مجله مهندسی بهداشت حرفه ای
سال سوم شماره 1 (بهار 1395)

To determine the effectiveness of hearing protective devices that lack the technical information are one of the major challenges of occupational health experts to judge the impact of this exposure on reducing the level of occupational exposure to noise. The aim of this study was to design a built a hearing test adapter and expriment it to determine the reduction rate of earmuffs and earplugs.
Technical information in real environments and glass industries were Hamadan kitchen garden and guards to ensure exceptional performance test results were compared with computational methods.
The results of the testing of Personal hearing protection compared with the results in real industry environment and octave-band method, have shown good regrassions average operating transmission losses. Results showed that the average noise reduction between measured and calculations method for earmuffs 9.3, 8.8 dB and 9.3, 11.2 dB for earplugs respectively. Comparison of the tests, did not show significant differences between the results in tow methods (P>0.05).
The results of the testing designed Adaptor for some hearing protectors showed that the valid tool for used to reduction rate teste of earmuffs and earplugs.

A systematic approach is needed for effective coping an incident. In such a system, the preparedness is the top priority. The organization’s readiness depends on some factors, including regular exercises. To conduct a proper exercise it is necessary to have a comprehensive scenario. Despite of repetitive execution of exercises, there is no commonly accepted template for it. The present study aims at selecting preferred method for developing an emergency exercise.
In the present study, ISO 22398 and HSEEP as the two common patterns were compared through quantifying their usability and chosen by AHP. A panel of crisis experts scored the usability criteria of methods and selected the preferred method.
The assessment of usability of both patterns revealed the preference of ISO pattern in comparison with the HSEEP pattern. The HSEEP method had the better score in learnability and satisfaction, but, the effectiveness, efficiency and total score were higher for ISO 22398.
To develop an emergency scenario, it is necessary to follow a suitable pattern. The pattern presented by ISO 22398 is more usable in comparison with HSEEP paten.

In this research the solid phase micro extraction (SPME) for sampling and determination of carbon tetrachloride and chloroform in air was developed and effect of ambient parameters on SPME was assessed.
For this purpose standard chamber was built in the laboratory. The concentrations of compounds in the chamber were measured with SPME. The optimum condition for extraction were determined and compared with 1003 method of national institute occupational safety and health (NIOSH-1003). The samples were analyzed with gas chromatography-mass spectrometry.
Carboxen-Poly dimethyl siloxane (CAR/PDMS) has high adsorption in comparing with other fibers and there were no significant differences between sampling rates at different temperatures (range of 20 to 30 °C) and air velocities (2 to 50 cm/s) but, relative humidity (RH) had a significant effect on sampling rates. The results showed that samples can be storage in refrigerator at 4 °C for 3 days. The correlation coefficient of results between SPME and NIOSH-1003 for carbon tetrachloride and chloroform were 0.99 and 0.98 respectively and relative standard deviation of reproducibility between fibers for carbon tetrachloride and chloroform were 13.6 and 12.8 respectively.
This study was showed that SPME was more sensitive than NIOSH-1003 method and successfully applied for determination of time weight average of carbon tetrachloride and chloroform as a passive method.

The workers employed in stone cutting workplace are exposed to hand-arm vibration and its complications. The aim of this study was to evaluate the exposure to hand-arm vibration and its health effects on workers in the stone cutting workshops.
In this descriptive-analytic study, 40 workers of Hamadan city stone cutting who worked with stone cutting machines were examined. Measuring exposure to hand-arm vibration was performed by standard methods ISO 5349. Symptoms related hand-arm vibration syndrome using a questionnaire construction was studied. Data were analyzed using SPSS software.
Results showed that 8-hour equivalent acceleration of hand-arm vibration exposure in stonecuttingworkers was exceeds the permissible exposure levels of country (Pv In regard to exposure level of stone cutting workers compared with the national exposure limit, the training of health care, non-smoking, and use of anti-vibration gloves, work rotations canthe effective in reducing the risk of health effects. Furthermore, it seems essential to track the health effects associated with human vibration by use of screening tests in the work place seem.

Musculoskeletal disorders are a major part of occupational diseases in working environments. The aim of this study was evaluates the risk factors of musculoskeletal disorders by the assessment of Muscle Fatigue Assessment method (MFA). It also sought to determine the effects of an ergonomic intervention on the mentioned risk in an Assembly industry.
This study conducted on 15 people working in the Assembly line. Medical records of Assembly line workers were reviewed and Nordic Musculoskeletal Questionnaires (NMQ) after one year of intervention was completed. Activities of these workers in Assembly line were evaluated by Muscle Fatigue Assessment method (MFA) and workers were given the necessary training. Data were analyzed in SPSS-16.
The initial evaluations showed that neck, back, leg and knee, respectively in 6.67, 20 and 13.33 percent were in the "very high" priority corrective measures. Re-assessments after the intervention showed that Percent of people with musculoskeletal disorders in the neck in the "very high" corrective actions changed to zero. The percent of organs at the level of "high" corrective actions before the intervention was greatly reduced. For example, around the waist from 60% to 33.33% and neck from 53% to 26.27% after intervention were reduced. A total of 30 cases of abnormalities detected before the intervention, after intervention, this number reduced to 11.
According to MFA Score, risk of musculoskeletal disorders was reduced by intervention in this industry and According to Questionnaire, prevalence of musculoskeletal disorders also significantly reduced.

Control of fugitative dust from mining process and application of an appropriate and economical system for dust collecting is essential. The goal of this study was cost-benefit analysis of an integrated systems and compare to bag filter in a crushing plant of a mining company.
A local exhaust ventilation system for capture of emitted particlees, a water spray for dust suppresion at sources and parallel Stairmand model cyclones as dust colletor were designed and installed based on the standards and guidelines. Then, efficiency of wetting and industrial ventilation system for control of ambient dust personal exposure and environmental emission have evaluated as integrated and alone. Finally, cost-benefit analysis of this system was compared to bag filter.
The efficiency of this system for control personal exposure repairable particles and emitted dust to ambient air was 87% and 95% for plant 1 and 88% and 95% for plant 2, respectively. The concentration of emitted emitted dust from stack to environment were 121.28 mg/m3 and 112/68 mg/m3 for plant 1 and 2, respectively. The capital, operational and maintence costs of this option was 217 and 0.992 billion rials lower than bag filter. Also, annuall collected dust by cyclones was worth 518 million rial.
According to results, integrated system had a significant impact on emitted dust in workplace and environment. The economical analysis domonstrated 73% and 80% savings in capital and operational costs compared to bag filter. Total costs of implented project will be compensated at 220 day with recovered dusts, therefore, in the same condition, it can be suggested as the favourable and economical solution.

using fossil fuels, some hazards such as explosion and fire are probable. This study was aimed to consequence modeling of fire on Methane storage tanks in a gas refinery using analyzing the risk, and modeling and evaluating the related consequences.
Hazard analysis by PHA was used to choosing the worst-case scenario. Then, causes of the scenario were determined by FTA. After that, consequence modeling by the PHAST software was applied for the consequence analysis.
Based on some criteria, the fire of methane gas tank (V-100) was selected as the worst-case scenario at the refinery. The qualitative fault tree showed three factors including mechanical, process, and human failures contribute in gas leakage. The leakage size and weather conditions were effective on the distance of radiation. Using consequence modeling, thermal radiation was considered as the major outcome of the incident. Finally, for outcome evaluating, probit equations were used to quantify losses and the percentage of fatalities due to the methane gas leakage and fire occurrence. The maximum number of fatalities caused by fire was obtained 23 persons.
In conclusion, the methane gas vessel in the refinery can be considered as the main center of hazard, therefore the implementation of the safety rules, eliminating mechanical failures, personal protection and education, and Effective measures to prevent and fighting of fire are proposed for decreasing the probable losses and fatalities.

One of the recommended methods for evaluation effectiveness of hearing protection is use the acoustic fixture accordance with standard ISO 4869-3. The aim of this study was evaluate the acoustic performance of fixture for using in noise reduction rate tests of hearing protection devices in the laboratory.
In this cross-sectional study , noise reduction rates of five common ear muffs used in the Iran industries were investigated based on the ISO 11904 standard, microphone in real ear method, using noise dosimeter (SVANTEK , Model SV102) equipped with microphone SV25 model which can install inside the ear on 30 subjects under laboratory conditions. Also, noise reduction rate of earmuffs was determined using the fixture model AVASINA9402 accordance with standard procedures. Data were analyzed using the software SPSS21.
The results showed the real noise reduction rates of the earmuffs on the studied subjects are from 59% to 94% nominal reduction rates. That rates for the ear muffs on the studied fixture are from 64% to 92.The results showed that the noise reduction rates of the ear muffs on subjects compared with and noise reduction rates of the ear muffs on fixture were not statistically significant (p> 0.05).
The results showed the accuracy of noise reduction rate of earmuffs using the fixture compared with real subjects is acceptable. Hence, the fixture is good choice for environments where there’s no possibility of acoustic evaluation on real subjects, also for quality control of productions in the earmuff manufacturers.