Ever since Covid-19 began spreading in the U.S., state governments have been scrambling to find and secure N95 respirator masks, the kind that seal against the face and filter out infectious particles, protecting frontline workers from inhaling the coronavirus. A national shortage has led states to buy these masks from uncertified foreign producers or from producers that sell foreign-certified products. “Every state has had to go and buy whatever they can find,” says William Herzog, an assistant leader of the Advanced Materials and Microsystems Group at MIT Lincoln Laboratory. “There’s…
