Journal of Occupational Hygiene Engineering
Year:2016 | Volume:3 | Issue:3|Papers Count:8

Introduction: In some jobs, physical activity might be performed in high noise pollution, which can affect the heart rate. The aim of this study was to investigate the effects of noise exposure and physical activity on heart rate in hot and humid conditions.Methods: This experimental study was performed on 14 healthy males in hot and humid climatic chamber (35°C, 75% RH). Heart rate was measured at rest, sitting, low workload, moderate workload and heavy workload in non-noise exposure and noise exposure trials in 65, 75, 85 and 95 dBA levels.Results: In hot and humid weather conditions, there was a significant relationship in heart rate average between conditions of sitting, low, moderate and heavy workload, in nonexposure to noise and noise exposure at level of 65, 75, 85 and 95 dB (A) (P<0.05). In all activity levels, the heart rates significantly increased with increasing the sound intensity. There was more increase in heart rate in higher than the threshold limit noise level in moderate and heavy workloads.Conclusions: According to the additive effects of noise exposure on heart rate in hot and humid conditions, workload levels are considered higher in hot and humid conditions compared with thermal comfort conditions, if there is exposure to noise over 85 dBA.

Introduction: Quality and efficiency of health, safety and environment (HSE) management systems play a vital role in achieving their goals. Considering that outputs and objective achievement make continuous improvement of services and products, internal and external customer satisfaction, adopting a systematic way for performing various tasks, system performance, and analysis are very important. The present study was conducted to construct a proper framework for assessing the Iran Power Plant Projects Management Company (MAPNA) group contractors in terms of their health, safety and environment performance.Methods: In the first step of the study, all the documents and literature associated with performance assessment were reviewed. In the second step, using a focus group approach, a basic model for assessing the HSE management system was designed. Lastly, the framework was tested and credited on three major contractors of the MAPNA group.Results: The proposed framework composed of five criteria. The main criterion was the pattern of HSE process implementation, which had seven sub-criteria and 120 guiding hints. Moreover, the five criteria were able to assess the organizational capabilities in terms of health, safety and environment management.Conclusions: The proposed framework made contractors able to promote their HSE performances by identifying organizational strong and weak points, prioritizing improvement projects, and also monitoring the pace of improvement in achieving organizational excellence.

Introduction: During physical activity in hot environments, sweating with evaporation as an important physiological response of the body increases and could lead to dehydration.Long-term water shortages could adversely affect vital organs. The aim of this study was to determine heat stress and dehydration status of workers in hot workplaces.Methods: This cross sectional study was done on 90 workers of a sugar factory, which were exposed to heat. Heart rate and oral temperature were respectively measured using a heart rate meter and an oral thermometer. The WBGT index was recorded and the HSSI questionnaire was completed simultaneously, and in order to assess dehydration level a refractometer was used. Data obtained from this study were analyzed by comparing means, t test, and paired t test tests by the SPSS 20 software.Results: Heat stress exceeded the national and international recommended limits based on the WBGT index in 44% of cases of workstations. According to this study, 8.5% of the population had some degree of dehydration. Furthermore, 63.4% were significantly dehydrated (urine SG>1.020) and 28% were severely dehydrated (urine SG>1.030) and the mean specific gravity was 1.025 ± 0.043. The correlations between heat strains, urine density, and heat stress including oral temperature and heart rate were significant (P<0.05).Conclusions: A high percentage of the study population had some degree of dehydration based on the results. It seems that planning in order to control heat stresses by replacement of drinking is necessary.

Introduction: High mental workload is one of the important factors that results in errors in safety and occupational health scope, and its measurement has high importance. Therefore, this study aimed at determining the validity and reliability of Verbal Online Subjective Opinion (VOSO) and Modified Cooper-Harper (MCH) scales in measuring mental workload.Methods: This study was conducted on 90 male students of Iran University of Medical Sciences. In this study, forward-backward translation was used for translation of scales. Moreover, Content Validity Ratio (CVR) and Content Validity Index (CVI) were calculated considering the suggestions of 6 ergonomics and occupational health experts. The Hybrid Memory Search Task software was used to create mental workload. Convergent validity of scales was calculated using correlation of scales with reaction time and then test-retest method was used to determine the reliability of scales.Results: Content and convergent validity of scales were confirmed and correlation of both scales with reaction time were higher than 0.8. Moreover, for determination of scales reliabilities, Pearson correlation coefficient between scales values in test and retest trials were 0.86 and 0.91 for VOSO and MCH, respectively.Conclusions: It seems that in regards to confirmation of validity and reliability of VOSO and MCH in this study and their high correlation with reaction time, these scales could be used in measurement of mental workload.

Introduction: In Iran, there is a lack of reliable data on acoustic characteristics of building materials applied in offices and industrial rooms. This study aimed at investigating noise absorption characteristics for current building and acoustics materials and provided an acoustic database.Methods: In this cross sectional study, a minimum of 60 building and acoustic materials were tested in the acoustics laboratory located at the school of health. Measuring the absorption coefficient was performed using the Impedance Tube (SW60, BSWA) along with 1.4" Microphone (MPA416) and power amplifier (PA50) in a frequency range from 125 to 6300 Hz, according to ISO10534-2. The data was analyzed using Excel 2013 software.Results: The sound absorption coefficients for different types of materials were presented based on octave band. The results showed that an increase of sound absorptions with a rise in the thickness of the chemical foams. The highest absorptions were observed at medium and high frequencies. However, the impact of materials density on the increase of sound absorption was inconsiderable compared with materials thickness. Regarding sound absorption, the polyurethane foams have better performance than the polyethylene foams.Conclusions: Based on the obtained acoustics database, acoustics professionals could conduct more reliable evaluation about acoustic condition of residential, industrial, and office rooms in design and operation phases. The results confirmed that material thickness is one of the main features affecting sound absorption, especially for high efficiency absorbents like chemical foam.

Introduction: In many workplaces, there is exposure to heat and light simultaneously. This study investigated the combined effect of heat and lighting on some cognitive performances, i.e. reaction time.Methods: The present semi-experimental study was conducted in 2015 on 33 healthy students (16 girls and 17 boys) with a mean age of 22.1 in a thermal stress chamber. The reaction time parameter was measured by a reaction time measurement device, after exposure to different heat surfaces (dry temperatures of 22°C and 37°C) and lighting surfaces (200, 500 and 1500 lux). Data were analyzed using ANOVA test in SPSS 20.Results: The results showed that the average simple, diagnostic, two-color selective, two-sound selective reaction times and reaction time error increased after combined exposure to heat and lighting, which showed a significant difference (P<0.05). The maximum score of reaction time belonged to 37°C and 1500 lux, the minimum score of reaction time belonged to 22°C and 1500 lux.Conclusions: The results of this study showed that increasing the levels of heat and lighting by increasing the reaction time and reaction time error of people can decrease the cognitive performance. Therefore, workplaces must be optimized and attended in terms of heat and lighting.

Introduction: Maintenance of work ability and continuous effort to improve reduced work ability of employees is a major concern for managers. This study aimed to determine the level of work ability index and its relationship with life style in mechanics of thermal power plant.Methods: A total of 60 mechanics from selected thermal power plants were included in this cross-sectional study. Health promoting behaviors were tested by Walker lifestyle promoting questionnaire. Work ability was assessed by work ability index (WAI) and the final score was calculated from answers to its seven dimensions. Data was analyzed using SPSS 21 software.Results: The mean value of work ability index in this study was 34.80 ± 5.76. The WAI categories were 16.66% in "excellent", 36.6% in "good", 30% in "moderate", and 16.66% in "poor" levels. The association between life style factors and WAI was statistically significant (P<0.05). Lower WAI was associated with increased age, more work experience and lower education (P<0.05).Conclusions: The average of work ability index in mechanics was at the average level. In addition, there was a significant relationship between work ability indexes and life style.

Introduction: Based on estimations, each year about 250 million work-related injuries and many temporary or permanent disabilities occur, most of which are preventable. Oil and gas industries are among industries with high incidence of injuries around the world. The aim of this study was the investigation of the role and effect of different risk management variables on Lost Working Days (LWD) in the seismic projects.Methods: This study was a retrospective cross-sectional and systematic analysis, which was carried out on occupational accidents between 2008 and 2015 (an 8-year period) in different seismic projects for oilfield exploration at Dana Energy (Iranian Seismic Company). The preliminary sample size of the study was 487 accidents. A systems analysis approach was applied by using Root Case Analysis (RCA) and Structural Equation Modeling (SEM). Tools for the data analysis included the SPSS 23 and AMOS 23 software.Results: The mean Lost Working Days (LWD) was calculated as 49.57 and the final model of structural equation modeling showed latent variables of safety and health training factor (-0.33), risk assessment factor (-0.55) and risk control factor (-0.61) as direct causes that significantly affected LWD in seismic industries (P<0.05).Conclusions: The findings of the present study revealed that combination of variables affected LWD. Therefore, the role of these variables on accidents should be investigated and suitable programs should be considered for them.