The Law Of Particle Inhalation And Deposition In The Respiratory Tract In High-polluting Environment: A Experimental And Numerical Investigation

Inhalable particulate matter has become the primary pollutant in high-polluting environments such as industrial buildings,which seriously endangers human health.Therefore,it is essential to investigate particle characteristics in high-polluting environments and study the law of particle inhalation and deposition in the human respiratory tract.In this paper,factory measurements,model experiments,and numerical simulations are used to study the factory environment and the level of particle inhalation and deposition in the respiratory tract.Besides,the respiratory behaviors and particle properties are analyzed to research their effects on the law of particle inhalation and deposition.Firstly,the particle concentration,particle size distribution,and metal composition in the factory particle are measured.Results show that most particles’sizes are less than 1μm and the particle concentration is between 190μg/m~3to 220μg/m~3in machining workshop.The concentration of particulate matter is high and fluctuates significantly over time due to the molding factory’s production process,which can change more than two times within a few minutes.The concentrations of metal elements in particulates in all workshops are higher than that in an ordinary atmospheric environment.Secondly,a respiratory tract model including the face and lung cavity is constructed to measure particle inhalation and deposition level in the machining workshop.Moreover,the total particle deposition fraction is obtained.A detachable-welded respiratory tract model is constructed to perform fluorescent particle inhalation and deposition experiments.The visual distribution and quantitative results of particle deposition are obtained.Results show that particle deposition number decreases firstly and then increases along the airflow direction.The particle deposition distribution in the entire respiratory tract shows a"V"-shaped curve.Then,the indoor-human-respiratory tract coupling model is constructed,which considers the influence of indoor airflow patterns and human thermal plume on the particle’s inhalation and deposition in the human respiratory tract.User-defined functions and dynamic mesh are used to show the periodic contraction and expansion of the respiratory tract.Finally,the airflow pattern,particle inhalation ratio,repeated inhalation ratio,particle deposition distribution,particle deposition fraction in the respiratory tract with different respiratory behaviors and particle properties are analyzed by numerical simulation.The simulation results show that the respiratory tract’s airflow is turbulent,and the airflow pattern will affect the particle inhalation and deposition in the respiratory tract.Compared with nasal respiration,the particle inhalation ratio,repeated inhalation ratio,and the number of particles depositing in the lower respiratory tract in oral respiration are higher.The total deposition fraction in oral respiration is lower than that in nasal respiration.The higher the respiratory flux is,the lower particle inhalation ratio and repeated inhalation ratio are,the higher the total particle deposition fraction is,and the lower the lower respiratory tract deposition fraction is.The smaller the particle size is,the lower the total particle deposition fraction is.As the particle size increases,the deposition location gradually moves from the lower respiratory tract to the upper respiratory tract.High-density particles are more significantly affected by gravity and inertial forces,easy to deposit in the mouth and throat area.Correspondingly,low-density particles are lighter and easier to follow the airflow into the respiratory tract’s depths.