The requirements will go beyond airplanes. According to the Biden fact sheet, the administration will require “mask-wearing in airports, on certain modes of public transportation, including many trains, airplanes, maritime vessels, and intercity buses.”

While evidence on the risks of flying during the pandemic varies, there is broad consensus that wearing a tight face covering can significantly reduce the risks of transmitting the Covid-19 virus.

One of the actions with the highest potential impact is a requirement that people arriving in the U.S. from other nations adhere to what have previously been unenforced quarantine guidelines from the CDC.

The CDC suggests international travelers get a second test for the virus within three to five days after arrival and that they stay at home or in isolation for seven days — even if the test is negative. People who don’t get tested should isolate for 10 days, the CDC says.

Similar restrictions in the U.K. have reduced travel and have been opposed by airlines and others in the travel industry, who have said aggressive testing should be enough to slow spread of the disease.

The U.S. Travel Association, which represents more than 1,000 tourist-related businesses, supports the mask and testing requirements, but is opposed to mandatory quarantines, said Tori Barnes, executive vice president for public affairs and policy at the group.

“We think there is a challenge when it comes to quarantines,” Barnes said.

She cited survey data from the International Air Transport Association that found 83% of people wouldn’t travel if forced to isolate at their destination.

Airlines for America, a trade group for large U.S. carriers, has said it would prefer testing of international passengers instead of quarantines. The group hasn’t commented on the Biden plan.

While the impact of a quarantine on the dramatically reduced number of passengers from European nations would be minimal, travel to places such as Mexico has remained relatively strong during the pandemic and could be depressed under such an order.

The executive order also calls for unspecified “consideration of additional public health measures in domestic travel,” according to the Biden fact sheet.