Development and validation of an environmental heat strain risk assessment (EHSRA) index using structural equation modeling based on empirical relations

BACKGROUND@#Need to a simple, available, accurate, comprehensive, and valid indicator is felt to assess thermal effects. Therefore, the present study was aimed to develop and validate the environmental heat strain risk assessment (EHSRA) index using structural equation modeling (SEM) based on empirical relations.@*METHODS@#This cross-sectional study was performed on 201 male workers in environments with various climatic conditions. The heart rate and tympanic temperature of the individuals were monitored at times of 30, 60, and 90 min after beginning the work. At these times, values of dry temperature, wet temperature, globe temperature, and air velocity were also measured and metabolism rate and clothing thermal insulation value were estimated. At the end, a theoretical model was depicted in AMOS software and obtained coefficients were applied to develop a novel index. The scores of this indicator were categorized into four risk levels via ROC curves and validate using linear regression analysis.@*RESULTS@#Indirect effect coefficients of the globe temperature, dry temperature, wet temperature, air velocity, metabolism, and clothing thermal insulation variables on the tympanic temperature were computed by 0.77, 0.75, 0.69, 0.24, 0.49, and 0.39, respectively. These coefficients were applied to develop the index. Optimal cut-off points of boundaries between risk levels included 12.02, 15.88, and 17.56. The results showed that the EHSRA index justified 75% of the variations of the tympanic temperature (R@*CONCLUSIONS@#The novel index possesses appropriate validity. It was suggested that this indicator is applied and validated in various environments in the next studies.

The relationship between illnesses and medical drug consumption with the occurrence of traffic accidents among truck and bus drivers in Tehran, Iran / 中华创伤杂志(英文版)

PURPOSE@#To determine the relationship of illnesses and medical drug consumption with the occurrence of traffic accidents among truck and bus drivers.@*METHODS@#This is a cross-sectional study on truck and bus drivers in Tehran, Iran. The criteria for participating in this study were: married males over 30 years old, driving license in grade one, five years of job experience, mental health and non-addiction license. The criterion for not participating in this study was the lack of cooperation in responding to the questions. Six months was spent to collect the latest five years data of driving accidents from 2011 to 2016. A total of 323 truck and bus drivers in Tehran city and the suburbs, Iran were chosen. Among them, 112 were responsible for accidents (accident group) while 211 were not responsible for any accidents or involved in an accident in the last five years (non-accident group). A specially designed questionnaire was used to investigate the demographic information, medical drug consumption, medical backgrounds and history of accidents.@*RESULTS@#The results revealed that compared with healthy subjects, the occurrence of accidents among people with diabetes (OR = 2.3, p = 0.001) and vision weakness (OR = 1.7, p = 0.020) was significantly higher, while that among people with cardiac (OR = 0.5, p = 0.002) and hypertension (OR = 0.9, p = 0.048) problems was remarkably lower. Moreover, consumption of Gemfibrozil (OR = 1.8, p = 0.010) and Glibenclamide (OR = 2.2, p = 0.002) drugs resulted in significantly higher incidence of accidents than those without.@*CONCLUSION@#Frequencies of illnesses like cardiovascular and hypertension were not higher in accident drivers than in non-accident drivers; but diabetes, vision weakness and consumption of Gemfibrozil and Glibenclamide lead to more traffic accidents.

Prevalence hearing loss of truck and bus drivers in a cross-sectional study of 65533 subjects

BACKGROUND@#Noise pollution is one of the most important occupational pollutants in heavy-vehicle drivers. Therefore, this epidemiological research was conducted with the aim of determining the prevalence of hearing loss in heavy-vehicle drivers in Iran.@*METHODS@#This cross-sectional research was conducted on 65,533 heavy-vehicle drivers including truck and intercity bus drivers from February 2006 to March 2016. The air and bone threshold of pure tone was measured for each ear at 0.5, 1, 2, 3, 4, 6, and 8 kHz by a skillful radiology expert. The obtained data from this research was analyzed in SPSS software using statistical tests such as descriptive analysis and paired t test.@*RESULTS@#Mean (standard deviation) of hearing loss in left and right ears of all people was 23.02 (8.25) and 22.48 (7.86), respectively. Paired t test showed that hearing loss difference in left and right ears was significant (P < 0.001). Mean and standard deviation of paired t test showed that hearing loss difference in left and right ears was significant in all frequencies except 1000 Hz (P < 0.001).@*CONCLUSION@#The findings of this research generally showed that 26.8% of the studied drivers have hearing loss. Hearing loss in the left ear was more than right ear.

Comparison of the Impact of an Optimized Ice Cooling Vest and a Paraffin Cooling Vest on Physiological and Perceptual Strain

BACKGROUND: Ice cooling vests can cause tissue damage and have no flexibility. Therefore, these two undesirable properties of ice cooling vest were optimized, and the present study was aimed to compare the impact of the optimized ice cooling vest and a commercial paraffin cooling vest on physiological and perceptual strain under controlled conditions. METHODS: For optimizing, hydrogel was used to increase the flexibility and a layer of the ethylene vinyl acetate foam was placed into the inside layer of packs to prevent tissue damage. Then, 15 men with an optimized ice cooling vest, with a commercial paraffin cooling vest, and without a cooling vest performed tests including exercise on a treadmill (speed of 2.8 km/hr and slope of %0) under hot (40℃) and dry (40 %) condition for 60 min. The physiological strain index and skin temperature were measured every 5 and 15 minutes, respectively. The heat strain score index and perceptual strain index were also assessed every 15 minutes. RESULTS: The mean values of the physiological and perceptual indices differed significantly between exercise with and without cooling vests (P 0.05). CONCLUSIONS: The optimized ice cooling vest was as effective as the commercial paraffin cooling vest to control the thermal strain. However, ice has a greater latent heat and less production cost.

The effect of increasing the illumination on operators' visual performance in the control-room of a combined cycle power plant

BACKGROUND: Lighting is one of the environmental factors affecting the performance of the control room operators. Therefore, the aim of this study was to compare the control room operators’ visual performance in two different illumination conditions at a combined cycle power plant through field-work. METHODS: Sixteen operators in day shift were evaluated with the Freiburg Visual Acuity test (FrACT) software at two lighting systems with different intensities. It includes the first phase with fluorescent illumination system (Power: 40 W, Color Temperature: 4000 Kelvin, Luminous Flux: 2780 Lumen and Model: Pars Shahab) and the second phase with a combined illumination system includes fluorescent and LED (Power: 48 W, Color Temperature: 4000 Kelvin, Luminous Flux: 5400 Lumen and Model: Mazinoor). RESULTS: Based on the results, visual performance index and visual acuity significantly increased after the intervention (p < 0.001). As to contrast, more lighting significantly reduced the percentage of recognized contrast (p < 0.001) and increased the contrast performance index (p < 0.001). CONCLUSIONS: The results of this study showed that increasing the intensity of light from the values below the allowable limit to the values above the allowable limit would increase the visual indicators in individuals.