People are scared right now. The Coronavirus could definite become a huge threat and thus people are seeking ways to protect themselves. One of the most obvious ways would be to always wear a face mask when going somewhere outdoors. This has in turn caused a massive surge in the value of face masks (and gas masks).
If this hasn't happened in your area yet, it might be wise to stock up on a few. Better safe than sorry. Otherwise a face mask can always be useful when cleaning with chemicals.