Unfortunately the fit hypothesis was not tested in the study, so it doesn't answer any of those questions. The real issue addressed here is with the valves, no

Unfortunately the fit hypothesis was not tested in the study, so it doesn't answer any of those questions. The real issue addressed here is with the valves, not the mask type or fit - outflow is not filtered through the valve, only inflow. The difference is stark: https://aip.scitation.org/doi/pdf/10.1063/5.0031996 https://aip.scitation.org/doi/pdf/10.1063/5.0031996