The virus particle is several dozen nanometers in size and passes through the medical mask without delay. However, directly at the exit of the patient, viruses do not fly out in free form, but in the form of drops of saliva, sputum, nasal secretion, containing the virus, which are already easily delayed by the mask. In the air, these drops quickly dry out and break down, and the virus becomes free and unmatched. Therefore (and for a number of other reasons, including the fact that the mask generally works poorly as an anti-dust respirator), the mask should be worn by the patient.