evidence: Scientific evidence shows wearing a face mask reduces the spread of COVID-19. Wearing a face mask also doesn’t significantly impede the exchange of oxygen and carbon dioxide, as gas molecules are many times smaller than the pores of even an N95 mask. COVID-19 is mainly transmitted through infectious liquid particles spread from infected to uninfected individuals. Masks act as simple physical barriers that reduce the dissemination of these liquid particles, which are generated by people when they cough, sneeze, or speak.