Department of Occupational Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
Department of Occupational Health Engineering, School of Public Health, Isfahan University of Medical Sciences, Isfahan, Iran.
BMC Public Health. 2020 Jun 3;20(1):837. doi: 10.1186/s12889-020-08874-4.
There is not a comprehensive heat stress index to screen the people susceptible to heat disorders and illnesses in hot workplaces. The present study was aimed to develop a personal heat strain risk assessment (PHSRA) index in workplaces and validate it.
This cross-sectional study was carried out on 201 Iranian male employees under various thermal conditions. At first, the demographical data of participants were gathered. After that, the heart rate and tympanic temperature of the subjects were carefully measured at times of 30, 60, and 90 min of starting the work. Environmental factors were measured simultaneously. The metabolism rate and insulation value of clothes were also estimated. At the end, a novel index of the heat strain was developed using structural equation modeling in AMOS and validated using linear regression analysis in SPSS.
Indirect effect coefficients of personal factors including age, body mass index, maximum aerobic capacity, and body surface area were equal to 0.031, 0.145, - 0.064, and 0.106, respectively. The coefficients of main factors including dry temperature, wet temperature, globe temperature, wind speed, metabolism, and clothing thermal insulation were obtained as 0.739, 0.688, 0.765, 0.245, 0.482, and 0.383, respectively. These coefficients and normalized values of the factors were used to develop a novel index. The total score of the index was categorized into four levels by optimal cut-off points of 12.93, 16.48, and 18.87. Based on the results of regression analysis, this index justifies 77% of the tympanic temperature as a dependent variable (R = 0.77).
In general, the results indicated that the novel index developed by the personal and main factors had proper validity in the prediction of thermal strain.
目前尚无综合热应激指数来筛查高温作业场所易患热相关疾病和障碍的人群。本研究旨在开发一种工作场所个人热应激风险评估（PHSRA）指数并对其进行验证。
本横断面研究共纳入 201 名伊朗男性员工，他们在不同的热环境下工作。首先收集参与者的人口统计学数据，然后在工作开始后 30、60 和 90 分钟测量受试者的心率和鼓膜温度，同时测量环境因素，估算代谢率和衣服的隔热值。最后，使用 AMOS 中的结构方程建模开发一种新的热应激指数，并使用 SPSS 中的线性回归分析进行验证。
个人因素（年龄、体重指数、最大有氧能力和体表面积）的间接效应系数分别为 0.031、0.145、-0.064 和 0.106。主要因素（干球温度、湿球温度、全球温度、风速、代谢和服装隔热）的系数分别为 0.739、0.688、0.765、0.245、0.482 和 0.383。这些系数和因素的归一化值被用于开发一个新的指数。通过最优截断点 12.93、16.48 和 18.87，将指数的总得分分为四个等级。基于回归分析的结果，该指数可以解释鼓膜温度的 77%（R=0.77）。
总的来说，个人和主要因素共同开发的新指数在预测热应激方面具有适当的有效性。
