Beyond England, Northern Ireland, Norway and Barbados, destinations that do not currently have mask requirements in the air include Mexico, St. Lucia, the Bahamas and Jamaica. The United States, Scotland, Italy and China are among the many countries that continue to require masks on planes.

Airport rules may be stricter than plane rules on a given route, meaning a traveler might have to put on a mask upon arrival. Airports in Norway, Denmark and England have been outliers in lifting mask requirements, according to the Airports Council International, a trade organization representing nearly 2,000 airports.

When can I stop flying with a mask in the United States?

Maybe on April 19, if — and that’s a big if — the White House does not extend the federal mask mandate further. Even flight attendants are divided on whether the mandate should be extended again, with some saying that the mask rule is not worth it, given the problems enforcing it, while others argue that the rule is critical to keeping medically vulnerable travelers safe.

Should Covid case counts affect mask mandates?

It depends on whom you ask.

Across the world, case count numbers vary. In recent weeks, case numbers have dipped to their lowest level since June in the United States. Canada is also down to its lowest number of cases since December. But in many other places, cases are rising. As England moved away from airport and airline mask mandates on March 16, case counts hit their highest point in nearly a month. Meanwhile, a highly transmissible subvariant known as BA.2 is pummeling some parts of Asia and Europe. And on Sunday, Dr. Anthony S. Fauci, the Biden Administration’s top adviser on the pandemic, predicted that the United States would eventually see a similar “uptick” of BA.2 cases.

“Covid is not over,” said Leonard Marcus, the director of Harvard’s Aviation Public Health Initiative, which produced a report that some airline executives have used to rationalize ending mask requirements. Dr. Marcus said that it’s too soon for him to have an opinion on whether BA.2 merits an extension of the federal mask mandate. But once lifted, he said, a mask mandate will be difficult to reinstate.

Some proponents of ending mask mandates argue that so long as vaccines are preventing serious disease, case counts are irrelevant, because most international travelers are vaccinated.

In a statement announcing the end of its mask requirement last week, Heathrow Airport embodied this line of thinking, mentioning “the strong protection provided by vaccination programs around the world” and an embrace of a “move towards learning to live with Covid longer term.”