Study On The Inhalation Exposure Characteristics Of Human Based On The Breathing Thermal Manikin

With the development of China’s economy and the energy consumption in the form of coal combustion,the increase of industrial emissions and use of motor vehicle,China has become one of the countries with the most serious air pollution in the world.In the latest“Global Disease Burden”（GBD）study,the lancet pointed out that air pollution has increased the mortality and incidence rate of human beings^[1].Only in 2015,the Global Burden of Disease study revealed that approximately 1.1 million people died prematurely and 21.8 million disability-adjusted life-years（DALY s）were lost because of ambient air pollution in China in 2015^[2].PM2.5 is the fourth health risk factor in China^[3],the harm of PM2.5 pollution to the respiratory system has posed a serious threat to the health of Chinese Residents.However,there is a lack of research on the health effects of individual level fine particle exposure in developing countries,including China.The actual risk of infection depends on the actual exposure dose of particles in the respiratory tract,not the average exposure of particles in the indoor environment.Therefore,it is of great significance to evaluate the exposure of particulate matter in breathing zone and respiratory tract from an individual perspective.We developed a new type of breathing thermal manikin,reconstructed the complex structure of mouth-pharynx-larynx-respiratory tract.It is the first time to realize the combination of breathing thermal manikin and respiratory model.The breathing thermal manikin is similar to the average human body in shape.By adjusting the output power of the heating system,its can simulate the metabolic heat dissipation of the human at various activities.The"ideal respiratory model"is embedded to reappear the movement state of the inhaled airflow in the respiratory system.We independently developed the breathing simulator to improve the authenticity of the respiratory curve.By adjusting respiratory parameters,it can simulate the respiratory characteristics of human in different activities.The breathing breathing thermal manikin can reappear of human micro-environment under the synthetic effect of human thermal plume and respiratory airflow,effectively measure the actual exposure dose of particles in the human respiratory tract,and carry out the research of inhalation exposure characteristics instead of human.Based on the breathing thermal manikin,the temperature and heat transfer coefficient of the body surface were measured,the velocity distribution of the boundary layer of the body and the breathing microenvironment,and the trajectory of the exhaled airflow were studied.The results show that when the metabolic rate of the manikin is1.2met,the body surface temperature is in the range of 29.1℃～31.1℃,the overall temperature difference is less than 2℃,and the fluctuation is small.The whole weighted convective and radiative heat transfer coefficients of the manikin surface are consistent with the standard wind tunnel test data in the literature,and the difference is less than 6%.Therefore,the manikin can produce a temperature distribution close to the human body,which can be used to simulate the heat dissipation characteristics of human.The velocity of the microenvironment field of the manikin decreases with the increase of the distance from the human body surface;the velocity of the airflow increases in the direction of body height,reaching the maximum in the chest position;in agreement with the published literature data.The influence range of the exhaled air flow increases with the increase of the respiratory intensity.The results show that the breathing thermal manikin can simulate human micro-environment scientifically.On the one hand,it can improve the geometric accuracy of human body surface,reconstruct the complex structure of mouth-throat-respiratory tract,so as to improve the airflow distribution near the manikin and in the respiratory tract;on the other hand,it can improve the authenticity of the respiratory simulation device to simulate the respiratory curve of the human body,and more accurately measure the effective dose of pollutants inhaled into the specific parts of the respiratory tract.Based on the breathing thermal manikin,the effects of human thermal plume and respiratory intensity on the actual exposure level of human body and the evolution of particulate matter exposure in the environment-breathing zone-respiratory tract were studied.The results showed that under the condition of short-range exposure,plume had a protective effect on human body,reducing the particle concentration in the breathing zone by 28.5%;the respiratory intensity significantly affected the particle exposure level in the breathing zone and respiratory tract.When the respiratory intensity increased from10L/min to 14L/min,the particle concentration in the breathing zone increased by 18.1%,and the actual exposure dose of oropharyngeal terminal and bronchus below grade5（hereinafter referred to as the lower respiratory tract）in the respiratory tract increased by 115%and 147%,respectively.Based on the concentration of particulate matter in the air outlet,the ratio of environment-breathing zone-oropharyngeal terminal-the lower respiratory tract was 1.0:4.7:3.2:2.3.