Procedure for measuring air leakage rate; A shows the setup for measuring air leakage rate from a mask during simulated exhalation using a facial model in a laboratory setting. The mask-fitting tester MT-05U was used for the measurements. A particle generator maintained a constant particle concentration in the room, and exhaled air was simulated using a nebulizer. B is a photograph illustrating the exhalation process, in which simulated exhaled air is released through tubes positioned within the nasal and oral cavities of the facial model.