But even then, mask manufacturers are not healthcare professionals or experts in pathogen transmission.
A friend told me in June of 2020 that, it is common sense , that, a person is going to get less oxygen into their bodies, when wearing a mask.
I looked on line, and found, that, masks do not reduce the amount of oxygen people get into their bodies ---or not significantly--- unless, they had pulmonary issues ex. asthma or emphyszema etc. Why? Because we breath harder to get the oxygen we need.
So it is little like when we see and automobiles wheels rolling along and when some speed is reached, it appears to us visually, that, the wheels are rolling in reverse. This defies our common sense, however, it does not defy rationality and logic, once we understand the cosmic principles behind the visuals.
The moral of the story is, that, we need a balance of triangulate, to approach truth;
1} rational thought, --knowing we have not gone insane--
2} logical thought, -- knowing the cosmic principles associated with the visual---,
3} common sense ---that is lacking, until we consider the two above---.