Table E1.

Particle concentrations from the protection phase of the study.^⁎

Mask	Median	Range	Interquartile Range
N95 mask	0.07	0–0.67	0–0.15
N95 O2 mask, 2 L/min	0.13	0–4.58	0–0.36
N95 O2 mask, 10 L/min	0.06	0–2.19	0–0.33
NRM mask, 2 L/min	52.93	3.10–141.88	43.12–75.31
NRM mask, 10 L/min	15.26	0.27–98.60	6.90–29.90

NRM, Nonrebreathing mask.

^⁎The protection function of each mask was quantified by measuring the concentrations of particles inside the mask and expressing each discrete measurement as a percentage of average external concentrations.