C.D.C. Weighs Advising Everyone to Wear a Mask Masks work by stopping infected droplets spewing from the wearer’s nose or mouth, rather than stopping the acquisition of the virus from others. Both medical grade N95 masks and flat face masks are made of a special melt-blown fabric, which is able to stop infectious particles even finer than a micron in diameter. But in many Asian countries, where everyone is encouraged to wear masks, the approach is about crowd psychology and protection. If everyone wears a mask, individuals protect one another, reducing overall community transmission. And places like Hong Kong and Taiwan that jumped to action early with social distancing and universal mask wearing have gotten their cases under much greater control. This is what the C.D.C.’s guidelines currently say: “If you are sick: You should wear a face mask, if available, when you are around other people (including before you enter a health care provider’s office). If you are caring for others: If t