Effects of nasal cavity and exhalation dynamics on aerosol spread in simulated respiratory events

Coughing and sneezing are critical mechanisms for the transmission of airborne respiratory diseases, dispersing pathogen-laden aerosols into the environment. Previous human volunteer studies provided valuable insight into aerosol dynamics but lacked reproducibility due to individual variations. This paper presents a novel, replicable experimental setup using three dimensional models of the upper respiratory tract and nasal cavity to simulate isothermal human-like coughs and sneezes. Results indicate that nasal cavity involvement decreases horizontal aerosol cloud spread while enhancing vertical dispersion. Incorporating this experimental data with theoretical models improves predictive accuracy of aerosol cloud evolution, particularly for indoor environments. Finally, a single novel analytical expression for the evolution of the particle cloud tip is derived that accurately predicts the cases studied.