Adding a layer of nylon stocking could make DIY coronavirus masks more protective

The homemade masks that millions are wearing in the US and elsewhere have always been a better-than-nothing solution for preventing the spread of the virus that causes Covid-19. Only N95 respirators can effectively block contaminated droplets and aerosols expelled from someone who is infected. For the rest of us, cloth masks made from t-shirts, bandanas, bras, or jeans are sufficient, and mandatory in some states, not for the sake of the people wearing them, but everyone else.