Journal of Health and Safety at Work

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Introduction: Each year tens of millions of labors are victims of occupational incidents leading to the disablement or death of many of them. The present study has been conducted with the aim of predicting the performance monitoring indicators of incident after implementation of the integrated management system in order to reduce number of incidents, safety monitoring, and giving priority to safety programs in the organization policies.

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Matherial and Methods: Using safety performance indicators, this descriptive-analytical study has been done in two stages in a combined cycle power plant on 254 incidents before the implementation (2004) and the years after the implementation of integrated management systems(a seven year period). The required data was gathered through checklist and interview with the injured workers. Kolmogorov-Smirnov, Chi Square, and Cubic regression tests were utilized for data analysis at significance level of 0.05.

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Results: Of the 1131 labors during a seven year period, 254 occupational incidents were recorded. The highest value of accident frequency rate was in 2004 (32.65) while the highest accident severity rate was in the year 2008 (209). Moreover, the lowest frequency rate and severity rate were related to the year 2011 with value of 9.75 and 29.26, respectively. Regression graphs, between the observed values and the estimated values, showed that the coefficients of all the indicators, except for β1of ASR,are significant(P< 0.05) as expected. This result implies the improvement in the safety performance and integrated management systems.

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Conclusion: Findings show that Cubic regression can be an appropriate to olforinvestigating the indicators trends and for their predictionin planning and monitoring the performance ofsafety unitso that the decision-making for determining the priority of organizations’ safety programs would be facilitated.

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Introduction: Efficiency of hoods for local exhaust ventilation system is influenced by hood geometry, its situation relative to the process and the air volume exhausted by it. The aim of this study was to present a simple and practical method based on the standards for assessment of potential problems of ventilation system in a steel making company.  

Material and Method: In this cross-sectional study, a checklist based on the ACGIH ventilation standards was developed for investigating potential problems related to the three types of hoods in an oxide screen process. This checklist has completed in order to feasibility study of corrective changes in evaluation of the hood hardware parameters. The differences between design and current status to the standards were considered as noncompliance. Finally, differences were analyzed statistically.   

Result: Based on statistical analysis, the average of current status of hoods, plans and design documents and standards were for variables of conveyors downstream enclosure (1.6, 2.38 and 2.41m), vertical distance from hoods to conveyors (0.39, 0.37 and 0.61m), conveyor longitudinal enclosing after hood (1.225, 1.288 and 0.296 m) and hood numbers (18, 17 and 31), respectively. Comparing the results between current status of hoods with plans and design documents showed no significant differences (0. P-value≤ 0.05). But, the results between current status of hoods and design documents with standards have significant difference (0. P-value≥ 0.05). A significant difference  (0. P-value≥ 0.05) revealed between the average of the current status of hoods, plans and design documents and the standards for variables of hood flow (813.3, 2276.9 & 3085.9 cfm) and duct velocity leading to the hoods (2289.3, 5083.5 & 3500 fpm), respectively.

Conclusion: This method can be applicable for the local ventilation systems with extensive pollution sources and hoods. One of the advantages of this method can be easily application of this system, as one of the requirements for delivering ventilation systems from contractors and the use of it for studying potential problems of the hoods that they have standards. Also, by comparing current status of hoods with the design specifications and standards, the mismatches/ unconformities in the lifetime and maintenance process of the system can be understood.

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Introduction: Protection of the respiratory system has been a vital, and for this purpose, various solutions have been proposed, including the use of masks. One of the most important parameters to measure the effectiveness of the mask against the penetration of microbial agents. The present study was conducted with the aim of evaluating the bacterial and particle filtration of medical masks.
Material and Methods: To assess bacterial performance, the national standard 6138, compliant with EN14683, and Type I medical masks were utilized. Staphylococcus aureus bacterial suspension was prepared and passed through the mask using a nebulizer and through an impactor with a flow rate of 28.3 l/min. Plates containing soy agar were placed in the impactor. Subsequently, all plates were incubated, and the bacterial filtration efficiency (BFE) of the masks was determined by counting the bacterial colonies that passed through the mask’s media as a percentage of the total bacteria. It is worth noting that the pressure drop and particle filtration efficiency were also determined for all masks
Results: Based on the results of the particle removal performance for the particle size of 3 µ, the masks were categorized into three groups with efficiency above 99%, above 95% and 90%. According to the standard, all masks had an acceptable pressure drop below 40 Pa. The acceptable bacterial filtration rate for type I masks should be above 95%. The results showed that type A and B masks have an acceptable bacterial filtration rate and there is a significant correlation between the types of masks examined in terms of bacterial and particle efficiency.
Conclusion: The results showed that different types of masks under investigation have significant differences in terms of particle capture efficiency and bacterial filtration performance. In addition, there is a significant correlation between bacterial and particle filtration efficiency.