Study on Evaluation Index of Physical Load of Chemical Prevention Personnel in High Temperature and Humidity Environment

Abstract

AbstractChemical protection personnel need to wear closed clothing to work in harsh environment. Continuous sweating and outward heat dissipation will lead to high temperature and high humidity inside the chemical protection clothing, which will increase the physical load of chemical protection personnel. In the environment of high temperature and humidity for a long time, the thermoregulation function of chemical prevention personnel is easy to be maladjusted, such as heat stroke, heat spasm, heat failure, etc., which will lead to vague consciousness and even shock. Therefore, accurate monitoring and evaluation of the physical load of chemical protection personnel in high temperature and humidity environment is very important to optimize the operation process and ensure the safety of workers. Firstly, the temperature and humidity of the environment were controlled by simulation experiment, and the core temperature, surface skin temperature, heart rate, blood oxygen, sweating amount and sweat evaporation amount were measured when the chemical protection personnel were wearing chemical protective clothing. The change rules of each index were studied by using statistical analysis method, and the sensitive physical load evaluation index was revealed. Then, the weight coefficient of each index is calculated based on factor analysis method to simplify the independent variable factors of physical load evaluation model. Finally, the regression model of physical load was constructed by combining subjective feelings and physiological indexes. Sixteen healthy men aged 19–25 years participated in the test. The environment temperature and humidity were divided into normal temperature and humidity (23 ℃, 45%), low temperature and high humidity (10 ℃, 70%) and high temperature and humidity (35 ℃ and 60%). The core temperature was measured by anus and Cor-temp capsule temperature sensor. The results showed that the core temperature of chemical prevention personnel in normal temperature and humidity environment was relatively stable, while the core temperature in low temperature and high humidity, normal temperature and high humidity environment increased by 0.74 ℃, 1.03 ℃ and 2 ℃ respectively. There was significant difference in the core temperature of chemical prevention personnel under different temperature and humidity environment (P < 0.05), which proved that the core temperature can be used as a sensitive index to evaluate physical load. The surface skin temperature of shoulder, chest, arm, waist, neck, hand, thigh and lower leg was measured by temperature inspection instrument. The results showed that the surface skin temperature of chemical protection personnel in high temperature and humidity environment increased significantly (up to 39 ℃). There were significant differences in the skin temperature of chemical protection personnel under different temperature and humidity conditions (P < 0.05), indicating that the surface skin temperature can be used as a sensitive index to evaluate physical load. The heart rate data were measured using the ECG band developed by polar team. The results showed that the heart rate of the chemical protection personnel wearing protective clothing was the fastest (up to 180 bpm) in high temperature and humidity environment. There was significant difference in heart rate under different temperature and humidity (P < 0.05), which proved that heart rate can be used as a sensitive index to evaluate physical load. The blood oxygen saturation was measured by finger cuff sensor. The results showed that the oxygen saturation of the chemical protection personnel in the normal temperature and humidity environment was 95%, and the oxygen saturation of the chemical protection personnel wearing protective clothing in the low temperature and high humidity environment, the normal temperature and normal humidity environment and the high temperature and high humidity environment decreased gradually, which were 94%, 93% and 91%, respectively. There was significant difference in blood oxygen saturation among chemical workers under different temperature and humidity (P < 0.05), which proved that blood oxygen saturation could be used as a sensitive index to evaluate physical load. The results showed that the amount of sweat and evaporation increased with the increase of ambient temperature. The average sweating amount was 1.25 kg, accounting for 1.6% of body weight, which reached the limit of human sweating capacity. There were significant differences in the amount of sweat and the amount of sweat evaporation in different temperature and humidity environment (P < 0.05), which proved that the amount of sweat and the amount of sweat evaporation can be used as a sensitive index to evaluate the physical load. The weight coefficient obtained by factor analysis showed that the temperature index was the most important indexes in the evaluation of physical load in high temperature and humidity environment. There are two key factors, core temperature and heart rate, in the stepwise regression equation of physical load established between subjective feelings and sensitive indicators. The fitting degree of the model is as high as 0.917 under the hypothesis test of homogeneity of variance.KeywordsChemical protection personnelPhysical loadEvaluation indexHigh temperature environmentHigh humidity environment