One of the best things we can do to keep each other safe from COVID-19 is to cover our mouths and noses when we interact with other people. Given this fact, we can also buy face masks from any number of sources online and in person. Any consumer would want to know how well a given product works, and facial coverings for blunting a pandemic are certainly no different.
Two Indian physicists had the same thought, and set about trying to find which kinds of widely available masks did the best job of preventing the spread of the coronavirus. They've just published a paper detailing their findings, which uses the study of fluid dynamics and how air travels to come to a conclusion. The physicists were up against the human ability to cough, which can propel air and liquids from a person's respiratory tract up to three meters (nearly 10 feet) if that person leaves their mouth uncovered.
The best performance came from the highly sought N95 mask, which many medical and caring professionals are relying on in hospitals and other settings. Inside an N95, a cough is just one-tenth as powerful and travels only about four inches. Regular cloth masks also do a good job of reducing the spread of a cough, especially among regular people who are also social distancing. Don't rely on simply coughing into your elbow, though: Since there's nothing sealing your cough in, the aerosols will simply shoot out in all directions.
"Even if a mask does not filter out all the particles, if we can prevent clouds of such particles from traveling very far, it's better than not doing anything," said coauthor Padmanabha Prasanna Simha. "In situations where sophisticated masks are not available, any mask is better than no mask at all for the general public in slowing the spread of infection."