The U.S. Department of Homeland Security (DHS) today authorized Transportation Security Administration (TSA) workers to enforce President Joe Biden's mask mandate "at TSA screening checkpoints, and throughout the commercial and public transportation system," according to CNN ,

Acting Secretary David Pekoske today signed a Determination of National Emergency , which empowers the TSA to "take actions consistent with the authorities" of its federal jurisdiction to enforce the Centers for Disease Control and Prevention’s (CDC) mask mandate. The CDC’s order , issued last week and taking effect on February 1, makes the refusal to wear face masks on planes and other public forms of transportation (buses, trains, ferries, subways, taxis, ride-share vehicles, etc.) a violation of federal law.

"This includes supporting the CDC in the enforcement of any orders or other requirements necessary to protect the transportation system, including passengers and employees, from Covid-19 and to mitigate the spread of Covid-19 through the transportation system, to the extent appropriate and consistent with applicable law," Pekoske wrote.

The CDC’s mandate builds upon an executive order that Biden signed on Inauguration Day, and requires that people wear masks that cover both the nose and mouth while using public means of transportation and while waiting in airports, terminals, stations, etc. The CDC dictates that masks must include two or more layers of breathable fabric, and be secured around a person’s head using ties, ear loops or elastic bands.

People must also wear their masks properly in order for them to be effective, so the CDC requires that masks fit snugly around the face, and they must be free from punctures or exhalation valves. Gaiters are also permissible, but they must consist of at least two layers of fabric or be folded over to supply two layers. Scarves and bandanas don’t fulfill the requirements.

The CDC’s order specifies that face shields and goggles can be used in addition to, but not in place of, wearing a mask. It also provides exemptions for children under the age of two and people with disabilities that would preclude their wearing a mask.