Federal requirements that travelers wear masks on airplanes will be renewed if the unions have anything to say about it.

While many COVID-19 pandemic mask mandates around the country are coming down following the latest guidance issued by the Centers for Disease Control and Prevention, the federal requirement for masks on planes and other forms of public transportation have remained in effect. That could change in two weeks, when the Transportation Security Administration's mask mandate is set to expire on March 18.

But the largest flight attendants union in the U.S. opposes letting the mandate expire.

The Association of Flight Attendants-CWA, which represents more than 50,000 flight attendants at airlines including United, Alaska, Hawaiian, Spirit, and Frontier, has called for the masking requirements to be extended once again, regardless of the CDC's new recommendations.

"The conditions in aviation are the same," the union told USA Today in a statement after the CDC released its updated guidelines. "Our youngest passengers do not yet have access to the vaccine. The airplane is a unique, but controlled environment for everyone's safety. The layered approach to safety and security includes masks. Aviation is a world-wide network that harmonizes safety procedures around the world. It’s also critical that we maintain passenger confidence in the safety of air travel."

The TSA put masking requirements into place in January 2021, following an executive order from President Joe Biden. Prior to that, U.S. airlines had asked passengers to wear masks since May 2020, in accordance with recommendations from the CDC.

Nearly two years later, the state of the country is very different. COVID-19 vaccines are widely available and free for those who want protection from severe illness or death, and 75% of U.S. adults have been fully vaccinated. Cases have plummeted since the winter surge of the Omicron variant, which although highly contagious, was less severe than other strains of the virus.

Even before the CDC adjusted its masking guidance on Feb. 25 to reflect this reality, states with some of the toughest pandemic restrictions in the country began ending mask mandates. The CDC still recommends that people wear face masks indoors in parts of the country with high virus transmission, but only 37% of counties in the nation meet that measure.

However, the updated guidance on masking did not change air and rail travel requirements, including the requirements to wear a mask on public transportation, White House Coronavirus Response Coordinator Jeff Zients said Wednesday during a press briefing.

TSA officials have indicated that the masking requirements are under review, in consultation from the CDC. The decision on whether they will remain in place will come March 18, when they are set to expire.

Previously, the mask mandate has been extended three times, often at the behest of the airline industry as well as unions representing flight attendants. It remains to be seen whether the unions or science will prevail in two weeks.