The CDC continues to recommend that people wear masks on public transit, a Biden administration official said.U.S.

District Judge Kathryn Kimball Mizelle in Tampa said the CDC had failed to adequately explain its reasons for the mandate, and did not allow public comment in violation of federal procedures for issuing new rules. Mizelle was appointed by former President Donald Trump in 2020.

White House press secretary Jen Psaki, at a news conference Monday, said the administration is reviewing the court's ruling and the Justice Department will determine whether it will appeal. The Justice Department declined to comment when asked by CNBC.

The Association of Flight Attendants, the nation's largest union of cabin crews, has recently taken a neutral position on the mask rule because its members are divided about the issue. On Monday, the union's president appealed for calm on planes and in airports.

"The last thing we need for workers on the frontlines or passengers traveling today is confusion and chaos," union leader Sara Nelson said.