Journal of Occupational Hygiene Engineering
Year:2015 | Volume:2 | Issue:4|Papers Count:8

Introduction: Steel industries are one of the major needs of the country. Noise pollution in steel production operations is an occupational hazard because of special equipment such as electric arc furnaces. The aim of this study was to evaluate noise pollution in various units of a steel company for determining the occupational exposure pattern.Methods: This was a cross-sectional and analytical noise pollution study in various units of a steel company in Iran (Hamadan state). The sound pressure levels were measured in accordance with the ISO-9612 standard and using the Casella-Cel model 450 sound level meter on “A” frequency weighing and the “slow” mode for time response. The frequency analysis in one octave-band was done with measures on “C” frequency weighing. We used the Surfer V.10 software for interpolation and noise maps producing. Microsoft Office Excel 2010 software was used for graph drawing. Noise dosimetry was performed using model TES-1345 dosimeter.Results: The results of this study showed that 56% of the total measurement stations were in the danger zone [above 85 dB (A)]. The maximum sound levels in the areas of electric arc furnaces and ladle furnace were recorded 112.2 dB (A) and 97 dB (A), respectively. The averages of the noise dose in three occupational groups of industrial cleaner, melting and casting were 2133%, 514%, and 577%, respectively. The dominant frequencies recorded in two central frequencies were 125 Hz and 250 Hz, respectively.Conclusions: According to the results, occupational exposure to noise in all the units indicated a dominant frequency of less than 500 Hz and could not be protected by hearing protection devices. The noise doses were over 500% and the time exposure shifts could not be reduced. Therefore, performing technical control plans are of priority in this industry.

Introduction: Benzene, Toluene, Ethylbenzene and Xylenes (BTEX) are important parts of the volatile organic compounds (VOCs) family, which are widely used in many industries. These have been classified as carcinogenic compounds and the neurotoxic effects of BTEX have been reported; so, a screening evaluation of workplace air quality for determining BTEX may seem necessary.Methods: In order to measure the workplace concentrations of BTEX in the hydrometallurgical process, six sampling stations were selected. Volatile organic compounds were analyzed using the method 1501 of the National Institute for Occupational Safety and Health (NIOSH). Activated carbon was used for sampling and samples were analyzed by gas chromatography with flame ionization detection (GC-FID).Results: The highest measured levels were observed for ethylbenzene at sampling station 1 (0.8 ppm). The concentration of benzene in this sampling location was 0.05 ppm. The highest toluene concentration was reported at sampling station 4 (0.15 ppm) and the lowest toluene concentration was 0.02 ppm at sampling station 6.Conclusions: Indoor air quality in workplaces can be affected by the presence of BTEX. The results of measurements of BTEX showed low concentration levels of these compounds in the studied workplace.

Introduction: Risk assessment of hazardous processes is the priority of risk management. Layer of protection analysis (LOPA) is one of the most popular methods used for risk assessment. Due to the insufficient information or uncertainty in failure rates (PFD) of protective layers, risk assessment based on the conventional LOPA can result in error in calculations. In this study, we tried to use the fuzzy set theory to evaluate the ammonia receiving tank safety, using the LOPA method.Methods: Initially, the fuzzy failure rate of protective layers were calculated using the subjective opinions of professionals. Then, by applying the fuzzy operators, fuzzy possibilities transformed to fuzzy probabilities and subsequently they were deffuzified to crisp failure rate. Afterwards, using the severity fuzzy logic, severity of the outcome event was calculated in the fuzzy form, and subsequently, fuzzy risk index was calculated using the fuzzy matrix.Results: In the ammonia release scenario, calculated severity, probability and risk levels were determined as P: Low, S: High, and R: TNA, and PF=-2.66, SF=3.99, RF=3.79 (0.2 TNA, 0.8 NA) for classic and fuzzy LOPA methods, respectively. In addition, after inserting additional layers of protection, the fuzzy risk index reduced from 3.79 (0.2 TNA, 0.8 NA) to 1.92 (0.1 A, 0.8 TA, 0.1 TNA).Conclusions: In the condition of uncertainty and lack of information relating to probability and severity of risk scenarios, the experts’ opinions can be used in forms of linguistic variables and fuzzy relations to reduce calculation errors in risk assessment as much as possible.

Introduction: This study aimed to investigate the effect of carpet weaving at a proposed workstation on Upper Trapezius (UTr) fatigue during a task cycle. Fatigue in the shoulder is one of the most important precursors for upper limb musculoskeletal disorders. One of the most prevalent musculoskeletal disorders between carpet weavers is disorder of the shoulder region.Methods: This cross-sectional study, included eight females and three males. During an 80-minute cycle of carpet weaving, Electromyography (EMG) signals of right and left UTr were recorded by the surface EMG, continuously. After raw signals were processed, MPF and RMS were considered as EMG amplitude and frequency parameters. Time series model and JASA methods were used to assess and classify the EMG parameter changes during the working time.Results: According to the JASA method, 58%, 16%, 8% and 8% of the participants experienced fatigue, force increase, force decrease and recovery, respectively in the right UTr. Also, 50%, 25%, 8% and 16% of the participants experienced fatigue, force increase, force decrease and recovery, respectively in the left UTr.Conclusions: For the major portion of the weavers, dominant status in Left and right UTr was fatigue, at the proposed workstation during a carpet weaving task cycle. The results of the study provide detailed information for optimal design of workstations. Further studies should focus on fatigue in various muscles and time periods for designing an appropriate and ergonomics carpet weaving workstation.

Introduction: Taxi drivers’ exposure to repeat whole-body vibrations can cause back pain and digestive disorders. Since this type of vibration depends on the car components, this study was carried out to determine the influence of tire characteristics on the amount of whole-body vibrations transmitted to the Peugeot 405 taxi drivers.Methods: In this experimental study, vibration characteristics were measured according to the ISO2631-1 with each of the statuses: tubeless tires fixed and fluid in it (normal air or nitrogen) and also the fluid in the tires fixed with tubes or tubeless on asphalt-paved road. Other variables including tire pressure, engine speed, road gradient, number of passengers, springs, and shock absorbers were kept constant. Then the effect of changes was analyzed using an appropriate statistical test.Results: After changing nitrogen to normal air and tubeless tires to tube, the average of RMS in Z-axis, eight-hour equivalent acceleration A (8) and crest factor were reduced (P<0.05). Also, A (8) reduced from health risk zone (>0.9 m/s2) to caution zone (0.45-0.9 m/s2) with a value of 0.8 m/s2.Conclusions: The amount of vibration transmitted to the whole body is sensitive to existence of tubes and tires inflation so that we can reduce the amount of whole-body vibration to lower than the upper limit of the health risk by changing the characteristics of the tire.

Introduction: Human errors are the cause of many accidents, including industrial and medical, therefore finding out an approach for identifying and reducing them is very important. Since no study has been done about human errors in the dental field, this study aimed to identify and assess human errors in postgraduate endodontic students of Kerman University of Medical Sciences by using the SHERPA Method.Methods: This cross-sectional study was performed during year 2014. Data was collected using task observation and interviewing postgraduate endodontic students. Overall, 10 critical tasks, which were most likely to cause harm to patients were determined. Next, Hierarchical Task Analysis (HTA) was conducted and human errors in each task were identified by the Systematic Human Error Reduction Prediction Approach (SHERPA) technique worksheets.Results: After analyzing the SHERPA worksheets, 90 human errors were identified including (67.7%) action errors, (13.3%) checking errors, (8.8%) selection errors, (5.5%) retrieval errors and (4.4%) communication errors. As a result, most of them were action errors and less of them were communication errors.Conclusions: The results of the study showed that the highest percentage of errors and the highest level of risk were associated with action errors, therefore, to reduce the occurrence of such errors and limit their consequences, control measures including periodical training of work procedures, providing work check-lists, development of guidelines and establishment of a systematic and standardized reporting system, should be put in place. Regarding the results of this study, the control of recovery errors with the highest percentage of undesirable risk and action errors with the highest frequency of errors should be in the priority of control.

Introduction: noise pollution has a negative effect on physiological parameters, efficiency and auditory system. The aim of this study was to evaluate the performance of a sound screening method for estimating sound risk in small workshops of Hamadan city.Methods: This cross-sectional study was conducted in 22 plants with more than 20 workers. Noise screening was done using a screening form. Next, noise level was measured at all the plants by SL 4001 sound level meter and regular grid method. Data were analyzed using Pearson’s test and linear regression by SPSS version 16 software.Results: The mean (SD) scores of sound pressure level and screening form were 80.12 dB (7.277) and 60.50 (8.964) in the 22 understudy plants, respectively. The average measured workshop area and volume were 1448 and 10300, respectively. Pearson’s test revealed a significant relationship between the results of the two methods, (P<0.046). Also the percentage of workers at risk (greater than 85 dB) was 32.29 and the percentage of workers within safe limit (less than 85 dB) was 63.3. While the largest percentage of workers in the caution zone (82 dB) was 67.04.Conclusions: A correlation was shown between the results of the two methods. The use of this method to identify workshops with the possibility of noise pollution is effective.

Introduction: Occupational exposure to Extremely Low Frequency Magnetic Fields (ELF-MFs) in train drivers is an integral part of the driving task and creates concern about driving jobs. The present study was designed to investigate the occupational exposure of Tehran train drivers to extremely low frequency magnetic fields.Methods: In order to measure the driver’s exposure, from each line, a random sample in AC and DC type trains was selected and measurements were done according to the IEEE std 644-1994 using a triple axis TES-394 device. Train drivers were then compared with national occupational exposure limit guidelines.Results: The maximum and minimum mean exposure was found in AC external city trains (1.2±1.5 mT) and DC internal city trains (0.31±0.2 mT), respectively. The maximum and minimum exposure was 9 mT and 0.08 mT in AC trains of line 5, respectively. In the internal train line, maximum and minimum values were 5.4 mT and 0.08 mT in AC trains.Conclusions: In none of the exposure scenarios in different trains, the exposure exceeded the national or international occupational exposure limit guidelines. However, this should not be the basis of safety in these fields.