintenance cost” had the highest weight (0.481), while “method effectiveness and efficiency” recorded the lowest one (0.046). With regard to the alternatives, “change in the process” registered the greatest weight (0.193), whereas “individuals’ noise exposure time” had the lowest weight (0.046). CONCLUSIONS: Based on the final weights, the most appropriate noise control methods in this industry are changing processes in machinery with excessive noise generation, forming noise control engineering team, and manufacturing silencer and nuzzle for the steam and compressed air outlet of baking press machinery. Furthermore, AHP is a suitable approach for prioritizing decisions related to noise control.

Aims: Since the occurrence of hazards in the steel industry has often been multiple and complex, the aim of this study was to identify the risk assessment in this industry in order to study the roots and realities of the risks and the causes of their occurrence, as well as to find solutions to reduce these risks. Instruments & Methods: This descriptive-analytical research was conducted in the cement industry in Khorasan Razavi in 2017. FMEA and AHP methods were used to determine the most important safety hazards. The Risk Priority Number (RPN) was obtained from the multiplication of 3 factors including severity, probability of occurrence, and probability of discovery. Risk tolerance was used for the acceptable and unacceptable risks in the FMEA method. Findings: The fluctuation of the flange and its breakage due to excessive water pressure in the furnace and lack of lighting for installation of the equipment in the furnace had a high risk. In the AHP method, the risk of breaking the flange was due to excessive water pressure in the furnace and lack of lighting to install the equipment in the furnace, which had a higher weight than the other hazards. Conclusion: Although in the developing countries, the use of risk analysis methods with a preventive approach is not common, these problems have been resolved by communicating with the industry by recent studies. It also emphasizes the use of decision-making methods to minimize the impact of judgments on risk assessment.

Background and aims: Nowadays, artificial insulators such as fiberglass and rock wool are used as sound absorbers in developing countries. The present study is performed to introduce new sound absorbing materials used in developed countries and discuss their acoustical characteristics. It also aims to look at the efficiency of sound absorber natural materials (green materials) as an alternative to commercial materials with a synthetic base used in different places. Methods: In order to identify new porous absorbents, their mechanism of action and various applications, a search was conducted by using keywords such as “Sound Absorbent”, “Natural Noise Absorbent” and “Passive Absorber” in PubMed, Scopus, Science Direct, ProQuest, Springer, Web of Knowledge, Magiran, SID, IranMedex and Google Scholar. We selected 48 review and original research papers that were about natural and recycled absorbents. Results: Most recent research includes production and optimization of sound absorbers using natural and recycled materials. The aim of all of these researches was producing green absorber materials in accordance with environmental regulations. In order to properly use these materials, in addition to knowing the benefits and suitability of absorbers for use in the intended environment, the effective factors in sound absorption such as fiber size, air flow resistance, porosity, curve, thickness and density of absorbers were considered. Conclusion: In comparison to old absorbents, new materials are safer and lighter and enjoy a more efficient technology. It seems like environmental friendly, degradable, recyclable and green noise absorbents will play on important role in the market of noise absorbents in the future. Also because of the place and different uses of absorbent materials, specialists should consider the limitations of the environment and the acoustic characteristics of the absorbents.