Wearing a used mask could be worse than no mask amid COVID-19: study

Wearing a used mask could be more dangerous than not wearing one at all when it comes to warding off COVID-19, a new study has found. A new three-layer surgical mask is 65 percent efficient in filtering particles in the air — but when used, that number drops to 25 percent, according to the study published Tuesday in the Physics of Fluids.-- More...