Biden just signed an executive order that mandates mask-wearing while flying and utilizing most forms of mass transit

• President Joe Biden signed an executive order on Thursday requiring air passengers wear masks.
• Airports and commercial aircraft are included, as well as other modes of transport including trains.
• New testing requirements to enter the US from abroad are also being reviewed.

President Joe Biden on Thursday signed an executive order mandating mask-wearing on most forms of domestic travel in the first act of federal intervention on social distancing in the skies during the pandemic.

The "executive order on promoting COVID-19 safety in domestic and international travel" requires masks to be worn by the public while in airports or on commercial aircraft, trains, public maritime vessels including ferries, intercity bus services, and all forms of public transportation.

All 11 major US airlines and Amtrak currently require masks, but the order gives federal backing to enforce the rule.

"Accordingly, to save lives and allow all Americans, including the millions of people employed in the transportation industry, to travel and work safely, it is the policy of my Administration to implement these public health measures consistent with CDC guidelines on public modes of transportation and at ports of entry to the United States," Biden's executive order reads.

Biden also signed an executive order on Wednesday mandating Centers for Disease Control and Prevention guidelines be followed for mask-wearing while in federal buildings or on federal lands.

"CDC recommends that people wear masks in public settings, like on public and mass transportation, at events and gatherings, and anywhere they will be around other people," the public health agency's website says.

The move comes as individual airlines have already banned over 2,500 passengers for mask non-compliance since the spring. Delta Air Lines and United Airlines have banned nearly 1,500 passengers combined as of mid-January for refusing to mask up while flying, with more being added each day as some flyers attempt to flout the rule.

For airlines, a key factor for enforcing the policy is maintaining an already fragile recovery that's still seeing less than one million daily passengers on most days, according to Transportation Security Administration data. An in-flight outbreak could worsen fears of proximity spread onboard airliners and destroy the gradual gains made since March.

The effectiveness of mask-wearing policies has also encouraged airlines to ditch seat-blocking policies, confident in onboard high-efficiency particulate air systems. Delta is currently the only airline still blocking middle seats in economy while the rest have resorted to filling planes.

The days following the US Capitol riots saw an increase in unmasked flyers, with United banning around 60 passengers the week of January 4 alone, a spokesperson told Insider. Passengers with a medical condition can request an exemption to the rule and masks can be taken off when actively eating or drinking.

The order also solidifies a new CDC policy that requires international arrivals in the US to present a negative COVID-19 test to be granted entry. Starting January 26, the State Department says that flyers must have a negative COVID-19 test taken within three calendar days prior to their departure, or proof of recovery within the past 90 days, to be verified by airlines before boarding.

Biden called upon the Secretaries of Health and Human Services, Transportation, and Homeland Security to review the policy within 14 days and determine the next step moving forward. The agencies will judge which types of COVID-19 tests qualify, the timing of the tests, how travelers can present proof of the test, and testing alternatives including mandatory self-quarantine.

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Also being called into consideration is testing immediately before departure, a policy that was recently enacted in the Netherlands, where inbound travelers must present a negative rapid test taken within four hours of departure effective January 23. The Dutch policy is intended to restrict international travel, so much so that KLM Royal Dutch Airlines canceled all of its long-haul international flights in response.

This mandate might not be the last federally backed social-distancing effort for travel, as the order also advises the Secretary of Transportation and Secretary of Homeland Security to make recommendations on "how their respective agencies may impose additional public health measures for domestic travel."