Research On Human Body Thermal Response Of Outdoor Workers Under High Temperature

With the global warming,the hot weather in summer increases year by year.At the same time,the high-density population,buildings and the continuous traffic network in cities aggravate the severity of the thermal environment in cities,causing serious threats to human health.About 50%of the cases of heat stroke in high temperature are outdoor workers,so it is very important to study the thermal response of outdoor workers under high temperature to avoid heat stroke and other thermal injuries caused by high temperature environment.Due to the particularity of the nature of their work,traffic police inevitably need to be exposed to outdoor high temperature environment in a certain period of time,and they cannot change their clothes and surrounding micro-environment at will,so they are vulnerable to heat damage from high temperature environment.Taking tianjin traffic police in a cold region as an example,this paper carried out a study on human thermal response under outdoor high temperature in summer.The main research contents and results are as follows:First,in view of the lack of thermal performance parameters of traffic police uniforms in the analysis of thermal response of personnel in high temperature outdoor,this paper measured and analyzed the thermal resistance and humidity resistance of traffic police uniforms in tianjin through"Walter",the sweat warm body dummy and the artificial climate room.The results showed that the measured thermal resistance value of the traffic police uniform was 0.628clo,10.2%higher than the recommended thermal resistance value in ASHRAE and 25.6%higher than the recommended thermal resistance value in ISO.The moisture permeability index of the traffic police uniform was 0.242,32.8%lower than the recommended moisture permeability index value in ASHRAE.It indicates that the thermal performance parameters of tianjin traffic police uniforms do not meet the requirements of international standards.The thermal property measurement experiment of clothing fabric shows that the thermal resistance of clothing fabric is higher than that of clothingSecondly,the field measurement of outdoor working environment parameters of tianjin traffic police in summer and the subjective investigation of traffic police's thermal response were carried out,and the potential relationship between the thermal response and environmental parameters during traffic police's duty was studied and analyzed by using linear regression method.It was found that there was a significant linear relationship between human thermal sensation and outdoor air temperature,and the correlation coefficient R~2reached 0.976(June)and 0.982(July),respectively.When PMV model is applied to outdoor unsteady thermal environment,it will overestimate the actual thermal sensation value of human body by 3%?36%.The binary linear relationship between sweat,body state and physical state and air temperature and time was obtained,and the correlation coefficient R~2was up to 0.826?0.965.Thirdly,combining the thermal parameters of traffic police clothing and outdoor environment parameters in summer,the two-node model of Gagge was used to simulate the changing trend of physiological parameters over time and the heat exchange with the environment in the actual work of outdoor traffic police station under high temperature.The results showed that the human physiological parameters were still within the safety limit on the test day in June.The core temperature in the161st and 66th minutes of the morning shift and afternoon shift on the test day of July had reached the upper limit of human tolerance in high temperature environment(38?)stipulated in ISO 7933 standard,and the average skin temperature in the 137th minute of the afternoon shift had reached the upper limit of body surface temperature tolerance stipulated in ISO 9886 standard(38.8?).The conclusion will provide reference for the traffic police on duty schedule and help to reduce the thermal injury of outdoor workers.