(CNN) — The Transportation Security Administration is set to extend the federal public transportation mask mandate for another 30 days, an administration official told CNN, pointing to guidance from the US Centers for Disease Control and Prevention.

The mandate is one of the last remaining broad requirements that Americans wear masks in public places. It applies to mass transportation including planes, trains, buses and hubs like airports.

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The official’s comments came after CNN reported that federal officials began notifying stakeholders in the airline industry of the upcoming announcement. Three sources, including two industry officials and a government official, described the conversations to CNN on the condition of anonymity.

The requirement, which now extends to April 18, was previously set to expire a week from Friday, and the policy will be reviewed over the next month, the official said.

“During that time, CDC will work with government agencies to help inform a revised policy framework for when, and under what circumstances, masks should be required in the public transportation corridor,” the official said. “This revised framework will be based on the Covid-19 community levels, risk of new variants, national data, and the latest science. We will communicate any updates publicly if and/or when they change.”

One source told CNN that means the CDC may ultimately allow the mandate to lift before the 30-day period is up if transmission rates of the virus nationwide drop to low enough levels.

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The federal announcement comes as many state and local mask mandates have been dropped or are set to be rescinded.

In the skies, requiring masks has proven to be a divisive issue. Flight crew unions applauded the measure for protecting flight attendants who can not avoid close contact with scores of passengers.

But some passengers refused, leading to more than 4,800 reports to the Federal Aviation Administration of passengers who turned disruptive or violent while flouting the mask rule. The agency adopted a zero-tolerance approach to in-flight outbursts, which surged during the pandemic.

Some in the airline industry have described a concern about lifting the mandate too soon, ahead of another wave of the coronavirus.

“What we really don’t want is to lift the mandate and have to reimpose it,” one of the sources told CNN.

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