From: Rebecca Watson:
Here’s the thing, obviously most people know this isn’t true. I’d guess that even a lot of the people who are saying it know it’s not true. We know it’s not true for several reasons, without even thinking about it very hard. For a start, we know that medical professionals wear masks all day long in strenuous environments and have been doing so since the mid 19th century. If wearing masks caused physical problems, we would know it by now because there would be millions of doctors and nurses dying of oxygen deprivation after a 12-hour shift.