The Transportation Security Administration announced Friday that it has extended through Sept. 13 its orders requiring people to wear masks in transportation settings, including at airports, on commercial aircraft, and on buses and trains.

TSA officials said the extension of the mask requirement is consistent with updated policies from the Center

s for Disease Control and Prevention. The TSA requirement had been set to expire May 11.

“The federal mask requirement throughout the transportation system seeks to minimize the spread of COVID-19 on public transportation,” Darby LaJoye, a senior TSA official, said in a statement. “About half of all adults have at least one vaccination shot and masks remain an important tool in defeating this pandemic.”

Children under 2 and those with certain disabilities are exempt from the mask requirement, but others could face penalties if they refuse to comply. Under TSA rules, penalties for noncompliance start at $250 and increase to $1,500 for repeat offenders.

The Trump administration had rejected calls to mandate mask-wearing on planes, with the Department of Transportation in October saying it “embraces the notion that there should be no more regulations than necessary.”

But some travelers refused to follow mask rules issued by individuals airlines, sometimes responding with mockery or hostility to flight attendants who said they needed federal backup to help them with enforcement in an area that had become highly politicized.

President Biden issued a federal mask mandate for transportation on his first full day in office. The TSA action Friday extends security directives it put in place to enforce the mask mandate covering transportation, which took effect Feb. 1.

“We’ve made tremendous efforts to get the pandemic under control, but we’re not quite there yet,” said Sara Nelson, the international president of the Association of Flight Attendants-CWA. “Continuing the TSA enforcement directive for the mask mandate will keep passengers and aviation workers safe.”

According to the order, people must wear masks “while boarding, disembarking, and traveling on any conveyance into or within the United States,” as well as “at any transportation hub that provides transportation within the United States.”

The order says operators “must use best efforts” to ensure masks are worn, including “at the earliest opportunity, disembarking any person who refuses to comply.” It says enforcement will be handled by the TSA and “by other federal authorities and may be enforced by cooperating state and local authorities.”

The CDC updated its mask guidance this week to say fully vaccinated people do not need to wear masks outdoors unless they are in crowded settings. The TSA’s requirement released Friday applies to passengers and transportation employees alike, “including those already vaccinated.”

“We will continue to work closely with the Centers for Disease Control and Prevention to evaluate the need for these directives,” LaJoye said.

A CDC mask mandate for transportation, which originally set out the requirement, does not include an end date, and the TSA can further extend transportation enforcement directives. The mandate “will remain in effect unless modified or rescinded based on specific public health or other considerations,” or when the secretary of health and human services finds there is no longer a public health emergency, according to the CDC order.

Detailed rules and practices have emerged in the three months that the federal mask mandate has been in place.

The Department of Transportation has cited CDC guidance in answering questions from workers and others who are most affected by the mandate. Among the questions officials have addressed: “What should transit agencies do when drivers with glasses report difficulty wearing masks because their glasses fog up?”

The department noted that the CDC recommends using a mask “that fits closely over their nose or has a nose wire to help reduce fogging,” or trying anti-fogging spray on their glasses. And it said transit agencies should “work with drivers on mask fit” to cut down on fogging.

“In certain circumstances, where this issue cannot be resolved, the CDC Order provides for exemptions to ensure workplace safety and safe operation of the transit vehicle,” the department said.