President Joe Biden’s administration will extend a requirement for U.S. airline travelers to wear masks for another month, while working on a policy about how and when to roll back the rule, according to officials familiar with the matter. 

The federal mask mandate for domestic travel on planes, trains and other transit is set to expire on March 18 and will be extended to April 18, the officials said, speaking on condition of anonymity ahead of an announcement. 

During the weeks ahead, the Centers for Disease Control and Prevention will work on a revised policy for when, and how, mask rules should be eased on public transportation corridors, one of the officials said.

The requirement was imposed in the earliest days of Biden’s administration and has been regularly extended since. 

The mask rule has been a double-edged sword, particularly in the airline industry.

Requiring face coverings has eased fears of infection and helped fuel an airline-travel comeback since carriers lost more than 95% of passengers in early 2020. At the same time, the requirement was a catalyst for an unprecedented rise in violence on flights. Almost three-quarters of the 5,981 unruly passenger reports last year were related to objections to masks, according to Federal Aviation Administration data.

CDC Director Rochelle Walensky said earlier this month she’d weigh the latest science on masks and transmission, as well as “the frequency that we may encounter a variant of concern or a variant of interest in our travel corridors,” before making a decision.

“People rely on those corridors for getting to work and for, you know, other reasons. So, that’s among the reasons that we want to revisit this in a separate way,” she said on March 2.