دو ماهنامه سلامت کار ایران
سال چهاردهم شماره 4 (مهر و آبان 1396)

Natural gas pipeline network is an important part of a city’s infrastructure for energy transmission. As the gas pipeline network becoming vaster and more complex, accident caused by the leak of gas pipeline network occur. Accidents consequences caused by gas pipeline rupture, can directly threatening the safety of persons and properties in the city. Thus, it is necessary to do risk assessment for natural gas pipeline network. In this work, risk assessment of natural gas pipeline network for Baharan town in Sanandaj city has been investigated.
In this study, there was a limitation because of unavailable and managed required data for the risk management process. Thus, for the risk assessment, Analytic Hierarchy Process (AHP) technique was used in municipal gas distribution network. After investigating the reported data of any accidents and leakages, the main effective parameters have been recognized and the related quantitative weights were determined.
The statistical analysis showed a spill event municipal gas distribution network for a period of three and a half years (from the beginning of 1390 to the end of the summer of the 1393), as a factor based on the selected studied area (Baharan town, Sanandaj city). Between the investigated factors and based on the AHP technique, involvement index of individuals and substance hazard (0.165, 0.15, respectively) showed the maximal amounts of the most important parameters with major effects on the risk assessment and pressure index (0.0031) showed the minimal amount with the minor effect on the investigation.
To assess the risk factors of municipal gas pipeline network, there is not a well-covered investigation for complete requirement in the Iran. Therefore, because of the useful data obtained by the used technique here, AHP technique, it is recommended to gas safety managers to use these methods and the most important factors identified in this study for promoting safety and reduce accidents in municipal gas distribution network in gas distribution lines.

Regarding high emission rates of volatile organic compounds in the atmosphere by different industrial and transportation sources and their adverse effects on human health and the environment, the need to remove these chemicals from gas streams using new technologies with low energy consumption and high efficiency has been more evident. In this study, the catalytic effect of AC-ZnO was investigated on the removal of these compounds (toluene) and their product distribution in a hybrid catalytic plasma system.
AC-ZnO catalyst was prepared using sol-gel method. Non-thermal plasma was generated utilizing a high voltage power supply and a dielectric barrier discharge reactor. Plasma and catalyst techniques were then combined in a two-stage configuration. Reactor influent and effluent air sample analysis was carried out using GC-MS and on-line gas monitoring devices.
The results showed that there was a high synergistic effect between plasma and catalyst so that the total removal of toluene was obtained at specific input energy of 1000 J L-1, while the removal percent was around 88% at the same energy delivery with plasma-alone system. The selectivity towards CO2 was also increased over catalyst bed and some of the by-products such as NO, and NO2 were totally removed and the effluent amount of O3 was negligible.
It can be concluded that the plasma-catalyst hybrid technique is a new and promising method for the removal of volatile organic compounds causing the increase of removal efficiency, and the hazardous products and energy consumption reduction.

The clean room is under the control of concentrations of airborne particles play an important role in the production of drugs and high-tech products. Clean air flow pattern in the room is one of the important parameters of particle concentration and distribution of air pollution and need to be accurately modeled. So in this study was to evaluate and simulate the flow pattern of clean air in the room was investigated.
This study used an experimental study that was conducted at 2015 in the pharmaceutical industry .The methodology used in this study was to determine the air flow pattern in cleanroom. In this study, 3 clean room with 3 cleanliness classes B, C and D were studied. Then simulate the flow pattern, determine the velocity vectors in the cleanroom is cleared by CFD techniques.
The findings of this study showed that air flow rate measured in experimental models with air flow rates predicted by FLUENT software under the same conditions and at the same spacing is very close to each other .Also airflow velocity contours for 3 the cleanliness class were determined .In addition, the results of measurement of particle concentration in clean rooms shows the mean concentration of particulate contamination in three classes cleanliness was below the standard limit.
This study showed that RNG K-ℇ turbulence model the most appropriate model to simulate air flow pattern in the room is clean. There is also equipment and a tool in a clean room on the pattern of air flow and ultimately affects the particle removal efficiency in the clean room.

Road transportation of chemicals due to occurring various accidents and their hazardous consequences has high importance. The aim of this study was to determine safe distance in the accidents of road transportation of toxic chemicals in order to use in emergency response planning.
In this study, firstly, transportable chemicals -by road- were studied and ammonia, chlorine, 1,3-butadiene, benzene and toluene were selected for further study and modeling of toxic materials releases. Next, chemical exposure index (CEI) was determined and hazard ranking was done. Finally, modeling of toxic substances releases was done using ALOHA and PHAST softwares.
The results showed that, using the CEI index, ammonia, chlorine and 1,3-butadiene with exposure indexes of 597, 548 and 284, respectively, have high importance and need further investigation. In the final assessment that was done according to ERPG-3 concentration, using ALOHA software, ammonia with 2800 meters, and using PHAST software, chlorine with 3004 meters, have the highest hazard distances.
Assessment of the results showed that the used softwares and the CEI index dont have the capability to provide correct results at low concentrations (ERPG-1 & 2). Due to difference of the results using PHAST and ALOHA softwares, and CEI index, it is recommended to use the highest hazard distance-obtained by ERPG-3-for emergency response planning, without paying attention to type of the material and type of the softwares.

The chlorobenzene is an intermediate chemical that is used in the production of commodities such as herbicides, dyestuffs, and rubber and Causes neurological complications and effects on the respiratory tract. In this research solid phase micro extraction (SPME) was used for the sampling of chlorobenzene in air. The optimum conditions for analysis with gas chromatography-Mass spectrometry (GC-MS) were determined
The sampling of chlorobenzene was done in a dynamic atmosphere generation system with SPME. The kind of fiber was selected and the optimum temperature and desorption time in injection port of GC were determined and results of measurement were compared with the NIOSH-1003 method. Samples were analyzed by gas chromatography-Mass spectrometry.
Carboxen-Polydimethylsiloxane (CAR/PDMS) in retracted mode has high absorption compared to other fibers and was selected for sampling. Desorption temperature in the injector of GC were also optimized in three levels from 200 to 280 and results showed no significant difference were observed for extraction of analyte from SPME (P>0.05).The equilibrium time at exposed condition in SPME was 30 minute but equilibrium time is extended for several hours in retracted mode. There were no significant differences between sampling rates at different temperatures and air velocities (P>0.05) but, the increase of relative humidity (RH) had a negative effect on sampling rates (P It is concluded that SPME in retracted mode is an alternative method for determination of chlorobenzene in air and could be applied as a passive method for the determination of the time weight average (TWA) of chlorobenzene in workplaces.

The diabetes mellitus is one of the important and most complicated diseases. The non occupational risk factors are known but occupational risks are unknown. Objective of this study was determination the risk of shift work on diabetes mellitus.
In a historical cohort study from 460 shift workers and 410 non shift workers in industry this study was done. With a checklist the risk factors were gathered and the data were analyzed in SPSS 16, with t-test,chi-2 , exact, relative risks(P Fasting blood sugar in shift workers was 89.31±12.16 and in non shift workers was 87.76±14.36 and oral glucose tolerance test in shift workers was 125.66±6.36 and in non shift workers was 124.18±1.11(P=0.92 , P=0.95).
This shift work had not effects on fasting blood sugar and starting the diabetes.

Feel job satisfaction is the most basic components of mental health and an important factor in career success. The aim of this study was identify of effective factors on job dissatisfaction of primary school teachers of Bojnord city.
In this descriptive – correlation study, the population were all primary school teachers that who were working in 2015 (N= 653). 200 teachers were selected by the use of multistage cluster sampling method. Participants in this study were measured by "measuring factors influencing job dissatisfaction questionnaire". In order to analyze the data, the exploratory factor analysis with principal components by use software SPSS-22 and the confirmatory factor analysis by use software AMOS-22 were applied.
Principal components analysis using varimax rotation yielded a three-factor solution of improper management (27 items), individual factors (12 items) and lack of welfare agents (9 items) that jointly accounted for 41.07 percent of the total variance. The next step to explain the concept, confirmatory factor analysis was performed. The results showed job dissatisfaction questionnaire building from three construct latent. Indices of confirmatory factor analysis model showed that the model has an acceptable fit.
The results of this study showed the importance of improper management, individual factors and lack of welfare agents as the factors that influence on job dissatisfaction of primary school teachers in Bojnord city. Therefore, custodians of educational system in order to the micro and macro planning, should rely on these variables.

One of the innovative technologies for air pollution control is non-thermal plasma. The dielectric barrier discharge reactor is one of the reactors that applied in non thermal plasma technology for air polluation control. In dielectric barrier discharge reactor, the distance between the electrodes for electric discharge is low and led to increasing space velocity of the pollutant in the discharge zone. This increase in the velocity results in a decrease in the probability of collision of the produced active species with pollutant molecules, which consequently decreases the efficiency of pollutant degradation. The aim of this study was to design a new dielectric barrier discharge reactor for increase the dischrge gap zone.
The non-thermal plasma reactor employed in this study was made of quartz as a rectangular cube shape. In this reactor, the expanded graphite was used as the discharge electrode which was poured uniformly in the bottom of the reactor and a copper plate was on the outer surface of the reactor applied to play the role of the earth electrode. Chloroform removal efficiency as a function of flow rate, concentration of pollutants and applied voltage was investigated in this reactor. In addition, it was observed that the exhaust gas from the reactor contains nitrogen oxides, chlorine, hydrochloric acid, phosgene, trichlorobenzaldehyde and trichloroacetaldehyde.
Results of the study showed that electrical discharge was created in larger discharge gap which resulted in space velocity decrease of pollutants in this region and caused to increase of chloroform degradation. Moreover, flow rate increase affected lightly on the degradation which is owing to the adsorption property of the expanded graphite as well as an increase in discharge gap region.

Due to low concentration of melatonin and also the existence of other compounds in body fluids, measuring the amount of melatonin is a serious challenge for the analysts. Before measurement of melatonin amounts using chromatographic method, sample preparation is unavoidable. The aim of current study is develop a new sample preparation method that not only have high accuracy and validity, but also can using by conventional equipment available in the laboratory to determine trace levels of salivary melatonin. For this purpose, the dispersive liquid-liquid microextraction (DLLME) method, that has not been used so far to preparation of salivary melatonin samples, were optimized.
Optimization procedure involved evaluation of eight factors affecting DLLME method. From these factors, seven were examined in four levels, and just pH was done in five levels. Accuracy and precision of the optimized method was evaluated at three concentrations of 50, 100, 250 pg.ml-1 by achieving CV% for day-to-day and within-day reproducibility.
Optimum values were determined. Accuracy and precision of the optimized method was investigated at three concentrations of 50, 100, and 250 pg.ml-1 by achieving CV% of 6.29, 2.39, and 1.82 for the "day-to-day" and 4.49, 2.68, and 1.83 for "within-day" reproducibility.
Due to the results of this study for Coefficient of variations, the optimized method was provided with proper accuracy and precision. Although optimized extraction factors must be fit analyte, but these factors can be used for similar chemical compounds with a slight modification.

Access to an Anthropometric database is essential for human-centered design. Several Iranian researchers preceded their studies with the aim of collecting useful data for designing workstations. The present study aims to review all of these related studies in order to introduce the state of the art and help to clarify future studies.
Databanks of Google scholar, SID, Iranmedex, Magiran, MedLib and Civilica were looked for finding related literature by means of appropriate keywords. 699 papers were found in national databanks; while 900 were found in the Google scholar. Inclusion criteria were set as having the aim of collecting Iranian adults’ anthropometric data for workstation or tool design.
4/99 percent of all studies were entered to the study (i.e. 25 papers). Literature dated from 1977 to 2014. Their methodologies and findings were compared.
Results showed that existed studies are applicable according to their methodologies; meaning that applying their results into general Iranian population would have some limitations. Therefore, it is necessary to do up-to date the existed anthropometric tables; as well as to produce a comprehensive table for Iranian anthropometric dimensions.

Nominal noise reduction rating of the earmuff manufacturers can be different compared with the actual noise attenuation rating. The current study aimed to determine the actual noise reduction rate of current hearing protection devices in the real workplaces using a field microphone in real ear method (FMIRE).
In this cross-sectional study, five common earmuffs were studied in both industrial environments with different noise nature on the 50 workers who were selected randomly. Noise reduction ratings of ear muffs were measured based on the ISO 11904 standard, microphone in real ear method, using noise dosimeter (SVANTEK, model SV 102) equipped with a microphone SV 25 model which can install inside the ear. In addition, the knowledge, attitudes and performance of employees about hearing protection were assessed by the developed questionnaire. Data was analyzed by SPSS 21.
Independent of the type of noise exposure, actual insertion loss values for ear muffs in one octave-band frequency was less than the nominal insertion loss values. Actual noise reduction rates of the earmuffs in the exposed of dominant noise low frequency are less than the nominal reduction rates (p The frequency nature of noise is very impressive on the actual noise reduction rates can be achieved from earmuffs. Therefore, data about the frequency analysis of ambient noise is key ingredient when selecting hearing protectors in any workplaces. FMIRE could facilitate rapid and simple measurement of the actual acoustic performance of earmuffs in real conditions of industrial environments.

Various factors affect the safety performance of employees and safety locus of control (SLOC) is one of the main determinants. People with an internal locus of control believe that they can control events and conditions and People with an external locus of control believe that events caused by factors such as chance, fate, environment and performance of other people. Therefore, to prevent accidents attention to the SLOC is very important. This study aimed to determine the SLOC and its related factors in employees of an industry.
This cross sectional study was conducted on 172 employees of an industry in a central provinces of Iran. Data collection was performed using demographic-job and SLOC questionnaires. Data Gathering was performed in a semi-supervised manner. Data analyzed with SPSS software (version20) using independent T tests, Pearson correlation and liner regression.
The mean score of SLOC was 38.5±5.08 and was Larger than the mean intended to scale (µ=36) and was internal in the studied population. Chronic disease, smoking and Employment in second job have significant relationship with SLOC but other studied variables were not significantly associated with SLOC.
Some variables may be influence the perception of people about level of control that they can have on events and in fact affect people's safety locus of control. As a result, these variables could change safety locus of control and indirectly affect safety performance and accident occurrence.

Car seats have a significant impact on driver comfort and reduction of postural load on the low back of the driver. The purpose of this study was to compare three common types of car seat in Iran on the driver's fatigue and muscle discomfort.
Ten participants completed 2 hours of simulated driving for each of the three type of car seat in different days within a week. During driving task, the electrical activity of the lumbar erector spinae muscles were recorded every 15 minutes and discomfort rate measured every 30 minutes by a visual indicator. The RMS, mean frequency (MNF) and median frequency (MDF) were calculated and used to assess muscle load and fatigue. Repeated measure ANOVA was performed to assess the effect of car Seat on muscular activity and fatigue.
A significant difference found between various types of car seat with regards to subjective measure of discomfort data (p Although the level of activity and fatigue of erector spinae muscles showed no significant difference during two hours of driving, but self reported discomfort in low back muscles suggested a significant difference. Based on the findings of this study, it seems some type of car seats may cause discomfort however there was no significant difference between three types of car seat with regard to fatigue. In order to design of ergonomic car seat further studies recommended.

The current conventional effective elements on transporting or reducing of airborne aerosols and building indoor air quality are natural ventilation systems. Natural ventilation is supplying fresh air and cooling down by replacing ambient air which is one of the effective parameter on social hygiene and health aspect through controlling airborne pathogens and their related nosocomial infections in different part of life particularly in hospitals; and is known as one of the cost-effective solutions in this field. The aim of this study is investigation of natural ventilation potential in the different ward of Tehran University of Medical Sciences affiliated hospitals.
In this cross-sectional study, humidity, temperature, wind speed and room characteristics of 35 wards of 12 hospitals affiliated to Tehran University of Medical Sciences which consisted a total of 269 rooms were investigated, and results were compared with related standards and guidelines. Investigated wards included infectious, blood, gastrointestinal and tuberculosis wards which have importance from airborne pathogens perspective. The correlation between ACH index and altitude, temperature and humidity along with wards classification to airborne and non-airborne sections, and evaluation of their ACH mean were conducted with Kruskal–Wallis and Fligner-Killeen test by R (version 3.2.0) and Excel 2013 software.
The minimum, maximum and average values of wind speed, humidity and temperature in airborn and non-airborn sections were measured as (0 and 2.9 m/s), (13.5% and 40%) and (24 and 30.7 ºC), respectively. Also, the means of ACH in airborne and non-airborne were 20.5 and 31, respectively. In addition, significant relations among the different parameters of study according to the Kruskal–Wallis test were observed (P-value According to the obtained results of present study and comparing the results with related standards (ACH=12) indicated that opening of the doors and windows of rooms have high potential in reducing the nosocomial infection in studied hospitals. Furthermore, more energy costs can be saved by using natural ventilation in different wards.

The emission of sulfur dioxide in air has hazardous effects on human health and environment. In this research the use of surfactants with sodium bicarbonate and limestone for the removal of sulfur dioxide was studied.
A packed scrubber was used and the effect of absorbents (limestone or sodium bicarbonate), the kind and concentration of surfactants were assessed. Concentration of sulfur dioxide was measured at inlet and outlet of scrubber by real-time devices.
The results showed that removal efficiency of sulfur dioxide was enhanced when the concentration of cation surfactants with limestone or sodium bicarbonate increased but when the concentration of anion surfactants with absorbents increased it caused the decrease of removal efficiency of sulfur dioxide. The highest average of removal efficiency (94.54%) was reported when 2% of limestone with 0.01 mole of cation surfactant was used and concentration of sulfur dioxide was 55 ppm. The efficiency was also high whenever sodium bicarbonate was used instead of limestone.
The results of this research show that using bicarbonate sodium or limestone with cation surfactants is more efficient than using these absorbents alone for removing sulfur dioxide from air pollutants and this removal process can be applied for controlling sulfur dioxide at industrial process.