Experts believe that the masks have another and less obvious benefit for the airlines — they provide passengers with the confidence they need to book the flights in the first place.

“I can’t speak to the science of whether masks help. But my thoughts with the mask mandate is that they help with booking leisure travel,” said Kerry Tan, professor of economics at Loyola Unversity Maryland and an expert on the economics of air travel. “I feel like it generally will give passengers peace of mind.”

Although business travel and international travel have yet to return to pre-pandemic levels, leisure travel is believed to be near 2019 levels, especially during the holiday travel season.

The number of passengers who won’t fly because they don’t like masks is likely greatly outnumbered by those who book flights because they know the people sitting around them will wear masks, Tan said. Of course he admits that is difficult to prove, since there is no hard evidence one way or another.