مجله مهندسی بهداشت حرفه ای
سال سوم شماره 3 (پاییز 1395)

In some jobs, physical activity can be done in high noise pollution that 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 the hot and humid conditions.
This experimental study was performed on 14 healthy men 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 trial and noise exposure trials in levels of 65, 75, 85 and 95(dBA).
In hot and humid weather conditions. In the sitting, low workload, moderate workload and heavy workload situations heart rate average was significantly between non- exposure to noise and noise exposure at level of 65, 75, 85 and 95 dB (A) (P

Quality and efficiency of health, safety, and environment (HSE) management systems play a vital role in achieving their goals. Considering 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 very important. The present study was conducted to construct a proper framework for assessing MAPNA group contractors in terms of their health, safety, and environment performance.
In the first step of the study, all documents and literature associated with performance assessment were reviewed. In the second step, using a focus group approach, a basic model for assessing HSE management system was designed. Lastly, the framework was tested and credited on three major contractors of MAPNA group.
The proposed framework was composed of five criteria. The main criteria 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.
The proposed framework make 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.

during the physical activity in hot environments, sweating with evaporation, the important physiological response of the body increases which can be 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.
This cross sectional study was done on 90 workers of workers in sugar factory which were exposed to heat. Heart rate and oral temperature were respectively measured using a heart rate meter and an oral thermometer. WBGT index was recorded and the HSSI questionnaire was completed simultaneously, in order to assess dehydration level was measured of refractometer. Data obtained from this study were analyzed using compare means and t-test, paired t-test tests by SPSS 20 software
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 our population had some degree of dehydration.63.4% of them were significantly dehydrated (urine SG>1.020) and 28% of them 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, heart rate were significant(p A high percentage of the study population had some degree of dehydration that based on the results is worrying. It seems that planning in order to control of heat stresses by replace drinking is necessary.

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. So, this study aimed to determine validity and reliability of Verbal Online Subjective Opinion (VOSO) and Modified Cooper-Harper (MCH) scales in measuring mental workload.
This study was conducted on 90 male students of Iran University of Medical Sciences. In this study, the Forward-Backward translation was used for translation of scales. Moreover, Content Validity Ratio (CVR) and Content Validity Index (CVI) were calculated by having suggestion 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.
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.
It seems that in regard to confirmation of validity and reliability of VOSO and MCH in this study and their high correlation with reaction time, it can use these scales in measurement of mental workload.

In Iran country, there is a lack of reliable data on acoustic characteristics of building materials applied in the offices and industrial rooms. This study aimed to investigate noise absorption characteristics for current building and acoustics materials and provided the acoustic database.
In this cross sectional study, the minimum of 60 building and acoustic materials were tested in the acoustics laboratory located in 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 frequency range from 125 to 6300 Hz according to ISO10534-2. The data was analyzed using Excel 2013 software.
The results of the sound absorption coefficients for different types of materials were presented based on octave band. The results showed that the increase of sound absorptions by rising the thickness of the chemical foams. The highest absorptions were observed in the medium and high frequencies. However, the impact of materials density on the increase of sound absorption is inconsiderable compared with materials thickness. In view point of sound absorption, the polyurethane foams have better performance than the polyethylene foams.
Based on the obtained acoustics database, acoustics professionals can conducted more reliable evaluation about acoustic condition of residential, industrial and office rooms in the 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.

In many workplaces there is exposure to heat and light simultaneously. This study investigated the combined effect of heat and lighting on some cognitive performance, i.e. reaction time.
the present semi-experimental study was conducted 2015 on 33 healthy students (16 girls and 17 boys) with a mean age of 22.1 in the thermal stress chamber. The reaction time parameter by the reaction time measurement device, after exposure to different heat surfaces (dry temperatures 22 °C and 37 °C) and lighting surfaces (200, 500 and 1500 lux). Data were analyzed using ANOVA test in SPSS-20.
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 and showed a significant difference (P

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 relation with life style in mechanics of thermal power plant.
A total of 60 mechanics from selected thermal power plant were included in this cross sectional study. Health promoting behaviors was tested by Promoting lifestyle questionnaire walker. Work ability was assessed by the Work Ability Index (WAI) and the final score was calculated from answers to its seven dimensions. Data was analyzed using SPSS 21 software.
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. Association between life style factors and WAI was statistically significant (P Average of work ability index in mechanics was at average level. Also there is a significant relationship between work ability indexes with life style.

Based on estimations, each year about 250 million work-related injuries and many temporary or permanent disabilities occur which most are preventable. Oil and Gas industries are among industries with high incidence of injuries in the world. The aim of this study has investigated the role and effect of different risk management variables on lost working days (LWD) in the seismic projects.
This study was a retrospective, cross-sectional and systematic analysis, which was carried out on occupational accidents between 2008-2015(an 8 years period) in different seismic projects for oilfield exploration at Dana Energy (Iranian Seismic Company). The preliminary sample size of the study were 487accidents. A systems analysis approach were applied by using root case analysis (RCA) and structural equation modeling (SEM). Tools for the data analysis were included, SPSS23 and AMOS23 software.
The mean of lost working days (LWD), was calculated 49.57, the final model of structural equation modeling showed that latent variables of, safety and health training factor(-0.33), risk assessment factor(-0.55) and risk control factor (-0.61) as direct causes significantly affected of lost working days (LWD) in the seismic industries (p The finding of present study revealed that combination of variables affected in lost working days (LWD). Therefore,the role of these variables in accidents should be investigated and suitable programs should be considered for them.