People can get a false sense of security from flimsy gauze, and linger too long outdoors in toxic air, argue Wei Huang and Lidia Morawska.
Across Asia, and increasingly elsewhere, people are wearing medical masks in the street. Young and old, people are tying gauze squares over their noses and mouths when they step outside.
In China, the habit began in 2003, when health authorities recommended wearing medical masks to slow the spread of severe acute respiratory syndrome (SARS). Today, many Chinese citizens wear masks regularly, in a range of fabrics and styles, to lower the risk of catching or transmitting colds or influenza — we, too, wear them for this purpose.