TABLE I.

Summary of different masks, types of materials used, number of layers or threads/inch present, and average distance traveled by the tracer particles beyond which their presence is unnoticeable.

Type of mask	Material	Number of layers or threads/in.	Average distance traveled by sneeze
Without mask	…	…	∼25 ft
Two-layered mask	Cotton	50 threads/in.	∼1.5 ft
Three-layered mask	Cotton	65 threads/in.	∼1.5 ft
Face shield	Polycarbonate	…	∼1 ft
Two-layered mask with a face shield	…	50 threads/in.	∼0.5 ft
Surgical mask	Polypropylene	Three layered	∼2.5 ft
Surgical mask with a face shield	…	…	∼0.4 ft
N-95	Synthetic polymer fibers	Five layered	0 ft in the forward direction
			∼2 ft in the backward direction