Airlines are generally requiring passengers to wear face masks on board. They aren't necessarily enforcing the requirement, though. Many people do get health related exceptions, including young children, and putting flight attendants in a position of adjudicating whose claims are legitimate during the flight is awkward.

Besides, while cloth masks provide some protection from spread they're not as effective as hospital masks, and nowhere near as effective as respirator masks. But they do provide some level of comfort to other passengers.

And though the requirement says face masks there's not much definition of what constitutes an acceptable mask. Someone might want to tell Alyssa Milano, by the way, that crocheted masks with holes in them aren't helpful.

Guys, who wants to tell her? https://t.co/0q3tX0z97e

- Billy Hallowell (@BillyHallowell) May 23, 2020

With personal protective equipment in short supply, people have made due with what they have. Airline amenity kit eye masks work. One passenger decided to test the limits of what would be acceptable.

What about a man on a flight out of LaTrobe, Pennsylvania who put womens underwear on his face and called it a mask? This happened on Spirit Airlines, natch. The carrer says this was not an 'appropriate' mask.

Spirit Airlines investigating after man seen on plane in Latrobe using women's underwear as 'mask' https://t.co/1RnxRu0SdF pic.twitter.com/dspKcRwwjw

- WPXI (@WPXI) May 22, 2020

By the way this does not even appear to be an isolated incident on public transportation.

tag