It is essential to study the viral droplet’s uptake in the human respiratory system to better control, prevent, and treat diseases. Micro-droplets can easily pass through ordinary respiratory masks. Therefore, the SARS-COV-2 transmit easily in conversation with a regular mask with 'silent spreaders' in the most physiological way of breathing through the nose, indoor and at rest condition. The results showed that the amount of deposited micro-droplets in the olfactory epithelium area is low. Also, due to receptors and long droplet residence time in this region, the possibility of absorption increases in the cribriform plate. This phenomenon eventually could lead to brain lesion damage and, in some cases, leads to stroke. In all inlet flow rates lower than 30 L/min inlet boundary conditions, the average percentage of viral contamination for upper respiratory tract is always less than 50% and more than 50% for the lungs. At 6L/min and 15L/min flow rates, the average percentage of lung contamination increases to more than 87%, which due to the presence of the Coronavirus receptor in the lungs, the involvement of the lungs increases significantly. This study's other achievements include the inverse relationship between droplets deposition efficiency in some parts of the upper airway, which have the most deformation in the tract. Also, the increased deformities per minute applied to the trachea and nasal cavity, which is 1.5 times more than usual, could lead to chest and head bothers.

Background: The lung Extracellular Matrix (ECM) contains a considerable part of the parenchymal cells. It contains three essential components: elastin and collagen within a proteoglycan (PG) viscoelastic network. Elastin provides the lung’s elasticity property, a necessity for normal breathing, while collagen prepares structural support and strength, and PGs give stability and cushioning within tissue loading. Bacterial and viral respiratory diseases are dependent on changes in the ECM ingredients, which result in an alteration of the lung tissue strength. Purpose: In the present study, this variation was investigated by changing the volume ratio of the ECM ingredients in the viscoelastic model. Results: As a result, the relaxation curves continuously declined by reducing the volume ratios of elastin, collagen, and PGs; subsequently, the lung stiffness decreased. Also, the Standard Linear Solid (SLS) model-based results demonstrated excellent accordance with empirical data with only minor deviations. The resting relaxation modulus and the creep modulus for the ECM tissue were 51 kPa and approximately 0.02 kPa, respectively, and the maximum total modulus of elasticity reached 121 kPa. Conclusions: Moreover, this model demonstrates individual alveolar mechanical behaviours and adds another pathway to the generalized Kelvin-Voigt and Maxwell models in predicting the progress of lung diseases.