Journal of Health and Safety at Work

Evaluation of the influence of the clips geometry on the mechanical stresses generated on the thumb during assembly work

Hamed Salmanzadeh

Introduction: Nowadays, Snap-fits have many applications in the automotive industry, especially in assembly lines. They are used instead of the mechanical joints such as bolts, the cabling joints, and the car interior lining joints. Due to the special form of these fasteners, they are usually assembled manually. So, the form of clips’ contact area and the sharpness of the Snap-fits may cause the skin pains on the worker’s fingertips. This fact can cause an ergonomic study of these joints for reducing stress on workers and increasing their efficiency and health.

Material and Method: The Finite Element Method (FEM), which is one of the most recognized methods in numeric calculation and computer simulations, is used in order to study the pressures applied to skin due to the pain receptors in the middle layer of skin, and mechanical tensions created in the workers’ thumbs during their work with clips. In order to do this, first a 3D model of a thumb, based on the CT scan data taken from a real thumb sample was created. To identify the different layers of skin, Boolean operations were used. Afterwards, the limit conditions were determined and finally different structures were made to analyze the size, geometric shape and mechanical properties of the clips.

Result: In general, the results show that for those clips that their thumb touching surface is only round in edges, the most pressure on the middle layer of skin decreases as the radius of the round edge increases. Whereas such tensions, lightly increase as the radius increases in those clips that have a hybrid design (the combination of flat and curved surfaces). The result of the material analysis for clips shows that using elastic materials has only a limited effect on reducing tensions (only if rubber like materials are used) and for all tough materials, be it plastic or steel, the intensity of pressure tension would increase in the same manner on all the mentioned items.

Conclusion: The results suggest that during assembly work there are different factors which affect the tension on the fingers, factors like geometric structure, material and mechanical properties. However, the magnitude of those items’ effects are not the same, and that data can be observed while making an ergonomic design for clips.

Evaluation of cleanroom functional parameters (A case study in a pharmaceutical industry)

Zabiolah Damiri

Introduction: Nowadays, many modern industries require an environment with no contamination by particles and bacteria. An enclosed clean room environment is a place where parameters such as airborne particles, temperature, humidity, air pressure and air flow pattern is controlled. The aim of this study was to evaluate functional parameters of a clean room in a selected pharmaceutical industry.

Material and Method: This study was an experimental study conducted in 2015 in a pharmaceutical industry. The air flow rate and flow rate with airflow capture hood was used and multi sensor devices for measuring temperature, humidity and pressure of multi-sensor device. HEPA filter leakage test and counting concentration of particles in the cleanroom was done according to the ISO 14644 – 3(2005) standards using aerosol photometer and aerosol generator. In this study, 6 clean room relating to the 3 cleanliness classes B, C and D (in accordance with standard EU GMP) were evaluated. Meanwhile, both the 2 and 3-dimensional flow model using Computational Fluid Dynamics Software was simulated in this study.

Result: Measuring the parameters flow rate and air velocity, temperature (average temperature 20 ° C), relative humidity (below 50%), pressure (pressure less than 15 psi) for every three classes of cleanliness are all acceptable and less than the proposed standard. Furthermore, the results of modelling showed that the pattern of air flow in the room is correct paths in circulation. In the case of leakage test filters, the filter 29 filters tested 5 was leaking and ultimately determine the HEPA filters remove particles that average efficiency is 99.99%.

Conclusion: This study showed that the high volume and good quality of air entering the clean room affect the optimal efficiency and air flow rate, pressure drop and air penetration of the HEPA filters Also, the results of study show that the concentration of airborne particles in clean room is depend on the air flow rate and speed and adopting a good air flow pattern will affect the particle concentration.

Evaluating the efficiency of UVC radiation on HEPA filters to remove airborne microorganisms

Farideh Golbabaei

Introduction: Nowadays, HEPA filters is used in hospitals, clean rooms, microbiology hoods, ventilation of surgery rooms, and Pharmacy for removing microorganisms and reduce health hazard. The aim of this study is to increase the efficiency of HEPA filters with UVC radiation to reduce the density of airborne microorganisms.

Material and Method: The closed–loop chamber was made to evaluate Staphylococcus epidermidis, Bacillus subtilis bacteria and Aspergillus Niger, Penicillium fungi. The concentration of fungi and bacteria suspension Respectively was 106, 107 CFU/ml. After the suspension was prepared, it was sprayed into the closed loop chamber by nebulizer. Sampling was done with UVC radiation (1.8 mW/cm2 Illuminance) and no radiation (dark) that included time periods 60, 90 and 120 minutes. Microorganisms density was determined in term of CFU/m3.

Result: The result showed that there was a significant difference between UVC radiation and dark section for all the microorganisms (epidermidis, subtilis, Niger and Penicillium) at each time periods (P value< 0.05). This indicates that concentration of four microorganisms were decreased at all the time periods. UVC radiation could change the essential molecular substances for cellular factor. UVC can penetrate the cell walls of microorganisms. thus nucleic acids and other cellular vital material affected and will cause the destruction or inactivation of microorganisms.

Conclusion: UVC radiation is effectiveness to decrease concentration of four microorganisms. because UVC radiation could remove both bacteria and fungi. While the other studies in other countries, UVA radiation is only effective in reducing bacteria. Therefore, achieved greater efficiencies of HEPA filters, using HEPA filters with UVC will have a significant effect on reducing the density of microorganisms.

Risk assessment of chemical pollutants in an automobile manufacturing

Seyed Jamaleddin Shahtaheri

Introduction: In recent years, many national and international expert groups have considered specific improvements in risk assessment of chemical pollutants. This study considered to assess the risk of workers exposure to air pollutants in an automobile manufacturing in order to evaluate the health risk assessment due to the inhalation exposure.

Material and Method: To perform this study, a cross-sectional research was done in 2016. Methods number 1501 and 7602 of the National Institute of occupational safety and Health (NIOSH) were used for sampling and analysis of compounds BTEX and silica in the air. A total of 40 samples of compound BTEX were taken and analyzed by Gas Chromatography-Flame Ionization Detector (GC-FID). A total of 6 samples of silica were collected during the campaign. Silica analyses were performed by using visible spectrophotometry. Risk ranking was calculated using the hazard and exposure rate. Finally, the relative risk of blood cancer caused by exposure to benzene was estimated.

Result: The result demonstrated that, workers were exposed to 5 chemicals including silica, benzene, toluene, ethyl-benzene, and xylene during their work in manufactory. Among the pollutants in the breathing zone of workers, Silica and benzene were hazardous chemicals at high risk level. Following the estimation of relative risk of blood cancer caused by exposure to benzene, workers cumulative exposure to benzene was obtained to be 23.1 ppm per year and the capture relative risk was 1.1. The consequence demonstrated that, significant relationships were seen between workers exposure to benzene and both age and work experience, so that degree of exposure decreased steadily with increasing age and experience (P<0.001).

Conclusion: This research demonstrated that, benzene and silica in the automobile manufacturing were the highest risk. Also, painting hall workers, at automobile manufacturing, were directly exposed to the blood cancer risk of benzene.

Ranking occupations in high-rise construction workshops from the view point of safety culture using FTOPSIS-FAHP model

Mehran Amiri

Introduction: Safety in construction needs not only operating the executive laws and instructions but also the safety culture of all the workers in workshops. Safety culture is a factor by which all the workers are committed to having a positive share in the safety of their coworkers and themselves. Therefore, the aim of this study is identification of safety culture factors and ranking occupations in jobsites in order to improve the safety condition and promote the safety culture of high-rise projects.

Material and Method: In this descriptive-analytical study, first, safety culture criteria in construction projects are identified by a literature review. Then, 8 factors of safety culture are weighted using fuzzy analytic hierarchy process. Finally, 10 different occupations in high-rise workshops are ranked from the point of view of safety culture using fuzzy TOPSIS method.

Result: Results of ranking the criteria show that the most important criteria are safety attitude, supervision, policy of organization and safety training. Moreover, in high-rise construction the site superintendent and supervisor occupations have the highest and laborers have the lowest safety culture.

Conclusion: In this study, after evaluating different construction occupations by hybrid FTOPSIS-FAHP method, the results are compared with the results of previous researches. Here, it was found that the findings are consistent with previous studies. On the other hand, low level of safety culture of construction laborers among the investigated occupations shows weakness in safety training and attitude; hence, the factors such as more safety supervision and training must be considered in order to create a positive safety culture for the workers.

Validity and reliability of WRQoL-2 questionnaire for assessment of nurses’ quality of work life

Zeinab Kazemi

Introduction: Quality of Work Life (QWL) is a new form of job satisfaction which involves ones feelings about all aspects of their job. The aim of this study was to assess the psychometric properties of the Persian version of WRQoL-2 questionnaire for use in the nursing community.

Material and Method: In this study, backward translation method was used in order to verify the linguistics stability. Then, the cross-sectional study was conducted among 270 nurses working in a hospital, affiliated to Tehran University of Medical Sciences. Reliability and construct validity was investigated using test-retest and factor analysis, respectively. In addition, discriminant validity was assessed by comparing QWL mean scores of nurses satisfied with their salary and those who were dissatisfied.

Result: Regarding the reliability, it was observed that the repeatability coefficient were at an acceptable level for all dimensions of the WRQoL-2questionnaire. According to factor analysis, six components were identified with some questions in different groups compared to the original questionnaire. Considering discriminant validity, all components, except Stress at Work, obtained P-value less than 0.05.

Conclusion: Based on the acceptable level of reliability and validity of the WRQoL-2 questionnaire, use the questionnaire to assess the quality of work life of nurses is recommended.

Validation study of the questionnaire assessing level of knowledge in the rescue personnel regarding warning signs installed on the heavy machines road transporting dangerous materials

Sakineh Varmazyar

Introduction: Given the increase of road transportation of dangerous materials, if an accident occurs, the first groups that present at the scene are rescue groups (emergency، red crescent and firefighters). The aim of this study was to investigate the validity and reliability of the questionnaire assessing level of knowledge in the rescue personnel regarding warning signs mounted on the road heavy machinery.

Material and Method: Firstly, a multiple-choice questionnaire was designed using the literature and material safety data sheets (MSDS). Validity of the questionnaire was examined using the viewpoints of 10 experts. The reliability of the questionnaire was assessed using test-retest in 20 subjects of the rescue groups in two-week intervals. The cut point of the questionnaire was determined by the Receiver Operating Characteristic (ROC).

Result: The mean of age and work experience of the participants was 32.42 ± 2.57 and 7.75 ± 2.70. The results of correlation between the questions of the test showed that Cronbach’s alpha is 0.708. Also, the stability and reliability of test scores over time showed that the correlation between the questions in the first and second series was significance at acceptable level (r=0.698 with P-value=0.012(. The best value of cut point in the questionnaire of knowledge in the rescue personnel as obtained 18.5, with the sensitivity of 60% and specificity of 50%.

Conclusion: The validity and reliability of the knowledge assessment questionnaire in the rescue personnel were confirmed regarding the warning signs mounted on the road heavy machines; therefore, it can be used in the future studies.

Personal risk factors during heat stress exposure in workplace

Mehdi Asghari

Introduction: Heat stress is caused by many factors such as individual factors, environmental factors, and management factors. Individual risk factors can decrease the heat tolerance, and play an important role in heat stress disorders incidence. The aim of this study was to review individual parameters influencing the thermal stress and review the preceding studies.

Material and Method: In this review study sites such as Web of Science, Scopus, Pubmed, Iran Medex, Magiran, Google Scholar and SID databases were used for search. The keywords included heat stress, personal factors and heat exposure. The period of 1995 to 2015 was investigated, and finally 75 original articles were identified.

Result: At the individual level, exposure with a single risk factor may reduce the workers’ heat tolerance; while exposure with a combination of several risk factors probably synergistically increases the risk of heat-related disorders. Individual risk factors include age, gender, obesity, fatigue, race, and previous heat disorders and dehydration. In addition, some diseases (such as cardiovascular disease, diabetes and infectious diseases) or use of certain drugs or alcohol can reduce the heat tolerance.

Conclusion: It is necessary to pay attention to the mentioned items when selecting workers in the hot environments. Also, due to the lack of awareness and knowledge of workers, it is necessary to provide appropriate training programs to reduce the effects of heat stress.