In silico prediction of e-cigarette aerosol particle transport and deposition within the airways

Electronic cigarettes (ECs) generate aerosols by heating up a liquid ('e-liquid') that typically consists of propylene glycol (PG), vegetable glycerol (VG), nicotine and flavouring agents. These aerosols transport through the airway tree, and lung and deposit non-uniformly in the bronchi and alveoli. Studying the transport of aerosols through lung airways is necessary because it provides information about the concentration and deposition of particles in the upper and lower airways. Here, particle transport and deposition were simulated within an anatomically-realistic airway model, which was constructed from computed tomography imaging. Particle transport was simulated using the advection-diffusion equations. Particle deposition was estimated using three different mechanisms; including sedimentation, impaction and Brownian diffusion. Results show that by increasing the particle size (PS) from 50 nm to 500 nm, the total deposition efficiency decreased from 50% to 10%, and then by increasing the PS to 3 μm, it increased to 60%. In addition, Brownian deposition was the dominant mechanism for nanoparticles (PS≪0.5μm), while the sedimentation deposition mechanism was the dominant one for microparticles (PS≫0.5μm).Clinical relevance—There is an urgent need to understand the risk that ECs pose to human health and to determine the safest methods for using these devices to support smoking cessation whilst also minimising harm. The results of this study will be used to simulate the conditions such as aerosol concentration and flow rate in airways and alveoli to use in in vitro studies.