The retired inventor of N95 masks is back at work, mostly for free, to fight COVID-19

He retired right before the coronavirus hit; his devotion to duty forced him to come back. The N95 respiratory mask that has become a critical commodity in the wake of the coronavirus pandemic was invented by Peter Tsai. Sydney Page of The Washington Post tells us how Tsai, who had retired shortly before the virus hit, came out of retirement and has been back at work, mostly for free, to help with the efforts to fight COVID-19.