I have been following this for a long time, and experts disagree, but the FDA says you should only wear the ones that follow their guidelines. The problem is the weave of the masks and how small the virus is.
The worldwide infection reports show that countries that do not have much HVAC ventilated facilities have less than 5 % of the infection rates of developed countries where HVAC is dominant. The major cause of coronavirus spread seems to be airborne in closed facilities with HVAC. In Vietnam, they are particularly careful about this and even hospitals employ open window ventilation. They have no coronavirus deaths and the infection rate is about 0.05% of the US. I think the USA has bungled this big time.
There have been extensive randomized controlled trial (RCT) studies, and meta-analysis reviews of RCT studies, which all show that masks and respirators do not work to prevent respiratory influenza-like illnesses, or respiratory illnesses believed to be transmitted by droplets and aerosol...
Regardless of any studies, masks should not work according to my logic. If a person is infected, he will be breathing the stuff trapped in the mask and his infection may become more severe, even fatal. He needs plenty of fresh air. He should not be out with others.
If he is not infected, he is not protected because the eyes are exposed unless he wears helmet type covering with air supply.