Validation of Physiological Strain Index Based on Heart Rate in Experimental Hot Conditions

Heat stress is a common problem in industrial workplaces. Thermal stress is a caused reduces concentration of and fatigue increases individuals and thermal condition can be one of accident risk factors .The purpose of this study was validation of Physiological Strain Index Based on Heart Rate in experimental condition. This Semi experimental study was conducted to 16 male in five different temperature conditions (21, 24,27,30,35ºC) in the climate chamber and on the treadmill with two levels of activity 2.4 kph (light physical activity) and 4.8 kph (medium physical activity).Heart rate was measured to for calculating Physiological Strain Index Based on Heart Rate, rate perceived exertion and questionnaire Heat Strain Score index was measured. The correlations between the indices were evaluated using Pearson correlation test and regression analysis. Pearson correlation test showed a significant correlation between Physiological Strain Index Based on Heart Rate and rate perceived exertion (p≤0.001,r=0.96).also a high correlation was observed between Physiological Strain Index Based on Heart Rate and wet bulb globe temperature (p≤0.001,r=0.90). A very high correlation was observed between Physiological Strain Index Based on Heart Rate and Heat Strain Score Index (p≤0.001, r=0.93). The results of this study showed Physiological Strain Index Based on Heart Rate a suitable method for strain heart evaluation is caused by thermal stress because there was an acceptable correlation with heat stress valid indices

Designing and validation a visual fatigue questionnaire for video display terminals operators

Background: Along with the rapid growth of technology its related tools such as computer, monitors and video display terminals (VDTs) grow as well. Based on the studies, the most common complaint reported is of the VDT users. Methods: This study attempts to design a proper tool to assess the visual fatigue of the VDT users. First draft of the questionnaire was prepared after a thorough study on the books, papers and similar questionnaires. The validity and reliability of the questionnaire was confirmed using the content validity index (CVI) beside that of the Cronbach's Coefficient Alpha. Then, a cross-sectional study was carried out on 248 of the VDT users in different professions. A theoretical model with four categories of symptoms of visual fatigue was derived from the previous studies and questionnaires. Having used the AMOS16 software, the construct validity of the questionnaire was evaluated using the confirmatory factor analysis. The correlation co-efficiency of the internal domains was calculated using the SPSS 11.5 software. To assess the quality check index and determining the visual fatigue levels, visual fatigue of the VDT users was measured by the questionnaire and visual fatigue meter (VFM) device. Cut-off points were identified by receiver operating characteristic curves. Results: CVI and reliability co-efficiency were both equal to 0.75. Model fit indices including root mean of squared error approximation, goodness of fit index and adjusted goodness of fit index were obtained 0.026, 0.96 and 0.92 respectfully. The correlation between the results measured with the questionnaire and VFM-90.1 device was-0.87. Cut-off points of the questionnaire were 0.65, 2.36 and 3.88. The confirmed questionnaire consists of four main areas: Eye strain (4 questions), visual impairment (5 questions) and the surface impairment of the eye (3 questions) and the out of eye problems (3 questions). Conclusions: The visual fatigue questionnaire contains 15 questions and has a very remarkable validity and reliability. Usingthis questionnaire and its findings, one will be able to identify, assess and finally prevent the effective factors of VDT users' visual fatigue

Relationship between Lighting and Noise Levels and Productivity of the Occupants in Automotive Assembly Industry

Work environment affects human productivity and his performance. The aims of this study were to investigate the effects of lighting and noise levels on human productivity in the automotive assembly industry. Method. Subjects were 181 workers from different parts of an automobile assembly industry. Illuminance (Lx) at the height of 30 inches from the surface of work station and noise (dBA) were locally measured. Also human productivity by the Goldsmith and Hersey scale (1980) was measured. Data were analyzed by using SPSS v20 Pearson correlation coefficient. Results. The results showed that the relationship between noise level and human productivity is negative and significant (, ), but there was no significant relationship between lighting and human productivity (). Conclusion. Based on the results, in assembly tasks, noise has a negative impact on human productivity, and lighting does not affect this. So, in order to increase employee productivity, noise control and reduction to less than the standard values (less than 85 dB) is necessary

Prevalence of Impacted Teeth among Young Adults: A Retrospective Radiographic Study

Objectives: The prevalence of impacted teeth fluctuates across various ethnicities and geographical regions. The aim of the present study was to evaluate the prevalence and patterns of impacted teeth among patients living in the central part of Iran. Methods: This retrospective study was conducted on 3632 patients within the age group of 17-30 years. The frequency and pattern of the impaction were determined using orthopantomogram (OPG). Results: According to the results of the study, 56.3% of the patients were female (n=2046). Out of the 3632 OPGs, 1602 cases (44.1%) were detected with at least one impacted tooth. No significant difference was observed between the males (n=682; 42.6%) and females (n=920; 57.4%) in this regard (P=0.237). Furthermore, the third molars were the most common impacted teeth found in 1156 radiographs (31.8%) with no significant difference between the males (n=358; 30%) and females (n=798; 70%) (P=0.386). Mesioangular and distoangular impactions were detected to be the most frequent angulation of the impacted third molars in the mandible (49%) and maxilla (41%), respectively. Additionally, 357 (9.8%) and 78 (2.1%) cases showed at least one impacted maxillary canine and one impacted mandibular second premolar, respectively. Moreover, impacted ectopic teeth were observed in 11 (0.3%) individuals. Conclusion: Based on the findings of the present study, the third molar was the most common impacted tooth observed in the people living in the central region of Iran, followed by canine and second premolar impaction. The prevalence of the third molar impaction in the females was nearly twice as much as that in the males

Oral Temperature Changes among Overweight and Normal-Weight Subjects during Exercise under Hot Climatic Conditions

The overweight and obesity are considered as a risk factor for the heat strain. This study was planned to assess the oral temperature changes among overweight and normal-weight subjects during light and moderate exercises under exposure to hot and very hot conditions. An experimental study was conducted on 35 subjects with normal-weight and 35 subjects who had overweight. The subjects rested for 30 minutes. Then, each subject performed a light exercise (2.8 kilometers per hour on the treadmill) under exposure to very hot and moderately humid conditions for 60 minutes. In the next phase, subjects performed a moderate exercise (4.8 kmph on the treadmill) under exposure to hot and moderately humid conditions for 60 minutes after 30 minutes of rest. The oral temperature was measured every 4 minutes. The rest oral temperature of overweight subjects with body mass index more than 27kg/m2 was significantly higher than that of normal-weight subjects in both conditions (

Comparing the Effect of Two Portable Cooling Vests on Physiological Parameters under Hot Laboratory Conditions

Personal protective clothing (PPC) can cause heat strain. The purpose of this study was Heat strain control by two portable cooling vests under wearing vapor protective suit and hot condition. An experimental study was conducted in a climatic chamber on 15 male students under warm conditions (ambient temperature =40°C, relative humidity=40%). Each participant performed the test without a cooling vest and with Spadana (Of 70% cotton and 30% polyester with 10 pockets for PCM: Hydrogel packages and a total weight of 2.3kg) and Techkewl-7026 (100% cotton with 4 pockets for PCM packages and a total weight of 2 / 2kg) phase change material cooling vests. The activity rate on a treadmill was light (2.8km/h) and the test lasted 30 minutes for each stage. Cooling effects were evaluated by measuring heart rate, oral temperature and skin temperature. Results showed that the mean and standard deviation for heart rate, oral temperature and skin temperature with a Spadana cooling vest were 100.55 (8.12)(bpm), 36.83 (0.25)°C and 31.52(1.85)°C, respectively, and for Techkewl-7026 cooling vests were 103.64 (10.9)(bpm), 36.98(0.34)°C and 34.2 (1.4)°C, respectively, and for without cooling vest were 113.33(11.23)(bpm), 37.05(0.35) °C and 37.93(0.48) °C, respectively . The difference between parameters with cooling vests and without cooling vest was statistically significant (p < 0.05). The use of Spadana and Techkewl-7026 phase change material cooling vests can reduce thermal stress through a reduction in heart rate, oral temperature, skin temperature and sweating rate

A Study of The Relationship Between The Components of The Five-Factor Model of Personality and The Occurrence of Occupational Accidents in Industry Workers

Accidents are among the most important problems of both the developed and the developing countries. Individual factors and personality traits are the primary causes of human errors and contribute to accidents. The present study aims to investigate the relationship between the components of the five-factor model of personality and the occurrence of occupational accidents in industrial workers. The independent T-test indicated that there is a meaningful relationship between the personality traits and accident proneness. In the two groups of industry workers injured in occupational accidents and industry workers without any occupational accidents, there is a significant relationship between personality traits, neuroticism (p=0.001), openness to experience (p=0.001), extraversion (p=0.024) and conscientiousness (p=0.021). Nonetheless, concerning the personality trait of agreeableness (p = 0.09), the group of workers with accidents did not differ significantly from the workers without any accidents. The results showed that there is a direct and significant relationship between accident proneness and the personality traits of neuroticism and openness to experience. Furthermore, there is a meaningful but inverse correlation between accident proneness and the personality traits of extraversion and conscientiousness, while there was no relationship between accident proneness and the personality trait of agreeableness

The Impact of Hearing Protection Devices (HPDs) on Blood Pressure in Workers Exposed to Noise: A Cross-sectional Study in a Textile Industry

Many studies have reported that exposure to workplace noise leads to increase in blood pressure. The aim of this study was to investigate the effect of hearing protection devices (HPDs) including ear plug and ear muff on the systolic and diastolic blood pressures of workers exposed to workplace noise in a textile industry. A total of 120 male workers that exposed to 95 dB noise were investigated in this study. The systolic and diastolic blood pressures of the workers were measured for three situations of earplug, earmuff and earplug along earmuff applications. Data analyses were conducted through SPSS software (version 20) and statistical tests of ANOVA and Independent Sample Tests. The comparison of mean blood pressure in three situations showed that using ear muff had a significant effect on the systolic and diastolic blood pressures in the workers. Furthermore, the use of ear plug only had an effect on the systolic blood pressure. But, the application of ear muff caused to decrease in the systolic and diastolic blood pressures only in the third stage of the study. With regard to the results in this study, in order to control the blood pressure changes of the workers, it is recommended to use ear muff in the textile industry

Development of an observational-perceptual heat strain risk assessment (OPHSRA) index and its validation

Background The thermal strain can be measured using subjective methods without the use of sensitive equipment. The purpose of the present study was the development and validation of an observational - perceptual heat strain risk assessment (OPHSRA) method. Methods This cross-sectional study, in 2019, was performed. At first, an observational-perceptual questionnaire was designed using effective items in producing heat strain. Then, the reliability and validity of the questionnaire were examined. Later, 201 male workers were asked to perform the routine tasks for 90 min under various climatic conditions after resting in a cool room. At the end of the activity, the tympanic temperature of the subjects was accurately measured. Also, the designed questionnaire was completed by researchers and participants. Then, the effect coefficients of the items were calculated and used for developing the novel index. At final, the index validity was investigated. Results The values of the content validity ratio (CVR), content validity index (CVI), and Cronbach's coefficient alpha (alpha) of the designed questionnaire with 16 questions were equal to 0.793, 0.913, and 0.910, respectively. The results indicated that environmental, job, administrative, and clothing items assessed by the questionnaire with the coefficients of 0.860, 0.658, 0.783, and 0.566 had significant effects on the thermal strain, respectively. These coefficients were exploited to develop the index. The result revealed that the OPHSRA index justified 69% of the variations of the tympanic temperature (R-2 = 0.69). Conclusion The novel index developed by the questionnaire had an acceptable validity. Therefore, this index can be used for estimating the risk of thermal strain in a variety of thermal conditions

Investigating the Relationship between Heat Stress and Strain Indices with Human Productivity in Workers of a Steam Power Plant

injuries, losses, and reduced productivity. The aim of this study was to investigate the relationship between heat stress and strain indices with human productivity in workers of a steam power plant. Methods: This descriptive cross-sectional study was performed on 104 workers of a steam power plant in summer season. Two indices of Wet Bulb Globe Temperature (WBGT) and Heat Strain Score Index (HSSI) were used to measure heat stress and strain, respectively. Human productivity was also measured using Hersey and Goldsmit 26-item scale. Data were analyzed using analysis of variance (ANOVA) test and Pearson correlation coefficient. Findings: According to ANOVA results, there was no significant difference in WBGT in three heights of head, waist, and ankle. The highest value of WBGT index was related to the 4th floor boiler unit (27.3 ± 5.6) and the lowest value was related to the administrative unit (16.9 ± 3.5). The maximum and minimum values of HSSI were obtained for the 3th floor boiler unit (27.2 ± 0.4) and workshop facilities (12.0 ± 3.0), respectively. The highest and lowest values of human productivity was related to the welding (97.0 ± 25.9) and boiler (28.5 ± 2.8) units, respectively. The results of ANOVA analysis showed that the values of WBGT, HSSI indices, and productivity subscales in different units were significantly different (P < 0.05). Pearson correlation coefficient analysis showed that there was a significant inverse relationship between productivity and its subscales with the amount of heat stress and strain (P < 0.05). Conclusion: There is a negative relationship between productivity, heat stress, and strain. Therefore, to protect workers' health and productivity, precautionary measures should be taken, including an appropriate rest-work ratio, short working hours, fluid replacement, and engineering controls such as the use of efficient cooling methods such as air conditioning, fan, or cooling clothing