FILE PHOTO: Dr. Nicole McCullough, a global health and safety expert at 3M, reveals the various layers of a N95 respirator mask, which includes the proprietary filter media, the middle layer, during a media demonstration at a laboratory of 3M . The company has been contracted by the U.S. government to produce extra marks in response to the country’s novel coronavirus outbreak, in Maplewood, Minnesota, U.S. March 4, 2020. REUTERS/Nicholas Pfosi
