In Phase II, the respiratory effects of wearing N95 masks were examined. Each subject underwent two 15-minute exercise cycles on a treadmill. Each subject wore a Hans Rudolph mask, similar to that in Phase I, attached to a laboratory-based metabolic cart (Cortex Metalyser 3BR2, Leipzig, Germany) in order to obtain real time respiratory parameters during exercise. In the first (control) cycle, subjects wore the Hans Rudolph mask with the outlet opened to ambient air. In the second (N95) cycle, outlets of the Hans Rudolph masks were covered by materials obtained from representative supplies of N95 masks (3M, St. Paul, MN, USA). N95-mask materials were trimmed to form an airtight seal over the Hans Rudolph mask outlet so that the air flow resistance on inspiration and expiration would come from the mask material, simulating the actual wearing of an N95 respirator (Fig. 2) This experimental design allowed each subject to act as her own control. Tight fitting Hans Rudolph respirator masks used in Phase II. (a) Control cycles with outlet open to air, and (b) N95 cycles with outlet covered by N95 mask materials
TBH this is basically the whole thing. I could probably have just posted this one image and everyone who's paying attention would understand.
Pregnant nurses were tested while wearing a spirometry mask, with or without a small piece of N95 material taped over the hole.
The...tiny...little...hole.
