Does prolonged wearing of a facemask cause harm?

Question I have heard about concerns that wearing a mask for a prolonged period of time can cause you to retain or breathe in more carbon dioxide (CO2) or get less oxygen and this can make you sick.  I even heard about people who had car accidents they felt were due to this issue.  Does mask wearing for a prolonged time cause this?

Answer:  Prolonged use of any face mask, including the N95 respirator, has not been shown to cause carbon dioxide toxicity or lack of adequate oxygen in healthy people. For some persons with severe chronic lung disease, wearing a mask may make breathing more difficult, but not because of CO2 retention.

Recall, there are health care workers who routinely wear masks for prolonged periods as part of usual care (such as when performing surgery) and adverse effects from this practice have not been reported.

Cloth masks reduce the number of microorganisms that someone releases into the air. So, the more people wear masks in an area, the fewer potential viral droplets go into the space, and the less risk that someone will be exposed to the virus.