Joe Biden’s Transportation Security Administration (TSA) is mandating passengers wear masks on trains, buses, airplanes and airports through January 18, the agency announced earlier this week.

The current mask mandate was set to expire on September 13.

The San Francisco Chronicle reported on the announcement, which the TSA claims in necessary because of the Delta variant of the coronavirus:

In a statement to The Chronicle, a TSA spokesperson said “the purpose of TSA’s mask directive is to minimize the spread of COVID-19 on public transportation.”

California briefly relaxed indoor mask requirements June 15 when it reopened, though many cities and counties, including San Francisco, have reinstated mask requirements as the state experienced a fourth surge in cases this summer due to the delta variant.

The Chronicle reported employees at the San Francisco Municipal Transportation Agency have to get vaccinated or risk losing their jobs “once a vaccine gains full approval under a city order for public workers.”

The Chronicle report continues:

Leaders at other transit agencies, such as BART, are debating whether to implement a vaccine mandate among their workers but have stopped short of making vaccines a requirement. BART, which had its return-to-office plans disrupted by the delta variant’s spread, is offering its employees two floating paid holidays if they get vaccinated and submit proof by Sept. 15 as part of an incentive plan.

The federal Centers for Disease Control and Prevention (CDC), however, says masks are unnecessary if fully vaccinated or for people who are outdoors

“If you are not fully vaccinated and aged 2 or older, you should wear a mask in indoor public places,” the CDC website states. “In general, you do not need to wear a mask in outdoor settings.”

Follow Penny Starr on Twitter or send news tips to pstarr@breitbart.com