Effectiveness of face shields in preventing the spread of airborne diseases through coughing: a CFD simulation study

This study evaluates the protective efficacy of face shields as Personal Protective Equipment in limiting the spread of airborne diseases, such as COVID-19. Computational fluid dynamics simulations using a simplified two-dimensional model were conducted to systematically evaluate the influence of shield coverage angles, wearer orientation angles, and droplet sizes on droplet infiltration into the risk zone-the area between the shield and the face. The simulations tracked the movement of approximately 36,900 particles, representing a cough event, under various configurations of shield geometry and head alignment. Results show that face shields have the potential to reduce droplet exposure compared to no protection, with larger coverage angles providing high protection in forward-facing scenarios. However, particles infiltrated the risk zone in oblique orientations and with smaller coverage angles, highlighting vulnerabilities under certain conditions. Furthermore, the vulnerability is increased when the inhalation is considered. Overall, the study offers insights into the limitations and benefits of face shields, providing evidence-based guidelines for their more effective use in both healthcare and public settings.