Fig. 2From: The effects of facemasks on airway inflammation and endothelial dysfunction in healthy young adults: a double-blind, randomized, controlled crossover studyExperimental setup for measuring filter efficiencies of N95 facemasks with the headform based on particle number in ambient air. Key facial parameters of a medium-size headform in China include face length (122Â mm), face width (145Â mm), and interpupillary distance (62.5Â mm) [24]Back to article page