JOURNAL OF OCCUPATIONAL HYGIENE ENGINEERING
Year:2017 | Volume:4 | Issue:2 |Papers Count:8

Background and Objective: Given that satisfaction with educational facilities and feeling comfortable in the classroom can affect learning, focus, and productivity, the necessity for a valid and reliable questionnaire that is appropriate for determining students’ satisfaction with training chairs has been recognized. Therefore, we aimed to design and validate a training chair satisfaction questionnaire.Materials and Methods: This descriptive study was performed in two phases, that is, designing and examining the validity and reliability of the satisfaction questionnaire and determining its cut-off point in 2016. To determine the content validity of the questionnaire, content validity ratio (CVR) and content validity index (CVI) were used, and to determine its external and internal reliability, test-retest and Cronbach's alpha methods were adopted. Also, the receiver operating characteristic (ROC) curve was utilized for specifying its sensitivity, specificity, and cut-off point.Results: CVI was calculated at 0.798, which is acceptable for this questionnaire. Cronbach's alpha coefficient was estimated at 0.799 and the correlation between the questions in first and second series was in an acceptable significance level (r=0.825; P=0.000). In the ROC, the cut-off point was reported as 35.5 with the sensitivity and specificity of 80.9% and 46.2%, respectively, and area under the ROC curve at this cut-off point was 0.65.Conclusion: Based on our results regarding the validity and reliability indices of the questionnaire developed by the researcher, it was noted that this questionnaire is valid and reliable for the assessment of students’ satisfaction with training chairs and can be used to examine all office and student chairs.

Background and Objective: Constant exposure to cold is considered a workplace hazard in cold seasons. We aimed to determine the level of cold stress and its relationship with physiological responses in auto mechanics.Materials and Methods: This analytical cross-sectional study was conducted in the winter of 2016 among auto mechanics in Hamadan, Iran. Physiological responses were measured in accordance with the ISO 9886 standard method. Body fat percentage was also quantified using Caliper model 01128, and the thermal resistance of the participants’ clothing was calculated in clousing the ISO 9920 standard. Environmental measures such as air temperature and air velocity were measured simultaneously, based on which cold stress indices including wind chill factor and wind chill equivalent temperature were determined. Data were analyzed using SPSS, version 21.Results: The means of wind chill index, equivalent chill temperature, and minimal required clothing insulation (IREQ) were 489.97±47.679 kcal/m2.h, 13.78 ± 1.869oc, and 2.04±0.246 clo, respectively. According to the results of cold stress indices, the studied employees were exposed to cold stress.Pearson correlation test reflected a significant relationship between cold stress indices and physiological responses (P<0.05), however, IREQ showed the highest association with the physiological responses of the subjects. Moreover, there was a significant correlation between body fat percentage and core temperature (P<0.05; r=0.314).Conclusion: The results confirmed that IREQ index has high validity for the estimation of cold stress among auto mechanics. Moreover, the increase of body fat percentage boosts cold tolerance of employees.

Background and Objective: Grip and pinch strength is a measure indicating the function of hand and is considered as a sign of general health. Work-related musculoskeletal disorders (WMSDs) are highly prevalent due to the incongruity of work with the workers. However, the diseases caused by such incongruity are preventable. Regarding this, the present study was conducted with the aim of investigating the relationship of maximum oxygen uptake (Vo2max) with grip and pinch strength and endurance.Materials and Methods: This cross-sectional study was conducted on 120 male assembly workers using simple random sampling technique. The Vo2max, grip endurance and strength, as well as pinch endurance and strength were assessed by means of step test, dynamometer, and pinch gauge, respectively. The grip endurance was specified through determining the maximum time (in seconds) that one could continue applying one third of the maximum voluntary contraction. Data analysis was carried out using Pearson correlation coefficient in SPSS 20. P-value less than 0.05 was considered statistically significant.Results: According to the results, Vo2max had a direct relationship with grip and pinch strength and endurance (P<0.05). Furthermore, Body Mass Index, age, and height showed a direct relationship with grip and pinch strength and Vo2max (P<0.05). However, grip endurance demonstrated no significant relationship with BMI and height (P>0.05). Additionally, there was a direct relationship between age and the endurance of grip and pinch (P<0.05).Conclusion: As the findings indicated, in order to prevent WMSDs and enhance occupational efficiency, the individuals with high Vo2max should be employed in the jobs requiring high grip and pinch strength and endurance.

Background and Objective: Inadequate lighting is among the most important factors causing non-ergonomic conditions in the beauty salons. The current study was carried out to evaluate the lighting and its relationship with occupational body postures in women's hair salons.Materials and Methods: This analytical cross-sectional study was conducted on 100 women working in 50 women's hair salons in Hamadan, Iran, in 2015. The measurement of general and local lighting intensity was performed according to the patterns and guidelines of the Ministry of Health. The horizontal and perpendicular lighting of the work surface was estimated using Hagner Digital Luxmeter, model EC1. In addition, the body posture of the participants was evaluated using the Rapid Entire Body Assessment method. Data analysis was performed using SPSS 21.Results: According to the results, the intensity of general and local lighting was lower than the mandatory OEL level of Iran in 72% and 97% of the hair salons, respectively. Postural evaluation showed that 26% and 12.5% of the people were at high and very high risk, respectively. Furthermore, a significant correlation was observed between the intensity of general lighting and posture risk score for eyebrow and face trimming activities (P<0.05).Conclusion: As the findings indicated, inadequate natural lighting, inappropriate design, and insufficient number of light sources have brought about an inappropriate lighting condition in most of the women's hair salons both quantitatively and qualitatively. Inadequate general lighting increased the posture risk score of the participants. Consequently, given the ergonomic risk level, it is necessary to make some modifications in the artificial lighting system of these places.

Background and Objective: Currently, musculoskeletal disorders (MSD) are one of the most common causes of occupational injuries and disability in industrialized and developing countries. MSDs impose heavy economic burdens that not only affect individuals, but also organizations and community. It is worth mentioning that the rapid entire body assessment (REBA) method is designed to assess occupations with dynamic or static postures and is used for assessing the risk of MSDs.Materials and Methods: This interventional study was conducted in the sliding gate and plastering stations of a steel company. To assess workers’ postures, the REBA and ManTRA techniques were applied before and after the intervention, and for ergonomic intervention, corrective engineering measures were implemented.Results: The findings showed a 63% and 64% reduction in the risk level at the plastering and sliding gate stations using the REBA technique and a 47% and 56% reduction in the ManTRA cumulative risk score at the plastering and sliding gate stations. In addition, data analysis showed a significant difference in the ultimate risk level scores in the REBA and ManTRA techniques before and after the intervention (P=0.001).Conclusion: The simultaneous use of the ManTRA and REBA techniques is beneficial for occupations involving manual activities in addition to the entire body involvement; activity duration is also important in these techniques. It should be noted that the limitations of each method will be minimized using the other technique.

Background and Objective: Probabilistic risk assessment through fault tree analysis is an effective tool to estimate the probability of hazardous event occurrence in chemical process industries. The probability of failure occurrence for basic events is not often available in process industries. The aim of this study was to calculate the basic event failure occurrence probability when these events have no precise failure data.Materials and Methods: In this study, the proposed risk assessment framework was based on two fuzzy-based approaches, including five and six scales. Firstly, the fault tree diagram was constructed using the risk identification methods. Subsequently, the failure occurrence probability of the basic events were calculated by applying the two types of failure possibility distributions. Finally, the critical minimal cut sets were ranked using the importance measure analysis.Results: According to the results, the failure occurrence probabilities calculated by the five-scale and six-scale approaches for the 32 basic events were closed to each other. The occurrence probability of the top event calculated by the five-scale and six-scale approaches were 3.64E-04 and 4.76E-04 per year, respectively. After ranking the minimal cut sets based on their calculated importance measures, the process failures were determined as the critical causes of top event.Conclusion: As the findings indicated, the fuzzy-based approach seems to be a good alternative for the conventional Fault tree analysis approach for dealing with the basic events, which have no failure rate data for obtaining the failure occurrence probabilities. This study confirmed the consistency of fuzzy-based approach for the assessment of the basic event failure occurrence probabilities.

Background and Objective: Globally, increasing participation of women in the labor market is one of the most important social phenomena. Currently, an exponential number of pregnant mothers are working in industries in the developing countries. In this study, we aimed to analyze all the articles that examined the complications of occupational noise exposure among women.Materials and Methods: The required data were collected from the international databases such as ScienceDirect, Scopus, ISI, and PubMed, and from the national databases including IranMedex, Magiran, and SID during 1980-2016. We performed the search using the following “occupational exposure”, “women”, “noise effects”, and “pregnancy”.Results: Studies have shown differences in hearing loss and the description of tinnitus between men and women. Some studies have proposed that the effect of noise, as a risk factor for the incidence of ischemic heart disease and changes in plasma cortisol level, is significantly higher in women than in men. In addition, by causing some changes in maternal endocrine system, noise exposure during pregnancy can lead to fetal growth restriction and acquired hearing loss in the baby. Hypertension, painful menstruation, hormonal disorders, and reduced fertility are among other complications of maternal noise exposure.Conclusion: Exposure to occupational noise, in addition to hearing loss and physiological effects, can have more consequences in women than in men in all circumstances, especially during pregnancy. Therefore, paying attention to the physiological and even psychological characteristics of women, especially pregnant women, in occupational health monitoring programs and periodic medical examinations is of great significance.

Background and Objective: Exposure to noise has harmful effects on physical and mental health as well as the function. Low frequency sound is one of the most important sources of noise in the environment. Some individual differences, such as extroversion, neuroticism, and sound sensitivity are among the factors influencing the effect of sound on cognitive functions. Therefore, this study aimed to investigate the effect of personality type (introversion/extroversion) on cognitive performance in the presence of low frequency noise.Materials and Methods: This interventional study was performed on 120 students of Hamadan University of Medical Sciences. The samples were selected through purposeful sampling (60 extroverts and 60 introverts) and entered the study. The cognitive performance of the subjects was examined using the Integrated Visual and Auditory Continuous Performance test during the confrontation with sound. The data were analyzed by independent t-test and analysis of variance using the SPSS version 20.Results: Results of the present study demonstrate that low frequency sound negatively affects the components of cognitive performances. It was revealed that the cognitive performance declines with an increase of 50 to 70 dB in noise pressure (P<0.05). Furthermore, evaluation of the effect of personality type (introversion/extroversion) and gender indicated that the cognitive performance was significantly more affected in introverts and women, compared to the extroverts and men (P<0.05).Conclusion: The findings of this study showed that increasing in the sound level from 50 to 70 dB led in diminished cognitive performance. In addition, this negative effect is significantly more prominent in introverts and women, in comparison with the extroverts and men.