For example, some medical organizations claim that wearing a mask only protects others from you if you are carrying the virus, but urge you to wear one if you are in close contact with a COVID-19 patient — which infers that a mask could protect you from an infected person.

The advice raises several questions. First, many people can be carrying the virus and not know it because they are asymptomatic and have not been tested. How would these people know to wear a mask? Secondly, if a mask is indicated if you are in close contact with a COVID-19 patient, then that would indicate that a mask does protect you from others and not just others from you. So, which is the truth?

There is another element to the conflicting advice. Some medical experts claim that wearing a face mask is harmful to the wearer. Not only does it not protect you, they say, but it can limit your oxygen and even redirect harmful pathogens that you may be carrying back into your airway. As COVID-19 lockdowns end and people are getting out in the public again, what does the evidence say about wearing masks?