In laboratory simulations, face shields blocked only 2% of exhaled cough aerosols, whereas N95 respirators blocked 99% and medical masks blocked 59%. Comparison: Face Shields vs. Masks
Simulations show that high-velocity vortex rings produced by a sneeze can reach the top and bottom edges of a shield in just one second. If a wearer inhales as these particles arrive, they can draw infectious air directly behind the shield. Study: Face Shields Not a Good Mask Substitute
Studies published in journals like Physics of Fluids highlight several critical reasons why face shields fail as standalone protection: In laboratory simulations, face shields blocked only 2%
While shields block the initial forward "jet" of a cough or sneeze, smaller aerosolized droplets can easily flow around the sides and bottom of the visor. In laboratory simulations