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.
There have been troubling reports that indicate the coronavirus may be able to travel farther in the air and stay in the environment longer than is possible by respiratory droplets, which have so far been assumed to be the primary mode of transmission of the virus.
One study in Singapore found traces of the virus in air vents in patient isolation rooms. In another study, researchers at the University of Nebraska Medical Center detected extensive contamination in patient rooms as well as in air samples collected from the hallways outside rooms.
Dr. Scott Gottlieb, the former commissioner of the Food and Drug Administration, said in an interview on Sunday that the C.D.C. should put out designs for cloth masks for the public. “The value of the mask isn’t necessarily to protect you from getting sick, although it may offer some protection,” he told CBS News. “It’s to protect you from other people. So when someone who’s infected is wearing a mask, they’re much less likely to transmit infection.”
He said studies involving the flu suggested that you could reduce your ability to spread the flu by about 50 percent if you wore a mask.
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 the person who is sick is not able to wear a face mask (for example, because it causes trouble breathing), then as their caregiver, you should wear a face mask when in the same room with them. Visitors, other than caregivers, are not recommended.